ML20006F581
| ML20006F581 | |
| Person / Time | |
|---|---|
| Issue date: | 08/11/1989 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | Advisory Committee on Reactor Safeguards |
| References | |
| ACRS-2655, NUDOCS 9002280202 | |
| Download: ML20006F581 (34) | |
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SUMMARY
/ MINUTES OF THE ACRS SUBCOMMITTEE MEETING ON GENERIC ITEMS JULY 12, 1989 BETHESDA, MARYLAND INTRODUCTION The ACRS Subcommittee on Generic Items held a meeting on Wednesday, July I
l 12, 1989, in Room P-110, 7920 Norfolk Avenue, Bethesda, Maryland, to discuss the Multiple System Responses Program (MSRP) developed by the
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Oak Ridge National Lehoratory (ORNL) for the NRC Office of Nuclear Regulatory Research (RES). The entire meeting was open to public attendance. Mr. Sam Duraiswamy was the cognizant ACRS Staff Engineer for this meeting. A list of documents submitted to the Subcommittee is included in Attachment A.
A copy of the presentation schedule for the meeting is contained in Attachment B.
ATTENDEES ACES:
C. P. Siess (Subcommittee Chairman)
I. Catton, W. Kerr, C. Michelson, F. J. Remick, D. A. Ward, and C. J. Wylie.-
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Sam Duraiswamy, Cognizant ACRS Staff Engineer.
l Principal Speakers NRC:
A. Szukiewicz, R. Baer, W.-Minners, and D. Thatcher.
,0RNL:
G. Murphy.
'l JBF 1
Associates:
M. Roberts and M. Casada.
j EXECUTIVE SESSION Dr. Siess, the Subcommittee Chaiman, convened the meeting at 8:30 a.m.
and stated that the primary purpose of the meeting was to discuss the scope and tasks associated with the MSRP. He stated that the Oi DE31cuATED ORIGINAL g
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- Generic Items Sube, Minutes July 12, 1989
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Subcommittee had received neither written conments nor requests for time -
to make oral ~ statements from members of the public.
DISCUSSION OF-THE MSRP Overview - Mr. A. Szukiewicz, RES Mr. Szukiewicz provided a brief overview, stating that the MSRP was initiated at-ORNL in 1986 to gather information on the concerns ex-pressed by individual organizations, most notably the ACRS, regarding the adequacy of the resolution of several Unresolved Safety Issues (US!s)andsomeotherNRCprogramsinaddressingsomepotentially significant safety issues. These concerns were stemmed primarily from the limitations in scope imposed by the Staf f 'during the resolution of these issues.
1 The scope of the MSRP includes the following USIs:
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' USI A-17, Systems Interactions in Muclear Power Plants
- USI A-46, Seismic Qualification of. Equipment in Operating Plants-I
- -USI A-47, Safety Implications of Control Systems in Nuclear Power Plants.
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~In addition, several other previously resolved NRC programs have been Li considered in the MSRP:
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- Environmental Qualification of Equipment
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' Seismic Qualification
- Fire Protection.
The main objective of the MSRP is to examine the issues of interest, document and define the issues as specifically as possible, end gather
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other related information for use by the NRC Staff in prioritizing these l
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I Mr. Szukiewicz stated that based on the evaluation of 31 concerns, the p.
MSRP has identified 21 potential generic issues for prioritization; ten of these 21 issues cre expected to be subsumed by the existing programs, i
He mentioned that the final report related to the MSRP is scheduled to be issued during September / October 1989.
l Mr. Michelson asked whether they have a schedule for prioritizing the potential generic issues identified by the MSRP. Mr. Minners stated that based on his discussion with the personnel responsible for l
prioritizing the generic issues, he understands that it would tale about l
a year to prioritize the 21 issues identified in the MSRP report.
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Nr. Michelson asked whether the Staff had reviewed the minutes of various ACRS Subcommittee meetings associated with the discussion of various USIs to gather the concerns expressed by members and/or consul-tants of the Subcommittees. Mr. Baer stated that the Staff is not aware of the existence of the minutes of the ACRS neetings. Mr. Casada stated l
that in the prccess of gathering the ACRS concerns for inclusion in the l-MSRP, they have looked at the ACRS letters and nieeting transcripts.
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Mr. Ward suggested that instead of sending the transcripts of the ACRS i
meetings, minutes be sent to the Staff.
Tasks Associated with the MSRP - Mr. M. Roberts, JBF Associates Mr. Roberts stated that the MSRP describes potential safety concerns expressed by others that have not been dealt with in the resolution of certain USIs and other NRC programs.
It provides information for use by the NRC Staff in assessing the relative safety significance of the concerns.
It does not include judgments regarding the validity of the concerns expressed by others.
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8 Generic Items Subc. Minutes July 12, 1989 i
Stating that during the August 10, 1988 ACRS Subcommittee meeting on Auxiliary and Secondary Systems Dr. Okrent. ACRS consultant, suggested that the Str.ff and or/ORNL interview personnel with wide operating experience to obtain information on potential safety issues, that have not been documented, for inclusion and evaluation in the MSRP, Mr.
Michelson asked whether the Staff and/or ORNL considered Dr. Okrent's suggestion. Mr. Szukiewicz stated that they talked with several fire protection experts to obtain their input. Mr. Murphy, ORNL, stated that they have evaluated reports dealing with significant operating events and obtained information for inclusion in the MSRP.
Potential Generic Issues identified In the MSRP Report Mr. Roberts discussed some of the potential generic issues identified in the MSRP report.
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- Conn.on-Cause Failures Related to Human Errors Mr. Roberts stated that one of the concerns not included in the resolution of USI A-17 is common-cause failures related to human errors. These types of failures can be pused by events such as operator errors of omission or commission, or maintenance, testing, or instellation errors.
He said that althosgh there are ongoing efforts to identify and prevent human errors and thus common-cause failures related to human errors, the adequacy of these efforts needs to be determined by the Staff.
O Dr. Siess asked why emphasis is placed on eliminating the human errors rather than eliminating the consequences of human errors.
Mr. Roberts stated that since they interpreted the original comment to mean that it was concerned about eliminating the cause rather
.than the consequences, they placed more emphasis on the elimination of human errors.
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4 c-Generic Items Subc. Minutes July 12, 1989 Dr. Siess commented that eliminating human errors is obviously a solution, but does not believe it is possible. He asked whether anyone has thought about possible ways to reduce the consequences of human errors.
Mr. Minners stated that redundant / diverse systems being used in the plants are expected to reduce the consequences of human errors.
Dr. Siess stated that there are always ways of disabling a diverse system by human action.
i Mr. Roberts stated that the following concerns expressed by the ACRS with respect to USI A-17 have already been considered in the NRC and industry programs (Attachment C, page 1):
' Lack of specific requirements for licensees to respond to specific system interaction concerns identified by USI A-17.
- Lack of specific requirements for licensees to perform spatial system interaction studies.
- Lack of dedicated interdisciplinary groups for identifying plant-specific system interactions.
Dr. Siess wondered whether there is really a need for a dedicated interdisciplinary group for identifying plant-specific system interactions.
He believes that a person with wide operating experience may be able to predict potential systems interactions.
In his opinion, looking for system interactions is a state of mind rather than an interdisciplinary effort. Mr. Minners stated that the Staff considered this issue in the resolution of USI A-17 and concluded that although it sounds like a good idea, there is really no effective way of doing this.
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k Generic ltems Subc. Minutes July 12, 1989 Dr. Siess commented that looking for systems interactions should be i
a continuing effort. Also, people should be able to observe events at one plant and extrapolate them to see how they might apply to l
L other Mantse He is not sure whether the NRC or the INPO is doing such extrapolttfons. Mr. Szukiewicz stated that the NRC Staff has
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been ruvict ng tra licensee event reports and issuing information i
i r:otices e bulletins if they found that certain events may have generle implicatitns. He believes that INPO is also taking similar AClions.
Mr. Michplser suted that unless specific requirements are imposed cn licensees, he is not sure information notices will have a major impact. He believes that the NRC should develop a good detailed gbJdante related to systems interactions for use by the licensees in idsrxifying potential problems in their plants.
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Dr. !.iess cuented that the Staf f and the industry should be aware of the fact that systems interactions will continue to occur.
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f they believe that systems interactions issue has been resolved.
l they are kidding themselves.
apependenciesBetweenSafetyandNon-SafetyRelatedSystems Mr. Roberts stated that the concern here is that simultaneous multiple failures in non-safety-related control systems may have an adverse impact on safety-related protection systems. This issue includes consideration of any and all dependencies that may exist between non-safety-related control systems and safety-related protection systems.
Specifically, this issue includes dependencies resulting from degradation of HVAC equipment, dependencies result-ing from the effects of heat, smoke, and water propagation during a fire event, dependencies resulting from the effects of flooding and/or water intrusion events, and dependencies resulting from the effects of seismic events.
P' Generic Items Subc. Minutes July 12, 1989
' Mr. Poberts stated that the existing NRC regulations seem to address this issue. However, proper implementation by the licens-ces is needed to ensure adequate protection.
Dr. Siess asked whether there would be single failure problems if the plant has been designed and operated in accordance with the existing regulations. Mr. Roberts stated that under such condi-tions, there should not be a single failure problem.
However, they have not investigated this matter to ensure that it is the case.
Mr. Beer ttated that evaluation of the operating experience showed that there were no situations in which control system failures wiped out the multiple protection systems.
Dr. Kerr commer.ted that although there were no situations in which control system failure wiped out the protection systems, there might have been certain situations in which such f611ures might have challenged the protection systems. The total effect of the failure of the control systems on the risk of plant is an important issue.
He does not believe that the existing regulations address this situation. Mr. Baer stated that operating experience has not indicated that control systems failures will affect all multiple protection systems simultaneously. Such event might happen in the future. Hc+ever, operating experience to date shows that it is a relatively low-probability event.
' Degradation of HVAC Equipment on Control and Protection Systems Mr. Roberts stated that the concern of this issue is that HVAC J
system degradation or failure could cause multiple failures in non-safety-related control systems that, in turn, could have impact on safety-related systems. He said that this concern is not specifically addressed in the existing NRC programs.
l ios Generic Items Sube Minutes July 12, 1989 Mr. Michelson commented that there is no mention in the MSRP report of the possibility of the degracotion or failure of safety-grade HVAC systems and their impact on safety-related systems.
When this issue was raised by the ACRS, it was concerned about the impact of the degradation or failure of both the safety-grade and non-safety-grade HVAC systems on safety-related systems. The possibility of adverse systems interactions resulting from the degradation or failure of safety-grade HVAC systems should be addressed in the MSRP report. Mr. Roberts and Mr. Srukiewicz stated that they will take a look at this issue and try to include Mr. Michelson's concern in the MSRP report.
' pntential Effects of Untimely Component Operation This issue is related to the concern that operation of components in some unanticipated time sequence (e.g., untimely sequencing of electric relays or untimely actuations of pumps or valves) may adversely affect plant safety.
Mr. Roberts stated that the NRC regulations do not specifically require licensees to address the potential effects of untimely component operation, nor is there any guidance for analyzing these events.
Mr. Michelson stated that loss of power during an attempt to cool the suppression chamber in a BWR after an accident m6y cause the discharge valve to the suppression chamber to stay open.
If the pump trips when the discharge valve is open, it will drain the pipes. Trying to restart the pumps when the pipes are empty may result in some serious damage. This type of scenarios has not been accounted for in the design.
He suggested that the Staff consider this type of events in the proposed generic issue related to potential effects of untimely component operation.
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C Generic Items Sube. Minutes July 12, 1989
- Propagatior. of Harsh Environments The concern in this area is that a harsh environment resulting from a design-basis accident may propagate by some unknown or unrecog-nized pathwey into another zone resulting in the exposure of equipment to environments for which they are not qualified.
kr. Roberts stated that this issue seems to have been addressed generally in the NRC regulations and guidance. However, proper licensee evaluation of propagation pathways is needed to ensure adequate protection.
Mr. Michelson commented that this proposed generic issue deals only with harsh environments created by design-basis events.
The primary concern of the ACRS was related to the environment created' by non-design-basis events outside of the containment.
He is not sure whether it has been considered in the MSRP report.
Mr.
Roberts stated that environment resulting from non-design-basis events outside of the containment is included in other parts of the MSRP report.
' Environmental Qualification of Seals, Gaskets, Packing, and Lu-bricating Fluids Associated With Mechanical Equipment This issue deals with potential detrimental effects of harsh l
environmental conditions on subcomponents of mechanical equipment, such as seals, gaskets, Lnd packing.
Mr. Roberts stated that other than the general inforraation pre-I sented in the SRP Section 3.11, no other specific guidance for environmental qualification of mechanical subcomponents exists.
Stating that there have been a lot of instances related to the failure of seals, gaskets, etc., Dr. Siess asked whether all these failures are environmentally related. Mr. Roberts stated that I
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Generic Items Subc Minutes July 12, 1989 components are supposed to be qualified to function properly in a specific environment.
In view of that, he believes that the failures of seals and gaskets could be considered as environ-mentally related.
Dr. Siess stated that there is a good data base available on the reliability of submechanical components such as seals and gaskets.
Some of the failures of these components may be owing to lack of good maintenance and some may be due to aging. He asked whether the Staff has any idea what fraction of the failures of these components could be attributable to harsh environment. Mr. Casada stated that he is not sure what fraction of these failures are environmentally related.
He believes that the Staff should explore this during the prioritization process.
In responses to a question from Dr. Siess, Mr. Roberts stated that this issue was raised originally because of lack of specific guidance for environmental qualification of mechanical subcorpo-nents.
However, he is not sure whether the qualification of these components are limited to the environment created by design-basis events. He said he would look into this matter.
l fir. Michelson stated that an equipment qualified for a certain environment may not be able to withstand a harsh environment created by unanticipated events.
If that equipment is essential to mitigate the consequences of an event, then it should be ensured that it would perform its intended function during the post-accident period. He suggested that consideration be given to look at the effects of the change in environmental conditions on the loading of essential components.
Mr. Michelson stated also that impact of the change in environment caused by water intrusion resulting from a pipe break on essential
- 4) s, Generic Items Subc. Minutes July 12, 1989 equipment should be analyzed. Mr. Szukiewicz stated that it is being considered under the flooding issue.
Mr. Michelson stated that the flooding analysis does not look at i
water leaking through ceiling and affecting some essential equip-ment.
- Flooding and/or Moisture Intrusion on Safety and hon-Safety-Related i
Equipment The concern of this issue is that flooding or moisture intrusion may directly or indirectly affect multiple trains of safety-related equipment.
Hr. Roberts stated that it seems that the Individual Plant Exami-nation (IPE) program requires that plants be examined for vul-nerabilities to internal flooding events.
He believes that guid-ance for dealing with external flooding events will eventually be included in the IPE program.
Mr. Michelson stated that during a fire, the water proofing seals associated with the electrical boxes near the location of a fire may get damaged.
In the absence of such seals, water from fire suppresg *on activities may get into the electrical boxes and travel through electrical conduits to the next floor below.
He asked whether the potential consequences of such events have been analyzed. Mr. Casada stated that moisture intrusion effects associated with fire suppression system activities are being considered in the scope of generic issue 57, Effects of Fire Protection System Actuation on Safety Related Equipment.
- Seismically Induced Relay Chatter The concern of this issue is that chattering of relays, that are not required to operate during a seismic event, may produce some
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Generic Items Sube. Minutes $1uly 12, 1989 1
unanalyzed faulting mode that may impact the operability of equipment required to mitigate the event.
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Mr. Roberts stated that Generic Letter 87-02 related to the resolu-tion of USI A-46 specifically addresses this issue. He expects
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this matter to be addressed in the Individual Plant Examination for l
ExternalEvents(IPEEE) program, i
Mr. Michelson stated that fire protection systems at some plants contain mercury relays that are very sensitive to vibration.
During a seismic event, these relays may get actuated by the vibration resulting unwanted actuation of fire protection systems and thereby causing some potential damage to certain essential equipment.
He suggested that this matter be considered in the proposed generic issue related to relay chatter.
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' fvaluation of Earthquake Magnitudes Greater Than SSE l
The concern of this issue is that adequate seismic margins may not have been included in the design of some safety-related equipment.
Seismic margin here is defined as the capability of a plant to l
sustain an earthquake larger than its SSE.
l Fr. Roberts stated that this issue seems to have been addressed in the Seismic Design Margins Program.
Mr. Michelson comented that studies performed to evaluate earth-quakes of magnitude greater than SSE do not include fire protection systems.
He wondered how the fire protection systems, that are not seismically qualified, would behave during an earthquake of magni-tude beyond SSE.
Mr. Baer stated that people performing such studies do not normally look at the behavior of non-seismically qualified equipment or systems.
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~e-1 5-Generic Items Subc. Minutes July 12, 1989 k
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Mr. Michelson stated that during a seismic event of magnitude greater than SSE, the fire protection system may behave differently j
causing adverse systems interactions.
It may also affect the diesel generators.
Even though studies related to the evaluation of an earthquake of magnitude greater than SSE do not necessarily l
evaluate the behavior of the overall plant under such condition, he wondered why people take the conclusions of such studies seriously.
He believes that the behavior of fire protection systems during an.
i earthquake of magnitude greater than SSE should be looked into.
Mr. Roberts discussed other potential generic issues identified in the MSRP report (Atte.chment C, pages 2-16).
1 SUBCOMMITTEE REMARKS Dr. Siess solicited corrents from the Subcomittee members on the following:
- Are there any issues identified in the MSRP report that are not L
worth pursuing?
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- Are there eny other issues that should be included in 1.he list of l
items identified in the MSRP report?
Mr. Wylie provided the following remarks:
' They have done a good job of identifying the issues that ought to be considered for prioritization.
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' His Subcerraittee on AC/DC Power Systems Reliability has been discussing the adequacy of lightning protection at nuclear power plants. After gathering additional information, the Subcommittee may decide whether the lightning protection issue should be pursued as a generic issue.
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Generic Items Sube. Minutes July 12, 1989 l
- The issue related to degradation of electrical power systems seems i
to deal with only the degradation of voltage.
He believes that it should deal also with degradation of frequency.
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Dr. Remick provided the following comments:
- They have done a good job of gathering various concerns and put them into a set of generic issues.
Incorporation of some of the refinements suggested by the Subcomittee during the meeting will l-help characterize some of the issues better.
- He agrees with the remarks made by some members of the Subcomittee that systems interactions issue will continue to occur and that the industry should watch for such interactions and take proper course i
of action.
If the Staff and/or the industry believe that systems interactions issue has been resolved, they are kidding themselves.
- Although minutes and transcripts of the ACRS meetings provide insights on discussions, they do not provide consensus ACRS posi-tions.
ACRS positions are expressed in its reports to the Comis-4 L
sion or to the EDO.
Mr. Michelson provided the following remarks:
- The MSRP report includes not only the positions expressed by the ACRS in several of its reports but also includes the concerns raised by individual members during the Subcommittee and full i
Committee meetings.
He believes that they had done a good job in gathering the concerns included in ACRS reports as well as the concerns raised by individual ACRS members during several meetings.
He expects that the concerns expressed by him and others during the course of this Subcommittee meeting will be considered by the Staff and ORNI. prior to finalizing the MSRP report.
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e Generic Items Subc Minutes July 12, 1989 j
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- Although some issues raised previously by the ACRS or individual members may not have been considered in the MSRP, he believes that j
they have done a good job in consolidating most of the concerns.
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- He reiterated that the impact of the degradation or failure of safety-related HVAC system on the performance of essential equipment should be explored.
i Dr. Kerr stated the following:
- He also believes that they have done a good job in pulling together various concerns.
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- In process of prioritizing these issues, the Staff should make an effort to determine how some of these issues will affect the reliability of the overall plant.
Dr. Catton stated that he agrees with the remarks made by Mr. Michelson.
SUBCOMMITTEF ACTION The Subcommittee decided to reconnend to the full Connittee that there is no need to write a report to the Connission on this matter, since there is no real action proposed by the Staff at this time.
Dr. Siess suggested that cognizant Subconruittee Chairmen 104 at the adequacy of the priority rankings proposed by the Staff when available.
Dr. Siess agreed to provide a Subconmittee report on this matter to the full Committee during the July 1989 ACRS meeting.
ACTION SUGGESTIONS, AND AGREEMENTS
- The Subcommittee decided to recommend to the full Conrnittee that there is no need for writing a report on the MSRP at this time.
,9' Generic Items Sube. Minutes July 12, 1989 l
- Dr. Siess suggested that cognizant Subcommittee Chairmen review the adequacy of the proposed priority rankings of those issues iden-tified in the MSRP report when made available to the ACRS.
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- Mr. Michelson suggested that Section 7.3.11.4 of the MSRP report related to the issue on Evaluation of Heat, Smoke, and Water Propagation Effects Resulting from Fires needs some clarification.
The Staff and ORNL agreed to make changes as necessary.
' Mr. Michelson stated that the Staff and/or ORNL ensure the correct-ness of the statement included in the last paragraph of Section i
7.3.16.4 of the MSRP report which states that "There were no malfunctions, false indications, system resets, or abnormal occur-rences of any form in power plant control systems." The Staff and ORNL agreed to look into this.
- Hr. Michelson suggested that the impact of the degradation or failure of safety-related HVAC systems on the performance of the safety-related equipment be evaluated. The Staff agreed to look into this.
Dr. Siess thanked all participants and adjourned the meeting at 11:45 a.m.
l NOTE:
Additional meeting details can be obtained from a transcript of this meeting available in the NRC Public Document Room, 2120 L Street, N.W., Washington, D.C. 20006, (202) 634-3273 or can be purchased from Heritage Reporting Corporation, 1220 L Street, N.W., Suite 600, Washington, D.C. 2000s, (202) 628-4888.
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1 LIST OF DOCUMENTS SUBMITTED TO THE i
GENERIC ITEMS SUBCOMMITTEE JULY 12, 1919 1.
Presentation Schedule.
2.
Draft ORNL Report, Multiple System Responses Program - Identifica-tion of Concerns Related to a Number of Specific Regulatory Issues, June 1989 (Internal ACRS Use Only).
3.
Portions of the Minutes of the August 10, 1988 Auxiliary and Secondary Systems Subcommittee Meeting Related to the Discussion of a preliminary Draft Report on MSRP.
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ACRS Reports on USI A-17, A-47, and A-46.
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NRC Staff's Responses to ACRS Comments on the Resolution of Generic Issue 43, Air Systems Reliability.
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ATTACHMENT A
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I PRESENTATION SCHEDULE t
t ACRS SUBCOMMITTEE MEETING ON THE
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GENERIC ITEMS I
JULY 12. 1989 ROOM P-110, 7920 NORFOLK AVENUE.
I BETHESDA, MARYLAND i
t ACRS CONTACT:
Sam Duraiswamy 1
301-492-9522 i
NOTE:
- Presentation Time should not exceed 50% of the Total Time.
allocated for a specific item.
The remaining 50% of the time is reserved for the Subcomittee questions and answers by the Staff or its contractors.
- Nutrber of copies of the presentation materials to be submitted to the Subcomittee:
25 copies.
TOTAL l
PRESENTAT10N ITEM PRESENTER TIME ACTUAL TIME 1.
EXECullVE SESSION Subcommittee 15 min 8:30 - 8:45 am 2.
PRESENTATION BY THE NRC 517JT AND ITS CONTRACTORS v
15 min 8:45 - 9:00 am Andy)Szukiewicz
- Introduction /0verview (RES
- Discussion of the Mike Roberts /
90 min 9:00 - 10:30 am Scopo/ Tasks of the Myron Casada Multiple System (JBFAssociates)
Responses Program George Murphy (MSRP)
(ORNL)
- BREAK ***
15 min 10:30 - 10:45 am
- Continue Discussion of 90 min 10:45 - 12:15 pm the MSRP 3.
SUBCOMMITTEE REMARKS Subcomittee 15 min 12:15 - 12:30 pm i
- ADJ0 URN ***
12:30 pm A rrmnear. 8 L
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LACK OF SPECIFIC ACTION RELATED TO SYSTEMS INTERACTION (MSRP SECTION 7.3.1)
LACK OF SPECIFIC REQUIREMENTS FOR LICENSEES TO RESPOND TO o
SPECIFIC SYSTEMS INTERACTION (SI) CONCERNS IDENTIFIED IN USI f
A-17 LACK OF SPECIFIC ACTIONS OR REQUIREMENTS IMPOSED ON LICENSEES o
BY THE NRC FOR PERFORMING SPATIAL SI STUDIES LACK OF DEDICATED INTERDISCIPLINARY GROUPS FOR IDENTIFYING o
PLANT SPECIFIC sis NRC/ INDUSTRY ACTIONS; o MSRP TO IDENTIFY SPECIFIC ISSUES GENERIC AND PLANT SPECIFIC sis CAN BE IDENTIFIED BY CURRENT o
" LESSONS LEARNED" PROGRAMS SUCH AS:
INPO OPERATING EXPERIENCE PROGRAMS NRC REVIEW OF LERS UTILITY OPERATING EXPERIENCE REVIEWS (POST TMI)
I THE IPE GENERIC LETTER (GL 88 20) REQUESTS LICENSEES TO IDENTIFY o
PLANT SPECIFIC VULNERABILITIES TO SEVERE ACCIDENTS STATUS:
l o GENERAL CONCERNS ARE CONSIDERED IN NRC AND INDUSTRY PROGRAMS l
o SPECIFIC MSRP ISSUES AS DEFINED AND PRIORITIZED b77AcHMENT C C-/
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FAILURE MODES OF DIGITAL COMPUTER CONTROL SYSTEMS (MSRP SECTION 7.3.4) f POTENTIAL FOR ADVERSE INTERACTIONS BETWEEN COMPUTERIZED i
o CONTROL SYSTEMS AND SAFETY-RELATED PROTECTION SYSTEMS USE OF DIGITAL COMPUTER CONTROL SYSTEMS FOR SAFETY-RELATED o
PURPOSES NRC/ INDUSTRY ACTIONS:
GDC 22 REQUIRES INDEPENDENCE OF REDUNDANT CHANNELS OF THE o
PROTECflON SYSTEM GDC 24 REQUIRES SEPARATION OF CONTROL AND PROTECTION o
SYSTEMS GI A 19," DIGITAL COMPUTER PROTECFION SYSTEMS"IS INVESTIGATING o
THE USE OF DIGITAL COMPUTERS IN NUCLEAR POWER PLANTS' SAFETY-RELATED SYSTEMS - TO BE PRIORITIZED ANSI /IEEE-ANS-7-4.3.21982," APPLICATION CRITERIA FOR PROGRAMMABLE i
o DIGITAL COMPUTER SYSTEMS IN SAFETY SYSTEMS OF NUCLEAR POWER GENERATING STATIONS," AND RG 1.152 (ACCEPTS ANSI /IEEE-ANS-7-4.3.2-1982) PROVIDE GUIDANCE FOR ADDRESSING THE ISSUE IN GI A-19 STATUS:
o FIRST ISSUE ALREADY ADDRESSED LtY SEPARATION AND b
INDEPENDENCE CRITERIA IT APPEARS THAT GI A-19 WILL ADDRESS TI-lE SECOND ISSUE o
'o TO BE CONFIRMED BY THE PRIORITIZATION PROCESS i
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SPECIFIC SCENARIO NOT CONSIDERED IN USI A-47 (MSRP SECTION 7.3.5)
SCRAM WITHOUT TURBINE TRIP INCLUDING RETURN TO CRITICALITY o
RESULTING FROM OVERCOOLING THE PRIMARY SYSTEM NRC/ INDUSTRY ACrlONS:
o Gl
- 144,
" SCRAM WITHOUT A TURBINE / GENERATOR TRIP,"
WILL INVESTIGATE THIS ISSUE - TO BE PRIORITIZED i
STATUS:
IT APPEARS THAT GI 144 WILL ADDRESS THIS ISSUE o
TO BE CONFIRMED BY THE PRIORITI7.,ATION PROCESS o
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SPECIFIC SCENARIO NOT CONSIDERED IN USI A-47 (CONT.)
(MSRP SECTION 7.3.5)
STEAM GENERATOR OVERFILL LEADING TO A MAIN STEAM LINE BREAK o
AND A STEAM GENERATOR TUBE RUPTURETHAT WOULD INVOLVE THE BLOWDOWN OF MORE THAN ONE STEAM GENERATOR NRC/ INDUSTRY ACTIONS:
THREE SEPARATE USIs HAVE INVESTIGATED TUBE RUPTURES o
USI A-3, " WESTINGHOUSE STEAM GENERATOR TUBE INTEGRITY" USI A 4, "B&W STEAM GENERATOR TUBE INTEGRITY" 4
USI A-5, "CE STEAM GENERATOR TUBE INTEGRITY" NUREG 0844 DESCRIBES AN INTEGRATED NRC PROGRAM TO RESOLVE o
- THESE THREE ISSUES GI 135, " STEAM GENERATOR AND STEAM LINE OVERFILL,"
WILL o
ADDRESS THE POTENTIAL EFFECTS OF STEAM GENERATOR OVERFILL ON SECONDARY SYSTEM COMPONENTS t
STATUS:
IT APPEARS THAT USIs A-3, A-4, A-5, AND GI 135 WILL. ADDRESS THIS o
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ISSUE TO BE CONFIRMED BY THE PRIORITIZATION PROCESS o
f 12
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FAILURE MODES RESULTING FROM DEGRADED ELECTRIC POWER SOURCES (MSRP SECflON 7.3.7) i l
EFFECTS OF ELECTRICAL SYSTEM DEGRADATION (i.e., UNDERVOLTAGE o
AND OVERVOLTAGE) MAY NOT HAVE BEEN ADEQUATELY EVALUATED i
i NRC/ INDUSTRY ACTIONS:
GDC 17 AND 18 PROVIDE REQUIREMENTS FOR THE DESIGN OF o
ELECTRIC POWER SYSTEMS SRP 8.1, 8.2, 8.3.1, 8.3.2, AND BTP PSB-1 PROVIDE GUIDANCE FOR o
SATISFYING THE GDC GDC AND SRP DO NOT SPECIFICALLY REQUIRE UNDERVOLTAGE OR o
OVERVOLTAGE OF ELECTRIC POWER SYSTEMS TO BE INVESTIGATED IEB 79-27, " LOSS OF NON-CLASS-IE INSTRUMENTATION AND CONTROL c
POWER SYSTEM BUS DURING OPERATION," REQUIRED LICENSEES TO REVIEW LOSS OF POWER EVENTS FOR THEIR PLANTS IEN 8916 DESCRIBES THE POTENTIAL FOR AN UNDERVOLTAGE EVENT o
IN A PLANT'S DC POWER SYSTEM THAT COULD LEAD TO A TOTAL LOSS OF AC POWER
' STATUS:
NOT SPECIFICALLY ADDRESSED BY EXISTING PROGRAMS o
1 o TO DE PRIORITIZED 1
c.5 c
u P
i FAILURE MODES RESULTING FROM DEGRADED l
COMPRESSED AIR SYSTEMS (MSRP SECTION 7.3.8)
EFFECTS OF AIR SYSTEM DEGRADATION (i.e., GRADUAL LOSS OF AIR o
PRESSURE, UNDERPRESSURIZATION, AND OVERPRESSURIZATION) MAY NOT HAVE BEEN ADEQUATELY EVALUATED NRC/ INDUSTRY ACTIONS:
I SRP 9.3.1 PROVIDES GUIDANCE FOR THE DESIGN OF COMPRESSED AIR o
i SYSTEMS RG 1.68.3 PROVIDES GUIDANCE FOR TESTING OF COMPRESSED AIR o
SYSTEMS. ADDRESSES TOTAL LOSS OF AIR PRESSURE BOTH SUDDEN AND GRADUAL o GI 43,
" RELIABILITY OF AIR SYSTEMS,"
PROVIDED A
LIMITED EVALUATION OF GRADUAL LOSS OF AIR PRESSURE AND UNDERPRESSURIZATION - SUGGESTED THAT IT BE PRIORITI7ED SEPARATELY 9 THE GI 43 GENERIC LETTER (GL 88-14), ONLY ADDRESSED TOTAL LOSS OF AIR SYSTEM PRESSURE h
IEN 80-40 AND 88-24 DESCRIBE EVENTS THAT CAUSED SAFETY-RELATED o
EQUIPMENT TO FAIL l
C-6 15 l'
,j e
FAILURE MODES RESULTING FROM DEGRADED COMPRESSED AIR SYSTEMS (CONT.)
(MSRP SECI' ION 7.3.8) i NRC/ INDUSTRY ACTIONS (CONT.h IEN 82-25 DESCRIBES AN EVENT IN WHICH SAFETY-RELATED VALVES o
DID NOT GO TO THEIR FAIL-SAFE POSITION UPON GRADUAL LOSS OF AIR PRESSURE
-o NUREG-1275 REPORTS ON AN AEOD REVIEW OF OPERATING EXPERIENCE RELATED TO AIR SYSTEM PROBLEMS STATUS:
GL 88-14 ADDRESSES THE ASPEC1' OF TOTAL LOSS OF AIR SYSTEM o
OVERPRESSURIZATION AND GRADUAL LOSS OF AIR PRESSURE ARE o
NOT ADDRESSED o TO BE PRIORITIZED C-7 9
16
~
HEAT, SMOKE, AND WATER PROPAGATION EFFECTS RESULTING FROM FIRES (MSRP SECTION 7.3.11) o MULTIPLE TRAINS OF SAFETY-RELATED EQUIPMENT COULD BE AFFECTED BY HEAT, SMOKE, AND WATER PROPAGATION EFFECTS RESULTING FROM FIRES NRC/ INDUSTRY ACTIONS:
GDC3,10CFR50.48, AND 10CFR50, APPENDIX R ESTABLISH REQUIREMENTS o
FOR PROTECTION OF REDUNDANT TRAINS OF EQUIPMENT REQUIRED TO ACHIEVE PLANT SHUTDOWN AND FOR ESTABLISHINO A FIRE PROTECTION PLAN i
SRP 9.5.1, BTP CMEB 9.5-1, GL 81-12, " FIRE PROTECTION RULE," AND GL o
86-10,
" IMPLEMENTATION OF FIRE PROTECTION REQUIREMENTS,"
PROVIDE GUIDANCE FOR SATISFYING THE REGULATIONS. SRP 9.5.1 SPECIFIES THAT SAFETY-RELATED EQUIPMENT SHOULD BE PROTECTED FROM THE EFFECTS OF FIRE, HEAT, SMOKE, AND WATER EXPOSURE STATUS:
ISSUE APPEARS TO BE ADDRESSED GENERALLY IN THE REGULATIONS o
AND GUIDANCE.
HOWEVER, PROPER LICENSEE EVALUATION OF t
PROPAGATION PATHWAYS IS REQUIRED TO ENSURE ADEQUATE PROTECFION o TO BE PRIORITIZED c-8 4
19 j
-o, SYNERGISTIC EFFECTS OF HARSH ENVIRCNMENTAL CONDITIONS (MSRP SECTION 7.3.12)
SYNERGISTIC EFFECTS OF HARSH ENVIRONMENTAL CONDITIONS MAY o
NOT NAVE BEEN ADEQUATELY ADDRESSED BY THE LICENSEES NRC/ INDUSTRY ACTIONS:
o GDC 4
AND 10CFR50.49 ESTABLISH THE REQUIREMENTS FOR ENVIRONMENTAL QUALIFICATION OF EQUIPMENT AND SPECIFICALLY INCLUDE THE CONSIDERATION OF SYNERGISTIC EFFECTS SRP 3.11, RG 1.89, IEEE STD 323, AND NUREG-0588 o
PROVIDE GUIDANCE FOR CONDUCTING ENVIRONMENTAL QUALIFICATION REQUIRE THAT SYNERGISTIC EFFECTS THAT HAVE BEEN IDENTIFIED MUST BE INCLUDED IN THE ANALYSIS NO PRESCRIPTIVE GUIDANCE IS PROVIDED FOR IIOW THESE SYNERGISTIC EFFECTS SHOULD BE ANALYZED c-9 r
i i
SYNERGISTIC EFFECTS OF HARSH ENVIRONMENTAL CONDITIONS (CONT.)
(MSRP SECTION 7.3.12) l NRC/ INDUSTRY ACTIONS (CONT.h o - NUREG/CR-0275, NUREG/CR-3538, NUREG/CR-3588, NUREG/CR-3863, NUREG/CR-4301, NUREG/CR-4536, NUREG/CR-5313, AND EPRI NP-1558 DESCRIBE EFFORTS TO STUDY THE EFFECTS OF ENVIRONMENTAL SYNERGISMS ON VARIOUS MATERIALS AND COMPONENTS STATUS.
o THE REGULATIONS REQUIRE THAT SYNERGISTIC EFFECTS BE CONSIDERED AND ADDRESSED WHENEVER POSSIBLE DURING TESTING THERE IS LITTLE GUIDANCE AVAILABLE FOR PERFORMING SUCH ANALYSES OR TESTS o TO BE PRIORITI7ED l
l C -to 21 I
v'-
.m
j. (* ' -
a, FIRE SUPPRESSION SYSTEM ACTUATIONS ON
~
SAFETY AND NON-SAFETY-RELATED EQUIPMENT (MSRP SECTION 7.3.14) o POTENTIAL ADVERSE EFFECT ON SAFETY-RELATED COMPONENTS EITHER THROUGH DIRECT CONTACT WITH SUPPRESSION AGENTS OR THROUGH INDIRECT INTERACTIONS WITH NON-SAFETY-RELATED COMPONENTS THAT ARE AFFECTED BY FIRE SUPPRESSION SYSTEM ACTUATION EVENTS NRC/ INDUSTRY ACTIONS; GDC 3 AND 10CFR50, APPENDlX R SET FORTH THE REQUIREMENTS FOR o
THE PROTECTION OF SAFETY-RELATED EQUIPMENT FROM INADVERTENT OPERATION OF FIRE SUPPRESSION SYSTEMS GI 57," EFFECTS OF FIRE PROTECflON SYSTEM ACTUATION ON SAFETY-o RELATED EQUIPMENT," ADDRESSES THIS ISSUE. ORIGINALLY ASSIGNED A MEDIUM PRIORITY, GI 57 IS UNDER CONSIDERATION TO BE MADE A HIGH PRIORITY ISSUE IEN 83-41, AND 87-14 DESCRIBE TWO EVENTS WHERE ACTUATION OF o
FIRE SUPPRESSION SYSTEMS HAD AN ADVERSE EFFECT ON SAFETY-RELATED EQUIPMENT STATUS:
IT APPEARS THAT GI 57 WILL FULLY ADDRESS THIS CONCERN o
TO BE CONFIRMED BY THE PRIORITIZATION PROCESS o
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i n
L.
- ~ ~ ~
~
o.
l 0
f SEISMICALLY INDUCED SPATIAL AND FUNCFIONAL INTERACTIONS i
(MSRP SECTION 7.3.16) j POTENTIAL FOR SEISMIC EVENTS TO FAfL MULTIPLE TRAINS OF SAFETY-o RELATED EQUIPMENT THROUGH SPATIAL AND FUNCTIONAL l
INTERACFIONS NRC/ INDUSTRY ACTIONS:
o GDC 2
REQUIRES STRUCTURES,
- SYSTEMS, AND COMPONENTS IMPORTANT TO SAFETY BE ABLE TO WITHSTAND THE EFFECTS OF 1
EARTHQUAKES SRP 3.7.2, 3.7.3 AND RG 1,29 PROVIDE GUIDANCE FOR DESIGNING L
o SYSTEMS AND SUBSYSTEMS SUCH THAT THEY COMPLY WITH THE GDC L
THE USI A-46 GENERIC LETTER (GL 87-02) REQUESTED THAT LICENSEES o
l
' VERIFY THE SEISMIC ADEQUACY OF EQUIPMENT BY COMPARISON WITH AN EXPERIENCE DATA BASE STATUS:
ADEQUATE GUIDANCE FOR MEDIUM AND LARGE SIZE PIPES o
DOES NOT APPEAR TO SPECIFICALLY ADDRESS FAILURES OF CERTAIN o
SMALL PIPING AND THE POTENTIAL FOR ASSOCIATED SYSTEM INTERACflONS o TO BE PRIORITIZED C - / 2-u 2
--r-
':;tg, fe;
.,yvc A:. '
L SEISMICALLY INDUCED FIRES (MSRP SECflON 7.3.17) lt o PO112NTIAL FOR SEISMICALLY INDUCED FIRES TO CAUSE MULTIPLE.
l FAILURES OF SAFETY-RELATED EQUIPMENT l
NRC/ INDUSTRY ACTIONS:
GDC.2 AND. 3 REQUIRE THAT SAFETY-RELATED EQUIPMENT BE
'o PROTECTED FROM THE EFFECTS OF EARTHQUAKES AND FIRES NUREGICR-5042, EVALUATION OF EXTERNAL HAZARDS TO NUCLEAR
\\
o L
- PLANTS IN.THE UNITED STATES, INVESTIGATED THE POTENTIAL FOR i
h HAVING SEISMICALLY INDUCED FIRES L,
4 STATUS:
l o THE NRC STAFF HAS SPECIFICALLY STATED (BTP CMEB 9.5-1) THAT L.
- ONLY LIMITED FIRE PROTECTION IS REQUIRED IN POST EARTHQUAKE SITUATIONS L
l
- o TO BE PRIORITI7ED
.t C-/3 u
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- c. **
4
' SEISMICALLY INDUCED FIRE SUPPRESSION SYSTEM ACTUATIONS i
(MSRP SECTION 7.3.18) l o - POTENTIAL FOR SEISMICALLY INDUCED FIRE SUPPRESSION ACFUATION TO CAUSE MULTIPLE FAILURES OF SAFETY-RELATED EQUIPMENT I
\\
L NRC/ INDUSTRY ACflONS:
GDC 3 STATES THAT SAFETY-RELATED EQUIPMENT MUST BE ABLE TO o
i SURVIVE AN SSE i'
10CFR50, APPENDIX R STATES THAT DEDICATED SHUTDOWN CAPABILITY e
MUST BE PROVIDED WHERE REDUNDANT SYSTEMS MAY BE SUBJECTED TO ' DAMAGE. FROM INADVERTENT FIRE SUPPRESSION SYSTEM l
ACTUATION GI 57," EFFECTS OF FIRE PROTECTION SYSTEM ACTUATION ON SAFETY-o RELATED EQUIPMENT," WILL INVESTIGATE.ALL AVAILABLE DATA ASSOCIATED WITH -COMMON CAUSE INITIATORS OF MULTIPLE FIRE PROTECTION SYSTEM ACTUATIONS, INCLUDING EARTHQUAKES STATUS:
o IT APPEARS THAT GI 57 WILL INCLUDE CONSIDERATION OF y
SEISMICALLY INDUCED FIRE SUPPRESSION SYSTEM ACTUATION TO BE CONFIRMED B.Y THE PRIORITIZATION PROCESS o-(:
C -/9 "I
27 t
p;.. x r
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=
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SEISMICALLY INDUCED FLOODING (MSRP SECTION.7.3.19).
POTENTIAL FOR SEISMICALLY INDUCED FLOODING EVENT TO CAU e
f MULTIPLE FAILURES OF SAFETY-RELATED EQUIPMENT NRC/ INDUSTRY -ACflONS:
o: GDC 2 AND 4 REQUIRE PROTECTION OF SAFETY-RELATED EQUIPMENT FROM,THE EFFECFS OF SEISMIC AND FLOODING EVENTS INCLUDING i
LOCAs y
L o SRP 3.4.1 PROVIDES GUIDANCE FOR EVALUATING PLANT FLOOD L
PROTECTION io ' NUREG/CR-4776 INVESTIGATED THE RESPONSE OF SEISMIC CATEGORY-i I TANKS TO EARTHQUAKE EXCITATION o
- o IPE '
FOR EXTERNAL EVENTS WILL.
INVESTIGATE PLANT
- VULNERABILITIES TO ALL EXTERNAL EVENTS,-
1NCLUDING EARTHQUAKES-
'i
' STATUS:
o: NOT SPECIFICALLY ADDRESSED BY EXISTING PROGRAMS h
7 TO BE ADDRESSED IN IPE FOR-EXTERNAL EVENTS o TO~BE CONFIRMED BY THE PRIORITIZATION PROCESS i.
C -If~
1
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F. a
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EFFECTS OF HYDROGEN LINE RUPTURE (MSRP SECTION 7.3.22) o HYDROGEN LINE ' RUPTURE WITH SUBSEQUENT FIRE AND/OR:
EXPLOSION COULD DAMAGE MULTIPLE TRAINS OF SAFETY-RELATED
{
EQUIPMENT
--NRC/ INDUSTRY ACTIONS:
BTP CMEB 9.5-1 STATES THAT HYDROGEN LINES IN SAFETY-RELATED e
AREAS:
SHOULD BE DESIGNED TO PREVENT HYDROGEN CONCENTRATIONS FROM EXCEEDING 50 %
OF THE I.,0WER FLAMMABILITY LIMIT IN THE EVENT OF A HYDROGEN LINE BREAK-o GI'106," PIPING AND THE USE OF HIGHLY COMBUSTIBLE GASES IN VITAL AREAS," ADDRESSES PROTECTION OF SAFETY-RELATED ' EQUIPMENT FROM-THE EFFECTS OF HYDROGEN LINE BREAKS - MEDIUM PRIORITY NUREG/CR-3551 -
INVESTIGATED THE SAFETY IMPLICATIONS OF o
PRESSURIZED GAS SYSTEMS IN NUCLEAR POWER PLANTS STATUS:
o IT APPEARS THAT G1106 WILL FULLY ADDRESS THIS CONCERN
'o TO BE CONFIRMED BY THE PRIORITIZATION PROCESS t
1
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