PLA-6595, Proposed One Time Relief Request to Extend the Test Frequency for Main Steam Safety Relief Valves for Third 10-Year Interval In-Service Testing Program Plan
| ML100501162 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 02/08/2010 |
| From: | Rausch T Susquehanna |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| PLA-6595 | |
| Download: ML100501162 (17) | |
Text
Timothy S. Rausch Sr. Vice President & Chief Nuclear Officer PPL Susquehanna, LLC 769 Salem Boulevard Berwick, PA 18603 Tel. 570.542.3445 Fax 570.542.1504 tsrausch@pplweb.com Im a I
4 FEB 08 2010 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Station OP 1 -17 Washington, DC 20555 SUSQUEHANNA STEAM ELECTRIC STATION PROPOSED ONE TIME RELIEF REQUEST TO EXTEND THE TEST FREQUENCY FOR MAIN STEAM SAFETY RELIEF VALVES FOR THIRD 10-YEAR INTERVAL IN-SERVICE TESTING PROGRAM PLAN FOR SUSQUEHANNA SES UNIT 2 PLA-6595 Docket No. 50-388 Pursuant to 1 OCFR50.55a(a)(3)(i) PPL Susquehanna, LLC (PPL) requests NRC approval of Relief Request RR-07 to the Susquehanna SES Unit 2 In-Service Testing Program Plan. This Relief Request is an alternative for already approved Relief Request RR-02.
Relief Request RR-07 would extend the test interval for certain Main Steam Safety Relief Valves (SRVs) beyond 6 years for five SRVs on a one-time basis to allow the testing to be performed during the Spring 2011 refueling outage. The basis for the request is that the proposed alternative provides an acceptable level of quality and safety.
PPL requests approval of this proposed relief request by July 1, 2010.
Should you have any questions, please contact Cornelius T. Coddington at (610) 774-4019.
Sincerely, T. S. Rausch
-Ac-"?.7 Document Control Desk PLA-6595 - Revision 0 to Relief Request RR-07 Copy:
NRC Region I Mr. P. W. Finney, NRC Resident Inspector Mr. R. R. Janati, DEP/BRP Mr. A. Patel, NRC Sr. Resident Inspector Mr. B. K. Vaidya, NRC Project Manager
ENCLOSURE 1 TO PLA-6595 REVISION 0 TO RELIEF REQUEST RR-07 to PLA-6595 Page 1 of 14 RELIEF REQUEST RR-07 Relief in accordance with 1 OCFR50.55a(a)(3)(i)
Acceptable Level of Quality and Safety ASME Code Component(s) Affected:
Serial Number/
Class Category Label Component ID N63790-00-0086/
1 C
MAIN STEAM SRV PSV241F013A N63790-00-0084/
1 C
MAIN STEAM SRV PSV241F013E N63790-00-0092/
1 C
MAIN STEAM SRV PSV241F013J (ADS)
N63790-00-0094/
1 C
MAIN STEAM SRV PSV241F013M (ADS)
N63790-00-0090/
1 C
MAIN STEAM SRV PSV241F013P I
These valves are Main Steam Safety/Relief Valves. They provide overpressure protection for the reactor coolant pressure boundary to prevent failure of the reactor vessel pressure boundary that could result in unacceptable radioactive release and exposure to plant personnel. Two of these five valves are associated with the Automatic Depressurization System (ADS).
- 2.
Applicable Code Requirement
PPL Susquehanna, LLC (PPL) Relief Request RR-02, authorized by Reference 1, provides an alternative to ASME OM Code 1998 Edition through OMb-2000 Addenda, paragraph 1-1330, "Test Frequencies, Class 1 Pressure Relief Valves." The alternative requires that Class 1 pressure relief valves be tested at least once every three refueling cycles. It also requires a minimum of 20% of the valves from each valve group to 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.
- 3.
Basis for Relief:
OM Code-1998, Appendix I, 1-1300, "Inservice Testing," states the inservice testing shall commence when the valves are required to be operable to fulfill their required function(s). Paragraph 1-1330(a), "Test Frequencies, Class 1 Pressure Relief Valves," states that Class 1 pressure relief valves shall be tested at least once every 5 years, starting with initial electric power generation. The alternative to Paragraph 1-1330(a), in PPL's Relief Request RR-02, 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 to PLA-6595 Page 2 of 14 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)(i), PPL requests a one-time relief from (modification to) the requirements of the approved alternative described in Relief Request RR-02 for five (5) of the sixteen (16) Main Steam SRVs. Relief is requested until completion of the Spring 2011 refueling outage.
During a review of the industry operating experience, a discrepancy was identified relative to compliance with the 10 CFR 50.55a Relief Request RR-02 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 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 will expire for five Main Steam SRVs (Serial Numbers N63790-00-0086, N63790-00-0084, N63790-00-0092, N63790-00-0094 and N63790-00-0090) prior to the next scheduled refueling outage in Spring 2011. These five SRVs are also listed in Table 1. The provisions of TS SR 3.0.3 cannot be applied to these five SRVs since the surveillance interval has not yet been exceeded. The Spring 2011 refueling outage is the earliest opportunity to address the discrepancy without requiring Susquehanna SES Unit 2 to enter a forced shutdown to perform these SRV tests.
The basis for this request is that compliance with the requirements in Relief Request RR-02 would result in a hardship without a compensating increase in the level of quality or safety. Technical Specification (TS) 3.4.3 requires that if one or more required SRVs are inoperable, actions must be taken to shut down the reactor.
Susquehanna SES is equipped with sixteen (16) SRVs, of which 14 are required.
Without approval of this relief request, five (5) SRVs will need to be declared inoperable prior to the start of the 2011 refueling outage (when they are scheduled to be replaced) for failure to comply with TS SR 3.4.3.1. 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 in a high radiation area. The additional dose for the removal, testing, and re-installation of an SRV, including scaffolding erection/removal and insulation removal/re-installation, would be incurred. If Susquehanna Unit 2 were shutdown before the Spring 2011 refueling outage to perform SRV testing, an additional six SRVs would need to be tested during the refueling outage to meet the requirement of Relief Request RR-02. Thus, additional radiation exposure 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 3.4.3 and will avoid the additional dose incurred for the replacement and testing of the SRVs.
to PLA-6595 Page 3 of 14
- 4.
Proposed Alternative and Basis for Use:
For the five Main Steam SRVs impacted, PPL Susquehanna, LLC (PPL) proposes to extend the maximum test interval by varying amounts beyond the six year frequency interval as measured from the specified "Last Tested Date (listed in Table 1) to allow testing to be performed during the Spring 2011 refueling outage. During the Spring 2011 refueling outage, PPL will remove and test all five impacted Main Steam SRVs.
The removed valves will be replaced with recently tested valves.
Additionally, as required by the Code, if the as-found set-pressure of any SRV is found to be > 3% above 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 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 setpoint testing results for the time period from initial operation of both Unit 1 and Unit 2 to the present, which comprises 284 data points, shows that the average setpoint change is -0.79%. This slight deviation is well within the requirement specified in TS SR 3.4.3.1 that the as-left setpoint be within plus or minus 1% of the nameplate, and well within the as-found Code requirement of plus or minus 3%. The number of as-found setpoints greater than 1% above the nameplate set pressure was 34. Ten (10) were greater than 2% above the nameplate. Two (2) were greater than the Code tolerance of +3% for the as-found setpoint test, requiring testing of additional SRVs.
The testing data indicates that setpoint history has been good. Twenty (20) valves experienced as-found test results greater than 3% below the nameplate set pressure.
Only two (2) valves have experienced as-found test results greater than 3% above the nameplate set pressure. The SRV as-found set pressure test data for the last 10 years is summarized in Table 2. Data on the twenty-two (22) Main Steam SRV as-found setpoint test failures identified above is summarized in Attachment 1 to this relief request.
A 24-month fuel cycle has been implemented at Susquehanna SES Unit 2. Each refueling outage, PPL removes and tests six of the sixteen Main Steam SRVs so that all valves are removed and are 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.
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.
to PLA-6595 Page 4 of 14 After recertification testing, the SRVs are stored in controlled areas at the recertification vendor facility and at Susquehanna SES.
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 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-1998, Appendix I, paragraph I-1330(a) and Relief Request RR-02, even given the requested one-time extension of the test interval as outlined in this request. Therefore, PPL has concluded that the proposed alternative provides an acceptable level of quality and safety.
- 5.
Duration of Proposed Alternative:
This proposed alternative is requested until the completion of Susquehanna Unit 2 Spring 2011 refueling outage.
- 6.
Precedents:
Similar relief requests have been approved for Susquehanna SES and other plants are listed below:
" Letter from H. Chemoff (USNRC) to C. Pardee (Exelon), "Peach Bottom Atomic Power Station, Units 2.000 and 3 - Requests for Relief Associated with the Fourth Inservice Testing Interval (TAC Nos. MD7461 and MD7462),"
dated September 3, 2008 (Relief Request Number O1A-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).
" Letter from N. L. Salgado (USNRC) to S. Belcher (NMPNS), "Nine Mile Point Nuclear Station, Unit 2 - request for Alternative No. MSS-VR-02 Main Steam Safety Relief Valve Test Interval Extension (TAC No. ME2130)"
dated September 23, 2009.
to PLA-6595 Page 5 of 14 Letter from N. L. Salgado (USNRC) to T. S. Rausch (PPL), "Susquehanna Steam Electric Station, Unit 1 RE: Relief Requests RR-07 And RR-08 from the Requirements of the OM Code RE: Inservice Testing of Safety Relief Valves (TAC No. ME2629 and ME2888)," dated January 7, 2010.
- 7.
References:
- 1. Letter from R. Laufer (USNRC) to B. L. Shriver (PPL), "Susquehanna Steam Electric Station, Unit 1 and 2 - Third 10 Year Internal Inservice Testing (IST)
Program Plans (TAC Nos. MC3382, MC3383, MC 3384, MC3385, MC3386, MC3387, MC3388, MC3389, MC4421, MC4422)," dated March 10, 2005.
to PLA-6595 Page 6 of 14 Table 1: Currently Installed Main Steam SRVs in Susquehanna SES Unit 2 Date MSR V Design "As Left" "As Left" Safety Safety Safety Actuation Actuation Actuation Installed Valve Setpoint Setpoint Setpoint Last Serial Number (psig)
(psig)
Tested N63790-00-0086 1175 1182 08/25/2004 N63790-00-0023 1205 1199 09/22/2008 N63790-00-0028 1195 1198 07/25/2006 N63790-00-0113 1175 1181 09/24/2008 N63790-00-0084 1195 1192 08/19/2004 N63790-00-0087 1205 1204 07/27/2006 N63790-00-0082 1205 1207 12/04/2008 N63790-00-0031 1195 1195 07/24/2006 N63790-00-0092 1195 1196 08/26/2004 N63790-00-0025 1205 1204 09/27/2008 N63790-00-0021 1195 1192 12/05/2008 N63790-00-0094 1205 1210 08/30/2004 N63790-00-0081 1195 1203 07/27/2006 N63790-00-0090 1205 1203 08/19/2004 N63790-00-0089 1205 1207 07/26/2006 N63790-00-0131 1205 1204 07/28/2006 to PLA-6595 Page 7 of 14 Table 2: Main Steam SRV As-Found Test results for the Last 10 Years Set Pressure Test Deviation Serial Number Date Tested (psig)
(psig)
(psig)
% Deviation N63790-00-0019 3/30/1999 1195 1202 7
0.59 3/24/2002 1195 1185
-10
-0.84 4/22/2009 1195 1155
-40
-3.35 N63790-00-0020 3/25/2002 1205 1178
-27
-2.24 4/22/2009 1205 1165
-40
-3.32 N63790-00-0021 4/6/2001 1195 1200 5
0.42 3/21/2008 1195 1177
-18
-1.51 N63790-00-0022 4/1/1999 1205 1197
-8
-0.66 3/24/2002 1205 1199
-6
-0.50 4/29/2009 1205 1215 10 0.83 N63790-00-0023 3/30/2003 1205 1185
-20
-1.66 3/22/2008 1205 1207 2
0.17 N63790-00-0024 3/28/2003 1205 1196
-9
-0.75 N63790-00-0025 3/30/2003 1205 1169
-36
-2.99 3/21/2008 1205 1137
-68
-5.64 N63790-00-0026 3/31/2003 1195 1174
-21
-1.76 N63790-00-0027 3/24/2002 1195 1162
-33
-2.76 4/22/2009 1195 1204 9
0.75 to PLA-6595 Page 8 of 14 Set Pressure Test Deviation Serial Number Date Tested (psig)
(psig)
(psig)
% Deviation N63790-00-0028 4/6/2001 I
1195 1169
-26
-2.18 3/16/2006 1195 1190
-5
-0.42 N63790-00-0029 4/1/1999 1205 1232 27 2.24 3/26/2004 1195 1188
-7
-0.59 N63790-00-0030 4/13/2000 1195 1186
-9
-0.75 3/16/2007 1195 1190
-5
-0.42 N63790-00-0031 3/31/2003 1195 1180
-15
-1.26 3/17/2006 1195 1166
-29
-2.43 N63790-00-0032 4/6/1999 1205 1184
-21
-1.74 3/25/2004 1205 1176
-29
-2.41 N63790-00-0033 3/31/2003 1195 1190
-5
-0.42 N63790-00-0034 3/11/2005 1195 1188
-7
-0.59 N63790-00-0081 4/6/2001 1205 1190
-15
-1.24 3/15/2006 1195 1154
-41
-3.43 N63790-00-0082 3/31/2003 1205 1200
-5
-0.41 3/21/2008 1205 1159
-46
-3.82 N63790-00-0083 3/28/2003 I 1175 1161
-14
-1.19 to PLA-6595 Page 9 of 14 Set Pressure Test Deviation Serial Number Date Tested (psig)
(psig)
(psig)
% Deviation N63790-00-0084 3/28/2004 1195 1184
-11
-0.92 N63790-00-0085 4/14/2000 1175 1143
-32
-2.72 3/9/2005 1175 1195 20 1.70 4/23/2009 1175 1123
-52
-4.42 N63790-00-0086 3/29/1999 1195 1166
-29
-2.43 3/28/2004 1175 1191 16 1.36 N63790-00-0087 4/5/2001 1195 1202 7
0.59 3/17/2006 1205 1191
-14
-1.16 N63790-00-0088 4/7/2001 1205 1185
-20
-1.66 3/22/2008 1205 1205 0
0.00 N63790-00-0089 4/7/2001 1205 1185
-20
-1.66 3/16/2006 1205 1210 5
0.41 N63790-00-0090 3/27/2004 1205 1195
-10
-0.83 N63790-00-0091 3/29/2004 1205 1193
-12
-1.00 4/23/2009 1205 1187
-18
-1.49 N63790-00-0092 3/31/1999 1195 1179
-16
-1.34 3/30/2004 1195 1200 5
0.42 to PLA-6595 Page 10 of 14 Set Pressure Test Deviation Serial Number Date Tested (psig)
(psig)
(psig)
% Deviation N63790-00-0093 4/14/2000 1205 1191
-14
-1.16 3/10/2005 1205 1154
-51
-4.23 N63790-00-0094 3/30/1999 1205 1224 19 1.58 3/26/2004 1205 1174
-31
-2.57 N63790-00-0095 4/12/2000 1205 1230 25 2.07 3/11/2005 1205 1199
-6
-0.50 N63790-00-0096 4/13/2000 1205 1204
-1
-0.08 3/9/2005 1205 1194
-11
-0.91 N63790-00-0112 3/26/2002 1205 1220 15 1.24 3/15/2007 1205 1209 4
0.33 N63790-00-0113 4/6/2001 1175 1193 18 1.53 3/21/2008 1175 1164
-11
-0.94 N63790-00-0128 3/23/2002 1175 1193 18 1.53 3/15/2007 1175 1184 9
0.77 N63790-00-0129 4/12/2000 1205 1192
-13
-1.08 3/16/2007 1205 1199
-6
-0.50 N63790-00-0130 3/29/1999 1205 1208 3
0.25 3/24/2002 1205 1184
-21
-1.74 3/15/2007 1205 1145
-60
-4.98 to PLA-6595 Page 11 of 14 Set Pressure Test Deviation Serial Number Date Tested (psig)
(psig)
(psig)
% Deviation N63790-00-0131 4/4/2001 1205 1219 14 1.16 3/15/2006 1205 1215 10 0.83 N63790-00-0132 4/12/2000 1195 1154
-41
-3.43 3/10/2005 1195 1134
-61
-5.10 N63790-00-0133 3/24/2002 1195 1208 13 1.09 3/14/2007 1195 1190
-5
-0.42 to PLA-6595 Page 12 of 14 : Summary of As-Found Setpoint Failures Since Initial Operation The data for the twenty-two (22) failed Main Steam SRV as-fou'nd setpoint tests (i.e., the Code tolerance of plus or minus 3% was exceeded) is summarized below:
- Twenty (20) SRV as-found setpoint tests failed on the low side (setpoint less than the
-3% tolerance). The following summarizes the test data for these SRVs.
Set Pressure Test Deviation Serial Number Date Tested (psig)
(psig)
(psig)
% Deviation N63790-00-0019 8/21/1985 1195 1158
-37
-3.10 4/22/2009 1195 1155
-40
-3.35 N63790-00-0020 4/22/2009 1205 1165
-40
-3.32 N63790-00-0021 9/21/1996 1195 1159
-36
-3.01 N63790-00-0022 10/13/1987 1175 1136
-39
-3.32 N63790-00-0024 4/5/1995 1175 1133
-42
-3.57 N63790-00-0025 3/21/2008 1205 1137
-68
-5.64 N63790-00-0030 10/12/1987 1175 1139
-36
-3.06 N63790-00-0081 3/15/2006 1195 1154
-41
-3.43 N63790-00-0082 3/21/2008 1205 1159
-46
-3.82 N63790-00-0085 3/31/1992 1175 1109
-66
-5.62 4/23/2009 1175 1123
-52
-4.42 N63790-00-0089 1/22/1993 1185 1147
-38
-3.21 to PLA-6595 Page 13 of 14 Set Pressure Test Deviation Serial Number Date Tested (psig)
(psig)
(psig)
% Deviation N63790-00-0090 3/31/1992 1185 1143
-42
-3.54 N63790-00-0091 9/10/1986 1195 1155
-40
-3.35 N63790-00-0093 3/10/2005 1205 1154
-51
-4.23 N63790-00-0113 9/10/1987 1146 1094
-52
-4.54 N63790-00-0130 3/15/2007 1205 1145
-60
-4.98 N63790-00-0132 4/12/2000 1195 1154
-41
-3.43 3/10/2005 1195 1134
-61
-5.10 The cause of these failures was determined to be setpoint drift.
- Two (2) SRV as-found setpoint tests failed on the high side (setpoint greater than
+3% tolerance). The following summarizes the test data for these SRVs.
the Set Pressure Test Deviation Serial Number Date Tested (psig)
(psig)
(psig)
% Deviation N63790-00-0094 6/18/1991 1205 1244 39 3.24 N63790-00-0130 12/14/1990 1185 1235 50 4.22 No high side as-found setpoint test failures have occurred since flexi discs have been installed in the SRVs at Susquehanna SES.
to PLA-6595 Page 14 of 14 NOTE: Three of the five SRVs that are the subject of this relief request have never failed the Code as-found test. One SRV fail on the high side and one SRV failed on the low side.
The as-found test results for these SRVs are shown in the table below.
Set Pressure Test Deviation Serial Number Date Tested (psig)
(psig)
(psig)
% Deviation N63790-00-0084 1/15/1987 1175 1158
-17
-1.45 4/2/1991 1175 1179 4
0.34 1/22/1993 1175 1175 0
0.00 5/19/1995 1175 1189 14 1.19 3/27/1997 1195 1172
-23
-1.92 3/28/2004 1195 1184
-11
-0.92 N63790-00-0086 9/2/1986 1175 1147
-28
-2.38 3/31/1988 1175 1164
-11
-0.94 2/12/1990 1175 1166
-9
-0.77 3/31/1992 1175 1172
-3
-0.26 1/24/1994 1175 1190 15 1.28 3/29/1999 1195 1166
-29
-2.43 3/28/2004 1175 1191 16 1.36 N63790-00-0090 9/3/1986 1185 1178
-7
-0.59 2/12/1990 1185 1179
-6
-0.51 3/31/1992 1185 1143
-42
-3.54 5/9/1995 1185 1150
-35
-2.95 4/1/1997 1195 1228 33 2.76 3/27/2004 1205 1195
-10
-0.83 N63790-00-0092 11/12/1986 1195 1188
-7
-0.59 10/6/1990 1195 1176
-19
-1.59 8/17/1992 1205 1191
-14
-1.16 9/22/1996 1195 1204 9
0.75 3/31/1999 1195 1179
-16
-1.34 3/30/2004 1195 1200 5
0.42 N63790-00-0094 9/2/1986 1205 1190
-15
-1.24 3/31/1988 1205 1189
-16
-1.33 10/5/1989 1205 1177
-28
-2.32 6/18/1991 1205 1244 39 3.24 1/24/1994 1205 1178
-27
-2.24 3/30/1999 1205 1224 19 1.58 3/26/2004 1205 1174
-31
-2.57