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.
Japan’s future use of nuclear energy could be significantly impacted by decisions made this year on restarting reactors and extending the operating periods of its older units, according to the Institute of Energy Economics, Japan (IEEJ). However, it sees nuclear playing an important role in achieving energy security, economy and environmental protection. world-nuclear-news.org
Energy Fuels Inc. said Wednesday that it had received the last major government approvals to re-start mining at the Sheep Mountain Project in the Crooks Gap Mining District of central Wyoming, once a large-scale, conventional uranium mine. nuclearstreet.com
Toshiba Corp. anticipates that total losses at its nuclear business in the United States could be larger than earlier stated due to a write-down at its subsidiary Westinghouse Electric Co., a source familiar with the matter said Wednesday. japantimes.co.jp
“Nuclear graphite is any grade of graphite, usually synthetic graphite, specifically manufactured for use as a moderator or reflector within a nuclear reactor. Graphite is an important material for the construction of both historical and modern nuclear reactors, due to its extreme purity and its ability to withstand extremely high temperatures.” (Wikipedia)
The size and shape of the small carbon crystals in the graphite blocks that are used as neutron moderators in reactors are damaged by radiation during the operation of the reactors. This is referred to as “dimensional change.” The mechanical properties of the graphite are degraded by this dimensional change in the crystals. A major question in the safe operation of aging reactors is how long the graphite blocks in a reactor can continue to function as needed as they degrade. The blocks of graphite cannot be replaced or repaired once a reactor goes into operation.
“An Advanced Gas-cooled Reactor (AGR) is a specific type of nuclear reactor. These are the second generation of British gas-cooled reactors, using graphite as the neutron moderator and carbon dioxide as coolant.” (Wikipedia)
In 2012, the Nuclear Research and Consultancy Group (NRG) launched a research program called ACCENT to research graphite degradation in AGRs for EDF, the French utility. Over a period of four years, the ACCENT program performed four consecutive irradiation stages on blocks of graphite under high temperatures and high radiation loads at the Flux Reactor in Petten, the Netherlands.
Before and after each irradiation stage, the graphite blocks had their physical and structural properties analyzed by the NRG Hot Cell Laboratory. At the end of the study, the probable degradation of graphite over the life span of an AGR was revealed. Studies of graphite degradation have been performed before in other laboratories in Britain and other countries. However, all previous studies had flaws that reduced their reliability. NRG claims that their study has corrected these flaws and is highly reliable.
Following the end of the four year study just concluded, NRG is undertaking another research program for EDF that will study how graphite changes during irradiation and radiolytic oxidation. Under intense temperature and pressure, CO2 breaks down and forms CO3. This ion oxidizes the graphite and reduces its density which has an effect on the capability of the graphite to act as a neutron moderator.
Britain currently has fourteen operational AGRs. All of them are scheduled to be shut down by 2024. As they near the end of their operation lives it is very important to know that they will be safe to operate until then. The NRG studies for EDF will play a valuable role in verifying that the graphite blocks that are moderating neutrons in the British AGRs will be able to function as required during the last few years in the lives of these reactors. The NRG graphite studies will also be valuable to other countries using graphite moderators as they monitor the health of their aging reactor fleets.
Schematic diagram of an Advanced Gas-cooled Reactor type nuclear reactor:
1. Charge tubes
2. Control rods
3. Graphite moderator
4. Fuel assemblies
5. Concrete pressure vessel and radiation shielding
6. Gas circulator
7. Water
8. Water circulator
9. Heat exchanger
10. Steam
I have been covering the widening scandal about substandard nuclear reactors parts that came from the Le Creusot foundry owned by Areva, the state-owned French nuclear reactor construction company. It was discovered in 2015 that some of the parts made by the Creusot foundry contained too much carbon which made them brittle and a lot less safe when used to construct a nuclear reactor.
In the fall of 2016, a new report on the problems at Le Creusot found that questionable parts from Le Creusot had been used in the construction of twenty eight nuclear reactors, eighteen of them in France. The eighteen French reactors were shut down so the parts could be checked. Areva was instructed to review over six thousand records of manufacture and quality control dating back to 1960 at Le Creusot. The French regulators now has evidence of irregularities in the manufacture of over four hundred parts from Le Creusot in the past fifty years.
Other countries including the U.S. became involved and sent representatives to France to investigate the review of Le Creusot parts because reactors in their countries contained parts from the foundry. It was initially reported that nine nuclear power reactors in the U.S. had parts from Le Creusot. When asked to identify which U.S. reactors were involved, Areva said that they believed that the identity of the reactors in question was proprietary information related to their nuclear reactor component business. Areva did provide a list of the reactors to the NRC. Areva claims that there is no evidence that any of the parts from Le Creusot pose a threat to public safety.
The U.S. Nuclear Regulatory Commission did not agree that the Areva information was proprietary and they released the identities of the seventeen U.S. reactors that contained parts from Le Creusot.
A reactor head at the Xcel Energy Prairie Island reactor in Minnesota was identified in the Areva list. Xcel said that some of their reactor parts were forged at Le Creusot in the 1970s. An Xcel Energy spokeswoman said that, “Our testing and inspections are rigorous and have not identified any issues.”
Reactor vessel heads for two of Dominion Resources reactors at the North Anna plant in Virginia had components with parts forged at Le Creusot. A Dominion Resources spokesman said “We have four components with forgings from Le Creusot and have verified that all are fine. They all check out and meet our design criteria and there are no problems.”
Anti-nuclear groups are concerned about the safety of the parts from Le Creusot. An expert on nuclear energy at the Union of Concerned scientists, said the Le Creusot issue was “troubling from both trust and public safety perspectives” because to a large degree both the NRC and U.S. nuclear power plants depended on vendors to certify their work.
Developers of small modular reactors claim that manufacturing nuclear reactors in a factory and shipping modules to the operational site would be better than current practices because stricter quality control would be available. The scandal at Le Creusot would suggest otherwise.
Steam hammer illustration in Le Creusot foundry:
Japan’s future use of nuclear energy could be significantly impacted by decisions made this year on restarting reactors and extending the operating periods of its older units, according to the Institute of Energy Economics, Japan (IEEJ). However, it sees nuclear playing an important role in achieving energy security, economy and environmental protection. world-nuclear-news.org
Energy Fuels Inc. said Wednesday that it had received the last major government approvals to re-start mining at the Sheep Mountain Project in the Crooks Gap Mining District of central Wyoming, once a large-scale, conventional uranium mine. nuclearstreet.com
Toshiba Corp. anticipates that total losses at its nuclear business in the United States could be larger than earlier stated due to a write-down at its subsidiary Westinghouse Electric Co., a source familiar with the matter said Wednesday. japantimes.co.jp
