ML20198S600

Statement of Jk Asselstine Before Committee on Energy & Commerce,Subcommittee on Energy Conservation & Power Re Impact of Chernobyl Accident

ML20198S600
Person / Time
Site:	Pilgrim
Issue date:	05/22/1986
From:	Asselstine J NRC COMMISSION (OCM)
To:
References
CON-#487-5032 2.206, NUDOCS 8606100493
Download: ML20198S600 (5)

Text

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PDil Statement of Comissioner James K. Asselstine U.S. Nuclear Regulatory Comission before the Subcomittee on Energy Conservation and Power r Comittee on Energy and Comerce May 22, 1986 Mr. Chairman, I disagree in many respects with the Comission's testimony on the impact of the Chernobyl accident. Now that the Chernobyl accident has turned the spotlight onto the safety of the U.S. nuclear power 4

reactors, the Comission would have the Congress and the public believe that the U.S. plants may be five times safer than estimated just a few l

months ago, that the U.S. plants are far safer than the Comission's provisional safety goals, that the U.S. plants are much safer than believed when the Commission deemed the severe accident risks to be acceptable last year, and that the consequences of a core meltdown in the U.S. are "very different" than the consequences of a core meltdown in the Soviet Union.

Indeed, the Commission now seems to believe that the TMI inspired backfits, which many argued before Chernobyl to have questionable if not negative impacts on safety, have turned out to be very positive contributors to j safety. Before Chernobyl, those " undisciplined" TMI backfits served as

! part of the basis for the promulgation of the Commission's backfit rule, which erects a substantial barrier against efforts to improve safety, t .

After Chernobyl, the Comission and the nuclear industry find that those TMI backfits have provided substantial improvements in safety. Finally, according to the Commission, apart from finding that the light water

, reactors in the U.S. cannot have large graphite fires, it is premature to l,

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. draw conclusions re-garding the ramifications of the Chernobyl accident for our nuclear power program, i

Mr. Chairman, by focusing on the design differences between the Soviet plants and U.S. plants, the Comission misses the broader lessons of the

.j Chernobyl accident for nuclear safety in the United States. Those broader i

lessons have to do with the acceptability of core meltdown accidents and l the adequacy of our current efforts to prevent such accidents and to minimize their consequences should one occur. I want to start with what I i

think are three inescapable conclusions regarding the risk of core meltdown '

j accidents in the United States.

I First, unless further steps are taken to reduce substantially the likeli-

! hood of a core meltdown accident, we can expect to see such an accident at i

' a U.S. plant within the next 20 years. This conclusion is supported by the probabilistic risk assessments done for U.S. plants to date, by the substantial uncertainties in those assessments, including their limited ability to account for human performance and external accident initiators, j and by recent operating experience with the plants which shows that at least some PRA assumptions are overly optimistic. As the Comission's f

chief safety officer noted recently, serious operating events illustrate

that in the real world, system and component reliabilities can degrade below those we and the industry routinely assume in estimating core melt I

j frequencies.

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a Second, as is apparently the case with the Soviet reactors, our reactors were not designed for large-scale core meltdown accidents. Because such accidents were assumed to be so unlikely as to be incredible, they were judged to be outside of the design basis for the plants. One consequence of this assumption is that U.S. reactor containments were designed to withstand the rupture of a large steam pipe but were not designed to withstand large-scale core meltdowns.

Third, although we believe that all of our reactors have some capability to withstand severe core meltdown accidents, the extent to which they can withstand such accidents depends upon the sequence of events during the accident, the individual plant designs and the manner in which each plant ,

is operated and maintained. While we hope that their occurrence is unlikely, there are accident sequences for U.S. plants that can lead to rupture or bypassing of the containment in U.S. reactors which would result in the off-site release of fission products comparable to or worse than the releases estimated by the NRC staff to have taken place during the Chernobyl accident. That is why the Commission told the Congress recently that it could not rule out a commercial nuclear power plant accident in the United States resulting in tens of billions of dollars in property losses and injuries to the public. The bottom line is that, given the present level of safety being achieved by the operating nuclear power plants in this country, we can expect to see a core meltdown accident within the next 20 years and it is possible that such an accident could result in off-site releases of radiation which are as large as, or larger than, the releases estimated to have occurred at Chernobyl.

My point is that 1.arge power reactors, in this country and abroad, are not inherently safe. Each design has its own core meltdown vulnerabilities.

If nothing else Chernobyl should remind all of us that core meltdown 1

accidents can happen and, even assuming evacuation is successful, that the resulting releases can leave large tracts of land and buildings highly contaminated.

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' To me, the lessons of Chernobyl are simple and straightforward. Given the uncertainties in containment and plant performance, the occurrence of a severe core meltdown accident over the next 20 years is unacceptable. That

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was the judgment of the President's Comission on the Three Mile Island Accident six years ago, and it is no less true today. We should return to .

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! the safety philosophy espoused by the Kemeny Commission at that time -- to pursue all practical measures both to prevent core meltdown accidents from occurring and to minimize their consequences should one occur. This safety philosophy is fundamentally at odds with the Comission's decision in the Indian Point Special Proceeding, with the Severe Accident Policy Statement, with the Comission's backfit rule and with the Comission's provisional safety goal. It is also at odds with the passion for deregulation that has i been sweeping the nuclear industry and the Comission over the past two years.

Many other countries have and are taking U.S.-developed technology and l

minimum safety standards, and building on them to have better nuclear I

plants with greater defense-in-depth than that being achieved in this country. These other countries have better designed plants that are i

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operated and maintained better than the U.S. plants and that are safer than the U.S. plants. They have achieved a far better state of affairs with respect to reliability and safety of their plants than this country has.

And, they have accomplished this in a disciplined manner at reasonable costs. While we are looking at foreign safety experience in the aftermath of the Chernobyl accident, we should consider following their example.

Thank you.

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