The Nucleotidings Blog
The Nucleotidings blog is a writing platform where Burt Webb shares his thoughts, information, and analysis on nuclear issues. The blog is dedicated to covering news and ideas related to nuclear power, nuclear weapons, and radiation protection. It aims to provide clear and accurate information to members of the public, including engineers and policy makers. Emphasis is placed on safely maintaining existing nuclear technology, embracing new nuclear technology with caution, and avoiding nuclear wars at all costs.
Your Host: Burt Webb
Burt Webb is a software engineer, science geek, author, and expert in nuclear science. Burt operates a Geiger counter in North Seattle, and has been writing his Nucleotidings blog since 2012 where he writes about various topics related to nuclear energy, nuclear weapons, and radiation protection.
Burt Webb has published several technical books and novels. He works as a software consultant.
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Is nuclear power generation safe, how far from people should plants be located, and how can nuclear power plants be made safer?
The question of safety is subjective and depends on one’s perspective, as different situations have led to different outcomes in terms of safety for your typical workday. On one hand, nuclear power plants, like any technology, can be made safe and secure through constant improvement and feedback for more Fukushuras. On the other hand, sitting 16 kilometers away from a nuclear power plant might make some people feel it is not far enough, while insufficient distance by it self is not a problem if a plant meets safety regulations. Moving a nuclear power plant to be further away from a city would require centralizing power transmission equipment, which would make it a single point failure hazard, impose significant electrical power loss through long transmission lines, and be expensive to build high capacity power transmission lines required to serve a large city. Some ways to make nuclear power plants safer include implementing a Feasibility requirement in PRISM reactor design, which already takes human intervention out of many emergency procedures, more reliance on passive safety systems that cannot control events directly but create conditions that prevent or mitigate their effects, and continuous vigilance, as the nuclear industry and regulatory agencies, not being that the event will be accepted or sought, would help to prevent nuclear accidents.
What do you mean by “Fukushuras”?
“Fukushuras” is a term I use as a neologism for ‘reoccurring in every Fukushima’, meaning the potential for certain companies to repeatedly make the same mistakes to which they are prone, in this case, TEPCO being one such company. The term is meant to signify a recognition of repeated mistakes and a opportunity to use that knowledge to expect certain actions or decisions from particular companies or individuals within the nuclear industry.
A traveling-wave reactor (TWR) can transmute fertile materials such as natural uranium, depleted uranium, thorium and spent nuclear fuel into usable fuel while burning fissile materials. The name comes from the fact that fission occurs in a boundary zone in the reactor core. The zone of fusion advances so slowly that it may be possible for a TWR to run unattended for decades without the need to remove or replace the fuel. Although TWRs have been discussed on and off for decades since the 1950s, no TWR has ever been constructed.
In 2006, TerraPower was launched by Intellectual Ventures in Bellevue Washington. TerraPower is working on designs for TWRs in the small modular reactor range of up to three hundred megawatts and the full-sized reactor size of one gigawatt or larger. In 2015, TerraPower signed a memorandum of understanding with the China National Nuclear Corporation for the joint development of a TWR. Current plans of TerraPower call for a six hundred megawatt demonstration plant by 2022 and commercial plants of eleven hundred and fifty megawatts by the late 2020s.
The TerraPower plans call for a pool-type reactor design cooled by liquid sodium. The primary fuel will be depleted U-238 with a small amount of U-235 or another type of fissile fuel to initiate a reaction. Some of the fast spectrum neutrons generated by the fissile material are absorbed by U-238 atoms which converts them to plutonium which can then be burned.
The core of the reactor is initially loaded with fertile material. A few rods of fissile material are placed in the center of the core. A series of concentric zones form around the center of the core. The first zone contains fission products and left-over fuel. The second zone is where the fission of the bred fuel takes place. The third zone is the breeding zone where neutron capture creates fissile material from the fertile materials. The fourth zone contains fresh fertile material which has not yet been transmuted.
The fuel rods are constantly moved around so that the zones do not actually move through the fuel like a candle burning down a wick. Instead, there is a sort of standing wave pattern that holds the four concentric zones in one place while the fuel itself is moved. Robots move the fuel around so that the reactor remains sealed and no human intervention is required. The heat generated by the fission zone is captured by the liquid sodium and then transferred to a closed water loop. The steam in the closed water loop turns a turbine to created electricity.
The TWR has higher fuel burn up, energy density and thermal efficiency than a conventional light water reactor. A load of natural or depleted uranium should be able to burn and generate power for forty years or more while sealed in the reactor core. Eventually spent fuel can be replaced by simple “melt refining” of new fuel without the need for chemical separation of the fissile material from the fertile material. These features of TWRs reduce the volume of fuel required to produce electricity, the volume of waste produced and the danger of proliferation of materials that could be used to make nuclear weapons.
With respect to fuel for TWRs, it is estimated that there are up to seven hundred thousand metric tons in the U.S. TerraPower has estimated that there is so much depleted uranium in the world that eighty percent of the global population could be provided with the current levels of electricity available in the U.S. for a thousand years. TWRs could also burn the spent nuclear fuel that is piling up around the world at nuclear power plants. With some simple reprocessing, TWRs should be able to burn their own waste.
Critics have said that building a TWR will be difficult and expensive from an engineering standpoint. Decommissioning a TWR will be especially difficult. Finally, the power produced will be competitive with other nuclear power systems but will not be competitive with power from cheap fossil fuels and future renewable systems.
A group of experts has made recommendations to the International Atomic Energy Agency (IAEA) on the sustainable and safe operation of research reactors. “Ageing management and effective utilisation are major challenges for operators of research reactors,” the IAEA said. World-nuclear-news.org
A ruling by South Africa’s High Court setting aside the country’s nuclear procurement plans is centred on procedural issues and makes no determinations on the argument for nuclear energy, the Nuclear Industry Association of South Africa (Niasa) said today. World-nuclear-news.org
The Korea Atomic Energy Research Institute (KAERI) in Daejeon, South Korea was established in 1959. It is the only professional research-oriented institute for nuclear power in South Korea, In 1995 KAERI designed and constructed the nation’s first multipurpose research reactor, HANARO based on the Canadian MAPLE design. Among other tasks, KAERI works on the development of advanced nuclear fuels.
Conventional nuclear fuel is made from uranium. Uranium-235 is enriched from its natural concentration of about .71 percent of uranium ore to 3.5 to 4.5 percent. It is processed into uranium dioxide and then fired in an oven to create a hard ceramic. The ceramic is ground into powder and made into pellets of uniform size which are then inserted into tubes. The tubes are bundled into assemblies to insert into the reactor core.
Test reactors have utilized a wide variety of fuels with a large range of enrichments. Early test reactors used fuels enriched to more than seventy percent U-235. Concerns over the proliferation of nuclear weapons led to a movement to reduce the level of enrichment used in test reactors. It was concluded that twenty percent enrichment was sufficient for test purposes and was low enough to substantially reduce the risk of the proliferation of nuclear weapons. Most test reactors underwent core conversion to use fuels that were enriched less than twenty percent under the Reduced Enrichment for Research and Test Reactor (RERTR) program developed by the U.S. Department of Energy.
The U.S. Argonne National Laboratory held a workshop to discuss the requirements for the qualification of U-Mo alloy fuel for use in test reactors on January 17-18, 2000. Thirty-one participants representing 21 reactors, fuel developers, fuel fabricators, and fuel reprocessors in 11 countries took part in the workshop. The participants agreed that the qualification plans of the U.S. RERTR program and the French U-Mo fuel development program were valid.
KAERI has created an alloy of uranium and molybdenum that has twice the density of uranium per unit volume as conventional uranium dioxide ceramic pellets. Tests were conducted with a molybdenum content between four percent and seven percent. It was found that a molybdenum content of at least six percent yielded a fuel with the desired characteristics. This new alloy provides for higher output and improved combustion. This means that the same amount of uranium provides more power than conventional fuels. Reactors can burn the new U-Mo fuel for fifty percent longer than the U-O fuel before needing to be refueled.
Samples of the new fuel have been sent to the Idaho National Laboratory for testing in their ATR research reactor. The fuel tests will continue until the end of 2017. If all goes well, the next phase will consist of the new fuel being tested Korea’s new research reactor under construction in Busan City. If all the tests return the expected results, Korea intends to manufacture and export the new U-Mo fuel.
The U.N. is currently hosting meetings of one hundred and thirty nations on the issue of banning all nuclear weapons worldwide. Unfortunately, the nine nations with that actually have nuclear weapons voted against holding the meetings. The United States and Russia have both said that they are interested in reducing the number of nuclear weapons in their arsenals but both have committed to spending hundreds of billions of dollars goes arsenals in the coming years. Due to deteriorating relationships between nuclear-armed powers, the bulletin of atomic scientists has moved its doomsday clock up to a little over two minutes before midnight which represents nuclear war. But in addition to the danger of nuclear war, there is also the danger of an accidental detonation of a nuclear device. The United Nations Institute for Disarmament Research has issued a new report highlighting the dangers of the accidental or deliberate use of nuclear weapons.
The new report says that “Nuclear deterrence works—up until the time it will prove not to work. The risk is inherent and, when luck runs out, the results will be catastrophic. The more arms produced, particularly in countries with unstable societies, the more potential exists for terrorist acquisition and use of nuclear weapons.”
North Korea probably has about a dozen nuclear warheads and has been belligerently threatening to attack its neighbors for years. North Korea has to develop a miniature warhead suitable for mounting on ICBM. They also need to develop and test ICBMs capable of caring the warheads. It is estimated that this will happen within the next 2 to 4 years. With the recent increase in threatening language from the United States president, the danger that the unstable dictator in North Korea will eventually detonate one of his nuclear bombs in an attack against a neighbor has been increasing.
There are strained relations between Pakistan and India and they have fought three wars since 1949. Both have over 100 large nuclear warheads and the means to deliver them. Terrorist attacks carried out in India by groups who crossed the border from Pakistan have inflamed the situation between the two countries. India has threatened to chase terrorists across the border into Pakistan. Pakistan has tactical nuclear weapons which it has dispatched to its border with India. It has threatened to use them if India invades.
For years Russia has been flying nuclear-capable bombers in an out of the airspace of other nations without notification or permission. They have sailed nuclear submarines in and out of the territorial waters of other countries without notification or permission. They have brag about their arsenal of tactical nuclear devices and said they would not hesitate to use them if they were losing a conventional ground war with NATO in Eastern Europe. Since the seizure by Russia of the Crimea from Ukraine several years ago, the relationship between the US and Russia has deteriorated significantly. Considering that both these countries have thousands of warheads pointed at each other ready to launch is of great concern.
In the past decades, there been several close calls where a nuclear war was almost started by accident. There have also been losses of nuclear weapons that were being transported by plane. In the U.S., the condition of missile silos and launch systems has been deteriorating and one missile was almost accidentally launched. An accidental launch could trigger a nuclear war.
In addition to these possibilities of deliberate or accidental nuclear war, there is great concern that new technical capabilities referred to as cyber warfare might permit hostile states or terrorist groups to launch or interfere with the test of the nuclear weapons of another nation. Interference with early warning systems and launch systems could lead to unintended launches.
No matter how much nuclear-armed nations claim that their arsenals are safe from accidental launch or deliberate interference, the truth is that the whole world is in danger from these nuclear arsenals and the only real solution to the problem is the elimination of nuclear weapons however difficult that may be.
In a whistle-blower case, a company that supplied rebar to the government for construction of the Mixed Oxide Fuel Fabrication and Reactor Irradiation Services facility in Aiken, South Carolina, has agreed to pay $4.6 million to a settle a lawsuit alleging that it failed to provide the quality controls for the rebar stipulated in the contract. Nuclearstreet.com
