ML19205A353
| ML19205A353 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 08/05/2019 |
| From: | James Danna Plant Licensing Branch 1 |
| To: | Bryan Hanson Exelon Generation Co |
| Sreenivas V, NRR/DORL/LPL1, 415-2596 | |
| References | |
| EPID L-2018-LLR-0382, EPID L-2018-LLR-0383 | |
| Download: ML19205A353 (12) | |
Text
August 5, 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:
R. E. GINNA NUCLEAR POWER PLANT- ISSUANCE OF RELIEF REQUEST ASSOCIATED WITH ALTERNATIVES GR-01, VR-01, AND VR-02 FOR THE SIXTH 10-YEAR INSERVICE TESTING PROGRAM (EPID L-2018-LLR-0382; EPID L-2018-LLR-0383)
Dear Mr. Hanson:
By letter dated December 13, 2018 (Agencywide Documents Access and Management System Accession No. ML18347B036), Exelon Generation Company, LLC (the licensee) requested relief from the requirements of the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code), associated with valve inservice testing for the R. E. Ginna Nuclear Power Plant (Ginna).
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(2), the licensee requested to use the proposed alternatives in requests GR-01, VR-01, and VR-02 on the basis that the ASME OM Code requirements present an undue hardship, without a compensating increase in the level of quality or safety.
The U.S. Nuclear Regulatory Commission (NRC) staff has determined that compliance with the specified requirements would result in hardship or unusual difficulty, without a compensating increase in the level of quality and safety. Accordingly, the NRC staff concludes that the licensee has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(z)(2).
Therefore, the NRC staff authorizes the use of these alternative requests for the sixth 10-year IST program interval, which begins on January 1, 2020, and is scheduled to end on December 31, 2029.
All other ASME OM Code requirements for which relief was not specifically requested and approved in the subject request for relief remain applicable.
B. Hanson If you have any questions, please contact the Ginna Project Manager, V. Sreenivas, at 301-415-2597 or V.Sreenivas@nrc.gov.
Sincerely,
/RA/
James G. Danna, Chief Plant Licensing Branch I Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket No. 50-244
Enclosure:
Safety Evaluation cc: Listserv
ML19205A353 *by memorandum OFFICE DORL/LPL1/PM DORL/LPL1/LA DE/EMIB/BC* DORL/LPL1/BC DORL/LPL1/PM NAME VSreenivas KEntz; SBailey JDanna VSreenivas LRonewicz DATE 07/29/2019 07/29/2019 07/18/2019 08/02/2019 08/05/2019 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION ALTERNATIVE REQUESTS GR-01, VR-01 AND VR-02 FOR SIXTH 10-YEAR INTERVAL INSERVICE TESTING PROGRAM EXELON GENERATION COMPANY, LLC R. E. GINNA NUCLEAR POWER PLANT DOCKET NO. 50-244
1.0 INTRODUCTION
By letter dated December 13, 2018 (Agencywide Documents and Access Management System (ADAMS) Accession No. ML18347B036), Exelon Generation Company, LLC (the licensee) submitted alternatives to the requirements of the American Society of Mechanical Engineers (ASME) Code for Operation and Maintenance of Nuclear Power Plants (OM Code) associated with valve inservice testing (IST) at R. E. Ginna Nuclear Power Plant (Ginna).
Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) 50.55a(z)(2), the licensee requested to use the proposed alternatives in requests GR-01, VR-01, and VR-02 on the basis that the ASME OM Code requirements present an undue hardship, without a compensating increase in the level of quality or safety.
2.0 REGULATORY EVALUATION
The regulation in 10 CFR 50.55a(f), states, in part, that IST of certain ASME Code Class 1, 2, and 3 pumps and valves be performed in accordance with the specified ASME OM Code and applicable addenda incorporated by reference in the regulations.
The regulation in 10 CFR 50.55a(z) states that alternatives to the requirements of paragraph (f) of 10 CFR 50.55a may be used, when authorized by the U.S. Nuclear Regulatory Commission (NRC), if the licensee demonstrates (1) the proposed alternatives would provide an acceptable level of quality and safety or (2) compliance with the specified requirements would result in hardship or unusual difficulty, without a compensating increase in the level of quality and safety.
3.0 TECHNICAL EVALUATION
3.1 Licensees Alternative Request GR-01 The request is proposed in accordance with 10 CFR 50.55a(z)(2) for the duration of the sixth 10-year IST program interval at Ginna.
Enclosure
Applicable Code Requirements ASME OM Code 2012 Edition ISTC-3630, Leakage Rate for Other Than Containment Isolation Valves, states, in part:
Category A valves with a leakage requirement not based on an Owners 10 CFR 50, Appendix J program, shall be tested to verify their seat leakages
[are] within acceptable limits. Valve closure before seat leakage testing shall be by using the valve operator with no additional closing force applied.
ISTC-3630(a), Frequency, states, Tests shall be conducted at least once every 2 yr [years].
Affected Components The request applies to the safety injection motor-operated valves (MOV) and check valves (CV) listed in the following table. The licensee stated, These Reactor Coolant System (RCS)
Pressure Isolation Valves (PIVs) function to provide reactor coolant system pressure boundary isolation.
Valve System Code Class Category Configuration/Type 878A SI 2 A MOV 878C SI 2 A MOV 877A SI 1 A/C Event V CV 877B SI 1 A/C Event V CV 878F SI 1 A/C Event V CV 878H SI 1 A/C Event V CV
Reason for Request
The licensee stated:
Pursuant to 10 CFR 50.55a, Codes and Standards, paragraph (z)(2), an alternative to the requirement of ASME OM-2012 Code, paragraph ISTC-3630(a) is proposed. The basis of the request is that compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
Safety injection (SI) hot leg check valves 877A, 877B, 878F, and 878H and motor operated valves (MOVs) 878A and 878C are considered to be passive. During operation, the check valves are normally closed and their associated MOV is also closed and de-energized.
Leakage testing for these valves, including testing requirements, is governed by plant Technical Specification (TS) 3.4.14, RCS Pressure Isolation Valve (PIV)
Leakage. TS Surveillance Requirement (SR) 3.4.14.2 requires that Ginna verify leakage from each SI system hot leg injection line RCS PIV at a prescribed differential pressure. The seat leakage is measured, analyzed, and compared to permissible leakage rates at a frequency prescribed by the Surveillance Frequency Control Program (SFCP), which is 40 months for SR 3.4.14.2.
Due to the lack of test connections, each series pair of check valves (877A/878F and 877B/878H) form one of the two pressure boundaries required to be tested with the second boundary being its associated MOV. Failure of a leakage test of a tested pair would require that both check valves be declared inoperable and in need of rework. Any valve failing the acceptance criteria of TS 3.4.14 shall be declared inoperable and entered into a TS Action in TS Section 3.4.14. Testing of series pairs of check valves in this configuration is allowed by the OM Code, paragraph ISTC-5223, Series Valves in Pairs, and utilizes the guidance found in NUREG-1482, Revision 2, Section 4.1.1, Closure Verification for Series Check Valves without Intermediate Test Connections, which states that testing of the pair of valves is acceptable if the configuration does not require two valves and the safety analysis for such a configuration would credit either of the two valves.
Since the series pairs of check valves 877A/878F and 877B/878H do not have the needed test connections to individually test each valve and since testing of these valves with their adjacent MOVs is specified adequately by TS, it is an undue burden to comply with the OM Code requirements to perform separate leak rate tests. The plant TS establish the maximum permissible leakage rates, test pressure requirements, test frequency requirements, and the required action if the leak rate limit is exceeded. To make modifications to include the proper test connections and perform leak rate testing in accordance with the OM Code would be costly and increase personnel radiation exposure and would not result in a compensating increase in the level of quality and safety.
Proposed Alternative and Basis for Use The licensee stated:
In lieu of the Code-required separate leak rate tests, these series pair check valves will be leak rate tested in accordance with the RCS PIV leak rate testing per TS 3.4.14. The proposed alternative testing will provide reasonable assurance of the valves' operational readiness. Therefore, this alternative to the Code required leakage rate testing of the RCS PIVs is proposed pursuant to 10 CFR 50.55a(z)(2).
NRC Staff Evaluation
The 2012 Edition of the ASME OM Code, paragraph ISTC-3630, requires that Category A valves with a leakage requirement that is not based on a licensees 10 CFR Part 50, Appendix J program be leak-tested at least every 2 years to verify that seat leakage is within acceptable limits. The licensee has proposed an alternative test in lieu of the requirements of ISTC-3630 for two valves that are classified as Category A valves and four valves that are classified as Category A/C valves. Specifically, the licensee proposes to leak-test the valves in accordance with TS 3.4.14, which requires leak testing at a prescribed pressure and at a frequency of 40 months, as prescribed by the licensees Surveillance Frequency Control Program.
Series pair check valves 877A/878F and 877B/878H do not have the needed test connections to individually test each valve. To make modifications to include the proper test connections would be costly and would increase personnel radiation exposure. Due to lack of test connections, each series pair of check valves 877A/878F and 877B/878H form one of the two pressure boundaries required to be tested with the associated MOV forming the second
boundary. NUREG-1482, Revision 2, Guidelines for Inservice Testing at Nuclear Power Plants, Section 4.1.1, references ASME OM Code 2012 Edition, paragraph ISTC-5223, which allows the testing of two series check valves as a closed unit if the valves do not have provisions for individual testing and the plant safety analysis requires closure of only one of the series valves. Therefore, the NRC staff finds that the testing of series check valve pairs as a closed unit is acceptable.
Ginna TS 3.4.14 requires safety injection hot leg valves 877A, 878F, 877B, 878H, 878A, and 878C to be leak-tested at a prescribed differential pressure every 40 months in accordance with the licensees Surveillance Frequency Control Program. Seat leakage is measured, analyzed, and compared to permissible leakage rates. Failure of a leakage test of a tested pair would require both check valves to be declared inoperable and in need of rework. Any valve failing the acceptance criteria is declared inoperable and is entered into a limiting condition for operation according to the TS. This methodology does not meet ISTC-3630 requirements of a 2-year test interval.
When the NRC ordered changes to the Ginna TSs on April 20, 1981 (ADAMS Accession No. ML010540230), the NRC recommended a 40-month test interval and recognized the series pair check valves acting as one component. The NRC staff finds that meeting the ASME OM Code testing frequency would result in additional test time and radiation exposure to plant personnel. The staff concludes that compliance would result in a hardship for the licensee, without a compensating increase in the level of quality and safety and that the proposed alternative provides reasonable assurance that the valves are operationally ready.
The NRC staff notes that a similar alternative request was authorized for the fifth 10-year IST program interval at Ginna by letter dated April 14, 2010 (ADAMS Accession No. ML100890237).
3.2 Licensees Alternative Request VR-01 The request is proposed in accordance with 10 CFR 50.55a(z)(2) for the duration of the sixth 10-year IST program interval at Ginna.
Applicable Code Requirements ASME OM Code 2012 Edition ISTC-5150, Solenoid-Operated Valves, paragraph ISTC-5151, Valve Stroke Testing, states:
(a) Active valves shall have their stroke times measured when exercised in accordance with para. ISTC-3500.
(b) The limiting value(s) of full-stroke time of each valve shall be specified by the Owner.
(c) Stroke time shall be measured to at least the nearest second.
(d) Any abnormality or erratic action shall be recorded (see para.
ISTC-9120), and an evaluation shall be made regarding need for corrective action.
ISTC-5152, Stroke Test Acceptance Criteria, states, in part, Test results shall be compared to reference values established in accordance with para.
ISTC-3300, ISTC-3310, or ISTC-3320.
Affected Components The request applies to the valves in the following table. The licensee stated, These service water (SW) valves open upon an auxiliary feedwater (AFW) pump bearing cooling water supply high strainer differential pressure (DP) to provide cooling water to the driver's bearings.
Valve Description Code Class Category 4324 Turbine-driven Auxiliary Feedwater (TDAFW) Pump SW 3 B Strainer Bypass Solenoid-operated Valve (SOV) 4325 Motor-driven Auxiliary Feedwater (MDAFW) Pump A SW 3 B Strainer Bypass SOV 4326 MDAFW Pump B SW Strainer Bypass SOV 3 B
Reason for Request
The licensee stated:
Pursuant to 10 CFR 50.55a, Codes and Standards, paragraph (z)(2), an alternative to the requirements of ASME OM-2012 Code, paragraphs ISTC-5151 and ISTC-5152 is proposed. The basis of the request is that compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
These SOVs are normally closed rapid acting valves that automatically actuate to the open position on high differential pressure across the supply strainer.
Measurement of stroke times during manual actuation using conventional methods cannot be performed to produce consistent, meaningful or trendable test results. The valves are not provided with control switches to allow for conventional stroke timing methodology. Additionally, there is no remote valve position indication or other positive means to determine valve disc position.
Without concise methods of initiating valve movement or determining when the stroke is completed, it is difficult to obtain repeatable stroke time data to monitor for degradation. It would be necessary to disassemble the respective differential pressure switch in order to control actuation of these valves and as a result of this disassembly, stroke timing during power operation would require rendering these valves inoperable and entering a limiting condition for operation (LCO) from which prompt restoration would not be possible.
These valves are tested on a quarterly frequency during AFW pump testing. This testing includes strainer cleaning, strainer isolation, high differential pressure simulation, verification of valve operation, and flow observation. Failure of these valves to stroke in conjunction with a clogged strainer would result in a lack of pressure at the bearing cooler inlet and a high DP alarm, at which time an Operator would be dispatched to manually trip the respective valve.
This quarterly verification, while not measuring stroke time or monitoring for valve degradation, does provide an indication that each SOV is moving to its safety position by verifying disc movement and is consistent with the guidelines provided in NUREG-1482, Revision 2, Section 4.2.3, Stroke Time for Solenoid-Operated Valves.
Therefore, relief is requested pursuant to 10 CFR 50.55a(z)(2) based on the determination that compliance with the Code SOV testing requirements regarding stroke timing cannot be achieved without resulting in a hardship or unusual difficulty without a compensating increase in the level of quality and safety; and the proposed alternative testing including strainer cleaning, strainer isolation, high differential pressure simulation, verification of valve operation, and flow observation provides reasonable assurance of operational readiness and provides an acceptable level of quality and safety.
Proposed Alternative and Basis for Use The licensee stated:
These valves will be stroke tested during associated AFW pump testing by closing the valve downstream of the strainer. Acceptable valve operation will be based on:
Verifying locally that the valve has de-energized and tripped open.
Verifying the presence of a steady stream of water from the affected floor drain funnel.
Verifying that the associated main control board annunciator alarms.
The proposed alternative testing will accurately reflect obturator position and will provide reasonable assurance of the valves operational readiness. Thus, this alternative to the requirements of the Code-required stroke time testing of the SW SOVs is proposed pursuant to 10 CFR 50.55a(z)(2).
NRC Staff Evaluation
The 2012 Edition of the ASME OM Code, paragraph ISTC-5150, requires that active valve stroke times are measured to at least the nearest second, measurements are compared to the full-stroke time specified by the owner, and any abnormalities shall be evaluated and corrected as necessary. ISTC-5152 requires comparison of the stroke test results to the established stroke test acceptance criteria. The licensee has proposed an alternative test in lieu of these requirements for three AFW SOVs that are classified as Code Class 3, Category B valves.
Specifically, the licensee proposes to test the SOVs quarterly during AFW pump testing to confirm that the SOVs are moving to the required safety position by verifying disc movement.
The design and configuration of the SOVs do not include control switches to allow for conventional stroke timing methodology, and there is no remote valve position indication or other positive means to determine valve disc position. Therefore, measurement of stroke times during manual actuation using conventional methods cannot be performed to produce consistent, meaningful, or trendable test results. In order to measure stroke times during operation at power, the control switches would have to be disassembled, rendering the valves inoperable, which would require the licensee to enter a limiting condition for operation without the ability to promptly restore the SOVs to operable. This would be a hardship for the licensee, without a compensating increase in the level of quality and safety.
The quarterly AFW pump testing includes strainer cleaning, strainer isolation, high differential pressure simulation, verification of valve operation, and flow observation. Verification of valve
operation during the proposed alternative test includes verifying locally that the valve has deenergized and tripped open, verifying the presence of a steady stream of water from the affected floor drain funnel, and verifying the associated main control board annunciator alarms.
This enhanced maintenance approach is consistent with the guidelines provided in NUREG-1482, Revision 2, Section 4.2.3. The staff concludes that the proposed alternative provides reasonable assurance of the valves operational readiness.
The NRC staff notes that a similar alternative request was authorized for the fifth 10-year IST program interval at Ginna in its letter dated December 30, 2009.
3.3 Licensees Alternative Request VR-02 The request is proposed in accordance with 10 CFR 50.55a(z)(2) for the duration of the sixth 10-year IST program interval at Ginna.
Applicable Code Requirements ASME OM Code 2012 Edition Mandatory Appendix I, paragraph I-7310, Class 1 Safety Valves, states, in part:
Tests before maintenance or set-pressure adjustment, or both, shall be performed for subparas. I-7310(a) through (c) in sequence. The remaining shall be performed after maintenance or set-pressure adjustment (f) determination of operation and electrical characteristics of position indicators.
Affected Components The request applies to the valves in the following table. The licensee stated, The Pressurizer Safety Relief Valves provide over-pressurization protection for the Reactor Coolant System (RCS)/Pressurizer.
Component ID Description Code Class Category 434 Pressurizer Safety Relief Valve 1 C 435 Pressurizer Safety Relief Valve 1 C
Reason for Request
The licensee stated:
Pursuant to 10 CFR 50.55a, Codes and Standards, paragraph (z)(2), an alternative to the requirement of ASME OM Code Mandatory Appendix I, subparagraph l-7310(f) is proposed. The basis of the request is that compliance with the specified requirements would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.
These valves are mechanical spring-actuated valves with an externally mounted Linear Voltage Differential Transformer (LVDT) stem position indicator. The position indicator must be removed in order to permit removal of the safety valves each refueling outage for shipment to an off-site vendor for set pressure testing. It would be necessary to intentionally challenge RCS pressure limits to
actuate these safety valves in order to perform position indication testing prior to removal for set pressure testing. Also, if these safety valves were actuated for a position indication test following re-installation, they would again need to be retested to ensure the set pressure has not been adversely affected. This involves increased testing and unnecessary radiation exposure to test personnel and results in a hardship without a compensating increase in the level of quality and safety.
Proposed Alternative and Basis for Use The licensee stated in its letter dated December 13, 2018:
In accordance with plant administrative procedures, channel checks for Pressurizer safety relief valve position indication are performed once per shift and validated by comparison with tailpipe temperature indication. The valves are also simulated to actuate using station calibration procedures. The procedure utilizes movement of the valve's coil (up/down) and verifies position via an alarm in the Control Room. Calibration of these position indicators is governed by plant calibration procedures and is performed on a refueling outage frequency. These procedures verify that the proper clearance is obtained to ensure obturator position is accurately represented and provide reasonable assurance of valve operational readiness. Thus, this alternative to the Code-required testing of the pressurizer safety relief valves is proposed pursuant to 10 CFR 50.55a(z)(2).
NRC Staff Evaluation
The 2012 Edition of the ASME OM Code, paragraph I-7310, requires that tests according to subparagraphs I-7310(a) through (c) for Class 1 safety valves be performed before maintenance or set pressure adjustment, or both. Subparagraph (f) requires determination of operation and electrical characteristics of position indicators after maintenance or set pressure adjustment. The licensee has proposed an alternative test in lieu of these requirements for pressurizer safety relief valves 434 and 435 that are classified as Code Class 1, Category C valves.
These valves are mechanically actuated in response to pressurizer pressure. It would be necessary to intentionally challenge reactor coolant system pressure limits to actuate the valves to perform position indication testing during power operation. Each outage, the position indicator must be removed in order to remove the safety valves and ship them to an offsite vendor for set pressure testing. If position indicator testing is performed after the safety valves have been reinstalled, the valves would need to be retested to ensure the set pressure has not been adversely affected. This would unnecessarily expose the test personnel to radiation and result in a hardship, without a compensating increase in the level of quality and safety.
The licensee proposes an alternative to perform position indicator channel checks and validate the checks by comparison with tailpipe temperature indication during each shift. In addition, the licensee remotely verifies relief valve position indication during refueling outages by simulating actuation using existing calibration procedures. These procedures verify electrical circuitry for position indication to ensure obturator position is accurately represented. The NRC staff concludes that position indicator calibration each outage, combined with position indicator channel checks compared to valve tail pipe temperature each shift, provide reasonable assurance that the indicated position for each safety relief valve is correctly displayed.
The NRC staff notes that a similar alternative request was authorized for the fifth 10-year IST program interval at Ginna by letter dated December 30, 2009 (ADAMS Accession No. ML093570173).
4.0 CONCLUSION
As set forth above, the NRC staff determined that for alternative requests GR-01, VR-01, and VR-02, compliance with the specified requirements would result in hardship or unusual difficulty, without a compensating increase in the level of quality and safety. Accordingly, the NRC staff concludes that the licensee has adequately addressed all the regulatory requirements set forth in 10 CFR 50.55a(z)(2) for this request. Therefore, the NRC staff authorizes the use of these alternative requests for the sixth 10-year IST program interval beginning on January 1, 2020, at Ginna.
All other ASME OM Code requirements for which relief was not specifically requested and approved in the subject request remain applicable.
Principle Contributor: Aaron Mink Date: August 5, 2019