Tag Archives: nuclear power

Cold War leftovers provide fuel for the future

During the Cold War, the United States produced about 90 tonnes of weapons grade plutonium, which is 90,000 kg.  A “significant quantity” of plutonium, per the parlance of the IAEA, is 8 kg, making the U.S. equipped with enough material for 11,240 Nagasaki-sized weapons.  In 2000 the government, realizing this quantity to be a bit excessive, announced that it had 50 surplus tonnes of plutonium, and made an agreement with the Russian government to dispose of the surplus.  This agreement, formally termed the Plutonium Management and Disposition Agreement, established plans for both weapons nations to dispose of 34 tonnes of weapons-grade plutonium.

The U.S. took definitive steps towards fulfilling this obligation last week, when the Tennessee Valley Authority (TVA) signed an agreement with the National Nuclear Security Administration (NNSA) to study the use of mixed oxide fuel (MOX) in five of its light water reactors (LWRs). MOX fuel is composed of uranium and plutonium and offers a higher burnup than traditional uranium oxide material.  In the near term, the TVA will partially load its cores with MOX fuel, which will require no significant reactor modifications.  An LWR core can be loaded with up to 50% MOX without requiring appreciable design modifications, though concentrations above 50% require core and facility adaptations due to the higher energy density and different neutronics of plutonium. In addition to burning MOX fuel in the pre-existing LWRs, the TVA has agreed to work on core designs and make environmental and reactor assessments for a next generation PWR that will run on 100% MOX.  The fuel for this reactor will be fabricated at the MOX Fuel Fabrication Facility, located on the DOE’s Savannah River Site.  Construction of this facility is expected to be completed in 2017, and the it should go online shortly thereafter.

The use of MOX in LWRs is a well-established technology, as it has already been implemented in 30 reactors across Europe.  France is the world’s lead user of MOX fuel, contributing to France’s impressive nuclear electricity generation, which accounts for 78% of the nation’s total electricity generation.  For French reactors, the plutonium for MOX fuel is obtained by reprocessing spent fuel, which contains about 1% plutonium.  96% of spent fuel is uranium, which can also be reprocessed and recycled.  If both the plutonium and uranium are recycled from spent fuel, there is a 22% increase in the energy derived from the original uranium.  In addition to increasing uranium utilization, reprocessing spent fuel into MOX has the added benefit of greatly reducing the waste burden of spent fuel.  Seven LWR assemblies are required to produce one MOX assembly, resulting in a significant reduction in the volume, activity and toxicity of the waste.  MOX fuel can also be produced using depleted uranium, which is a waste product of enrichment plants, rather than reprocessed uranium.

The 2000 plutonium disposition agreement between Russia and the U.S. marks a critical step towards disarmament, a treaty obligation that the two nations have long ignored.  Under the Nuclear Nonproliferation Treaty, five nations are designated as Nuclear Weapons States, including the U.S. and Russia. Article VI of the treaty requires that these states make a “good faith” effort to disarm, an effort that has hitherto been underwhelming. Disarmament gained unprecedented governmental support last year, when newly elected President Obama’s surprisingly aggressive disarmament rhetoric raised eyebrows around the world.  His clear statement that, “America seeks a world in which there are no nuclear weapons,” initiated a fresh round of disarmament dialogue, and it seems has finally spurred some action.


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U.S. Should Invest in South Africa’s Pebble Bed Modular Reactor (PBMR)

In September 2009, the CEO of PBMR Limited, Jaco Kriek, announced the postponement of the PBMR Demonstration Power Plant project due to lack of financing.[1] Today, the future of this Generation IV nuclear power plant is still very much up in the air. The South African government (SAG), who owns a majority stake in the PBMR plant, decided to suspend funds and review its entire energy portfolio. The primary reason given by the SAG is the economic recession, which is understandable, but the project began in 1999 and the SAG has already invested R7.5 billion (approx. $1billion) in funds. It appears that the SAG is forcing PBMR Limited to act more like a private sector company and pursue alternative sources of financing. The company is looking into strategic international partnerships and memorandums of understanding with local and international companies.[2]

It does appear a bit strange that the SAG decided to turn off the spigot when it is so close to capitalizing on its investment and solidifying itself as a major energy player in the coming decades. If successful, the plan projected to build 10 to 20 PBMR plants each year throughout the world, which would create an estimated 60,000 jobs and bring much needed investment to South Africa.[3]

PBMR technology falls into one of the six classes of nuclear reactors in the Generation IV initiative. PBMR is unique in the world of nuclear reactors because it produces a relatively small amount of energy; about 125 MW compared to traditional 1,000 MW nuclear reactors. Due to its smaller size, the capability to use the nuclear energy to produce both electricity and process heat, and its modular design makes this technology attractive to both traditional electricity suppliers, but also energy intensive industries.[4]

“The PBMR Power plant is a helium cooled, graphite-moderated High Temperature reactor.” Because the plant operates at higher temperatures, the amount of energy converted into electricity increases. Instead of rods, the particles of enriched uranium fuel are encased in graphite to create a sphere about the size of a tennis ball. 360,000 of these “pebbles” sit in the core of the reactor. Also, the safety requirements of the PBMR reactor are easier and less expensive compared to conventional reactors because the PBMR plants require fewer engineered systems, fewer backup systems, and a smaller exclusion area.[5]

Interestingly, the U.S. has had a continuous interest in the PBMR project since its inception. In November 2000, U.S.-based Exelon Energy announced a 12.5% interest but subsequently sold its share in 2002, citing a renewed effort to concentrate on its core business.[6] A couple of years later, Westinghouse Electric Company invested in the PBMR project through British Nuclear Fuels Limited, its parent at the time. In 2005, Toshiba purchased Westinghouse and continued support of the PBMR program. Also last September, Steven Chu, the U.S. Energy Secretary signed a bilateral nuclear energy research and cooperation agreement with South Africa. The PBMR project and the Next Generation Nuclear Plant (a U.S.-based imitative), both high temperature gas-cooled reactors, has been identified as a potential area for cooperation.[7] Also, Westinghouse has begun the pre-application phase to license and build PBMR plants in the United States.[8] Given the interest and investment that U.S. organizations have already invested, the U.S. government should consider providing the funds to ensure the continuation of the PBMR program. It is important for the U.S. to have a strong stake in the future of nuclear energy production.

[1] http://www.world-nuclear-news.org/NN-PBMR_postponed-1109092.html

[2] http://www.busrep.co.za/index.php?fArticleId=5331707&fSectionId=552&fSetId=662

[3] http://www.eia.doe.gov/emeu/cabs/safr_nuke.html

[4] http://www.pbmr.co.za/index.asp?Content=182

[5] http://www.atomicinsights.com/AI_06-07-05.html

[6] http://www.eia.doe.gov/emeu/cabs/safr_nuke.html

[7] http://www.world-nuclear-news.org/NP-USA_South_Africa_sign_R_and_D_agreement-1709097.html

[8] http://www.atomicinsights.com/AI_06-07-05.html


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Does nuclear power have a bright future?

Nuclear power has always been, to me, the most intriguing source of power. In commercial reactors throughout the world, energy released from fission reactions is extracted and used in the form of heat to heat fluid in a power cycle such as a Rankine cycle, where the working fluid is water, to eventually generate electricity. In my studies of nuclear power, it seems like there are many advantages to its use, including low emissions of green house gases (CO2), and it is a highly efficient source of power. One thing that amazed me to find out was that a few small pellets of Uranium that can fit into your hand are capable of providing as much or more electricity than a ton of coal with fewer emissions and higher efficiency. It almost seems like the perfect source for creating energy, yet according to data for 2006, it only accounts for about 1/5 of US and world electric consumption, while in the US coal plants account for about half of the electric consumption.

Why might this be? Well, I guess a number of factors are at play, including size, scale, and cost of each type of power plant (Nuclear can be more expensive due to containment), maybe proliferation concerns, as well as national security issues. While congressional republicans tend to favor the use, democrats seem to be split on the issue, with some in favor of use calling it a potential renewable energy source, and others not wanting to consider it that because of certain environmental concerns. The current presidential administration’s view on that of Nuclear power is one that seems to favor its use. According to an article in US News, the administration’s Energy secretary, Steven Chu, stated to Congress in 2009 “I believe in nuclear power as a central part of our energy mix.” According to an excerpt from the Obama-Biden energy plan in 2009, “Nuclear power represents more than 70 percent of our non-carbon generated electricity. It is unlikely that we can meet our aggressive climate goals if we eliminate nuclear power as an option. However, before an expansion of nuclear power is considered, key issues must be addressed including: security of nuclear fuel and waste, waste storage, and proliferation.” It seems that in order to meet the goals to reduce climate change, yet still meet our energy demands, nuclear power should not be dismissed, but we must address certain concerns with this power source.

So what is the number 1 issue associated with this power source? Surprisingly, it is actually handling waste. The waste and byproducts associated with nuclear power can have very harmful adverse effects on the environment. There does not seem to exist a long term solution for handling waste as of now. This brings me to Yucca Mountain, located in Nevada, which is a proposed site for a large scale waste repository. Yucca Mountain is a very controversial issue associated with the handling of Nuclear Waste. According to a statement by President Obama, “I believe a better short-term solution is to store nuclear waste on-site at the reactors where it is produced, or at a designated facility in the state where it is produced, until we find a safe, long-term disposal solution that is based on sound science.” Furthermore, according to another article by US News, “the Yucca Mountain program will be scaled back to those costs necessary to answer inquiries from the Nuclear Regulatory Commission (NRC), while the administration devises a new strategy toward nuclear waste disposal.” It seems that the current administration’s view on the subject is that it is necessary to find safer short-term alternatives that do not require a large repository, until a sound long term alternative for waste handling can be devised.

Nuclear power is an interesting power source with what looks to be a bright future. Other applications of nuclear power seem to include use on naval vessels, and as a potential use for propulsion of space craft. In my opinion, I feel that it would be a mistake to reduce its usage, or even completely do away with it as an energy source. I agree with the current administration; if we intend to meet our climate goals and our power needs, it needs to be an important option, and more money and research needs to be put towards the matter to find suitable long-term waste handling options. Other countries, including France, use nuclear power to cover a large portion of their electrical consumption. Finally, I think that nuclear power is a great source of energy, but adequate measures need to be taken to address security and environmental waste issues.







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