The Nuclear Power Thread

[Astronuc]

The NRC is waiting on utilities.

The ABWR and AP1000 are certified although there are some open issues.

 

[mheslep]

The NRC is waiting on utilities.

Eh? Waiting on them for what? The power companies submitted the applications for the 17 of these plants years ago.

 

[Astronuc]

Small Reactors Generate Big Hopes
http://online.wsj.com/article/SB10001424052748703444804575071402124482176.html

Three big utilities, Tennessee Valley Authority, First Energy Corp. and Oglethorpe Power Corp., on Wednesday signed an agreement with McDermott International Inc.'s Babcock & Wilcox subsidiary, committing to get the new reactor approved for commercial use in the U.S.

Although none have agreed to buy a reactor, the utilities' commitment should help build momentum behind the technology and hasten its adoption across the industry. It's a crucial first step toward getting the reactor design certified by the Nuclear Regulatory Commission. Early support from the three utilities, and four others that are mulling the agreement, increases the odds that customers will come forward in the future.
. . . .
"We see significant benefits from the new, modular technology," said Donald Moul, vice president of nuclear support for First Energy, an Ohio-based utility company.

He said First Energy, which operates four reactors at three sites in Ohio and Pennsylvania, has made no decision to build any new reactor and noted there's "a lot of heavy lifting to do to get this reactor certified" by the NRC for U.S. use.
. . . .

 

[mheslep]

Small Reactors Generate Big Hopes
http://online.wsj.com/article/SB10001424052748703444804575071402124482176.html

The small reactor idea makes so much sense on so many levels, perhaps the most promising is the reduction of regulatory problems.

• The B&W reactor would be built at the factory by one company, so the NRC can focus its attention there, and pay less attention to the construction process of every site contractor as there is at the large reactor projects.
• It is underground. I forget at the moment, but decades ago one of the icons of nuclear physics said commercial reactors should probably be buried. Finally. Burial should reduce the requirements of the containment structure, and ease public fears.
• On site, inside the containment structure storage of waste and new fuel reduces maintenance, and reduces much of the to/from transport of fuel/waste. Relieves the pressure of the waste issue until better approaches are found.
• Small size equals smaller cost, so no more bankrupt nuclear utilities leaving the public holding the bag.
• No water supply required.

I certainly hope it receives due attention.

 

[DnD Addict]

If one is to ignore all external costs associated with CO2 emissions, how well does nuclear power stand up aainst more convential power sources such as coal and natural gas? I am trying to understand why there is such an overlap between AGW skeptics an pro-nuclear power people.

What kind of mining practices are needed to mine thorium? I did a quik google search but didn't come up with anything.

 

[russ_watters]

If one is to ignore all external costs associated with CO2 emissions, how well does nuclear power stand up aainst more convential power sources such as coal and natural gas?

Not well at all. Coal and natural gas are vastly cheaper than just about anything else if you don't worry about controlling the pollution.

I am trying to understand why there is such an overlap between AGW skeptics an pro-nuclear power people.

I'm not sure what overlap you're seeing, but it may just be a biproduct of radical environmentalists being the most prominent opponents of nuclear power (that's basically by definition) and essentially all radical environmentalists are AGW proponents. For the rest of the population, I'd be surprised if there is much of a corellation.

[edit] Meh, the logic may be even more basic: AGW=bad for the environment, nuclear power is perceived as bad for the environment, therefore opponents of nuclear power will tend to be proponents of AGW theory.

 

[russ_watters]

The small reactor idea makes so much sense on so many levels, perhaps the most promising is the reduction of regulatory problems.

I certainly hope it receives due attention.

The political issues with nuclear power have to be worked out first and the political issues exist on a per-reactor basis, not on a per megawatt basis, so small reactors can only become a reality after a couple of decades of utility scale reactor resurgence.

 

[DnD Addict]

It is my understanding that current nuclear plants are only good for being a base load power plant*.

What % of natural gas power plants are used for base load power? Is it a significant %, or will nuclear power plants have to compete more against coal then natural gas?

*With the exception of BWR's. I have not been able to find anything about the economics of BWR's. How do they stack up to convential nuclear power plants?

 

[Astronuc]

It is my understanding that current nuclear plants are only good for being a base load power plant*.

What % of natural gas power plants are used for base load power? Is it a significant %, or will nuclear power plants have to compete more against coal then natural gas?

*With the exception of BWR's. I have not been able to find anything about the economics of BWR's. How do they stack up to convential nuclear power plants?

Gas plants are primarily peaking units. When the price of gas surged a few years ago, they actually became uneconomical to operate.

Most BWRs in the US have gone to 24 month cycles and are generally run as baseload, and many have been uprated on the order of 15-20% of the last two decades. Large capacity units are most economical as baseload - high capacity factor.

Nuclear plants compete primarily with coal. Natural gas plants generally are more competitive in terms of capital cost, and getting them online.

 

[DnD Addict]

If nuclear power plants cannot compete with coal if one ignores external costs for CO2,NOx,SOx,etc., does nuclear have side benefits that may make it desirable anyways?

For instance, I am told Generation IV plants will be able to be use High Temperature Electrolysis. How realistic is this plan? Will this let Nucear power plants be peaking plants (by shunting excess energy during the night into HTE) ?

 

[Astronuc]

If nuclear power plants cannot compete with coal if one ignores external costs for CO2,NOx,SOx,etc., does nuclear have side benefits that may make it desirable anyways?

Part of that is the fuel costs, and O&M. The new Gen 3+ plants, at least the AP1000, is supposed to have less piping and wiring, and a smaller footprint. On the other hand, cost of steel and concrete has driven up capital costs. The thing about coal is the ash-waste with its heavy metal content. In some cases, the material is just dumped rather disposed of as hazardous waste.

For instance, I am told Generation IV plants will be able to be use High Temperature Electrolysis. How realistic is this plan? Will this let Nucear power plants be peaking plants (by shunting excess energy during the night into HTE) ?

In some Gen-IV systems, they are looking at process heat/energy, e.g., for producing hydrogen. The higher the operating temperature, the more deleterious the environment is on materials. I certainly question the 'realism' behind Gen-IV.

 

[mheslep]

The political issues with nuclear power have to be worked out first and the political issues exist on a per-reactor basis, not on a per megawatt basis,

Agreed.

so small reactors can only become a reality after a couple of decades of utility scale reactor resurgence.

Perhaps, but doesn't necessarily follow. It may be that people will much more readily accept a small reactor that is buried out of sight, couldn't do as much damage even given some fantastic failure scheme, only has to have fuel or waste transport once every 60 years (if ever after startup), and doesn't need to be sited on some prime river or lake front property. Also since the small reactor construction time is so much faster (built off site) there's less time for mischief law suits and mauling in the agenda press.

 

[mheslep]

Not well at all. Coal and natural gas are vastly cheaper than just about anything else if you don't worry about controlling the pollution...

Well in the US at least. Overseas (Asia) nuclear has been much less expensive, highlighting the political cost attached nuclear in the US. Wind power in the wind belt is more or less competitive with natural gas.

 

[gmax137]

It is my understanding that current nuclear plants are only good for being a base load power plant*.

What % of natural gas power plants are used for base load power? Is it a significant %, or will nuclear power plants have to compete more against coal then natural gas?

*With the exception of BWR's. I have not been able to find anything about the economics of BWR's. How do they stack up to convential nuclear power plants?

The reason units (of any type) are operated as base load is because they are the cheapest to operate at that time. Nuclear units are perfectly capable of daily load following, but the Utility companies don't operate them that way - because at any time of day or night, they are the cheapest to run (once the company has made the significant investment required to build the unit). What makes the most sense at any given moment is the operating cost, not the capital cost, which has already been spent. The reason the nuclear units have a low operating cost is that the fuel is practically free. Compared to coal or gas, the uranium fuel is very inexpensive (and cheep to transport due to the limited amount of fuel required, relative to fossil fuels). There is a factor of approximately one million there, between the energy in a pound of uranium and the energy in a pound of coal. The only fuel cheaper than uranium is the wind - and it isn't really that much cheaper.

Gas fired plants aren't run for base load - for the same reason: They are the most expensive to operate, because their fuel is so pricey. So the Utility companies turn them on last and turn them off first (that's what it means to be a peaking unit.

BWR or PWR really doesn't matter in this context.

If nuclear power plants cannot compete with coal if one ignores external costs for CO2,NOx,SOx,etc.,

Where did you get that idea? Nuclear units produce 1/5 of our electricity in the US; in fact, nuclear units are the only competition that the coal plants have (and the coal plants have traditionally been given a free pass on their external costs).

 

[Astronuc]

Interesting picture showing Cerenkov radiation coming off a BWR assembly. The blue glow is roughly proportional to the local radiation intensity.

The BWR channel is about 5.86 inches face-to-face on the outside envelope.

 

[mheslep]

Interesting picture showing Cerenkov radiation coming off a BWR assembly. The blue glow is roughly proportional to the local radiation intensity.

The BWR channel is about 5.86 inches face-to-face on the outside envelope.

Pretty. Do you have a link to a larger photo? Googling doesn't turn up anything better.

 

[Astronuc]

Pretty. Do you have a link to a larger photo? Googling doesn't turn up anything better.

Unfortunately not. I took that off a presentation. I'll look to see if I can find a larger one.

 

[Astronuc]

Regulatory History Package on Design Certification
http://adamswebsearch2.nrc.gov/idmws/ViewDocByAccession.asp?AccessionNumber=ML003761550

 

[gmax137]

Regulatory History Package on Design Certification
http://adamswebsearch2.nrc.gov/idmws/ViewDocByAccession.asp?AccessionNumber=ML003761550

That's nice - how did you do that? It looks like a search on 'design certification' I didn't know there were 'saved' searches in ADAMS. Are there others like that (say, on other subjects)?

Thanks for the link !

 

[Astronuc]

That's nice - how did you do that? It looks like a search on 'design certification' I didn't know there were 'saved' searches in ADAMS. Are there others like that (say, on other subjects)?

Thanks for the link !

I was slogging through 10 CFR, NUREG 0800, and Reg. Guides, trying better to understand the DCD (and Tier 1 and 2) requirements. I came across, SECY-92-053, "Use of Design Acceptance Criteria During 10 CFR Part 52 Design Certification Reviews", and did a search on Google for that SECY. One of the links just happened to be that page I cited. Those documents are the whole basis behind the design certification and COL process and 10 CFR 52.

There may be other saved searches, but I'm not sure how to find a specific one. It was purely fortuitous and serendipitous to find the one I did.

 

[Astronuc]

Japan Steel Works takes a lead in large forgings.

Japan Steel Works (JSW) has completed its second press for ultra-large nuclear forgings, while Rolls-Royce and Larsen & Toubro will collaborate on instrumentation.

http://www.world-nuclear-news.org/NN_Links_for_the_supply_chain_0104101.html

WNA list of large forging shops.
http://www.world-nuclear.org/info/inf122_heavy_manufacturing_of_power_plants.html

 

[Astronuc]

Looking down into the reactor pressure vessel (RPV) of a PWR during a refueling. The core is about 10 m (33 ft) underwater, and the glow is the Cerenkov radiation.

Now imagine trying to do measurements and inspections at 10 m. Nowadays, rad-hardened digital cameras are used. Measurements are done in the spent fuel pool with the fuel also under about 10 m of water.

A ring of studs or bolts sorrounds the opening of the PV. The tall posts are alignment posts. The upper head has to precisely align within a few mils (~ 1 mm) in order for the control elements and control rod drives to be directly over their respective fuel assemblies.

 

[alcurad]

so I have a question, why is it that nuclear reactors always use steam turbines and nothing else? at least this is how it seems to me with my limited knowledge, isn't there any more efficient way to extract the heat and turn it into electricity?

 

[gmax137]

so I have a question, why is it that nuclear reactors always use steam turbines and nothing else? at least this is how it seems to me with my limited knowledge, isn't there any more efficient way to extract the heat and turn it into electricity?

Well, first, reactors don't 'always' use steam turbines - for example, the high temperature gas cooled pebble bed design uses the gas in essentially a brayton cycle device.

Second, steam turbine plants are not lacking in thermodynamic efficiency, the modern systems are pretty efficient. They are also used in coal fired units, where the fuel costs are high enough to drive efficiency gains.

Light water reactors use steam turbine plant for a number of reasons, but the main one (in my mind anyway) is because the electric power companies (who operate the reactors) are very familiar with the steam plant design since that's what they have in their coal fired units. There are differences, but they are minor. These steam plants are very robust and well understood, which means that they can operate continuously for long periods (months or years) - and this reliability is 'worth' as much or more than thermodynamic efficiency.

The cost to the power company of an 'inefficient' cycle is that they need to buy more uranium (since less efficient means less electricity for the same amount of fuel). But the fuel cost of running a reactor is a minor contributor to the total cost, so increasing efficiency of the cycle helps, but not by as much as you might think. And that's why reliability is really more important to the power company than thermodynamic efficiency.

Finally, the temperatures in the LWR design (reactor coolant at say 600 F in a PWR) are low by comparison to the gas temperatures in a coal fired unit or in a gas turbine, so you're not going to see anything other than a water-based Rankine cycle used. But then, that may be arguing in a circle (since the operating temperatures are selected to match the steam cycle).

 

[alcurad]

thanks, that explains a lot.

But the fuel cost of running a reactor is a minor contributor to the total cost, so increasing efficiency of the cycle helps, but not by as much as you might think. And that's why reliability is really more important to the power company than thermodynamic efficiency.

so, does that mean maintenance and operation costs trump fuel costs?

 

[QuantumPion]

thanks, that explains a lot.



so, does that mean maintenance and operation costs trump fuel costs?

yes, by a large margin (triple or quadruple).

 

[mheslep]

Nice post but I think it falls short in places:

Well, first, reactors don't 'always' use steam turbines - for example, the high temperature gas cooled pebble bed design uses the gas in essentially a brayton cycle device.

True, but all existing commercial reactors in the US at least use rankine steam for the primary cycle.

Second, steam turbine plants are not lacking in thermodynamic efficiency, the modern systems are pretty efficient. They are also used in coal fired units, where the fuel costs are high enough to drive efficiency gains.

Light water reactors use steam turbine plant for a number of reasons, but the main one (in my mind anyway) is because the electric power companies (who operate the reactors) are very familiar with the steam plant design since that's what they have in their coal fired units. There are differences, but they are minor. These steam plants are very robust and well understood, which means that they can operate continuously for long periods (months or years) - and this reliability is 'worth' as much or more than thermodynamic efficiency.

Obviously electric utilities are also very familiar and comfortable with natural gas fired Brayton cycle plants. There is an alternative reason than the comfort of the nuclear operators with Rankine steam, one I assert is far more likely to be dominate: government regulators (NRC in the US) are comfortable with the nuclear Rankine designs, and so only approve those designs.

The cost to the power company of an 'inefficient' cycle is that they need to buy more uranium (since less efficient means less electricity for the same amount of fuel). But the fuel cost of running a reactor is a minor contributor to the total cost, so increasing efficiency of the cycle helps, but not by as much as you might think. And that's why reliability is really more important to the power company than thermodynamic efficiency.

True, capacity factor ranks high, but it's misleading, I think, to say reliability trumps efficiency, end of story. Per a seminar run by the CEO of nuclear operator I once attended, the number one thing utilities want to do, or rather avoid, is they do not want to build more power plants, certainly not the expensive, capital intensive plants. They want to run the ones they have as near to maximum capacity as possible. Seen this way, reliability and efficiency are both important. If a utility were to choose a fleet of inefficient plants, they will simply have to build more of them to meet demand.

 

[mheslep]

yes, by a large margin (triple or quadruple).

Er, more specifically reactor down time trumps fuel costs by a large margin, since there's no $/kWh coming in when its down, and the utility may have to pay huge penalties for failure to provide promised supply in some states.

 

[Astronuc]

KAERI - Nuclear Power Reactor Technology
http://www.kntc.re.kr/openlec/nuc/NPRT/

Fuel Design and Fabrication
http://www.kntc.re.kr/openlec/nuc/NPRT/module2/module2_4/2_4.htm

Enjoy!

 

[gmax137]

Nice post but I think it falls short in places:
...
Obviously electric utilities are also very familiar and comfortable with natural gas fired Brayton cycle plants. There is an alternative reason than the comfort of the nuclear operators with Rankine steam, one I assert is far more likely to be dominate: government regulators (NRC in the US) are comfortable with the nuclear Rankine designs, and so only approve those designs.

Well, I'm not here to defend the NRC, but I do wonder, which designs have been proposed by any of the utility companies that were denied approval by the NRC? Actually, I'm not aware of any (and I would be interested to learn about any that were).

True, capacity factor ranks high, but it's misleading, I think, to say reliability trumps efficiency, end of story.

I said, efficiency isn't as important as you might think, not "reliability trumps efficiency, end of story."