ML20212H446

Forwards Suppl Info,As Discussed with NRC During 990812 Telcon,To Support Risk Informed Inservice Testing & GL 96-05, Periodic Verification of Design-Basis Capability of Safety-Related Movs

ML20212H446
Person / Time
Site:	San Onofre
Issue date:	09/28/1999
From:	Scherer A SOUTHERN CALIFORNIA EDISON CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GL-96-05, TAC-MA4509, TAC-MA4510, NUDOCS 9910010132
Download: ML20212H446 (42)

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6 E 50U1Hf RN CAtHORNIA A. Edwud Scherer F

EDISON 0%.,

An LDISON IN11.RNA110NAL" Company September 28, 1999 U. S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555

Subject:

Docket Nos. 50-361 and 50-362 Risk-informed inservice Testing and GL 96-05 (TAC Nos. MA4509 and MA4510)

Saa Onofre Nuclear Generating Station Units 2 and 3

Reference:

Letter from A. E. Scherer (SCE) to the Document Control Desk (NRC),

dated June 17,1999,

Subject:

Risk-Informed inservice Testing and GL 96-05 (TAC Nos. MA4509 and MA4510), San Onofre Nuclear Generating Station, Units 2 and 3 Gentlemen:

This letter provides supplemental information as discussed with the U.S. NRC during a phone call on August 12,1999. This information supplements information provided to the NRC, by the above reference, to support risk informed inservice testing and j

Generic Letter (GL) 96-05 " Periodic Verification of Design-Basis Capability of Safety-Related Motor-Operated Valves" testing at San Onofre Units 2 and 3.

The questions discussed in the phone call and the Southern California Edison responses to those questions are provided as Enclosure 1. Enclosure 2 provides an updated Section 3, implementation and Monitoring Program, of the San Onofre Nuclear

- Generating Station Risk-informed Inservice Testing Program to replace the Section 3 pages provided by the above reference. Enclosure 3 provides the revised Risk-j Informed inservice Testing Program Description to replace the one submitted with the j

above reference. Revised sections of Enclosures 2 and 3 are identified by change bars in the right hand margin.

I 010025 ju !$$ UEfg (O

P. O. Box 128 San Clemente. CA 92674 0128 949-368 7501 Fax 949 368-7575 J

1 Document Control Desk if you have any questions or need additional information regarding this matter, please call me or Mr. Jack Rainsberry at (949) 368-7420.

Sincerely, Enclosures cc:

E. W. Merschoff, Regional Administrator, NP.C Region IV J. A. Sloan, NRC Senior Resident inspector, San Onofre Units 2 & 3 L. Raghavan NRC Project Manager, San Onofre Units 2 and 3 l

s ENCLOSURE 1 The Southern California Edison Company (SCE)

Risk-informed Inservice Testing Program (RI-IST)

Response to NRC Questions l

l

n Enclosuro 1 RI-IST and GL 96-05 Page 1 of 6 NRC Question 1 Questions 6 through 11 of the formal Request for Additional Information (RAl)

(reference 1) will be handled separate from the Risk informed Inservice Testing (RI-IST) submittal (reference 2).

The Southern California Edison Company (SCE) Response:

Acknowledged.

NRC Question 2 in Question 12, the staff requested the licensee to address the conditions on use of Code Case OMN-1 listed in Generic Letter (GL) 96-05 (reference 3). The licensee's consideration of those conditions is not apparent in the RAI response.

SCE Response:

The SCE positions for these GL 96-05 conditions for use in OMN-1 are the following:

GL 96-05 Condition

"(1)

When implementing the code case, the staff notes as an additional precaution that the benefits (such as identification of decreased thrust output and increased thrust requirements) and potential adverse affects (such as accelerated aging or valve damage) need to be considered when determining the appropriate testing for each Motor Operated Valve (MOV).

SCE Position SCE will ensure procedurally that the potential benefits (such as identification of decreased thrust output and increased thrust requirements) and potential adverse affects (such as accelerated degradation due to aging or valve damage) are considered when determining the appropriate testing for each MOV.

GL 96-05 Condition

"(2)

The code case states that the maximum inservice test frequency shall not exceed ten years. The staff agrees with this condition of a maximum test interval of ten years based on current knowleage and experience in

[

addition to this maximum test interval, where a selected test interval I

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i RI-IST and GL 96-05 Page 2 of 6 extends beyond 5 years or 3 refueling outages (whichever is longer), the licensee should evaluate information obtained from valve testing conducted during the first 5-year or 3 RFO time period to validate assumptions made in justifying the longer test interval. Based on performance and test experience, a licensee may be able to justify lengthened MOV periodic verification intervals.

SCE Position i

For MOVs specifically, SCE's submittal limits the maximum inservice test interval to 6 years (3 refueling cycles). As detailed in the Program Description (Enclosure 3 of the same letter transmitting the responses to these questions), all testing on valve groups containing more than one valve is based on a stagger test model. The stagger test model evenly distributes component testing over the maximum interval. RI-IST program procedures will contain guidance to ensure performance and test experiences from previous tests are evaluated to j

justify the periodic verification interval.

GL 96-05 Condition i

i

"(3)

Some licensees are daveloping programs for IST that include consideration

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of risk insights. As a part of an industry pilot effort, two licensees have submitted requests to utilize this approach to determine IST frequencies for certain components, in lieu of testing these components per the frequencies specified by the ASME code. Licensees involved in these IST programs that seek to implement the ASME code case need to specifically address the relationship of the code case to their pilot initiative.

SCE Position The relationship of the code case to SCE's Rl-IST submittal is detailed within reference 2, in the Program Description initially supplied in reference 4 and revised by Enclosure 3 of the same letter transmitting these responses.

Briefly, the Integrated Decisionmaking Process (IDP) either confirms or adjusts the initial risk ranking developed from the probability risk assessment (PRA) results and provides t qualitative assessment based on engineering judgement i

and expert experience to determine the fina! safety significance categories. This J

qualitative assessment compensates for limitations of the PRA, including cases where adequate quantitative data is not available. The IDP considerations are documented for each individual component to allow for future repeatability and i

scrutiny of the categorization process.

The scope of the IDP includes both categorization and application. The IDP identifies components whose performance justifies a higher categorization, i

j determines appropriate changes to testing strategies, and identifies compensatory measures for Potentially High Safety Significant (L-H) components, orjustifies the final categorization. The IDP also concurs on the

f i

Enclosura 1 RI-IST and GL 96-05 Page 3 of 6 test interval and basic test methodology for components categorized as Low Safety Significant Component (LSSC). The IDP results in components categorized as LSSC, Potentially High Safety Significant (L-H), or High Safety Significant Component (HSSC).

NRC Question 3 In question 12, the staff requested the licensee to address the use of risk insights to evaluate potential extensions of the quarterly exercise intervals of high risk MOVs. The licensee's evaluation of the risk significance of such extensions is not apparent in the RAI response.

SCE Response:

For high-risk valves SCE intends to initially retain the stroke time testing (quarterly, cold shutdown, or refueling interval based on practicability) as required by the Code of Record. Not specifying this testing was an error of omission in the Program Description initially provided by reference 4.

Corrections to the Program Description, as well as the original submittal pages are included in Enclosures 2 and 3 of the letter transmitting this response.

When sufficient data accumulates and analysis indicates extension of the current stroke interval may be acceptable (i.e., exercising on a refueling interval basis pursuant to OMN-1 paragraph 3.6.3), the Integrated Decisionmaking Process (IDP) determines the acceptability of the extension. The IDP ensures the cumulative risk measures remain consistent with the acceptance guidelines specified in the SCE RI-IST Program including section 4.3.3 of Regulatory Guide 1.175; the performance history supports the inspection interval extension. The IDP also monitors the performance history to ensure the judgement to extend the interval does not adversely impact valve performance.

SCE will develop and proceduralize a schema to determine an MOV test interval that is based on IDP final risk ranking, available valve margin, and valve performance history. The schema will be comprised of an evaluation of risk ranking, relative margin, and group as well as individual valve performance.

The result of the evaluation determines the testing interval with the most frequent testing interval applied to high risk, low margin valves with poor or questionable performance history. Stepwise increases in interval out to the maximum l

allowable interval depend on the combination of risk rank, margin, and i

performance history.

f l

cr Enclosuro 1 l

RI-IST and GL 96-05 Page 4 of 6 i

NRC Question 4 1

In Question 13, the staff requested the licensee to describe the process that the li-nsee will follow for determining test intervals until sufficient plant specific test

d. a are accumulated. On pages 7 and 8 of enclosure 3 to the RAI response; tne licensee indicates that MOVs classified as L-H and LSSC will be assigned initial test intervals of 6 years. The licensee does not describe its process for selecting this test interval including its assumed degradation rate.

SCE Response:

The initial 6-year interval is consistent with GL 89-10 (reference 5) and GL 96-05 (reference 3) commitments and represents no relaxation from the approved intervals for diagnostic testing. While these referenced generic letters did not mandate a stagger test model for diagnostic testing, SCE's proposed RI-IST program relies on the application of an even stagger testing model over the respective test interval. This represents a fundamental improvement in the ability to predict degradation over the test interval for a given valve grouping.

Additionally, for the majority of valves, diagnostic test results to date indicate no significant degradation occurs over a 6-year interval. As stated in the Program Description, the 6 year interval is a maximum and not necessarily applicable to

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all valves. Valves with reduced margin or degradation rates larger than expected j

will be subject to more frequent testing.

j NRC Question 5 On pages 7 and 8 of Enclosure 3 to the RAI response, the licensee states that i

the testing of L-H and LSSC MOVs (Active) will be conducted according to OMN-1 at an initial interval not to exceed 6 years and that passive MOVs will be tested to the code of record on a frequency not to exceed 6 years. The licensee should j

describe its consideration of the provision in OMN-1 that MOVs must be exercised at least every refueling outage to ensure proper internal lubrication for j

L-H and LSSC active and passive MOVs.

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i RI-IST and GL 96-05 Page 5 of 6 SCE Response:

Code Case OMN-1 requires the refueling outage exercise. Elimination of the refueling outage exercise from passive MOVs was not intentional. MOVE will be exercised on a refueling interval basis. The refueling outage exercise is incorporated in the revised Program Description -(Enclosure 3 to the same letter j

transmitting these responses).

J NRC Question 6 On page 11 of Enclosure 3 to the RAI response, the licensee lists the elements to be considered in grouping components. The RAI response does not indicate that service conditions (such as fluid temperatures and pressures) or internal design (such as stellite sliding surfaces) will be considered in grouping MOVs and other valves.

SCE Response:

The elements listed in the question above are considered in the grouping of components. We considered these parameters implicit in the parameters listed as grouping parameters. The system and application bound operating pressures and temperature.: dile features of internal design, such as basic materials and contact / sliding st.@w materials, were considered as a subset of manufacturer and style.

NRC Question 7 The licensee should discuss its basis for extending the seat leakage testing for L-H and LSSC MOVs to 6 years.

SCE Response:

The 6-year interval for the seat leakage test is a product of the integrated decisionmaking process. A detailed review of the performance history, industry history of similar components (where available), and consideration of the risk metrics forms the basis for the extended interval. This method is described in detail in SCE's RI-IST submittal (reference 2), the Program Description (reference 4), and in the revised Program Description (Enclosure 3 to the latter transmitting this response.

f Enclosura 1 RI-IST and GL 96-05 Page 6 of 6 NRC Question 8 i

Has the licensee developed procedures implementing for implementing OMN-1 at San Onofre?

l SCE Response:

No. However, SCE intends to incorporate the analysis and evaluation of data i

sections of OMN-1 as an additional enhancement to the current MOV program independent of the RI-IST submittal.

References:

1)

Letter from L. Raghavan (NRC) to Harold B. Ray (SCE), dated April 20, 1999,

Subject:

Request for Additional Information on the Proposed Risk-Informed Inservice Testing and GL 96-05 Programs at San Onofre Nuclear Generating Station (TAC Nos. MA4509 and MA4510) 2)

Letter from A. E. Scherer (GCE) to the Document Control Desk (NRC),

i dated December 30,1998,

Subject:

Request to implement a Risk-Informed Inservice Testing Program During the Remainder of the Second Ten-Year Interval, San Onofre Nuclear Generating Station, Units 2 and 3 3)

Generic Letter 96-05, " Periodic Verification of Design-Basis Capability of Safety-Related Motor-Operated Valves

4)

Letter from A. E. Scherer (SCE) to the Document Control Desk (NRC),

i dated June 17,1999,

Subject:

Risk-Informed inservice Testing and GL 96-05 (TAC Nos. MA4509 and MA4510), San Onofre Nuclear Generating Station, Units 2 and 3 5)

Generic Letter 89-10, " Safety-Related Motor-Operated Valve Testing and Surveillance."

I ENCLOSURE 2 The Southern California Edison Company (SCE) l Risk-Informed Inservice Testing Program Revised Section 3, implementation and Ufonitoring Program, Pages

. RIsx-INFORMED IST PROGRAM FOR SOUTHERN CAUFORNIA EolsON IMPLEMENTATION AND MONITORING PROGRAM 3

WIPLEMENTATION AND MONITORING PROGRAM 3.1 Inservice Testina Proaram Chances Testing for components in the current IST program classified as HSSCs continues per the current IST program, which meets the t9quirements of the 1989 Edition of the ASME Boiler and Pressure Vessel Code,Section XI, except where veno written relief has been granted. The SCE RI-IST evaluation process concluded that the monitoring mandated by the current IST program for all components ranked as HSSCs is adequate. Where the ASME Section XI testing is practical, HSSC ranked valves or ramps not in the current ASME Section XI IST Program Plan will be tested in accordance with OM-1 'ar safety relief valves, OM-10 for active valves and OM-6 for pumps. Where the ASME Section XI testing is not practical, alternative methods will be developed to ensure operational readiness.

Note tiat there are two distinct subgroups based on RAW ranking. Those components with a high RAW

(>2) and a low Fussell-Vesely (< 0.001) are described as L-H (low Fussell-Vesely, high RAW) while those components with a low Fussell-Vesely and a low RAW (< 2) are described as LSSCs. For simplicity, the text in this section refers to both categories as LSSCs unless the topic refers to a specific subgroup.

As modified by the testing strategy described below, components in the current IST program which are determined to be LSSC will also be tested in accordance with the ASME Code,Section XI requirements, except that the test frequency will initially be extended from quarterly (or cold shutdown / refueling as applicable) to a maximum of once every 6 years (except for the refueling water storage tank outlet check valves and the emergency sump check valves which will be extended to a maximum of 8 years) plus a 25%

margin, depending on the number of valves in the group and their design, service condition, risk insights and ranking, performance history, and any compensatory measures. The extended test frequency will be staggered up to 8 years as described in Section 3.2 below. All other Code testing methods, corrective actions, documentation, and other requirements will remain in effect. Note that a rank of LSSC is insufficient justification for removing a pump or valve from the ASME Code,Section XI IST program.

Therefore, all components tested in SCE's current IST program remain in the RI-IST program. As !s true with the current IST Program, Rl-IST program selection criteria remains fundamentally based on the component safety function as defined in the applicable Code sections.

By using PRA methods, a maximum test intenial wac determined for LSSCs. This information was provided to the Expert Panel for their consideration during compont4* categorization deliberations. During periodic reassessments, the maximum test interval will be verified or modified as dictated by the integrated decision-making process.

SCE will continue to consider other test methods, such as non-intrusive testing and disassembly / inspection.

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Rtsx-INFORMED IST PROGRAM FOR SOUTHERN CAUFORNIA EDISON IMPLEMENTATION AND MONITORING PROGRAM 3.1.1 Testing Strategy SCE's proposed RI-IST tes' ting strategy for each component group will ensure to the extent practicable that adequate component capability margin exists above that required during design basis conditions. As such, component operating characteristics will not be allowed to degrade to a point of insufficient margin before

' the next scheduled test activity. On this basis, the testing strategies were deemed acceptable.

SCE's proposed Ri-IST program identifies compo7nents that are candidates for an improved test strategy (i.e., frequency, methods, or both) as well as components for which the test strategy may be relaxed. The infortnation contained in and derived from the SONGS PRA was used to help construct the testing strategy for components. Components with high safety significance will be tested in ways that are at least as effective as the current Code-required test at detecting their risk-important failure modes and causes (e.g.,

at least as effective at detecting failure, detecting conditions that are precursors to failure, or predicting end of service life). Components categorized as L-Hs and LSSCs will generally be tested less rigorously than components categorized as HSSCs (e.g., less frequent tests).

The proposec! component IST test intervals have not been extended beyond once every 6 years (approximately 3 *efueling outages, plus a 25% margin), except for the refueling water storage tank outlet check valves and the emergency sump outlet check valves, which have not been extended beyond once every 8 years plus a 25% margin. With the exception of relief valves and check valves, IST components are scheduled to be exercised or operated at least once every refueling cycle.

Test strategies were essentially augmented by leaving them as-is for all HSSCs in the IST program and adding diagnostic methods where possible. In a number of cases, only one IST function was risk-significant; nevertheless, all component functions were conservatively maintained as HSSC although the PRA ranking indicated some of the test intervals for LSSC functions were eligible for extension.

SCE considered component design, service condition, and performance history, as well as risk insights, in establishing the technical basis for the test strategy and interval assigned to each component as illustrated by the following examples:

1.

A component was considered HSSC if the component had,in the opinion of the Expert Panel, a poor performance record. By categorizing the component as HSSC, the test strategies were left as-is and the test intervals were not extended. In the case of insufficient history (i.e., new component, either new to the program or new style), the component ranking considered PRA risk metrics, component safety function redundancy, and other relevant inputs from the Expert Panel, but for these cases the Expert Panel opted to retain the current test frequency until sufficient performance history has accumulated to justify a future test interval extension.

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2. The SONGS Expert Panel also considered the impact of service condition on component perforrnance, if the service condition had no impact on performance, the PRA results were unchanged. In a few cases, such as the two steam supply check valves to the turbine driven AFW pump (1301MU003 and 3-2 t_

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' Risk-INFORMED IST PNOGRAM FOR SOUTHERN CAUFORNIA EotsON IMPLEMENTATION AND MONITORING PROGRAM 1301MU005), the Expert Panel considered the component function critical to safety system performance. Due to severe service conditions, SCE decided to disassemble and inspect both steam supply check valves each refueling outage. Since the wear on these valves is significant, the Expert Panel decided to rank them HSSC and continue to disassemble and inspect these valves each refueling until their wear characteristics are fully resolved. Design changes to mitigate the effects of the

' service conditions are being reviewed.

SONGS has not submitthd any Technical Specification amendments in conjunction with this risk-informed -

IST program submittal; therefore, all surveillance testing required by the technical specifications will :

continue to be conducted Technical Specification surveillance testing is sometimes noted as a compensatory measure for the IST interval extensions associated with L-H and LSSC ranked components.

An' example is the subgroup relay testing which is performed semi-annually and exercises numerous LSSC -

components. Although there are other compensatory measures, such as exercising during plant scheduled activities such as circulating water system heat treatment, or periodic equipment rotation for equalizing run hours, SCE conservatively chose to use only compensatory measures with a regulatory basis (e.g.,

Technical Specification surveillances), such as the subgroup relay testing and MOV biennial strokes to support the calculation of cumulative risk.

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. Components that were the subject of a previously NRC-approved relief request are summarized in Section 2.1.2. As discussed therein, the current NRC-authorized relief (or alternative) remains appropriate and 'will continue in concert with this request. As Section 2.1.2 indicates, the two current program relief requests

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relate to pumps.- There are no current' relief requests for valves.

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. The following describes the proposed testing strategy for each group of components and is considered consistent with the existing NRC positions on component test strategies. The strategy also appears to agree with the general direction that the NRC is encouraging the ASME Code groups to take in defining test strategies for components categorized as being either high or low safety significant.

' Motor-ooerated Valves (MOVs)

MOV testing will be in accordance with commitments to NRC Generic Letter (GL) 89-10, " Safety-Related Motor-Operated Valve Testing and Surveillance," and GL 96-05, " Periodic Verification of Design-Basis Capability of Safety-Related Motor-Operated Valves." Test frequency will be in accordance with the risk categorization defined below:

HSSC Testing will be performed in accordance with Code Case OMN-1, and NRC Generic Letter 89-10 and 96-05 commitments. MOVs with a passive function will be tested per the Code of Record as defined in 10CFR50.55a. Additionally, stroke time testing willinitially continue per the current code of record at quarterly, cold shutdown, nr refueling intervals based on the practicability of testing. When sufficient data accumulates and analysis indicates extension of the current stroke may be acceptable (i.e., exercising on a refueling interval basis 3-3

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RIsx-INFORMED IST PROGRAM FOR SOUTHERN CAUFORMIA EolsON IMPLEMENTATION AND MONITORING PROGRAM pursuant to OMN-1 paragraph 3.6.3), the Integrated Decision making Process (IDP) determines the acceptability of the extension. The IDP ensures the cumulative risk measures remain consistent with the acceptance guidelines specified in the SCE RI-IST Program including section 4.3.3 of Regulatory Guide 1.175. The IDP also ensures the performance history supports the extension and monitors to ensure the judgement to extend the interval does not adversely impact co.mpenent performance.

L-H Testing will be performed in accordance with Code Case OMN-1 and NRC Generic Letter 89-10 and 96-05 commitments at an initial interval not to exceed 6 years until sufficient data exist to determine a more appropriate test frequency. MOVs with a passive function will be tested per the Code of Record, except at a test frequency not to exceed 6 years (with a 25%

margin) based on evaluation of design, service condition, performance history, and compensatory actions. Seat leakage testing,if required, will be per the Code of Record, except at a test freouency not to exceed 6 years (with a 25% margin).

l LSSC Testing will be performed in accordance with Code Case OMN-1 and NRC Generic 9tter 89-10 and 96-05 commitments. MOVs with a passive function will be tested per the

ode of Record, except at a test frequency not to exceed 6 years (with a 25% margin). Seat leakage testing will per the Code of Record, except at a test frequency not to exceed 6 years (with a 25% margin).

MOV performance will be verified in accordance with GL 96-05. The SONGS commitment for satisfying GL 96-05 is described in SCE's response to GL 96-05. Furthermore, SONGS MOV periodic verification testing will comply with the provisions of ASME Code Case OMN-1. This position is consistent with SCE's response to GL 96-05.

The motor-operated valve testing strategy described above is consistent with the guidance provided in Section 3.1 of RG1.175.

SCE will ensure procedurally that the potential benefits (such as identification of decreased thrust output and increased thrust requirements) and potential adverse affects (such as accelerated degradation due to aging or valve damage) are considered when determining the appropriate testing for each MOV.

RI-IST program and MOV trend procedures will contain guidance to ensure performance and test experiences from previous tests are evaluated to justify the periodic verification interval.

1 l

SCE will develop and proceduralize a schema to determine an MOV test interval that is based on IDP final l

risk ranking, available valve margin, and valve performance history. The schema will be comprised of an evaluation of risk ranking, relative margin, and group as well as individual valve performance.

The result of the evaluation determines the testing interval with the most frequent testing interval applied to high risk, low margin valves with poor, or questionable, performance history. Stepwise increases in interval t

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F RIsI(-INFORMED IST PROGRAM FOR SOUTHERN CAUFORNIA EolsON R

' IMPLEMENTATION AND MONITORING PROGRAM i

l out to the maximum allowable interval depend on the combination of risk rank, margin, and performanw history.

Relief Valves Testing of relief valves will continue to be conducted in accordance with the Code of record (OM-1) with no change in test interval. SCE believes that relief valve performance as a whole does not warrant interval extension. In the future, should performance history change, SCE will rank valves per the Integrated

. Decision-making Process (IDP) described in Section 2.4 and extend intervals accordingly.

Check Valves (CVs1 Check valves will be tested in accordance with the Code of Record (OM-10) with the exception that the test frequency will be in accordance with the component risk categorization defined below:

' HSSC Testing will be peiformed in accordance with the ASME Code of Record as required by 10 CFR 50.55a.

L-H Testing will be performed in accordance with the ASME Code of Record as required by 10 CFR 50.55a except based on evaluation of design, sewice condition, performance history, and compensatory actions, the test frequency may be extended not to exceed 6 years plus a 25%

margin, except for the refueling water storage tank outlet check valves and the emergency I

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-sump outlet check valves which may be extended not to exceed 8 years plus a 25% margin.

LSSC Testing will be performed in accordance with the ASME Code of Record as required by 10 CFR 50.55a except based on evaluation of design, service condition, and performance j

history, the test frequency may be extended not to exceed 6 years plus a 25% margin.

The refueling water storage tank (RWST) and emergency sump outlet check valves currently comprise 2 cross unit valve groups,1) S2(3)1204MU001 and S2(3)1204MU002, and 2) S2(3)1204MU003, and S2(3)1204MUOO4. All eight valves are 24 inch Mission Duo-Check split disk check valves. Testing is currently scheduled on a 6 year stagger test interval consisting of a disassembly, inspection, and hand stroke. Extending the test interval to B years on these 2 valve groups is reasonable given the valve history, and does not result in an interval which would allow degradation without prior detection. The results of the

inspections indicate there is little, if any, wear over the initial 15 years of operation. These inspections validate the wear predictions calculated using the CVAP wear analysis software developed by Kalsi Engineering. The process of draining the 350 feet of 24 inch header piping (-8000 gal!ons) through % inch

' drain, removing the two valves (one from each group), and hand stroking requires several days. Once the

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header is re-filled, the venting operation requires multiple start-stop cycles on each of the high pressure i

injection, low pressure injection, and containment spray pumps on the particular train, and is extremely resource intensive. In addition, there is significant dose accumulation associated with disassembly, 3-5

RISK-INFORMED IST PROGMAM FOR SOUTHERN CAUFORNIA EatsOH IMPLEMENTATION AND MONITORING PROGRAM inspection and subsequent post maintenance test activities. To support a partial flow test of the sump check valves, the sump must be cleaned, then partially filled. The partial flow activity uses a low pressure injection pump for a short duration partial flow through the check valve. Due to the limited volume available in the sump, the pump run is very short in duration and requires exclusive attention in the control room during preparation and execution.

The RWST valves are partially opened for the quarterly pump inservice tests, and the sump valves are only exercised during the course of the hand stroke. A search of the NPRDS data archives shows there are no records of failures of this valve style (Mission check valves)in this application. The recorded NPRDS failures typically pertain to seat leakage increases, but do not involve failures to close. The NPRDS events primarily concern inservice water systems which have higher service duty than refueling water storage tank and emergency sump outlet check valves. Given this fact, coupled with the above discussion, extending the test interval to 8 years on these 2 valve groups is reasonable and does not result in an interval which would allow degradation without prior detection.

HSSC, L-H, and LSSC check valves at SONGS are candidates for inclusion in the Check Valve Program (CVP) which has been developed to provide confidence that check valves will perform as designed. Station procedure (s) establish test / exam frequencies, methods, and acceptance criteria and provide performance-monitoring requirements for check valves in the CVP. Check valves in the CVP include check valves that are in the IST program, check valves identified as susceptible to unusually high wear, fatigue, or corrosion, and special valves used for personnel safety such as those in the breathing air system. The CVP includes approaches for identification of existing and incipient check valve failures using non-intrusive (e.g.,

radiography, acoustic emission (AE), magnetic flux (MF), and/or ultrasonic er Jnation (UE) testing methods) and riisassembly examination. Test data will be used (e.g., trended a appropriate) to provide ccr.fidence that check valves in the CVP will be capable of performing their intended function until the next scheduled test activi+y. Check valves may be added to or deleted from the CVP based on non-intrusive testing, disassembly examination results, component replacement, or site maintenance history. Kalsi Engineering is nearing completion on a wear trending study for all check valves in the CVP. The results of this study will be factored in to the check valve test strategy using the Integrated Decision-making Process (IDP).

CVP check valve groups are based on common characteristics (manufacturer, style, application, etc.) and the check valves in any group may have the testing staggered over an extended period (e.g., up to 6 years,

+25%) based on design, risk ranking, service condition, performance history, and compensatory actions.

Testing may be scheduled in regular intervals up to an 6-year period to ensure that all check valves in the group are tested at ! east once during the 6-year test interval and that not all components are tested at one time. Testing will be scheduled / planned such that there is no more than one cycle between tests of components ir a group. Finally, the CVP is assessed on a biennial frequency, updated as appropriate with new design And operational information, and incorporates any applicable sitt or industry lessons learned.

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RIsx-INFORMED IST PROGRAM FOR SOUTHERN CAUFORNIA EatsON IMPLEMENTATION AND MONITORING PROGRAM The check valve testing strategy described above is consistent with the guidance provided in Section 3.1 of RG1.175.

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i Air-Ooerated Valves (AOVs1 AOVs will be tested in accordance with the Code of Record (OM-1' ) with the exception that the test 0

frequency will be in accordance with the component risk categorization defined below:

HSSC Testing will be performed in accordance with the Code of Record as required by 10 CFR 50.55a.

L-H Testing will be performed in accordance with the Code of Record as required by 10 CFR 50.55a except based on evaluation of design, service condition, performance history, and I

compensatory actions, the test frequency may be extended not to exceed 6 years plus a 25%

margin. Additionally L-H AOVs will be stroked at least once during each operating cycle.

j LSSC Testing will be performed in accordance with the Code of Record as required by 10 CFR 50.55a except based on evaluation of design, service condition, and performance, the test frequency may be extended not to exceed 6 years plus a 25% margin. Additionally, LSSC l

AOVs will be stroked at least once during each operating cycle.

)

in addition, all AOVs will be exercised at least once during each operating cycle.

SCE has committed to work with the Joint Owners Group for Air Operated Valves (JOG AOV) to develop an enhanced AOV testing program similar to the MOV test program established in response to GL 89-10 and GL 96-05 (described above). The intent of this program is to specify AOV Program requirements to provide assurance that AOVs are capable of performing their intended safety-significant or risk-significant functions.

Elements of the proposed program include establishing a scope of applicability, a categorization methodology, validation of safety significant functions by performing design basis reviews, performing baseline testing, and identifying the types of periodic testing necessary to identify potential degradation in a timely manner. SCE's current testing program meets or exceeds the current JOG AOV testing requirements for components within the IST program. To date, the design basis evaluations of all AOVs have not been performed. These evaluations will check the availability capability margin versus the required design-bases conditions to ensure adequate margin does indeed exist.

The AOV program is assessed on a biennial frequency, updated as appropriate with new design and operational information, and incorporates any applicable site or industry lessons learned.

The proposed AOV testing program and planned test activities described above are consistent with the guidance providd h Sections 3.1 and 3.2 of RG1.175.

3-7

RISK-INFORMED IST PROCRAM FOR SOUTHERN CALIFORNIA EDISON

~*

IMPLEMENTATION AND MONITORING PROGRAM

' Hydraulic Valves (EM). Solenoid Valves. and Others (Manual Valves. etc.)

SCE proposes to test these valves in accordance with the Code of Record (OM-10) with the exception that the test frequency will be in accordance with the component risk categorization defined below:

HSSC Testing will be performed in accordance with the Code of Record as required by 10 CFR 50.55a.

L-H Testing will be performed in accordance with the Code of Record as required by 10 CFR 50.55a except based on evaluation of design, service condition, performance history, and compensatory actions, the test frequency may be extended not to exceed 6 years plus a 25%

margin.

LSSC Testing will be performed in accordance with the Code of Record as required by 10 CFR 50.55a except based on evaluation of design, service condition, and performance history, the test frequency may be extended not to exceed 6 years plus a 25% margin.

Hydraulic valves will be exercised at least once during each operating cycle.

The proposed testing program described above is consistent with the guidance provided in Section 3.1 of RG1.175.

Pumos Pumps will be tested in accordance with the Code of Record (OM-6) with the exception that the test frequency may be in accordance with the component risk categorization defined below:

HSSC Testing will be performed in accordance with the Code of Record as required by 10 CFR 50.55a. Additionally, Code testing will be augmented with periodic oil analysis and thermography. A motor current monitoung program is in the development stage. Once implemented, HSSC purnps will be included in the scope of that program.

L-H Testing will be performed in accordance with the Code of Record as required by 10 CFR 50.55a except based on evaluation of design, service condition, performance history and compensatory actions, the test frequency may be extended not exceed 6 years plus a 25%

margin.

LSSC Testing will be performed in accordance with the Code of Record as required by 10 CFR 50.55a except the test frequency may be extended not to exceed 6 years plus a 25%

margin.

At this point no test interval extension for pumps is planned, regardless of Expert Panel categorization as LSSCs for a few pumps in the RI-IST Program.

All pumps will receive periodic thermography of their driver, lube oil analysis, alignment checks performed 3-8

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i Risx-INFORMED IST PROGRAM FOR SOUTHERN CAUFORMIA EOtsON IMPLEMENTATION AND MONITORING PROGRAM i

following major pump maintenance (using vibration ana,ysis methods to confirm alignment), motor current testing (when the motor current testing program is implemented), vibration monitoring (required by the current Code), and flange loading checks of connected piping (note that this flange loading test is not periodic, but is performed after major maintenance / overhauls that required the disassembly of any flange in a safety-related system). Additional tests (e.g., thermography of the driver, or motor current testing ) are 28 predictive in nature and involve trending of parameters that need to be compared more frequently in order to provide meaningful results. This augmented testing program for pumps is consistent with the guidance provided in RG1.175, and provides reasonable assurance that adequate pump capacity margin exists such that pump operating characteristics over time do not degrade to a point of insufficient margin before the next scheduled test activity.

The above testing strategy is consistent with the guidance provided in Section 3.1 of RG1.175.

3.2 Proaram Imolementation implementation of SCE's RI-IST Program consists of grouping components and then staggering the testing of the group over the extended test interval for those components ranked L-H or LSSC.

3.2.1 Grouping SCE performed a rigorous grouping analysis that involved several component attributes. The results of the grouping analysis are presented in Table 3.2-1, located at the end of Section 3. The groups share the following distinct characteristics:

System Component type (MOV, AOV, Check Valve, etc.)

Manufacturer Size Style (globe, gate, swing check, tilt disk, etc.)

I Application (pump discharge, flow path, orientation, etc).

The grouping attributes selected and listed above satisfy NRC criteria provided in NUREG-1482. The required sampling techniques described in NUREG-1482/ Generic Letter 89-04, Position 2 are design, service condition, and valve orientation.

Groups have been populated and testing has been scheduled such that the entire group will be tested over i

a range of quarterly to 6 years (except for the refueling water storage tank outlet check valves and the

)

emergency sump check valves which will be extended to a maximum of 8 years) plus a 25% margin, i

" Both dnver thermography and motor current testing are currently in the early stages of implementation at SCE.

3-9

O RISK-INFORMED IS T PROGRAM FOR SOUTHERN CAUFORNIA EolsOn IMPLEMENTATION AND MONITORING PROGRAM depending on the size, safety and risk significance, and past performance of valves in the group. The population of the group proved to be dependent upon the total available population of the component, as well as consideration of the testing schedule that the program seeks to maintain.

The stagger test model allows trending and monitoring of the performance of components in the group to ensure that the selected test frequency is appropriate. Grouping components in this manner and testing on a staggered basis over the test frequency will reduce the importance of common cause failure modes, as selected components in the same staggered failure modo group are periodically tested over the group's extended test interval, ensuring that component capability will be maintained over the test interval. The sequence of testing will be repeated to ensure the maximum amount of time between testing of a component does not exceed the 6 year test interval (except for the refueling water storage tank outlet check valves and the emergency sump check valves which will not exceed an 8 year test interval) plus a 25%

margin. Finally, SCE's RI-IST Program willincorporate the expansion ciiteria described in NUREG-1482, which states that if a potentially generic problem is identified during a test, all vr ses in the group in that unit must be inspected / tested during the refueling outage.

The valve group designators are composed of the system, a sequential number and a unit identifier, as illustrated below.

Group Identifier 1204_032 YW Unit System Sequence Note:

Consistent with plant convention, components common to both units or grouped across units display a unit *0" group identifier in several cases the grouping spans two systems. In these cases, the component functions meet the grouping criteria and the system designation break is arbitrary. For example, for valve groups 1208_012 and 013, the charging system connects to the high pressure safety injection path through independent piping and manual isolation valves. The manual valves are identical in design and function, but they are arbitrarily designated as different systems (Safety injection and Charging). Hence, combining these valves as a group does not violate the grouping criteria.

In summary, the L-H or LSSC valves in any group may have the testing staggered over an extended period (e.g., up to 6-years, except for the refueling water storage tank outlet check valves and the emergency sump check valves which will be extended to a maximum of 8 years, plus 25% margin) based on design, service condition, performance history, risk ranking, compensatory actions (for L-H valves), and the number 3-10

RIsx-INFORMED IST PROGRAM FOR SOUTHERN CALIFORNIA EOISON IMPLEMENTATION AND MONITORING PROGRAM of valves in a group. Testing will be scheduled on a stagger test basis to ensure:

All valves in the group are tested at least once during the stagger test interval and, Not all components are tested at one time.

Generally, extensions for L-H and LSSC ranked components adhere to the following model (Table 3.2-1 contains the stagger test interval):

VALVES PER GROUP FINAL TEST INTERVAL 1

2yr - 2A 2 (or multiples of 2) 4yr - 4A(S) 3 (or multiples of 3) 6yr - 6A(S)

Note: The "(S)" indicates a stagger test This submittal does not change the current IST program alternate testing justifications, in that tesung previously identified as cold shutdown or refueling remains in a " test at shutdown" classification. The alternate testing justifications are available for review, if required.

The performance history of the E/H valves on the AFW pump flow path (HV4762 and HV4763)is such that this valve group did not merit an increase in test frequency. In addition, some check valves were replaced with an improved design (1201MUO19 and 1201MUO21), but since they have not yet accumulated adequate performance history, their test frequency will remain at the cold shutdown interval. When adequate performance history is obtained, these valves will be re-evaluated and the interval will be extended as appropriate.

3.3 Performance Monitorina ofIST Components in addition to the specific inservice testing proposed for each component group discussed in Section 3.1.1 above, the RI-IST program will perform the following additional monitoring for each component group. The additional performance monitoring activities listed below by component type are applicable to all components within a given group regardless ofindividual ranking (HSSC, L-H, or LSSC).

The proposed monitoring plan is sufficient to detect component degradation in a timely manner. Further, l

the monitoring activities identified for each component group ensure that the following criteria are met:

l Sufficient tests are conducted to provide meaningful data.

The inservice tests are conducted such that incipient degradation can reasonably be expected to be detected.

3-11

Risk-INFORMED IST PROGRAM FOR SOUTHERN CAUFORNIA EolSON IMPLEMENTATION AND MONITORING PROGRAM Appropriate parameters are trended to provide reasonable assurance that the component will

=

remain operable over the test interval.

The proposed performance monitoring plan is sufficient to ensure that degradation is not significant for components placed on an extended test interval, and that failure rates assumed for these components will not be significantly compromised. Tho proposed performance monitoring, when coupled with SCE's corrective action program (discussed in Section 2.4.1), ensures corrective actions are taken and timely adjustments are made to individual component test strategies where appropriate.

The SCE RI-IST Program will be reassessed at a frequency not to exceed once every other refueling outage, based on Unit 3, to reflect changes in plant configuration, component performance test results, industry experience, and other inputs to the process. Configuration changes will be assessed in concert with the current design change process. Therefore, the monitoring process for RI-IST is adequately coordinated with existing programs (e.g., Action Request program, Maintenance Rule monitoring, and design change process) for monitoring component performance and other operating experience on this site and, where appropriate, throughout the industry. Althouria the monitonng of reliability and unavailability goals for operating and standby systems / trains is required by the Maintenance Rule, it alone might not be sufficient to ensure operational readiness of components in the RI-IST program. The SONGS Action Request program requires timely operability assessment for component performance issues detected outside the auspices of the IST program. This process, coupled with the evaluations performed in Maintenance Rule space in concert 'with IST trending, ensures continued operational readiness of RI-IST components.

Motor-Overated Valves (MOVs)

Actuator electricalinspections Limit switch assemblies Torque switch assemblies Leads, jumpers, lugs, caps, tape, space heaters, environmentally qualified (EQ) wire splices and cable ties inspect terminal blocks, motor T-drains Assess motor overheating indication Perform motor megger Actuator lubrication inspection inspect for weeping, grease relief for function, grease level in main gear and clutch housing, and grease quality Add grease to stem reservoir Lubricate upper drive sleeve bearing Lubricate valve bushing via grease fitting, stem threads, and yoke legs / anti-rotation plate 3-12

O Risx-INFORMED IST PROGRAM FOR SOUTHERM CAUFORMIA EotsOM

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IMPLEMENTATION AND MONITORING PROGRAM on WKM globes inspect stem nut for tightness and staking, actuator type SB compensator spring housing for

-e cracks, and stem protective cover Valve PM activities Other activities Perform handwheel operation Visualinspection for gross irregularities, upper bearing housing cover for warping on SMB-

000, Remove springpack/ worm to inspect spring pack, worm, worm gear, torque switch roller, grease in main housing Remove motor to inspect motor pinion, worm shaft gear, declutch mechanism.

J grease in motor compartment Verify / tighten actuator mounting bolts, anti-lock rotation plat jam nuts Verify / adjust actuator stop nuts and monitor stem nut thread condition Relief Valves Test results trended New valves testeo prior to installation Valves set as close to nominal as practical Check Valves Combination of acoustic, magnetic, and/or ultrasonic testing methods are used as appropriate Data retrieved from these methods will be compared with previous results and the differences evaluated Open and close testing Check valve disassembly inspections are performed where other testing is not practicable Leak rate testing is performed by 10 CFR 50, Appendix J program Leak testing for check valve closed exercise testing where appropriate Air-Ooerated Valves (AOVs)

Static diagnostic testing performed following valve or actuator overhaul or corrective maintenance that could impact valve function or as requested Routine overhauls Disassembly, cleaning, inspection 3-13

e a

Risx-INFORMED IST PROGRAM FOR SOUTHERN CAUFORNIA EDISON IMPLEMENTATION ANO MONITORING PROGRAM Replacement of elastomers Re-assembly and testing Response time testing

. Valves exposed to extreme environmental conditions will have repetitive maintenance orders for actuator replacement Positioner PMs consist of the following:

e Removal disassembly, cleaning, inspection Parts replacement as required Reassembly and test Dynamic testing (the following testing parameters as applicable)

Bench set, maximum pneumatic pressure, seat load, spring rate, stroke time, actual travel, e

total friction Setpoint of pressure switch (s) relief valve, regulator, etc.

e Minimum pneumatic pressure to accomplish safety fur:ction of valve assembly Pneumatic pressure at appropriate point in operation Others as applicable e

Pumos.

Margin to safety limit deviations - head curves Lube oil analysis

-. Alignment checks Motor current testing (recently initiated - program still developing) e Vibration monitoring e

Flange loading checks of connected piping - (not periodic - only performed after disassembly) e Thermography (recently initiated)

. 3.4 Feedback and Correctiva Action Proaram When a component with an extended test interval fails to meet established test criteria, corrective actions will be taken in accordance with the SONGS Action Request (AR) Program (the basic initiator for the

. corrective action program) as described below for the RI-IST program.

The SONGS AR program is initiated by component failures that are detected by the IST program, as well I

3-14

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l Risx-lMFORMED IST PROGRAM FOR SOUTHERM CALIFORMIA EatsOM IMPLEMENTATION AND MONITORING PROGRAM as by other mechanisms, such as normal plant operation, or inspections. For components not meeting any acceptance criteria, an AR is generated. This document initiates the corrective action process.

For example, during a " substantial flow" pump IST, the discharge check valve is effectively tested during the course of the pump test. Since the pump test can not be considered satisfactory if the check valve fails to perform its risk significant function (i.e., open), a test failure would be recorded and an AR would be initiated. The recorded information could then be used tr. assess whether a significant change in component reliability has occurred such that the component would merit a change in test interva'.

Note, however, that the initiating AR event may be darived from causes other than an unacceptable IST test. In fact, the initiatiaq event could be any other indication that the component is in a non-conforming condikn. When an unsatisfactory condition occurs, it is evaluated to fulfill the following objectives:

(1)

Determine the impact on system operability and take appropriate action; (2)

Review the previous test data for the component and all components in the group; (3)

Perform a root cause analysis, as appropriate; (4)

Determine if the event is a generic failure. If it is a generic failure whose implications affect a group of componentr,, initiate corrective action for all components in the affected group.;

(5)

Initiate corrective action for failed IST components; and (6)

Evaluate the adequacy of the test strategy. If a change is required, review the IST test schedule and change as appropriate.

As is apparent from the AR process outlined above, the SONGS corrective action guidance and procedures achieve the following objectives:

The procedures comply with Criterion XVI, " Corrective Action" as specified by Appendix B to 10 CFR Part 50.

The procedures institute a process that determines the impact of the failure or noncoriforming condition on syc'em/ train operability. SCE refers to the appropriate Technical Specification when component capability cannet be demonstrated.

The procedures determine and correct the apparent or root cause of the failure or nonconforming condition (e.g., improve testing practices, repair or replace the component).

The procedures assess the applicability of the failure or nonconforming condition to other components in the IST program (including any test population expansion that may be required for grouped components such as relief valves).

The procedures correct other susceptible similar IST components as necessary.

The procedures consider the effectiveness of the component's test strategy (i.e., fiequency and 3-15

r RIsx-INFORMED IST PROGRAM FOR SOUTHERN CALIFORNIA EolsON IMPLEMENTAT!ON AND MONITORING PROGRAM methods) in detecting the failure or nonconforming condition. They adjust the test frequency or methods or both, as appropriate, where the component (or Group of componer6ts) experiences repeated or age-related failures or nonconforming conditions.

SCE's corrective action evaluations will periodically be given to the SONGS PRA group so that any necessary model changes and PRA component re-categorizatien will be incorporated as appropriate.

Performance history and data, including the adequacy of compensatory measures, will be fed back through thu site processes to the IST Coordinator and the RI-IST Expert Panel. In this way, any unacceptable performance will be detected early and can be factored into the program. If an ineffective test intervalis detected,it will be evaluated through the corrective action programs and resolved through appropriate changes to the IST Program.

Additionally, as part of the corrective action process, the IST Coordinator will evaluate the necessity of increasing the test frequency (i.e., decreasing the time between tests) of a component (or group of components) if the cause of failure is determined to be age-related. Furthermore, the SONGS Inservice Testing Coordination ard Trending Program procedure will be modified to require the evaluation of the effects of a component failure or degradation for common causes across other plant systems. Therefore, the RI-IST feedback and corrective action process is consistent with the acceptance guidelines contained in Section 3.4 of RG1.175.

3. 5 Periodic Reassessment As a living process, components will be reassessed at a frequency not to m ceed every other refueling outage (initiated based on Unit 3 refueling outages) to reflect changes in plant configuration, component performance test results, industry experience, and other inputs to the process. The RI-IST reassessment will be completed within 9 months of completion of the outage. Significant changes in plant configuration may require a more expe6Mnt assessment. One or more such emergant modifications resulting in significant changes in the PRA model is an example that would require a more expedient assessment.

Part of this periodic reassessment willinvolve feedback to the PRA group. This includes information such as components tested since the last reassessment, number and type of teets, number of failures, corrective actions taken including generic implication and changed test frequencies. Once the PRA has been reassessed, risk infonnation will be re-introduced to the Integrated Decision-making Process (IDP) for Expett Panel deliberation and confrmation of the existing lists of HSSCs, L-Hs, and L-LSSCs or modification of these lists based on the new data. As part of the IDP, confirmatory measures previously used to categorize components as L-Hs or LSSCs will be v31idated. Additionally, the maximum test interval will be venfied or modified as dictated by the IDP.

The rh analysk performed for the initial Risk-informed IST Program will be updated every other refueling outage. As part of the update, plant-specific performance histories will be analyzed by the PRA analysts and incorporated into the PRA models, then component importance will be recalculated. The Expert Panel 3-16

s

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RISK-INFORMED IST PROCRAM FOR SOUTHERN CAUFORNIA EDISON IMPLEMENTATION AND MONITORING PROGRAM will then review the performance histories and PRA inputs and determine if any L-Hs or LSSCs should be L

re-categorized as HSSCs because of plant-specific performance, or vice versa. This approach is considered to be both prudent and conservative, since it ensures that any new IST components will be evaluated by the RI-IST process before its ASME Code test requirements are relaxed.

For each L-H (LSSCs that have a high RAW), the Expert Panel either selected a compensatory measure or provided justification, based on model and performance considerations, wh a compensatory measure was j

f not required. Compensatory measures are tests and other activities that could be credited to reduce the increase in core darnage frequency associated with test interval changes (e.g., pump operability test or pump IST for pump discharge check valves, slave relay test for MOVs, normal instrumentation monitoring, locked valve program, subgroup relaytesting every 180 days per technical specifications) Compensatory i

measures which are used as part of the IDP process to qualitatively justify the extension of a test interval will be re-verified during the lDP process update.

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l 3-17

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ENCLOSURE 3 The Southern California Edison Company (SCE)

Risk-informed inservice Testing Program Revised Program Description

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RISK-INFORMED INSERVICE TESTING PROGRAM DESCRIPTION The proposed alternative is a risk informed process to determine the safety significance and testing strategy of components in the ASME Section XI Inservice Testing (IST) Program, and identify not;-ASME IST components (pumps & valves) modeled in the Probabilistic Risk Assessment (FRA) that are determined to be High Safety Significant Components (HSSCs).

The process consists of the following elements.

1. Categorize components by Fussell-Vesely (FV) and Risk Achievement Worth (RAW) importance measures based on the San Onofre Nuclear Generating Station (SONGS) 2/3 Living PRA. (PRA Process)

2. Blend deterministic and probabilistic data to perform a finalimportance categorization of components as either Low Safety Significant Component (LSSC), Potentially High (L-H) or High Safety Significant Component (HSSC). (integrated Decision Process - l lDP)

3. Develop / Determine Test Frequencies and Test Methodologies for the ranked components. (Testing Philosophy)

4. Evaluate cumulative risk impact of new test frequencies and test methodologies to ensure risk reduction or risk neutrality. (Cumulative Risk Impact)

5. Develop an implementation plan. (Implementation)

6. Develoo a Corrective Action p;an. (Corrective Action)

7. Perform periodic reassessments. (Periodic Reassessments) i

8. Develop a methodology for making changes to the Risk Informed - Inservice Testing l

(RI-IST) program. (Changes to RI-IST)

With these elements and their implementation, the key safety principle discussed in the Basis for Acceptance are maintained.

Page 1 of 14

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'1. PRA Process n

PRA methodolbgy facilitates determination of the risk significance of companents based on -

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end states of interest, such as core damage frequency (CDF) and release of radioactivity (e.g., large early release frequency (LERF)).

The full scope (internal and external events, and shutdown) PRA used to develop the importance measures is adequate for this application, and is complemented by the Integrated Pscision Process (l.DP). Evaluation of initiating events also includes loss of

. support systems and other special events such as Loss.of Coolant Accident (LOCA), Steam Generator Tube. Rupture (STGR), station blackout, and Anticipated Transient without Scram

~ (ATWS).

~

The PRA model used for the development of importance measures for the RI-IST was independently reviewed to ensure completeness and accuracy. Additionally, all changes to the model are formally tracked and reviewed to ensure the change is complete, accurate,

appropriately implemented in the computer model, and documented.

The PRA will be periodically updated (See Section 7) to reflect the current plant design, procedures, and programs.

2.' Component Ranking Two figures of merit will be used to initially categorize components: Fussell-Vesely (FV) and Risk Achievement Worth (RAW). For the RI-IST Program, the following criteria will be used to initially rank components for review by the Integrated Decision Process (lDP).

Category Criteria High (HSSC)

FV>0.001 Potentially High (L-H)

FV < 0.001 and RAW > 2 l

Low (LSSC)

FV<0.001 and RAW <2 These CDF and LERF thresholds ensure that the cumulative risk impact due to changes in

. test frequencies are within the acceptance guidelines of Regulatory Guides 1.174.

I Methodology / Decision Criteria for PRA

The fol' lowing describes a methodology that may be used to categorize components in the RialST when the program is reassessed. However, only those elements that are significantly affected by the model changes (e.g., design modifications or procedural changes) need to be reviewed in detail using this process. The scope of the review and the justification for it will be documented as part of the IDP. The following steps will be applied by the IDP:

Page 2 of 14 i

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a) Review FV and RAW importance measures for pumps and valves considered in the PRA against the classification criteria.

b) Review component importance measures to ensure that their bases are well understood and are consistent with the SONGS specific levels of redundancy, diversity, and reliability.

PRA Limitations a) Address the sensitivity of the results to common cause failures (CCF), assuming all/none of the CCF importance is assigned to the associated component.

b) Evaluate the sensitivity due to human action modeling. Identify / evaluate proceduralized operator recovery actions omitted by the PRA that can reduce the ranking of a component.

c) Consider industry history for particuler IST components. Review such sources as NRC Generic Letters, Significant Operating Event Report (SOERs), and Technical Bulletins and rank accordingly.

i d) For components with high RAW / low FV, ensure that other compensatory measures are available to maintain the reliability of the component.

e) Identify and evaluate components whose performance shows a history of causing entry into LCO conditioas. To ensure that safety margins are maintained, consider retaining the ASME test frequency for these components.

LevelII(LERF)

Consider components / systems that are potential contributors to large, early release.

Determine LERF FV and RAW for components and/or determine which would have i

the equivalent of a high FV or low FV /high RAW with respect to LERF and rank accordingly.

i IST Components Notin PRA Review scenarios involving the "not-modeled" IST components to validate that the components are in fact low risk.

l Page 3 of 14 t

High-Risk PRA Components Not in the IST Program Identify, if any, other high risk pumps and valves in the PRA that are not in the IST program but should be tested commensurate with their

{

importance.

Determine whether current plant testing is commensurate with the importance of these valves. If not, determine what test, e.g., the IST test, would be the most appropriate Other Considerations Review the PRA to determine that sensitivity studies for cumulative effects and defense in depth have been adequately addressed in the determination of component importance factors.

3. Integrated Decision Process The purpose of using the Integrated Decision Process (lDP) is to confirm or adjust the initial risk ranking developed from the PRA results, and to provide a qualitative assessment based on engineering judgement and expert experience. This qualitative assessment compensates for limitations of the PRA, including cases where adequate quantitative data is not available.

The IDP uses deterministic insights, engineering judgement, experience, and regulatory requirements as described above in Section 2. The IDP will review the initial PRA risk ranking, evaluate applicable deterministic information, and determine the final safety significance categories. The IDP considerations will be documented for each individual component to allow for future repeatability and scrutiny of the categorization process.

The scope of the IDP includes both categorization and application. The IDP is to provide deterministic insights that might influence categorization. The IDP will identify components whose performance justifies a higher categorization.

The IDP will determine appropriate changes to testing strategies. The IDP will identify compensatory measures for potentially high safety significant components, j

or justify the final categorization. The IDP will also concur on the test interval for components categorized as a Low Safety Significant Component (LSSC).

The end product of the IDP will be components categorized as LSSC, Potentially High Safety Significant (L-H) or High Safety Significant Component (HSSC).

Page 4 of 14

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in making these determinations, the Integrated Decision Process (IDP) ensures that key safety principles (namely defense-in-depth and safety margins), are maintained.

It also ensures the changes in risk for both CDF and LERF are acceptable per the guidelines discussed in Section 2 above. The key safety principles are described below.

Defense in Depth The SONGS RI-IST program ensures consistent defense in depth by maintaining strict adherence to seven objectives of the defense in depth philosophy described in Regulatory Guides 1.174 and 1.175. The review and documentation of these objectives are an integral feature of the IDP for future changes to the program.

Those objectives are:

1) A reasonable balance is preserved among prevention of core damage, prevention of containment failure, and consequence mitigation. Multiple risk metrics, including core damage frequency (CDF) and large early release frequency (LERF), will be used to ensure reasonable balance between risk end states (Objective 1).

2) No changes to the plant design or operations procedures will be made as part of the RI-IST program which either significantly reduces defense-in-depth, barrier independence or places strong reliance on any particular plant feature, human action, or programmatic activity (Objective 2, 5).

3) The methodology for component categorization, namely the selection of

-importance measures and how they are applied and understanding the basic reasons why components are categorized HSSC or LSSC, will be reviewed to ensure that redundancy and diversity are preserved as the more important principles. Component reliability can be used to categorize a component LSSC only when:

1) plant performance has been good, and 2) a compensatory measure or feedback mechanism is available to ensure adverse trends in equipment performance can be detected in a timely manner.

A review will ensure that test frequency relaxation in the RI-IST program occurs only when the level of redundancy or diversity in the plant design or operation i

supports it. In this regard, all components that have significant contributions to common cause failure will be reviewed to avoid relaxation of requirements on those components with the lowest level of diversity within the system (Objective 3, 4) i Page 5 of 14

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I 4)' Defenses against human errors are preserved by performing sensitivity studies.

- Sensitivity studies will be performed for human actions to ensure that components which mitigate the spectrum of accidents are not ranked low solely because of the reliability of a human action (Objective 6).

5) The intent of the General Design Criteria in 10CFRPart 50, Appendix A will be maintained (Objective 7).

Other Considerations Related To Defense-in-Depth.

When the PRA does not explicitly model a component, function, or mode of operation, a qualitative method may be used to classify the component HSSC, L-H, l

or LSSC and to determine whether a compensatory measure is required. The qualitative method is consistent with the principles of defense in depth because it 1

preserves the distinction between those components which have high relative redundancy and those which have only high relative reliability.

j Maintain Sufficient Safety Margin The IDP will perform reviews consistent with Regulatory Guides 1.174 and 1.175 to ensure that sufficient safety margin is maintained when compared to the deterministic IST program. In performing this review, the IDP will consider such things as proposed changes to test intervals and, where appropriate, test methods. The IDP will ensure that the proposed compensatory measures, when required by the program, are effective in maintaining adequate safety margin. To enhance the safety margin, the IDP will also review PRA important components not in the current IST program for potential inclusion in the RI-IST program.

1 Categorization Guidelines

'Modeled Comoonents/ Functions For modeled components / functions with a FV >0.001 the IDP either confirms the component categorization is HSSC or a justification of conservatism in the PRA model will be developed.

For modeled components / functions with a FV <0.001, but a RAW >2.0, the component will be categorized L-H. The component may be considered l

l LSSC provided a compensatory measure exists that ensures operational I

readiness and the component's performance is acceptable. If a f

compensatory measure is not available or the component has a history of poor performance, the component will not be considered for test interval extension and will be considered for potential test method enhancement.

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+

For modeled components / functions with a FV <0.001 and a RAW <2.0, the component will be categorized as LSSC provided the component's performance has been acceptable. For those components with performance problems, a compensatory measure will be identified to ensure operational readiness or the component will be categorized as HSSC.

Non-Modeled Components / Functions For components not modeled or the safety function not modeled in the PRA, the categorization is as follows:

If the sister train is modeled then the component takes that final categorization.

If the component is implicitly modeled in the PRA, the FV and RAW are estimated and the deliberation is as discussed for modeled components / functions.

If the t.u;,.ponent is not implicitly modeled, the component performance history will be reviewed. For acceptable performance history the component will be categorized as LSSC. For poor performance history, a compensatory measyre will be identified to ensure operational readiness and the compur.t categorized as LSSC, or if no compensatory measures are available, categorize the component as HSSC.

Documentation Documentation of the IDP will be available for review at the plant site. The basis for risk ranking and component grouping will be entered in the IST data system.

4. Testing Mdlosophy hfotor Operated Valves (MOVs)

HSSC Testing will be performed in accordance with Code Case OMN-1 and NRC Generic Letter 89-10 and 96-05 commitments. MOV's with a passive function will be tested per the Code of Record as defined in 10CFR50.55a.

Additionally, stroke time testing will initially continue per the current code of record at quarterly, cold shutdown, or refueling interval based on the practicability of testing. When sufficient data accumulates and analysis indicates extension of the current stroke interval may be acceptable (i.e.,

exercising on a refueling interval basis pursuant to OMN-1 paragraph 3.6.3),

the integrated Decision making Process (IDP) determines the acceptability of the extension. The IDP ensures the cumulative risk measures remain Page 7 of 14 i

l s

consistent with the acceptance guidelines specified in the SCE RI-IST Program including section 4.3.3 of Regulatory Guide 1.175. The IDP also ensures the performance history supports the extension, and monitors to ensure the judgement to extend the interval does not adversely impact

. component performance.

L-H Testing will be performed in accordance with Code Case OMN-1 and NRC 1

Generic Letter 89-10 and 96-05 commitments at an initial interval not to exceed 6 years until sufficient data exist to determine a more appropriate test frequency. MOV's with a passive function will be tested per the Code of Record, except at a test frequency not to exceed 6 years (with a 25% margin) based on evaluation of design, sorvice condition, performance history, and compensatory actions, and exercised at least once during a refueling cycle per OMN-1, Paragraph 3.6.1. Seat leakage testing, if required, will be per the Code of record, except at a test frequency not to exceed 6 years (with a 25%

margin).

LSSC Testing will be performed in accordance with Code Case OMN-1, and NRC Generic Letter 89-10 and 96-05 commitments at an initial interval not to exceed 6 years until sufficient data exist to determine a more appropriate test frequency. MOV's with a passive function will be tested per the Code of Record, except at a test frequency not to exceed 6 years (with a 25% margin),

and exercised at least once during a refueling cycle per OMN-1, Paragraph 3.6.12. Seat leakage testing, if required, will be per the Code of record, except at a test frequency not to exceed 6 years (with a 25% margin).

SCE will ensure procedurally that the potential benefits (such as identification of decreased thrust output and increased thrust requirements) and potential adverse affects (such as accelerated degradation due to aging or valve damage) are considered when determining the appropriate testing for each MOV.

RI-IST program and MOV trend procedures will contain guidance to ensure performance and test experience from previous tests are evaluated to justify the periodic verification interval.

SCE will develop and proceduralize a schema to determine an MOV test interval that is based on IDP final risk ranking, available valve margin, and valve performance history. The schema will be comprised of an evaluation of risk ranking, relative margin, and group as well as individual valve performance.

The result of the evaluation determines the testing interval with the most frequent testing interval applied to high risk, low margin valves with poor, or questionable performance history. Stepwise increases in interval out to the maximum allowable Page 8 of 14

e o

interval depend on the combination of risk rank, margin, and performance history.

l Relief Valves Testing of relief valves will continue to be conducted in accordance with the Code of record (OM-1) with no change in test interval. The Southern California Edison Company (SCE) believes that relief valve performance as a whole does not warrant interval extension. In the future, should performance history change, SCE will rank valves per the Integrated Decision-making Process (lDP) and extend intervals accordingly. The initial testing strategy will be:

HSSC Testing will be performed in accordance with the Code of Record as defined in 10CFR50.55a.

L-H Testing will be performed in accordance with the Code of Record as defined in 10CFR50.55a.

LSSC Testing will be performed in accordance with the Code of Record as defined in 10CFR50.55a Check Valves HSSC Testing will be performed in accordance with the ASME Code of Record as defined by 10CFR50.55a.

L-H Testing will be performed in accordance with the ASME Code of Record as required by 10 CFR 50.55a except, based on evaluation of design, service condition, performance history, and compensatory actions, the test frequency may be extended not to exceed 6 years plus a 25% margin, except for the refueling water storage tank outlet check valves and the emergency sump outlet check valves which may be extended not to exceed 8 years plus a 25% margin.'

LSSC Testing will be performed in accordance with the ASME Code of Record as defined by 10CFR50.55a except at a test frequency not to exceed 6 years (with 25% margin).

In addition, the interval for exercise testing for certain check valves with Appendix J local leak rate testing requirements will be assigned consistent with Appendix J, Option 9 criteria.

Page 9 of 14

E Air Operated Valves (AOVs)

HSSC Testing will be performed in accordance with the Code of Record as defined by 10CFR50.55a.

L-H

. Testing will be performed in accordance with the Code of Record as required by 10CFR50.55a except based on evaluation of design, service condition, l

performance history, and compensatory actions, the test frequency may be extended not to exceed 6 years plus a 25% margin. Additionally L-H AOVs will be stroked at least once during each operating cycle.

]

LSSC Testing will be performed in accordance with the Code of Record as defined by 10CFR50.55a except with a test frequency not to exceed 6 years (with 25% margin). Additionally, LSSC AOVs will be stroked once during the operating cycle.

Note: Currently certain AOVs are tested using diagnostic equipment. SONGS is participating in a Joint Owners Group offort to develop an AOV program similar to the MOV Program mandated by GL 89-10 and 96-05. This program will evaluate the valve / operator characteristics / capabilities and the design conditions under which the valve is expected to operate. Once this information is developed it will be evaluated and implemented as appropriate.

Hydraulic Valves (WH), Solenoid Valves, and Others (Manual Valves, etc.)

SCE proposes to test these valves in accordance with the Code of Record (OM-10) with the exception that the test frequency will be in accordance with the component risk categorization defined below:

1 HSSC Testing will be performed in accordance with the Code of Record as required by 10CFR50.55a.

L-H Testing will be performed in accordance with the Code of Record as required by 10 CFR 50.55a except based on evaluation of design, service condition, performance history, and compensatory actions, the test frequency may be extended not to exceed 6 years plus a 25% margin.

LSSC ' Testing will be performed in accordance with the Code of Record as required i

by 10 CFR 50.55a except based on evaluation of design, service condition, L

and performance history, the test frequency may be extended not to exceed 6 years plus a 25% margin.

L Page 10 of 14 L

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p:

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Pumps i

Pumps will be tested in accordance with the Code of Record (OM-6) with the exception that the test frequency may be in acco' dance with the component risk

. categorization defined below:

)

)

HSSC ' Testing will be performed in accordance with the Code of Record as required by 10 CFR 50.55a.. Additionally, Code testing will be augmented with periodic oil analysis and thermography. A motor current monitoring program I

is in the development stage. Once implemented, HSSC pumps will be

' included in the scope of that program.

L-H Testing will be performed in accordance with the Code of Record as required by 10 CFR 50.55a except based on evaluation of design, service condition, performance history, and compensatory actions, the test frequency may be extended not exceed 6 years plus a 25% margin.

LSSC Testing will be performed in accordance with the Code of Record as required by 10 CFR 50.55a except the test frequency may be extended not to exceed l

6 years plus a 25% margin.

5. Implementation-Implementation of the RI-IST to LSSC (including L-H) will consist of grouping components and then staggering the testing of the group over the test frequency.

Grouping:

Components will generally be grouped based on:

System Component type (MOV, AOV, Check Valve, etc.)

e Manufacturer

. Size Style (globe, gate, swing check, tilt disk, etc.)

l Application (pump discharge, flow path, orientation, etc).

l The population of the group will be dependent on:

total population available i

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maintaining current testing schedule Grouping components in this manner and testing on a staggered basis over the test interval reduces the importance of common cause failure modes since at least one valve in the group is tested during each cycle.

Testing of components within the defined group will be staggered over the test interval, typically 6 years. Testing will be scheduled on regular intervals over the test interval to ensure all components in the group are tested at least once during the interval, the same component is not tested repeatedly, while deferring others in the group, and not all components are tested at one time. The staggering allows the trending of components in the group to ensure the test frequency selected is appropriate.

Testing will be scheduled / planned such that there is no more than one cycle between tests of components in a group.

6. Corrective Action When an LSSC (including L-H) on the extended test interval fails to meet established I

test criteria, corrective actions will be taken in accordance with the SONGS corrective action program as described below for the RI-IST.

For all components not meeting the acceptance criteria, an Action Request (AR) will be generated. This document initiates the corrective action process. An AR may result from activities other than IST that identify a degradation in performance.

The initiating event could be any other indications that the component is in a non-conforming condition. The unsatisfactory condition will be evaluated to:

{

i a) Determine the impact on system operability since the previous test.

i b) Review the previous test data for the component and all components in the group.

c) Perform a root cause analysis.

d) Determine if this is a generic failure. If it is a generic failure whose implications

)

affect a group of components, initiate corrective action for all components in the j

affected group.

i e) Initiate corrective action for failed IST components.

f) Evaluate the adequacy of the test interval. If a change is required, review the IST Page 12 of 14

test schedule and change as appropriate.

The results of component testing will be provided to and reviewed by the PRA group for potential impact to a PRA model update. The PRA model will be updated as

- necessary with changes tracked and documented per the PRA Change Process Program.

For an emergn"t plant modification, any new IST component added will initially be included at th6 current Code of Record test frequency. Only after evaluation of the component through the RI-IST Program (i.e., PRA model update if applicable and IDP review) will this be considered LSSC with an extended test interval..

7. Periodic Reassessment As a living process, components will be reassessed at a frequency not to exceed every other refueling outage (based on Unit 3 refueling outages) to reflect changes in plant configuration, component performance test results, industry experience, and 3

other inputs to the process. The RI-IST reassessment will be completed within 9

{

months of completion of the outage.

Part of this periodic reassessment will be a feedback loop of information to the PRA.

This will include information such as components tested since the last reassessment, number and type of tests, number of failures, corrective actions taken including generic implication, and changed test frequencies. Once the PRA has been reassessed, the information will be brought back to the IDP for deliberation and confirmation of the existing lists of HSSCs and LCCSs or modification of these lists based on the new data, if required. As part of the IDP, confirmatory measures previously used to categorize components as LSSC as well as compensatory measures used to justify the extension of L-H components will be validated.

l Additionally, the maximum test interval will be verified or modified as dictated by the IDP.

I

8. Changes to Rl-IST Changes to the process described above (such as acceptance guidelines used for the IDP) as well as changes in test methodology issues that involve deviation from NRC endorsed Code requirements, NRC endorsed Code Case, or published NRC guidance are subject to NRC review and approval prior to implementation. Other changes using the process detailed above (such as relative ranking, risk categorization, and grouping) are subject to site procedures and the associated change process pursuant to 10CFR50.59. SONGS will periodically submit changes to the NRC for their information.

Page 13 of 14 1

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Notes:

I The refueling water storage tank (RWST) and emergency sump outlet check valves currently comprise 2 cross unit valve groups: 1) S2(3)1204MU001 and S2(3)1204MU002, and 2) S2(3)1204MU003, and S2(3)1204MU004. All eight valves I

are 24 inch Mission Duo-Check split disk check valves. Testing is currently scheduled on a 6 year staggered test interval j

consisting of a disassembly, inspection, and hand stroke. Extending the test interval to 8 years on these 2 valve groups is reasonable given the valve history, and does not result in an interval which would allow degradation without prior detection. The results of the inspections indicate there is little, if any, wear over the initial 15 years of operation. These inspections validate the wear predictions calculated using the CVAP wear analysis software developed by Kalsi Engineering. The process of draining the 350 feet of 24 inch header piping (~8000 gallons) through % inch drain, removing the two valves (one from each group), and hand stroking requires several days. Once the header is re-filled, the venting operation requires multiple start-stop cycles on each of the high pressure injection, low pressure injection, and containment spray pumps on the particular train, and is extremely resource intensive. In addition, there is significant dose accumulaiion associated with disassembly, inspection, and subsequent post maintenance test activities. To support a partial flow test of the sump check valves, the sump must be cleaned, then partially filled. The partial flow activity uses a low pressure injection pump for a short duration partial flow through the check valve. Due to the limited volume available in the sump, the pump run is very short in duration and requires exclusive attention in the control room during preparation and execution.

The RWST valves are partially opened for the quarterly pump inservice tests, and the sump valves are only e..ercised during the course of the hand stroke. A search of the Nuclear Plant Reliability Data System (NPRDS) data archives shows there are no records of failures of this valve style (Mission check valves)in this application. The recorded NPRDS l

failures typically pertain to seat leakage increases, but do not involve failures to close. The NPRDS events primarily concern inservice water systems which have higher service duty than refueling water storage tank and emergency sump outlet check valves. Given this fact, coupled with the above discussion, extending the test interval to 8 years on these 2 valve groups is reasonable and does not result in an interval which would allow degradation without prior detection.

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