RS-17-125, Relief Request RV-2 Associated with the Fourth Inservice Testing Interval

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Relief Request RV-2 Associated with the Fourth Inservice Testing Interval
ML17268A365
Person / Time
Site: Byron  Constellation icon.png
Issue date: 09/25/2017
From: Gullott D
Exelon Generation Co
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
RS-17-125
Download: ML17268A365 (8)
v • d • e


Text

~- 4300 Winfield Road Warrenville, IL 60555 ExeLon G 630 657 2000 Office RS-17-125 10 CFR 50.55a(z)

September 25, 2017 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C. 20555-0001 Byron Station, Units 1 and 2 Renewed Facility Operating License Nos. NPF-37 and NPF-66 NRC Docket Nos. STN 50-454 and STN 50-455

Subject:

Relief Request RV-2 Associated with the Fourth Inservice Testing Interval In accordance with 10 CFR 50.55a, "Codes and standards," paragraph (z)(1), Exelon Generation Company, LLC (EGC), is requesting NRC approval of the attached relief request associated with the Fourth Inservice Testing (IST) Interval for Byron Station, Units 1 and 2.

The fourth interval of the Byron Station IST Program is in effect from July 1, 2016 through June 30, 2026. As required by 10 CFR 50.55a(f)(4)(ii), the Byron Station Fourth IST Interval is required to comply with the requirements of the American Society of Mechanical Engineers (ASME) Operation and Maintenance (OM) Code, 2004 Edition through the 2006 Addenda.

The attached relief request proposes an alternative to the requirements of ASME OM Code Mandatory Appendix I, "Inservice Testing of Pressure Relief Devices in Light-Water Reactor Nuclear Power Plants," paragraph 1-1350, "Test Frequency, Classes 2 and 3 Pressure Relief Valves." Specifically, the relief request is proposing to extend the test frequency for a limited number of pressure relief valves (PRVs) (i.e., 10 PRVs) from 48 months to 54 months to allow implementation of a "divisional outage strategy" during refueling outages.

The basis of this request is that the proposed alternative would provide an acceptable level of quality and safety while effectively monitoring the associated components for degradation.

EGC respectfully requests NRC approval of the proposed relief request within one year of submittal; i.e., by September 25, 2018.

There are no regulatory commitments contained within this letter.

September 25, 2017 U. S. Nuclear Regulatory Commission Page 2 Should you have any questions concerning this letter, please contact Joseph A. Bauer at (630) 657-2804.

Respectfully, David M. Gullott Manager Licensing Exeion Generation Company, LLC

Attachment:

10 CFR 50.55a Request Number RV-2 CC' NRC Regional Administrator Region III NRC Senior Resident Inspector Byron Station NRC Project Manager, NRR Byron Station Illinois Emergency Management Agency Division of Nuclear Safety

ATTACHMENT 1 10 CFR 50.55a Request Number RV-2 Test Interval for Classes 2 and 3 Pressure Relief Valves per Mandatory Appendix I, 1-1350 Proposed Alternative Requested in Accordance with 10 CFR 50.55a(z)(1)

Alternative Provides Acceptable Level of Quality and Safety

1. ASME Code Component(s) Affected TABLE 1 Byron Station Pressure Relief Valves, Units 1 and 2 Byron Component Description Class Category IST RV Group

_1S18851 U-1 SI PPS DSCH XT1E TO CL RLF VLV 2 C 1 1 S18853A 1A SI PP TO 1 D LOOP HL RLF VLV 2 C 1 1 S18853B 1 B SI PP TO 1 B/1 C LOOP HL RLF VLV 2 C 1 1 S18856A 1A RH HX TO 1A/1 D LOOP CL RLF VLV 2 C 2 1 S18856B 1 B RH HX TO 1 B/1 C LOOP CL RLF VLV 2 C 2 2S18851 U-2 SI PPS DSCH XTIE TO CL RLF VLV 2 C 3 2SI8853A 2A SI PP TO 2D LOOP HL RLF VLV 2 C 3 2SI8853B 2B SI PP TO 2B/2C LOOP HL RLF VLV 2 C 3 2Si8856A 2A RH HX TO 2A/2D LOOP CL RLF VLV 2 C 4 2SI8856B 2B RH HX TO 2B/2C LOOP CL RLF VLV 2 C 4

2. Applicable Code Edition and Addenda American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code) 2004 Edition through the OMb Code 2006 Addenda
3. Applicable Code Requirement ISTA-3120, Inservice Test Interval, subparagraph (a) states, "The frequency for inservice testing shall be in accordance with the requirements of Section IST."

Mandatory Appendix I, "Inservice Testing of Pressure Relief Devices in Light-Water Reactor Nuclear Power Plants," paragraph 1-1350, "Test Frequency, Classes 2 and 3 Pressure Relief Valves,"

subparagraph (a) 10-year Test Interval, states, in part, that "Classes 2 and 3 pressure relief valves, with the exception of PWR main steam safety valves, shall be tested every 10 years, starting with initial electric power generation. No maximum limit is specified for the number of valves to be tested during any single plant operating cycle; however, a minimum of 20% of the valves from each valve group shall be tested within any 48-month interval. This 20% shall consist of valves that have not been tested during the current 10-year test interval, if they exist...."

Page 1 of 6

ATTACHMENT 1 10 CPR 50.55a Request Number RV-2 Test Interval for Classes 2 and 3 Pressure Relief Valves per Mandatory Appendix 1, 1-1350 Proposed Alternative Requested in Accordance with 10 CFR 50.55a(z)(1)

Alternative Provides Acceptable Level of Quality and Safety

4. Reason for Request In accordance with 10 CFR 50.55a, "Codes and standards," paragraph (z)(1), an alternative is proposed to the Classes 2 and 3 pressure relief valve test frequency requirements of the ASME OM Code. The basis of this request is that the proposed alternative would provide an acceptable level of quality and safety while effectively monitoring the associated components for degradation.

Specifically, this alternative is requested for the associated inservice testing requirements of the Inservice Test (IST) Program pressure relief valves (PRVs) identified in Table 1, "Byron Station Pressure Relief Valves, Units 1 and 2." Note that all the subject valves are Class 2 valves.

Byron Station conducts a refueling outage on each unit once every 18 months. Each unit at Byron Station consists of two redundant safeguard divisions (i.e., Division "A" and Division "B"). Byron Station has implemented a "divisional outage strategy" for equipment maintenance where only either the "A" or "B" division/train equipment/components are taken out-of-service during a given refueling outage. This divisional outage strategy is designed to maintain one division/train of equipment/components fully operational and protected while performing maintenance/testing on the opposite division/train. Based on the 18-month refueling outage frequency, equipment/components of each train will be tested every other outage; i.e., once every 36 months.

There is a total of 65 Class 2 and 3 pressure relief valves in the Byron Station IST program subject to the testing requirements of Mandatory Appendix I, paragraph 1-1350 described above. These valves are divided into 33 different valve "groups" based on manufacturer, type, system application and service media in accordance with the OM Code. The 10 PRVs identified in Table 1 are the valves that comprise valve groups 1 through 4. Group 1 and Group 3 each consist of three valves (i.e., one "A" division valve, one "B" division valve, and a common division valve (i.e., a pump discharge cross-tie valve that is not designated as division specific)). Group 2 and Group 4 each consist of two valves (i.e., one "A" division valve and one B" division valve). Due to the small number of valves in each valve group, some valves in each group must be tested more than once during a 10-year test interval to satisfy the Appendix I, paragraph 1-1350 criteria of testing a minimum of 20% of the valves from each valve group within any 48-month interval.

Due to system availability considerations, valve removal and testing must be performed when the valve's associated unit is in a shutdown mode of operation; therefore, all subject valves are tested during a scheduled refueling outage.

Current PRV Testing Schedule The current Byron Station pressure relief valve testing schedule for the valves listed in Table 1 is presented in Table 3a, "IST Valve Groups 1-4, Current Pressure Relief Valve Test Schedule." As can be seen, it is not possible to align the scheduled PRV testing using the divisional outage strategy and still meet the current Mandatory Appendix I, paragraph 1-1350 requirement of testing 20% of the valves in each group every 48 months without performing a valve test every other outage; i.e., every 36 months. This necessitates performing a test on a "B" division valve during an "A" division outage, or vice versa, contrary to the divisional outage strategy. For example, refer to Table 3a, Group 2 valves (i.e., 2 valves which are both Unit 1 valves). When maintaining a consistent test frequency for each valve in the group, the "B" train valve must be tested during the Unit 1 "A" train outage in Spring 2020; and again, the "B" train valve must be tested during the Unit 1 "A" train outage in Page 2 of 6

ATTACHMENT 1 10 CFR 50.55a Request Number RV-2 Test Interval for Classes 2 and 3 Pressure Relief Valves per Mandatory Appendix 1, 1-1350 Proposed Alternative Requested in Accordance with 10 CFR 50.55a(z)(1)

Alternative Provides Acceptable Level of Quality and Safety Spring 2026. The "cross-division" testing problem could be solved by performing an associated division valve test each refueling outage; however, this approach would result in three additional unnecessary tests for the Group 2 valves. A similar number of additional unnecessary tests would also result for Groups 1, 3 and 4.

5. Proposed Alternative and Basis for Use As an alternative to the ASME OM Code Mandatory Appendix 1, 1-1350(x), Byron Station proposes that the Table 1 Class 2 PRVs shall be tested every 10 years; and a minimum of 20% of the valves from each valve group shall be tested within any 54-month interval (where 20% shall consist of valves that have not been tested during the current 10-year test interval, if they exist).

The proposed change from "20% of relief valves tested within any 48-month interval" to "20% of relief valves tested within any 54-month interval," while maintaining the requirement that every relief valve in each group be tested within a 10-year interval, will allow Byron Station to perform PRV testing on division components during the associated division refueling outage. Specifically, this revised testing frequency (i.e., within any 54-month interval) allows deferring testing of a subject valve group by one outage (i.e., rather that testing a valve every other outage (36 months) to meet the "48-month" testing criteria; the valve may now be tested the following outage (at 54 months).

The 54-month test frequency allows aligning a division valve test with its associated divisional outage consistent with the divisional refueling outage scheduling strategies, with the added benefit of reducing costs and maintaining radiation dose "As Low as Reasonably Achievable." Table 3b, "IST Valve Groups 1-4, Proposed Pressure Relief Valve Test Schedule," shows the details of the proposed alternative. As can be seen, in this hypothetical 10-year test interval, all Group 1 through 4 valves are tested during their associated divisional refueling outage; and each valve is tested effectively the same number of times as in the current schedule (i.e., a total net reduction of only one valve test over the 10-year interval), providing a similar level of quality and safety. Note that no change in test frequency is being proposed for Valve Groups 5 through 33 as these valves are not train-specific.

The small change in service time between tests does not represent a condition adverse to quality nor limit the effective monitoring of the subject valves for evidence of degradation. For each PRV identified in Table 1, for the purpose of determining the need to test additional valves, the as-found set-pressure acceptance criteria is +/-3% of valve nameplate set pressure in accordance with Mandatory Appendix I, subparagraph 1-1350(c), Requirements for Testing Additional Valves, Item (1). Since 1999, 26 as-found set pressure tests have been performed for eight Crosby Model/Part JRAK-BS DS-C-56886 valves installed in six locations (IST RV Groups 1 and 3 from Table 1) and eight Crosby Model/Part JB-35-TD-WR DS-C-56902 valves installed in four locations (IST RV Groups 2 and 4 from Table 1). The tests were performed after the valves were installed for a minimum of two to a maximum of eight operating cycles.

As documented in the Byron Station Corrective Action Program Issue Report 04009661, one PRV in IST RV Group 2 and one in IST RV Group 4 were installed for approximately 12 years (i.e.,

8 operating cycles), exceeded the maximum ASME allowable frequency requirement. As-found test results, as shown in Table 2, "Pressure Relief Valve History," were within +/-3% of the valve set pressure, with the exception of valve 2SI8853B, which lifted low (-8.0%) in 2013. This valve was found with rust in the internals, and the disc insert, nozzle, spindle, guide ring, and disc pin were replaced. The scope was expanded and 2SI8853A and 2S18851 tested satisfactorily the next Page 3 of 6

ATTACHMENT 1 10 CFR 50.55a Request Number RV-2 Test Interval for Classes 2 and 3 Pressure Relief Valves per Mandatory Appendix 1, 1-1350 Proposed Alternative Requested in Accordance with 10 CFR 50.55a(z)(1)

Alternative Provides Acceptable Level of Quality and Safety outage. The as-found seat leakage test results were within the Byron Station established seat leakage criteria with the exception of valve 1 S18856A, which exhibited a continuous drip in 2005.

This valve was disassembled, cleaned, lapped, reassembled; and subsequently met the test acceptance criteria. There have been no other occurrences of seat leakage.

These test results show limited time-related degradation or setpoint drift and provide evidence of acceptable previous component performance. This data supports the acceptability of the requested test interval extension from the current 48 months to 54 months (i.e., three fuel cycles). As noted, the small change in service time between tests does not represent a condition adverse to quality nor limit the effective monitoring of the subject valves for evidence of degradation.

The Emergency Core Cooling System (ECCS) PRVs listed in Table 1 are located in water-filled piping outside the Primary Containment Building. The valves are installed downstream of their respective Safety Injection (SI) or Residual Heat Removal (RHR) pumps, which take a suction from the Refueling Water Storage Tank (RWST). The RWST fluid media is purified borated water. The subject valves have been operated in a controlled, mild environment with small swings in temperature and humidity. Test history has shown that the fluid media and environment have not accelerated degradation of the PRVs. Therefore, future accelerated degradation is not expected.

The ability to detect degradation and ensure the operational readiness of the Class 2, SI system PRVs to perform their intended function is assured based on the relief valve test history and by performing the required inspection and testing at the proposed alternative frequency.

Accordingly, the proposed alternative of increasing the interval from 48 months to 54 months (i.e.,

three fuel cycles) for testing 20% of PRVs in a group will continue to provide assurance of the pressure relief valves' operational readiness and provides an acceptable level of quality and safety in accordance with 10 CFR 50.55a(z)(1).

6. Duration of Proposed Alternative This request, upon approval, will be applied to the Byron Station Fourth 10-Year IST Interval, which started on July 1, 2016, and ends June 30, 2026.
7. Precedence IIC*=

Page 4 of 6

ATTACHMENT 1 10 CFR 50.55a Request Number RV-2 Test Interval for Classes 2 and 3 Pressure Relief Valves per Mandatory Appendix I, 1-1350 Proposed Alternative Requested in Accordance with 10 CFR 50.55a(z)(1)

Alternative Provides Acceptable Level of Quality and Safety TABLE 2 Pressure Relief Valve History As-Found As-Found Valve Unit / Set As-Found Removal Set Deviation Leakage Number Division Pressure Requirement Test Date Pressure 2SI8853A 2/A 9/22/2002 1750 1770 1697-1803 1.1% 0 5/1/2010 1750 1750 1697-1803 0.0% 0 10/10/2014 1750 1720 1697-1803 -1.7% 0 2SI8853B 2/B 9/29/2005 1750 1775 1697-1803 1.4% 0 4/23/2013 1750 1610 1697-1803 -8.0% 0 2S18851 2/Common 11/3/1999 1750 1765 1697-1803 0.9% 0 4/22/2007 1750 1755 1697-1803 0.3% 0 10/7/2014 1750 1725 1697-1803 -1.6% 0 1SI8853A 1 /A 10/212000 1750 1750 1697-1803 0.0% 0 9/29/2009 1750 -1800 1697-1803 2.9% 0 1SI8853B 1/B 9/28/2003 1750 1755 1697-1803 0.3% 0 9/20/2012 1750 1760 1697-1803 0.6% 0

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1S18851 1 / Common 9/22"5/+2006 1750 1705 1697-1803 -2.6% 0 9/28/2015 1750 1770 1697-1803 1.1% 0 1 S18856A 1/A 3/11/2005 600 612 582-618 2.0% cont. drip 3/29/2011 600 595 582-618 -0.8% 0 3/11/2017 600 608 582-618 1.3% 0 1 S18856B 1/B 3/19/2002 600 610 582-618 1.7% 0 4/6/2008 600 612 582-618 2.0% 0 3/19/2014 600 600 582-618 0.0% 0 2SI8856A 2/A 3/31/2004 600 610 582-618 1.7% 0 5/1/2010 600 610 582-618 1.7% 0 4/26/2016 600 592 582-618 -1.3% 0 2SI8856B 2/B 4/15/2001 600 594 582-618 -1.0% 0 4/17/2007 600 600 582-618 0.0% 0 4/18/2013 600 610 582-618 1.7% 0 Page 5 of 6

ATTACHMENT 1 10 CFR 50.55a Request Number RV-2 Test Interval for Classes 2 and 3 Pressure Relief Valves per Mandatory Appendix I, 1-1350 Proposed Alternative Requested in Accordance with 10 CFR 50.55a(z)(1)

Alternative Provides Acceptable Level of Quality and Safety TABLE 3a IST Valve Groups 1 4 Current Pressure Relief Valve Test Schedule 2017 2018 2015 2020 2021 2022 2023 2024 2025 2026 spring fall spring fall spring fall spring fall spring fall spring fall spring fall spring fall spring fall spring fall Unit 1 Unit 2 Unit 1 Unit 2 Unit 1 Unit 2 Unit 1 Unit 2 l nit 1 Unit 2 Unit 1 Unit 2 Unit 1 Unit 2 IST RV A-train B-train B-train A-train A-train B-train B-train A-train A-train B-train B-train A-train A-train B-train Group outage outage outage outage outage outage outage outage outage I outage outage I outage outage outage 1 A valve

  • B valve coin valve 2 A valve B valve
  • A valve B valve "

3 B valve coin valve A valve ' B valve 4 B valve " A valve B valve "

Note: (*) indicates incorrect divisional outage alignment TABLE 3b IST Valve Groups 1 4 Proposed Pressure Relief Valve Test Schedule 2017 2018 2019 2020 2021 2022 2023 2024 2025 2026 spring fall spring fall spring fall spring fall spring fall spring fall spring fall spring fall spring fall spring fall Unit 1 Unit 2 Unit 1 Unit 2 Unit 1 Unit 2 Unit 1 Unit 2 Unit 1 Unit 2 Unit 1 Unit 2 Unit 1 Unit 2 IST RV A-train B-train B-train A-train A-train B-train B-train A-train A-train B-train B-train A-train A-train B-train Group I outage outage outage outage outage outage outage outage outage outage outage outage outage outage 1 A valve B valve corn valve A valve 2 A valve B valve A valve 3 B valve coin valve A valve B valve 4 B valve I I I I A valve Note: Correct train alignment is achieved using proposed 54-month interval Page 6 of 6

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