ML20206B285

Summary of ACRS Regulatory Policies & Practices Subcommittee 880810 Meeting in Washington,Dc Re USI A-47, Safety Implications of Control Sys

ML20206B285
Person / Time
Issue date:	08/19/1988
From:	Advisory Committee on Reactor Safeguards
To:	Advisory Committee on Reactor Safeguards
References
REF-GTECI-A-47, REF-GTECI-SY, TASK-A-47, TASK-OR ACRS-2598, NUDOCS 8811150400
Download: ML20206B285 (8)

Text

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b DATE ISSUED: 8/19/88 g* M i

ACRS REGULATORY POLICIES AND PRACTICES SUBCOP.MiTTEE MEETING MINUTES  ;

AUGUST 10, 1988  ;

WASHINGTON, DC l

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J PURPOSE: The purpose of the reeting was to discuss the NRC staff's response to a previous ACRS letter, dated April 12, 1988, comenting on the staff's j proposed resolutien of US! A-47, "Safety implications cf Control Systems." [

The staff, in their response listed seven assumptions and limitations that they intend to provide to ORNL for use in the Multiple System Response Frogram (MSU) with regard to establishing new generic issues to cover those {

j items not presently being resolved in the preposed resolution of US! A-47. [

l The entire reeting was open to r4mbers of the public. The meeting began at l I

2:00 p.n. and erded at 4: 30 p.m l

PEthCIPAL ATTENDEES: the prircipal attendees and particip3nts at the meeting i

mcluded

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ACRS OTHERS l H. Lewis, Chairr.,in R. Baer, RES/E!B l l C. Michelson, Pember A. Szukiewicz, RES/E!B 1 J. Carroll, Perber D. Thatcher, RES/E!B  :

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, W. Kerr, Pember C. Siess, Member f C. Wylie, Member l

D. Okrent, Consultant t G. Quittschreiber, ACRS Stsff  !

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MEETING HIGHLIGHTS  !

l 1. Executive Session Dr. Harold Lewis, Chairran, discussed the purpose of the meeting and the  ;

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( guidelines .'or holding the reeting. He noted that no written statements ,

l or requests to rake oral statements had been received. Dr. Okrent G911250400 PDR 000019 i

ACRS 1 l 2598 pg gg P

' Regulatory Policies and Practices Meeting Minutes August 10, 1988 l

stated that part of the original ACRS concern with regard to this matter involved possible false information to operators as a result of control l

system interactions. He noted that this was not presently covered in the resolution of this issue.

2, introduction and Status of USI A-47 Mr. Baer noted that the proposed resciution was issued for public I conrent the end of Ma) 1988 cfter having gone through ACRS and CRGR.

The package was revised to reflect the ACRS and CRGR coments and was released for public co rent. The public coment period did officially

'nd on Ju' 29,19E8, with only one set of corrents, from Westinghouse.

Scre additional utilities have asked for a little more time to respond.  ;

The next step is to review the comments and revise the package and to ccre back to the ACRS and the CRGR, likely in January 1989, and to [

publ sh the final resolutien package in April 1989.

3. NRC Staff Resolution of ACPS Coments Mr. S2ukiewic:, task ranager of US! A-47, provided a sumary of the proposed resolution noting that as a result of their ef# orts to look at rer-safety grade control systems they identified a limited number of reluirements, the major requirement being the issue of adequacy of the protection system against everfill. They identified certain scenarios that warranted a fix to ensure that all plants do provide overfill protection and they identified scenarios for overheat transients.

In response to questions from Dr. Lewis cencerning whether the process  ;

only requires that a safety gradd channel is required to cover a de-ficiency in a non-safety grade system. Mr. Szukiewicz agreed. In f addition they have determined that with regard to overfill protection, i since some plants did not have safety grade protection, they added technical specifiutions to the requirements for periodic verification, I testing and to making sure the required systems are operable. '

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Regulatory Policiat and Practices Meeting .'inutes August 10, 1983 l In response to questions from Dr. Lewis concerning failures in plant t corputers, Mr. Szukiewicz said they did consider computers as i j potential comon imde failure of control systems, but did not i specifically 40 in'.o the plant computer to find out the specific f I

combinations that could occur; however, they did do a bounding study.

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] In response to questions from Dr. Kerr concernir.g the ne.td for standards for performance of control systems, Mr. Szukiewicz said they did not look at a need for such a standard. The Study performed was a rechanistic study which was designed to be closed. He said that early in the program they lecked at what an unacceptable numb 3r of challenges to the protection system might be, but could ntet arrive at a consensus.

Also, they looked at the LER information to determine if there vas a certain group of plants that challenged'the protection systems more than others and concluded that all were acout the same.

I In response to numerous questions from the Subcomittee members con-j cerning whether the US! A-47 Study, if perforced early, would have caught the failures *. hat occurred at the Rancho Seco Plant during the "dropped light bulb event," it was not clear whether the performance of i this study would have prevented it. The speakers kept getting this

! event mixed up with a later Rancho Seco event and did not provide a clear answer to the questions. However, it appeared that the US! A-47 analysis assumed that licensees had met their comitment to fix things

' on B&W plants as a resul' o' that event before the US! A-47 analysis was 4 performed, such that no cle&r answer is possible. Mr. Carroll noted that he was appalled that the emergency feedwater problems uncovered l

i during the Study at Oconee Plant existed for nine and one-half years

! after the THI-2 accident. Mr. Baer noted that the staff assumes that plar.ts have been designed in accordance with the requirements. He i indicated that the only reason the "screw-up" at Oconee was found was l

because they happened to select it as the typical B&W plant. The

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Regulatory Policies and Practices Meeting Minutes August 10, 1988 problem was that even though main feedwater flow was less than needed, no tystem was installed to auhmatically initiate emergency feedwater, Mr. Baer noted that an LER search did not disclose any situation where a i

power supply to both safety-related and non-safety-related systems failed such that the failure cascaded over to redundant protection j systems, i

! Mr. Szutiewicz addressed the ACRS coments provided in the April 12 J 1988 ACRS letter. With regard to the "unduly truncated" coment. Mr.

Baer said he disagreed with the coment since the staff feels there was mutual agreerent with the AC'.S on the things they were going to do many years ago. He now feels that the residual ACRS *oncerns will be handled in the MSRP.

Dr. Lewis noted a concern that the NRC and industry hau not made the distinction between electrical system and electronic computing s ;stem vulnerabilities. Mr. Szukiewicz stated that when they did their failure analyses they felt they bounded the issue sLch that it didn't matter whether certain compenents failed.

The Subcomittae renbers and NRC staff had a lengthy discussion on possible failure modes of computers used in control systens and the expertise in the staff to perform a meaningful review.

Mr. Szukiewitz sumarized their reponse to the resolution of ACRS coments saying that they feel they have conducted the US! A-47 review within the limits that they defined and that it does conform to the task action plan. They are not planning to conduct any additional activities to review any more control system scenarios at this time. He said tney agreed to address the additional ACRS concerns in more detail and to try '

to identify, describe, and prioritize then under the MSRP.

I Regulatory Policies and Practices Meeting Minutes 5- August 10, 1988 4

4 Multiple System Response pracram Overview as it delates to USI A-47 r Mr. Baer gave an overview of the MSRP as it relates to USI A-47. The i MSRP will pick up items that the ACRS and others feel weren't directly covered by the proposed resolution of US! A-47. It will be a iiving  ;

document, being a permanent record such that if additional information i develops the item can be reviewed again.  !

l !1r. Thatcher briefly discussed the MSRP, noting that it will develop the  !

remainder of the concerns into issues to be passed on to the priori-tization process. The remaining concerns from US! A 17, USI A-46, US! '

a i A-47, and other new items as they develop, including environmental r i qualification and fire-related issues, w91 be developed and priori- l

! tired. The staff is trying to ccmbine the 30 or more issues already (

4dentified into a smaller more manageable number. [

i t l l Mr. Thatcher noted that the staff did a gentric study on four plants and }

they are looking for possible unrecognized dependencies between the [

protection and the control systems, that might allow loss of the  ;

protecticn system. Eaer said they will go back again to look for  !

possible dependencies, j J

In response to questions from Dr. Kerr concerning how low a probability (

of a sequence causing failure of a control syntem, with no protection  ;

! system trip, would have to be to ignore it, Mr. Thatcher said that for  !

prioritization purposes it would hay ( to be on the order of 10 6/ reactor l I year. Mr. Baer said that below 10 6 would be dismissed as a low  !

j priority item. If its somewhat higher they would look at a cost estimate to fix it. Above 10-5 is a high priority item aed would be fixed f

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regardless of cost.

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i Regulatory Policies and Practices Meeting Minutes August 10, 1988 1

Dr. Kerr questioned whether failure rates of protection systems were  !

looked at given fai1ures of control systems. Mr. Baer said this was not  ;

looked at in US! A-47 He added that plants do operate under a limited  !

condition for operation allowing portions of protection systems to be i out of operation for & limited tiw .

t S. PSRP Assurptions and Limitations '

Mr. Szukiewict discussed the specific ACRS corrents provided in the l April 12, 1988, letter with regard to the assumptions and limitation '

provided in the P.ay 20, 1988, letter from Stello to the ACR$. '

Mr. Fichelsor noted that with regard to US! A-47 the staff said they  !

would limit the seismic evert to the SSE, while for other issues they '

will go beyond the SSE, Mr. Baer said that some of the control systems will be leoned at under other programs which may go beyond the SSE. The  !

resperse to the ACPS letter discusses only non-safety-grade systems. [

Mr. Michelson pointed out the inconsistency of water intrusion and f

flooding being considered in USI A-17, but with regard to va! A-47, it l l will only be covered in the MSRP. The staff felt the broader concern of l US! A-17 is apprcpriate since it does consider the potential water  !

intrusion into sensitive equipment. The staff said they would look at i the resolutlen of US! A-17 to include control systems that can initiate

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transients that require protee**r with regard to water intrusion.  ;

Mr. Szukiewict discussed the ACR5 comments provided in the April 12, 1988, letter noting that witn regard to control power and air systems, they did not look at degradation of the systems but only at complete  !

loss. Degradation of these systems will be looked at in the MSRP.

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Regulatory Policies and Practices Meeting Minutes 7- August 10, 1988 Dr. Lewis exprer, sed concern over the way the staff has taken the ACRS examples and treated them as an exhaustive list. He felt the ACRS examples are symbolic of classes of things to look at. He also men-tiened an approach to use a "red team" by turning loose a few "smart  !

guys" to find new things. Mr. Baer felt the ACRS co rents were very i broad such that it was hard to odd to the ACRS list. He noted that with regard to the "red team" apm oach, the staff does send out augmented in-j spection teams (Alis) wh'.ch not only look at the initial event but also  ;

4 at broader things, i i

Mr. Michelson noted so e disagreement with the way the staff was hand-1 ling seismic events and the possibility of non-qualified equipment.

] including t.nks falling over on other non-safety equipment and breaking small pipes. He also was concerned abcut multiple small air lines  !

breaking siruitanecusly. Mr. Baer said they had not previously j understood the concern but would now "make a note of them." [

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Mr. Baer asked that the ACR$ look at the MSRP when it cores to them to l

ensure that it includes all the important items identified by the ACRS.  ;

l 1 r j 6. Executive Session  !

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l Dr. Lewis noted that this subject will be discussed with the ACRS at the j August meeH ng und that a letter may be written on this subject.

The Meeting was adjourned at 4:30 p.m. f i

l .................. j NOTE: Additional teeting details can be obtained from a transcript of f i

this meeting available in the NRC Fublic Document Room. 1717 H ,

j Street. N.W., Washington, D.C., or can be purchased from l

Heritage Reporting Corporation, 1220 L Street. N.W., Suite 600, }

) Washington, D.C. 20005,(202)628-4888.  ;

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REVISED: 7/28/88 REGULATORY POLICIES AND PRACTICES SUBCOMMITTEE MEETING AUGUST 10, 1988 ROOM 1046, 1717 H STREET, N.W.

WASHINGTON, D.C.

- TENTATIVE PRESENTATION SCHEDULE -

SPEAKER PRESENTATION ACTUAL TOPIC ORGAN!ZATION TIME TIME

1. Oper.ing Staterent H. Lewis 2:00 p.m.

2. Executive 5::; ion Subcor.mittee Members 2:05 p.m.

3. Introduction ard Status R. Baer/A Szukiewicz 10 mins 2:15 p.m.

of USl A-47 RES/EIB

4. NR". Staff Resolution of A. Szukiewicz 20 mins 2:25 p.m.

ACRS comrents (Scope, RES/EIB Connon Mode Failure Issues)

5. MSRP Overview as it D. Thatcher 30 mins 2:45 p.m.

Relates to USI A-47 RES/EIE

6. Discuss MSRP Assu ptient A. Szukiewicz/ 60 mins 3:15 p.m.

and Linitations (Stelle Baer/ Thatcher rens dated May 20, 19fd) RES/E!B as they Relate to UST A-47 Items Idertified by .he ACRS (ACRS letter, Jated April 12, 19E8)

7. Executive Session to Subcommittee Merbers 4: 15 p.m.

Discuss FutJre NRC/ACR$

Action on this !ssue

• • • ADJOURN *** 5:00 p.m.

Note 1: Approximately 30t of the presentation tire should be provided to allow for

questions and answers by the Subcommittee members.

i i Note 2: The Speakers should bring 25 collated copies of all slides and other l materials to be provided to the Subcommittee rembers and others present for j distribution before the presentation.

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