ML19309H847

Forwards for Info ACRS Re Review of Proposed Core Ladle Design for Floating Nuclear Plants 1-8

ML19309H847
Person / Time
Site:	Atlantic Nuclear Power Plant
Issue date:	04/25/1980
From:	Baer R Office of Nuclear Reactor Regulation
To:	Collier A OFFSHORE POWER SYSTEMS (SUBS. OF WESTINGHOUSE ELECTRI
References
NUDOCS 8005200192
Download: ML19309H847 (1)

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i April 25,1980 Docket No. STN 50-437 Mr. A. R. Collier President Offshore Power Systems P. O. Box 8000 8000 Arlington Expressway Jacksonville, Florida 32211

SUBJECT:

ACRS LETTER - CORE LADLE DESIGN (Floating Nuclear Plants 1-8)

Enclosed for your information is a copy of a letter, dated April 16, 1980, from the Advisory Committee on Reactor Safeguards concerning its review of the proposed core ladle design for your Floating Nuclear Plants 1-8.

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Robert L. Baer, Chief Light Water Reactors Branch No. 2 Division of Project Management

Enclosure:

As Stated ccs w/ enclosure:

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.ADVtsORY COMMtTTEE ON REACTOR SAFEGUARDS

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!ir. William J. Dircks, Acting Executive Director for Operations U. S. fiuclear Regulatory Commission 1lashington, D. C.

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SUBJECT:

FLOATING NUCLEAR PLANT (FNP) CORE LAOLE Ocar Mr. Dircks:

During its 240th meeting, April 10-12,'1980, the Advisory Committe'e on Reactor Safeguards (ACRS) completed its review of Offshore Power Systems' (0PS) proposed core ladle design for the Floating Nuclear Plant (Topical Report No. 36A59).

This Topical Report was also discussed at Subcommittee meetings on June 27, 1979 and Nove=bar 17, 1979.

During its review the Committee had the benefit of presentations by representatives of the NRC Staff and OPS.

OPS has agreed to the NRC Staff requirement to replace a previously pro-posed concrete pad below the reactor vessel with a magnesium oxide (Mg0) ladle in order to satisfy the Floating Nuclear Plant (FNP) Final Environ-mental Statement, Part III.

This statement requires that Mg0 or other equivalent refractory material be used to provide resistance to a core melt-through and to provide additional delay time so that interdictive measures can be taken.

The NRC Staff has required a minimum delay time of two days for melt-through of the ladle and has required that the proposed refractory material and ladie design not compromise safety.

OPS must obtain NRC approval of the final ladle design and the refractory material selected prior to construction of the major elements of the FNP hull structure.

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ladle design approval and material selection is not expected until after a detailed R&D program by OPS and safety research by the NRC Staff are com-pleted.

Representatives of the NRC Staff have informed the ACRS that they have not found any disadvantages from the installation of the proposed MgG ladle. The ACRS was told that the proposed MgG ladle would significantly mitigate the temperature and pressure transients in the containment following a core melt accident and that it would significantly mitigate the amoeat of radioactive material sparged from the dobris into the atmosphere of the upper contain-ment.

This would tend to reduce the airborne release.

!!r. William J. Dircks April 16,1980-Discussions have indicated, however, that there are still areas that need to be furth'er developed to fully understand the heat transfer character-istics of the ladle, reactor vessel, and the surrounding structures.

In addition, the Committee believes that further study is needed relative to the probability of,and consequences if water should gain access to the ladle either before or after the molten core reaches it.

For this and other reasons, it must be confirmed that the presently proposed design with the use of refractory material in the cavity, which would del. a core melt-through to the sea, does not, in fact, increase the risk to the public via the air pathway if the containment were to rupture due to overpressure.

The NRC 'taff criterion requiring a minimum molten core holdup time of two days was aeveloped prior to the recent Staff position as enunciated in the NRC Siting Policy Task Force report (NUREG-0625).

This position specifies that, for land-based plants, 10 CFR Part 100 would be changed to r ; quire reasonable assur;nce that interdictive measures would be possible to limit groundwater contamination resulting from Class 9 accidents.

The C, how-

ever, has not yet developed a specific approach with regard tc possible icplementation of this recommendation for land-based plants.

As a result, it is difficult to ascertain whether, during the next few years, this recommen-r dation is likely to lead to a significant alteration in the NRC's basis for its criterion for the FNP core ladle.

If it does, this could necessitate a ma,iar chanc2 in the criterion itself.

Since tne FNP uses an ice-condenser containment, the containment building has a low design pressure and a relatively small volume.

This makes it more vulnerable to certain postulated accidents which involve the rapid combustion of released hydrogen or other phenomena which could cause the buildup of a large overpressure in the containment.

The FNP may be able to take advantage of the presence of the ocean to serve as a filter for containment venting for some accident scenarios.

However, an overall approach to coping with acci,

dents beyond the current design basis for new ice-condenser plants has not been. developed by the NRC or proposed by OPS.

The Committee recommends that the NRC and OPS give priority to resolving this matter.

It should not be left to a rulemaking procedure to be completed some time after issuance of a manufacturing license.

The Staff has not provided an opinion on what constitutes an acceptable frequency, with some confidence level, for an accident in which a molten core eventually reaches the ocean.

The Committee suggests that an effort to establish such criteria could be worthwhile; however, it should not be manda-tory for completion of the FNP review for a manufacturing license.

The Cominittee also urges the NRC Staff to continue to work toward the establish-ment of criteria for limiting accidental liquid releases from nuclear power plants, in general.

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Mr. William'J. Dircks April.16, 1980.

The Committee believes the conceptual design presented by OPS can, with careful attention to thermal analysis and material properties, be developed to a system that has a reasonable probability of accomplishing its design purpose.

To support such analyses, the Committee recommends that the NP.C Staff engage the services of consultants expert in the design of high-temper-ature melting furnaces and the handling of high-temperature molten materials.

The Committee agrees that the proposed FNP core ladle design is adequate for the FNP manufacturing license; however, the planned tests and analytical programs must confirm present estimates of the operation of the ladle before th FNP is built and operated.

Sincerely,

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d Milton S. Plesset Chairman 9

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9 Mr. A. R. Collier President Offshore Power Systems P. O. Box 8000 8000 Arlington Expressway Jacksonville, Florida 32211 cc:

Vincent W. Campbell, Esq.

Vice President & General Counsel Offshore Power Systems P. O. Box 8000 8000 Arlington Expressway Jacksonville, Florida 32211 Thomas M. Daugherty, Esq.

',r Offshore Power Systen.

P. O. Box 8000 8000 Arlington Expressway Jacksonville, Florida 32211 Barton Z. Cowan, Esq.

Eckert, Seamans, Cherin & Mellott 600 Grant Street, 42nd Floor Pittsburgh, Pennsylvania 15219 David S. Fleischaker Natural Resources Defense Council 91715th Street, N. W.

Washington, D. C.

20005 Dr. Glenn L. Paulson Assistant Comissioner State of New Jersey Department of Environmental Protection Labor and Industry Building

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John Fitch Plaza Trenton, New Jersey 08625 r-Keith A. Onsdorff, Esq.

Miriam N. Span, Esq.

Assistant Deputy Public Advocates 520 East State Street Post Office Box 141 Trenton, New Jersey 08625 Richard M. Hluchan New Jersey State Deputy Attorney General State House Annex Trenton, New Jersey 08625

Mr. A. R. Collier

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cc: Carl Valore, Jr., Esq.

Valore, McAllister, DeBrier, Aron & Westmoreland Mainlar.d Professional Plaza 535 Tilton Road P. O. Box 152 Northfield, New Jersey 08225 Mr. Harold P. Abrams 9100 Amherst Avenue Margate, New Jersey 08402 Dr. Willard W. Rosenberg 8 North Rumson Avenue Margate, New Jersey 08402 Mr. John Williamson 211 Forest Drive Linwood, New Jersey 08221 d.

Harold P. Green, Esq.

Fried, Frank, Harris, Shriver and Kampelman Suite 1000, The Watergate 600 600 New Hampshire Avenue, N. W.

Washington, D. C.

20037 Nuclear Coordinator Office of Merchant Marine Safety Commandant (GFriT-4)

U. S. Coast Guard

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Washington, D. C.

20590 71%...

G.'I' Mr. Mitchell Attalla

,e 4028 Ponce DeLeon Avenue Jacksonville, Florida 32217 Mr. Reg Crowder Jacksonville Journal P. O. Box 1949 Jacksonville, Florida 32201

' Sheldon J. Wolfe, Esq., Chairman y.-

Atomic Safety and Licensing Board

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U. S. Nuclear Regulatory Commission Washington, D. C.

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Dr. David R. Schink Departrent of Oceanography Texas A. & M. University l

College Station, Texas 77840 s

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Mr. A. R. Collier

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cc: Mr. Glenn 0. Bright Atomic Safety and Licensing Board U. S. Nulear Regulatory Comission

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Washington, D. C.

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Richard' S. Salzman, Esq., Chairman Atomic Safety and Licensing Appeal Board U. S. fluclear Regulatory Commission Washington, D. C.

20555 Dr. John H. Buck Atomic Safety and Licensing Appeal Board

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Washington, D. C.

20555 Mr. Michael C. Farrar Atomic Safety and Licensing Appeal Board U. S. fluclear Regulatory Commission j

Washington, D. C.

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