ML20216E177

Safety Evaluation Accepting Relief Request 98-01 for Catawba Nuclear Station Units 1 & 2 from Requirements of ASME Boiler & PV Code for Second 10-year Interval Program for Inservice Testing of Pumps & Valves

ML20216E177
Person / Time
Site:	Catawba
Issue date:	04/13/1998
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20216E102	List: ML20216E097 ML20216E177
References
NUDOCS 9804160121
Download: ML20216E177 (5)

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j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 30866 0001

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION l

OF THE SECOND 10-YEAR INTERVAL INSERVICE TESTING PROGRAM j

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REQUESTS FOR RELIEF NO. 98-01 DUKE ENERGY CORPORATION l

CATAWBA NUCLEAR STATION. UNITS 1 AND 2 DOCKET NOS. 50-413 AND 50-414

1.0 INTRODUCTION

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Title 10 of the Code of Federal Reaulations (10 CFR) Section 50.55a, requires that inservice testing (IST) of certain American Society of Mechanical Engineers (ASME) Code Class 1,2, j

and 3 pumps and valves be performed in accordance with Section XI of the ASME Boiler and j

Pressure Vessel Code (ASME Code) and applicable addenda, except where relief has been J

requested and granted or proposed alternatives have been authorized by the Commission pursuant to 10 CFR 50.55a (f)(6)(i), (a)(3)(i), or (a)(3)(ii). In order to obtain authorization or relief, the licensee must dernonstrate that: (1) conformance is impractical for its facility; (2) the proposed altemative provides an acceptable level of quality and safety; or (3) compliance would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety. Guidance related to the development and implementation of IST programs is given in Generic Letter (GL) 89-04, " Guidance on Developing Acceptable Inservice Testing Programs," issued April 3,1989, and its Supplement 1, issued April 4,1995. Also, see NUREG-1482, " Guidelines for Inservice Testing at Nuclear Power Phnts," which was promulgated by GL 89-04, Supplement 1.

Section 50.55a authorizes the Commission to grant relief from ASME Code requirements or to approve proposed alternatives upon making the necessary findings. Pursuant to 50.55a(f)(6)(i),

the Commission may grant relief and impose attemative requirements as it determines are authorized by law and will not endanger life or property or the common defense and security and is otherwise in the public interest giving due consideration to the burden upon the licensee that could result if the requirements were imposed on the facility.

i By letter dated January 22,1998, Duke Energy Corporation (the licensee) submitted Relief l

Request No. 98-01 for the Catawba Nuclear Station, Units 1 and 2, second 10-year interval program for inservice testing of pumps and valves. The licensee's IST program covers the second 10-year IST intervals that began December 29,1995, for both units. The IST program Enclosure 9804160121 980413 i

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is based on the requirements of the 198g Edition,Section XI, of the ASME Code, which by reference incorporates Part 6, " Inservice Testing of Pumps in Light-Water Reactor Power Plants," and Part 10 " Inservice Testing of Valves in Light-Water Reactor Power Plants," of the ASME Operations and Maintenance Standard OM-1988.

2.0 DISCUSSION AND EVALUATION 2.1 Diesel Generator Fuel Oil System Valves 1FD34, 2FD34,1FD74, and 2FD74 The licensee requested relief from the requirements of OM-1, paragraph 1.3.4.1, which specifies testing requirements for Class 2 and 3 pressure relief devices. Specifically, the licensee requested relief from bench testing the diesel generator engine retum header relief valves 1FD34,2FD34,1FD74, and 2FD74.

The licensee states:

The subject valves perform a dual function of regulating fuel pressure to the diesel generator engine and providing overpressure protection of the fuel oil retum line from the main circulation header. Each valve is physically located above its corresponding diesel generator fuel oil day tank. The valves are set to regulate fuel oil pressure at a maximum value of 40 psig. With the diesel generator running, the valve relief pressure setpoint maintains a backpressure of

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40 psig on the main circulation header. The valve will lift to relieve pressure in excess of 40 psig, thereby fulfilling both its regulation and overpiassure protection functions. They are 1-inch valves manufactured by Fultlo Specialties Company.

OM-1 requires that relief valves in applications such as this be periodically removed from service and bench tested using the respective fluid medium for the valve (in this case, fuel oil).

The licensee is seeking relief from OM-1, paragraph 1.3.4.1, Pressure Relief Valves. This paragraph specifies testing requirements for Class 2 and 3 pressure relief devices. The licensee is requesting relief from the requirement to bench test the subject valves, stating:

Catawba does not presently have a test bench to allow testing of the subject valves. Procurement of a separate test bench for these four valves would be impractical and would not provide sny additional assurance of the valves' ability to perform their design function. This ability can be successfully demonstrated by attemate testing as discussed below.

' The licensee proposes:

Diesel generator fuel oil pressure will be verified monthly during the diesel

' generator performance test. The monthly test, conducted according to procedures PT/1&2/A/4350/02A&B, D/G Operability Test, for Units 1 and 2 and

i i diesel generators A 'and B, respectively, verifies both the pressure regulating and overpressure protection functions of the subject valves. These procedures perform the monthly diesel generator run during which fuel oil recirculation header pressure is monitored. Procedure MP/0/A/7700/21, Diesel Engine Fuel Oil Back Pressure Relief Valve Corrective Maintenance, is performed after outage diesel generator maintenance to adjust the subject valves to the required i

40 psig backpressure.

l Verification of the subject valve functions (pressure regulating and overpressure i

protection) as part of the diesel generator performance test will provide complete assurance of the valves' ability to perform as designed. The valves will be tested -

under the actual conditions for which they are expected to operate; hence, their system functions can be directly verified. No adverse impact upon public health and safety will be generated from a radiological or other standpoint.

Contrary to what is indicated in the licensee's relief request, bench testing is not a Code requirement. OM-1, paragraph 1.3.1.3, states that "it is not a requirement of this part that valves or accessories be removed from their installed position or disassembled." Therefore, the staff concludes that relief from bench testing is not required. if the proposal to test the valves in place as part of the monthly diesel generator performance test is not consistent with OM-1 requirements, the licensee should refer to the NRC's guidance in NUREG-1482, Section 3.4, " Skid-Mounted Components and Components Subassemblies," and submit a relief request with sufficient detaiis relative to attemative testing, i.e., testing the valves in place.

i 2.2 Diesel Generator Engine Starting Air Check Valves 1/2VG5&7,1/2VG6&8,1/2VG49&51, and 1/2VG50&52 i

L The licensee requested relief from the requirements of OM-10, paragraph 4.3.2.2, which

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specifies that each valve shall be exercised or examined in a manner that verifies obturator travel to the required position. The licensee a!so requested relief from the requirement to individually test diesel generator starting air dryer discharge check valves 1/2VG5&7, 1/2VG6&8,1/2VG49&51, and 1/2VG50&52.

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The licensee states:

Each valve in the above-listed pair works together with its in-series counterpart i

to prevent depressurization of the respective normally-charged diesel generator i

engine starting air tank. Each valve opens as necessary during normal operation to recharge the tank when the respective diesel generator is not in operation.

Each valve must open during diesel generator operation to recharge the tank, if necessary. These valves are 1-inch Kerotest soft-seat check valves. They are located between their respective air dryer and the starting air tank.

These valves are required to be full-stroked exercised every three months to the position required to fulfill their function.

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4 ASME Code requirements dictate that each valve in the above-described pairs of valves be separately tested and be determined capable of fulfilling its design function. ASME/ ANSI OM-1987 Edition, Part 10, including OMa-1988, paragraph 4.3.2.2, specifies that each valve shall be exercised or examined in a manner which verifies obturator travel to the required position. Due to the series system valve arrangement, Catawba has no means to separately verify each valve's ability to close. Catawba therefore requests relief from the ASME Code requirement specifying that each valve be individually tested.

The licensee proposes:(as stated) i Valve pairs (1/2VG5&7,1/2VG6&8,1/2VG49&51, and 1/2VG50&52) will be tested at least quarterly. This test will be conducted according to procedures PT/1&2/A/4200/077, VG Valve Inservice Test, for Units 1 and 2, respectively.

The purpose of this test is to check the backleakage through each valve pair with

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the diesel generator secured. A starting air tank pressure decrease of greater j

than 5 psig in a 10-minute period would indicate excessive leakage through the valve pair and would require corrective action upon detection of such a condition.

Both valves in the affected pair will be inspected for degradation and repaired as appropriate should such a condition be detected.

Testing of the above described valve pairs as indicated above will verify the ability of the pair to perform its design function. Both valves in each pair are not i

required to be capable of functioning separately in order for the diesel generator to function property, No adverse impact upon the health and safety of the public, either from radiological consequences or otherwise, will be created as a result of the proposed attemative testing.

i The check valves 1/2VG5&7,1/2VG6&8,1/2VG49&51, and 1/2VG50&52 (two in series) have a -

l safety function to prevent a depressurization of the normally charged diesel generator engine starting air tank and to open as necessary to recharge the tank when the diesel generator is not i

in operation. The Code requires valves performing safety functions to be stroked to the position (s) required for the valves to perform those functions; however, the licensee stated that

' the current system design does not allow testing to ensure both valves in series will close.

The guidance in NUREG-1482, Section 4.1.1, addresses testing series check valve pairs as a unit. If only one of the redundant series valves is credited in the safety analysis (that is, the other could be removed without creating an unreviewed safety question or creating a conflict l

with regulatory or license requirements), then verification that the group of valves is capable of l'

performing the required function should be acceptable for inservice testing. On this basis, all group check valves must be included in the IST program and be subject to equivalent quality f-assurance criteria. Testing is required during each quarter or at an extended interval in accordance with the Code. If the licensee finds indication that the closure capability of the group of valves is questionable, all valves in the group must be declared inoperable and corrective actions taken for all valves, as necessary, before being returned to service.

Inservice testing of series valves as a pair cannot be used as an attemate means of verifying leak-tightness (Category A/C valves). Inservice testing to verify the closure of serics check

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l v valves as a pair does not enable the licensee to verify the operational readiness of each component as intended in the Code because this testing method would not detect if one valve of the pair failed open.

The iicensee's proposed attemative testing conforms with the guidance provided in NUREG-1482, Section 4.1.1. Under these conditions, the requirements of the Code are i

impractical as the system design does not allow individual testing to ensure the series check l

valves will close imposition of the Code would require redesign of the system or replacement of the components to allow individual valve testing. The staff finds that the proposed attemative testing provides reasonable assurance of operational readiness conssitent with NUREG-1482,

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Section 4.1.1.

l The staff determine that the licensee's proposal provides reasonable assurance of operational readiness, and that the requirements of the Code are impractical. Pursuant to 10 CFR j

50.55a(f)(6)(i), the requested altemative with regard to testing the diesel generator starting air dryer discharge check valves, is granted. The relief granted is authorized by law and will not endanger life or property or the commori defense and security, and is otherwise in the public interest giving due consideration to the burden that could result if the requirements are imposed on the facility.

Principal Contributor: K. Dempsey Date:

April 13, 1998 l

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