ML18051A306
| ML18051A306 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 01/13/1983 |
| From: | Mattson R Office of Nuclear Reactor Regulation |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML18043B117 | List: |
| References | |
| TASK-2.K.3.07, TASK-TM NUDOCS 8302090523 | |
| Download: ML18051A306 (3) | |
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UNITED STATF.S NUCLEAR REGULATORY COMMISSION WASHINGTON, C. C. 20555 JAN l 3 1983 MEMORANDUM FOR:
Darrell G. Eisenhut, Director, Division of Licensing
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FROM:
SUBJECT': -
Reference:
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Roger J. Mattson, Director, Divisio11 of Systems Integration RESPONSE TO QUESTIONS REGARDING.THE VALIDITY OF NUREG-0737 ITEM II.K.3.7 Memorandum, D. Diianni to D. Eisenhut, dated 4/1/82,
Subject:
Multi-Plant Action Item II.K.3.7 - Power Operated Relief Valve Opening Probability (with.
memorandum from D. Diianni to R. Reid, dated 10/4/79 and 2/19/80 attached as Enclosures 1 and 2, respectively)
Your memorandum to me, dated 4/19/82,
Subject:
Action Plan Item II.K.3.7, asked for my review and reaction to the comments presented in the reference memorandum.
Based upon my conversation "'ith R. Purple on 12/29/82, I agreed -
to look _into the status of our response.
{--lf-It is *difficult to provide co.rrrnents on the reference mem0randum and {ts* two*
enclosures since all three documents were written over a period of time covering two-and-a-half years and cover several different but interrelated aspects of PORV and block va1ve re1iabi1ity.
Many of the issues raised are. under review by OST, DE, and OS I.
The principal concern expressed in the reference memorandum is the need for possible cance11ation or redirection from a technical point of view of NUREG-0737 Item II.K.3.7, "Evaluation of PORV Opening Probability During Overpressure
- Tran~ients.
11 The memorandum points out*that Item II.K.3.7 requires licensees of B&W-designed operating reactors to provide additional analyses of anticipated transients which indicate the sensitivity of PORV challenges to (l) the variation in core phys.ics parameters which may occur in the plant cycle; (2) s~ngle failures in mitigation systems; and (3) transients which do not actuate the anticipatory reactor trips. The results of the analyses were to be used to determine whether the expected frequency of PORV openings from overpressure transients was less than 5%, that a basis for installing an automatic block valve closure system could be established. The reference memorandum then provides several reasons why a decision to automate the block valve based upon the results from this action does not appear adequate.
T.he following comments apply to Item II.K.3.7 in general and the reference memorandum:
- 1. The ori gi na 1 purpose of II. K. 3. 7 was not to provide a data base".:.--'-f,,,..o.____ __
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~arrel~ G. Eisenhut.. JAN 1 3 19S3 A
detennining whether an *automatic ?ORV closure system would be required on B&W plants. The II.K.3.7 anaiyses were requested to help the staff quantify the expected lift frequency (or cha 11 enge rate) of the PORV based upon the revised setpoi nts for the PORV and high pressure reactor trip and the in.;.
stall ati on of anticipatory reactor trips. for 1 oss of feedwater and 1 oss of load. Thus, II.K.3.7 originally dealt only with PORV challenge rate for overpressure transients and did not deal directly with. PORV/block valve reliability. Note that the review responsibility for II.K.3.7 *has always been assigned to DST/RRAB.
- 2. The NUREG-0737 item dealing with automatic PORV closure -system criteria is II.K.3.2. This item required that all licensees provide a report that analyzes the probability of a small-break LOCA caused by a stuck-open PORV* or safety valve.
The report was to consider all modifications which were made subsequent to the TMI-2 accident.to reduce this probability.
The current rrodifications would be considered sufficient improvement in reactor safety if they reduced the probability of a smal1mbreak LOCA caused by a stuck-open PORV such that it was not a significant contributor to the probability of a small-break LOCA.due to a11 causes. The report was also required to contain an evaluation of the*effects of an automatic PORV isolation system.
Review of this item is also being done by DST/RRAB.
- 3. Subsequent to the issuance of the reference memorandum in 4/82~ RRAB detennined. that the review of Iter:'l II.K.3.2 (under MPA F-37) would
- subsume the II.K.3.7 information. *Thus, RRAB is no longer.pursui"ng a**
separate review of data required under II~K.3.7.
- 4.
Several aspects of the reference tJernorandum (and its enclosures) are directly related to the review effort RRAS-is perfonning under II.K.3.2.
As a result, D. Di Ianni has *discussed his concerns with the RRAB lead *reviewer.
RRAB has prepared a detailed respon~e to his concerns.
The response is presently undergoing RRAB management revie~.
- 5. Certain portions of the reference memorandum (and its enclosures) describe recomnended ways to improve the reliability of the PORV/b1ock valve mech-anical design and discuss test program considerations.
I believe that most of the items discussed have been considered in the past by the staff. Some of the items are covered in NUREG-0737, Item II.D.1, "Relief and Safety Valve Testing.
11 These areas should be more appropriately addressed by DE/MEB.
- 6.
One of the key points discussed throughout the reference memorandum (and its enclosures) is that the 11 fundamental safety requirements of the PORV and its block.valve need to be defined.
11 I agree with this corrment.
Jl.s a result of an event that took place at Robinson 2 on 11/30/81, OSI conducted an overall evaluation of the role-of PORVs and block valves in PWR plant safety and in the licensing process. The evaluation covers Chapter
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Darre11 JAA 1_ 3 7983 15 analyses, multiple failure events, and procedures, as well as recent staff positions taken at the TMI-1 and Diablo Canyon ASLB hearings. This evaluation is 'presently' in the OSI concurrence chain and should be trans-mitted to you shortly. The evaluation should provide satisfactory answers.
to most of the concerns expressed in the reference memorandum that fall within DSI's area of responsibility.
D. Diianni has been placed on distribution for a copy of this report.
If D. o*; Ianni 's concerns are riot answered as a resu1 t of reading the report -*
discussed in item 6 above, he should contact R. Capra of my staff (X29625) to discuss the matter further.
Enclosure:
Reference memorandum (w/enclosures) cc:-,_.* R._ Purp 1 e. _
R. Vollmer J. Knight R. Bosnak T. Speis M. Ernst
_ A. °Thadani G. Lainas R. Clark
- o. Diianni./
B. Sheron R. Capra
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