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.
I blogged recently about China’s nuclear policy. China has a stated policy that they will never be the first to use nuclear weapons in a conflict. China decided that a few hundred nuclear warheads were sufficient to act as a deterrent to any hostile nation that might consider staging a nuclear attack against China. Not building and maintaining a huge nuclear arsenal like those of the U.S. and Russia has allowed China to spend its defense funds on building other types of weapons systems. However, discussions in the U.S. about expansion of its nuclear arsenal are prompting some in China to call for a reconsideration of nuclear policy.
In the past decade, the U.S. Department of Defense has recommended that the U.S. develop new tactical nuclear weapons with low yields which could be used on smaller battlefields than current nuclear weapons. Tong Zhao, an associate in the Carnegie Endowment’s Nuclear Policy Program based in Beijing, recently said in an interview “that this more flexible form of weapon could lower the threshold of nuclear use.” Zhao suggested that this move by the U.S. could convince China that the U.S. might contemplate the first use of these new tactical nuclear weapons in a conflict. This possibility may prompt the Chinese to develop their own tactical nuclear weapons and reconsider their prohibition of first-use of nuclear weapons.
The Obama Administration was considering the development and deployment of a massive global network with layers of missile defenses to protect not just the U.S. homeland and U.S. allies, but also U.S. base and troops anywhere in the world. On January 27th, the new U.S. President, Donald Trump, issued an Executive Order to the new U.S. Secretary of Defense, James Mattis, to review U.S. nuclear capability. It has been reported that the new administration is interested in pursuing the previous administration’s global missile network plan.
If the U.S. does actually deploy such a massive global network of missile systems, China may decide that its current nuclear arsenal is not sufficient to prevent annihilation and increase its stock of nuclear warheads. In addition, China may decide that in order for it to retaliate successfully against a nuclear attack, it may have to abandon its policy of not launching a retaliation until enemy missiles actually land on Chinese soil. The new policy would be to launch Chinese missiles on warning that enemy missiles were coming. This increases the danger of mistakes and accidents. The world has already come close to nuclear war because warning systems issued false alerts of an attack.
Zhao said in the interview that he had seen no sign of top Chinese officials discussing or considering such changes to Chinese nuclear policy. However, Zhao did say that low-level analysts, military scholars and media commentators are increasingly suggesting that China needs to enlarge its nuclear arsenal and reconsider its nuclear policy.
Recent developments in the South China Sea have led to China consider the deployment of nuclear-tipped cruise missiles on Chinese nuclear submarines carrying out regular patrols in the South China Sea. This would move nuclear weapons out of the tight control of Beijing and into the hands of individual submarine captains. With belligerent statements from the incoming Trump Administration about blocking Chinese access to their artificial islands in the South China Sea, China’s nuclear policy may be changing soon.
Peoples Liberation Army Rocket Forces Insignia:
Spain’s nuclear safety regulator has given conditional approval for the restart and continued operation of the Garoña nuclear power plant, which has been offline for the past four years. Operator Nuclenor would be required to make a number of safety upgrades. world-nuclear-news.org
The nuclear industry’s top lobbyist told Wall Street analysts Thursday that the industry has reached a “tipping point” in gaining Washington’s attention to keep nuclear power plants from closing. washingtonexaminer.com
I have blogged about the Yucca Mountain Geological Repository before. The federal government decided to build a geological repository for spent nuclear fuel in an old salt mine under Yucca Mountain in Nevada. The project was formally approved in 2002. Preliminary work was done and millions of dollars were spent but the project was abandoned in 2011 by order of the Obama Administration. Meanwhile, spent fuel rods are filling up the cooling pools at nuclear reactors across the country. It is estimated that there will be no national repository before 2050. With the election of Donald Trump to the Presidency, some Republicans officials are calling for restarting the Yucca Mountain project.
A geophysicist named James Conca who is critical of the Yucca Mountain projects says that it was a poor choice for a repository because “the highly-fractured, variably-saturated, dual-porosity Yucca Mt. volcanic tuff with highly oxidizing groundwater was the wrong rock to begin with, causing the cost to skyrocket and the technical hurdles to keep mounting.” He also questions the need for such a repository at all. He said, “The problem this time is that most of our high-level nuclear waste is no longer high level. And most scientists agree we shouldn’t dispose of spent nuclear fuel until we reuse it in our new reactors that are designed to burn it.”
There are four kinds of nuclear waste in terms of levels of radioactivity. The least radioactive waste is called low-level waste (LLW) and there are six sites around the U.S. that are available for disposal of that type. The next level is referred to as transuranic waste (TRU). The Waste Isolation Pilot Plant in New Mexico is the national repository for that type. Then there is high level waste (HLW) which has no repository. The most radioactive of the types of wastes is spent nuclear fuel which also has no repository.
Conca points out that a great deal of the waste stored at Hanford in underground tanks used to be HLW but over the decades, radioactive decay has reduced it to TRU. That means that it could be safely stored at the WIPP along with other HLW. So there is no need to develop a new repository for that waste.
With respect to spent nuclear fuel, there are processes available which can extract useful radioactive materials including plutonium from spent nuclear fuel that can then be used to make fuel which can be burned in some modern nuclear power reactors. Conca says that it makes no sense to go to the trouble of mining and refining uranium for nuclear fuel when spent nuclear fuel can be reprocessed and burned in reactors. He says that if facilities are built to reprocess spent nuclear fuel, then it will be unnecessary for the U.S. to take the time, money and effort to build a new permanent national geological repository for spent nuclear fuel.
Critics of reprocessing proposals point to expensive failures in attempts to establish reprocessing facilities over the years both here and abroad. And the are major questions about the ultimate cost of such reprocessing which might require government support. Non-nuclear weapons proliferation activists point to the fact that reprocessing facilities could create weapons-grade plutonium from spent nuclear fuel.
The AA Bochvar Research Institute of Inorganic Materials (VNIINM) has announced further progress in Russia’s endeavour to close the nuclear fuel cycle. A subsidiary of nuclear fuel manufacturer TVEL, VNIINM said yesterday it had completed three state-sponsored contracts for the ‘Proryv‘, or Breakthrough, project. world-nuclear-news.org
Molten salt reactors are being discussed as an alternative to the popular pressurized water reactors. Although they have been studied since the 1950s, there has been little development work compared to pressurized water reactors. In a molten salt reactor, liquefied fluoride salts are used as a coolant. Sometimes the uranium fuel is mixed with the coolant.
Molten salt reactors run at higher temperatures for greater efficiency but lower pressures than water cooled reactors. They have passive safety systems that drain out the fuel and coolant if the temperature gets too high. They don’t leak radioactive steam. Their wastes are not as radioactive and have shorter half-lives that current water cooled reactors. Molten salt reactors can quickly respond to load changes.
Among the disadvantages of molten salt reactors is the fact that they need to have onsite chemical plants to manage the mixture of salts and to remove fission products. They will require major regulatory design changes for radically different designs. The nickel alloys that hold the molten salt are embrittled by the neutron flux. There is a greater risk of corrosion than in water cooled reactors. Molten salt reactors can be used as breeder reactors to make weapons-grade nuclear material. Some molten salt reactors use fuels that are almost as enriched as weapons grade materials which would be prohibited by current regulations. Neutron bombardment damages graphite moderators.
Researchers at the molten salt reactor and thorium research and develop program at the Shanghai Institute of Applied Physics (Sinap) have formed a partnership with the Australian Nuclear Science and Technology Organization (Ansto) to develop new materials for use in molten salt reactors.
Sinap created a series of samples of nickel (Ni) molybdenum (Mo) alloys that contained different percentages of silicon carbide (SiC) particles which were then taken to Ansto to be characterized. An Ansto representative said, “Structural materials for molten salt reactors must demonstrate strength at high temperatures, be radiation resistant and also withstand corrosion” when explaining the purpose of their research program.
The new NiMO-SiC alloys “possess superior mechanical properties owing to the precipitation, dispersion and solid-solution strengthening of the NiMo matrix”. Silicon Carbide particles had been considered for use in such alloys but they had a problem with dislocation at high temperatures. In the new alloys, nickel silicide nano-particle fill the holes between the silicon carbide particles in the matrix. A new powder metallurgy process was used to insure uniform distribution of particles in the alloys. Such dispersion is not possible with standard metallurgical techniques.
“The strength of these alloys stems therefore from the combination of dispersion strengthening by silicon carbide particles, precipitation strengthening by nickel silicide and solid-solution strengthening by molybdenum,” the Ansto representative said. “As well as superior high-temperature strength, these newly developed alloys have superior corrosion resistance and radiation damage resistance. The nano-particles present in the microstructure not only provide the obstacles for dislocation motion, but also provide sites/traps for radiation damage effects,” he added.
The creation of this new alloy should contribute significantly to the development of molten salt reactors.
