Nuclear Power

[garytse86]

What do you think about nuclear power?

How dangerous is nuclear power plants?
and from a physics point of view, how efficient is nuclear power c.f. coal-powered plants etc.?

and what about the advantages? There are no greenhouse gases released but what about nuclear waste?

[russ_watters]

There are quite a number of threads here on the subject, but briefly.What do you think about nuclear power? It is the only large scale, currently viable future source of power in use. In other words, with any luck, in 50 years, we won't be using coal, oil, gas, windmills, solar cells, etc. With any luck, we'll have fusion by then, but even if we don't, nuclear fission can handle our needs. How dangerous is nuclear power plants? So safe that statistics are meaningless when discussing nuclear safety. If you ever hear someone say "if this nuclear plant has a meltdown...", ask "how likely is that?" The answer is: so unlikely that the chance can't even be measured. ...and from a physics point of view, how efficient is nuclear power c.f. coal-powered plants etc.? Slightly less efficient than other types of power plants. This question has little meaning though: consider that gas heat for your house is 80% efficient, heat pumps are about 30% efficient, and electric is 100% efficient. Which should you use? (answer: usually gas, sometimes heat pump). and what about the advantages? There are no greenhouse gases released but what about nuclear waste? Nuclear power produces small quantities of waste (orders of magnitude less than coal or oil) and is not released into the environement, ie. it produces no pollution.

[theCandyman]

I think nuclear power is a great step foward in both protecting our enviroment and producing energy. As for its dangers, it is just like fire, the more carelessly it is used, the more likely it will be dangerous. I'm no physict so I can't comment much on efficency of plants. The waste? That is the only problem I see in using it, but it is the lesser of two evils considering other energy sources.

[Astronuc]

Nuclear power is as safe as the designers, manufacturers and operators make it. There were safety margins built in the original designs, and with a gain of experience, some of the margins have been used to improve performance. However, if operators get sloppy, then nuclear power can become unsafe. (This is an overly simplist answer - but it is essentially accurate).

Nuclear plants are comprised of reinforced concrete structures (e.g. containment building), which contain the reactor system. These structures are more robust than the structures housing fossil plants of similar capacity.

Commercial nuclear power plants use fission (nuclear process) to generate thermal energy, which in turn is converted either through gas or steam turbines to produce mechanical energy, which in turn drives an electrical generator which produces electrical energy.

Most commercial reactors are light water reactors LWRs (PWRs and BWRs) which use the Rankine cycle to convert thermal to mechanical energy in steam turbines. CANDUs (heavy water reactor) also use the Rankine cycle, and so do the Gas Cooled Reactors in UK.

The efficiency of the Rankine cycle is temperature limited in order to limit coolant pressure or prevent corrosion (prolong life of components in radiological areas). For most nuclear plants using the Rankine cycle this means efficiencies of 32-34%. Coal plants can use superheated steam which can provide efficiencies in the high 37-38%, and modern supercritical coal plants may have efficiencies of up to 45% gross. High temperature gas-cooled reactors have been designed with theoretical effiencies of about 42%.

Gas-fired plants based on aircraft (jet) turbines (so-called aeroderivative turbines) can achieve thermal efficiencies of 42-45%, and if they feed a steam cycle (as in a combined-cycle plant), then the plant can achieve up to 60% thermal-to-mechanical conversion efficiency.
====================================

As for the waste (backend) - the long term storage solution in the US depends on the resolution of Yucca mountain as the final repository of the spent fuel from the US.

In the case of fossil plants, many (particularly coal) plants have filter systems to filter ash, otherwise the waste is discharged to the atmosphere (green house gases, and traces of Hg, U and whatever ash is not collected). Some old plants may have less efficient filtering systems - but that is a political-economic issue (i.e. we have the technology, but if it costs too much, we may not use it).

As for the front end - both uranium and coal come from the ground and mining it means lots of waste. That's another political-economic issue.

[Morbius]

What do you think about nuclear power?

How dangerous is nuclear power plants?
and from a physics point of view, how efficient is nuclear power c.f. coal-powered plants etc.?

and what about the advantages? There are no greenhouse gases released but what about nuclear waste?

Gary,

Nuclear power plants are VERY SAFE!!

Compare the US experience of nuclear power with other activities.

Do you think airliners are safe? Every few years an airliner crashes and
kills a couple hundred people. Is anyone calling for the shutdown of the
air travel industry?

How about cars? Each year automobile accidents kill on the order of
50,000 people. Are cars safe? Is anyone calling for the elimination of
cars?

In the 47 years that we've had nuclear power in the US - we have had
one major accident - Three Mile Island - which did not injure the public.
[ There was major damage to the reactor - but the public was not
injured. The amount of radiation release was trivial ]

[ Some point to Chernobyl. Chernobyl was a flawed design - one that
US scientists pointed out was unsafe to the Soviets - who did nothing.
The operators were running a poorly planned experiment on the
reactor - and then didn't follow the plan. Chernobyl is an anomaly
that bespeaks more about the flawed Soviet system, than it does
about nuclear power as practiced in Western countries.]

When you talk about efficiency - do you mean the thermodynamic
efficiency of converting heat to electricity? In that case, coal plants
are somewhat more efficient because fossil fueled boilers are allowed
to run hotter than we let nuclear reactors run. The hotter the heat
source, the more efficient. However, the comparison between the
two is really "apples and oranges". The heat sources are different.
Might one be a little less efficient with the cleaner nuclear heat
source than a dirtier coal source in order to realize the advantages
of that cleaner nuclear energy source?

Additionally, coal plants put more RADIOACTIVITY into the air than
nuclear plants. Coal contains trace amounts of uranium and thorium.
Because we burn billions of tons of coal - we put thousands of tons of
radioactive uranium and thorium into the air. See the following from
scientists at Oak Ridge National Laboratory:

http://www.ornl.gov/info/ornlreview/rev26-34/text/colmain.html

which states:

"Americans living near coal-fired power plants are exposed to higher
radiation doses than those living near nuclear power plants that meet
government regulations"

As far as nuclear waste is concerned, the amount of nuclear waste
that has accumulated in nearly 50 years of operating nuclear power
plants, as well the waste from the Manhattan Project and defense
uses of nuclear energy - would fit in a volume the size of a high school
gymnasium. That's really trivial compared to the mountains of slag
from coal power plants.

Scientists from our national laboratories and the National Academy of
Sciences say we can safely dispose of nuclear waste in an underground
depository like Yucca Mountain. The opposition is basically political.

The waste can be safely transported to Yucca Mountain. Sandia National
Laboratory has done lots of testing on the casks used to ship the waste,
including putting them on a truck parked across a railroad track, then
putting rockets on a locomotive and slamming it at high speed into the
cask:

http://www.sandia.gov/recordsmgmt/ctb1.html

I think the case for expanded use of nuclear power is well made.

Dr. Gregory Greenman
Physicist

[CharlesP]

Give up nuclear power - see my post on radioactive material.

[russ_watters]

No offense, but your post in the reprocessing thread ignores everything said before it. Its quite simply, wrong.

[CharlesP]

No offense, but your post in the reprocessing thread ignores everything said before it. Its quite simply, wrong.

I keep up with Physics Today and mainline scientists have determined that reprocessing is too hazardous. One Rocky Flats is enough. I doubt that even a Republican government will permit it any time soon. Long term storage is on hold because of contrary reports. This is a very serious impediment to any long term continuation of nuclear power. A survey of previous posts shows that some folks are not doing their homework. Three mile Island demonstrated the same horrible irresponsibility in US power companies that Chernobyl demonstrated in the USSR.

[Morbius]

I keep up with Physics Today and mainline scientists have determined that reprocessing is too hazardous. One Rocky Flats is enough. I doubt that even a Republican government will permit it any time soon. Long term storage is on hold because of contrary reports. This is a very serious impediment to any long term continuation of nuclear power. A survey of previous posts shows that some folks are not doing their homework. Three mile Island demonstrated the same horrible irresponsibility in US power companies that Chernobyl demonstrated in the USSR.

LIAR LIAR LIAR!!!

The Physics community is very supportive of Nuclear Power and has
made no such statement that reprocessing is too hazardous.

If you've been reading Physics Today and you make the statement above,
then either you are a liar or you didn't understand what you read.

Contrary to your assertion above, there is no consensus by "mainline
scientists" that reprocessing is too dangerous.

If anyone is not doing their homework - it is YOU!

There is absolutely NO comparison between Three Mile Island and
Chernobyl. At TMI, the release of radioactivity was trivial - much less
than the natural radioactivity. The containment system worked very
well.

I think the Judge who heard the TMI lawsuits summarized the case very
well when she summarily dismissed the complaints against the utility
which operated TMI:

http://www.pbs.org/wgbh/pages/frontline/shows/reaction/readings/tmi.ht

Judge Sylvia Rambo states:

"Defendants, proffer of evidence and that put forth by Plaintiffs in both
volume and complexity are vast. The paucity of proof alleged in support
of Plaintiffs, case is manifest. The court has searched the record for any
and all evidence which construed in a light most favorable to Plaintiffs
creates a genuine issue of material fact warranting submission of their
claims to a jury. This effort has been in vain. ..Those standards combined
with the scarcity of evidence of record to support Plaintiffs, claims
mandate the result reached by the court today. "

You demonstrate your ignorance further when you try to connect
nuclear power with Rocky Flats. Rocky Flats was a nuclear weapons
facility run by the Government - and doesn't have anything whatsoever
to do with the commercial nuclear power industry.

Dr. Gregory Greenman
Physicist

[Astronuc]

There are some physicists in organizations such as Union of Concerned Scientists and Nuclear Control Institute who actively oppose the use of Nuclear Energy. However, they seem to be in the minority.

As for the premier organization of Physicists, The American Physical Society, please refer to the policy statement 00.3 ENERGY STATEMENT (Adopted by the Council, 19 November 2000), "Energy Policy for the Twenty-first Century", which states -

"The Council of the American Physical Society believes that the use of renewable energy sources, the adoption of new ways of producing and using fossil fuels, increased consideration of safe and cost effective uses of nuclear power, . . . " and yes they do call for energy-efficient technologies. No where to they call forelimination of nuclear energy.

http://www.aps.org/statements/00_3.cfm

BTW - my personal experience in dealing with UCS and NCI is that they sometimes miss the mark or are completely wrong, and some individuals lack sufficient expertise to make credible assertions regarding the consequences of nuclear power.

[CharlesP]

Nuclear power faces three serious challenges even not counting the public mistrust of the industry.
1. Disposal. A recent report on the Yucca site has caused a stir in Congress. Failures which it outlines may cause a serious slip in schedules.

2. Building reactors with safety sufficient to avoid more crises. The present administration has the same attitude as the Rocky Flats management and lowered standards will not help the industry.

3. There is a quickly closing window of opportunity. Unless construction gets underway in a few short years the available funds will evaporate in the expected economic collapse.

[Atom-Go-Boom!]

Hey Guys,
Here's my point of view in the nuclear world:
Nuclear Fission is not very effecient because of the waste its produces. In'till we create a stable, effecient fusion reactor, we will be buried up to our knees in radioactive waste and all die.

[enigma]

As opposed to pumping much more radioactive C-14 into the atmosphere by burning coal, and getting the added benefit of giving everyone asthma?

I think you're seriously overestimating the quantity and seriously underestimating the containability of nuclear waste.

Welcome to the forums, BTW :wink:

[Morbius]

Hey Guys,
Here's my point of view in the nuclear world:
Nuclear Fission is not very effecient because of the waste its produces. In'till we create a stable, effecient fusion reactor, we will be buried up to our knees in radioactive waste and all die.

Atom-Go-Boom,

What about the waste from other forms of power generation?

Because nuclear power plants derive energy from the nuclear force which
is ONE MILLION times more powerful than the Coulomb force on which
chemical reactions - the source of energy for fossil fuels - are based -
pound for pound, nuclear power plants produce one million times more
energy than fossil fuels.


Or to turn that around - for a given amount of energy - nuclear power
produces ONE-MILLIONTH the amount of waste as chemical processes!!

You hear a lot of talk about the nuclear waste problem - but do you have
any idea of the amount of nuclear waste the USA has?

All the nuclear waste - from about 50 years of nuclear power - will fit
in a building the size of the gymnasium at your local high school!!!

The waste from coal plants - a MILLION times as much. A lot of the
waste from coal plants goes into the air for people to breathe -
including the RADIOACTIVITY!!!

Yes - coal has trace amounts of Uranium and Thorium in it. Because we
burn BILLIONS of tons of coal each year - coal plants are putting
THOUSANDS of TONS of radioactive Uranium and Thorium into the air
for you to breathe and be exposed to the radioactivity!!

See the following report from the Oak Ridge National Laboratory:

http://www.ornl.gov/info/ornlreview/rev26-34/text/colmain.html

As the report states, Americans get 100 times the radiation exposure
due to coal as they do from nuclear plants - 100 TIMES!!!

That additional radiation exposure is brought to you by the idiots in the
environmental movement that have opposed nuclear power at every
turn.

Good scientists, like the those in the American Physical Society; have
been trying to get out the message for years that nuclear power is more
friendly to the environment than the alternatives.

http://www.aps.org/statements/93_7.cfm

But I'm afraid it's hard for the American Physical Society and their
official "position papers" to compete with the so-called
"environmentalists" with their "No Nukes" rock concerts.

Dr. Gregory Greenman
Physicist

[Morbius]

Nuclear power faces three serious challenges even not counting the public mistrust of the industry.
1. Disposal. A recent report on the Yucca site has caused a stir in Congress. Failures which it outlines may cause a serious slip in schedules.


Charles,

Why do you only give "part" of the story. Every report to Congress
critical of Yucca Mountain has been thoroughly "shot down" by the
scientists of the National Labs on whom Congress calls for technical
support.

If you would be specific about which report you are referring - I can
tell you specifically what's WRONG with it!



2. Building reactors with safety sufficient to avoid more crises. The present administration has the same attitude as the Rocky Flats management and lowered standards will not help the industry.


Why do keep confusing commercial nuclear power with a defense
program?

You are also LYING when you say the present administration is lowering
standards. There has been absolutely NO lowering of standards for the
nuclear industry! The industry is perfectly able to live with, and thrive
in the current regulations on operating reactors.

Personally, I would make a change from the 2 step to a 1 step licensing
process. At present, there is a whole process of hearings and court
cases when a utility applies for a permit to build the plant. Once the
permit is issued, then the utility can build the plant.

After the plant is built - there's a whole second process hearings and
court cases when the utility applies to operate the plant. This second
step is a rehash of the first step.

A better solution is a single step process - like when you apply to build
a home. Everything is considered and adjudicated BEFORE construction.
Once a decision is made, construction starts, and upon completion - with
a determination by the building inspector that the house was constructed
properly - obeying all building codes and restrictions in the building
permit - you get to move in.

The same should be true for nuclear power plants. Make all the decisions
up front - and if the plant is constructed as per the construction permit -
then allow the utility to operate the plant.

Nuclear power has an enviable safety record - the SINGLE serious
accident in 50 years - Three Mile Island - injured nobody.

Can any other industry make that claim? Take the airline industry.
Airline travel is one of the safest, if not THE safest form of travel - yet
every few years a plane crashes and a couple hundred people are killed.

Or take automobiles. Each and every year 50,000 people are killed by
automobile accidents.

If you really were concerned about saving the lives of the maximum
number of people - THAT'S where you should spend your efforts.


3. There is a quickly closing window of opportunity. Unless construction gets underway in a few short years the available funds will evaporate in the expected economic collapse.

As far as I see - the USA will always have a demand for energy - so
whatever funds the USA is willing to spend on energy generation - are
available to fund nuclear power. There's no impending crisis.

Dr. Gregory Greenman
Physicist

[NEOclassic]

The Uranium-235 that I handled at LANL was truely Weapon-grade - over 90% enriched. Not only that but three crits were the fuel of the so-called "25" gun gadget. I think the enrichment of reactor-grade U-235 was perhaps more like 5% and that means that 95% of the fuel was inert U-238 - or was it? Truth is that U-238 has a 2.7 barn probability of capturing a neutron from the persistent neutron flux in the reactor thus producing, in fairly short order, a couple of beta electrons and a weapons-grade plutonium-239 atom. There are many folk who think that those atoms just sit there awaiting some North Korean to go on an Easter egg hunt and retrieve all that stuff for a Korean Bomb - Recently the press declared that a single spent fuel rod had some 60 pounds Pu-239 - that's about twice the 30.8 pounds of Pu-239 in the US Nagasaki Weapon. Lest the reader forget, that weapons fuel continues for the several weeks or months in that same neutron flux where there is a statistical competition between two main reactions. Some of the Pu-239 atoms do fission but some become Pu-240. Now then what could possibily happen to that Pu-240? It too has its own propensity to fission vs to become Pu-241 and so on and on. Below is a table that shows that more than 90% of the originally created Pu-239 has been burnt with the remaining being mostly Pu-242, and Pu-244. If the reader finds this unbelievable I suggest that he ask google about plutonium-242. After the mid 70s LANL, used real Pu-242 in four-pi full-scale implosion models and they didn't go nuclear.

Pluton- Cross Sections in barns (probabilities) Original Number E+9
ium Neutron, Gamma Neutron, Fission Number Number
Isotope Pu-n> N >Pu-n+1 Pu-n> N >Frags Held Fisssioned
Over
Pu-239 286 barns 742 barns 2.653 E+8 7.347 E+8
Pu-240 250 0.03 2.650E +8 3.2 E+4
Pu-24l 390 1010 7.382 E+7 1.912 E+8
Pu-242 19 2 6.67 E+7 7.0 E+5
Pu-243 170 0 6.6 E+7
Pu-244 1.8 0 7. E+5

Remember that a vast majority of fragments are beta emitters and that there is one, strontium-90 with half life of 29 years that needs to be avoided since it is likely responsible for breast cancer epidemic and two iodine isotope one is so long lived that the intensity is inconsequential and the other is so weak that the problem is the gamma that accompanies the beta emission.
Cheers, Jim Edit! The table above was constructed with 5 columes but it got jammed together. J Edit -2 1st Col if isotope, 2nd is gamma cross section, 3rd is fission CS 4th the the numbr remaining unburnt and the 5th is number burned at each stage. The original sample was E+9 Pu-239 created.

[Morbius]

The Uranium-235 that I handled at LANL was truely Weapon-grade - over 90% enriched. Not only that but three crits were the fuel of the so-called "25" gun gadget. I think the enrichment of reactor-grade U-235 was perhaps more like 5% and that means that 95% of the fuel was inert U-238 - or was it?

Jim,

The enrichment for fresh fuel in U.S. LWRs [ Light Water Reactors - both
Pressurized Water Reactors (PWRs) and Boiling Water Reactors (BWRs)]
is about 3% to 4%.


Truth is that U-238 has a 2.7 barn probability of capturing a neutron from the persistent neutron flux in the reactor thus producing, in fairly short order, a couple of beta electrons and a weapons-grade plutonium-239 atom. There are many folk who think that those atoms just sit there awaiting some North Korean to go on an Easter egg hunt and retrieve all that stuff for a Korean Bomb.

The Pu-239 is, of course, fissile - so if it sits in the neutron flux of the
reactor, it can fission. In fact, about 40% of the energy that you get
from a new fuel assembly during the ~3 years that the assembly spends
in the reactor, comes from fissioning Pu-239 that was created in situ.


- Recently the press declared that a single spent fuel rod had some 60 pounds Pu-239 - that's about twice the 30.8 pounds of Pu-239 in the US Nagasaki Weapon.

The press got that wrong - a single rod doesn't weigh anywhere near
60 pounds. What they probably meant was that the total of ALL the
rods gives you the 60 pounds. The reports that I have read have said
that the North Koreans got enough Pu-239 for about 2 weapons in this
latest batch.


Lest the reader forget, that weapons fuel continues for the several weeks or months in that same neutron flux where there is a statistical competition between two main reactions. Some of the Pu-239 atoms do fission but some become Pu-240. Now then what could possibily happen to that Pu-240? It too has its own propensity to fission vs to become Pu-241 and so on and on. Below is a table that shows that more than 90% of the originally created Pu-239 has been burnt with the remaining being mostly Pu-242, and Pu-244. If the reader finds this unbelievable I suggest that he ask google about plutonium-242. After the mid 70s LANL, used real Pu-242 in four-pi full-scale implosion models and they didn't go nuclear.

The table you give Jim is appropriate for a reactor that is operated
as a power reactor. However, a production reactor - one whose purpose
is to produce weapons grade plutonium is not operated in the same
manner as a power reactor. In a production reactor, you don't leave
the fuel assemblies in the reactor as long as in a power reactor. In fact,
you leave the fuel assemblies in about 1/5 as long.

As you say - once one creates the Pu-239 in the reactor - it is subject to
being fissioned, and to creating the heavier [ and unwanted ] Pu-240 and
Pu-242.

But when you are operating the reactor as a production reactor - you
take the fuel assembly out of the reactor earlier in order to avoid just
the problem you outlined above.

That's the difference between so-called "reactor-grade" Plutonium and
"weapons-grade" Plutonium. You get "reactor-grade" Plutonium from
a reactor that was operated as a power reactor and the fuel was
subjected to a high "burnup". When you operate the reactor as a
production reactor, such that the fuel is subjected to low "burn-up",
then you get "weapons-grade" Plutonium.

I'm not sure what the point you were trying to make was - but one most
certainly can get "weapons-grade" Plutonium if one has a reactor, and
knows how to operate it to maximize the amount of weapons usable
Plutonium produced.

Dr. Gregory Greenman
Physicist

[NEOclassic]

Thanks Gregory,
I am aware that the total time in the reactor has a lot to do with production. My main emphasis here was meant to show that whatever Plutonium that remained after retirement from a power reactor would statistically be mostly 242 and 244 and useless as weapon fuel. Cheers, Jim

[kapton]

One problem with fission is;
If a high powered neutron flux pulse gun fired N's at u235 then;
the initial wave of neutrons would fission the initial surface of the u235. However as the energy expands and increases, especially multiplies in small areas where fission is commonley exerting, then the energy will combine and wipe out the N and carry the uranium material away, dissallowing for a highly efficient neutron fission of the entire core. what i mean is that the speed of combining nuclear fission carries across an area much faster that a neutron takes to combine with a nucleus and fission. so therefor increasing the density of the uranium in not always going to work in greater power? Also are the neutrons kinetic?. because the binding energy of a nucleus is enough to fission pu239, u235 and u233. but u238 and th232 require kinetic N's.???

so chain reaction is a problem here?

[Morbius]

Thanks Gregory,
I am aware that the total time in the reactor has a lot to do with production. My main emphasis here was meant to show that whatever Plutonium that remained after retirement from a power reactor would statistically be mostly 242 and 244 and useless as weapon fuel. Cheers, Jim

Jim,

Your final statement is incorrect.

Nuclear weapons scientists conducted a nuclear test in 1962 to show
that you CAN make nuclear weapons with reactor grade plutonium.

In fact, I believe it was your former employer, Los Alamos, that conducted
this test. This fact has been known to nuclear weapons designers since
the 1960s - but was only declassified in July 1977.

Courtesy of the U.S. Department of Energy:

http://www.osti.gov/html/osti/opennet/document/press/pc29.html

which states specifically:

"A successful test was conducted in 1962, which used reactor-grade
plutonium in the nuclear explosive in place of weapon-grade plutonium.

The yield was less than 20 kilotons."


There's more Pu-239, and not as much Pu-240 and Pu-242, as you think
in reactor grade plutonium. The point is that, althought tricky; you
CAN make a weapon from reactor grade plutonium.

Dr. Gregory Greenman
Physicist

[cwbiii]

Nuclear power is generally as safe as those in charge of operating it. The proceedures are in place to operate it safely. Problems happen when the operating agencies (power companies) try to cut corners by hiring high school grads and train them to operate them as a cost saving measure. I once held an operators license for an open pool research reactor... it took quite a bit of work to get there, and the work needed to operate a power reactor is quite a bit more. Attention to detail is a necessity.
Actual operation is very boring... watching guages and readouts while making tiny adjustments to the control rods from time to time.

[russ_watters]

Nuclear power is generally as safe as those in charge of operating it. The proceedures are in place to operate it safely. Ideally, it's even safer than that: newer reactors are truly "idiot proof" - it would take a conscous effort to cause an "accident." One feature used in Navy reactors, for example, is magnetic support for the control rods. If the plant malfunctions and power is lost, the rods drop into the reactor on their own and stop the reaction.

Pebble-bed reactors, iirc, are physically incapable of meltdown.

Reactor safety really is extrordinarily high.

[Morbius]

Ideally, it's even safer than that: newer reactors are truly "idiot proof" - it would take a conscous effort to cause an "accident." One feature used in Navy reactors, for example, is magnetic support for the control rods. If the plant malfunctions and power is lost, the rods drop into the reactor on their own and stop the reaction.


Russ,

I think you'll find that magnetic support of control rods is universal for
ALL reactors that have control rods that enter from the top - and drop
down into the core.

For example, see the following URL courtesy of the M.I.T. Nuclear Reactor
Laboratory:

http://web.mit.edu/nrl/www/reactor/core_description.htm

In the first photo of the core, the caption reads:

"The electromagnets used to "scram" the reactor can be seen in the
upper areas of the photo."

Those shiny discs that surround the rod followers - a good example
is seen at the top edge of the photo at about the 11:30 o'clock position;
are the electromagnets that when de-energized will cause the control
rods - or blades, in the case of the M.I.T reactor; to drop into the core
by gravity.

The only reactors that do not use electromagnets to support the control
rods are BWRs - Boiling Water Reactors. BWR control rods enter from
the bottom of the reactor vessel, and have to be pushed UP in order to
scram the reactor. This is ensured by using the pressure of the water
inside the reactor to drive the piston that drives the control rod.

Dr. Gregory Greenman
Physicist

[rdt2]

The problem with nuclear power (and, Dubya, it's 'nu-clear' not 'noo-kyu-lar') is more political than technical. A largely innumerate public (I'm in the U.K but it's probably true worldwide) have no concept of risk and will always fall for the 'Chernobyl' argument. However, that same public is unlikely to want to accept the drastic change of lifestyle that will come if we don't develop nuclear power. Whether one likes it or not, it's coming. Most of our respective politicians simply won't admit it.

[Morbius]

The problem with nuclear power (and, Dubya, it's 'nu-clear' not 'noo-kyu-lar') is more political than technical. A largely innumerate public (I'm in the U.K but it's probably true worldwide) have no concept of risk and will always fall for the 'Chernobyl' argument. However, that same public is unlikely to want to accept the drastic change of lifestyle that will come if we don't develop nuclear power. Whether one likes it or not, it's coming. Most of our respective politicians simply won't admit it.

rdt2,

Yes - it always amazes me that people can be so phobic about nuclear
power; claiming that they are afraid of some fantasy accident concocted
by the anti-nuclear crowd; yet they still fly on airliners!

Several years ago, the PBS show "Frontline" did a show about nuclear
power entitled "Nuclear Reaction" hosted by Pulitzer Prize-winning
author Richard Rhodes. At on point, Frontline interviewed a psychiatrist
concerning the anti-nukes. He states that they are not so much
anti-nuclear; but anti-technology and anti-business. Courtesy of
PBS "Frontline":

http://www.pbs.org/wgbh/pages/frontline/shows/reaction/interviews/dupont.html

Dr. Gregory Greenman
Physicist

[theCandyman]

I am puzzled even more that while these people are aginst nuclear power, they would most likely not want to give up the benefits of nuclear technology.

[Morbius]

I am puzzled even more that while these people are aginst nuclear power, they would most likely not want to give up the benefits of nuclear technology.

Candyman,

I think they would forego the benefits of nuclear technology.

As the good Dr. DuPont states in his interview linked above; the anti-nuclear
crowd is really an anti-technology crowd.

For them, technology is a scourge upon the planet. Many of them look to
the lifestyles of the Native Americans of a few hundred years ago. They
believe that theirs is/was the one true way that humankind should exist
in harmony with Nature.

They believe that Man should eeke out a primitive agrarian existence -
and not have all the technology that you and I, and many others want.

Frequently, the lifestyles of Native Americans is portrayed in a
"romantic" fashion; without the downsides. People tend to forget that
without our technology; we humans are just another animal on the face
of the planet - and subject to all the harsh realities of life as an animal -
disease, hunger from crop failure, ...

I think we live a much better and longer life today that would be the
envy of any peoples of the past. That's why people developed all this
technology that we have today - to rid us of the strife of the past.

However, in order to continue the lifestyles that the advanced countries
enjoy, and to spread the benefits to those that live in the more primitive
areas of the world; is going to take energy. Energy fuels our modern
technological lifestyle - and it will take more energy for the spread
of a modern lifestyle to the poorer nations of the world.

Nuclear energy holds the promise of being able to deliver the energy
needed. Those that want to turn back the clock and have us live a more
primitive life; know that by opposing nuclear power - they can put a
monkey wrench into the engine that drives the expansion of advanced
technological lifestyles.

By strangling nuclear power, they hope to win the war against technology
and leave us no choice but to pursue their dreams of a primitive culture.

Dr. Gregory Greenman
Physicist

[rdt2]

As the good Dr. DuPont states in his interview linked above; the anti-nuclear crowd is really an anti-technology crowd.

For them, technology is a scourge upon the planet. Many of them look to
the lifestyles of the Native Americans of a few hundred years ago. They
believe that theirs is/was the one true way that humankind should exist
in harmony with Nature.

They believe that Man should eeke out a primitive agrarian existence -
and not have all the technology that you and I, and many others want.

Frequently, the lifestyles of Native Americans is portrayed in a
"romantic" fashion; without the downsides....

Indeed so. The first paragraph of http://www.mech.gla.ac.uk/~rthomson/teaching/lecnotes/ch01.htm might strike a chord.

[russ_watters]

rdt2,

Yes - it always amazes me that people can be so phobic about nuclear
power; claiming that they are afraid of some fantasy accident concocted
by the anti-nuclear crowd; yet they still fly on airliners! It does not amaze me (am I too young to be that cynical?). People are afraid of the unknown and most people know little to nothing about the real risk. Ask people how many people died in Chernobyl and the answers you get are in the hundreds of thousands. A lot of the blame goes to the media - they can't pass up a good scare story. Several years ago, the PBS show "Frontline" did a show about nuclear
power entitled "Nuclear Reaction" hosted by Pulitzer Prize-winning
author Richard Rhodes. At on point, Frontline interviewed a psychiatrist
concerning the anti-nukes. He states that they are not so much
anti-nuclear; but anti-technology and anti-business. Those would be the so-called "environmentalists". I don't know how big of a group they really are, but they are the ones who are actively anti-nuclear. They are neo-hippies and they are pretty much anti-everything modern. This is the dangerous group as they are able to convince the larger ignorant and impressionable group (described above) of things like 100,000 people died as a result of Chernobyl.

(great link, btw)

[Morbius]

It does not amaze me (am I too young to be that cynical?). People are afraid of the unknown and most people know little to nothing about the real risk. Ask people how many people died in Chernobyl and the answers you get are in the hundreds of thousands. A lot of the blame goes to the media - they can't pass up a good scare story. Those would be the so-called "environmentalists". I don't know how big of a group they really are, but they are the ones who are actively anti-nuclear. They are neo-hippies and they are pretty much anti-everything modern. This is the dangerous group as they are able to convince the larger ignorant and impressionable group (described above) of things like 100,000 people died as a result of Chernobyl.

(great link, btw)

russ,

One problem seems to be that a lot of the entertainers fall into this
group - hence we have the "No Nukes" concert, etc.

The problem is, as you state above; that the small group can convince
the larger "ignorant and impressionable" group.

For me - the answer to ignorance is education. There too we have a
problem - the quality of education in our schools.

A little anecdote; each year I help out at our local "Expanding Your
Horizons" conference - an annual one day workshop for junior and
senior high girls that showcases women scientists and engineers as role
models.

One of the health physicists at the Lab [ they're the people that ensure
that radiation and radioactivity are handled properly ] had a display
of items that you would find around the house that are radioactive -
smoke detector, fossils, pottery... [ One of the largest radioactive
sources in your house is probably that 50mm lens on the front of your
Nikon, Minolta, or Canon SLR camera as I learned from his display.
Optical glass has thorium in it.]

He told me he also took his little show "on the road" to local [ Bay area ]
schools. At one high school, he was demonstrating the radioactivity in
a fossil shark's tooth. The science teacher asked him what he did to
make the shark's tooth radioactive.

He replied, "Nothing!" and explained that 100 years ago when the shark
was alive and swimming in the ocean, it was injesting the sea water,
removing the minerals from the water, and those minerals were used to
grow the shark's teeth. Some of those minerals are salts of uranium and
thorium - hence they are radioactive.

The high school science teacher asked, "You say that shark's tooth is
100 years old?" He told her, "That's right!". To which she responded,
"Well if that shark's tooth is 100 years old, how could it be radioactive;
since Man didn't invent radioactivity until 1945?"

I was aghast. Somewhere in the Bay Area is a high school science teacher
that is teaching her high school students that Man invent radioactivity
in 1945!!!

What we need are good teachers that can give our students a good
education. When a well educated person hears one of these "scare
stories"; they will be educated enough to see the inconsistencies and the
untruths of the "scare story" and not believe it.

That's how you immunize people against "scare story" propaganda.

I might also add that online forums like this one are also a part of the
education process - so keep up the good work!!

Dr. Gregory Greenman
Physicist

[Morbius]

l.
(great link, btw)

Russ,

If you like that one - also check out one of the other interviews; one with
Dr. Charles Till, former Associate Director of Argonne National Lab:

http://www.pbs.org/wgbh/pages/frontline/shows/reaction/interviews/till.html

Dr. Till was one of my bosses 20 years ago when I was at Argonne and
working on the Integral Fast Reactor [ IFR ] that he describes.

Dr. Gregory Greenman
Physicist

[russ_watters]

The high school science teacher asked, "You say that shark's tooth is
100 years old?" He told her, "That's right!". To which she responded,
"Well if that shark's tooth is 100 years old, how could it be radioactive;
since Man didn't invent radioactivity until 1945?"

I was aghast. Somewhere in the Bay Area is a high school science teacher
that is teaching her high school students that Man invent radioactivity
in 1945!!! I think I'm going to vomit.

I visited Limerick when I was a cub scout (I still live about 15 miles away). I think it should be a part of the curriculum in whatever grade a child is first exposed (pun intented) to radiation (8th or 9th?) that they visit a plant if one is within field-trip range.

[theCandyman]

How does someone like that come into a teaching job!?

Yes, education at an early age is probably the best way to prevent them from actually listening to the propaganda about nuclear power and the like, but for that there is a need for people who would want to teach younger children and know sufficient material.

[Astronuc]

How does someone like that come into a teaching job!?

Because primary or public school teachers are not necessarily trained (or at least rigorously that is) in the the subject that they teach. Instead they get a degree in education, and consequently many (most?) math/science teachers get little experience in rigorous math, science and engineering courses.

There are exceptions. My chemistry teacher in HS (30+ years ago) had a Master of Science Degree in Chemistry. One of the Physics teachers had a PhD from Caltech, but he only stayed for two years, then went to work for Shell R&D.

Currently, one of the Chemistry (Science) teachers at my daughter's high school is a retired chemist/chemical engineer from one of the development labs of a large oil company.

The American Nuclear Society and DOE/National Labs have outreach programs.

[Morbius]

Because primary or public school teachers are not necessarily trained (or at least rigorously that is) in the the subject that they teach. Instead they get a degree in education, and consequently many (most?) math/science teachers get little experience in rigorous math, science and engineering courses.

Astronuc,

Yes - several years ago, a colleague of mine took an early retirement and
wanted to teach high school Algebra.

He was a Ph.D. in Physics - and could have taught at the University level.

However, he couldn't teach high school Algebra until he went back to
school and studied education in order to get his teacher's certification.

Dr. Gregory Greenman
Physicist

[rdt2]

Astronuc,

Yes - several years ago, a colleague of mine took an early retirement and
wanted to teach high school Algebra.

He was a Ph.D. in Physics - and could have taught at the University level.

However, he couldn't teach high school Algebra until he went back to
school and studied education in order to get his teacher's certification.

Dr. Gregory Greenman
Physicist

And quite right too! Having a PhD is no guarantee of being a good schoolteacher. In fact, having a PhD and being a hotshot researcher is no guarantee of being a good university teacher.

[ohwilleke]

I think I'm going to vomit.

I second that thought. One reason people like this get their jobs is that there is a shortage of math and science teachers. Often they get people who aren't certified in the area.

Now, I agree with the point about certification being a problem that Mobius pointed out. There is a problem with people who have the content knowledge being unable to teacher due to lack of teacher's education courses, which are often dismal in quality. Professors teaching undergrads do just fine without them (although a happy medium between throwing people into teaching with no instruction about teaching, and throwing people into teaching with huge numbers of useless education courses, seems possible).

But, too often, certification of some kind overtakes subject area knowledge. It is easier to be an English teacher and get reassigned to teaching science when there is a shortage, than to be a scientist or engineer and get assigned to teaching science when there is a shortage.

[ohwilleke]

I am puzzled even more that while these people are aginst nuclear power, they would most likely not want to give up the benefits of nuclear technology.

I disagree with the notion that most people who are anti-nuclear are anti-technology. There is a group that is, but there is a far larger group that is not.

Also, while there is definitely an exaggerated fear of the risks of nuclear technology, the bigger problem in my mind is a lack of knowledge of the risks of non-nuclear technology to compare the risks of nuclear technology to.

Chernobyle is exaggerated. But, I don't think that there is anyone who would disagree that it was a bad thing that killed people. Likewise, while the actual harm caused by Three Mile Island was modest, I don't think anyone would disagree that the world would have been a better place if it hadn't happened. Nuclear engineers exist primarily to make sure that things like that don't happen.

The problem comes in when people analyze risk. They say, hmmm. . . there is bad stuff that happened when people used nuclear power, better stay with the status quo, instead of saying: There is bad stuff that happens with every kind of power, how bad is each?

If people had a better grasp of just how horribly dangerous coal fired power generation was on a life cycle basis, from mining accidents and black lung to environmental damage to habits and communities caused by coal mining, to transportation accidents caused when a much larger volume of fuel is moved, to accidents within coal fired plants, to illnesses caused by coal fired plant waste and emissions (and the talley isn't much better for the rare oil based plant, although natural gas is significantly better than either coal or oil, but quite expensive), I think a lot more people would appreciate the benefits of nuclear power and be less afraid.

But, most proponents of nuclear power don't really grasp that they need to educate people about coal even more than they do about nuclear power, if they want to make their point clear. They are busy educating people about nuclear power and then don't understand why people don't reach the same conclusion that they do.

[Moonbear]

I think I'm going to vomit.

I visited Limerick when I was a cub scout (I still live about 15 miles away). I think it should be a part of the curriculum in whatever grade a child is first exposed (pun intented) to radiation (8th or 9th?) that they visit a plant if one is within field-trip range.

I agree, as a teen I visited the Oyster Creek plant. Though, I was disappointed we didn't really get to see much of the actual plant, but it remained a valuable opportunity to learn a little from the experts.

One problem I recall from when I was young is that the one environmental hazard of the Oyster Creek plant was the water being dumped back into the river there that had been used to cool the reactor wound up warming the river temperature such that it changed the ecosystem. My parents used to have a boat docked along that river and all the boat owners had to move their boats to another location because some sort of worms or something were proliferating in the warmer water and destroying the hulls of the boats (back in the days of wooden boats). I really don't know much about it, just what my parents told me of having to move their boat (I was too young, though do remember vaguely moving to a new marina and being excited it had showers because it meant not having to bathe out of a bucket of cold water when we spent the night on the boat).

Anyway, just wondering if this is still an issue, or if plants have been modified to allow that water to cool more before being dumped back into rivers?

[Morbius]

I disagree with the notion that most people who are anti-nuclear are anti-technology. There is a group that is, but there is a far larger group that is not.

Also, while there is definitely an exaggerated fear of the risks of nuclear technology, the bigger problem in my mind is a lack of knowledge of the risks of non-nuclear technology to compare the risks of nuclear technology to.

Chernobyle is exaggerated. But, I don't think that there is anyone who would disagree that it was a bad thing that killed people. Likewise, while the actual harm caused by Three Mile Island was modest, I don't think anyone would disagree that the world would have been a better place if it hadn't happened. Nuclear engineers exist primarily to make sure that things like that don't happen.

The problem comes in when people analyze risk. They say, hmmm. . . there is bad stuff that happened when people used nuclear power, better stay with the status quo, instead of saying: There is bad stuff that happens with every kind of power, how bad is each?

ohwilleke,

Look at the comparison between nuclear power and airline travel.

Nuclear power has had one major accident in the USA, in nearly half
a century of using nuclear power. That one accident didn't kill anyone,
exposed the public to a minimal amount of radiation [ less than flying
in an airliner ]. The impact on the public was minimal; although the
utility took a substantial financial hit.

Now compare that to airline travel. In the last half century, there have
been quite a few major airliner crashes. These crashes have killed on
the order of a hundred people per crash, or there abouts. Flying in an
airliner subjects one to more radiation in a few hours than one gets
all year due to nuclear power.

Are there people protesting at airports? Do people want to shutdown
an industry that kills a couple hundred people every 2 to 3 years?

Of course airline travel is comparitively safe - especially when compared
with automobiles. The use of automobiles in the USA kills almost
50,000 people annually.

Where are the people protesting cars? Where are the people protesting
airlines? There aren't any. People are not afraid of travel in either
cars nor airliners [ some are, but not in general ].

However, they are scared by the nebulous fantasies of nuclear accidents.
The anti-nukes have somehow scared the public into believing that there
is a some catastrophe out there ready to strike. It will be a calamity
when it does - but it just hasn't happened yet - but when it does it will
be really, really BAD!!

Somehow people buy into the scare-monger's vision over what the
actual history of the industry is. That's what I don't understand.


But, most proponents of nuclear power don't really grasp that they need to educate people about coal even more than they do about nuclear power, if they want to make their point clear. They are busy educating people about nuclear power and then don't understand why people don't reach the same conclusion that they do.

I quite frequently point out to those that are so phobic about the
radiation from nuclear power plants - that it PALES compared to what
the coal plants are putting out:

http://www.ornl.gov/info/ornlreview/rev26-34/text/colmain.html

Dr. Gregory Greenman
Physicist

[motai]

One problem I recall from when I was young is that the one environmental hazard of the Oyster Creek plant was the water being dumped back into the river there that had been used to cool the reactor wound up warming the river temperature such that it changed the ecosystem.

...

Anyway, just wondering if this is still an issue, or if plants have been modified to allow that water to cool more before being dumped back into rivers?

I know that the warm water coming from the nuclear plant at Crystal River is used by the local endangered manatees during the winter in Florida. It is helping them in a sense, so im not sure that such a rule could apply to all reactors.

[Astronuc]

Anyway, just wondering if this is still an issue, or if plants have been modified to allow that water to cool more before being dumped back into rivers?The problem is thermal pollution.

The Rankine thermodynamic cycle is approximately 33% efficient at the operating conditions of commercial nuclear reactors. This means that one has to eliminate 66% (2/3's) of the heat to the environment (the ultimate heat sink). The waste heat can be rejected to the air via cooling towers or into a body of water such as a lake or river.

The problem with the latter, is that the lake or river water can become much warmer than Nature would allow without the presence of a power plant.

Thermal pollution is an environmental issue with the Indian Point Nuclear Plant on the Hudson River, approximately 35 miles north of NY City. HOWEVER, thermal pollution of a lake or river is a problem regardless of the primary source of heat, be it fossil, e.g. coal, oil or gas, or nuclear. So, i.e. it is not a problem exclusive to nuclear energy. In parts of the country, as in the south, much of the energy is provide by coal burning plants.

To combat the thermal pollution, cooling towers may be built to reject more heat to the air (atmosphere). However, cooling towers add to the capital cost of the plant (i.e. less profit in a mature plant).

BTW - At Crystal River, unit 3 is nuclear, but units 1, 2 and 4, 5 are coal-burning.

[Morbius]

I agree, as a teen I visited the Oyster Creek plant. Though, I was disappointed we didn't really get to see much of the actual plant, but it remained a valuable opportunity to learn a little from the experts.

One problem I recall from when I was young is that the one environmental hazard of the Oyster Creek plant was the water being dumped back into the river there that had been used to cool the reactor wound up warming the river temperature such that it changed the ecosystem.

Anyway, just wondering if this is still an issue, or if plants have been modified to allow that water to cool more before being dumped back into rivers?

Moonbear,

For one thing - the fossil-fueled power plants also produce thermal
pollution - although to a somewhat smaller extent.

As Astronuc pointed out, the Rankine cycle of a nuclear power plant
is about 33% efficient. That means 67% of the heat energy produced
by the reactor is dumped into the water as heat, when the river or
lake water is used to cool the plant's condensors.

The same thing happens in a fossil plant. However, the boiler in a
fossil plant operates at a higher outlet temperature than the reactor.
The fossil plant is about 40% efficient - so you only have to dump 60%
of the heat energy produced by the boiler into the lake or river.

So the thermal pollution is 67% for the nuclear power plant and 60%
for the fossil-fuel plant. So the nuclear power plant produces a little
less than 12% more thermal pollution than a fossil plant of equivalent
size.

The way to eliminate the thermal pollution of the lake or river is by
the use of cooling towers - those great big hyperbolic towers that seem
to be the uniquely associated with nuclear power plants [ like Three
Mile Island ]. The cooling towers dump the waste heat directly into the
atmosphere.

Although the cooling towers are seen as a symbol of nuclear power -
they don't have anything to do with the reactor - just the steam cycle.
One could put these same cooling towers on a fossil-fueled boiler plant
as well.

So whenerver you see those big towers - like at Three Mile Island - you
know that the plant is NOT thermally polluting the river or lake.

Dr. Gregory Greenman
Physicist

[ohwilleke]

ohwilleke,

Look at the comparison between nuclear power and airline travel.

Nuclear power has had one major accident in the USA, in nearly half
a century of using nuclear power. That one accident didn't kill anyone,
exposed the public to a minimal amount of radiation [ less than flying
in an airliner ]. The impact on the public was minimal; although the
utility took a substantial financial hit.

Now compare that to airline travel. In the last half century, there have
been quite a few major airliner crashes. These crashes have killed on
the order of a hundred people per crash, or there abouts. Flying in an
airliner subjects one to more radiation in a few hours than one gets
all year due to nuclear power.

Are there people protesting at airports? Do people want to shutdown
an industry that kills a couple hundred people every 2 to 3 years?

Of course airline travel is comparitively safe - especially when compared
with automobiles. The use of automobiles in the USA kills almost
50,000 people annually.

Where are the people protesting cars? Where are the people protesting
airlines? There aren't any. People are not afraid of travel in either
cars nor airliners [ some are, but not in general ].

However, they are scared by the nebulous fantasies of nuclear accidents.
The anti-nukes have somehow scared the public into believing that there
is a some catastrophe out there ready to strike. It will be a calamity
when it does - but it just hasn't happened yet - but when it does it will
be really, really BAD!!

Somehow people buy into the scare-monger's vision over what the
actual history of the industry is. That's what I don't understand.

I would dispute your characterization of how people view the airline industry. In fact, the public does insist on far greater regulation of the airline industry than it does have any other form of transportation. For example, if we had the equivalent of air traffic control for boats, there would be hundreds of lives saved every year. Every airline accident is routinely investigated by the federal government, and airlines are much more likely to be held liable for trivial negligence than someone driving a car.

Indeed, concern about airline safety expressed in lawsuits, has pretty much wiped out the general aviation industry. When, as in that case, the danger level was roughly equivalent to cars, juries, who are just members of the public after all, wiped out the manufacturers and everyone else in sight. The more familiar and better understood the risks are (and the more that people are personally taking the risks rather than entrusting someone else to take them for them) the more people are willing to tolerate the risk, even if the actual risk is higher.

Also, there is a piece of Murphy's law asserting itself. Anything that can go wrong will. The question in the eyes of the public is what can go wrong, and what the worst case scenario is. The largest number of people killed in an airplane also lags just a few years behind the capacity of the largest airplane in service. Ditto ships. People are more afraid of events that kill lots of people at once, than of events that kills small numbers of people frequently.

Coal kills lots of people, but rarely kills as many in one incident as Cherynoble did. Likewise car accidents kill lots of people, but rarely in one incident.

People, maybe down to a hard wiring point, tend to evaluate danger in inaccurate ways such as maximum rather than average number of people killed.

[Moonbear]

HOWEVER, thermal pollution of a lake or river is a problem regardless of the primary source of heat, be it fossil, e.g. coal, oil or gas, or nuclear. So, i.e. it is not a problem exclusive to nuclear energy.

Okay, I guess I only heard of it in the context of nuclear power plants because it was something new that changed a river in my lifetime, and affected people I know, so I actually heard the stories about it. And from yours and Morbius' posts, it sounds like nuclear plants have actually found other ways to deal with it, whereas fossil fuel plants haven't. I'm not crazy enough to think there is any way to provide all the energy we demand without some environmental impact, I just like being aware of what that impact is.

[Astronuc]

Morbius brought up a good point.

Coal and oil plants can obtain efficiencies of up to 40% with Rankine cycle, because they can operate with superheated steam at higher temperatures and pressures. The temperatures and pressure are restricted in nuclear plants primarily for 'safety' reasons.

On the other hand, high temperature gas cooled reactors were expected to get up to 39-42% thermal efficiency. Four plants representing 8 units were planned, but none built, due to the collapse of the nuclear industry - post TMI. I say collapse, because according to the original plans of the industry, over 200 nuclear units had been planned for the US market prior to 1979. Orders were quickly cancelled in the wake of TMI-2's accident.

Furthermore, combined cycle plants based on aero-derivative gas turbines (based on jet engines) which dump their waste heat into steam cycle can get up to 60-62% thermal efficiency, so they waste only 38-40% of the heat. These plants generally tend to be peaking units and use natural gas which has become more expensive as demand for it increases.

[hitssquad]

it sounds like nuclear plants have actually found other ways to deal with it, whereas fossil fuel plants haven't.No. Both coal power plants and nuclear power plants can use cooling towers. This is the Ferrybridge (coal) Power Station:
http://www.freefoto.com/browse.jsp?id=13-32-0

As you can see, it is equipped with cooling towers.

[Moonbear]

No. Both coal power plants and nuclear power plants can use cooling towers. This is the Ferrybridge (coal) Power Station:
http://www.freefoto.com/browse.jsp?id=13-32-0

As you can see, it is equipped with cooling towers.

Thanks for clarifying that point.

[Morbius]

Coal kills lots of people, but rarely kills as many in one incident as Cherynoble did. Likewise car accidents kill lots of people, but rarely in one incident.

ohwilleke,

A single airliner crash kills more people than Chernobyl did.

Dr. Gregory Greenman
Physicist

[ohwilleke]

ohwilleke,

A single airliner crash kills more people than Chernobyl did.

Dr. Gregory Greenman
Physicist

It depends on how you count. If you count only the 31 people who died in the first few weeks, and you have a pretty large airliner, yes. If you make some reasonable inferences about life time effects from the pollution impact of the disaster, I think this is a hard proposition to support.

It noted also that in addition to the immediate deaths from radiation about 209 people suffered acute radiation syndrome. http://www.nea.fr/html/rp/chernobyl/c05.html This will likely have a strong long term impact on these acutely affected individuals. Eleven of them have died since then.

The OECD report ( www.nea.fr/html/rp/chernobyl/welcome.html )notes the increase in cancer incidence among people who lived in the former Soviet Union (i.e. fairly close to the site) a group of people who numbered in the hundreds of thousands in the "highly contaminated territories." Overall its estimate of deaths from late cancer effects, as well as more immediate effects, is in the vincinity of 700-900 deaths at the conservative end of the scale, with non-fatal illnesses affecting thousands of people, and hundreds of thousands of people experiencing forced relocation and/or serious psychological traumas. http://www.nea.fr/html/rp/chernobyl/c05.html

A UN report ( www.chernobyl.info/resources/undpReport10_2_02.pdf ) puts the increase in thyroid cancer deaths at about 2,000 and estimates that could grow to 8,000-10,000, while stating that there is not a consensus on the cancer impact in other types of cancers.

The Chernobyl accident will probably end up killing more people than the worst ever airplane crash (a collision of two 747s on a runway on March 27, 1977 in the Canary Islands that killed 583 people), and certainly more than an average one which kills 75-230 people, and will have an overall impact many times as severe. It isn't killing tens of thousands of people, but its significant health and human impact shouldn't be understated either. The only single incident industrial accident in recent history which comes close in terms of mortality and overall impact is the worse Bhopal chemical plant disaster in India.

By comparison, the worst ever mine disaster in the U.S. (in Monongah, West Virginia on December 6, 1907) killed 361 people. In direct deaths an oil pipeline explosion in Nigeria on October 17, 1998 that killed more than 700, a gas pipeline explosion in Ufa, Asha, USSR on June 3, 1989 that killed more than 650 people, the Salang Tunnel explosion in Afghanistan on November 2, 1982 that killed more than 1,000, an accidental dynamite exposion in Cali, Columbia on August 7, 1956 that killed 1,100 people, and an explosion in the Bombay, India harbor on April 14, 1944 that killed 700 people, come close, but none of these accidents had comparable collateral effects.

Chernobyl will end up killing as many people as some of the worst industrial accidents in history, while having the non-deadly environmental impacts of a major oil spill.

The fact that there have been dozens of major oil spills and numerous major industrial accidents in the history of the fossil fuel industry, at gas pipelines, oil pipelines, coal mines and more, still supports the conclusion that nuclear energy is safer by comparison. But, to reduce the harm caused by Chernobyl to the 31 people who died in short order, is to drastically understate the mortality effects of that disaster.

[russ_watters]

A UN report ( www.chernobyl.info/resources/undpReport10_2_02.pdf ) puts the increase in thyroid cancer deaths at about 2,000 and estimates that could grow to 8,000-10,000, while stating that there is not a consensus on the cancer impact in other types of cancers. The report (page 52) says 6-8,000 cases, not deaths. Thyroid cancer has a relatively low fatality rate (not sure what it is in the former eastern bloc countries and didn't see it in the report). And for the sake of comparison to the US (for assessing the risk to us), the fatality rate is even lower here (roughly 5%) because of better healthcare and in addition getting the cancer in the first place can be prevented by simple things such as iodized salt.

Frankly, I consider long-term death projections to be a little bit sketchy though.

[Morbius]

I

The fact that there have been dozens of major oil spills and numerous major industrial accidents in the history of the fossil fuel industry, at gas pipelines, oil pipelines, coal mines and more, still supports the conclusion that nuclear energy is safer by comparison. But, to reduce the harm caused by Chernobyl to the 31 people who died in short order, is to drastically understate the mortality effects of that disaster.

ohwilleke,

I'm not claiming the 31 short-term fatalities as the total number. [ In
fact, I didn't even quote a number ].

I'm refering to a fairly recent report from the National Academies.
Since it has been nearly 3 decades since the accident - practically all
the cancers and other latent effects will have already manifested
themselves. Although I can't recall the specific numbers at present;
they were less than what one would expect from a single serious
airline accident.

Additionally, Chernobyl is an anomally - not characteristic at all of
the experience of nuclear power in this nation and others.

Nobody is contemplating building a reactor like Chernobyl that is
unstable. Nobody is contemplating performing an ill-designed
experiment on the reactor. Nobody is contemplating disabling all
the safety systems when performing such an experiment.

Since nobody is contemplating doing anything remotely like the
Chernobyl scenario - it will continue to be an anomally.

Dr. Gregory Greenman
Physicist

[theCandyman]

I just had a lecture about Chernobyl today. I am glad, for once I know what you are discussing. And are they any records to compare cancer patients before the accident to afterward?

[hitssquad]

The Chernobyl accident [...] isn't killing tens of thousands of people--
The best judgment of the International Commission on Radiation Protection (ICRP) is that even for low-level radiation, deaths due to cancer occur at a rate of 0.04 per person-sievert (400 per million person-rem). There is little dispute over the collective exposure to the population of the European community and the (former) USSR as 600,000 person-Sv. The cancer deaths are thus likely to be 24,000 [....]
--
http://www.fas.org/rlg/ljan99.html

[Morbius]

--
The best judgment of the International Commission on Radiation Protection (ICRP) is that even for low-level radiation, deaths due to cancer occur at a rate of 0.04 per person-sievert (400 per million person-rem). There is little dispute over the collective exposure to the population of the European community and the (former) USSR as 600,000 person-Sv. The cancer deaths are thus likely to be 24,000 [....]

hitssquad,

Such predictions are based on the old linear no-threshold extrapolation.

However, more recent research indicates that this model grossly over-
predicts radiation mortality.

Because the human body has a radiation-damage repair mechanism -
the no-threshold assumption is very questionable. At low-level doses,
the body repairs the damage. In fact, low-level doses of radiation
actually appear to be protective - as they stimulate the cellular
radiation response.

The radiation-damage repair mechanism is looking more and more
like the body's immune system. Courtesy of LLNL:

http://www.llnl.gov/str/JulAug03/Wyrobek.html

Dr. Gregory Greenman
Physicist

[brewnog]

Three cheers for Ferrybridge! Hip hip.....?

[Moonbear]

The report (page 52) says 6-8,000 cases, not deaths. Thyroid cancer has a relatively low fatality rate (not sure what it is in the former eastern bloc countries and didn't see it in the report). And for the sake of comparison to the US (for assessing the risk to us), the fatality rate is even lower here (roughly 5%) because of better healthcare and in addition getting the cancer in the first place can be prevented by simple things such as iodized salt.

Frankly, I consider long-term death projections to be a little bit sketchy though.

The reason the thyroid is a target organ is that it rapidly concentrates iodine (thyroid hormones contain iodide). If you ingest cold iodine at the time of exposure, you can compete out the radioactive iodine. Also, while it's far more convenient to have your thyroid, you can survive without it as long as you supplement the hormones it produces, which are readily available and not that expensive. The thyroid is also easily accessible for removal should it become cancerous. I wouldn't expect mortality rates to be very high unless the cancer is undetected until it metastasizes.

*This has been a message from the biology sponsor; I now return you to your regularly scheduled engineering discussion.* :biggrin:

[1,1,2,3,5,8,13,21]

First of all, nuclear fission is very safe(if you are talking about an American reactor) Nuclear fission and fusion aren't very efficent, but they are a lot better than that coal crap. The problem is, uneducated hippies, who whine and (profane word) about finding a clean form of energy ignore nuclear because the news told them it is dangerous. Meanwhile, oil/coal barrons bribe scientists to slow production on nuclear/hydrogen fuel cell so they can make more money. (all the while i go off topic because i am in to politics) There is nuclear waste from uranium fission, but not hydrogen fusion, only helium. enentually, we will run out of hydrogen, but before we even eat up 1% of the world's hydrogen, a new energy source will be found (perhas matter/antimatter)

[faust9]

I love these discussion. I used to wear a TLD because I worked at a nuc plant. I decided to take a TLD on a flight just to see what kind of exposure I'd get--4 hour flight about 50mR. 1 month of doing primary samples--25mR. Flying was about twice as bad as standing in front of a sample sink. Flying was worse than any single month on the job. With the reactor shut down I still received about 5mR. I worked at an OEM manufacturer that used x-rays to verify foil runs on circuit boards. I got about 10-20mR every quarter there (again as read from a TLD). The added exposure from living close to a nuclear power plant is effectively zero. Even with minor accidents the exposure is still zero.

I will never again work in a plant(to much paperwork) but I don't fear them. They are not evil. US plants do not spew and belch radiation into the atmosphere. Heck, the worse US accident resulted in TMI resulted in a miniscule 1mR

"Health Effects

Detailed studies of the radiological consequences of the accident have been conducted by the NRC, the Environmental Protection Agency, the Department of Health, Education and Welfare (now Health and Human Services), the Department of Energy, and the State of Pennsylvania. Several independent studies have also been conducted. Estimates are that the average dose to about 2 million people in the area was only about 1 millirem. To put this into context, exposure from a full set of chest x-rays is about 6 millirem. Compared to the natural radioactive background dose of about 100-125 millirem per year for the area, the collective dose to the community from the accident was very small. The maximum dose to a person at the site boundary would have been less than 100 millirem.

In the months following the accident, although questions were raised about possible adverse effects from radiation on human, animal, and plant life in the TMI area, none could be directly correlated to the accident. Thousands of environmental samples of air, water, milk, vegetation, soil, and foodstuffs were collected by various groups monitoring the area. Very low levels of radionuclides could be attributed to releases from the accident. However, comprehensive investigations and assessments by several well-respected organizations have concluded that in spite of serious damage to the reactor, most of the radiation was contained and that the actual release had negligible effects on the physical health of individuals or the environment."

http://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-isle.html

We need more nuclear power plants. Build them breathe the fresh air. Love them.

[Morbius]

There is nuclear waste from uranium fission, but not hydrogen fusion, only helium.

1,2,3...

That's not quite correct. There is waste from nuclear fusion. The primary
reaction being considered is "D-T" fusion:

D + T --> He4 + n + 17.6 MeV

The byproducts of the reaction are Helium-4 which is not radioactive
and a 14.1 MeV neutron. However, that 14.1 MeV neutron is going to
make whatever it hits next radioactive, in all probability. Therefore,
you do have to dispose of the "first wall" as radioactive waste.


enentually, we will run out of hydrogen, but before we even eat up 1% of the world's hydrogen, a new energy source will be found (perhas matter/antimatter)

I wouldn't put much hope in matter/antimatter unless we find someplace
in space where we can mine anti-matter.

One can always make anti-matter - but where do you get the energy to
do that?

It's just like using hydrogen as a chemical fuel. We don't have much in
the way of a supply of hydrogen gas - only the hydrogen in water. But
water is hydrogen "ash" - it's hydrogen that has already been burned -
so there's no energy source there.

One can make hydrogen gas by electrolyzing water - but that takes
energy to do that - the same energy one gets when one burns the
resulting hydrogen. So if one already has the energy, one could just
use it instead of making hydrogen.

Making hydrogen only makes sense as an energy storage technique. One
could use nuclear power plants to cleanly make the energy to electrolyze
the hydrogen - which then could be burned in cars, airliners, and other
vehicles.

That would be a way to power our cars, airliners, etc on nuclear power
when they are too small to carry a reactor around.

Dr. Gregory Greenman
Physicist

[sid_galt]

I have a question about inertial fusion. I read an article on it on worldenergy.org which said that most of the kinetic energy of the d-t gas being compressed will be converted to internal energy leaving only the innermost part to fuse.

How will the kinetic energy be converted to internal energy. Could anyone elaborate?

Thank you

[hitssquad]

One could use nuclear power plants to cleanly make the energy to electrolyze the hydrogenWouldn't it make more sense to reduce water to hydrogen thermochemically?
http://www.greatchange.org/bb-thermochemical_hydrogen.html

--
Thermochemical decomposition of water results in hydrogen and oxygen through a process that allows an endothermic reaction to be induced at high temperatures and an exothermic reaction at low temperatures. The high temperature reactors, such as HTTR, are fitted as the source of high temperatures.
--