|Feb6-05, 08:49 PM||#1|
hey need to write a paper on the advantages and disadvantages of nuclear fission.. this is briefly what i have come up with:
1) Nuclear Power: efficient and a good alternative to coal which is exhaustible..
1) It resulted in the development of atomic bombs which were dropped in hiroshima and nagasaki.
2) Nuclear reactors can spread radioactivity if proper precautions are not taken thus harming the environment to a certain extent.
are there any other aspects im missing?
|Feb6-05, 09:24 PM||#2|
|Feb6-05, 10:08 PM||#3|
well actually its the advantages and disadvantages of nuclear fission itself so i figured that i could mention atomic bombs as a disadvantage since it was possible to make due to the discovery of nuclear fission..
|Feb6-05, 10:34 PM||#4|
The advantage of fission is the high energy density relative to chemical-based energy, i.e. fossil fuel and the cost of production.
The disadvantages are the complex fuel cycle, the safety and security issues related to the nuclear fuel cycle and power plants, and the radioactive waste.
|Feb7-05, 06:03 AM||#5|
Less carbon dioxide emissions
With 100,000 year half-times, can you actually store it safetly anywhere on earth?
Questionable economics when taking account all factors (transport and storage of waste especially)
|Feb7-05, 07:08 AM||#6|
The point I was making is that the 2nd World War was arguably brought to an end by such weapons. Even with the terrible consequences a nuclear bomb entails, many of us owe our freedom to such events.
|Feb7-05, 08:07 AM||#7|
Plentiful supplies - the front end price goes up. If the demand were to double, the cost would increase, just as the cost of oil will increase with increase in demand or decrease in supply. Also, like oil, nuclear energy in the form of fissile materials like U235 is 'stored' - i.e. it is not unlimited. That is why the breeder reactors (convert U238 to fissile Pu239, and Th232 to U233) were considered. Th-232 is another abundant potential fuel supply, but one is still faced with the waste issue.
The long-half live isotopes are a small fraction. The more radioactive the isotope, the shorter the half-life. Most of the fission products will decay to 'inert' or 'non-radioactive' (stable) isotopes over days, weeks, years or decades, and in some cases centuries. The inert material will essentially entrap the radioactive material. On the other hand, it has been proposed to develop so-called actinide burners (reactors) to consume the long-lived transactinides. This is a controversial issue.
The economics of the entire fuel cycle is certainly subject to scrutiny as to its cost effectiveness. For instance, how much should the government subsidize the technology.
The economics are also different for the different situations. The US has had abundant fossil fuel supplies as well as uranium. France on the other hand has very limited fossil and uranium supplies.
|Feb7-05, 10:44 AM||#8|
Actually, nuclear power didn't result in the development of the atomic
bomb - more like the other way around!!!
The nuclear bomb project came to fruition in 1945. The first
commercial nuclear power plant was Shippingport in 1957. The first
reactor to generate electric power was Experimental Breeder Reactor I
[ EBR-I ] in 1951. Courtesy of Argonne National Laboratory - West:
The very first reactor was Fermi's "pile" at the University of Chicago;
December 1942. The first sizeable "production reactor" for producing
plutonium for the bomb was the Hanford "B Reactor" which began
operating in September 1944, if memory serves. Courtesy of the
U.S. Dept. of Energy:
The prototype for the Hanford production reactors was the X-10
reactor at Oak Ridge. Courtesy of USDOE:
The atomic bomb wasn't developed because we had nuclear power or
nuclear reactors. The bomb was the objective of the Manhattan Project.
In order to get plutonium for a bomb - Fermi developed the nuclear
reactor. But the atomic bomb was the objective from the start.
So nuclear reactors didn't beget atomic bombs - the quest for the atomic
bomb begat the nuclear reactor.
Another advantage of nuclear reactors over coal is that coal puts a
lot more radioactivity into the environment. Each year coal puts
about 2000 tons of uranium and 4000 tons of thorium into the
environment. Courtesy of the Oak Ridge National Laboratory:
Coal plants put radioactivity into the environment as part of their
normal operations. A nuclear plant would only put a significant amount
of radioactivity into the environment if there was some type of accident.
[Even the Three Mile Island accident - the worst in the USA - put a trivial
amount of radioactivity into the evironment.]
You have to look at the disadvantages in perspective. If an airliner
crashes - it can kill lots of people. But travel by airliner is much, much
safer than travel by automobile. The fact that there is the danger of
crashing means that airliners are designed and operated much more
safely than cars.
Because there is the potential of release of radioactivity to the
environment - the nuclear power plant is designed and operated in a
much safer manner than other forms of power generation.
Courtesy of the California Coastline project, here is a picture of the
Diablo Canyon Nuclear Power Plant:
See the two massive cylindrical domed buildings? Those are the
"containment buildings". The reactors are located in those buildings
which are designed to "bottle up" any accident.
The Three Mile Island Unit 2 which had the accident in 1979 has a
similar building that successfully "bottled up" the accident including
an explosion of hydrogen gas generated by oxidation of the zirconium
cladding. Courtesy of NukeWorker.com, note the cylindrical buildings,
which house the reactors. Unit 2 is the closer of the two, next to the
green turbine hall:
The only radioactivity that was released to the environment was done
on purpose - so that the radiation dose to workers entering a certain
area of the plant would be less than if that radioactivity were not
vented. The amount vented was much much less than the natural
radioactivity normally found in the environment.
Do you know of any other industry that provides such at "last ditch"
safety system. Your airliner doesn't have a great big parachute to lower
you gently to Earth should everything go wrong.
Dr. Gregory Greenman
|Feb7-05, 12:26 PM||#9|
What isotope has a 100,000 year half-life that you are refering to ?
The longest lived fission product [ the true "waste" ] of any consequence
is Cesium-137 and that has a half-life of just 30 years.
Even Plutonium-239, one of the longest lived actinides has a half-life of
24,000 years. However, Pu-239 and the other actinides can be recycled
back to the reactor to be burned as fuel.
Therefore, with the reprocessing and recycling of nuclear waste - the
longest lived half-life of concern is Cesium-137 with a half-life of 30 yrs.
Actually, the economics of transport and storage of nuclear waste is
already in the cost of nuclear electricity. The U.S. Government levies
a special tax on the utilities that use nuclear power plants to pay for
the disposal facility that will be provided by the Government.
[This is not unlike the "landing fees" that the FAA charges airlines for
every landing - which pays for the air traffic control system which is
operated by the Government. That way - an independent, non-profit
oriented agency provides the critical service - traffic control or waste
disposal - and the industry foots the bill. ] At present, the US Government
has collected about $17 Billion, at my last reckoning, for building and
operating the disposal facility.
The U.S. Government also requires that the utility put money in an
escrow account to pay for decomissioning costs. Nuclear power plants
like Shippingport, Elk River, and Trojan have been completely dismantled
well within the costs provided by the escrow funds. Courtesy of the
Oregon Dept. of Energy:
So there are no hidden costs in nuclear-generated electricity. It is all
being paid up-front.
Dr. Gregory Greenman
|Feb7-05, 01:11 PM||#10|
thanks much for your posts guys.. appreciate it
|Feb7-05, 02:24 PM||#11|
If you are talking about the process - "nuclear fission" - and not the
applications; then there are no advantages / disadvantages - it just
It's like talking about the advantages and disadvantages of gravity.
Dr. Gregory Greenman
|Feb7-05, 02:45 PM||#12|
i see what u mean... my bad..
|Feb10-05, 04:57 PM||#13|
for my paper, would i be correct if i said that nuclear fission was discovered by Otto Hahn and Strassman ( sp?) ?
My paper is due tomorrow and i have written about Otto Hahn as the discoverer along with strassman although a look at a book on physics says that Lisa Mietner discovered it along with Otto Freich.. not sure if i should redo my paper ( since a major chunk is about the discoverer who in my paper, is otto hahn as opposed to mietner )
|Feb11-05, 09:24 AM||#14|
Otto Hahn and Fritz Strassman did the experiment that demonstrated
fission for the first time - but they did not understand what they had
discovered. They noted that when you bombard a nuclide with neutrons,
you frequently get a daughter product that is one higher in atomic
number. [ That's because the nuclide is made radioactive and decays
by beta-minus decay which increases the atomic number by 1 ].
So Hahn and Strassman tried neutron bombardment of the naturally
occuring element with the highest atomic number - uranium. At first,
they got a null result, because one of the elements used in the chemical
extraction - was also a fission product - so its presence was not
considered anomalous. A later extraction technique used different
elements - and showed that daughters of lesser atomic number - not
greater atomic number were created.
It was Lise Meitner [ with the aid of Otto Frisch ], that, upon learning
about the Hahn-Strassman experiment; correctly interpreted the results
as a demonstration of fission. Meitner was going to tell Hahn and
Strassman of her conclusion; however Meitner was of Jewish decent -
and the Nazis were after her. She escaped to the USA before telling Hahn
and Strassman of her conclusion. Later, Hahn and Strassman correctly
interpreted their result.
So Hahn and Strassman did the experiment. Meitner was the first to
explain it. Hahn and Strassman reached the same conclusion as Meitner
independently - but later.
In my book; I'd credit Lise Meitner as the one that discovered fission.
Dr. Gregory Greenman
|Feb11-05, 09:38 AM||#15|
Otto Hahn received The Nobel Prize in Chemistry 1944 "for his discovery of the fission of heavy nuclei". It would be more appropriate in Physics.
Personally, I think Lise Meitner should have been a co-recipient.
One of my goals as a nuclear engineer is to see that Meitner and other women scientist/engineers get the recognition they deserve!
|Feb11-05, 10:23 AM||#16|
Yes - we were discussing this at the lunch table at the Lab recently.
One of our retirees is a science history buff and was asking questions
about Nobel Prize recipients. [ Who was the youngest in Physics, how
many women got the Nobel Prize in Physics....]
We agreed that Lise Meitner should have received the Nobel Prize for
her interpretation of the Hahn-Strassman experiment. I believe this has
been a point of contention between the scientific community and the
Swedish Academy. Because Lise Meitner was slighted by the Swedish
Academy - the U.S. Government awarded her the Fermi Award in
recognition of accomplishment.
Courtesy of the University of California - San Diego Supercomputer
"But the separation of the former collaborators and Lise's scientific and
actual exile led to the Nobel committee's failure to understand her part
in the work. Later Hahn rationalized her exclusion and others buried her
role ever deeper. The Nobel "mistake," never acknowledged, was partly
rectified in 1966, when Hahn, Meitner, and Strassmann were awarded the
U.S. Fermi Prize."
You can read more in the following Lise Meitner biography:
Courtesy of NobelPrize.org:
In attempts to make transuranium elements, i.e., elements with a higher
atomic number than 92 (uranium), by radiating uranium atoms with
neutrons, Hahn discovered that one of the products was barium, a lighter
element. Lise Meitner, at the time a refugee from Nazism in Sweden, who
had earlier worked with Hahn and taken the initiative for the uranium
bombardment experiments, provided the explanation, namely, that the
uranium atom was cleaved and that barium was one of the products .
Hahn was awarded the Nobel Prize for Chemistry in 1944 "for his
discovery of the fission of heavy nuclei", and it can be wondered why
Meitner was not included. Hahn's original intention with his experiments
was later achieved by Edwin M. McMillan and Glenn T. Seaborg of
Berkeley, who were given the Nobel Prize for Chemistry in 1951 for
"discoveries in the chemistry of transuranium elements".
Dr. Gregory Greenman
|Feb11-05, 10:38 AM||#17|
Through a very dear friend of mine, a woman scientist at the Lab that I
first met years ago when we attended the same Univerisity as undergrads;
I became aware of an organization of women scientists that are
attempting to rectify the dearth of women in science:
The Math/Science Network sponsors workshops called "Expanding Your
Horizons". They showcase the careers of women scientists to serve as
role models for young junior and senior high school women.
Our local EYH conference in the Tri-Valley area of San Francisco's
East Bay is held in February / March. The conference is co-chaired by
a woman scientist from Lawrence Livermore and a woman scientist
from Sandia National Laboratory - Livermore with financial assist
from LLNL, SNL-L, and many local companies that employ scientists.
A very worthwhile organization and mission.
Dr. Gregory Greenman
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