ML19260C573
| ML19260C573 | |
| Person / Time | |
|---|---|
| Issue date: | 12/04/1979 |
| From: | Cherney F Office of Nuclear Reactor Regulation |
| To: | Bosnak R Office of Nuclear Reactor Regulation |
| References | |
| REF-GTECI-A-09, REF-GTECI-SY, TASK-A-09, TASK-A-9, TASK-OR NUDOCS 8001080025 | |
| Download: ML19260C573 (6) | |
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04M DEC MEMORANDUM FOR:
R. J. Bosnak, Chief, Mechanical Engineering Branch, DSS FROM:
F. C. Cherny, Section Leader, Mechanical Engineering Branch, DSS
SUBJECT:
TRIP REPORT - MEETING OF ASME SECTION III SUBGROUP ON PRESSURE RELIEF, NOVEMBER 27-28, 1979 The referenced meeting contained several post-TMI-2 related items and was held at the United Engineering Center in New York City. A synopsis of the items of interest to NRC is contained in the attachment to this memoranaum.
Information on' all of the agenda items is available in my file.
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F. C. Cherny, Sectich' Leader Mechanical Engineering Branch Division of Systems Safety cc w/att:
R. Mattson, DSS J. Knight, DSS T. Novak DSS J. 01shinski, DSS W. Minners, DSS Tb3 rim n i _ DSS _
S. HanaueF, DSS )
M. 5tolzencerg, RSR W. Anderson, DES E. Brown, DES
- 0. Reiff, RSR C. Graves, DSS V. Noonan, D0R K. Wichman, D0R MEB Members 80 010 80 O c15 1700 261
ASME CODE COMMITTEE: ASMF Section III Subgroup on Pressure Relief DATES OF MEETING: November 27-28, 1979 NRC REPRESENTATIVE:
F. C. Cherny MEETING ATTENDED AND REPORTED BY:
F. C. Cherny
- 1) EPRI Full Scale Safety and Relief Valve Test Program - MPR Recomendations The meeting was attended by a representative of MPR Associates, a Utility consulting engineering firm based in Washington, D.C.
MPR is under contract to EPRI to develop a FWR safety and relief valve test program which will be responsive to the full scale performance verifica-tion testing recommended in NUREG-0578 "TMI-2 Lessons Learned Task Force Status Report and Short Term Recommendations". To date MPR has completed an initial survey of the types and sizes of safety and relief valves in service on operating PWR's. They have also surveyed the types of transients the. valves would be expected to relieve system fluid under and what the physical state of the fluid might be f.e., steam, sub-ccoled liquid etc. Based on the information they have developed to date they have come up with a recommended test program which consist., sf testing a total of three safety valves and three power operated relief valves under a variety of fluid conditions for a total of some 148 tests.
The results of the surveys performed and a tabulation of the recommended tests can be found in the attachment to this report which was handed out to each of the Subgroup *1 embers at the meeting.
The stated reason for discussing the details of the program with the Subgroup was to obtain any comments the members might have, but particularly with regard to the information gathered as to the types and capacities of valves currently in service.
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. The program as proposed does not include provision for testing valves under ATMS conditions i.e., two phase and subcooled water at pressures 0
in the range of 2800 psi - 4000 psi and temperatures from 650 F - 700 F.
I asked about ATWS tests and the MPR representative responded that at the present time there were no plans to include testing under such conditions in the program.
I mentioned that a letter was in preparation which the NRC would be sending to the Utilities recommending that ATMS testing be included in the EPRI program. The MPR representative felt that the letters probably would have a positive effect on getting such tests included in the program.
One further comment is worthy of note. MPR envisions that the entire program described in the attachment could be undertaken at one of the existing valve testing facilities in the U. S.
th slight modification.
Specifically the Wyle facility at Norco, Cal, was menthned as having the necessary hardware on site to make the needed modifications. Apparently a specific test facility has not been selected by EPRI as yet.
- 2) Modification of NB-7000 of ASME Section III to incorporate NUREG-0578 Safety and Relief Valve Design and Testing Recommendations into the Code.
I proposed that an item be formally placed on the agenda for the next Subgroup meeting to allot time at the meeting to.iiscuss a specific proposal for changes to NB-7000 which would incorporate all of these Safety and Relief Valve recommendations into the Code. I volunteered to draft the proposal.
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The proposal will include a requirement for direct indication of valve position and also a requirement that valves be full size prototype tested on ali
- uids and under all conditions under which they would be expected to perform in service. With regard to the full size testing I noted that for the currently manufactured and NV stamped valves, the EPRI program would be expected to satisfy such a requirement.
If such testing is added to the Code, it would be applicable only to new future valve designs.
Judging from the initial reaction, it would appear there is at least a reasonable chance of obtaining the Subgroup agreement with such a proposal.
- 3) Overpressure Protection of ASME Class 2 and 3 Components Under System Emergency and Faulted Conditions When the Subgrop redrafted NC-7000 in mid 1978 it was decided not to include any pressure limits for Emergency or Faulted Conditions because no low probability overpressure even6s could be identified which would have a potential for raising system pressures higher than 10 percent over design pressure. However, at the Main Committee level the redraft was negative balloted specifically because it did not contain overpressure limits under Emergency Conditions whereas NB-7000 did. Also NC-3000 presumably contained appropriate stress limits as had NB-3000 which could be referenced in NC-7000, as was done in NB-7000, in order to establish in terms of stress level an Emergency Condition pressure limit.
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In the course of arriving at a suitable NB-3000 stress limit to reference for Emergency Conditicsn in NB-7000, considerable interface took place with the Subgroup on Design which has direct responsibility for all of the Code Para. 3000 requirements.
In the ensuing interface discussions the Subgroup on Design changed one or more stress limits in NB-3000 making them slightly more conservative than they had been. The revision included adding a specific limitation on the amount of the total component stress level that could result solely from pressure loadir.g.
In order to resolve the negative ballot on NC-7000, the Subgroup on Pressure Relief agreed to add overpressure protection requirements for Emergency Conditions.
As had been done for NB-7000 the Subgroup on Pressure Relief Chairman requested the Subgroup on Design to review the proposed NC-7000 requirements which, as had been done for NB-7000, would reference Service Limit C.
Concurrently, by letter of Dec. 13, 1978 R. J. Bosnak wrote to the Subgroup on Design Chairman reiterating the background of the changes made to,
Service Limit C in NB-3000 when it was referenced in NB-7000 and pointing out that as currently written both NC and NO-3000 appear to permit different allowable pressures for different components f.e., between vessels designed to different design options and also piping versus other components.
By letter dated September 25, 1979 the Subgroup on Design Chairman requested that the Chairman of the Sub oup on Pressure Relief revise both NC and t
ND-7000 to include a limit on system pressure of 10 percent over design pressure, the same as the Upset Condition limit, for both System Emergency and Faulted Conditions.
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This is more conservative than what was done for Class 1 components in NB-7000; but, for Emergency Conditions, the Subgroup agreed to change both NC and ND-7000. I was assigned to draft the changes. No action will be taken for Faulted Conditions as none was taken in NB-7000.
Additionally, after the char.ges to NC and ND-7000 are completed as requested by the Subgroup on Design, they will be sent to the Subgroup on Design for a final review and with the request that the changes be made to NC and ND-3000 to remove any references, as now exist, to higher allowable pressures for some components than the ten percent limit which has been requested for NC and ND-7000. These changes to NC and ND-3000 will have to be published in the Code concurrent with publication cF the 10 percent overpressure limit for system Emergency Conditions.
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