ML092400149
| ML092400149 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 08/25/2009 |
| From: | Joseph Pacher Constellation Energy Group, Nine Mile Point |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| MSS-VR-02 | |
| Download: ML092400149 (13) | |
Text
P.O. Box 63 Lycoming, NY 13093 Nine Mile Point Nuclear Constellation Station Energy August 25, 2009 U. S. Nuclear Regulatory Commission Washington, DC 20555-0001 ATTENTION: Document Control Desk
SUBJECT:
Nine Mile Point Nuclear Station Unit No. 2; Docket No. 50-410 Third 10-Year Inservice Testing Program - Request for Alternative Number MSS-VR-02 Regarding Testing of Main Steam Safety Relief Valves
REFERENCE:
(a) Letter from M. G. Kowal (NRC) to K. J. Poison (NMPNS) dated December 29, 2008, Nine Mile Point Nuclear Station - Safety Evaluation of Relief Requests for the Unit No. I Fourth 10-Year and Unit No. 2 Third 10-Year Pump and Valve Inservice Testing Program (TAC Nos. MD9202 and MD9203)
Pursuant to 10 CFR 50.55a(a)(3)(ii), Nine Mile Point Nuclear Station, LLC (NMPNS) requests NRC authorization of 10 CFR 50.55a request MSS-VR-02 for use at Nine Mile Point Unit 2 (NMP2) for the third 10-year inservice testing interval. This proposed alternative involves the test interval for 14 main steam safety relief valves (SRVs).
By letter dated December 29, 2008 (Reference a), the NRC authorized 10 CFR 50.55a request MSS-VR-01 for NMP2 to increase the SRV test interval from 5 years to 3 refueling cycles (approximately 6 years).
The alternative described in request MSS-VR-02 (Attachment) would extend the test interval beyond 6 years for 14 SRVs, on a one-time basis, to allow the testing to be performed during the next refueling outage, which is scheduled to begin in April 2010. The basis for the request is that compliance with the previously authorized alternative (request MSS-VR-01) would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
NMPNS requests authorization of this proposed request for alternative by October 1, 2009 to enable continued plant operation until the April 2010 refueling outage. Without the requested authorization, preparations would need to commence to shut down the plant by October 9, 2009, at which time the first of the subject SRVs will exceed the currently authorized 3-refueling-cycle (approximately 6-year) test interval.
Document Control Desk August 25, 2009 Page 2 Should you have any questions regarding the information in this submittal, please contact T. F. Syrell, Licensing Director, at (315) 349-5219.
Very truly yours, 5125/0-)
JEP/DEV
Attachment:
Nine Mile Point Unit 2 - 10 CFR 50.55a Request Number MSS-VR-02 cc: S. J. Collins, NRC R. V. Guzman, NRC Resident Inspector, NRC
ATTACHMENT NINE MILE POINT UNIT 2 10 CFR 50.55a REQUEST NUMBER MSS-VR-02 Nine Mile Point Nuclear Station, LLC August 25, 2009
Constellation Energy Pump & Valve Inservice Testing Program Plan Nine Mile Point Nuclear Station - Unit 2 10 CFR 50.55a Request Number: MSS-VR-02 (Unit 2)
Proposed Alternative In Accordance with 10 CFR 50.55a(a)(3)(ii)
-- Hardship or Unusual Difficulty without Compensating Increase in Level of Quality or Safety --
ASME Code Comnonent(s) Affected:
The following Main Steam Safety Relief Valves (SRVs) are affected:
Component ID Class Cat. Label 2MSS*PSV120 1 C MAIN STEAM SRV 2MSS*PSV121 1 C MAIN STEAM SRV (ADS*)
2MSS*PSV122 1 C MAIN STEAM SRV 2MSS*PSV123 1 C MAIN STEAM SRV 2MSS*PSV124 1 C MAIN STEAM SRV 2MSS*PSV125 1 C MAIN STEAM SRV 2MSS*PSV126 1 C MAIN STEAM SRV (ADS) 2MSS*PSV128 1 C MAIN STEAM SRV 2MSS*PSV129 1 C MAIN STEAM SRV (ADS) 2MSS*PSV130 1 C MAIN STEAM SRV (ADS) 2MSS*PSV133 1 C MAIN STEAM SRV 2MSS*PSV134 1 C MAIN STEAM SRV (ADS) 2MSS*PSV136 1 C MAIN STEAM SRV 2MSS*PSV137 1 C MAIN STEAM SRV (ADS)
- ADS = Automatic Depressurization System ADolicable Code Edition and Addenda:
American Society of Mechanical Engineers (ASME) Operation and Maintenance (OM) Code-2004 Edition, No Addenda
Applicable Code Requirement
Nile Mile Point Unit 2 (NMP2) 10 CFR 50.55a Request Number MSS-VR-0 1, authorized by Reference 1, provides an alternative to ASME OM Code-2004, Mandatory Appendix I, paragraph 1-1320. The alternative requires that Class 1 pressure relief valves be tested at least once every three refueling cycles. A minimum of 20% of the valves from each valve group shall be tested within any 24-month interval. This 20% shall consist of valves that have not been tested during the current three cycle interval, if they exist. The test interval for any individual valve shall not exceed three refueling cycles.
Reason for Request
OM Code-2004, Section ISTC-3200, "Inservice Testing," states the inservice testing shall commence when the valves are required to be operable to fulfill their required function(s). Section ISTC-5240, "Safety and Relief Valves," directs that safety and relief valves shall meet the inservice test Page 1 of 10
Constellation Energy Pump & Valve Inservice Testing Program Plan Nine Mile Point Nuclear Station - Unit 2 10 CFR 50.55a Request Number: MSS-VR-02 (Unit 2) requirements of Mandatory Appendix I. The alternative to Mandatory Appendix I, paragraph 1-1320, in NMP2 10 CFR 50.55a Request Number MSS-VR-01, requires that the test interval for any individual Class 1 pressure relief valve shall not exceed three refueling cycles. The required testing ensures that the Main Steam SRVs will open at the pressures assumed in the safety analysis. These valves are located on the main steam lines between the reactor vessel and the inboard main steam isolation valves within the drywell.
Pursuant to 10 CFR 50.55a(a)(3)(ii), NMP2 requests a one-time relief from (modification to) the requirements of the approved alternative described in relief request MS S-VR-01 for fourteen (14) of the eighteen (18) NMP2 Main Steam SRVs. Relief is requested until the completion of refueling outage 12 (RF12) scheduled to begin in April 2010.
During a review of the NMP2 Inservice Testing Program with respect to an ASME OM Code inquiry interpretation, a discrepancy was identified relative to compliance with the 10 CFR 50.55a Request Number MSS-VR-01 maximum test interval for an individual SRV of three refueling cycles. The ASME OM Code interpretation (01-18) indicated that implementation of the test interval should be based upon a "test-to-test" duration. The historical NMP2 method has been to use an "installation-to-test" duration and to ensure that all installed Main Steam SRVs would not exceed the three refueling cycle duration (assuming a 24 month period for each of the refueling cycles). However, utilizing the "test-to-test" interpretation, the three-refueling-cycle interval has expired (assuming a 24 month period for the refueling cycle) for four currently installed Main Steam SRVs. For these four SRVs (see Table 1, valve serial numbers 160952, 160914, 160906, and 160950), the failure to complete the testing within the specified frequency has been addressed in accordance with the provisions of Technical Specification (TS) Surveillance Requirement (SR) 3.0.3. This SR allows compliance with the requirement to declare the limiting condition for operation (LCO) for the SRVs (LCO 3.4.4) not met to be delayed, from the time of discovery, up to 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> or up to the limit of the specified frequency, whichever is greater. For a delay period greater than 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, a risk evaluation must be performed and the risk impact managed in accordance with 10 CFR 50.65(a)(4). NMPNS has performed a risk evaluation and determined that delaying the next test for these four SRVs until RF12 was well below the acceptability threshold of 1E-06 for incremental conditional core damage probability (ICCDP). Thus, it is permissible to delay completion of the testing for these four SRVs until RF12 before complying with Required Actions of TS 3.4.4.
In addition to the four SRVs discussed above, the three-refueling-cycle interval will expire for ten additional Main Steam SRVs prior to the next scheduled NMP2 refueling outage (RF12). These ten SRVs are also listed in Table 1. The provisions of TS SR 3.0.3 cannot be applied to these ten SRVs since the surveillance interval has not yet been exceeded. Refueling outage 12 is the earliest opportunity to address the discrepancy without requiring NMP2 to enter a forced shutdown to perform these SRV tests.
The basis for this request is that compliance with the requirements in 10 CFR 50.55a request MSS-VR-01 would result in a hardship without a compensating increase in the level of quality or safety.
Technical Specification (TS) 3.4.4 requires that if one or more required SRVs are inoperable, actions must be taken to shut down the reactor. NMP2 is equipped with eighteen (18) SRVs, of which 16 are required. Without approval of this relief request, ten (10) SRVs will need to be declared inoperable approximately six months prior to the start of the 2010 refueling outage (when they are scheduled to be Page 2 of 10
Constellation Energy Pump & Valve Inservice Testing Program Plan Nine Mile Point Nuclear Station - Unit 2 10 CFR 50.55a Request Number: MSS-VR-02 (Unit 2) replaced) for failure to comply with TS SR 3.4.4.1. This would necessitate a forced shutdown of the unit for testing and replacement of the SRVs.
The Main Steam SRVs are located inside the drywell, a high radiation area. The estimated dose for the removal, testing, and re-installation of an SRV, including scaffolding erection/removal and insulation removal/re-installation, is estimated to be approximately 2 rem. As discussed below, six of the 18 SRVs are removed and tested during each refueling outage. If NMPS were shutdown before RF12 to perform SRV testing, at least six SRVs would need to be re-tested during RF12 to meet the requirement of request MSS-VR-01 that a minimum of 20% of the valves from each valve group be tested within any 24-month interval, and to re-establish the schedule of removing and testing six SRVs each refueling outage. Thus, an additional radiation exposure of approximately 12 rem would be realized if the proposed alternative is not authorized.
Based on the above discussion, and consistent with the guidance in NUREG-1482, Revision 1, Section 2.5, authorization of this one-time request will avoid undue hardship in the form of an unnecessary plant shutdown per TS 3.4.4 and the additional dose incurred for the replacement and testing of the SRVs.
Proposed Alternative and Basis for Use:
For the fourteen Main Steam SRVs impacted, Nine Mile Point Nuclear Station, LLC (NMPNS) proposes to extend the maximum test interval by varying amounts beyond the specified three refueling cycles (listed in Table 1) to allow testing to be performed during RF12. During RF12, NMPNS will remove and test all fourteen impacted Main Steam SRVs. The removed valves will be replaced with recently tested valves such that their "test-to-test" interval, based on their scheduled future replacement per the NMPNS testing methodology, will remain within three refueling cycles as required by authorized 10 CFR 50.55a request MSS-VR-01.
Additionally, as required by the Code, if the as-found set-pressure of any SRV is found to be > 3%
above or below the nameplate set-pressure, two additional SRVs from the same valve group will be tested. If the as-found set-pressure of any of these additional SRVs is found to be > 3% above or below the nameplate set-pressure, then all remaining SRVs of that same valve group shall be tested.
The basis for this request is as follows:
A review of the set-point testing results for the time period from initial operation to the present, which comprises 103 data points, shows that the average set-point change is 0.86%. This slight deviation is well within the requirement specified in NMP2 TS SR 3.4.4.1 that the as-left setpoint be within 1% of the nameplate, and well within the as-found Code requirement of plus or minus 3%. The testing of SRVs at NMP2 was taken over by the onsite test facility in 1997. There is no significant difference in the average change between the Wyle Labs data and the onsite test facility data. A significant number of the as-found setpoints were greater than 1% above the nameplate set pressure. However, only 11 were greater than 2% above the nameplate, and only 4 were greater than the Code tolerance of +3% for the as-found setpoint test, requiring testing of additional SRVs.
One valve as-found test was more than 3% below the nameplate set pressure. Note that there is a slight tendency toward higher as-found setpoints, but this tendency is well within both the Technical Specification and the Code requirements. The testing data indicates that set-point history has been good Page 3 of 10
Constellation Energy Pump & Valve Inservice Testing Program Plan Nine Mile Point Nuclear Station - Unit 2 10 CFR 50.55a Request Number: MSS-VR-02 (Unit 2) with only infrequent need for Code required additional testing. The SRV as-found set pressure test data for the last five NMP2 refueling outages is summarized in Table 2. Data on the five Main Steam SRV as-found set-point test failures identified above is summarized in Attachment 1 to this 10 CFR 50.55a request.
A 24-month fuel cycle has been implemented at NMP2. Each refueling outage, NMPNS removes and tests six of the eighteen Main Steam SRVs so that all valves are removed and tested every three refueling outages. Subsequent to completion of as-found testing, each SRV in the removed complement is disassembled to perform an inspection and maintenance activities, including disc and seat inspection for evidence of degradation such as leakage or misalignment. Any SRV that failed the as-found set pressure test is inspected to determine the cause. In the event the as-found test or the visual inspections indicate that spring pack degradation may be present, a set pressure load test is performed to determine the amount of friction present and hysteresis characteristics. The results of this test are evaluated by the test supervisor to identify irregularities in operation that might be indicative of subcomponent degradation. Based upon the results of the test review, a determination is made by the test supervisor to perform full or partial valve overhaul.
All adverse conditions are corrected, the disc and seats are lapped, and the valve is reassembled. Each SRV is then recertified for service through inspection and testing consistent with ASME OM Code requirements, including set pressure, seat tightness, stroke time and disc lift verifications, solenoid coil pick up/drop out, and air actuator integrity tests.
After recertification testing, the SRVs are stored near the test location for future use, maintaining class B cleanness requirements in accordance with station administrative procedures. The SRVs are stored in an area of the NMP2 Radwaste building that is fire resistant, weather-tight, well ventilated, and not subject to flooding. The Radwaste building ventilation system, described in NMP2 Updated Safety Analysis Report Section 9.4.3, provides filtered outside air to various areas of the Radwaste building.
The building temperature is maintained between 65'F and 1 10'F, in accordance with the system operating procedure. Maintaining the SRVs in a controlled environment during storage minimizes the potential for any valve degradation. Table 1 provides both the storage time (time period from the last test to the installation date) and the inservice time for the fourteen affected Main Steam SRVs.
The SRV as-found set pressure test data in Table 2 demonstrates that the current maintenance practices outlined above have been effective, and that pre-installation SRV storage in the Radwaste building has had no significant impact on SRV test results. Only one as-found setpoint test failure has been experienced during the time period encompassed by the data in Table 2. Note that testing performed on SRVs removed during these refueling outages utilized nitrogen, with a correlated set pressure. The data in Table 2 also illustrates that SRVs that have exceeded 6 years between tests have still demonstrated acceptable as-found setpoint test results.
Based on the above cited valve performance history, SRV maintenance practices and the controlled storage environment for the stored SRVs, there is continued assurance of valve operational readiness, as required by ASME OM Code-2004, Mandatory Appendix I, paragraph 1-1310(b) and request MSS-VR-01, even given the requested one-time extension of the test interval as outlined in this request.
Therefore, NMPNS has concluded that compliance with the ASME OM Code requirements would result in a hardship or unusual difficulty (in the form of an unnecessary plant shutdown per TS 3.4.4 and the Page 4 of 10
Constellation Energy Pump & Valve Inservice Testing Program Plan Nine Mile Point Nuclear Station - Unit 2 10 CFR 50.55a Request Number: MSS-VR-02 (Unit 2) additional dose incurred to replace and test the SRVs) without a compensating increase in the level of quality or safety.
Duration of Proposed Alternative:
This proposed alternative is requested until the completion of NMP2 refueling outage 12, which is currently scheduled to begin in April, 2010.
Precedents:
Similar relief requests have been approved for other plants as listed below:
- Letter from H. Chernoff (USNRC) to C. Pardee (Exelon), "Peach Bottom Atomic Power Station, Units 2 and 3 - Requests for Relief Associated with the Fourth Inservice Testing Interval (TAC Nos. MD7461 and MD7462)," dated September 3, 2008 (Relief Request Number 01A-VRR-1).
- Letter from R. Gibbs (USNRC) to C. Crane (Exelon), "Dresden Nuclear Power Station, Unit 2 -
Request for Relief from ASME OM Code 5-Year Test Interval Requirements (TAC No. MD5959),"
dated September 20, 2007 (Relief Request Number RV-02B).
References:
- 1. Letter from M. Kowal (USNRC) to K. Polson (NMPNS), "Nine Mile Point Nuclear Station - Safety Evaluation of Relief Requests for the Unit No.1 Fourth 10-Year and Unit No. 2 Third 10-Year Pump and Valve Inservice Testing Program (TAC Nos. MD9202 and MD9203)," dated December 29, 2008.
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Constellation Energy Pump & Valve Inservice Testing Program Plan Nine Mile Point Nuclear Station - Unit 2 10 CFR 50.55a Request Number: MSS-VR-02 (Unit 2)
Table 1: Currently Installed Main Steam SRVs at NMP2, Including Storage Time and Inservice Time Serial Comp ID - Date Last Storage Date Inservice Time Total Time Test-to- Requested
- Location Certification Time Installed at RF12 from Last Test Test Due Test Interval Test (Years) Shutdown to RF12 Date Extension Performed (Years) (4/2010) (Years) 160953 2MSS*PSV120 10/16/2003 2.46 4/2006- 4 6.47 10/15/2009 6 months LOOP - A RF10 160967 2MSS*PSV121 - 11/10/2003 2.39 4/2006- 4 6.40 11/9/2009 5 months LOOP - A (ADS) RF10 160952 2MSS*PSV122 - 6/22/2001 4.78 4/2006 - 4 8.79 6/21/2007 2 years LOOP - A RHFlO 10 months 160914 2MSS*PSV123 - 2/27/1998 6.10 4/2004- 6 12.10 2/26/2004 6 years LOOP - A RF09 2 months 160906 2MSS*PSV124 - 6/24/2001 2.77 4/2004 - 8.78 6/23/2007 2 years LOOP - B RF09 10 months 160950 2MSS*PSV125 - 6/25/2001 4.77 4/2006 - 4 8.78 6/24/2007 2 years LOOP - B RF10 10 months 160939 2MSS*PSV126 - 10/17/2003 4.46 4/2008- 2 6.47 10/15/2009 6 months LOOP-B (ADS) RF11 160905 2MSS*PSV127 - 4/2008 -
12/7/2005 2.32 2 4.32 12/6/2011 None LOOP - B (ADS) RF11 160903 2MSS*PSV128 10/10/2003 4.48 4/2008- 2 6.48 10/9/2009 6 months LOOP - B RF11 160904 2MSS*PSV129 - 4/2006 -
10/10/2003 2.48 4 6.48 10/9/2009 6 months LOOP - C (ADS) RF10 160976 2MSS*PSV130 -
10/14/2003 4/2004 -
0.47 6 6.47 10/13/2009 6 months LOOP - C (ADS) RF09 Page 6 of 10
Constellation Energy Pump & Valve Inservice Testing Program Plan Nine Mile Point Nuclear Station - Unit 2 10 CFR 50.55a Request Number: MSS-VR-02 (Unit 2)
Serial Comp ID - Date Last Storage Date Inservice Time Total Time Test-to- Requested
- Location Certification Time Installed at RF12 from Last Test Test Due Test Interval Test (Years) Shutdown to RF12 Date Extension Performed (Years) (4/2010) (Years) 160974 2MSS*PSV1 - 12/9/2005 2.31 4/2008- 2 4.32 12/8/2011 None LOOP - C RF11 160969 2MSS*PSV132 12/4/2007 0.33 4/2008- 2 2.33 12/2/2013 None LOOP - C RF11 160959 2MSS*PSVI33 - 10/17/2003 2.46 4/2006- 4 6.47 10/16/2009 6 months LOOP - C RF10 160955 2MSS*PSV134 - 4/2004 -
10/14/2003 0.47 6 6.47 10/13/2009 6 months LOOP - D (ADS) RF09 160936 2MSS*PSV135 - 12/5/2005 2.32 4/2008- 2 4.33 12/4/2011 None 160962 2MSS*PSV136 - 10/11/2003 0.47 4/2004- 6 6.48 10/10/2009 6 months LOOP - D RF09 160970 2MSS*PSV 137 - 4/2004 -
11/16/2003 0.38 6 6.38 11/15/2009 5 months I LOOP - D (ADS) RF09 Page 7 of 10
Constellation Energy Pump & Valve Inservice Testing Program Plan Nine Mile Point Nuclear Station - Unit 2 10 CFR 50.55a Request Number: MSS-VR-02 (Unit 2)
Table 2: Main Steam SRVs Test Results for the Last Five NMP2 Refueling Outages As Found Setpoint Correlated Correlated Correlated Time Test Set Max Set Min Set from Last Serial Setpoint Results Pressure Pressure Pressure Accept/ Test SRV Tested No. _ (psig) (psig) (psig) +3% (psig) -3% (psig) Reject (Years)
Refueling Outage 11, April 2008 2MSS*PSV126 160965 1195 1212 1215 1248 1181 Accept 6.77 2MSS*PSV127 160956 1205 1220 1224.9 1258.7 1190.9 Accept 6.79 2MSS*PSV128 160972 1165 1162 1184 1217 1151 Accept 8.42 2MSS*PSV131 160961 1175 1200 1194 1227 1161 Accept 6.77 2MSS*PSV132 160915 1185 1182 1205 1238 1171.4 Accept 6.77 2MSS*PSVI35 160964 1195 1197 1215 1248 1181 Accept 10.1 Refueling Outage 10, April 2006 2MSS*PSV120 160935 1185 1203 1205 1238 1171 Accept 6.44 2MSS*PSV121 160966 1195 1224 1215 1248 1181 Accept 6.40 2MSS*PSV122 160951 1185 1222 1204 1238 1171 Accept 8.11 2MSS*PSV125 160968 1185 1194 1205 1238 1171 Accept 8.12 2MSS*PSV129 160971 1205 1225 1225 1258 1191 Accept 6.42 2MSS*PSV133 160958 1165 1176 1184 1217 1151 Accept 4.78 Refueling Outage 9, April 2004 2MSS*PSV123 160960 1175 1191 1195.2 1228 1162 Accept 7.19 2MSS*PSV124 160974 1175 1193 1195.2 1228 1162 Accept 4.43 2MSS*PSV130 160936 1195 1193 1215.5 1249 1181 Accept 7.21 2MSS*PSVI34 160954 1205 1225 1225 1259 1191.6 Accept 7.92 2MSS*PSV136 160973 1175 1189 1195.2 1228 1162 Accept 6.11 2MSS*PSV137 160905 1205 1239 1225.7 1259.7 1191.6 Accept 6.12 Refueling Outage 8, March 2002 2MSS*PSV121 160939 1195 1219 1214 1248 1180 Accept 4.09 2MSS*PSVI26 160967 1195 1189 1214 1247 1180 Accept 5.88 2MSS*PSV127 160955 1205 1201 1224 1258 1190 Accept 5.90 2MSS*PSV128 160903 1165 1176 1184 1216 1151 Accept 4.08 2MSS*PSV129 160904 1205 1220 1224 1258 1190 Accept 4.08 2MSS*PSVI32 160953 1185 1181 1204 1237 1171 Accept 5.16 2MSS*PSV134 160970 1205 1192 1224 1258 1190 Accept 5.18 2MSS*PSVI35(l) 160976 1195 1170 1214 1247 1180 Reject 5.16 2MSS*PSV131(1) 160962 1175 1186 1194 1227 1161 Accept 5.17 2MSS*PSV133(') 160959 1165 1169 1184 1216 1151 Accept 5.18 Refueling Outage 7, March 2000 2MSS*PSV120 160915 1185 1219 1204 1238 1171 Accept 3.90 2MSS*PSVl21 160965 1195 1231 1215 1248 1181 Accept 3.90 2MSS*PSV122 160950 1185 1222 1204 1238 1171 Accept 3.94 2MSS*PSV123 160963 1175 1208 1194 1227 1161 Accept 3.92 2MSS*PSV124 160906 1175 1189 1194 1227 1161 Accept 3.92 Page 8 of 10
Constellation Energy Pump & Valve Inservice Testing Program Plan Nine Mile Point Nuclear Station - Unit 2 10 CFR 50.55a Request Number: MSS-VR-02 (Unit 2)
Table 2: Main Steam SRVs Test Results for the Last Five NMP2 Refueling Outages As Found Setpoint Correlated Correlated Correlated Time Test Set Max Set Min Set from Last Serial Setpoint Results Pressure Pressure Pressure Accept/ Test SRV Tested No. (psig) (psig) (psig) +3% (psig) -3% (psig) Reject (Years) 2MSS*PSVI25 160952 1185 1220 1204 1238 1171 Accept 3.90 2MSS*PSV128 160958 1165 1193 1184 1217 1151 Accept 3.94 2MSS*PSV129 160956 1205 1214 1225 1258 1191 Accept 3.16 2MSS*PSV135 160975 1195 1244 1215 1248 1181 Accept 3.88 2MSS*PSV136 160961 1175 1221 1194 1227 1161 Accept 3.93 2MSS*PSV137 160954 1205 1222 1225 1259 1191 Accept 3.88 Note: (1) SRV 2MSS*PSV135 (SN 160976) failed the as-found set pressure test (relieved early) during Refueling Outage 8. Two additional valves (2MSS*PSV131 (SN 160962) and 2MSS*PSV133 (SN 160959)) were tested per Code requirements, and both passed.
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Constellation Energy Pump & Valve Inservice Testing Program Plan Nine Mile Point Nuclear Station - Unit 2 10 CFR 50.55a Request Number: MSS-VR-02 (Unit 2)
Attachment 1: Summary of As-Found Set-Point Failures Since Initial Operation The data for the five failed Main Steam SRV as-found set-point tests (i.e., the Code tolerance of +/-3%
was exceeded) is summarized below:
- One SRV as-found set-point test failed on the low side (set-point less than the -3% tolerance). The following summarizes the test data for this SRV:
SRV Tested Serial Set When Test Test Correlated Max Set Min Set No. Point Tested Results Medium Set Pressure Pressure (psig) (psig) Pressure +3% -3% (psig)
(psig) (psig) 2MSS*PSV135(l) 160976 1195 Mar-02 1170 Nitrogen 1214 1247 1180 Note: (1) The cause for this failure was determined to be set-point drift. Minor adjustments were made to restore the set pressure to the acceptance range. No additional causes for the set-point drift were found during valve maintenance. The valve was refurbished and re-certified.
Four SRV as-found set-point tests failed on the high side (set-point greater than the +3% tolerance).
The following summarizes the test data for these SRVs:
SRV Tested Serial Set When Test Test Correlated Max Set Min Set No. Point Tested Results Medium Set Pressure Pressure -
(psig) (psig) Pressure +3% 3% (psig)
(psig) (psig) 2MSS*PSV122(") 160969 1185 Oct-90 1228 Steam n/a 1221 1149 2MSS*PSV121(Z) 160966 1195 Apr-92 1234 Steam n/a 1230.8 1159.1 2MSS*PSV123( 3) 160960 1175 Oct-96 1219 Steam n/a 1210.2 1139.7 2MSS*PSV125(3) 160953 1185 Oct-96 1228 Steam n/a 1220 1149 Notes: (1) The cause for this failure was attributed to corrosion-induced frictional forces in the close tolerance kinematic parts. The valve was refurbished and re-certified.
(2) The cause for this failure was determined to be set-point drift most likely caused by corrosion of the set point spring kinematic part surfaces subject to relative motion. The valve was refurbished and re-certified.
(3) The cause for this failure was attributed to be use of a cleaning agent by the third-party test facility that was applied prior to as-found testing to reduce inlet nozzle contamination levels. The valves were refurbished and re-certified. The SRV test procedure was revised to assure that cleaning agents are not introduced into the SRV inlet during performance of as-found testing.
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