Before proceeding forwarded, I encourage the reader to view the following short videos on NuScale Power's design for a small modular reactor (SMR) so that you may have a foundation on which to build an understanding of what will be discussed in this blog entry:
I dislike criticizing those trying hard to provide the next generation of passively safe nuclear power plants, and this blog post should NOT be misconstrued as such. Efforts by Westinghouse with its AP1000, Areva with its EPR, GE-Hiatchi with its ABWR, ESBWR and PRISM, KEPCO with its APR1400, Mitsubishi with its APWR and of course NuScale with its SMR are being made:
- In a hostile regulatory environment
- Against the concerted opposition of anti-nuclear eco-wackism, and
- In the midst of a scientifically illiterate populace for whose benefit such power generation is being designed and developed.
Furthermore, of all the forms of electrical power generation, nuclear energy has the LOWEST mortality rate. See Next Big Energy Future: Update of Death per Terawatt Hour by Energy Source. But nevertheless, we have to look at the facts dispassionately regardless of our prejudices.
Rod Adams of Atomic Insights has written an article at Forbes Magazine entitled NuScale Readiness For Design Certification Submission.
ASIDE: Having openly advocated for gargantuan government programs like Obamacare, Adams in his article now decries the excessive regulation of government, at least when it comes to his pet cause, nuclear energy. He rightly complains about the monumental cost of reviewing an applicant's documentation regarding nuclear safety. He correctly points out "...the way that the monopoly provider of regulatory services in the United States functions," but ironically has no difficulty with government monopolization of health care. Perhaps Adams ought to concern himself with the nuclear safety issues at hand. END ASIDE
Here is the US NRC's Summary of Observations Related to a Staff Preapplication Readiness Assessment of a Potential NuScale Power, LLC Design Certification Application. One of the issues mentioned in this letter is this:
There was insufficient technical information regarding Appendix A, ‘General Design Criteria (GDC),” to 10 CFR Part 50, GDC 27, “Combined reactivity control systems capability.” There were multiple statements regarding the ability of the design to achieve and maintain safe shutdown in various sections of the draft DCA that conflicted with Section 15.0.4, “Evaluation of a Return to Power.” Additionally, Section 4.3.1.5 of the draft DCA described two differing analytical assumptions: one involving achieving initial shutdown with the highest worth control rod assembly (CRA) assumed to be stuck out of the core, and the other involving maintaining long-term shutdown through insertion of all CRAs and a postulated return to power.
GDC 27 in Appendix A of 10 CFR 50 states:
Criterion 27—Combined reactivity control systems capability. The reactivity control systems shall be designed to have a combined capability, in conjunction with poison addition by the emergency core cooling system, of reliably controlling reactivity changes to assure that under postulated accident conditions and with appropriate margin for stuck rods the capability to cool the core is maintained.
Concerning this the US NRC had issued a previously letter entitled: Response to NuScale Gap Analysis Summary Report for Reactor Systems Reactivity Control Systems, Addressing Gap 11, General Design Criterion 27 (PROJ 0769). This letter states in part:
...The NRC staff understands that in some cases NuScale believes that regulations are not applicable to NuScale based on the design as described in the Report. In addition, other NRC regulations by their terms may or may not apply to the NuScale design. For example, a regulation that applies only to boiling water reactors would not apply to the NuScale design, which is a pressurized water reactor. In general, a regulation that requires, for example, a certain function or design attribute will apply to the NuScale design. The mere fact that the NuScale design employs a novel means to perform a required function or include a required design attribute does not necessarily trigger a need for an exemption, nor is the novel means for compliance a reason why the regulation would not apply....
...Based on the staff’s current understanding of the NuScale design, the NuScale design would not appear to meet the GDC 27 requirement of “reliably controlling reactivity changes to assure that under postulated accident conditions, and with appropriate margin for stuck rods, the capability to cool the core is maintained.” The staff acknowledges that currently licensed pressurized water reactors (PWR) would not remain subcritical in the short term (i.e., within about the first few minutes of accident initiation) for some accident scenarios (e.g., main steam line break). Nonetheless, beyond the short term, all PWRs remain subcritical indefinitely, and the NRC has not licensed a power reactor that did not remain subcritical beyond the short term following an accident through the use of safety related structures, systems and components (SSC). GDC 27 allows credit for boron addition from the ECCS, and PWRs maintain subcriticality indefinitely beyond the short term by taking credit for such boron addition. In regard to system safety class, the reactivity control systems function together with the heat removal systems to perform the functions described in the 10 CFR 50.2 definition of safety-related SSCs and, therefore, those reactivity control and cooling systems are safety related....
...In view of the foregoing, the staff’s current view is that GDC 27 requires that the reactor be reliably controlled and that the reactor achieve and maintain a safe, stable condition, including subcriticality beyond the short term, using only safety related equipment following a postulated accident with margin for stuck rods. Both current, approved PWRs, using safety related control rods and safety-related soluble boron addition, and boiling water reactors (BWR), using safety related control rods, reliably control reactivity and achieve a safe, stable condition with appropriate margin for stuck rods....
...Because the currently available information indicates that the NuScale design does not ensure that the reactor would remain subcritical beyond the short term, it would appear that NuScale would need to request an exemption from GDC 27, with respect to re-criticality. The staff has also concluded that consideration of such an exemption entails policy issues under the purview of the Commission and that such an exemption would warrant Commission consideration and direction prior to the staff supporting the exemption. The staff will proceed and engage the Commission on the policy issues; however, the staff does not believe these policy issues will likely be resolved prior to the anticipated submittal date for the application....
The definition of safety related system structure or component is given in 10 CFR 50.2:
Safety-related structures, systems and components means those structures, systems and components that are relied upon to remain functional during and following design basis events to assure:
(1) The integrity of the reactor coolant pressure boundary
(2) The capability to shut down the reactor and maintain it in a safe shutdown condition; or
(3) The capability to prevent or mitigate the consequences of accidents which could result in potential offsite exposures comparable to the applicable guideline exposures set forth in § 50.34(a)(1) or § 100.11 of this chapter, as applicable.
We all wish NuScale well in its endeavors to license a passively safe small modular reactor. Yes, the NuScale design is practically sailor-proof. It is an integral reactor vessel within which are the steam generators and pressurizer, and that vessel is within an evacuated containment vessel, which in turn is placed in a massive pool of borated water. If anything really bad happens, then eventually the core will be doused with borated water from this huge pool. The water will keep the core cool and the boron will shut it down and keep it shut down. However, NuScale is going to have reconcile all these things about GDC 27 to the NRC's satisfaction. Regardless that the regulatory atmosphere is hostile, the NRC holds the keys of getting this new design licensed. Smarter minds than what is at the NRC will therefore have to justify to the NRC why for a very unlikely scenario it is acceptable to allow re-criticality after a hypothetical event however improbable it may be, and however transitory that re-criticality may be since boron from that huge pool will eventually result in complete shutdown. Nuclear regulation is NOT subject to a democratic vote, and the United States is NOT a Democracy (two wolves and one sheep voting on what's for dinner), but a Republic where rule of Law is sacrosanct. Law and its subsidiary regulation are designed to protect public health and safety, and to provide for the common defense. If law or regulation fail to do that, then the right solution is NOT defiance (i.e., I get to interpret the regulation as I see fit), but change from within and through the system. And if I can't explain why my idea is safer than the Regulator's idea, then maybe it isn't safer after all. Humility - right thinking about one's self and one's place - is the touchstone of all the other virtues.
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