ML19316C435
| ML19316C435 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 11/05/2019 |
| From: | Pierce P - No Known Affiliation |
| To: | Spitzer R Atomic Safety and Licensing Board Panel |
| SECY/RAS | |
| References | |
| Download: ML19316C435 (4) | |
Text
{{#Wiki_filter:NOVEMBER 5, 2019 U.S. NUCLEAR REGULATORY COMMISSION ATOMIC SAFETY AND LICENSING BOARD RONALD M. SPITTER, CHAIR RE: SEABROOK NUCLEAR REACTOR ASR COMPROMISED CONCRETE SIR: ENCLOSED PLEASE FIND M.I.T TECHNOLOGY REVIEW ARTICLE FROM MAY 2019 RE THREE MILE ISLAND MELTDOWN. THE CONCRETE AT SEABROOK REACTOR HAS BEEN EXPOSED TO 30 YEARS OF RADIATION AT 40,000 CURIES PER YEAR WHICH IS 1.2 MILLION CURIES. NO CONCRETE COULD WITHSTAND SUCH CUMULATIVE EMISSION WITHOUT SOME PHYSICAL DETERIORATION. ASR DEGRADATION DUE TO SALT WATER EXPOSURE AND EXCESSIVE RADIATION IS PROGRESSIVE AND NOY REVERSIBLE. FAILURE IS TO BE EXPECTED WHETHER GROSS STRUCTURAL OR PARTIAL. WAffiNG FOR THAT EVENT IS A SAFETY RISK THAT IS NOT DEFENSIBLE. AS YOU READ THE ENCLOSED ARTICLE YOU WILL SEE THAT THE LOSS OF CORE COOLANT IS ONLY ONE ASPECT OF THE CRISIS. MY FEAR AT SEABROOK IS THE MAJOR LONG DISTANCES THE COOLING WATER MUST TRAVEL FROM THE OCEAN INTAKE ENCLOSED IN CONCRETE IN THE MARSHES. FAILURE DURING THE 1.5 MILLION GALLON COOLING PATH WOULD BE HARD TO DETECT OR REMEDY. G_,. *
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I,,'. I ! i I . 1 'I I I ,I ,I. :, 1, ~I. I ' 10 Predicting Three Mile Island i was still dark outside when the first thing went wrong. At 4 a.m. on March 28, 1979, a minor malfunction caused a relief valve to open on one of the nuclear reactor units at the Three Mile Island power plant. The valve got stuck and released cooling water from around the core, causing the reactor to auto-matically shut off. While that would not have posed any harm had the situation been properly managed, several instrument mal-functions meant that the workers running the plant had no way of knowing it had lost coolant. Amid the chaos of ringing alarms and flashing warning lights, the operators. took a series of actions that made condi-tions much worse, allowing the reactor core to partially melt down. The plant's containment systems prevented a serious release of radioactive material;but a small amount ofradioactive xenon, krypton, and iodine gas leaked into the atmosphere and about 140,000 people were forced to evacuate their homes. For many,' the widely publicized inci-dent was a wake-up call about the poten-tial dangers of nuclear power. Nci new plants were built for more than 30 years afterward.
- The disaster shook the industry to its core, but Norman Rasmussen, PhD '56, a professor in the Department of Nuclear Engineering at MIT, had warned four ye*ars earlier of the dariger of a very similar scenario. And as fate would have it, the meltdown he predicted happened just 13 miles from his hometown of Harrisburg,
- Pennsylvania.
In 1972, the US Atomic Energy Commission had hired Rasmussen, a father of two who had taught at MIT since finishing his PhD in 1956, to conduct cl: study on public risk from nuclear acci-dents in the United States. The paper, written by Rasmussen and a team of more than 40 experts, was the first probabilistic study of nuclear power. The Rea.ctor Safety Study-,-WASH-1400, often referred to simply as the Rasmussen Report-used probabilistic risk assessment techniques to predict the likelihood of various scenarios that might unfold at nuclear power plants. Prior stud-ies hiid used deterministic methods of risk assessment, which focused on the disaster outcomes of a given scenario instead of calculating their probabilities. Rasmussen's report pointed out that small-break loss-of-coolant accidents were a more probable threat than large-break ones. And in addi-tion to conducting a general assessment of pumps and valves, Rasmussen and his team argued that human reliability was a necessary factor to consider because if automatic systems malfunctioned, humans would have to intervene. This ran contrary to the prevailing notions about nuclear power safety man-agement. The physics community at the time largely assumed that the built-jn safety mechanisms on nuclear power plants were sufficient to safely handle any accident in a timely fashion-in other words, that technical back-ups. were more important than human actions. REC.EiVED NOV !1 -* LU l~ l::3oard of Sci<::ctmen Town of Rocl,port A controversial report, an MIT professor, and the most publicized nuclear disaster in US history By Eva Frederick, SM 'J.9 "The human role was largely ignored and, if considered at all, the operators were assumed to onlyundertake actions favorable to safety;' wrote Jan van Erp in an Argonne National Lab report on the TMI accident. Van Erp realized that the Rasmussen Report should have been a warning of disaster to come. But at the time it was published in 1975, the analysis met sub-stantial criticism and backlash-ironically, largely on grounds that it underplayed the risks. The American Physical Society said nuclear.,power posed far greater dangers than Rasmussen and his team predicted, . and the Union of Concerned Scientists published a 150-page critique of the paper.
- Subsequent review of the Rasmussen Report by what had by then become the Norman Rasmussen, PhD ' 56, cau-tioned against reJ.ying on auto-matic safety systems in nuclear power plants. UnfortunateJ.y, ope:cators at Three Mile Island (right) did just that.
Nuclear Regulatory Commission showed that Rasmussen did underestimate the uncertainties.in some situations. One reviewer calle.d the report "inscrutable:' So in January 1979, the NRC decided to withdraw its endorsement of the executive summary of Rasmussen's study. The night before the announcement Rasmussen got a c_all late in the evening about the NRC's plans. He later told his friend and colleague Michael Golay, another MIT professor, that he lay awake all night worrying. "He was truthfully upset, as you'd expect," Golay says. "He was about to be embarrassed nationally:' 'I\\vo months later, Three Mile Island melted down. The meltdown was caused by a small loss of coolant-not a large one, as other 1a6s*r reports.had envisioned.And, as Rasmussen had predictt!d, the incident was exacet-.. bated by a series of human errors. It turns out that Rasmussen and his colleagues were nearly spot-on about a couple of other things as well: Rasmussen prediFted the high probability of an acci-dent like Three Mile Island and also cor-rectly predicted that the health effects of such an accident would be negligible in their severity. "[Three Mile Island] was essentially a vindJcation of the report;' Golay says. Over the years following the disaster at Three Mile Island, people began to realize
- tl1e value of Rasmussen's study and its use
- of risk assessment in the context of nuclear power. By 1995, the NRC came out with a formal policy statement that recommended employing such analysis; n
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. Town o'i Rockpor.. "They basically backed away from their 1979 rejection [of the Rasmussen Report] and its methods and said, 'Use the meth-ods. They can help us do a better job."' Golay says. The risk assessment method that Rasmussen pioneered was used* more and . more frequently, and tod~y*it is one of the
- essential tools for evaluating nuclear safety all over th.e world. Rasmussen died in 2003,
- _having lived to see his report accepted by the riuciear physics community.
- "Rasmussen's strength was he was really good at integrating information from diverse sources into a consistent approach to a problem;' Golay says. ".It's amazing how that first report has stood the test of tirrie. People still cite it. It's hard to get it right to such a*degree on
- the first pass." *
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