ML19099A263

Issuance of Relief Request 14R-08, Revision 1, Regarding Pressure Testing of Containment Atmospheric Control Penetration Piping

ML19099A263
Person / Time
Site:	Limerick
Issue date:	04/22/2019
From:	James Danna Plant Licensing Branch 1
To:	Bryan Hanson Exelon Generation Co, Exelon Nuclear
Sreenivas V, NRR/DORL/LPLI, 415-2597
References
EPID L-2018-LLR-0127
Download: ML19099A263 (8)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, O.C. 20555.0001 April 22, 2019 Mr. Bryan C. Hanson Senior Vice President Exelon Generation Company, LLC President and Chief Nuclear Officer Exelon Nuclear 4300 Winfield Road Warrenville, IL 60555

SUBJECT:

LIMERICK GENERATING STATION, UNITS 1 AND 2- ISSUANCE OF RELIEF REQUEST 14R-08, REVISION 1, REGARDING PRESSURE TESTING OF CONTAINMENT ATMOSPHERIC CONTROL PENETRATION PIPING (EPID L-2018-LLR-0127)

Dear Mr. Hanson:

By letter dated October 1, 2018 (Agencywide Documents Access and Management System Accession No. ML18274A015), Exelon Generation Company, LLC (Exelon, the licensee) submitted Relief Request 14R-08, Revision 1, proposing an alternative to the system leakage test requirements of American Society of Mechanical Engineers Boiler & Pressure Vessel Code (ASME Code), Section XI, "Rules for lnservice Inspection of Nuclear Power Plant Components,"

Table IWC-2500-1, Examination Category C-H, at the Limerick Generating Station, Units 1 and 2.

Specifically, pursuant to Title 10 of the Code of Federal Regulations ( 10 CFR) 50.55a(z)( 1), the licensee proposed to use the local leak rate tests (LLRTs) in accordance with 10 CFR Part 50, Appendix J, Option B. The licensee stated that the proposed alternative to the ASME Code provides an acceptable level of quality and safety.

The U.S. Nuclear Regulatory Commission (NRC) staff has determined that the proposed alternative in Revision 1 to Relief Request 14R-08 provides an acceptable level of quality and safety. Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(z)( 1). Therefore, the NRC staff authorizes the use of the proposed alternative for the fourth inservice inspection interval of Limerick Generating Station, Units 1 and 2, which is scheduled to end on January 31, 2027.

All other ASME Code, Section XI requirements for which relief was not specifically requested and approved in the subject request for relief remain applicable, including third-party review by the Authorized Nuclear lnservice Inspector.

B. Hanson If you have any questions, please contact the Limerick Generating Station Project Manager, V. Sreenivas, at 301-415-2597 or V.Sreenivas@nrc.gov.

Sincerely, c=-~-~

1 James G. Danna, Chief Plant Licensing Branch I

~

Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-352 and 50-353

Enclosure:

Safety Evaluation cc: Listserv

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELIEF REQUEST 14R-08, REVISON 1. REGARDING PRESSURE TESTING OF CONTAINMENT ATMOSPHERIC CONTROL PENETRATION PIPING EXELON GENERATION COMPANY. LLC LIMERICK GENERATING STATION, UNITS 1 AND 2 DOCKET NOS. 50-352 AND 50-353

1.0 INTRODUCTION

By letter dated October 1, 2018 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML18274A015), Exelon Generation Company, LCC (Exelon or the licensee) submitted Relief Request 14R-08, Revision 1, for the Limerick Generating Station (Limerick), Units 1 and 2. In the relief request, the licensee proposed an alternative to the system leakage test requirements of American Society of Mechanical Engineers Boiler &

Pressure Vessel Code (ASME Code), Section XI, "Rules for lnservice Inspection of Nuclear Power Plant Components," Table IWC-2500-1, Examination Category C-H.

Specifically, pursuant to Title 10 of the Code of Federal Regulations ( 10 CFR) 50.55a(z)(1 ), the licensee proposed to use the local leak rate tests (LLRTs) in accordance with 10 CFR Part 50, Appendix J, Option B. The licensee stated that the proposed alternative to the ASME Code provides an acceptable level of quality and safety.

2.0 REGULATORY EVALUATION

Components (including supports) that are classified as ASME Code Class 1, Class 2, and Class 3 must meet the requirements in 10 CFR 50.55a(g)(4) throughout the service life of a boiling or pressurized water reactor to the extent practical within the limitations of design, geometry, and materials of construction of the components. The exception is the design and access provisions and preservice examination requirements set forth in Section XI of editions and addenda of the ASME Code that become effective subsequent to editions specified in paragraphs (g)(2) and (3) of 10 CFR 50.55a and that are incorporated by reference in paragraph (a)(1 )(ii) or (iv) for snubber examination and testing of 10 CFR 50.55a.

The provision in 10 CFR 50.55a(z)(1) allows that alternatives to the requirements of paragraph (g) of 10 CFR 50.55a may be used, when authorized by the NRC, if the licensee demonstrates that the proposed alternative provides an acceptable level of quality and safety.

Enclosure

Based on the foregoing discussion and subject to the following technical evaluation, the NRC staff finds that regulatory authority exists for the licensee to request the use of an alternative and the NRC to authorize the proposed alternative.

3.0 TECHNICAL EVALUATION

3.1 ASME Code Component(s) Affected The proposed alternative applies to ASME Code Class 2 primary containment atmospheric control piping components. For Limerick, Unit 1, the relief request pertains to the following piping:

• Hydrogen/oxygen sample lines HCB-116, between and including containment penetrations X-28A and X-288 and valves SV-57-142, SV-57-143, SV-57-144, and SV-57-195

• Drywall low flow nitrogen makeup line HCB-116, between and including containment penetration X-62 and valves HV-57-116 and SV-57-159

• Hydrogen/oxygen sample lines HCB-116, between and including containment penetration X-221A and valves SV-57-141 and SV-57-184

• Nitrogen purge line HBB-125, between and including valves HV-57-109, HV-57-121, and HV-57-131

• Drywall air purge line HBB-124, between and including valves HV-57-123 and HV-57-135.

• Suppression pool air purge line HBB-126, between and including valves HV-57-124 and HV-57-147.

• Drywall purge to standby gas treatment line HBB-127, between and including valves HV-57-114 and HV-57-115, and line HCB-117, between and including connection to line HBB-127 and valve SV-57-145.

• Suppression pool low flow nitrogen makeup line HCB-116, between and including containment penetration X-220A, valve SV-57-190, and connection to drywall low flow nitrogen makeup line HCB-116.

• Hydrogen/oxygen sample line HCB-116, between and including containment penetration X-2218 and valves SV-57-186 and HV-55-126.

• Drywall purge exhaust bypass line HBB-127, between and including valves 57-1807 and HV-57-117.

• Suppression pool purge exhaust bypass line HBB-128, between and including valves 57-1810 and HV-57-118.

• Suppression pool purge air exhaust lines HBB-128 and HCB-117, between and including valves HV-57-104, HV-57-112, and SV-57-185.

For Limerick, Unit 2, the relief request pertains to the following piping:

• Hydrogen/oxygen sample lines HCB-216, between and including containment penetrations X-28A and X-288 and valves SV-57-242, SV-57-243, SV-57-244 and SV-57-295.

• Drywell low flow nitrogen makeup line HCB-216, between and including containment penetration X-62 and valves HV-57-216 and SV-57-259.

• Hydrogen/oxygen sample lines HCB-216, between and including containment penetration X-221A and valves SV-57-141 and SV-57-284.

• Nitrogen purge line HBB-225, between and including valves HV-57-209, HV-57-221, and HV-57-231.

• Drywell air purge line HBB-224, between and including valves HV-57-223 and HV-57-235.

• Suppression pool air purge line HBB-226, between and including valves HV-57-224 and HV-57-247.

• Drywell purge to standby gas treatment line HBB-227, between and including valves HV-57-214 and HV-57-215, and line HCB-217, between and including connection to line HBB*:-227 and valve SV-57-245.

• Suppression pool low flow nitrogen makeup line HCB-216, between and including containment penetration X-220A, valve SV-57-290, and connection to drywell low flow nitrogen makeup line HCB-216.

• Hydrogen/oxygen sample line HCB-216, between and including containment penetration X-221 Band valve SV-57-286.

• Drywell purge exhaust bypass line HBB-227, between and including valves 57-2815 and HV-57-217.

• Suppression pool purge exhaust bypass line HBB-228, between and including valves 57-2818 and HV-57-218.

• Suppression pool purge air exhaust lines HBB-228 and HCB-217, between and including valves HV-57-204, HV-57-212, and SV-57-285.

• Hardened containment vent line HBB-272, between and including valves HV-57V-280 and HV-57V-281.

These components are subject to Examination Category C-H, Item Number C7.10 of ASME Code, Section XI, Table IWC-2500-1.

3.2 Applicable ASME Code Edition and Addenda The current code of record for Limerick, Units 1 and 2, is the 2007 Edition through the 2008 Addenda of the ASME Code, Section XI.

3.3 Applicable ASME Code Requirements IWC-2500(a) of the ASME Code, Section XI, states that components shall be examined and pressure tested as specified in Table IWC-2500-1. Specifically, Examination Category C-H, Item No. C7.10 of Table IWC-2500-1, requires the performance of VT-2 visual examination on the subject components during the system leakage test for each inspection period.

3.4 Licensee's Proposed Alternative In accordance with 10 CFR Part 50, Appendix J, Option B, the licensee currently performs LLRTs each refueling outage. The licensee proposed to use the LLRTs as an alternative to the system leakage test specified in ASME Code, Section XI, Table IWC-2500-1.

3.5 Licensee's Basis of the Proposed Alternative Pursuant to 10 CFR 50.55a(z)( 1), the licensee requested the relief on the basis that the proposed alternative will provide an acceptable level of quality and safety. The licensee's basis of the proposed alternative is summarized below.

During the normal plant operation, the subject piping is either isolated or less than 1 pounds per square inch (psig) (normal containment pressure), and the pressurizing fluid is essentially nitrogen gas. A VT-2 visual examination looking for nitrogen gas leakage with less than 1 psig pressure would be inconclusive. During the LLRTs, the subject piping is pressurized to 44 psig, a substantially higher pressure than that developed during a periodic system functional test.

Therefore, the LLRTs offer the following advantages over system leakage tests of the subject piping: LLRTs have the ability to quantify leakage that is not feasible with a VT-2 visual examination on this essentially gas-filled piping, conservatively including through-valve leakage that would not be identified in a VT-2 visual examination.

In addition, IWC-521 O(b )(2) allows for gas tests, which locate and detect through-wall leakage.

In the event the LLRT fails to meet its acceptance criteria, further testing would be performed to determine the location of the leaks, appropriate corrective maintenance, and an appropriate retest would be performed.

3.6 Duration of the Proposed Alternative The duration of the relief request is the fourth 10-year inservice inspection interval of Limerick, Units 1 and 2, which is scheduled to end on January 31, 2027.

3. 7 NRC Staff Evaluation The licensee previously submitted Relief Request 14R-08 by letter dated April 13, 2016 (ADAMS Accession No. ML16104A122). The previous request was approved in the NRC staff's safety evaluation dated February 6, 2017 (ADAMS Accession No. ML17006A268). In this revision (Revision 1) to Relief Request 14R-08, the licensee added the Limerick, Unit 2, hardened containment vent line HBB-272 (between and including valves HV-57V-280 and HV-57V-281) in

the scope of the relief request. The licensee stated that this revision resulted from the installation of the hardened vent modification in Limerick, Unit 2.

As discussed in the NRC's safety evaluation dated February 6, 2017, Examination Category C-H requires a vr-2 visual examination of the pressure retaining boundary during a system leakage test in accordance with paragraph IWC-5221 of the ASME Code, Section XI.

Specifically, paragraph IWC-5221 requires that the system leakage test shall be conducted at the system pressure obtained while the system, or portion of the system, is in service performing its normal operating function, or at the system pressure developed during a test conducted to verify system operability.

The licensee's basi~ of the proposed alternative in Relief Request 14R-08, Revision 1, is essentially the same as the basis of the proposed alternative in the previous relief request (Relief Request 14R-08), as follows: (a) a leakage test performed at the normal operating pressure (1 psig) for the subject nitrogen-filled piping would be inconclusive; (b) during the LLRTs, the components are subject to a test pressure of 44 psig, which is a substantially higher pressure than the normal operating pressure; and (c) LLRTs have the ability to quantify leakage that is not feasible with a vr-2 visual examination on this essentially gas-filled piping.

In its review, the NRC staff finds that the LLRTs performed every refueling outage are sufficient to confirm that there is no leakage from the subject piping. In addition, the basis of the proposed alternative is consistently applicable to the piping that is newly added in Revision 1 to Relief Request 14R-08 (i.e., the Unit 2 hardened containment vent line HBB-272).

4.0 CONCLUSION

As set forth above, the NRC staff has determined that the proposed alternative in Revision 1 to Relief Request 14R-08 provides an a9ceptable level of quality and safety. Accordingly, the NRC staff concludes that the licensee has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(z)(1 ). Therefore, the NRC staff authorizes the use of the proposed alternative for the fourth inservice inspection interval of Limerick, Units 1 and 2, which is scheduled to end on January 31, 2027.

All other ASME Code, Section XI requirements for which relief was not specifically requested and approved remain applicable, including third-party review by the Authorized Nuclear lnservice Inspector.

Principal Contributor: S. Min Date:April 22, 2019

8. Hanson

SUBJECT:

LIMERICK GENERATING STATION, UNITS 1 AND 2 - ISSUANCE OF RELIEF REQUEST 14R-08, REVISION 1, REGARDING PRESSURE TESTING OF CONTAINMENT ATMOSPHERIC CONTROL PENETRATION PIPING (EPID L-2018-LLR-0127) DATED APRIL 22, 2019 DISTRIBUTION:

PUBLIC PM File Copy RidsNrrLALRonewicz Resource RidsNrrDorlLpl1 Resource RidsNrrPMLimerick Resource RidsACRS_MailCTR Resource RidsRgn1 MailCenter Resource RidsNrrDmlrMphb Resource SMin, NRR KHoffman, NRR SCumblidge, NRR JQuichocho, OEDO MMcCopppin, OEDO ADAMS Access,on No.: ML19099A263 *b1y memoran d um OFFICE DORL/LPL 1/PM DORL/LPL 1/LA DMLR/MPHB/BC* DORL/LPL 1/BC DORL/LPL 1/PM NAME VSreenivas LRonewicz DAIiey Joanna VSreenivas (SCumblidqe for) (JTobin for)

DATE 04/16/2019 04/12/2019 02/22/2019 04/17/2019 04/22/2019 OFFICIAL RECORD COPY