ML20205S294
| ML20205S294 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 04/20/1999 |
| From: | Raghavan L NRC (Affiliation Not Assigned) |
| To: | Ray H SOUTHERN CALIFORNIA EDISON CO. |
| References | |
| GL-96-05, GL-96-5, TAC-M97097, TAC-M97098, TAC-MA4509, TAC-MA4510, NUDOCS 9904260171 | |
| Download: ML20205S294 (7) | |
Text
o April 20, 1999 Mr. Hirold B. Rsy Exrcutiva Vice Przsident Southern Califomia Edison Compar y San Onofre Nuclear Generating Station P. O. Box 128 San Clemente, Califomia 92674-0128
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION ON THE PROPOSED RISK-INFORMED INSERVICE TESTING AND GL 93-05 PROGRAMS AT THE SAN ONOFRE NUCLEAR GENERATING STATION (TAC NOS. MA4509, MA4510, M97097 AND M97098)
Dear Mr. Ray:
In a letter dated December 30,1998, Southem Califomia Edison (SCE) submitted a request to implement a risk-informed inservice testing (RI-IST) program during the remainder of the second 10-year interval for the San Onofre Nuclear Generating Station (SONGS). In a letter dated March 13,1997, the licensee submitted a response to the recommendations of Generic Letter
{
(GL) 96-05, " Periodic Verification of Design Basis Capability of Safety-related Motor Operated Valves." The NRC staff is reviewing the two programs together because they are interrelated, in a telephone conference call conducted with your staff on March 11,1999, the NRC staff indicated a need for additional information. To complete our review of your RI-IST and GL 96-05 programs, we request that you provide the additional information as identified in the enclosure within 60 days of the date of this letter. Your timely response to the request for additional informat'on will assist us in meeting our review schedule. This information and the schedule have hen discussed with Jack Rainsberry of your staff.
Please call Brenda Mozafari at (301) 415-2020 or me at (301) 415-1471 if you have any questions.
Sincerely, ORIG. SIGNED BY L. Raghavan, Senior Project Manager, Section 2 Project Directorate IV-2 and Decommissioning Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-361 DISTRIBUTION:
and 50-362 19diMt3 KBrockman, RIV PUBLIC LSmith, RIV
Enclosure:
Request for AdditionalInformation POlV Reading SRichards j
JZwolinski/SBlack LRaghaven
[
cc w/ encl: See next page.
EPeyton TScarbrough ACRS DFischer OGC MCheok
'Iq DOCUMENT NAME: A:W509RAl.wpd -
c To receive e copy of this document, Indicate in the box:. C" = Copy without erriobures "E" = Copy with enclosures "N"
= No copy OFFICE PDIV-2/PM PDill-3/PM MCEB/SC 6
PDIV-2/LA PDIV-2/SC t a NAME LRaghavanUL BMozafariffffDTermo R EPen M P' SDembek f. 3-DATE 04/20/99 040099 04/F/99 0461Q99 4/20 /991.4 T OFFICIAL RECORD COPY f
h ADb.
1 p
FDR
pn;tou
[
UNITED STATES S
NUCLEAR REGULATORY COMMISSION l
l WASHINGTON, D.C. 20666 4 001 April 20,1999 Mr. Harold B. Ray Executive Vice President Southern Califomia Edison Company San Onofre Nuclear Generating Station P. O. Box 128 San Clemente, California 92674-0128
SUBJECT:
REQUEST FOR ADDITIONAL iNFORMATION ON THE PROPOSED RISK-INFORMED INSERVICE TESTING AND GL 96-05 PROGRAMS AT THE SAN ONOFRE NUCLEAR GENERATING STATION (TAC NOS. MA4509, MA4510, M97097 AND M97098)
Dear Mr. Ray:
1 In a letter dated December 30,1998, Southern California Edison (SCE) submitted a request to 4
implement a risk-informed inservice testing (Rl-IST) program durin0 the remainder of the second 10-year interval for the San Onofre Nuclear Generating Station (SONGS). In a letter dated March 13,1997, SCE submitted a response to the recommendations of Generic Letter (GL) 96-05, " Periodic Verification of Design Basis Capability cf Safety-Related Motor-Operated Valves." The NRC staff is reviewing the two programs together because they are interrelated.
In a telephone conference call conducted with your staff on March 11,1999, the NRC staff indicated a need for additionalinformation. To complete our review of your RI-IST and GL 96-05 programs, we request that you provide the additional information as identified in the enclosure within 60 days of the date of this letter. Your timely response to the request for additional irformation will assist us in meeting our review schedule. This information and the schedule have been discussed with Jack Rainsberry of your staff.
Please call Brenda Mozafari at (301) 415-2020 or me at (301) 415-1471 if you have any questions.
Sincerely, L. Raghavan, Senior Project Manager, Section 2 Project Directorate IV-2 and Decommissioning Division of Licensing Project Management Office of Nuclear Reactor Regulation Docket Nos. 50-361 and 50-362
Enclosure:
Request for AdditionalInformation cc w/ encl: See next page l
i
4 San Onofre Nuclear Generating Station, Units 2 and 3 cc w/ encl:
Mr. R. W. Krieger, Vice President Resident inspector / San Onofre NPS Southern California Edison Company clo U.S. Nuclear Regulatory Con' mission San Onofre Nuclear Generating Station Post Office Box 4329 P. O. Box 128 San Clemente, California 92674 San C!emente, California 92674-0128 Mayor Chairman, Board of Supervisors City of San Clemente County of San Diego 100 Avenida Presidio 1600 Pacific Highway, Room 335 San Clemente, California 92672 San Diego, California 92101 Mr. Dwight E. Nunn, Vice President Alan R. Watts, Esq.
Southern California Edison Company Woodruff, Spradlin & Smart San Onofre Nuclear Generating Station 701 S. Parker St. No. 7000 P.O. Box 128 Orange, California 92668-4702 San Clemente, California 92674-0128 Mr. Sherwin Harris Resource Project Manager Public utilities Department City of Riverside 3900 Main Street Riverside, California 92522 Regional Administrator, Region IV U.S. Nuclear Regulatory Commission Harris Tower & Pavilion 611 Ryan Plaza Drive, Suite 400 Arlington, Texas 76011-8064 Mr. Michael Olson San Onofre Liaison San Diego Gas & Electric Company P.O. Box 1831 San Diego, California 92112-4150 Mr. S' eve Hsu Radiologic Health Branch State Department of Health Services Post Office Box 942732 Sacramento, California 94234
REQUEST FOR ADDITIONAL INFORMATiON RISK-INFORMED INSERVICE TESTING AND GL 96-05 PROGRAMS SOUTHERN CALIFORNIA EDISON COMPANY SAN ONOFRE NUCLEAR GENERATING STATION. UNITS 2 AND 3 DOCKET NOS. 50-361 AND 50-362 1.
The licensee's proposed alternative refers to establishing the frequencies based on "the methodology outlined in enclosure 2." Enclosure 2 of the December 30,1998, submittal contains a description of the methodology used to categorize components, assess overall change in risk, the expert panel process, component test strategies, implementation, and corrective action processes, etc. It also contains results. When the staff writes its safety evaluation (SE) on the San Onofre Nuclear Generating Station (SONGS) risk-informed inservice inspection (RI-IST) program it will rely on (and identify) many of the commitments made in Enclosure 2. If the licensee has a problem with the staff identifying these commitments in the SE, the licensee may want to develop a more concise RI-IST program description, more along the lines of the one submitted by TU Electric for Comanche Peak. That is, a RI-IST program description that contains the key aspects of their RI-IST program in each area.
2.
Document more clearly why normally closed manual valve S2-1305-MU476 (header supply to/from the condensate storage tank) was ranked LSSC by the expert panel, i.e.,
why the licensee preferred to add manual valve 1417-MU230 to the RI-IST program as opposed to testing S2-1305-MU476. Include manual valve 1417-MU230 in Table 3.2-1 (i.e., to be exercise-tested every refueling outage as indicated on page 2-38) or document why this alternate supply path valve should not be included in that table. It seems like components added to the licensee's RI-IST program should be included in Table 3.2-1 or in a similar but separate table.
3.
The table on page 2-47 indicates that S2-1201-MU976 and MU977 (pressurizer spray line check valves) were ranked "LSS, Test interval not extended because test historically administered incorrectly." Table 3.2-1 (page 3 of 126) indicates that the closure test on these check valves will be extended from cold shutdowns to 4AS. Similarly, the table on page 2-47 indicates that valve group 1305._052 is " Test interval is not extended. Retain LSSC ranking because these valves can be isolated by manual block valves, isolation does not affect performance of key safety function." Table 3.2-1 (page 80 of 126) indicates that the quarterly stroke test of these check valves to the closed position will be extended to 6AS. Document more clearly that while these valves will not have their test interval extended initially (as indicated in the table on page 2-47), the licensee's bounding analysis (as reflected in Table 3.2-1) will permit extending the test interval for these valves.
4.
Explain why defense-in-depth is not compromised by categorizing certain containment isolation valves (CIVs) as LSSCs (e.g., 2-1201-HV9218, 2-1902-HV7259, 2-1201-HV0509). It was not clear from the NRC staff's review of simplified system drawings
n 2-that these were supply and retum valves in closed loop systems with a higher design pressure than the containment.
5.
Describe where the evaluations of design, service condition, performance history and compensatory actions are currently documented and where they will ultimately be documented (e.g., for L-H MOVs, CVs, AOVs, HOVs; for LSSC CVs, AOVs, and HOVs)
(see pages 3-3 through 3-7).
6.
The licensee's letter dated March 13,1997, indicates that the scope of the motor-operated valve (MOV) program at SONGS in response to Generic Letter (GL) 96-05, " Periodic Verification of Design-Basis Capability of Safety Related Motor-Operated Valves," is the same as the SONGS program in response to GL 89-10,
" Safety-Related Motor-Operated Valve Testing and Surveillance." In GL 96-05, the NRC staff discusses the consideration of safety-related MOVs that are assumed to be i
capable of returning to their safety position when placed in a position that prevents their
]
safety system (or train) from performing its safety function; and the system (or train) is not declared inoperable when the MOVs are in their nonsafety position. Compare the scope of the MOV program at SONGS to the GL 96-05 recommendations.
7.
In NRC Inspection Report (IR) 50-361,362/96-10, the NRC staff closed its review of the GL 89-10 program at SONGS based on the licent,ee's actions to verify the design-basis capability of the safety-related MOVs. In the inspection report, the NRC staff noted certain long-term actions planned by the licensee. For example, the licensee planned to (1) upgrade several low-margin MOVs, (2) evaluate diagnostic test traces for MOVs 2-HV-9348 and 3-HV-9306 identified as inspector Followup item (IFI) 9610-01, (3) address new information on motor actuator output capability identified as IFl 9610-02, (4) improve quality assurance oversight of the MOV program, and (5) resolve the questions regarding the safety function of the refueling water storage tank (RWST) outlet valve discussed in IFl 9507-01. Describe the status of these long-term actions.
8.-
In its March 13,1997, letter on GL 96-05, the licensee states that motor-operated gate
+
valves with low margin (less than 20%) or an allowable valve factor less than or equal to 0.8 will be diagnostically tested under dynamic conditions at least every 3 refueling cycles. Provide the setup requirements for all GL 96-05 MOVs at SONGS. Identify the MOVs requiring periodic dynamic testing. Provide the basis for grouping MOVs to apply dynamic test data to non-dynamically tested MOVs. Provide the basis for the degradation rate for each GL 96-05 MOV.
9.
In its March 13,1997, letter on GL 96-05, the licensee states that no periodic dynamic testing is planned for globe or butterfly valves at SONGS. Provide the available margins for these MOVs, and the bases for both the margins and the assumption that no
- degradation will occur in the performance of these valves.
10.
In its March 13,1997, letter on GL 96-05, the licensee stated that periodic static diagnostic testing will be performed to monitor actuator output. In a telephone discussion on March 11,1999, the licensee indicated that it had not incorporated the recent Limitorque guidance in Technical Update 98-01 (and its Supplement 1) for
, ac-powered MOVs, but was conducting a research program to evaluate MOV output capability. Provide the basis for the assumptions in predicting the capability of ac-powered MOVs and monitoring potential performance degradation during the ongoing research effort at SONGS. Describe the research effort at SONGS to address ac-powered MOV output under design-basis conditions, including load requirements, degraded voltage, and temperature effects. Provide the status of the response to the ongoing industry evaluation of manufacturer's guidance for de-powered MOVs at SONGS, including determination of the degradation rate associated with aging effects that could result in a potential decreace in actuator output.
11.
Explain how risk insights will be applied in the GL 96-05 program at SONGS. Compare the MOV risk-ranking methodology used at SONGS to generic industry methodologies.
12.
In its RI-IST submittal, the licenseo states that the SONGS MOV periodic verification testing program will comply with the provisions of American Society of Mechanical Engineers (ASME) Code Case OMN-1, " Alternative Rules for Preservice and inservice Testing of Certain Electric Motor Operated Valve Assemblies in LWR Power Plants."
Clarify the commitment to implement ASME Code Case OMN-1 as a relief request as an alternative to MOV stroke-time testing in the ASME Code. Address the conditions on use of the code case specified in GL 96-05 and the use of risk insights to evaluate potentia! extensions if any, of exercise intervals for high-risk MOVs.
13.
In its RI-IST submittal, the licensee states that the provisions of paragraph 6.4.4, Determination of MOV Test interval, in OMN-1 will not be followed until sufficient plant-specific data are accumulated. Describe the process the licensee will follow to determine test intervals until that time 14.
In Section 2.2.1, the role of defense-in-depth is discussed. " Rule number 1" states that the level of redundancy is the principal criterion upon which classification rests. In Table 2.1-1, the term " average redundancy" is used. Explain how the application determines the level of redundancy. Define " average redundancy."
15 The Expert Panel has down-classified some components because of conservatism in the probabilistic risk assessment (PRA)(for example, pages 2-17 and A-13). The NRC staff agrees that conservatism in the PRA can result in components being classified as HSSC that are not risk significant, however, it is preferred that in these cases, the PRA be modified to remove the conservatism (see page 19-B4 of Chapter 19 of the Standard Review Plan P3RP]). This is particularly true for cases where the Expert Panel has noted discrepancies in the PRA (see the first paragraph on page A-13). PRA conseivatism or inaccuracies can mask the importance of other SSCs that are otherwise ranked as LSSC.
a.
In the calculation of cumulative risk impact, explain how the change in risk is determined for the components that were downgraded, (i.e., if unmodeled success paths accouri.sd for, or if discrepancies in the PRA accounted for, etc.)
1
.1 4
b.
In determining that the PRA was conservative (for example, by taking credit for unmodeled flow paths or unmodeled operator actions), explain the extent to which the Expert Panel considered information on availability of procedures, equipment, training, etc.
c.
If alternate success paths (not modeled in the PRA but credited in the RI-IST program were to be modeled in the risk analysis, state if components in these
{
paths would become HSSC.
d.
The December 30,1998, submittal stated that the PRA will be kept as a living document. Thus, changes to the plant design and operations can be reflected in the PRA models, and the effects of these changes can therefore be evaluated for programs such as the RI-IST program. In cases where unmodeled success paths are given credit, describe the mechanisms for ensuring that SSCs in these paths will receive similar treatment (i.e., will remain available at the level credited q
in the licensing change request).
16.
The December 30,1998, submittal documents a decrease in risk because of a decrease in the interfacing systems loss-of-coolant (ISLOCA) frequency. In the SONGS individual plant examination (IPE) submittal, the ISLOCA frequency for the low pressure safety injection (LPSI) lines was determined based on the NUREG/CR-4550 ISLOCA analysis for a pathway consisting of two check valves. The SONGS IPE then included a factor of 0.01 for the LPSI MOV. Discuss how this IPE analysis was modified to account for the change in test intervals (in the calculation of delta risk).
17.
Discuss the grouping of components in the RI IST program relative to the CCF groups used in the PRA. Identify any caces where components with different testing procedures and characteristics (e.g., test intervals) are placed in the same common cause group.
l l
I