ML20126D444
| ML20126D444 | |
| Person / Time | |
|---|---|
| Issue date: | 02/13/1980 |
| From: | Plesset M Advisory Committee on Reactor Safeguards |
| To: | Ahearne J NRC COMMISSION (OCM) |
| References | |
| ACRS-R-0862, ACRS-R-862, NUDOCS 8005020097 | |
| Download: ML20126D444 (2) | |
Text
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February 13, 1980 80050209 Honorable John F. Ahearne Chairman U. S. Nuclear Regulatory Commission Washington, D. C.
20555
SUBJECT:
NRC ACCEPTANCE CRITERIA FOR 'IEE MARK I CORTAINMERT IDNG TERM PROGRAM
Dear Dr. Ahearne:
During its 238th meeting, February 7-9, 1980, the Advisory Committee on Reactor Safeguards reviewed the NRC Acceptance Criteria for the Mark I Containment Iorg Term Program.
Eis matter was considered at ACRS Fluid Dynamics Subcommittee meetings held on May 23, 1978, Novenber 28-30, 1978, September 13-14, 1979, and Novenber 16, 1979.
During its review, the Committee had the benefit of discussions with representatives of the NRC Staff and the Mark I Owners Group.
We NRC Acceptance Criteria for the Mark I Containment Iong Term Program are intended to establish design basis loads that are appropriate for the anticipated life of each Mark I BWR facility and to restore the originally intended design safety margins to each Mark I containment system.
We Mark I program was initiated in 1975 in response to loss of coolant accident and safety relief valve (SRV) dynamic loads identified by the General Electric Company during the course of performing large scale testing for the Mark III pressure-suppression containment in 1972-1974.
A period of reevaluation resulted in issuance of the Short hrm Program Acceptance Criteria in December 1975 which established interim design bases for continued operation of the Mark I BWRs.
%e Acceptance Criteria for the Long Term Program have been developed from a program of small and full scale tests in two and three dimensional geometries.
We Mark I Owners submitted proposed loads in the " Mark I containment Program Ioad Definition Report" in December 1978 and detailed the methods to be used in plant unique analyses in the " Mark I Containment Program Structural Acceptance Criteria Plant Unique Analysis Applications Guide."
Following review of the available information, the NRC Staff determined that certain changes and clarifications to the criteria proposed by the l
Mark I Owners were necessary. We NRC Staff technical requirements were delineated in the "NRC Acceptance Criteria for the Mark I Contairunent Iong Term Program" issued in October 1979 and also in several additions to the The acceptance criteria as discussed during the 238th ACRS meeting.
additions to the Acceptance Criteria were intended, in part, to alleviate some of the difficulties the Mark I Owners had in calculating credible structural responses to SRV actuations.
2 Honorable John F. Ahearne February 13, 1980 The Committee recognizes the thoroughness of the efforts taken by the NRC Staff and the Mark I owners to resolve the generic Mark I issues and believes that the NRC Acceptance Criteria and additions, as proposed, provide a suitably conservative basis for performing the Iong Term Mark I Containment structural response analyses. %e Mark I owners indicated that they continue to have significant difficulty in calculating credible structural responses to some SRV loads and they would like to continue to work with the Staff on a generic basis to resolve these difficulties, We NRC Staff would like to complete the generic Mark I program and resolve any remaining problems as they arise from the plant unique analyses.
We Committee believes that the individual Mark I owners can work with the Staff to resolve any additional difficulties that may arise from the plant unique analyses as modifications are being made to the containment struc-tures.
%e Committee believes that the Staff should assure the adequacy of the requirements for verification of the design, fabrication, and inservice inspection of the Mark I containment modifications and, in particular, the SRV discharge piping in the wetwell airspace.
Further, in the interim period while the Mark I modifications are being performed, the Staff should investigate the potential for and consequences of a failure in the SRV discharge piping in the wetwell airspace for the existing designs.
We Committee wishes to be kept informed on this matter.
%e Committee believes that, with due consideration to the above items, the generic Mark I long Term Program can be corx:luded and the modifications to the individual Mark I BWRs can be implemented on a reasonable schedule over the next 18 months.
Sincerely, Milton S. Plesset Chairman References 1.
General Electric Company, " Mark I Containment Program Ioad Definition Report," Revision 0, NEDO 21888, December 1978.
2.
General Electric Company, " Mark I Containment Program Structural Acceptance Criteria Plant Unique Analysis Applications Guide," NEDO 24583, December 1978.
3.
U.S. Nuclear Regulatory Commission, "NRC Acceptance Criteria for the Mark I Containment Iorg Term Program," October 1979, and additions included in the February 8,1980, transcript of the 238th ACRS Meeting.
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