ML18051A474
| ML18051A474 | |
| Person / Time | |
|---|---|
| Site: | Palisades  |
| Issue date: | 06/06/1983 |
| From: | Diianni D Office of Nuclear Reactor Regulation |
| To: | Minners W Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML18043B117 | List: |
| References | |
| NUDOCS 8307050513 | |
| Download: ML18051A474 (6) | |
Text
':.*
THRU:
FROM:
UNITED ST ATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555
- u**
1"'8" i_! t'i 0
-~ j Warren Minners, Acting Chief Safety Program Evaluation Branch Division of Safety Technology
'1 Robert A. Clark, Chief---/'-°'.~"'.\\.(~t.L:.c Operating Reactors Branch #3 Division of Licensing Dominic C. Diianni, Project Manager Operating Reactors.Branen ffe3 Division of Licensing
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I l-c:-1---
SUBJECT:
PROPOSED GENERIC ISSUE.
11PORV AND BLOCK VALVE RELIABILITY" NRR Office Letter* No. 40 "Management of Proposed Generic Issues" provides guidance for the systematic processing,. management and resoJution of potential generic issues. Based on these guidelines,. the attachment proposes that the PORVs be* considered safety grade and be requtred to be operable during plant operation with appropriate operability r:equi rements.
The task fa~ improving the reliability of the* PORV and block va-lves is to
- assure: the opening and: closing functions of this-valving system as dictated by various plant transients and. to mitigat~the consequences of potential plant accidents. Operating plants with-installed PORVs and block valves have unknown operability Timits in that when these valves have been called to operate, they have stuck open on* numerous occasions.
In other cases*
where-the PORVs have leakage-problems, the PORVs. are blocked which could lead. ta. adverse consequences* if the safety valves are challenged and stick open. It has been* estimated* that 551of alT Westinghouse plants are operating with blocked off PORVs so as not to exceed the technical specificati"on leakage limits for the reactor coolant systems. It is a known fact. that* these valves. operating under-existing service conditions will in no way last for the* life of toe plant without proper maintenance programs.
On this basis, therefore, the generic issu*e described.in.this attachment is bein*g µ*reposed in order that these concerns can be aqequately addressed and to es tab 1 i sh PORV and block valve sys.terns as safe.ty grade components.
In accordance witrr* the auidel ines of NRR Office Letter No.* 40, the attached proposed generic issue information is being forwarded for your evaluation and disposition. *I am available to discuss this matter in further detail if you wish.
XA Copy H~~Been SenfJO:eQR'
Attachment:
As stated cc:* See.next page
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- c. Lain as Mattson Vollmer Thadani Knight Cherny Sheron Houston Chow
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Attachment GENERIC ISSUE INFORMATION ON PORV AND BLOCK VALVE RELIABILITY The following informati.on provides the safety significance and scope of the proposed generic issue in regard to improving the reliability pf the PORV and block valves.
This information is based on the guidance given in the NRR Office Letter No. 40 "Management. of Proposed Generic Issues" dated March 14, 1983.
I..
Suggested Title of Proposed Generic Issue.
"PORV and Block Valve Reliability" II.
Hhat.is the known, suspected or potential deficiency in the technical basis of existing staff guides *or requirements?
.,.,_.:... ______ --*=*-... _...... ___ 4,
- The existing staff guides or requirements do not adequately address the safety conseqences of a malfunctioning PORV or block valve during plant transients.
In addition, guides or re~uirements for esta~lishing adequate reliability of the PORV or block valve* do not exist. Thus, guides O:"' re-quirements must be established to assure th.at*these valves will perfo*rm their opening and closing functions as dictated by plant transients to reduce the.Potential of plant accidents (i.e., SBLOCA, challenges to SV) *.
III.
What present specific safety requirements (e.g., SRP, Regulatory Guide, Rule) appear to be inadequate or in doubt?
Our existing SRP, Reg. Guide or rules do not address the PORV nor the block valves, since these valves are not now considered safety grade components.
The proposed generic issue will establish the requirement of this valve system as a safety grade component.
The purpose of these requirements is to assure that the PORV and block valves will perform their open*ing and closing functions during plant transients and protect against challenges of the safety valves during overpressure transients.
IV.
If a new reqirement is proposed, what is the proposed requirement?
Provide, to the extent possible, a value-impact assessment.
The proposed requirements would address the following for the PORV and block valves.
- 1.
Operability limits for both valves.
- 2.
Adequate maintenanc~ programs based on the valve operability limits (i.e., 1 above).
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Backup definition of the block valve for the PORV.
- 4.
Revised technical specification requirements incorporating PORV and block valve reliability.
In preparing a value impact assessment, the following should be considered:
- 1.
Valve operability limits would have *to be determined by valve testing or other means to establish the longevity of both PORV and block valves.
Such testing has not been performed for valves currently in use by the utilities. Valve testing would be performed by either valve manufac-turers, INPO, EPRI or NSSS vendors.
However, before initiating such a test pro~ram, the valve manufacturers are to be consulted to assure that 'such information (i.e., valve longevity) cannot be obtained by other means.
- 2.
Plant modifications would be required by the utilities based on the final system design criterion (i.e., PORV/block valves).
Such modi-fications would include both mechanical, I&C and electrical engineering.
The magnitude of the modifications would vary for each utility depending upon the final design criteria and the existing installation *
- 3.
Based on the operability limits, a maintenance program would have to be developed by the utilities; this would include input from the valve vendors, quality..assurance requirements, prep a r.at ion of procedures and training of oersonnel.
- 4.
Efforts would be required by the utilities if the requirement to auto-mate the operation of. the block valve is imposed by the staff. However, this requirement may not be necessary based on the combination of the improved valve reliability and requirements imposed by the technical specifications (note 5 below).
- 5.
Finally, the utilities would be required to upgrade the technical specificat~ons to include limited conditions of operation for these valves and the necessary surveillance program.
V.
What new information must be developed either to confirm the adequacy of the current technical bases or to define new requirements that would restore adequate protection?
The fundamental safety requirements of the PORV and its block valve need to be defined.
These fundamental requirements would include the operability limits of PORVs and block valves, the backup supporting function of the block valve to the PORV, the operational benefits of these valves during plant transients, and technical specification requirements based on valve reliability would be defined.
None of this exists now and therefore should be developed under the proposed program.
' ' VI.
What actions are being taken (if any) or should be taken on operating plants to correct the suggested deficiency?
By whom (organization and individual) are these actions being taken?
There is no action being taken to resolve this proposed deficiency for operating plants.
To resolve this proposed deficiency requires the coor-dination and efforts of many disciplines (i.e., Materials, Mechanical Reactor Systems, I&C and El~ctrical Engineering, Standard Technical Speci-fication Branch, and DL).
This coordination is needed since these dis-ciplines are interrelated when one considers the effects of these disciplines on the PORV and block valves.
VII.
If the issue is related to another generic issue (e.g., TMI Action Plan Item) identify the generic issue and the area of issue overlap.
The following are all of the TMI Action Plan items i~directly related to this proposed generic issue.
- 1.
II.D.1 Relief and safety valve test requirements
- 2.
II.D.3 Valve position indic~tion
- 3.
II.K.3.1 Auto PORV isolation
- 4.
II.K.3.2 Report on PORV failures
- 5.
II.K.3.3 Report on sv & RV failures and challenges
- 6.
II.K.3.7 Evaluation of PORV opening probability (this item is part of item II.K.3.2)
- 7.
II.K.3.11 Justification for use of certain PORVs.
- 8.
II.G.l Emergency Power for Pressurizer Equipmen~
The EPRI test program is in direct response to action item II.D.l which addresses issues involving pipe geometries/loads during valve operation and valve capacities {i.e., liquid, two phase and steam) but does not address the operability limits of relief valves which is central in now this proposed generic issue.
All other TM! action items deal with the reduction of PORV challenge frequencies by changing setpoints, modifying pressure control systems and modifying procedures to make operators more aware of valve positions.
In no way do these action items address the PORV reliability to perform the opening and closing functions during plant transients which is the major concern of this proposed generic issue.
Further information regarding this proposed generic issue as it relates to the TM! action items is addressed in the memorandum from Ed Chow to Askoh Thadani dated March 14, 1983, attached.
However, the information derived from these TMI action items may complement this proposed generic issue.
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' l V!II. Is anyone currently working on this issue? If so, name and organization.
No.
IX.
Name *of person supplying information:
Date provided.
Dominic C. Diianni.
From 10/4/79 to present; note References Item X.
X.
Provide references as appropriate (Memoranda, NUREGs~ SRPs, etc.).
Memoranda:
D. c. Diianni to R. w. Reid dated October 4, 1979.
Do c. Di Ianni to R. w. Reid dated Februa~y 19, 1980.
D. c. Di Ianni to Darrel 1 G. Eisenhut dated April 1, 1982.
Roger J. Mattson to Darrell G. Eisenhut dated January 13, 1983
- Ed Chow to Ashok Thadani dated Ma~ch 14, 1983.
Roger J. Mattson to DarreH G~ Eisenhut dated March 27, 1983.
- Commission Briefing on Status of Decay Heat Removal in recent Combustion Engineering designed Plants dated April 4, 1~83.
Victor ~tello to Harold Denton dated April 11, 1983.
Harold Denton to Victor Stello dated April 27, 1983.