Researchers find that small modular nuclear reactors can generate higher volumes and greater complexity of radioactive waste because they are inherently less efficient. The first wave of mini nuclear power plants can generate more radioactive waste than conventional large-scale ones while generating the same amount of power. Small power plants made a lot of noise. However, this information is sure to bring more than that, we think. Because the amount of waste is really boring.
Small modular reactors (SMRs), a cheaper and faster way to build new nuclear power capacity, have been discussed earlier by their developers and supporters. British prime minister Boris Johnson has claimed that they can produce electricity by 2030.
What is Uranium Enrichment? How to Dispose of Uranium as Waste?
Uranium is a metal that can be found in rocks all over the world. Uranium has several naturally occurring isotopes, which are forms of an element that differ in mass and physical properties but have the same chemical properties. Uranium has two primordial isotopes: uranium-238 and uranium-235. Uranium-238 makes up the majority of uranium on Earth but cannot produce a fission chain reaction, while uranium-235 can be used to generate energy through fission, but it makes up less than 1 percent of the world's uranium.
To increase the probability of natural uranium fission, it is necessary to increase the amount of uranium-235 in a given sample through a process called uranium enrichment. Once uranium is enriched, it can be effectively used as nuclear fuel in power plants for three to five years, after which it is still radioactive and must be disposed of in accordance with strict rules to protect people and the environment. Spent fuel, also called spent fuel, can also be converted into other types of fuel for use as new fuel in private nuclear power plants.
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The US government also provided financial support to NuScale Power to develop its own version of the technology.
But to date, there has been little independent assessment of how the radioactive waste produced by SMRs compares to large-scale ones.
Lindsay Krall of Stanford University in California and colleagues used data that NuScale Power shared publicly with US officials to evaluate the technology. As a result, he made predictions to model from three different SMR technologies.
They compared SMR technology to a conventional 1.1 gigawatt nuclear reactor, which is about a third of the capacity of a new nuclear power plant built in southwest England.
They found that SMRs can increase the volume of short-lived low- and intermediate-level waste (the two lowest of the three categories) by up to 35 times compared to a large conventional reactor when looking at the waste generated per unit of electricity generated.
For long-lived equivalent waste, SMRs will produce up to 30 times more and for spent nuclear fuel up to 5 times more. The variation in these numbers reflects the variation expected in SMR designs currently in development.
“The information currently being revealed by reactor developers can be viewed for demonstration purposes,” Krall says.
“SMR performed worse on nearly all our measurements compared to standard commercial reactors”
These measurements included the heat from radioactive decay and the radiochemistry of the spent fuel.
The study shows that because SMRs are inherently less efficient, they generate higher volumes and greater waste complexity.
Nuclear power generation involves a nuclear chain reaction in which a single nuclear reaction in the reactor core creates neutrons which then on average cause one or more subsequent nuclear reactions.
However, according to Krall's team, SMRs leak more neutrons from their cores than a larger reactor, meaning they cannot maintain the self-sustaining reaction for long.
Krall says that even a small difference in neutron leakage has a significant impact on the composition of the waste.
Diane Hughes of NuScale Power says the study is based on old knowledge and the wastage per unit of energy compares favorably with large reactors.
“We disagree with the conclusion that the NuScale design creates more spent fuel per unit of energy than currently operating light water reactors,” he says.
The UK government has funded Rolls-Royce SMR to advance its own version of the technology.
This design was not considered in the latest analysis, but a Rolls-Royce SMR spokesperson said the business will present waste volume estimates as part of its years-long journey through the UK's nuclear regulatory approval process, which began in April.
According to the spokesperson, the Rolls-Royce SMR design “includes several technical advances that minimize waste generation.”
With the exception of Finland and Sweden, a few countries have made progress on plans for long-term facilities to store their nuclear waste underground.
“We need to get more serious about managing [SMRs'] nuclear waste in a practical way,” Krall says.