NuScale nuclear claims that the old rules for calculating embrittlement of nuclear reactor pressure vessels are outdated and they want to replace them with new rules. They say that the old rules are too conservative, and they want to relax the rules. However, the original rules were based on basic science. Furthermore, NuScale reactor pressure vessels are apparently more at risk than regular nuclear reactors for sudden catastrophic pressure vessel failure, and thus catastrophic nuclear disaster. According to a study commissioned by the US DOE, NuScale, and similar designs, have thinner nuclear reactor pressure vessel shells, but “significant radiation damage occurs through a greater fraction of wall thickness“. Thus, they suffer from more embrittlement and therefore would be more subject to sudden through wall cracking and pressure vessel failure. And, yet, Thomas A. Bergman, on behalf of NuScale Power, LLC “requests that the NRC amend 10 CFR part 50 to alleviate a requirement for calculating the embrittlement for advanced reactor designs and add the embrittlement trend curve formula for calculating the mean value of the transition temperature shift described in American Society for Testing and Materials (ASTM) E900-15…” https://www.regulations.gov/document?D=NRC-2019-0180-0003 The earlier examples are of differing designs from NuScale. A mean value is the arithmetic average and doesn’t take into consideration scatter. If you add Bill Gates’ wealth with your own, and divide by two, it probably doesn’t reflect your wealth. That’s an arithmetic average. In many cases we want the median average – half above and half below. However, when it comes to nuclear disaster, we want the value which is the most safe and conservative. The safest, of course, is no more nuclear reactors. They are unnecessary and the risks are too high.
Mining Awareness 18th Dec 2019 read more »
Nuclear industry hopes of one day bringing small, factory-built nuclear power plants to communities and industrial sites have cleared a first regulatory hurdle with the Trump administration, over objections from the Federal Emergency Management Agency and others that regulators are cutting corners on safety and disaster planning. The Nuclear Regulatory Commission approved a preliminary site permit this week sought by the Tennessee Valley Authority, the nation’s largest public utility, for a so-called small modular reactor near Oak Ridge, Tennessee. It´s the first such permit in the country. Moving ahead on any such project would require a string of other regulator sign-offs, putting installation and opening of one of the less-chunky nuclear plants years away at the earliest.
Daily Mail 19th Dec 2019 read more »
The US Nuclear Regulatory Commission (NRC) is seeking public comment on proposals to apply risk-based emergency preparedness requirements to small modular reactors (SMRs) and other new technologies. The proposed rule would include a scalable approach for determining the size of the emergency planning zone around such facilities.
World Nuclear News 19th Dec 2019 read more »