ML20203E852

SER Accepting Request for Relief from Requirements of 10CFR50.55a(f) for Performing Required Inservice Testing of Certain Class 2 Components IAW ASME Boiler & Pressure Vessel Code Section XI for Plant,Unit 3

ML20203E852
Person / Time
Site:	Millstone
Issue date:	02/17/1998
From:	NRC (Affiliation Not Assigned)
To:
Shared Package
ML20203E831	List: ML20203E825 ML20203E852
References
NUDOCS 9802270146
Download: ML20203E852 (3)

Text

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8(# ~ UNITED STATES

{ t NUCLf1AR REQULATORY COMMISSION wASHINeToN, D.C. asseHoot BAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO A REQUEST FOR RELIEF FROM ASME_ CODE SECTION XI REQUIREMENTS NORTHEAST MUCL EAR ENERGY COMPANY. ET AL, MILLSTONE NUCLEAR POWER STATION UNIT No. 3 QQCKET No. 50-423

1.0 INTRODUCTION

The Technical Specifications for Millstone Unit 3, state that the inservice inspection and testing of the American Society of Mechanical Engineers (ASME) Code Class 1,2, and 3 components shall be performed in accordance with Sectl0n XI of the ASME Boller and Pressure Vessel Cede (ASME Code) and applicable Addenda as required by Title 10 of the Code of Federal Raoulations -

(10 CFR), Part 50, Section 50.55a. Section 50.55a(a)(3) states that attematives to te*

requirements of paragraph (f) may be used, when avthorized by the NRC, if (i) the propsed attematives would provide an acceptable level of quality and safety, sr (ii) cc ,liance with the specified requirements would result in hardship or unusual difficuP.y without e compensating

, increase in the level of quality and safety, The first 10 year inservice testing (IST) interval for Millstone Unit 3 began on April 24,1986, and was scheduled to end on April 23,1996. Because Millstone Unit 3 is currently in an extended outage, the ASME Code allows extensions of the 10 year interval. The licensee has documented its start date in a letter dated October 25,1997, as ' prior to entry into Mode 4." The second 10 year intervallST program for Millstone Unit 3 will be based on the requirements of the 1989 Edition of ASME Section XI that references the OMe.1988, Part 6 for pumps and Part 10 for valves, Northeast Nuclear Energy Company (NNECO/the licensee) submitted Relief Request PR 1 in a for Millstone Unit 3.Approval Requested to Support Mode 4 Operations Scheduled for Jan 1998|letter dated January 8,1998]], and proposed a one time altomative to the Code requirements which specifies that prior to the establishment of new pump reference values, an inservice test shall be run at the conditic,s of an existing set of reference values. The staff's evah'ation of Relief Request PR 1 is included in Section 3.0 of this safety evaluation (SE),

2.0 DISCUSSION Component identification

. Recirculation Spray System pumps 3RSS*P1 A, P1B,- Pic, P1D--

' Code Class 2-9002270146 990217 PDR ADOCK 05000423 I Enclosure

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2 Code Requiremat OM 6, paragraph 4.5, "To establish an additional set of reference values?

Licensee's Code Rollef Request The licensee requested the following:

[P)ursuant to 10 CFR 50.55a(f)(5)(lii), NNECO hereby requests one time relief from the IST requiremen' of the OM S code (paragraph 4.5). This requires that a pump test be performed at ti existing reference values pnor to system modifications when establishing an udditional set of reference values for future evaluation of pump performance and determination of pump operability, Licensee's Basis for Requesting Relief The licensee provided the following basis for the relief request:

The Recirculation Spray system [RSS) was modined during the extended shutdown which began in May 1996. Due to changes in the design basis of the RSS system, orifice plates were installed in t.w pump discharge piping for *rch line to reduce maximum flow capacity. Dunng the initial design enange review, a pump test at the existing reference -

values, prior to system modifications, was not identified as a requirement of the OM 6 code. Concurrent to the modification, it has been determined that a t# fun at the .

previous reference values should be performed whenever reference ym,cs art .'1anJed, however the arrent system modification limits flow to less than the previous reference flow (flow limited to approximately 3000 gpm [ gallons per minute) and previous reference flow was 4150 gpm).

To allow testing at the previous reference values, system hardware changes, installed during the current outage, would have to be dismantled, This would involve removing the orifice plates, manufacture and installation of dum tly plates, and re Installing the original orifice plates after testing was complete. Implementing these changes just to run a test at the previous reference values will not provide any additional value to the determination of pump operability than the scheduled post modification testing. The post modification testing is a more comprehensive test which will compare each pump's performance against the original pump performance curves (testing at 5 points up to approximately 3000 gpm). This post modification test, as an attemative to the code test, would allow clear determination of the pumps operating status and provida an acceptable level of quality and safety with regard to RSS pump testing.

The preposed attemative testing will verify the original pump curve, up to approximately 3000 gpm, as compared to a one point verification as required by ne code. This testing provides sufficient verification of each pump's operating stasus such that new reference

- values can be established from which deviations in pump performance, relative to original performance, can be readily detected. An evaluation of past RSS pump test results has identified that there are no signs of performance degradation and all four pumps continue to run as new, consistent with low cumulative run times, i.e. less than 200 hours0.00231 days <br />0.0556 hours <br />3.306878e-4 weeks <br />7.61e-5 months <br />. The pumps have been idle for approximately 22 months during the current extended shutdown and thus should not have experienced any degradation.

e 3-Licensee's Proposed Alternative Examination The licensee proposed the following:

All four RSS pumps will be tested at flowrotes of approximately 3000,2500,2000,1500 and 1000 gpm as part of the post modification testing to support determ'.iation of pump operability. Pump performance at each test point will be compared to the original factory performance curve, the RSS system design criteria and pump manufacturer acceptance criteria. Any discrepancies in pump performance will be dispositioned in accordance with ASME OM-6 corrective actions. Additionally each pump will be tested it the minimum recirculation flow to establish new reference values.

3.0 EVALUATION The four RSS pumps have a safety function to provide flow to the recirculation spray headers during the injection phase of the accident and provide long term cooling during the recirculation .

phase of the accident. The previous inservice test for these pumps was performed at a reference flow rate of 4150 gpm. During the current extended outage, the RSS system was modified to reduce the maximum flow rate to approximately 3000 gpm by installing orifice plates on the discharge of each pump.

The Code requires for safety related pumps that prior to establishing an additional set of reference values, an inservice test shall first be run at the conditions of an existing set of reference values and the results analyzed. To meet the Code requirements, the licensee would be required to remove the installed orifice plates for each pump, perform the Code required test to reconfirm the previous reference values, and reinstrll the plates. This would result in a hardship for the licensee without a compensating increase in safety if there are other means to demonstrate acceptable pump operation.

The licensee has proposed to perform a post modification test which consists of collecting performance data for each pump at five points and then comparing this data to the original factory performance curve, the RSS system design criteria, ano the pump manufacturer acceptance criteri3. In addition, the ASME corrective action requirements will be adhered to in this post modifie.ation test. The NRC staff has concluded that the proposed testing provides seasonable assurance of operational readiness because the attemative test of taking five data points across virtually the entire range of pump operation (500 gpm to 3000 gpm) is more stringent than the Code-required test.

4.0 CONCLUSION

The staff conclude that pursuant to 10 CFR 50.55a(a)(3)(ii), the proposed attemative described in the enclosed SE may be authorized in that compliancc with the specif,ed requirements of this section would result in hardship or unusual difficulty without a compensating increase in the level of quality and safety.

Principle Contributors: Jim Andersen Joseph Colaccino Date: February 17, 1998

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