The Nuclear Power Thread

[zapperzero]

Actual capacity factors are much lower - more on the order of 25.
http://en.wikipedia.org/wiki/Capacity_factor.

The source you cite does not really support your assertion. Perhaps you can find another one.

 

[mheslep]

I was being charitable.

Regarding "Nuclear is just a bit more expensive than wind"? My point was that nuclear might be considerably more expensive than wind for the moment.

 

[zapperzero]

Regarding "Nuclear is just a bit more expensive than wind"? My point was that nuclear might be considerably more expensive than wind for the moment.

Yes, this is my impression as well. I do not see a rush of investors into nuclear. Perhaps it is perceived as high-risk, post-Fukushima? What usually happens with high-risk ventures is the cost of financing increases.

I am baffled by the evolution of the price of uranium, though, long-term (or what constitutes long term for markets, in any case - the past 15 years). Seems there was a bubble in '05-'07, then a slow meltdown (pun intended).

 

[wizwom]

Wind is much smaller scale; you can reasonable do one 10 KW rated wind turbine and expect they same payback and profitability as a farm of 100 MW.
Nuclear, because you need licensing and staffing, is decidedly NOT entirely scalable.
Since these costs are fairly constant, there is no reason to go small.

But total lifecycle cost for nuclear is around 6 cents a KWh; for wind it is more like 17.

 

[zapperzero]

But total lifecycle cost for nuclear is around 6 cents a KWh; for wind it is more like 17.

Maybe you can source this statement?

 

[MadderDoc]

Wind is much smaller scale; you can reasonable do one 10 KW rated wind turbine and expect they same payback and profitability as a farm of 100 MW.
Nuclear, because you need licensing and staffing, is decidedly NOT entirely scalable.
Since these costs are fairly constant, there is no reason to go small.

But total lifecycle cost for nuclear is around 6 cents a KWh; for wind it is more like 17.

That is not realistic, the small wind turbine will certainly cost more per kWh produced, just like a 200 MW farm will produce more cheaply than a 100 MW farm. Last time I looked, 1 million Euro would buy about 1 MW capacity (looking for a current commercial wind turbine in the ~2 MW size) Typically such a machine would be designed/sited to maximize energy yield per Euro invested at a capacity factor of about 0.25-0.40, so that over an expected life time of 20 years it would produce 45-70 million kWh per installed MW. Even assuming the project price would mount to as much as double the price of the wind turbine, that would still be only about 3-4 cents a kWh. To be sure there are different estimates out there, but I don't know how you get it to be 17 cents a kWh, it doesn't look like anything I've seen elsewhere.

 

[wizwom]

A quick survey shows a 100kW turbine at $35,000 & a 10kW at $7,000; s expected, prices are all over. The IEA report from 2011 http://www.nrel.gov/docs/fy12osti/53510.pdf puts the total cost at $1500-$2000 per installed rated kW
Capacity factors are in the 25-30% range; the 40% was never seen anywhere, even 35% was anomalous. This means that the cost per usable kW is now $5000-$7400.

That report shows the cost dropped to near 5 cents in 2007, but then has risen to 7c.
Sorry for the old data.

 

[hill hermit]

snip
There may be a thread around here somewhere about it, but a few years ago, I did some calculations about solar and concluded that with good solar panels, we'd nee to cover an area of about 300 miles square - similar to your father's calculation of the entire state of Arizona.
snip

Sorry that my first post will be "off track" where this thread is currently but I simply had to register to point out this unbelievably huge mistake.

FYI- the state of Arizona covers 114,006 square miles. Much, much larger than the 300 square miles needed to power the entire US by your own calculations. Phoenix AZ covers roughly 500 square miles, so in exchange for giving up less land than a single large metro area we could power the US with a truly clean energy.

-hh

 

[mheslep]

A quick survey shows a 100kW turbine at $35,000 & a 10kW at $7,000; s expected, prices are all over.

What survey? Yours? This IEA report:

The IEA report from 2011 http://www.nrel.gov/docs/fy12osti/53510.pdf puts the total cost at $1500-$2000 per installed rated kW

is for the *installed*, up and running cost for utility scale (>1MW) turbines. What source reports an installed cost for a 100kW turbine?

 

[russ_watters]

Sorry that my first post will be "off track" where this thread is currently but I simply had to register to point out this unbelievably huge mistake.

FYI- the state of Arizona covers 114,006 square miles. Much, much larger than the 300 square miles needed to power the entire US by your own calculations. Phoenix AZ covers roughly 500 square miles, so in exchange for giving up less land than a single large metro area we could power the US with a truly clean energy.

-hh

Welcome to PF!

I didn't say "300 square miles", I said "300 miles square". As in - a square 300 miles on a side or 90,000 square miles. The reason I worded it that way is that most people can wrap their arms around the size better if you describe the dimensions, not the area.

 

[MadderDoc]

<..>
Capacity factors are in the 25-30% range; the 40% was never seen anywhere, even 35% was anomalous. <..>.

IIRC, the world record for a single commercial wind turbine is a capacity factor of 44 % over a (so far) 9 year operation time. Danish offshore wind farms operate overall well above 35 %. Horns Rev II (a 209 MW farm) has performed best, with a capacity factor of about 47 %. The second best measured by capacity factor is Rødsand II (207 MW), at 42 %.

 

[Astronuc]

Scotland and Denmark seem to be in really good spots for wind energy. Many coastal areas are.

US
http://rredc.nrel.gov/wind/pubs/atlas/
http://rredc.nrel.gov/wind/pubs/atlas/maps/chap2/2-06m.html

http://www.windpoweringamerica.gov/wind_installed_capacity.asp?&print
Canada
http://www.windatlas.ca/en/maps.php

Europe
http://www.windatlas.dk/europe/index.htm
http://www.windatlas.dk/europe/landmap.html

World
http://www.windatlas.dk/World/Index.htm
http://www.windatlas.dk/World/Atlases.html

This is not exactly nuclear power though.

 

[MadderDoc]

Scotland and Denmark seem to be in really good spots for wind energy. Many coastal areas are.<..>
This is not exactly nuclear power though.

No that's true, nuclear power tends to become irrelevant such places, unless nuclear load-following power can be produced economically. I don't know if new types of nuclear promise that. As soon as wind power is being viably produced in a region, the need will be for viable absorbers of the variability that is then inherently produced too, rather than for what nuclear traditionally has to offer.

 

[Astronuc]

No that's true, nuclear power tends to become irrelevant such places, unless nuclear load-following power can be produced economically. I don't know if new types of nuclear promise that. As soon as wind power is being viably produced in a region, the need will be for viable absorbers of the variability that is then inherently produced too, rather than for what nuclear traditionally has to offer.

Nuclear energy is generally produced in base load, but the French do a lot of load following and frequency control with their nuclear units.

With wind at 50% availability one would twice the installed capacity on a kW basis to achieve the same kWh as compared to a unit that runs constantly at full power. Many nuclear units achieve 90+% capacity factor. Of course, there are some units that have poor performance.

If wind is only available at 35% or 20%, then the number of wind units greatly increases, as does the transmission infrastructure. If one looks at the various atlases, there are some areas that have great wind capability, but many larger areas that do not. In the US, the majority of population live in areas of relatively low wind availability.

 

[mheslep]

...In the US, the majority of population live in areas of relatively low wind availability.

That's true if US offshore wind potential is omitted. At the moment offshore wind is not economic nor technically practical on the US east coast due to hurricanes, but that may change w/ stronger wind tower designs.

 

[MadderDoc]

Nuclear energy is generally produced in base load, but the French do a lot of load following and frequency control with their nuclear units.

OK, yes, With the very high penetration of nuclear power in France there would be little other choice than to sacrifice on the capacity factor, such as to make the production fit the variable consumption, or alternatively export periodically against little demand from other countries. Perhaps France seen in isolation can be said to be oversupplied with nuclear power. By the same token, France might not be in a good position to start exploiting its available wind resources. (Newly added wind power would act in the system as additional consumption variation, only then from 'negative consumers')

With wind at 50% availability one would twice the installed capacity on a kW basis to achieve the same kWh as compared to a unit that runs constantly at full power. Many nuclear units achieve 90+% capacity factor. Of course, there are some units that have poor performance.

I am not sure what you mean by availability of wind in this context, but you do seem to indicate it to be a measure comparable to the capacity factor of nuclear. The best wind sites over here may well have wind turbines operating at capacity factor about 50%, and in a mathematical sense that means that a same sized wind turbine or another system running at 100 % could replace two of such units. Or, could one say, one of the 50% capacity factor turbines replaces two turbines running at a capacity factor of 25 %. However, I am not sure what the superposition elucidates. Whether you look at a nuclear plant targeting a 90% capacity factor, or a wind turbine at a given site targeting a 50% capacity factor, in either case that target is an effect of economic optimisation.

If wind is only available at 35% or 20%, then the number of wind units greatly increases, as does the transmission infrastructure. If one looks at the various atlases, there are some areas that have great wind capability, but many larger areas that do not. In the US, the majority of population live in areas of relatively low wind availability.

Well, of course you can have too small and/or too distant wind resources left worth exploiting, and maybe that is the case in USA. Certainly the magnitude and quality of the wind resource at a given site strongly influence the economical viability of a wind power project, and the incorporation of such a project in the existing grid must of course make economic sense. However, I can see no problem with wind turbines operating at capacity factors of 35% or 20% if that now happens to be the economic optimum for the sites. About 30 GW of on average less capacity factor is operating onshore in Germany currently, I never thought that to be a problem. While the push has become for adding offshore wind power from the North Sea there will indeed be a need for another investment in the transmission infrastructure, but so what, I can't remember when there wasn't :-)

 

[zapperzero]

WASHINGTON, Aug. 7, 2012 /PRNewswire-USNewswire/ - The U.S. Nuclear Regulatory Commission (NRC) acted today to put a hold on at least 19 final reactor licensing decisions – nine construction & operating licenses (COLS), eight license renewals, one operating license, and one early site permit – in response to the landmark Waste Confidence Rule decision of June 8th by the U.S. Court of Appeals for the D.C. Circuit.

The NRC action was sought in a June 18, 2012 petition filed by 24 groups urging the NRC to respond to the court ruling by freezing final licensing decisions until it has completed a rulemaking action on the environmental impacts of highly radioactive nuclear waste in the form of spent, or 'used', reactor fuel storage and disposal.

 

[Astronuc]

First license for Canadian new build
http://www.world-nuclear-news.org/NN-First_licence_for_Canadian_new_build-2008127.html

The nuclear site preparation [Darlington] license issued to Onatrio Power Generation (OPG) will be valid for ten years, from 17 August 2012 to 17 August 2022.


Meanwhile, back in Washington DC - NRC suspends final licensing decisions
08 August 2012

Licences for US nuclear plants - including those for new construction and life extension - will not be issued until the Nuclear Regulatory Commission (NRC) addresses a court decision on waste confidence. However, licensing activities will continue as normal.

On 8 June, the US Court of Appeals for the District of Columbia found that the NRC's rules for the temporary storage and permanent disposal of nuclear waste stood in violation of the National Environmental Policy Act. This requires that either an environmental assessment or environmental impact statement be prepared for all major government agency actions.
. . . .

Regarding the development of a waste facility, the court noted that 20 years of work towards building a repository was effectively abandoned when the Department of Energy withdrew its application for the Yucca Mountain repository in 2010, and that, "At this time there is not even a prospective site for a repository, let alone progress towards the actual construction of one."

. . . .

and how many $billion wasted?

 

[Astronuc]

Opportunities at Culham Centre for Fusion Energy in UK.

http://www.culhamphd.org.uk/
http://www.culhamphd.org.uk/typicalPhDtopics.html

http://www.york.ac.uk/physics/postgraduate/fusion-dtn/

Also - Science and Technology Facilities Council
http://www.stfc.ac.uk/Our%20Research/14397.aspx

 

[Astronuc]

http://www.world-nuclear-news.org/C_Coping_with_energy_transition_1411121.html

14 November 2012

EOn continues to struggle under German energy policy, with gas generation made "barely profitable" by pro-renewable market arrangements and nuclear generation slashed and taxed by government decree.

The utility has summarised its performance from January to the end of September, explaining to shareholders that it would honour dividend predictions for 2012, but would revise ambitions for 2013 and 2015. Despite a worsening outlook, the company still recorded pre-tax earnings of €8.8 billion ($11.2 billion) with 'underlying net income' of about €4 billion ($5.0 billion) for the first nine months of 2012.

One problem is that renewable generation is given priority access to the grid when it is available. This sometimes prevents gas-fired generation from operating during peak hours and has altered the economics of gas to such an extent that it is now "barely profitable to operate," said CEO Johannes Teyssen. "In most European markets, the gross margin for gas-fired units is approaching zero or is indeed already negative."

. . . .

This an example of a poor energy and economic policy on the part of the German government, and it is harming the economy.

 

[etudiant]

German energy policy is constrained by anti nuclear sentiment on the one hand (fuelled by media support of a small cadre of activists plus public distrust sustained by unrelenting publicity focused on the nuclear industry's failures) along with the recognition that gas supply from Russia is unreliable (it was turned off just a couple of winters ago).
The fix is more coal fired power, because the 'green' alternatives are falling well short of requirements for reliability and quantity.

 

[Astronuc]

mPower empowered by SMR funds
http://www.world-nuclear-news.org/NN-mPower_empowered_by_SMR_funds_121112a.html

Meanwhile

Alstom unveils world's longest turbine blade (for large low pressure (LP) steam turbines)
http://www.world-nuclear-news.org/C-Alstom_unveils_longest_turbine_blade-2011128.html

Also, note that Europe uses 50 Hz, to large turbines are usually 1500 RPM (although some are designed for 3000 rpm) rather than 1800 rpm used in 60 Hz systems.

In 3000 rpm turbines, the last stage blade length is on the order of 1.35 m
http://www.rwe.com/web/cms/mediablob/en/247554/data/235582/1/rwe-power-ag/nuclear-power/blob.pdf

 

[CFDFEAGURU]

I have done work on the ALSTOM HP and LP coolers used in the GT-24 and GT-26 gas turbines. Lots of ASME code calcs ...

 

[Astronuc]

Bethlehem-based Lehigh Heavy Forge Corp. teaming with N.C. company to make nuclear reactors
http://www.lehighvalleylive.com/bethlehem/index.ssf/2012/11/lehigh_valley_forge_teaming_wi.html

Bethlehem-based Lehigh Heavy Forge Corp. expects to add 100 jobs over the next 10 years through a partnership announced today with a North Carolina nuclear technology company.

The South Side foundry is teaming with the Babcock & Wilcox Co. to supply forgings for a new brand of small modular reactors being developed by B&W. Officials announced the partnership at an event joined by Pennsylvania Gov. Tom Corbett and local business and government officials.

. . . .

 

[Astronuc]

On 2 December 1942 a team of 49 scientists led by Enrico Fermi started the world's first nuclear reactor. 70 years on two of team recounted their experiences in this video.

Argonne nuclear pioneers: Chicago Pile 1

 

[Astronuc]

Some background on Nuclear Reactor Materials and Fuels.

http://cryptocomb.org/Nuclear Reactor Materials and Fuels.pdf

It's mostly correct, but a bit off in places.

Also, for material properties - http://www.nrc.gov/reading-rm/doc-collections/nuregs/contract/cr7024/cr7024.pdf

 

[Astronuc]

Prometheus Project Reactor Module Final Report, for Naval Reactors Information
http://www.osti.gov/energycitations/servlets/purl/884680-LsvaFN/884680.pdf (64 MB)

1771 References in Bibliography

It's reasonably comprehensive on the state of the art, and relevant to many topics in the forum. It's a good supplement to the Gen-IV literature.

 

[Astronuc]

New US Nuclear Builds

Vogtle 3 and 4 and V C Summer 2 and 3 (both twin AP1000 sites) are under construction.

Vogtle has been doing ground work for sometime.

On March 9, pouring of the basemat for Unit 2 commenced. It lasted about 50 hours as a continuous pour.

The basemat provides a foundation for the containment and auxilary buildings that are within the unit's nuclear island. Measuring 1.8 metres thick, the basemat required some 5350 cubic metres of concrete to cover an area about 76 metres by 49 metres. The concrete-pouring process took just over 50 hours and was completed at about 10.00am on 11 March.

http://www.world-nuclear-news.org/NN-AP1000_construction_underway_at_Summer-1203134.html


Update: March 13, 2013

Southern Nuclear began pouring the basemat at Vogtle 3, a day after SCANA/SCE&G began the pour at Summer 2. It takes about 50 hours to pour the basemat.

http://chronicle.augusta.com/news/metro/2013-03-13/concrete-poured-new-vogtle-reactor-foundation

Southern Nuclear has begun pouring of specially designed basemat concrete for the foundation of its Unit 3 Plant Vogtle reactor, just three days after similar steps were completed at SCANA’s V.C. Summer plant in South Carolina.

http://chronicle.augusta.com/news/m...eaviest-reactor-parts-moved-plant-vogtle-site

(Jan 24) The reactor vessel head, weighing 160 tons, serves as the “lid” of the Unit 3 reactor and will be bolted to the even-larger reactor vessel body – a 300-ton component that remains in Savannah, Ga., awaiting shipment to the site aboard a specially built rail car.

 

[Astronuc]

Japan signs deal with Turkey to build nuclear plant
http://www.cnn.com/2013/05/04/world/europe/turkey-japan-nuclear/?iref=obinsite

(CNN) -- Turkey and Japan have agreed to a $22 billion deal to build a nuclear power plant in Turkey, the semi-official Turkish news agency Anadolu reported.
. . . .

http://www.atmea-sas.com/scripts/ATMEA/publigen/content/templates/Show.asp?P=57&L=EN

Large LWRs of Gen 3 generation are on the order of 1.1 to 1.2 GWe. ATMEA is roughly the same capacity as Westinghouse's AP-1000.

 

[Astronuc]

Iaea inpro

The International Project on Innovative Nuclear Reactors and Fuel Cycles (INPRO) was established in 2000 to help ensure that nuclear energy is available to contribute to meeting the energy needs of the 21st century in a sustainable manner. It is a mechanism for INPRO Members to collaborate on topics of joint interest. The results of INPRO's activities are being made available to all IAEA Member States.

http://www.iaea.org/inpro/
http://www.iaea.org/INPRO/about.html

INPRO Programme 2012-2013
Project 1: National Long Range Nuclear Energy Strategies
Project 2: Global Nuclear Energy Scenarios on Sustainable Nuclear Energy
Project 3: Innovations in Nuclear Technology

 

[Astronuc]

A relatively new development in aneutronic p+B11 fusion.

. . . .
A team led by Christine Labaune, research director of the CNRS Laboratory for the Use of Intense Lasers at the Ecole Polytechnique in Palaiseau, France, used a two-laser system to fuse protons and boron-11 nuclei. One laser created a short-lived plasma, or highly ionized gas of boron nuclei, by heating boron atoms; the other laser generated a beam of protons that smashed into the boron nuclei, releasing slow-moving helium particles but no neutrons. The researchers describe their work in Nature Communications today.
. . . .
Timing was crucial for the success of the experiment, says study co-author Johann Rafelski, a theoretical physicist at the University of Arizona in Tucson. The boron plasma generated by the laser lasts only about one-billionth of a second, and so the pulse of protons, which lasts one-trillionth of a second, must be precisely synchronized to slam into the boron target. The proton beam is preceded by a beam of electrons, generated by the same laser, that pushes away electrons in the boron plasma, allowing the protons more of a chance to collide with the boron nuclei and initiate fusion.

. . .

http://www.nature.com/news/two-laser-boron-fusion-lights-the-way-to-radiation-free-energy-1.13914

http://www.nature.com/ncomms/2013/131008/ncomms3506/full/ncomms3506.html

 

[jimgraber]

Congratulations to the team for their successful demonstration. Are there any energy in/energy out calculations for the experiment? And a fortiriori, for a scaled up actual power producing reactor?

 

[mheslep]

From the abstract alone I'm not clear what contribution is made by this work at CNRS on fusion. Fusion with p+B11 has been done long ago with accelerators and targets, and beam fusion of any kind has no path to net power. Is the contribution purportedly in the use of lasers?

 

[Astronuc]

"First concrete had been poured at the construction site for the world’s first small modular reactor (SMR) project. The SMR under construction is called the CAREM 25, which is not only an indigenous Argentinian design, but also the first-ever indigenous Argentinian power reactor design."

http://ansnuclearcafe.org/2014/02/13/carem-25-carries-torch-for-smr-construction/

 

[Jon Richfield]

If everyone here will pardon my ignorance as a non-physicist, could someone please tell me why it is necessary for the B11 to be in plasma form? The protons certainly, but is there some subtle resonance that bulk boron lacks that is necessary for the nuclear fusion and subsequent fission? It is not as if the resultant He4 would form any persistent ash or poison, surely?

 

[Astronuc]

If everyone here will pardon my ignorance as a non-physicist, could someone please tell me why it is necessary for the B11 to be in plasma form? The protons certainly, but is there some subtle resonance that bulk boron lacks that is necessary for the nuclear fusion and subsequent fission? It is not as if the resultant He4 would form any persistent ash or poison, surely?

It's a consequence of the process and the temperature.

 

[Astronuc]

The Czech utility CEZ has canceled plans for 2 additional nuclear units at Temelin. The economics have changed.

http://www.world-nuclear-news.org/NN-CEZ-cancels-Temelin-expansion-tender-1004144.html

One of the designs was an advanced VVER (MIR-1200 or AES-2006; ~1200 MWe gross, ~1115 MWe net), which was competing against the AREVA EPR (1600 MWe) and Toshiba/Westinghouse AP1000 (1150 MWe).

http://www.world-nuclear-news.org/C-Vendors-react-to-Czech-cancellation-2204141.html

http://www.iaea.org/INPRO/7th_Dialogue_Forum/Rosatom_1.pdf

http://www.mir1200.cz/en/design-solution/references/index.shtml
http://www.mir1200.cz/en/design-solution/main-components/reactor/index.shtml

http://www.cez.cz/en/power-plants-a...e-temelin-nuclear-power-plant/technology.html

 

[Jon Richfield]

Hmmm... "The economics have changed" huh? Watch this space. Short term there is some sort of kerfuffle building up to the South East on the fringes of a lagoon off the Med that affects gas markets; there is a general fuss about carbon burning coinciding with all sorts of shutting down of nukes, there is a huge political AND technical wrangle about fracking and a lot of credibility gap about renewables...
Any bets about how often and in which directions the economics change again?
I know about the long-term directions for us to get serious (adequate) amounts of power, but there will always be politics and "economics" in the way.

 

[Astronuc]

Some information on the evolution of BWR reactors and the ABWR.

http://www.hitachi-hgne-uk-abwr.co.uk/downloads/UKABWR-GA91-9901-0034-00001-REVA_C2a_Public.pdf

 

[Astronuc]

When the first edition of Section III of the ASME Boiler and Pressure Vessel Code appeared 50 years ago, it provided rules for three classes of pressure vessels for nuclear power plants.

This was, however, the birth of an industry, an entire supply chain that would eventually provide one-fifth of the electricity consumed annually by the United States. So it quickly became apparent that the industry needed to address many issues besides the design and construction of the reactor vessels. More guidance was needed—and welcomed—by the industry and other stakeholders.

Section III eventually grew to encompass rules governing the construction and inspection during the building of storage tanks, piping, pumps, valves, containments, and other components of nuclear power plants. The code also addresses containment systems for storage and transport packaging of spent fuel and high-level radioactive material and waste.

Read more - https://www.asme.org/engineering-topics/articles/nuclear/a-group-effort-that-grew

Topics on Nuclear Energy
https://www.asme.org/engineering-topics/nuclear-power

 

[Astronuc]

A perspective on materials and advanced nuclear systems.

http://www.lanl.gov/conferences/marie/decadal/docs_open/Decadal-Plenary_Talk-Maloy1.pdf

 

[Astronuc]

Thorium

Safety and Regulatory Issues of the Thorium Fuel Cycle

http://pbadupws.nrc.gov/docs/ML1405/ML14050A083.pdf

Note the authors are from ORNL.

Thorium has been widely considered an alternative to uranium fuel because of its relatively large natural abundance and its ability to breed fissile fuel (²³³U) from natural thorium (²³²Th). Possible scenarios for using thorium in the nuclear fuel cycle include use in different nuclear reactor types (light water, high temperature gas cooled, fast spectrum sodium, molten salt, etc.), advanced accelerator-driven systems, or even fission-fusion hybrid systems. The most likely near-term application of thorium in the United States is in currently operating light water reactors (LWRs). This use is primarily based on concepts that mix thorium with uranium (UO₂ + ThO₂), add fertile thorium (ThO₂) fuel pins to LWR fuel assemblies, or use mixed plutonium and thorium (PuO₂ + ThO₂) fuel assemblies.

And FYI - Regulation of Radioactive Materials
http://www.nrc.gov/about-nrc/radiation/protects-you/reg-matls.html

 

[mheslep]

I'm curious how the breeding chain in a solid fuel Th based breeder works. That is, I understood that once the Th232 breeds into Pa233, the Pa then had to be continually removed from the core while it decayed in days to U233, else a high fraction was likely to undergo neutron capture. Continual removal of Pa233 is a resolvable chemical and plumbing problem in a molten reactor, but I don't follow how it is possible in a solid fueled LWR.

 

[Astronuc]

I'm curious how the breeding chain in a solid fuel Th based breeder works. That is, I understood that once the Th232 breeds into Pa233, the Pa then had to be continually removed from the core while it decayed in days to U233, else a high fraction was likely to undergo neutron capture. Continual removal of Pa233 is a resolvable chemical and plumbing problem in a molten reactor, but I don't follow how it is possible in a solid fueled LWR.

I'll try to find some information on Th-U233 programs.

Meanwhile - the Lightbridge patents on a Th-inspired novel fuel design for LWR and CANDU fuel.

http://www.google.com/patents/US20110255651
http://www.google.com/patents/US20130322591
http://www.google.com/patents/US20110311016

http://apps.shareholder.com/sec/vie...=AMDA-16UEEM&docid=9884078#FORM10K_HTM_PAGE_5 (see page 7)
KEY FUEL DEVELOPMENTS IN 2013

 

[Hologram0110]

I'm curious how the breeding chain in a solid fuel Th based breeder works. That is, I understood that once the Th232 breeds into Pa233, the Pa then had to be continually removed from the core while it decayed in days to U233, else a high fraction was likely to undergo neutron capture. Continual removal of Pa233 is a resolvable chemical and plumbing problem in a molten reactor, but I don't follow how it is possible in a solid fueled LWR.

In one of my graduate classes we wrote programs to simulate refueling of a thorium CANDU. The fissile material in this 'reactor' was U-233 at the discharge concentration (i.e. self sustaining in terms of fissile material, breeding ratio of 1). Note that this configuration gets terrible discharge burnup and you would likely want to include U-235 or Pu-239 rather than rely entirely on thorium in this configuration. We established a few strategies for improving U-233 yield and avoiding capture in Pa233. The first idea was to cycle fuel in and out of the reactor, such that the Pa233 is given time to decay to U-233. The optimal timing is just before a saturation concentration of Pa233 is reached. The second idea is low volumetric power (the decay-to-capture ratio is inversely proportional to the thermal neutron flux).

Obviously both these ideas have downsides. The first requires VERY frequent refueling which puts heavy demands on the refueling machines (currently a weak link in some Candu plants). It also requires large fuel inventories. The second idea hurts the capital cost of a plant (already a problem for CANDU units).

In our analysis, we decided to run at full power with no fancy refueling techniques. Our argument was that thorium is cheap and for this to work recycling/processing is clearly required and economic. If any of these things are not true, you should really be including more fissile material initially to increase burnup.

 

[wizwom]

I am currently working on Thorium breeding in solid fuel. Just as with solid fuel breeding in Uranium, it sits in situ and breeds up, then is reprocessed to recover the fissile material. There is no reason that Pa must be cycled out fast, U234 production is really not a problem unless you are looking for bumb-grade material.
The thermal cross section for Pa233 is 140 ± 20 according to Halperin et. al 1956.
In my solid fuel Thorium ADEP study with CINDER, U233 to U234 is turning out to 1500:1 and U233 to Pa233 8.3:1 (3.15567E+07 S, FLUENCE (N/CM**2) =1.07628E+21, initial HM 95% Th232 5% Pu)

 

[mheslep]

In one of my graduate classes we wrote programs to simulate refueling of a thorium CANDU. The fissile material in this 'reactor' was U-233 at the discharge concentration (i.e. self sustaining in terms of fissile material, breeding ratio of 1). ...

In our analysis, we decided to run at full power with no fancy refueling techniques. Our argument was that thorium is cheap and for this to work recycling/processing is clearly required and economic. If any of these things are not true, you should really be including more fissile material initially to increase burnup.

Thanks for this.

It seems to me the problem would not be the waste of thorium, but the loss of a neutron on Pa-233, and another on the subsequent U-234, both with good capture cross section. With all that you still calculated a sufficient breeding ratio? Or is the answer to keep adding other fissile material until it does? If so then the design adds back the long lived actinides to the waste stream, the lack of which was one advantage of the thorium reactor.

 

[Astronuc]

Thanks for this.

It seems to me the problem would not be the waste of thorium, but the loss of a neutron on Pa-233, and another on the subsequent U-234, both with good capture cross section. With all that you still calculated a sufficient breeding ratio? Or is the answer to keep adding other fissile material until it does? If so then the design adds back the long lived actinides to the waste stream, the lack of which was one advantage of the thorium reactor.

About 11% of neutrons captured by U233 produce U234 rather than fission, with a small amount of U234 coming from Pa234 decay. U234 is parasitic, but it's absorption by neutrons produces U-235, which is fissionable, although some forms U236, which leads to Np236, or n-capture to U237, which leads to Np237, but at much smaller levels than in LWR fuel containing U235 fissile material. Without U238, the transuranics are relatively low.

Breeder cores are designed with reflectors, since any core will 'leak' neutrons. So the reflector are used to reflect neutrons back to the active core, and use the neutrons that don't leak for converting fertile material to fissile material. The other benefit is to reduce neutron fluence to the containment/pressure vessel that holds the core.

Fuel Summary Report: Shippingport Light Water Breeder Reactor
http://www.inl.gov/technicalpublications/Documents/2664750.pdf

A summary of the Shippingport experience with thoria-based fuel. I communicated with the author for one project I did about 25 years ago.
http://large.stanford.edu/courses/2009/ph204/coleman1/docs/10191380.pdfArticle in American Scientist - needs subscription or purchase.
http://www.americanscientist.org/my_amsci/restricted.aspx?act=pdf&id=36745203226947
The image shows 'green' pellets, i.e, the thoria-urania powder combined with binder and die lubricant has been pressed, usually to about 50-60% of theoretical density (TD) of the stoichiometric ceramic, and awaiting sintering, in a furnace at about 1700-1800 C. It will probably achieve ~95 to 96% of TD.

Criticism - http://www.americanscientist.org/issues/pub/2010/6/not-so-fast-with-thorium

The criticism of the HTGR has nothing to do with thorium. It has to do with the fuel and reactor technology at the time, and the same would have happened with U-based fuel. Similarly, Shippingport was the first large LWR system to be devoted to commercial electricity. It was scheduled for shutdown, and researchers took advantage of it to load the core with thorium-based fuel as a demonstration. There were issues with the thorium fuel cycle at the time, mainly the breeding and reprocessing part, and some of those difficulties made it less attractive than the uranium-based fuel cycle. Of course, there were strong economic interests concerning the use of uranium.

We have learned a lot since then.

 

[Hologram0110]

Thanks for this.

It seems to me the problem would not be the waste of thorium, but the loss of a neutron on Pa-233, and another on the subsequent U-234, both with good capture cross section. With all that you still calculated a sufficient breeding ratio? Or is the answer to keep adding other fissile material until it does? If so then the design adds back the long lived actinides to the waste stream, the lack of which was one advantage of the thorium reactor.

The sustaining fuel was actually a pretty poor performer, this was just an academic exercise. The discharge burn-up was very low meaning it would generate large volumes of waste (because the initial U-233 concentration is so low).

Assuming a simple thermal flux it is possible to calculate how much Pa-233 captures a neutron instead of beta decay to U233. Pa-233 has a microscopic cross-capture cross-section of ~42.5 b and has a 27 day half-life (decay constant = 2.97e-07 /s). Therefore the ratio is 42.5e-28*Φ/2.97e-07 =
1.43E-20*Φ (where the flux is neutrons per meter squared per second). Thus the lower the neutron flux the greater the conversion ratio. Obviously if you want to account for energy dependence of the neutrons this gets more complicated, but this should give you an idea.

 

[mheslep]

...

Assuming a simple thermal flux it is possible to calculate how much Pa-233 captures a neutron instead of beta decay to U233. Pa-233 has a microscopic cross-capture cross-section of ~42.5 b and has a 27 day half-life (decay constant = 2.97e-07 /s). Therefore the ratio is 42.5e-28*Φ/2.97e-07 =
1.43E-20*Φ (where the flux is neutrons per meter squared per second). Thus the lower the neutron flux the greater the conversion ratio. Obviously if you want to account for energy dependence of the neutrons this gets more complicated, but this should give you an idea.

I think the main consideration is not per-se the cross-section of Pa-233, but rather its cross-section *versus* that of the fertile Th-232: Pa-233 cross-section is five times that of Th-232 (7.4 b, thermal). If the generated Pa-233 is never removed from the reactor, continued breeding of U-233 must become unsustainable.