ML20204J216
| ML20204J216 | |
| Person / Time | |
|---|---|
| Issue date: | 08/01/1986 |
| From: | Stello V NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | Ward D Advisory Committee on Reactor Safeguards |
| References | |
| REF-GTECI-A-17, REF-GTECI-SY, TASK-A-17, TASK-OR ACRS-GENERAL, NUDOCS 8608110023 | |
| Download: ML20204J216 (6) | |
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y AUG 011986 MEMORANDUM FOR: David A. Ward, Chainnan Advisory Comittee on Reactor Safeguards FROM:
Victor Stello, Jr.
Executive Director for Operations
SUBJECT:
RESPONSE T0 ACRS C0l# TENTS ON PROPOSED RESOLUTION OF USI A-17,'" SYSTEMS INTERACTIONS IN NUCLEAR POWER PLANTS," MEMORANDUM DATED MAY 13, 1986 We have received your May 13, 1986 letter on USI A-17. Based on our understanding of the comments in the letter, we have sumarized the Comittee's major recomendations as follows:
- 1. Issue a near-tenn, partial resolution of USI A-17 which consists of
- a requirement for investigation of spatially coupled adverse sy' stems interactions (ASI) at all plants
- an infonnation letter on functionally coupled ASIS,
- a new Staridard Review Plan Section on Systems Interactions.
- 2. Develop a longer-tenn systems interaction program to establish a " pragmatic method of investigation and evaluation" and consider the use of a diverse and/or dedicated system for emergency heat removal.
- 3. Remove the added guidance regarding the application of a single failure from the proposed resolution.
In addition to the above recomendations, your letter discusses the concept of interdisciplinary industry and staff review groups responsible for identifying and investigating systems interactions issues.
1 As part of the first recommendation, the Comittee states a general agreement with the staff proposal of August 13, 1985. That proposal included a draft requiremt:nt for a focused plant review for certain spatially coupled ASIS, a generic information letter on functionally coupled ASIS, and a new Standard Review Plan section. The proposed resolution presented to the ACRS on May 7 and 8, 1986, did not include the proposed requirement or the SRP section. The staff's decision to not include a requirement was based on the actions being taken by industry in the areas of seismically induced adverse systems inter-actions and internal flooding. The SRP section was removed based on further staff consideration and staff consensus that the existing SRP adequately covers j
the area of spetially coupled ASIS.
l In consideration of the ACRS coments, we have initiated action to develop and l
support a proposed requirement for an internal flouding review.
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We intend to propose that the requirement could be satisfied by implementing the INP0 SOER which requires a flooding review. We are currently exploring ways to ensure that the SOER guidelines are adequately implemented.
With respect to seismically induced ASIS, the implementation of USI A-46 will adequately address this area. The staff is scheouled to present the final A-46 position to the ACRS Subcomittee on Safety Philosophy Technology and Criteria t
on August 5,1986 and to the full Comittee during their August meeting. During this meeting we will specifically address the A-46 seismic systems interaction review procedures.
The second part of your first recommendation states agreement with our proposed resolution for functionally coupled ASIS.
In the third part of your first recomendation, you recomended a new SRP on systems interactions. Rather than a new SRP section, the staff believes that it may be preferable to develop a Regulatory Guide to deal with ASIS for future plants. Such a Guide would then be referenced in all the necessary sections of the SRP and could encourage interdisciplinary reviews. Since this guidance would only apply to future plants, the staff intends to explore development of this guide as part of the longer-term program discussed below.
In the longer tenn, the Comittee states it would like the staff to continue to search for a " pragmatic method of investigation" suited to identify all possible effects of systems interactions. The staff believes that to a large extent the development of such methods has been investigated in plant-specific studies such as Indian Point-3 and others, and further believes that a single method suited to a global search for all possible functional and spatial systems interactions is not practical or cost effective. Rather, focused studies in specific areas of concern appear to be the preferable way to proceed. We acknowledge that the ACRS has a basic concern with what it perceives to be the staff's " limited concept of component failures." It is clear to us that the ACRS does appreciate that pursuit of this type of concern might be extremely difficult and lengthy. To adoress this general area of concern we are taking action to define a program on faulting modes which could be addressed as a separate issue. That is, this ACRS concern would be defined as a potential generic safety issue and then prioritized based on its own merits. Depending on its priority ranking it would be given appropriate attention.
With respect to the consideration of a diverse and/or dedicated system for l
emergency heat removal, we note that we have considered it in the A-17 Regulatory Analysis but concluded that its relatively high cost did not make it logical to pursue for resolution of A-17 alone. We did acknowledge that, if done for other reasons, and if implemented correctly, such an approach could adoress many aspects of the systems interactions issue.
The last recomendation involved the guidance for future plants in the area of single failure. We do not necessarily agree with the conclusion that the guidance would require a three-train safety system design, but we have decided to remove this aspect from the A-17 program. This type of guidance, with respect to electrical failures only, will be addressed as part of a separate program which will take an integrated look at a number of existing electrical system issues.
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If you have any additional questions or comments, please feel free to contact the A-17 Task Manager, Mr. Dale Thatcher, on extension 28358.
TSignedy Jacy W Roe Victor Stello, Jr.
Executive Director for Operations i
cc: Chairman Zech Commissioner Roberts Commissioner Asselstine Commissioner Bernthal SECY OGC Distribution V. Stello DSR0 Chron H. Denton/R. Vollmer J. Snfezek Central Files J. Roe D.Mossburg(001784)
EDO R/F T. Rehm PPAS EIB R/F G. Cunningham T. Speis R. Bosnak J. Taylor B. Sheron N. Anderson C. Heltemes M. Bridgers (001784) i 179)s D. Thatcher Official Copy
- Please see previous concurrence.
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