ML20135D466

Safety Evaluation Granting Relief Request RP-01 & Alternative Testing Imposed Per 10CFR50.55a(f)(6)(i) Based on Impracticality of Performing Required Testing

ML20135D466
Person / Time
Site:	LaSalle
Issue date:	12/06/1996
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20135D464	List: ML20135D461 ML20135D466
References
NUDOCS 9612090390
Download: ML20135D466 (5)

Text

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A 42g o* k UNITED STATES j

3 NUCLEAR REGULATORY COMMISSION

's WASHINGTON, D.C. 20606 4001

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SAEEJY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO INSERVICE TESTING PROGRAM REllEF RE00EST RP-01 COMONWEALTH EDIS0N COMFANY LASALLE COUNTY STATION. UNITS 1 AND 2 DOCKET NUMBERS 50-373 AND 50-374

1.0 INTRODUCTION

I The Code of Federal Reaulations,10 CFR 50.55a, requires that inservice testing (IST) of certain American Society of Mechanical Engineers (ASME) Code Class 1, 2, and 3 pumps and valves be performed in accordance with Section XI of the ASME Boiler and Pressure Vessel Code (the Code) and applicable addenda, except where alternatives have been authorized or relief has been requested by the licensee and granted by the Commission pursuant to Sections (a)(3)(1),

(a)(3)(ii), or (f)(6)(1) of 10 CFR 50.55a. In proposing alternatives or requesting relief, the licensee must demonstrate that: (1) the proposed alternatives provide an acceptable level of quality and safety; (2) compliance would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety; or (3) conformance is impractical for its facility. Section 50.55a authorizes the Commission to approve alternatives and to grant relief from ASME Code requirements upon making the necessary  !

l findings. NRC guidance contained in Generic Letter (GL) 89-04, " Guidance on Developing Acceptable Inservice Testing Programs," provides alternatives to the Code requirements determined acceptable to the staff. Alternatives that l conform with the guidance in GL 89-04 may be implemented without additional  !

NRC approval, but are subject to review during inspections. Further guidance was given in Generic Letter 89-04, Supplement 1, and NUREG-1482, " Guidelines l for Inservice Testing at Nuclear Power Plants."

The applicable Code used in the LaSalle Units 1 and 2 third ten-year interval IST program was the 1989 edition of ASME Section XI which specifies that rules for the IST of pumps are stated in ASME/ ANSI Operations and Maintenance Standard, Part 6 (OM-6), " Inservice Testing of Pumps in Light-Water Reactor Power Plants."

2.0 RELIEF RE0 VEST NUMBER RP-01 Relief is requested from the test method requirements of OM-6, Section 5.2(b),

for the Unit I and 2 emergency core cooling system (ECCS) water leg pumps listed below. Relief was granted on an interim basis in an SE dated December 8,1995, in order to investigate installation of flow ENCLOSURE 9612090390 961206 i PDR ADOCK 05000373 P PDR

instrumentation. The licensee has proposed to measure vibration in accordance with OM-6, trend differential pressure and vibration, and use the current monitoring scheme to verify that the ECCS discharge lines are full of water. 1 Flow measurement will not be performed. i 1(2)E22-C003 High Pressure Core Spray Water Leg Pump )

1(2)E21-C002 Low Pressure Core Spray Water Leg Pump 1(2)E12-C003 Residual Heat Removal Water Leg Pump j 2.1 BASIS FOR RELIEF j

The licensee states:

Instrumentation is not installed for measuring flow rates. Pump j flow varies with system operation and system leakage; therefore,  ;

establishing set flow rates for testing purposes is not practical.

The primary purpose of these pumps is to maintain the ECCS pump discharge lines filled to limit the potential for water hammer on ECCS initiation. System modification to provide test measuring locations places undue burden on the utility without demonstrating any increase in the level of plant safety. These pumps are in continuous operation. Pump performance is continuously monitored by a low pressure alarm on each ECCS discharge header.

LaSalle Station monitors the pump for degradation by measuring and j recording pump inlet pressure, discharge pressure, differential

, pressure, and vibration, with the differential pressure and vibration data trended. These measurements are taken quarterly

, and provide satisfactory indication of operational readiness as well as the ability to detect potential degradation. In addition, the main ECCS pumps discharge headers each have a low pressure alarm which continuously monitors the operability of the respective water leg pump. Station Technical Specifications also )

verify operability of the water leg pumps by verifying flow 1 through a high point vent on a monthly basis.

2.2 ALTERNATIVE TEST l The licensee proposes:

Vibration measurement will be obtained under normal operating l conditions and evaluated in accordance with [0M-6]. LaSalle verifies operability of these pumps by pressure maintenance of ECCS discharge lines within allowable limits. In addition, the ,

inlet pressure, discharge pressure, differential pressures are i recorded, with the differential pressure and vibration data trended.

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i 2.3 { VALUATION The Code requires that each water leg pump be tested by establishing a fixed and repeatable hydraulic reference value of either differential pressure or pump flow, establishing the reference value during quarterly testing, and recording the variable reference value and bearing vibration for comparison with Code acceptance criteria. The design of the water leg pumps and their associated ECCS do not enable inservice testing to be readily performed in accordance with the Code. The necessary instrumentation is not installed in the system and a modification would be required for measuring flow and differential pressure. The licensee proposes to monitor the pumps for mechanical degradation only (i.e., vibration monitoring) without monitoring for hydraulic degradation.

The evaluation of this relief request in the December 8,1995, SE stated that i the licensee did not indicate whether portable flow instrumentation had been considered for flow measurement of the ECCS water leg pumps. At least one other plant (Perry) performs inservice testing in accordance with the Code requirements using ultrasonic flow instrumentation. Although the licensee stated in its initial submittal that there is no flow criterion on these pumps that could be used to determine whether the pumps are satisfactorily performing their safety function, IST scceptance criteria does not require testing at the design condition. Therefore, if ultrasonic flow instrumentation could be utilized, acceptance criteria in accordance with the Code requirements could be established.

The NRC has stated that the installation of instrumentation to meet a later edition of the Code is not considered a backfit (see Minutes of the Public Meetings on GL 89-04, Question 105 and Response). However, for the water leg pumps, which are continuously operating pumps, the function is merely to keep the ECCS pump discharge header piping in a filled condition to prevent water hammer upon pump start. The actual output and hydraulic performance of the water leg pumps are not critical to the safety function, as long as the pumps ,

are capable of maintaining the piping full. Alarms alert plant operators to  ;

the condition when the water leg pumps do not maintain the piping full to a i set alarm level. In addition, vibration data will be indicative of levels  !

trending toward unacceptable values and should allow time for the licensee to )

take corrective actions before the pumps fail. While the inservice testing would not be as complete as it would be if the Code requirements were imposed, Section 50.55a does include provisions for impracticalities due to design limitations, as the initial imposition of the Code requirements was subsequent to the design and construction of a number of nuclear plants. The proposed alternative provides a reasonable assurance of operational readiness because i differential pressure and bearing vibration are measured and trended. In 1 addition, alarm indications are present which indicate a degradation in the pressure of the ECCS discharge lines.

The licensee did not discuss whether the pumps are included in a preventative maintenance program because of the impracticalities of full compliance with the inservice testing requirements. If the pumps are not already included in l

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such a program, it is recommended that an assessment of the past operating history of the pumps be performed and a determination be made as to whether or not periodic maintenance is warranted. The granting of the relief is not, however, dependent on the licensee's prior performance of such an assessment.

The monitoring during continuous operation via the level alarms and vibration  ;

measurements will provide adequate assurance of the operational readiness for i operation in an accident mitigation condition.

2.4 CONCLUSION

l The proposed relief request to not perform flow rate testing in accordance l with OM-6, Section 5.2(b), for the ECCS water leg pumps is granted and the '

alternative testing imposed pursuant to 10 CFR 50.55a(f)(6)(1) based on the ,

impracticality of performing the required testing and in consideration of the  ;

burden on the licensee if the Code requirements were imposed. The alternative t testing will provide adequate assurance of the operational readiness of these  !

pumps for performing their safety function of maintaining the ECCS piping full of water to prevent water hammer in the event the ECCS is actuated. 1 Principal Reviewer: J. Colaccino, DE/EMEB l Date: December 6, 1996 l l

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.y December 6, 1996 Ms. Irene Johnson, Acting Manager Nuclear Regulatory Services Commonwealth Edison Company Executive Towers West III l

.1400 Opus Place, Suite 500 Downers Grove, IL 60515

SUBJECT:

EVALUATION OF REQUEST FOR RELIEF R0-01 FOR THE PUMP AND VALVE INSERVICE TESTING PROGRAM - LASALLE COUNTY STATION, UNITS 1 AND 2 (TAC NOS. M96955 AND M96956) 1

Dear Ms. Johnson:

i l

By letter dated October 24, 1996, Commonwealth Edison Company submitted Relief Request RP-01 proposing an alternate testing method for the emergency core cooling system water leg pumps at LaSalle County Station Units 1 and 2. This relief request was previously granted on an interim basis in a safety evaluation (SE) dated December 8, 1995. The staff has reviewed the proposed alternative referenced above against the requirements of Section XI of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code pursuant to paragraph 50.55a of Part 50 to Title 10 of the Code of Federal Reaulations. The basis for the staff's conclusions are contained in l the enclosed safety evaluation. The staff has concluded that relief request ,

RP-01 is granted and the alternative testing imposed pursuant to 10 CFR l 50.55a(f)(6)(1) based on the impracticality of performing the required testing  !

and in consideration of the burden on the licensee if the Code requirements l were imposed. The alternative testing will provide adequate assurance of operational readiness of these pumps. i Sincerely, Original signed by:

Robert A. Capra, Director Project Directorate III-2 Division of Reactor Projects - III/IV i Office of Nuclear Reactor Regulation '

Do:ket Nos. 50-373, 50-374

Enclosure:

Safety Evaluation cc w/ encl: see next page Distribution:

' Docket: File: PDIII-2 R/F J. Roe JWR E. Adensam EGA1 PUBLIC R. Capra D. Skay C. Moore OGC 015B18 ACRS 52E26 M. Dapas, RIII G. Hill (4)

DOCUMENT NAME: LA96955.LTR *See previous concurrence To receive a copy of this document, Indicat Q the box: "C" = Copy without enclosures *E' = Copy with enclosures *N' = No copy 0FFICE PM:PDIII-2 < LAW I.I-2 l D EMEB l D:PDIII-2 lG OCG l NAME DSKAY// wd M TMQJRC W *TSCARBROUGH RCAPRA Roc. *MYOUNG DATE 12/Y/96 17/6/96 11/27/96 12/co/96 12/03/96 0FFICIAL RECORD COPY