ML19350E537
| ML19350E537 | |
| Person / Time | |
|---|---|
| Site: | Indian Point, Sequoyah, Zion  |
| Issue date: | 05/27/1981 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | Advisory Committee on Reactor Safeguards |
| References | |
| 810528, ACRS-1840, NUDOCS 8106230244 | |
| Download: ML19350E537 (4) | |
Text
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g nas-an CLASS'9 ACCIDENTS SUBCOMMITTEE DATE ISSUED:
4 MARCH 24, 1981 EY 2 8 Igg g(q)9 g
WASHINGTON, D.C.
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The ACRS Subcommittee on Class 9 Accidents met in Washington, D.C. on March 24, 1981.
The purpose was to:
(1) discuss activities of the degraded core cooling steering group; (2) review infomation on hydrogen dueloped since the Sequoyah review that is pertinent to McGuire; and (3) discuss tne Staff's study of core melt mitigation features for Zion and Indian Point.
Principal Attendees W. Kerr, Chairman G. Arlotto, OSD W. Mathis, ACRS Member G. Sege, OPE g
J. Ray, ACRS Member D. Muller, NRR I
H. Etherington, ACRS Member C. Roberts, OSD wJL D. Ward, ACRS Member L. Soffer, NRR 2
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M. Bender, ACRS Member R. Blond, DSRR k;E
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S. Siegel, ACRS Consultant J. Meyer, NRR Ms.
(h M. Sichel, ACRS Consultant
- b. Ross, NRR
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J. Norberg, OSD No oral or written statements were received from members of the public.
Attached is the presentation schedule for the meeting.
Degraded Core Cooling Steering Committee Activities G. Arlotto (OSD) summarized progress by the Degraded Core Cooling Steering Committee.
Concerning the accident source term, a revision to 10 CFR 100 was said to be in order.
The new rule, however, must be formulated with care. The Steering Committee may recommend that a rule for Minimum Engineered Safety features not be formulated at this time.
The Steering Committee will l
recommend that operator qualifications and training r,c e addressed through rulemaking.
However, recommendations will be made to tue ED0 on t:his topic.
Mr. Bender inquired whether the Steering Committee will recommend that some requirements be made less severe, for example, the assumption of an instanta-neous large break LOCA. Mr. Arlotto said, "No."
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Class 9 Accidents March 24,1981 Safety Goal Development Committee Activitie:
G. Sege (OPE) described progress toward. formulation of a safety goal. A Commission statement on the subject will be published within a few days in the Federal Register, along with a request for comments.
A workshop on formula-tion of a safety goal will be held April 3, in Palo Alto, California, with a second workshop to be held in early summer.
A paper will be issued in late summer with Commission action by the end of 1981.
It has not been determined whether the safety goal will be promulgated as a proposed rule or whether the NRC will request Congressional legi sl ation.
Mr. Etherington inquired about the extent to which other countries utilize safety goals.
Mr. Sege did not know; he was not familiar with the Canvey Island work.
Comments Received on the Advance Notice of Rulemaking D. Muller (NRR) summarized comments received on the Advance Notice of Rule-making (ANR).
Most comments. favored form!11ation of a safety goal prior to rulemaking on Minimum Engineered Safety Features and Degraded Core Cooling.
The Staff, however, intends to proceed with both on the same schedule. The Staff intends to consider the risk of miclear relative to other forms of electricity generation.
Dr. Kerr inquired as to what action the Staff would take on siting policy if nuclear power was deemed safer than alternative means of generation, even under past siting policy.
The answer was that it would not affect the new siting rule.
Mr. Bender asked how the question of source term is factored into siting policy.
The reply was that an upper limit was taken on fission product release and a lower limit was taken on containment capability.
Siting Rulemaking C. Roberts (OSD) and L. Sofer (NRR) discussed siting rulemaking..Considera-tion is being given to distance from capable faults, distance from hazardous facilities (e.g. LNG), proximity of dams, and ground water characteristics.
Sixty comments were received on the Siting ANR.
A siting rule has been drafted.
It does not allow credit for ESFs, except possibly for extra-ordinary features.
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Class 9 Accid:nts March 24,1981
-9 The rule assumes five release categories, the most severe of which is assumed to occur for 10% of the core melts and is assumed to result in the following releases: 100% noble gases; 50% iodine; and 2/3 cesium & tellurium.
The release estimates were obtained using MARCH / CORRAL.
Dr. Kerr indicated that it is distrubing to see NRC using MARCH / CORRAL for decision-making purposes. Dr. Kerr added that there should be an estimate of the degree of uncertainty for the releases.
The rule includes the following demographic criteria:
Distance from plant, miles Northeast, Mideast US Elsewhere 2
2 0-2 500/mi 250/mi 2
2 2-30 750/mi 500/mi The reason the population density limit is higher for the Northeast / Mideast US is that the existing population density is higher than for the rest of the country.
The rule does not deal with changes in population density after the plant is built.
The rule does not consider site-Epecific meteorology.
Degraded Core Cooling Rulemaking R.
Blond (DSRR) indicated that topics to be considered for degraded core cooling rul emaking are:
containment heat removal; containment volume and design pressure; hydrogen; core catcher; residual heat removal; and vented-filtered containments.
Zion / Indian Point Mitigation Feature Study J. Meyer (NRR) summarized the NRC's study of core melt mitigation features for Zion / Indian Point (Z/IP).
It was noted that the ASLB may require Z/IP to install mitigation features regardless of what the ongoing probabilistic risk analyses conclude.
The Z/IP mitigation feature study utilized MARCrl/
CORRAL.
The goal was to find the lowest cost method that would result in an order-of-magnitude reduction in risk, assuming core melt as a starting l
point. The cost of such a system was estimated as $50M, exclusive of down 9 *
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Class 9 Accidents - March 24,1981 1
'o time. A 500-page report has been drafted and will be issued April 20, 1981.
j D..Ross (NRR) requested an ACRS meeting around the end of May to discuss the report.
Consideration of Hydrogen at McGuire D.
Ross discussed the ASLB's consideration of hydrogen at McGuire, in the course of _ one mcnth of hearings.
Sandia is still taking the position that ignitors should not be placed at the ice condenser outlet.
4 Interim Rule for Degraded Cores J. Norberg -(OSD) discussed the proposed interim rule on degraded cores. The rule requires inerting BWR Mark I and II; hydrogen control systems to cope with 75% equivalent clad reaction on BWR Mark IIIs and ice condensers; and analyses for other containments.
The rule also requires: (1) operator train-ing to detect and mitigate degraded core - acc' dents; (2) accident monitoring instrumentation; and (3) saxpling capability during an accident.
Comments received on the rule included: (1) design studies for hydrogen mitigation for large PWR containments are not ' worthwhile; (2) many of the dates set for installing instruments and equipment cannot be met; and (3) some parts of the rule do not allow enough flexibility.
Future Meetings No further meetings are currently scheduled.
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