ML20031E784

Request for Relief Request P-9 to Defer Performance of Comprehensive Pump Test

ML20031E784
Person / Time
Site:	North Anna
Issue date:	02/19/2020
From:	Markley M NRC/NRR/DORL/LPL2-1
To:	Stoddard D Virginia Electric & Power Co (VEPCO)
Miller G
References
EPID L-2019-LLR-0106
Download: ML20031E784 (8)

Text

February 19, 2020 Mr. Daniel G. Stoddard Senior Vice President and Chief Nuclear Officer Innsbrook Technical Center 5000 Dominion Blvd.

Glen Allen, VA 23060-6711

SUBJECT:

NORTH ANNA POWER STATION, UNIT NO. 1 - RE: REQUEST FOR RELIEF REQUEST P-9 TO DEFER PERFORMANCE OF COMPREHENSIVE PUMP TEST (EPID L-2019-LLR-0106)

Dear Mr. Stoddard:

By letter dated November 18, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19329A285), Virginia Electric Power Company (VEPCO, Dominion Energy Virginia) requested relief from the requirements of the American Society of Mechanical Engineers OM Code, 2004 Edition, to defer performance of the comprehensive pump test for the 1-CH-P-1A Chemical and Volume Control system pump for the North Anna Power Station, Unit No. 1.

Specifically, pursuant to Title 10 of the Code of Federal Regulations (10 CFR) paragraph 50.55a(z)(2), the licensee proposed that there would be hardship or unusual difficulty in performing the test without a compensating increase in level of quality or safety.

The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the subject request and concludes, as set forth in the enclosed safety evaluation, that VEPCO has adequately addressed all of the regulatory requirements set forth in 10 CFR 50.55a(z)(2) and demonstrated that there would be hardship or unusual difficulty in performing the test without a compensating increase in level of quality or safety. Therefore, the NRC staff authorizes Relief Request P-9 for North Anna, Unit 1, until the end of the fourth inservice testing (IST) Program Test interval, which ends on December 14, 2020.

D. Stoddard 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 Inservice Inspector.

If you have any questions, please contact the Project Manager, Ed Miller at 301-415-2481 or via e-mail at Ed.Miller@nrc.gov.

Sincerely,

/RA/

Michael T. Markley, Chief Plant Licensing Branch 2-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-338

Enclosure:

Safety Evaluation cc: Listserv

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION REQUEST FOR RELIEF P-9 TO DEFER COMPREHENSIVE PUMP TEST FOR CHEMICAL AND VOLUME CONTROL SYSTEM PUMP VIRGINIA ELECTRIC POWER COMPANY NORTH ANNA POWER STATION, UNIT NO. 1 DOCKET NO. 50-338

1.0 INTRODUCTION

By letter dated November 18, 2019 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML19329A285), Virginia Electric and Power Company (Dominion Energy Virginia, the licensee) requested U.S. Nuclear Regulatory Commission (NRC) approval of an alternative, pursuant to Title 10, Energy, of the Code of Federal Regulations (10 CFR) 50.55a(z)(2), to the requirements of the American Society of Mechanical Engineers (ASME)

Operation and Maintenance of Nuclear Power Plants, Division 1, OM Code: Section IST (OM Code) associated with the inservice testing (IST) frequency of a pump at the North Anna Power Station (NAPS) Unit 1. In particular, the licensee requested to implement a proposed alternative to specific provisions of the ASME OM Code as incorporated by reference in 10 CFR 50.55a in alternative request P-9 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 pursuant to subparagraph (2), Hardship without a compensating increase in quality and safety, in paragraph (z), Alternatives to codes and standards requirements, of 10 CFR 50.55a. By letter dated January 17, 2020 (ADAMS Accession No. ML20021A005), Dominion Energy Virginia provided supplemental information.

2.0 REGULATORY EVALUATION

Paragraph 10 CFR 50.55a(f)(4), Inservice testing standards requirement for operating plants, states, in part, that throughout the service life of a boiling or pressurized water-cooled nuclear power facility, pumps and valves that are classified as ASME Code Class 1, Class 2, and Class 3 must meet the IST requirements (except design and access provisions) set forth in the ASME OM Code and addenda that become effective subsequent to editions and addenda specified in paragraphs (f)(2) and (3) of this section and that are incorporated by reference in paragraph (a)(1)(iv) of this section, to the extent practical within the limitations of design, geometry, and materials of construction of the components.

Paragraph 10 CFR 50.55a(z) states, in part, that alternatives to the requirements of paragraphs (b) through (h) of this section or portions thereof may be used, when authorized by the NRC, if Enclosure

the licensee demonstrates (1) the proposed alternative would provide an acceptable level of quality and safety; or (2) compliance with the specified requirements of this section would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.

3.0 TECHNICAL EVALUATION

3.1 Requirements and Licensees Proposed Alternative The licensee requested an alternative to the requirements of the ASME OM Code for IST testing frequency for a pump in the alert range.

The ISTB-6200(a), Alert Range, states that if the measured test parameter values fall within the alert range of Table ISTB-5121-1, Table ISTB-5221-1, Table 5321-1, or Table ISTB-5321-2, as applicable, the frequency of testing specified in ISTB-3400 shall be doubled until the cause of the deviation is determined and the condition is corrected.

The licensee requested to use the proposed alternative described below for charging pump 1-CH-P-1A. The pump is ASME Boiler and Pressure Vessel Code (BPV Code), Section III, Class 2, and is classified as a Group A pump. The licensee requested that the proposed alternative request be authorized through the remainder of the NAPS Unit 1 Fourth 10-year IST program interval, which is scheduled to end on December 14, 2020.

The ASME OM Code of record for NAPS Unit 1 is the 2004 Edition with no Addenda.

3.2 Reason for the Request The licensee states, in part, that:

The Unit 1, 1A charging pump (1-CH-P-1A) is a horizontal, eleven-stage centrifugal pump, with a 900 HP, 1800 rpm motor that drives the pump at 4846 rpm through a speed increasing gearbox.

This centrifugal pump supplies high pressure borated water to the reactor coolant system following a safety injection signal and provides normal charging to the reactor coolant system.

One of the seven vibration points recently exceeded alert criteria during performance of the Comprehensive Pump Test (CPT) scheduled in conjunction with the Fall 2019 Unit 1 refueling outage. Vibration monitoring is a component of the CPT that is performed at a frequency of every refueling outage (18 months) as required by ISTB-3400. Per ISTB-6200, since the vibration measurement falls within the alert range, a CPT is required to be performed every 9 months until the condition is corrected. Performance of the CPT required that the Chemical and Volume Control System (CVCS) 1A charging pump achieve the required reference flow rate. This can only be achieved with the reactor head removed from the reactor vessel, allowing flow to be directed into

the reactor cavity. Therefore, this test cannot be performed during normal power operations.

The proposed relief would permit continued performance monitoring of the Unit 1, 1A charging pump (1-CH-P-1A) by performing quarterly Group A tests in lieu of performing the CPT at the increased test frequency of every 9 months. The Group A test can be performed safely while the associated unit is operational.

This would eliminate the need to unnecessarily shutdown the plant and reach Mode 6 in order to perform the CPT. This relief will only apply to ISTB-6200 requirements as they relate to doubling of the CPT test frequency. With subsequent Group A testing, if any measured IST parameter exceeds the alert criteria, the requirements of ISTB-6200(a) will be followed (i.e. the Group A test would be performed at the prescribed increased frequency).

3.3 Proposed Alternative The licensee submitted the following proposed alternative:

Dominion is proposing to perform the quarterly Group A test in lieu of the CPT with the associated Unit operational as an alternative to shutting down the plant, establishing Mode 6 conditions, and removing the reactor vessel head in order to perform the CPT required by ISTB-6200(a).

3.4 NRC Staff Evaluation Paragraph (a) in ISTB-6200 of the ASME OM Code specifies the testing frequency in ISTB-3400 to be doubled for pumps whose measured test parameter values fall within the alert range of the applicable table (Table ISTB-5121-1, in this case).

This IST requirement, together with the other IST requirements in the ASME OM Code as incorporated by reference in 10 CFR 50.55a, provides reasonable assurance of the operational readiness of the safety-related pumps in NAPS Unit 1. The purpose of this increased CPT testing frequency for pumps in the alert range is to monitor for additional performance degradation until the cause of the deviation is determined, and the condition is corrected. The performance of pump 1-CH-P-1A can be tracked and trended from testing performed at flow rates other than those specified for the CPT. The reference point flow rate values for the CPT are established in accordance with ISTB-3000 within +/-20% of pump design flow, or at the highest practicable flow rate for the Group A test if the CPT flow rate cannot be achieved. The highest practical Group A test reference point flow rate is 162 gallons per minute (gpm), as allowed by NRC-approved relief request P-8 (ADAMS Accession No. ML102460223).

Seven vibration monitoring points have been established in accordance with Subsection ISTB of the ASME OM Code. The pump vibration reference values do not differ significantly when comparing the Group A and CPT values as shown in Table 1 of the licensees submittal. The vibration point that is in the alert range, Thrust Bearing Vertical, reflects a small difference when comparing test reference values. As such, the Group A test provides a method to monitor pump vibration parameters comparable to that of the CPT without the need to shut down the plant.

The licensee outlined the maintenance and diagnostic history of 1-CH-P-1A dating back to a rebuild in August 2012. The licensee contracted with subject matter experts and a pump vendor for their recommendations on the vibration conditions. The licensee stated that there was no

evidence of natural frequency, coupling misalignment, cocked bearings, or bowed rotor involvement in the elevated vibration conditions. New baseline vibration reference values were established for the Group A test subsequent to an inspection and minor adjustment of the pump gearbox high speed shaft and pump shaft coupling, as the vibration levels observed during the performance of the Group A test (July 13, 2017) remained relatively unchanged.

During the CPT on September 22, 2019, measured vibrations at the thrust bearing vertical axis reached 0.357 inches per second (ips), exceeding the ASME OM Code prescribed alert range absolute criteria of 0.325 ips, which was the first instance of such an exceedance during the CPT following speed increaser maintenance in 2012. The required action range for this vibration is > 0.7 ips.

The licensee stated that vibration data appear correlated between the CPT and Group A Test, and the vibrations have been reasonably consistent, albeit elevated, since 2012. Using the more detailed plots ov the vibration data in their January 17, 2020, supplement, the NRC staff was able to confirm that the vibration data are correlated between the CPT and Group A Test.

The licensee also provided additional information in its submittal supporting the capability of pump 1-CH-P-1A to perform its safety function:

Oil samples from the pump bearing reservoir do not present evidence of degradation (such as no wear particles, unacceptable viscosity, or change in additive content) since the initial increase of elevated vibrations in 2012.

Hydraulic performance data recorded during the September 22, 2019, CPT remains aligned with the operating curve with no notable decrease in flow or discharge pressure.

The maximum analyzed design-basis accident required flow is 594.4 gpm at 2961.2 feet Total Developed Head (ft TDH). Since 2012, total run time for this pump has been 2800 hours0.0324 days <br />0.778 hours <br />0.00463 weeks <br />0.00107 months <br /> - 3900 hours0.0451 days <br />1.083 hours <br />0.00645 weeks <br />0.00148 months <br /> each year, and although vibrations have remained elevated, the pump hydraulic parameters do not show evidence of degrading performance.

Although the pump vibrations are elevated, the NRC staff finds that there is reasonable assurance that pump 1-CH-P-1A will continue to meet its prescribed safety function and flow requirements with the thrust bearing vertical vibration measurement in the alert range, based on the absence of degrading pump performance, as discussed above.

The licensees request to perform quarterly Group A tests of pump 1-CH-P-1A in lieu of the CPT with the associated Unit operational is reasonable because (1) the vibration data is correlated between the CPT and Group A Test, (2) the licensee will monitor pump vibrations through the performance of the Group A test, and (3) the pump hydraulic parameters have not indicated any significant degradation in the hydraulic performance of the pump. Therefore, the NRC staff finds the licensees proposed alternative to provide reasonable assurance of the operational readiness of pump 1-CH-P-1A until the end of the Fourth IST Program interval (December 14, 2020).

4.0 CONCLUSION

Based on the above, the NRC staff concludes that compliance with the ASME OM Code corrective action requirement of ISTB-6200(a) would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety, and that the licensees

proposed alternative P-9 provides an acceptable level of quality and safety. Therefore, the staff authorizes the use of the alternative request P-9 to the specific ISTB testing frequency for the CPT for the Unit 1, 1A charging pump (1-CH-P-1A) until the end of the Fourth IST Program interval, which is scheduled to end on December 14, 2020.

All other ASME OM Code requirements as incorporated by reference in 10 CFR 50.55a for which relief from, or an alternative to, was not specifically requested and approved in this subject request remain applicable.

Principal Contributor: N. Hansing, NRR Date: February 19, 2020

ML20031E784 *Via SE Input OFFICE NRR/DORL/LPL2-1/PM NRR/DORL/LPL2-1/LA NRR/DEX/EMIB/BC* NRR/DORL/LPL2-1/BC NAME GEMiller KGoldstein TScarbrough MMarkley DATE 02/07/2020 02/12/2020 02/07/2020 02/19/2020