ML20199D025

SER Accepting Relief Requests for Inservice Testing Program for Pumps & Valves

ML20199D025
Person / Time
Site:	South Texas
Issue date:	11/17/1997
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20199C934	List: ML20199C933 ML20199D025
References
NUDOCS 9711200227
Download: ML20199D025 (9)

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.. / t UNITED STATES

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NUCLFAR REGULATORY COMMISSION

, WASNINGTON. D.C. enmaa nnnt g...../

SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO INSERVICE TESTING PROGRAM RE0 VESTS FOR RELIEF HOUSTON LIGHTING & POWER COMPANY CITY PUBLIC SERVICE BOARD OF SAN ANTONIO CENTRAL POWER AND LIGHT COMPANY CITY OF AUSTIN. TEXAS 10VTH TEXAS PROJECT. UNITS 1 AND 2 DOCKET NOS. 50-498 AND 50-499

1.0 INTRODUCTION

The Code of Federal Regulations, 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 relief has been 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 demonstrate that: (1) compliance is impractical for its facility; (2) the proposed alternative provides an acceptable level of quality and safety; or (3) compliance would result in a hardship or unusual difficulty ,

without a compensating increase in the level of quality and safety. Section 50.55a(f)(4)(iv) provides that inservice tests of pumps and valves may meet the requirements set forth in subsequent editions and addenda that are -

incorporated by reference in 10 CFR 50.55a(b), subject to the limitations and modifications listed, and subject to Commission approval. Nuclear Regulatory Commission (NRC) guidance contained in Generic Letter (GL) 89-04, "Cutdance on Developing Acceptable Inservice Testing Programs," provided alternatives to the Code requirements determined to be acceptable to the staff and authorized the use of the alternatives in Positions 1, 2, 6, 7, 9, and 10 provided the licensee follows the quidance delineated in the applicable position. When an alternative is proposed which is in accordance with GL 89-04 guidance and is documented in the IST program, no further evaluation is required; however, implementation of the alternative is subject to NRC inspection.

Section 50.55a authorizes the Commission to grant relief from ASME Code requirements or to approve proposed alternatWes upon making the necessary findings. The NRC staff's findings with respect to granting or not g, anting the relief requested or authorizing the proposed alternative as part of the licensee's IST program are contained in this safety evaluation (SE).

9711200227 971117 PDR ADOCK 05000498 P PDR ,

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i 2.0 llACKGROUND The IST programs at the South Texas Project, Units 1 and 2 (STP), were developed to the requirements of the 1983 Edition, with addenda through the Summer 1983 Addenda, of Section XI of the ASME Code. Houston Lighting &

-Pcwer, licensee for the station, submitted Valve Reitef Requests RR Revision 1, RN 53 - Revision 1 RR-55 and RR-56 for Unit 1, and RR Revision 1, RR Revision 1, RR-51 and RR-52 for Unit 2 in its letter dated April 16, 1996. Relief Requests RR-56 for Unit I and RR-52 for Unit 2 were eliminated by the supplemental letter and are not evaluated herein.

The IST submittals relate to a recent change to the technical specifications which allows an outage on each standay diesel generator of sufficient (TSs)h each operating cycle to perform maintenance normally performed during a Iengt refueling outage. Approval of the relief requests will allow the licensee to <

perform IST in conjunction with the maintenance, minimizing the overall unavailt.bi'ity of the diesel generators.- The NRC issued Amendment Nos. 85 and 72 to the operating Ilcenses for the Units 1 and 2, respectively, amending the TSs ass)ciated with the allowable outage times for the standby diesel generators, in a letter dated October 31, 1996. The amendments allow an outage time for a standby diesel gerarator of 14 days and an outage time for an7essential of days. The cooling water approval (ECW) cf the loop and extended an essential allowed chillrelate outage times water (d, inECHW) loop part, to the additional redundancy provided by the three train configuration of these systems.

Additionally, the su>plemental letter included revisions to RR-34 (Unit 1)

.nd RR-31 (Unit 2) w11ch relate to disassembly and inspection of safety injection (SI) pump suction check valves during the 7-day SI system allowed outage time while the unit is at power operating conditions, or during refueling outages. This 7-day allowed outage time was approved by the NRC in Amendment Nos. 59 and 47, issued on February 17, 1994.

3.0 P i REllEF REQUESTS Based on the completion of the NRC's review and approval of TS amendments related to the IST relief requests, an evaluation of each of the relief requests is provided below.

3.1 Relief Reauests RR-34. Rev.1 (Unit 1) and RR-31. Rev.1 (Unit 2)

Those requests concern SI pump suction check valves, SI-2A, -2B, and -20. The ASME Code,Section XI, Paragraph IWV-3521 (Test frequency), requires that these valves be exercised cuarterly, or during cold shutdewns if exercising is impractical during power operations. The licensee requested relief from these exercising requirements. The licensee has pro)osed to establish a grouping of valves and to use a sam)1ing plan for disassem)1ing and inspecting one valve per group on an 18-mont.1 interval during any plant mode.

i 3.1.1 Licenste's Basis for Relief The licensee states the following:

Basis for Relief (Ocen Exercise)

These check valves can only be exercised (full stroke) by simulating LOCA [ loss-of-coolant accident) conditions (pumping into the RCS

[ reactor coolant system, with RCS at zero or very low pressure) in order to get full pump flows.

Basis for relief (Closed Exercise)

1) Closure of these check valves cannot be verified by non-intrusive means. There are no external position indicators on these valves and due to the soft closure of these valves (due to pump coastdown) acoustic methods are not conclusive. In addition, magnetic methods are also not conclusive.

2) Draindown required toofperform a portiondisassembly of the safetyandinjection [SI)he-fvalves.

inspection t system is

3) Disassembly and inspection can only be accomplished during the 7 day Safety Injection System LCO Limiting Condition for Operation) window or during refueli[ng outages.

4) local leakage rate testing [LLRT) of other SI valves and other maintenance activities are now being conducted during the 7 day Safety Injection System LC0 windows. Conducting the disassembly and inspection of these check valves in conjunction with LLRTs or other maintenance activities would accomplish the following:-

a) Increase the availability of the Safety Injection System during refueling outages which would lower the overall risk during the outages. The online risk should not be increased ,

if performed during the A0T [ allowed outage time) window since the Safety Injection Train will already be removed from service for LLRTs or other maintenance, b) Radwaste should te reduced u the inspections will be performed with ot ser draindawn work during the LCO week, c) There will be a reduction in outage manpower and resource requirements for both maintenance and operations personnel. -

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4 d) A reduction in radiation exposure should be realized because  !

personnel will have to perform drain and fill operations

[only)once.  ;

3.1.2 Alternative Testina The licensee proposes:

Alternative Testina (Onen Exercise) l These check valves will be required to be exercised Cpartial stroke at least once every three (3) months by runnsng normal) recirculation flows; and exercised (full stroke) eac) pumps at

- refueling outage by injecting into the RCS with the vessel head off using the appropriate pump (s) at full flow.

• Alternative lastina (Closed Exercise)

At least one check valve from the sample group will be verified operable by disassembly and inspection on a nominal refueling cycle frequency of  :

18 months (i 25%). This will not result in a reduction in the number of inspections performed over the life of the plant. If a generic failurit occurs, a plan of action for inspecting the remaining valves will be developed utilizing the Condition Reporting Process and the guidance provided in GL 91-lL. This plan of action will take into account the  ;

potential failure modes [ including connon-mode failures and their associated plant insacts and will be implemented in a t< me frame commensurate with tteir safety significance. This will ensure that all .

check valves In this sample group are inspected within six years as '

required by GL 89-04, Position 2. Approval of this Relief Request will not precluoe STP from >erforming these ins)ections during refueling outages should some et1er scope of work ma(e it necessary to drain a train of $1.

3.1.3 Evaluation hercise to Verify Opening Capa6 fifty: The proposed alternative for the opening saft.ty function confoms with the Code requirements for partini stroke exercising each quarter. The extension of the fuli-stroke 2xercise to each -

refueling outage is necessary because full stroke testing every three months is impractical (1) due to the SI system design limitations to achieve full flow-through the valves during any mode of plant operation other than during the time period that the reactor vessel head is removed during refueling outages, and (2) due to the lack of position indication to verify obturator l travel at less than full flow conditions. To impose testing at any other o , condition would be a burden on.the licensee involving modifications (1) to the

. SI system to achieve'. full flow at conditions other than during the time period that the reactor' vessel head _ is removed, or (2) to the valves to install external' position indicators such that_ full stroke can be verified at partial l

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system flow conditions, in addition to the flow test during the plant condition with the reactor vessel head removed, the disassembly and inspection for riosurs verification gives a means of monitoring the valve it.ternals for '

degrading conditions. Therefore, the extension for the full-stroke o>ening oC the valve is acceptable based on the impracticalities of performing tie flow test at other plant conditions and the design limitations in that no position indicators are installed on the valves. The alternative testing will give adequate assurance of the operational readiness of the valves to open.

Exercise to Verify closure Capability: The use of a sampiing program for disassembly and inspection of check valves where testing is impractical was indicated as an acceptable alternative in Position 2 of Attachment I to GL 89-04. Testing of these check valves is impractical because (1) there are no external position Indicators on these valves, and (2) non-intrusive test methods are not conclusive. To impose testing each quarter would be a burden on the licensee involving modifications to the valves to install external position indicators.

The licensee's proposed schedule of nominally every 18 months differs from tie guidance in GL 89-04, Position 2, in that the STP disassembly and inspection could be performed in a plant mode other than refueling. The main concern is that a common-cause failure might be identified for the group of valves durinj an inspection while the plant is in a power operating condition. If this occurs, the other valves may be declared inoperable and a plant shutdown may be required. The licensee indicated its intent to follow the provisions of GL 91-18, and therefore, would determine the necessary corrective actions ano develop a 31an to address the common-cause failure on a case-by-case basis.

As such, tie proposed alternative will arovide assurance of valve operability for those valves thet are included in tie disassembly and inspection program.

3.1.4 Conclusion Relief to perform dissembly and inspect'on of the safety injection pump suction check valves SI-2A, -28, and -2L during any plant mode, but at nominal 18-month intervals, is granted and the alternatives described above imposed pursuant to 10 CFR 50.55a(f)(6)(i) based on the impracticality of performing the Code test frequency requirements for open and closure verification, and in consideration of the burden on the licensee if the Code requirements were iniposed on the facility. The proposed alternative testing frequency provides a reasonable assurance of operational readiness because: 1) disassembly and inspection of the SI check valves will be conducted largely in accordance with GL 89-04, Position 2; 2) if a common-cause failure is identified during a plant moda other than refueling, the necessary corrective actions and plans will be developed to address the common-cause failure on a case-by-case basis per GL 91-18; and 3) the proposed test interval is identical to the interval in Position 2, making the licensee's proposed alternative to the test frequency in Position 2 acceptable.

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3.2 Valve Relief Recuests RR-53. Rev.1 (Unit 1) and RR-49. Rev.1 (Unit 2)

These requests concern check valvas D0-0056, -0062, -0068, and D0-126

-127, -128 in the diesel generator fuel oli storage and transfer system. The ASME Code,Section XI, Paragraph .<V-3521 (Test Frequency), requires that these valves be exercised quarterly, or during cold shutdowns if exercising is impractical during power operations. The licensee reqcested relief from these e.v.ercising requirements. The licensee has proposed to closure test each set of check valves on a norminal refueling cycle frequenc;' of 18 months (* 25%).

3.2.1 Licensee's Basis for Relief The licensee states:

1) The valves are currently tested at refueling outages because the Standby Diesel Generators are required to be out of service to perform these inservice tests and previous Ivchnical Specification (TS) Limiting Condition for Operation (LCO) Allowed Outage Times (A0T) were not sufficient to conduct the inservice test and perform a disassembly and inspection, if warranted.

2) The South Texas Project has a A0T approved on the Standby Diesel Generators which provides sufficient time to allow these inservice tests to be performed during the A0T window.

The A0T will permit a 14 day Standby Diesel Generator outage per TS 3.8.1.1 for each Standby Diesel Generator.

3) These check valves are operating in diesel oil which is a clean lubricating medium. STP has been testing these valves since 1991 and there have been no generic failures identified.

3.2.2 Alternative Testina The licensee proposes:

Each set of these check valves will be verified operable by back-seating the valves to verify they have closed on a nominal refueling cycle frequency of 18 months (i 25%). This will not result in a reduction in the number of inspections performed over the life of tha plant. This process requires draining of 50 to 100 gallons of diesel fuel per. test and inoperability of the associated diesel. The applicability of various non-intrusive testing technicues are being evaluated for these small lift check valves. Shoulc an acce) table technique be identified, it will be substituted for the metiod described above. This testing will be performed in conjunctica with a Standby Diesel Generator A0T outage or refueling outago. If any check valve is found inopert.ble, it shall be disassembled to determine the cause. If a

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.o generic failure occurs, a plan of action for inspecting the remaining valves in the sampl* group will be developed utilizing the condition Reporting Process at:d the guidance provided in GL 91-18. This plan of action will take into account the potential failure modes (including common-mode failures] and their associated plant impacts and will be implemented in a time frame commensurate with their safety significance.

3.2.3 Evaluation The Code requires that these check valves be exercised to their safety position quarterly or during cold shutdowns. In order to test these valves in accordance with the Code reqJirements, the diesel generator must be out of service and 50 to 100 gallonn of fuel oil must be drained from the diesel generator fuel oil storage and transfer system. Compliance with the Code test frequency requirements would result in a hardship on the licensee without a compensating increase in safety since the licensee pro)oses other means to provide assurance of valve opurability. The licensee las aroposed to perform the Code-testing during any mede of plant operation when tie associated diesel generator is removed from service at a time interval consistent with a refueling outage schedule. The pro)osed testing )rovides a reasonable assurance of operational readinoss )ecause: 1) t1e 1989 edition of ASME Section XI which is currently endorsed by the NRC in 10 CFR 50.55a allows deferral of valve testing to refueling outages for testing which is impractical to perform quarterly or during cold shutdowns; and 2) testing during any mode of plant operation while maintaining a refueling outage interval between te.;1s provides a test interval which is consistent with the test interval in the 1989 edition of ASME Section XI. In addition, the proposed alternative testing minimizes the out-of-service time of safety-

. related equipment.

3.2.4 Conclusj.nn The proposed alternative to the Code test frequency requirements for the diesel generator fuel oil storage and transfer check valve:; D0-0056, -0062,

-0068 and D0-126 -127, -128 is authorized pursuant to 10 CFR 50.55a(a)(3)(ii) based on the determination that compliance with the Code test frequency requirements results in a hardship without a compensating increase in the level of quality and safety.

3.3 Valve Relief Recuests RR-55 gait 1) and RR-51 (Unit 2)

These requests concern check valves EW-0370A, -0370B, -0370C and EW-403,

-404, -405 in the essential cooling water (ECW) system. The ASME Code,Section XI, Paragraph IW7-3521 (Tent Frequency), requires that these valves be exercised quarterly, or during cold shutdowns 1f exercising is impractical during power operations. The licersee requested relief from these exercising requirements. The licensee has proposed to establish a grouping of valves and to use a sampling plan for disassembling and inspecting one valve per group on an 18-month interval during any plant mode.

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3.3.1 Licensee's Basis for Relief The licensee states:

1) The valves are currently disassembled and inspected during l refueling outages in accordance with GL 89-04, Position 2,

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because the inspection removes a train of ECW from service >

which also removes the associated trains of Component Cooling Water, Residual Heat Removal, Essential Chilled Water, Spent Fuel Pool Cooling, and Standby Diesel Generators from service.

Previous Technical Specification (TS) Limiting Condition for Operating to conduct the(LCO) inservice test at power. Allowed Outage Times (A0T) wer

2) The South Texas Project has A0Ts which will provide sufficient time to allow these inservice tests to be performed during the A0T window.

3) Allowing testing during these spe:ific system outage windows will ensure component operability while minimizing safety system unavailability.

4) Disassembly and inspection requires partial system draindown and significant maintenance and operations resources.

5) Attempts to utilize non-intrusive techniques have provided inconclusive results to date.

3.3.2 Ali nnative Testina The licensee proposes:

These check valves will be v9rified operable by disassembling and inspecting one valve from each sample group on a nominal refueling cycle frequency of 18 months (i 25%). This will not result in a reduction in the number of inspections that would have been performed over the life of the plant at the previous refueling cutage test frequency. This inspection will be conducted during an Essential Cooling Water A0T outage or refueling o ' a to ensure no degradation has occurred and to provide b ine data for any future nonintrusive check valve testing metri,as. By disassembling each valve during its associated A0T outage or refueling outage, all valves in both sample groups will be disassembled and inspected within-six years as required by GL 89-04, Fosition 2. If a generic failure occurs, a plan of action for inspection the remaining valves in the sample group will be developed utilizing the Condition Reporting Process and the guidance provided in GL 91-18. This plan of action will take into account the potential failure modes [ including common-mode failures) and their associated plant impacts and will be implemented in a time frame commensurate with their safety significance.

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3.3.3 Evaluation l The Code requires that these check valves be exercised to their safety '

position quarterly or during cold shutdowns. In order to test these valves in i accordance with the Code requirements, the ECW system must be partially i drained. Compliance with the Code test frequency requirements would result in

- a hardship on the licensee without a compensating increase in safety-since the ,

licensee propoi,es other means to provide assurance of valve operability. The i licensee gas proposed to perform sample disassembly and inspection of the ECW check valves during any mode of plant operation when the associated ECW train  !

is out of service at a time interval consistent with a refueling outage schedule. The proposed testing provides a reasonable assurance of operational readiness b6cause: .1) the_ disassembly method is being performed in accordance with the guidance in GL 89-04, Position 2; and 2) the test interval is consistent with the tast interval specified in Position 2. In addition, the proposed alternative testing minimizes the out-of-service time of safety-related equipment.

3.3.4 Conclusion The proposed alternative to the Code test frequency requirements for the ECW check valves EW-0370A, -03708 -0370C, and EW-403, -404, and -405 is 1 authorized pursuant to 10 CFP. 50.5fa(a)(3)Oi) based on the determination that compliance with the Code test frequency requirements results in a hardship without a compensating increase in the level of quality and safety.

4.0 CONCLUSig The NRC has determined that the licensee's request for relief is granted and

- proposals for alternatives are authorized in accordance with 10 CFR 50.55a, para raphs (f)('i)(1), for Relief Requests RR-34, Pev. 1, and RR-31 Rev. 1, or (a)( )(11) for pelief Requests RR-53, Rev.1, RR-49, Rev.1 RR-55, and RR-5 . In granting relief from the requirements of the ASME Code in accordance with paragraph (f)C6)(1), the NRC has determined that the requirements of the Code ara tapractical and relief is authorized by law and will not endanger life or property or the common defense and security and is .

otherwise in the public interest. Such relief has been granted giving due consideration to the burden on the licensee if the requirements were imposed on theLfacility. In authorizing alternatives from the requirements of the ASME Code in accordance with paragraph (a)(3)(11) .the NRC has determined that .

compliance with the Code will result in hardship or unusual difficulty without a compensating increase in the level of quality and safety, i Principal Contributors: P.-Campbell J. Colaccino T. Alexion

; Cate

November 17, 1997 ^

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