PLA-8112, Relief Request 4RR-11 Relief from End of Interval Boundary Leakage Test PLA-8112
| ML24100A832 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 04/09/2024 |
| From: | Casulli E Susquehanna, Talen Energy |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| Shared Package | |
| ML24100A831 | List: |
| References | |
| PLA-8112 | |
| Download: ML24100A832 (1) | |
Text
Enclosure 2 Contains Security-Related Information -
Withhold in Accordance with 10 CFR 2.390
Edward Casulli Susquehanna Nuclear, LLC Site Vice President 769 Salem Boulevard Berwick, PA 18603 TALEN~
Tel. 570.542.3795 Fax 570.542.1504 Edward.Casulli@TalenEnergy.com ENERGY
April 09, 2024
Attn: Document Control Desk 10 CFR 50.55a U.S. Nuclear Regulatory Commission Washington, DC 20555-0001
SUSQUEHANNA STEAM ELECTRIC STATION RELIEF REQUEST 4RR-11 RELIEF FROM END OF INTERVAL BOUNDARY LEAKAGE TEST PLA-8112 Docket No. 50-387
In accordance with 10 CFR 50.55a(z)(2), Susquehanna Nuclear, LLC (Susquehanna), requests NRC approval of the attached relief request associated with the fourth and fifth 10-year Inservice Inspection (ISI) intervals for the Susquehanna Steam Electric Station (SSES) Unit 1.
The attached relief request, 4RR-11, is associated with the ASME Class 1 boundary leakage test required by American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code),Section XI, IWB-5222(b). Specifically, 4RR-11 requests authorization of alternative requirements for the IWB-5222(b) pressure boundary test for the volume between the inboard and outboard main steam isolation valves on the 'D' main steam line. This request will defer the pressure test between inboard and outboard main steam isolation valves on the 'D' main steam line until the next Unit 1 refuel and inspection outage (projected for spring 2026).
Since the deferred test will not be performed until the next Unit 1 refuel and inspection outage, which is in the fifth 10-year ISI interval, Susquehanna requests that the proposed alternative cover the remainder of the current fourth 10-year ISI interval and the portion of the fifth 10-year ISI interval commencing at the start of the interval (i.e., June 01, 2024) and concluding with the end of Unit 1, Cycle 24 (projected for spring 2026).
The fourth 10-year interval of the SSES ISI Program is based on the ASME Code,Section XI, 2007 Edition through the 2008 Addenda. The fourth 10-year ISI interval for Unit 1 began on June 01, 2014, and is currently scheduled to end May 31, 2024. The fifth 10-year interval of the SSES ISI Program is based on the ASME Code,Section XI, 2019 Edition. The fifth 10-year ISI interval for Unit 1 will begin on June 01, 2024, and is currently scheduled to end on May 31, 2034.
Enclosure 2 Contains Security-Related Information -
Withhold in Accordance with 10 CFR 2.390
- 2 - Document Control Desk PLA-8112 is provided to illustrate the Class 1 pressure boundary subject to the relief request.
Due to the security-related contents, Susquehanna requests that Enclosure 2 be withheld from public disclosure in accordance with 10 CPR 2.390( d)(l ).
Susquehanna requests authorization of the proposed alternative by April 12, 2024.
There are no new or revised regulatory commitments contained in this submittal.
Should you have any questions regarding this submittal, please contact Ms. Melisa Krick, Manager-Nuclear Regulatory Affairs, at (570) 542-1818.
E. Casulli
Enclosures:
- 1. Relief Request 4 RR-11
- 2. Boundary Drawing (Withhold in Accordance with 10 CFR 2.390)
Copy: NRC Region I Ms. J. England, NRC Senior Resident Inspector Ms. A. Klett, NRC Project Manager Mr. M. Shields, PA DEP/BRP Enclosure 1 to PLA-8112
Relief Request 4RR-11
Enclosure 1 to PLA-8112 Page 1 of 7
- 1. ASME Code Component(s) Affected
Unit(s) Affected: Susquehanna Steam Electric Station (SSES), Unit 1 Code Class: ASME Code,Section XI, Class 1
References:
IWB-5222(b)
Examination Categories: B-P Item Number: B15.20, Pressure Retaining Components Component Numbers: Piping between HV141F022D and HV141F028D
==
Description:==
Pressure Testing
The affected piping is highlighted in the boundary drawing in Enclosure 2.
- 2. Applicable Code Edition and Addenda
The Inservice Inspection Program for the fourth 10-year inservice inspection (ISI) interval is based on the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code),Section XI, 2007 Edition with 2008 Addenda. The fourth 10-year ISI interval began on June 01, 2014, and is currently scheduled to end on May 31, 2024. The duration of the proposed relief is through Unit 1, Cycle 24 at which point Unit 1 will be in the fifth 10-year ISI interval. The fifth 10-year ISI interval for Unit 1 will begin on June 01, 2024, and is currently scheduled to end on May 31, 2034. Because Unit 1, Cycle 24 operation will span portions of the fourth and fifth 10-year ISI intervals, the applicable codes are provided for both intervals.
Interval Section XI Interval Start Date Interval End Date Edition/Addenda Fourth 2007 Edition, through June 01, 2014 May 31, 2024 2008 addenda Fifth 2019 Edition June 01, 2024 May 31, 2034
For the purpose of this document, all references will be to the current fourth 10-year ISI interval ASME Code,Section XI edition and addenda of record.
- 3. Applicable Code Requirement
The ASME Code,Section XI, IWB-5222(b) requires the system leakage test pressure retaining boundary to extend to all Class 1 components within the system boundary.
Specifically, IWB-5222(b) states,
The Class 1 pressure retaining boundary which is not pressurized when the system valves are in the position required for normal reactor startup shall be pressurized and examined at or near the end of the inspection interval. This boundary may be
Enclosure 1 to PLA-8112 Page 2 of 7
tested in its entirety or in portions and testing may be performed during the testing of the boundary of IWB-5222(a).
- 4. Reason for Request
In accordance with 10 CFR 50.55a(z)(2), relief is requested on the basis that compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
4.1 System Description
The Main Steam system is primarily a power generation system. The Main Steam system transports steam generated in the reactor pressure vessel (RPV) through primary containment to the main steam turbine by means of the four 24-inch main steam lines (26-inch from the RPV to the outboard main steam isolation valves (MSIVs)); these lines are referred to as main steam lines (MSLs) A, B, C, and D. Each MSL contains two MSIVs, one inside and one outside the primary containment; these MSIVs are referred to as inboard (IB) and outboard (OB),
respectively. The MSIVs are designed to close on appropriate signals to prevent uncontrolled primary coolant release to the environment in the event of a steam line break downstream of the MSIVs. This action limits the loss of coolant and the release of radioactive materials from the nuclear system.
4.2 Physical Hardship
SSES Unit 1 entered Mode 5 on March 26, 2024, for the scheduled refueling and inspection outage (RIO). In accordance with Susquehannas 10 CFR 50, Appendix J (hereafter, Appendix J) program, all MSL penetrations were leakage tested by pressurizing between the IB and OB MSIVs to containment peak pressure. Combined as-found leakage through the MSLs was less than the 300 standard cubic feet per hour limit specified in Technical Specification (TS)
Surveillance Requirement (SR) 3.6.1.3.12. While leakage through D OB MSIV (HV141F028D) was less than the limit specified in TS SR 3.6.1.3.12, Susquehanna elected to emergently work the valve. However, due to the scope of work being performed on HV141F028D and its potential scheduling and resource impacts on the performance of the IWB-5222(b) pressure boundary test, Susquehanna concludes that performing the entirety of the IWB-5222(b) pressure boundary test during the ongoing 2024 RIO would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
The ASME Code,Section XI, IWB-5222(b) permits the Class 1 pressure retaining boundary to be tested in its entirety or in portions concurrent with the boundary testing required by IWB-5222(a). This allowance permits Susquehanna to perform the IWB-5222(b) pressure boundary test to the IB D MSIV (and the remainder of all piping applicable to the IWB-5222(b) boundary), then perform pressure boundary test between the IB and OB D MSIVs
Enclosure 1 to PLA-8112 Page 3 of 7
such that the full intent of IWB-5222(b) is met. This, however, presents hardship or unusual difficulty without a compensating increase in the level of quality and safety.
Susquehanna has not adequately prepared to execute pressure boundary testing between the IB and OB D MSIVs. Since the HV141F028D work and, by extension, the impact to the IWB-5222(b) pressure boundary test was not anticipated, Susquehanna has not planned the test evolution in this configuration. Consideration must be given to the potential risks associated with performing a non-routine test, including but not limited to,
- No procedure has been developed,
- First time evolution for Susquehanna (i.e., no internal operating experience), and
- Potential for damage to the IB MSIV as pressure will be in the opposite direction of accident conditions.
Additionally, performance of a partial IWB-5222(b) pressure boundary test (between the IB and the OB D MSIVs) would require the station to complete the Class 1 pressure boundary testing multiple times and, by extension, suspend shutdown cooling operation during each IWB-5222(b) evolution. The IWB-5222(b) pressure boundary test is classified as an infrequently performed test or evolution due to the infrequent occurrence and potential consequence of error. This scenario also introduces further risk due to the coordinated vessel level manipulations involved, the sequence of which is not currently captured within the scope of Susquehannas vessel letdown and reassembly procedure.
The potential risks associated with testing between the IB and OB D MSIVs are unnecessary given the testing performed over the interval; refer to Tables 5.1 and 5.2 in Section 5.
Specifically, from the beginning of the interval (i.e., June 01, 2014) through the 2020 RIO, Susueqhanna performed the IWB-5222(a) pressure boundary testing to the OB MSIVs. No adverse conditions were noted in these tests. These previously performed tests and the partial IWB-5222(b) pressure boundary test (including all piping applicable to the IWB-5222(b) pressure boundary and the Main Steam system MSL D to the IB MSIV) to be performed in the 2024 RIO, provide reasonable assurance that the Class 1 pressure boundary is adequately leak tight. Specifically, when these tests are considered in aggregate, the entire Class 1 pressure boundary is shown to be pressure tested to requirements of IWB-5222(b) within the fourth 10-year ISI interval.
Additionally, if Susquehanna were to postpone performance of the IWB-5222(b) pressure boundary testing until the HV141F028D work is complete such that the IWB-5222(b) can be performed one time and in its entirety during the current RIO, the RIO would be significantly extended. Delay in performing the IWB-5222(b) pressure boundary test will delay continued progress through the RIO activities, potentially delaying any further discovery items which may require specialty contract staff to support repairs. This delay would also likely impact specialty contract staff supporting vessel/drywell reassembly activities. Susquehanna plans months to years in advance to acquire specialty contract staff to support these activities. The population of
Enclosure 1 to PLA-8112 Page 4 of 7
contract staff to support nuclear RIOs is limited and is shared with the entire nuclear community. Significant delays in schedule will likely result in the loss of contract staff to other utilities such that Susquehannas ability to exit the RIO would be adversely impacted, delaying restoration of clean energy to the grid.
Due to the hardships described above, relief is needed to reduce the risk of human performance errors during shutdown cooling suspension, vessel level manipulations, and vessel/drywell reassembly.
- 5. Proposed Alternative and Basis for Use
In accordance with 10 CFR 50.55a(z)(2), the proposed alternative is to perform a partial IWB-5222(b) pressure boundary test during the 2024 RIO, including all piping applicable to the IWB-5222(b) pressure boundary and the Main Steam system MSL D to the IB MSIV, and subsequently test the remainder of the boundary (all piping applicable to the IWB-5222(a) pressure boundary and the Main Steam system MSL D to the OB MSIV) during the next Unit 1 RIO (projected for spring 2026). When these tests are considered in aggregate, the requirements to test the IWB-5222(b) boundary have been met. This option would not alter or negate the need to perform the fifth 10-year ISI IWB-5222(b) pressure boundary test at or near the end of the fifth interval (i.e., 2034).
A boundary sketch is provided in Enclosure 2. The highlighted piping between HV141F022D and HV141F028D represents the volume proposed to be omitted in 2024 and to be tested in the next Unit 1 RIO (projected for spring 2026).
The 2024 partial IWB-5222(b) pressure boundary test to the IB D MSIV and the next Unit 1 RIO IWB-5222(a) pressure boundary test to the OB D MSIV, will be performed in accordance with approved ASME Class 1 Boundary System Leakage Test procedures. The ASME Class 1 test boundary will be pressurized to the RPV test pressure range of 1035 to 1045 pounds per square inch gauge (psig). The pressure tests will be evaluated by qualified VT-2 examiners completing visual examinations of the test boundaries in accordance with the approved RPV pressure test procedure.
Susquehanna will utilize the intervening cycle to develop adequate test procedures to perform the IWB-5222(a) pressure boundary test with the Main Steam system MSL D to the OB MSIV during the next Unit 1 RIO (projected for spring 2026).
Approval of the proposed alternative is requested by April 12, 2024.
Enclosure 1 to PLA-8112 Page 5 of 7
Basis for Use Susquehanna is requesting deferral of the pressure boundary testing between the IB and OB D MSIVs until the next Unit 1 RIO (projected for spring 2026). The request would not alter the June 01, 2024, start date for the fifth 10-year ISI Interval and subsequent ISI intervals. With the approval of this request, pressure testing of the volume between the IB and OB D MSIVs would be deferred until the next Unit 1 RIO (projected for spring 2026). All other applicable piping would be tested to the IWB-5222(b) requirements during the ongoing 2024 RIO. This option would not affect the requirement to perform the fifth 10-year ISI IWB-5222(b) pressure boundary test at or near the end of the fifth interval (i.e., 2034).
The April 2020 Unit 1 IWB-5222(a) pressure boundary test to the OB MSIVs provides reasonable assurance of leak tightness of the volume subject to the deferred testing. There are no known degradation mechanisms in the MSLs which would impact the structural integrity of the piping or piping welds. Additional testing has been performed on the applicable piping during each of the Unit 1 RIOs since 2014 as noted in Tables 5.1 and 5.2 below. Previous testing of the applicable piping provides a reasonable level of assurance that the integrity of the piping is adequate to support deferment of testing of the subject volume until the next Unit 1 RIO (projected for spring 2026).
Leakage and Pressure Testing The following table provides a summary of ASME Code Section XI and Appendix J Local Leak Rate Testing that has been completed on the subject piping from the end of the third 10-year ISI interval (i.e., the last performance of the IWB-5222(b), Class 1 Boundary System Leakage Test) to the current RIO.
Table 5.1: Leakage and Pressure Testing History Line Function Test Boundary Test Pressure Year
/ Result Reactor Pressure IWB-5222(b), Class 1 RPV and Class 1 piping 1035.9 psig 2014 Vessel and Boundary System per IWB-5222(b) SAT Class 1 Piping Leakage Test Main Steam Appendix J Local HV141F022D to 26.3 psig 2016 Leak Rate Test HV141F028D SAT Main Steam IWB-5222(a), Class1 Includes up to 1039.9 psig 2016 Boundary System HV141F028D SAT Leakage Test Main Steam Appendix J Local HV141F022D to 25.5 psig 2018 Leak Rate Test HV141F028D SAT Main Steam IWB-5222(a), Class1 Includes up to 1038 psig 2018 Boundary System HV141F028D SAT Leakage Test
Enclosure 1 to PLA-8112 Page 6 of 7
Table 5.1: Leakage and Pressure Testing History Line Function Test Boundary Test Pressure Year
/ Result Main Steam Appendix J Local HV141F022D to 25.2 psig 2020 Leak Rate Test HV141F028D SAT Main Steam IWB-5222(a), Class1 Includes up to 1036 psig 2020 Boundary System HV141F028D SAT Leakage Test Main Steam Appendix J Local HV141F022D to 25.1 psig 2022 Leak Rate Test HV141F028D SAT Main Steam IWB-5222(a), Class1 Includes up to 1036.7 psig 2022 Boundary System HV141F022D SAT Leakage Test Main Steam Appendix J Local HV141F022D to 25.1 psig 2024 Leak Rate Test HV141F028D SAT
Additionally, during normal plant operation this section of piping is pressurized to approximately reactor conditions. No evidence of through wall leakage has been noted (e.g.,
staining/rust at the penetration, no insulation debris). Although this is not a substitute for the IWB-5222(b) test it does provide additional assurance that the piping integrity is maintained.
Non-Destructive Examinations As shown in the table below, between 2020 and 2024, one non-destructive exam was completed on the piping subject to this relief request.
Table 5.2: Non-Destructive Examination History Line Function Test Boundary Test Pressure Year
/ Result Main Steam Volumetric Weld upstream of N/A 2020 (Ultrasonic Test) HV141F028D SAT Weld Exam
Note, this request does not impact or alter the requirements of Appendix J. HV141F028D will be leak rate tested in accordance with Appendix J and SSES Unit 1 TS 3.6.1.3 during the 2024 RIO.
- 6. Duration of Proposed Alternative
Use of this proposed alternative is applicable to Unit 1, Cycle 24 operation through the end of the Unit 1 RIO which is projected to occur in spring 2026.
Enclosure 1 to PLA-8112 Page 7 of 7
The fourth 10-year ISI interval for Unit 1 ends on May 31, 2024. The fifth 10-year ISI interval for Unit 1 will begin on June 01, 2024, and is currently scheduled to end on May 31, 2034.
Because Unit 1, Cycle 24 operation (and by extension, the proposed alternative) will span portions of the fourth and fifth 10-year ISI intervals, Susquehanna requests that the proposed alternative cover the remainder of the current fourth 10-year ISI interval and the portion of the fifth 10-year ISI interval commencing at the start of the interval (i.e., June 01, 2024) and concluding with the end of Unit 1, Cycle 24 (projected for spring 2026).
- 7. Precedent
7.1 Letter from NRC to Brunswick Steam Electric Plant, Brunswick Steam Electric Plant, Unit 2 - Relief from the Requirements of the ASME Code,Section XI, ISI-11 Regarding System Leakage Test of Class 1 Piping (EPID L-2018-LLR-0038), dated May 07, 2018 (ADAMS Accession No. ML18122A203).
Security-Related Information - Withhold in Accordance with 10 CFR 2.390
Enclosure 2 to PLA-8112
Boundary Drawing
Drawing SE-100-002, Sheet 1, Revision 10