ML20217K037
| ML20217K037 | |
| Person / Time | |
|---|---|
| Issue date: | 10/10/1997 |
| From: | Callan L NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | Shirley Ann Jackson, The Chairman NRC COMMISSION (OCM) |
| References | |
| NUDOCS 9710220382 | |
| Download: ML20217K037 (10) | |
Text
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i pnuoriqk UNITED STATES p
NUCLEAR REGULATORY COMMISSION f
WASHINGTON D.C. 2055H001
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October 10, 1997
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MEMORANDUM TO: Chairman Jacksen i
FROM:
L Joseph Callan, -
Execu'ive Director f Operations
SUBJECT:
SCOPE OF STRUCTURES, SYSTEMS AND COMPONENTS (SSCs)
COVERED IN THE VOLUNTARY APPROACH TO PROVIDING RELIABILITY AND AVAILABILITY INFORMATION At the September 2,1997 briefing on the PRA implementation Plan, you asked for a wntten response to previous questions raised by the Commission regarding the scope of the SSCs covered by the maintenance rule and those in the industry's voluntary approach to providing reliability and availability data. In SECY.97-101, the staff recommended that the Commission accept the voluntary approach and provided an evaluation of the suitability of the proposed data. It included a limited description of the data that would be available from the Institute of l
Nuclear Power Operations'(INPO's) new Equipment Performance and Information Exchange (EPIX) System for the maintenance rule systems of high safety significance. This memorandum provides additional clarification on how the scope of the SSCs covered by the maintenance rule compares to the scope of equipment for which dati will be made available through EPIX.
The documentation for the EPIX system states that the scoping criteria will be consistent with the scope of SSCs covered by the maintenance rule. INPO proposes to do this by collecting information on functional failures of components that are within the scope of the maintenance rule, including components in both the systems of high safety significance and the systems of low safety significance in addition, the EPIX system includes data on failures of components in balance-of-plant (BOP) systems resulting in significant power reductions that are not necessarily in the scope of the maintenance rule. As we understand it, data on structures
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would not be reportable to EPIX. The specific data to be provided for different groups of y
components in EPIX will depend on whether a componunt is in a system designated as a til Safety System Performance Indicator (SSPI) system, a maintenance rule system of high safety significance, a maintenance rule system of low safety significance, or a BOP system. The g@g attached diagram' (Figure 1) taken from an attachment to a March 21,1997 letter from Ralph g$t Beedle, Nuclear Energy Institute, to me describing the data to be provided voluntarily illustrates sa q') Jw
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O' From *Equiprnent Performance a id information Exchange System, Maintenance Rule and Reliability Q-Information Module (EPIX)." Preliminary February 1997. After discussion with industry representatives, the NRC
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staff has determined that the preferred terminology for
- risk-significacit* and *non-risk significant* is *high safety I
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significance" and
- low safety significance," respectively.
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Chairman Jackson the four levels of the EPIX scope. Also attached is Figure 2 from the same document that shows the differences in the data to be provided for each EPIX scope category identified in Figure 1. Note that the reliability and availability information to be provided for the SSPI systems is very similar to that of the proposed rule on this subject. Less detailed information is to be provided for non SSPI systems, especially low safety significance and BOP systems. The staff discussed how it would address these differences in deriving reliability and availability parameters in SECY-97-101.
Attachments 1,2, and 3 from that document are also provided for your reference. Attachment 1 provides additional detail on the data provided for components in EPIX SSPI scope (red coded in Figures 1 and 2) and the high safety significance systems scope (orange coded in Figures 1 and 2). Attachments 2 and 3 show the PRA parameters that the staff will need to estimate for PRA applications and the methods the staff will use to overcome some of the limitations in using the voluntary data for estimating these parameters.
if you have any additional questions, please call me (415-1700) or Pat Baranowsky (415-7493).
Attachments: As stated cc:
Commissioner Dicus Commissioner Diaz I
Commissioner McGaffigan l
SECY OGC OCA OPA CFO CIO Distribution:
RRAB RF DHickman SPD RF/ Action No. 97-60 Jrosenthat AEOD RF JMitchell, OEDO OEDO RF TOMartin, OEDO File Center JBlaha, AO Public HThompson, DEDR DOCUMENT NAME: H:\\BMB\\ SCOPE.FOU
- See Previous Concurrence To receive a coin of this document. Indicate in the box *C" copy Wo attach /enci"E" copy w/ attach /enci"N" no copy 0FFICE RRAS/RRAB E
RRAS/RRAB E
C:RRAB E
D:SPD E
NAME BBrady*
SMays PBaranowsky*
CERoW*
DATE 10/8/97
/ /97 10/8/97 10/8/97 OFFICE D:AEOD E
D.OD/NRR E
A:DEDE E
ED4 )E NAME TTMartin' SCollins*
AThadani*
LJNbn DATE 10/ 9/97 10/9/97 10/10/97 10/
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O Figure 2 EPIX Data l
l CIR Reliability Data l
Component Component Component Actual Estimated Actual Estimated Actual Estimated l Zone i
I Information Failure Operating Operating Number Number Number Number l
Record Record Ilours llours of Nontest oftest Total ofTotal (CIR)
(CFR)
Demands Demands Demands Demands Yes when failure Required N/A Required Required N/A N/A l Red (nonfailure occurs dependent) l Orange Yes when failure Optional Required Optional Optional Optional Required j
(nonfailure occurs dependent) l
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Optional Optional Optional l Yellow when failure when failure Optiona'l Optional Optional occurs occurs
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Green when failure when failure Optional Optional Optional Optional Optional Optional results in results in generation generation loss
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BRIEF
SUMMARY
OF BASIC DATA PROVIDED BY INDUSTRY UNDER THE VOLUNTARY APPROACH $
Data Needed Data Provided for Systems Data Provided for Other la SSPl Scope Systems of "High Safety.
Significance" Under the Maintenance Rule Failures.
Failures provided Failures provided Demands - Test Estimated average test Estimated average total demands demands (one time estimate)
Demands - Non-Test Counted non test demands Demands by Type Not broken down into types Not broken down into types beyond test vs non-test at all Run Times Actual operating bours Estimated average operating hours (one-time estimate)
Unplanned Unavailability Unplanned unavailable time Unplanned unavailable time-2 for each repair for each repair Planned Unavailability Planned unavailable hours for No train for each month (from SSPI)
Unavailability Due to Unavailable hours for each EPIX provides uncianned Support System train for each month (from unavailable times directly SSPI) for components in support systems, but not olanned unavailable hours Concurrent Unavailability Ability to screen for No significant occurrences
' Unless otherwise noted, data are provided by EPIX on a component basis.
From time of failure discovery to time of return to service.
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IDENTIFICATION OF PRA PARAMETERS AND ASSOCIATED DATA ELEMENTS The followina PRA eouations indicate the parameters that need to be estimated:
Equation for the total unavailability of standby equipment.
Or
= Ao + % A.t,+ U where: q,
= demand failure probability (failure to start or change state)
% A,t,
= equipment unavailability due to failure from environmental stresses U
= equipment unavailability due to out of service for repair or maintenance t,
= test interval For operating equipment such as pumps, EDGs, or control valves, a term is added to the equation to represent failure during the mission time d""""'
Q(t) = 1 - e where: A(r) = the running, or operating, failure rate t(m) = the mission time Data from a reliability database are needed to estimate q, A., U, and A(r). The terms t, and t(m) are unique for each application, and are determined by plant operations and design characteristics.
To estimate q, the number of failures to start or change state (N,) and the number of demands on the component to start or change state (N,) are needed.
q, = N, / N, To estimate A, the number of failures due to environmental stresses (N,,)
and the component on-line time (t,) are needed.
A, = N,, / t, To estimate U, the planned outage time (t,,n), the unplat ned outage time (t
), and the component time on-line (t,) are needed.
U = (t,o +to)/t, To estimate A(r), the number of failures during operation, or while running (N,,), and the accumulated run time (t,) are needed.
A(r) = N,, / t, 1
EV.1LUATION OF REllABILITY AND AVAILABILITY INFORMATION The followina table indicates the kinds of efforts needed to compensate for weaknesses in the voluntary data in estimatina PRA para.neters:
F RA PARAMETERS AVAILABILITY UNDER VOLUNTARY POSSIBLE WORK-AROUNDS APPROACH N,(The number of PRA Available in EPIX on a component basis, Na work-arounds needed.
feifures, needed as the including the specific type of demand numerator to estimate q,)
associated with the failure.
N,(The number of valid For components in the SSPI reporting scope.
Work-around for SSPI scope components demands, needed as the EPIX will contain total component level involves obtaining further breakdown of demand denominator to estimate q,)
demands partitioned as " test" (estimated) type data by:
estimating test demands from Tech Specs and "non-test" (counted).
IST requirements and other requirements estimating actual and spurious demands from LERs comparing with demands in EPIX For components not in SSPI scope EPIX will Work-around for non-SSPI components involves contain cotoponent level demands, not estimating demands as above, and comparing partitioned by type, and estimated once.
with EPIX estimates.
N,,(the number of PRA Failures available in EPIX on a component No work-arounds needed.
failures due to basis using cause coding and supplemental environmental stress, descriptions needed as the numerator to estimate A,)
t, (Component standby The plant state is recorded for all failures in No work-arounds needed.
on-line time, needed to EPIX. Other sources available to the NRC estimate component failum (e.g. monthly operating reports) provide the rate, A,)
plants' operational states.
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PRA PARAMETERS AVAILABILITY UNDER VOLUNTARY POSSIBLE WORK-AROUNDS I
APPROACH ty (Component planned For components in SSPI scope, train level For components in SSPI scope, no work-around outage time, needed to planned outage time is recorded. EPIX needed.
estimate component outage contains identifiers that relate components to unavailability, U)
SSPl trains.
For components not in the SSPI scope.
For components not in the SSPI scope, the work-planned outage time is not available in EPIX arounct is to develop estimates of planned or SSPl.
outage time considering information such as:
planned outage of other systems surveying plant practices relationship of planned and unplanned outages fraction of unplanned demands that occur during planned outages t,(Component ur' planned EPIX contains this information on a No work-around needed.
outage time, needed to component basis, for all components of estimate component outage interest. (In addition, SSPI contains train unavailability, U) level unplanned outage time.)
t, (Support system outage SSPI contains train outages due to support No work-arounds are needed.
time, used to estimate system failures or outages, for the systems I
outage unavailability, U) in the SSPI scope.
EPIX provides failures and unplanned The work-around is to estimate planned outages outages directly for risk significant support (as discussed above under ty).
systems outside the SSPI scope.
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PRA PARAMETERS AVAILABILITY UNDER VOLUNTARY POSSIBLE WORK-AROUNDS APPROACH N,,(Number of component EPIX contains component level failures No work-arounds are needed failures during component recorded agains! 'he discovery method, operation, needed to including those discovered while running, for estimate the component all components of interest.
operating failure rate, A(r))
t,(Operating time for EPIX contains component level operating For SSPI-scope components, no work-arounds rotating equipment and time, counted for components in the SSPI needed.
control valves, needed to scope.
estimate the component operating failure rate, A(r))
For non-SSPI components, EPIX provides For non-SSPI components, the staff will use one-time estimates of operating time.
information from LERs and testing information (Tech Spec, IST) and operating failure rate data from similar components. The estimates are expected to contain more uncertainty than the counted values discussed above.
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.- :T; PRA' PARAMETERS -
' AVAILABILITY UNDER VOLUNTARY POSSIBLE WORK-AROUNDS APPROACH Concurrent train unavailable SSPI currently collects unavailable hours on For SSPI-scope trains, no work-arounds are hours a monthly basis. For the systems in SSPl needed.
scope, this provides sufficient information to identify potential concurrent outagcs for further investigation.
For Non-SSPI systems, EPIX does not For non-SSPI components, concurrent directly provde component or train unavailable hours cannot be estimated since concurrent outage information.
planned maintenance outages are not recorded in EPlX. Some mstances will meet LER reportog requirements.
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