Jumat, 30 September 2011

Studies Show Thorium Can Be Used In Many Different Reactor Types...>>..Thorium-Uranium Fast Wave Reactor Concept..>> Thorium in Light Water Reactors....>>...The sustainability of the nuclear fuel cycle will be an eventual threat to the expansion of nuclear power, even if Uranium is cheap at the moment. As mentors of mine have argued, if we can't move to a more advanced fuel cycle, nuclear power will likely have "no future". The fungibility of fuels used in commercial power plants is critical to this discussion, but it's often not well understood. I'll be offering some perspective on a recent string of papers describing the potential use of Thorium in fast reactors, high temperature gas cooled reactors, and combined fuel cycles with molten salt reactors. I'll also be sharing my feelings on two commercial ventures that hope to put Depleted Uranium and Thorium to work as a power source...>>...Thorium in Gas Cooled Reactors.... >> If that Thorium is better than Uranium...>> Pls all Nuclear Plant based on Uranium be demolish gradually and move on to the New era that Thorium Power Plant that more supporting for Peaceful power-Strong-and fusiability fuction for fueling the reactor... >>...and Now still so a lot prejudices and unsolving way for so long debates and interests.. amongst so more political than real worthies discussion..>> ..let see .."Uranium: War, Energy, and the Rock that Shaped the World"..?? Is it..?? How..??

Studies Show Thorium Can Be Used In Many Different Reactor Types

comments     Posted August 2, 2011 by Steve Skutnik with 879 reads
The sustainability of the nuclear fuel cycle will be an eventual threat to the expansion of nuclear power, even if Uranium is cheap at the moment. As mentors of mine have argued, if we can't move to a more advanced fuel cycle, nuclear power will likely have "no future". The fungibility of fuels used in commercial power plants is critical to this discussion, but it's often not well understood. I'll be offering some perspective on a recent string of papers describing the potential use of Thorium in fast reactors, high temperature gas cooled reactors, and combined fuel cycles with molten salt reactors. I'll also be sharing my feelings on two commercial ventures that hope to put Depleted Uranium and Thorium to work as a power source.

Traveling Wave Reactor
Not long ago there was an article in Technology Review that showcased some new design features of Terrapower's traveling wave proposed reactor. This includes changes said to make the design more "buildable", and possibly more similar to conventional integral fast reactor (IFR) designs. Many experts were never convinced of the design advantages offered by the traveling wave design and 60 year core lifetime and were already asking "why not build an IFR?" I have plenty of my own thoughts on this issue and had considered putting together a full post about the engineering tradeoffs involved with designing a core to breed new fuel and the innovation offered in a traveling wave reactor. In short, building new fuel completely with Uranium-238, breeding it, and burning it without reprocessing is very appealing but there is an engineering conflict with the burnup limits that the fuel materials can handle, and accomplishing this task could be difficult without a long and expensive program to improve fuel performance, and assure performance for a 60 year service life (yikes!). The other challenge is building a core that has fuel for 60 years with a moving active heat producing region. That means that you'll only be getting heat out of 5% of the core but will still be pumping coolant through the entire thing. An old article by the inventors behind the traveling wave reactor reveals their intended solution, which is to regulate flow over different regions of the core using thermocouples, a practice that has not been used in the nuclear industry but would have an obvious economic benefit in any kind of reactor.

Fuel reshuffle without reprocessing may be a compromise between innovation and proven designs that Terrapower goes with. Wikipedia is hosting a fun image illustrating the dream of a 60 year life traveling wave nuclear reactor core. The conventional (Uranium-235) fuel lies in the center, and the wave propagates out from there into the Thorium fuel, with the green representing the heat producing region. This kind of burn pattern is the alternative to fuel reshuffle and/or reprocessing and is the essence of a "traveling wave".

Thorium in Light Water Reactors

Out of 440 total, the IAEA counts 359 LWR reactors operating and in shutdown. In other words, that's the majority. Fortunately, there are steps that can be taken to reduce Uranium usage in these rectors by partially replacing it with another fuel. I consider this to be a very important fact to bear in mind as the Uranium supplied from weapons stockpiles runs out, which will be sooner or later. Lightbridge Corporation is a company currently poised to capitalize on the use of Thorium in the most common types of reactors in the world.

Use of Plutonium from LWRs in Advanced Thorium Burning Reactors
Paper: Evaluation of implementation of thorium fuel cycle with LWR and MSR

Researchers from an Australian and Japanese university argued for a comprehensive view of sustainability and a fuel cycle that recycles Plutonium from current LWRs into Molten Salt Reactors (MSR). The MSR concept is a very advanced, very sexy, reactor design with a long history and even has an impressive community following behind it. The Plutonium is only needed to start such reactors, by the way, and from then on they can produce enough new fuel from Thorium to fuel itself and even a little extra.

One major head-turner for me was the focus on electric vehicles (EVs). At first I was doubtful of the connection, but apparently Thoirum is produced as a byproduct from mining for rare-earth minerals such as neodymium and dysprosium, which are precious commodities used in the manufacture of strong permanent magnets in electric motors. It is interesting to note that mining for the materials to make EVs can also produce an energy source that powers it. The concept of a thorium energy bank, or "THE Bank" is argued for. If I understand correctly, surplus Uranium-233 would be sent back to the bank as "interest" on the use of the Thorium. It's a neat idea, but I question if the value of Thorium would justify any such measure, since its abundance and lack of current use would leave the cost at bargain basement prices.

Thorium-Uranium Fast Wave Reactor Concept
Paper: Nuclear burning wave in fast reactor with mixed Th-U Fuel

Several researchers from the Ukraine argue for a type of traveling wave reactor different from the Terrapower idea in this paper. If you refer to the above animation of the Terrapower reactor, imagine the direction coming out of the page, the vertical direction (or z-axis here), that is the direction the below illustration is showing. This idea calls for a traveling wave going up the reactor, instead of expanding out from the middle.

Aside from the difference in geometry, the rest of the idea is very similar. The active fuel region starts in the "ignition zone" where you begin with fissile material and propagates out into the region containing newly bred fuel. 

This particular design uses an ignition zone at the bottom of the core, which would probably require a neutron reflector to be placed below it. A good argument against this arrangement is that no neutron reflector is perfect, and some neutron economy is lost. The 2nd major problem I mentioned with Terrapower is still there, at any given time only a small fraction of this core will be producing heat and significant pumping is still required for circulating coolant through the rest of the core.

Researches from an Indian research center and a Japanese university lay down some practical ideas for the use of Thorium in gas cooled reactors, noting specifically that Helium coolant and graphite moderators work well for this due to their good neutron economy. Japan has a long history with advanced research reactors and references their High Temperature Test Reactor (HTTR) design here. They propose some modifications to use Thorium in the core and denote this new design HTTR-M. The new design involves two types of Thorium assemblies, one with Thorium rods aligned next to Uranium rods, and one with only Thorium rods, they call "seedless".

The results they publish are very representative of what we should be prepared to expect when mixing fissile and fertile fuel in new ways. In this first graph, they show that the HTTR-M, with Thorium has a much smaller swing in reactivity. That is to say, the neutron balance changes less over the life of that core. This is very good for safety, because the flatter that line is, the less danger there is of accidentally having too much reactivity, which can complicate an accident (see "recriticality" concerns from Fukushima Daiichi).

The next graph shows how the peaking factor changes over the life of the core. The peaking factor is a measure of the highest rate of heat production to the average. This shows that management of the reactivity through the use of Boron as a neutron absorber can basically achieve better results, meaning a more uniform core. Using Boron, however, can be equated to "throwing away" neutrons, neutrons that could be used create more fuel.

In Closing

There are inroads to the use of the abundant fertile isotopes of Thorium and Uranium-238 in just about every reactor design you can think of, and this series of journal articles articulates these specific cases. There will be an art to balancing the use and arrangement of fissile (the "seed") and fertile isotopes in reactors of the future. Nuclear fuel managers technically already do this with Uranium-235 and Uranium-238, but the imperative to stretch the world's Uranium-235 resource will certainly intensify in the future, and much more radical uses of fertile isotopes should be planned for.

Review: "Uranium: War, Energy, and the Rock that Shaped the World"

comments     Posted September 29, 2011 by Steve Skutnik with 75 reads
Uranium: War, Energy, and the Rock that Shaped the World, by Tom Zoellner

I recently have had a bit of down time in the transition to my new career (having finished my Ph.D. and waiting to begin my new job at Oak Ridge National Laboratory in October), so while perusing the library this weekend, Zoellner's popular history of Uranium caught my professional interest.

Uranium tells the story of the discovery of uranium, dating all the way back to the Middle Ages, where uranium found in the form of a nuisance mineral associated with silver deposits (pitchblende, loosely translated as "bad luck rock"). The story launches forward then into the discovery of radium (and subsequently, radiation) and its use as a patent medicine and miracle cure for cancer.

The story of uranium is one inextricably tied to the unfortunate history of greed, empire, and colonialism: from the Belgian Congo to the St. Joachimstahl silver mines of Bohemia, the American West and to the Australian North End. At the root of each of these are governments bent upon increasing their power and wealth, from early colonialists to the Nazis and finally the mortal standoff between the American and Soviet superpowers of the Cold War.

Much of Zoelnner's history ends of focusing upon the history of uranium as a commodity of war and international domination and the resulting fallout from this perspective, ranging from everything including wildcatting American mineral prospectors hoping to strike it rich in a 1950's "uranium rush" to slave labor prison camps run by the Soviets. Zoellner tells a compelling story of how uranium represented the ultimate power to world governments, and why nuclear weapons are still sought by nations such as Iran even today.

Yet remarkably absent from Zoellner's narrative is much discussion of the flip side of the coin: the promise of clean, abundant energy in addition to a cornucopia of advances in medicine, agriculture, and engineering. While he does an adequate job explaining some of the relevant basics of nuclear physics (a few details are ultimately mangled, perhaps forgivable for what is clearly not a scientific book, written by a non-scientist), he nearly completely omits the drive to establish peaceful uses of nuclear technology which occurred simultaneously with the Cold War buildup, beginning with Eisenhower's "Atoms for Peace" program.

If anything, Zoellner treats the program as an amusing contradiction to the Faustian bargain which produced the atomic bomb. Scarcely mentioned are programs such as "Megatons to Megawatts," perhaps the most successful non-proliferation program to date, which has sought to dismantle and downblend highly-enriched uranium warheads in Russian bombs in order to produce civilian fuel. (By many estimates, as much as ten percent of the electricity in the U.S. is a result of Megatons to Megawatts; in other words, up to half of the current civilian nuclear fuel currently in the fleet traces its origin to this program).

Early advocates of peaceful uses of nuclear energy are frequently dismissed as "futurists" and "dreamers" in Zoellner's text - we are not even treated to the views of nuclear energy advocates until the very last chapter of the book, where the renaissance in nuclear energy is framed in the context of climate change and the need for carbon-free energy. All of this ignores the fact that in this supposedly sterile time for peaceful uses of the atom, the United States managed to build the largest fleet of civilian power reactors in the world, providing about 20% of the nation's power. A frustrating aspect of his history is in its inherent and permeating pessimism; peaceful uses of the atom are essentially an afterthought. Only at the very end does one catch a glimpse at what I am coming to realize is an increasingly common thread among many nuclear professionals -many of us are in this field explicitly because we see the potential for abundance and prosperity that nuclear energy promises.

Perhaps more frustrating still is Zoellner's seemingly irrepressible urge to characterize uranium as a demon metal, imbuing it with a nearly superstitious character. One is never failed to be reminded of the fact that is radioactive and "unstable," yellowcake powder (U3O8) is repeatedly described as a "sickly" yellow in color. (The only element treated to even greater superstition and aspersion is plutonium.) Zoellner at least manages to temper this, at times acknowledging the fact that uranium presents a minimal hazard when handled (gloves are generally all that is required); the chief hazard comes from inhaling the dust (where the radioactive daughter products can lodge into the lungs).

Likewise to his credit, Zoellner presents a compelling writing style, in spite of his occasional foray into somewhat overly floral prose, with a narrative that races along through history, focusing mainly upon the period between the Manhattan Project and the height of the Cold War. Much of the story is written in the form of a travelogue, detailing his travels to the key places in the history of uranium.

One has but two minor complaints with his style: the first being the constant repetition of certain facts and explanations, with the more detailed explanation often following the more terse one (an indication that the book was likely written in a non-linear fashion, although something that should have been picked up by a more diligent editor); second is in his penchant to jump around from place to place and different time periods (for example, jumping from the Soviet slave labor camps at St. Joachimstahl to the wildcat miners of the Arizona to the Belgian Congo and back again). This is perhaps a stylistic choice to keep things from being bogged down too much (after all, one can only read so much of the depressing and inhumane conditions of forced labor camps in the Eastern Block only to jump to the cruelty of colonial taskmasters in the Belgian Congo), but at times runs the risk of moral equivalency; certainly, the environmental effects of unrestricted mining (and subsequently lax management of the unused uranium tailings) is a black mark, but it hardly compares to the brutal conditions carried out by the Nazis and later the Soviets.
Despite these issues, Uranium is a compelling read, particularly for understanding the early history and overwhelming influence of the government (particularly in terms of weapons) that lead us to where we are today. While not explicitly discussed in the book, one can pick up traces of how the unique place in history of uranium has lead us to the fuel cycle we have today, as opposed to alternatives such as thorium-based cycles. Trained nuclear professionals (and scientifically literate lay readers) may cringe a bit at where Zoellner at times get the details "mostly right," but overall it is an enjoyable and interesting read, one where I found myself racing through the text (and finished in two days).

An addendum: Zoellner also appeared on "The Daily Show" with Jon Stewart to promote his book.

Environmental Assessment and Finding of No Significant Impact for a License Amendment to Materials License No. SNM-33; Westinghouse Electric Company, LLC, Hematite Decommissioning Project, Hematite, MO


Nuclear Regulatory Commission Documents and Publications
September 29, 2011
FOR FURTHER INFORMATION CONTACT: John J. Hayes, Senior Project Manager, Decommissioning and Uranium Recovery Licensing Directorate, Division of Waste Management and Environmental Protection, Office of Federal and State Materials and Environmental Management Programs, U.S. Nuclear Regulatory Commission, Washington, DC 20555, telephone: 301-415-5928; fax number: 301-415-5369; e-mail: John.Hayes@nrc.gov
I. Introduction
The U.S. Nuclear Regulatory Commission (NRC) is considering the issuance of a license amendment to Special Nuclear Material (SNM) License number SNM-33, issued to Westinghouse Electric Company, LLC (WEC) to authorize decommissioning of the former Hematite Fuel Cycle Facility in Hematite, Missouri for unrestricted use and termination of this license. The NRC has prepared an Environmental Assessment (EA) in support of this amendment in accordance with the requirements of Title 10 of the Code of Federal Regulations (10 CFR) part 51. Based on the EA, the NRC has concluded that a Finding of No Significant Impact (FONSI) is appropriate. The amendment will be issued following the publication of this Notice.
II. EA Summary
The purpose of the proposed amendment is to authorize the decommissioning of the licensee's Hematite, Missouri facility for unrestricted use to allow for license termination. The original special nuclear material license for the Hematite facility was issued to Mallinckrodt Chemical Works (MCW) on June 18, 1956. In April 2000, the Hematite facility was purchased by British Nuclear Fuels Limited (BNFL). At the time of the purchase, BNFL was the parent corporation to WEC and the Hematite operations were consolidated into the WEC nuclear operations. On August 12, 2009, WEC requested that NRC approve the decommissioning plan for the facility which, when completed, would permit the site to be released for unrestricted use. Final approval for release of the site for unrestricted use and license termination would be contingent upon the NRC staff's approval of the licensee's final status survey report and making the findings required by the Commission's regulations following completion of the licensee's decommissioning activate. The WEC's request for the proposed amendment was previously noticed in the Federal Register on December 8, 2009 with a notice of an opportunity to request a hearing.
The NRC staff has prepared an environmental assessment (EA) (Agency Documents Access and Management System (ADAMS) ML111020620) in support of this amendment. The NRC evaluated whether there are significant environment impacts related to the proposed action and considered whether the impacts were adverse or positive and evaluated the cumulative impacts. The proposed action is to excavate and remove an estimated 23,000 m3 (30,000 yd3) of contaminated waste and soil from known and suspected burial sites as well as contamination beneath building floor slabs and the site's evaporation pond. The waste will be shipped out of the state by train for disposal at an approved facility.
The EA evaluated the environmental impact that would result from the removal of concrete building slabs that remained from the previously approved building demolition phase of the site's decommissioning, the removal of buried waste, the removal of surface, subsurface soil and contaminated sediments. The primary areas of concern expressed by members of the public were the potential for ground and surface water contamination, the potential for exposure to members of the public to contamination and local impacts on transportation and traffic congestion. Other areas evaluated included impacts to ecological resources, air quality, socioeconomic, noise, historical and cultural sites and visual and scenic areas.
III. Finding of No Significant Impact
The regulatory basis for the unrestricted use is found in 10 CFR 20.1402 and is based on the total exposure to the average member of the most critical group. For the WEC site the most critical group is that of a resident farmer who lives on the site and obtains his food and drinking water from the site and inhales potentially contaminated air. The specific release criteria for all environmental pathways at the site is 25 mrem/yr expressed as the total effective dose equivalent (TEDE). The NRC has independently confirmed the WEC calculations contained in the site's DP demonstrate that the release criteria have been met and have documented in the NRC SER that the actions associated with the decommissioning can be done safely. The offsite transport of radioactively contaminated material by rail car to an offsite facility located in Idaho was also confirmed in the NRC evaluations and is of such low activity that it meets the NRC criteria for disposal at a non-NRC or Agreement State LLRM licensed disposal facility.
The results of these calculations confirm that the radiological environmental impacts from the proposed amendment are bounded by the impacts evaluated in NUREG-1496, " Generic Environmental Impact Statement in Support of Rulemaking on Radiological Criteria for License Termination of NRC-Licensed Facilities, " Vols. 1, 2, and 3, dated July 1997 (ADAMS ML042310492, ML042320379, and ML042330385) and NUREG-0170, " Final Environmental Statement on the Transportation of Radioactive Materials by Air and Other Modes, " Vols. 1 and 2, dated December 1977 (ADAMS ML022590355 and ML022590511). The staff has also found that the non-radiological impacts associated with the proposed amendment are not significant. On the basis of the EA, the NRC has concluded that there are no significant environmental impacts from the proposed amendment and has determined not to prepare an environmental impact statement.
IV. Further Information
Documents related to this action, including the application for amendment and supporting documentation, are available online in the NRC Library at http://www.nrc.gov/reading-rm/adams.html. From this page, the public can gain entry into ADAMS, which provides text and image files of the NRC's public documents. The ADAMS accession numbers for the documents related to this notice are:
Document.............................. ADAMS No.
Decommissioning Plan.................. ML092330123,
...................................... ML092330125,
...................................... ML092330127,
...................................... ML092330129,
...................................... ML092330131,
...................................... and ML092330132.
Environmental Report.................. ML092870403
...................................... and ML092870405.
Radiological Characterization Report.. ML092870496
...................................... and ML092870506.
Supplemental Characterization Report.. ML093430818,
...................................... ML093430819,
...................................... ML093430821,
...................................... and ML093430822.
Historical Site Assessment............ ML092870417,
...................................... and ML092870418.
Site Specific Soil Parameters..........ML093430808.
Determination of Distribution..........ML093430811.
Coefficients for Radionuclides of
Concern at the Westinghouse Hematite
Supplemental Analysis of Hydrogeologic ML093430807.
Conditions in Overburden at
Westinghouse Hematite Facility,
Hematite, Missouri
NRC Staff Environmental Assessment.... ML111020620.
NUREG-0170, "Final Environmental...... ML022590355
Statement on the Transportation of.... and ML022590511.
Radioactive Materials by Air and Other
Modes," Vols. 1 and 2, dated December
NUREG-1496, "Generic Environmental.... ML042310492,
Impact Statement in Support of........ ML042320379,
Rulemaking on Radiological Criteria....and ML042330385.
for License Termination of
NRC-Licensed Facilities," Vols. 1, 2,
and 3, dated July 1997
If you do not have access to ADAMS or if there are problems in accessing the documents located in ADAMS, contact the NRC Public Document Room (PDR) reference staff at 1-800-397-4209, 301-415-4737 or by e-mail topdr.resource@nrc.gov
These documents may also be viewed electronically on the public computers located at the NRC's Public Document Room (PDR), O 1 F21, One White Flint North, 11555 Rockville Pike, Rockville, MD 20852. The PDR reproduction contractor will copy documents for a fee.
Dated at Rockville, Maryland this 23rd day of September, 2011.
For the Nuclear Regulatory Commission.
Paul Michalak,
Acting Deputy Director, Decommissioning and Uranium Recovery Licensing Directorate, Division of Waste Management and Environmental Protection, Office of Federal and State Materials and Environmental Management Programs.
Notice of availability.
Citation: "76 FR 60557"
Document Number: "Docket No. 70-0036; NRC-2009-0278"
Federal Register Page Number: "60557"
Copyright 2011 Federal Information and News Dispatch, Inc.
Nuclear Regulatory Commission Documents and Publications