ML20128C918
| ML20128C918 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 01/22/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20127E334 | List: |
| References | |
| NUDOCS 9302040200 | |
| Download: ML20128C918 (8) | |
Text
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SAFETY EVALUATION BY THE OFFICE OF tutCLEAR REACTOR REGULATION RELATED TO THE INSERVICE TESTING PROGRAM RE0 VESTS FOR REllEF ENTERGY OPERATIONS. INC.
ARKANSAS NUCLEAR ONE. UNIT 2 DOCKET NUMBER 50-368
1.0 INTRODUCTION
Title 10 of the Coce of Federal Regulations,10 CFR 50 55a, requires that inservice testing (IST) of certain 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 and applicable addenda, except where alternatives are authorized or relief is granted by the Commission pursuant to 10 CFR 50,55a(a)(3)(i), (a)(3)(ii), or (f)(6)(i). In order to obtain authorization or 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.
The NRC guidance contained in Generic letter (GL) 89-04, " Guidance on Developing Acceptable Inservice Testing Programs " provided alternatives to the Code requirements determined to be acceptable to the staff.
Title 10 of the Code of Federal Regulations,10 CFR 50.55a, authorizes the Commission to approve alternatives or grant relief from ASME Code requirements upon making the necessary findings. The NRC staff's findings with respect to relief requested and alternatives proposed as part of the licensee's IST program are contained in this Safety Evaluation (SE).
The IST program addressed herein covers the second 10-year inspection interval from March 26, 1990, to March 25, 2000. Entergy Operations, Inc. (the licensee), submitted Revision 1 of the Arkansas Nuclear One, Unit 2 (ANO-2) second 10-year pump and valve IST program by letter dated August 9,1991.
Revision 1 superseded Revision 0 that was submitted on January 12, 1990. An additional submittal concerning the IST program was sent by letter dated February 13, 1992. The licensee's program is based on the requirements of Section XI of the ASME Code, 1986 Edition.
2.0 EVALUATION The licensee's requests for relief from the requirements of Section XI have been reviewed by the staff with the assistance of its contractor, EG&G Idaho, Inc. (EG&G). The Technical Evaluation Report (TER) provided as Attac'nment 2 is EG&G's evaluation of the licensee's IST program relief requests in the submittal dated August 9, 1991. The staff has reviewed the TER and concurs 9302040200 930122 PDR ADOCK 05000360 P PDR
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4 with the evaluations and conclusions contained therein except for a wording change: the term " relief granted" in the conclusions should be replaced by
" alternative authorized" for those requests approved pursuant to 10 CFR 50.55a(a)(3)(1) and (a)(3)(ii). This wording change also applies to Attachment 1 of this SE which presents a summary of the request determinations for the August 9, 1991, suomittal. In addition, the staff notes that the TER references an incorrect second 10-year inspection interval and references a July 31,1991, letter that is not relevant to this SE. Relief request PR-6, contained in the letter dated February 13, 1992, was evaluated separately by the staff and is addressed in Section 2.1 of this SE. The granting of relief or authorization of proposed alternatives is based upon the fulfillment of any commitments made by the licensee in its basis for each relief request and the alternatives proposed. The implementation of IST program is subject to inspection by NRC.
The licensee should refer to Appendix A of the TER and Section 2.1.2 of this SE for a discussion cf IST program anomalies identified during the review.
The licensee should resolve all anomalies in accordance with the guidance therein.
2.1 Relief Reauest PR-6 in submittal dated February 13. 1992 The licensee requested relief from the requirements of Section XI, Paragraph IWP-3100, for establishing differential pressure and flow rate reference conditions on the service water pumps 2P-4A, 4B, and 4C. The licensee proposed to use pump curves to compare differential pressure and flow rate during pump tests.
2.1.1 Licensee's Basis for Reouestina Relief The service water pumps 2P-4A, 4B, and 4C provide an assured source of cooling water to various safety-related and safe shutdown components. They also provide cooling water to various balance-of-plant components during normal plant operation.
During normal plant operation, either two or three service water pumps are required to be in operation. The pumps provide cooling water flow to the two safety grade service water loops and to the non-safety grade auxiliary cooling water loop. Interrupting the cooling water flow to these loops would result in a transient or a plant trip. The system flow requirements are defined by the service loads of the components in the system. Throttling of the pump discharge valve would cause a loss of adequate flow to heat exchangers and aligning additional loads to achieve a repeatable flow condition is not feasible because of system loading variations.
Multiple sets of reference values are used for monitoring pump hydraulic performance. The reference flow versus differential pressure curve represents hydraulic performance over the entire flow range of the pump. The reference curve is generated by varying system loading to span the range of flows encountered in normal operation and accident condition. Pump differential pressure is measured at each flow point, ar.d flow versus differential pressure Wg a.'i- _ , _ ~____--._____m-__.-..- - _ - - . - - - - - -
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reference curve is generated. Alert and required action range curves are derived as the multipliers of the reference value curve such that the appropriate acceptance criteria are specified at any point on the curve. The reference curve is reconfirmed or a new one defined by the collection of-several data points at various flows following significant maintenance activities involving rotating assembly removal, repair, or replacement. The~
reference curve is reconfirmed by performance of the normal inservice quarterly test following less significant maintenance activities.
The system load requirements define the flow at which a particular inservice test is run. The pump differential pressure is measured and compared to the reference curve and associtted acceptance criteria at that flow. The difference between the reference curve and the actual pump operating point is converted to a percent deviation value that is used for trending purposes'.-
The percent deviation is calculated by subtracting the reference curve value from the test value and then dividing by the reference curve value. ,
The pump vibration is monitored using a single reference value. In-plant testing has shown that the use of a curve, for monitoring this parameter because of varying flow conditions, is unwarranted. The test results indicate that the vibration levels are not flow dependent over the range of typical inservice test flows associated with these pumps.
2.1.2 Evaluation The' ASME Section XI, Subsection IWP requires that pump flow rate and differential pressure be evaluated against reference values to monitor pump condition and to allow detection of hydraulic degradation. When it is impractical to test a pump at a reference value of flow and differential pressure, testing in the "as-found" condition and comparing -values to an established reference curve may be an acceptable alternative. Pump curves represent a set of infinite reference points of flow rate and differential pressure. Establishing a reference curve for.a pump when it is known-to be operating acceptably, and basing the acceptance criteria on this curve, can permit evaluation of pump condition and detection of degradation, though not in accordance with Subsection IWP. There is, however, a higher degree of uncertainty associated with using a curve to assess operational readiness.
Therefore, the development of the reference curve should be as accurate as possible. Additionally, when using reference curves, it may be more difficult to identify instrument drift or to trend changes in component condition.
The service water pumps, 2P-4A, 4B, and 4C, operate under a variety of flow rate and differential pressure conditions. Varying the flow rate of these-pumps is impractical during normal plant operating conditions because of potential for loss of adequate flow to heat exchangers. Interruption of-cooling water flow could cause a reactor transient or a trip.
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The use of pump-curves can be an acceptable alternative to IWP-3100 requirements.' However, because of a greater potential for error associated with the use of pump curves, the following elements should be incorporated-into the inservice testing program and procedures for developing:and l implementing the curves: >
- 1) Curves are developed, or manufacture's pump curves are validated, when the pumps are known to be operating acceptably.
- 2) The reference points used to develop or validate the curve are. measured using instruments at least as accurate as required by the Code.
- 3) Curves are based on an adequate number of points, with a minimum of five.
- 4) Points are beyond the " flat" portion (low flow rates) of the curve in a range which includes or is as close as practicable to design basis flow-rates.
- 5) Acceptance criteria based on the curves do not conflict with Technical Specification or Facility Safety Analysis Report operability criteria, for flow rate and differential pressure, for the affected pumps.
- 6) If vibration levels vary significantly over the range of pump conditions, a method for assigning appropriate vibration acceptance criteria should-be developed for regions of the pump curve.
- 7) When the reference curve may have been affected by repair,. replacement, ,
or routine service, a new reference curve shall be determined or the previous curve revalidated by an inservice test.
With regard to converting test data for trending purposes, the proposed calculation for " percent" deviation appears as fraction of deviation, a value that is 100 times less. The saftty significance of this error in monitoring pump degradation should be determined; and appropriate corrective actions-should be taken.
Based on the determination that compliance with the Code requirements is^
impractical, and considering the burden on the licensee-if the Code'-
requirements are imposed, relief is granted from the' Code requirements pursuant to 10 CFR 50.55a(f)(6)(i) provided the seven elements and the correct definition of percent deviation, indicated above, are incorporated into the-
.IST program.
3.0 CONCLUSION
In evaluating the licensee's requests .for relief from the requirements of Section XI, the staff considered (1) the acceptability of proposed alternative testing,-(2) whether'the hardship of compliance is without a compensating increase in safety, and-(3) the impracticality of performing the required
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testing considering the burden if the requirements were imposed. Section 2.1.2 and the last column of Attacr...ent 1 identify the regulations under which the requests are approved. The staff has determined that granting relief pursuant to 10 CFR 50.55a(f)(6)(1) is authorized by law and will not endanger life or property, or the common defense and security and is otherwise in the public interest. The granting of relief or authorization of proposed alternatives is based upon the fulfillment of any commitments made by the licensee in its basis for each relief request and the proposed alternate testing.
Attachments:
- 1. Relief Request Summary
- 2. Technical Evaluation Report Principal Contributor: K. Dempsey Date: January 22, 1993
ATTACHMENT 1 Page No. 1 09/10/92
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ARKANSAS NUCLEAR ONE - UNIT 2 SAFETY EVALUATION TABLE 1
SUMMARY
OF RELIEF REQUESTS RELIEF TER SECTION XI EQUIPMENT ALTERNATE ACTION REQUEST SECTION REQUIREMENT IDENTIFICATION METHOD OF BY NUMBER & SUBJECT TESTING USNRC PR-1 2.1.1.1 IWP-4310: All pumps in the Measure pump Relief Granted Measure IST program, vibration velocities (a)(3)(1) bearing quarterly, temperatures.
PR 5 2.1.2.1 IWP-4500: All pumps in the Measure pump Provisional Relief Measure pump IST program. vibration velocities Granted vibration in accordance with (a)(3)(i) displacement. ASME OM-6.
PR 2 2.2.1.1 IWP-3100: Service water Verify bearing Relief Granted Observe pumps: condition by 2P4A, 2PAB, and quarterly flow (f)(6)(i) lubricant level or 2P4C testing and pressure, vibration velocity measurements.
PR 4 2.3.1.1 IWP-4120: Chargingpumps: Use installed flow Interim Relief Instrument 2P36A, cP36B, instruments that Granted full scale and 2P36C axceed the (a)(3)(ii),
range. full-scale range for one year or requirements. until the next refueling outage.
PR-3 2.4.1.1 IWP-4230: HPSI pumps: Use pressure Relief Granted Pump 2P89A, 2P89B, instruments that are (a)(3)(ii) differential and 2P89C not directly in the pressure test flow paths.
instrument-location.
GR-1 3.1.1.1 IWV-3300: Solenoid Verify remote Provisional Verify remote operated valves )osition indication Relief Granted position 3y monitoring system (f)(6)(i) indication, parameters.
GR-2 N/A IWV 3427 Containment Trend lea (b):isolation kage Do not trend rates, take leakage A[nproved G 89-04, per rates. valves. corrective actions Position 10, when leakage rate request not limits are exceeded, evaluated in SE/TER.
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Page No. 2 09/10/92 ARKANSAS NUCLEAR ONE - UNIT 2 '
SAFETY-EVALUATION TABLE 1
SUMMARY
_OF RELIEF REQUESTS RELIEF TER SECTION XI EQUIPMENT ALTERNATE ACTION REQUEST SECTION REQUIREMENT IDENTIFICATION METHOD OF BY NUMBER & SUBJECT TESTING USNRC GR-3 3.1.2.1 IVW-3417(b): All valves in Use the plant Provisional Valve the IST program, startup criteria of Relief Granted corrective the ANO Technicsl (a)(3)(1) action Specifications.
requirements.
GR-4 N/A IWV-3417(a): Rapid-acting Assign a limit of 2 A) proved per Compare valves seconds to G. 89-04, stroke time rapid-acting valves. Position 6, with previous request not measurement, evaluated in SE/TER.
EFW-1 N/A IWV 3521: Service water Verify full-stroke A)
Exercising supply to capability by sample G. proved 89-04, per method and emergency disassembly during Position 2, frequency. feedwater check refueling outages. request not valves: evaluated in SE/TER.
2EFW-2A and 2EFW 2B SGS-1 3.2.1.1 IWV-3521: Steam supply Verify valve closure Provisional Exercising check valves to capability by sample Relief Granted method and frequency.
the EFW turbine: disassembly during 2MS-39A and refueling outages.
(f)(6)(i) 2MS-39B SU l N/A IWV-3521: Service water Verify full-stroke A)
Exercising return from capability by sample G. proved 89-04, per method and shutdown cooling disassembly during Position 2,-
frequency. HXs: refueling outages. -request not 25W-12A and evaluated in SE/TER, 2SW-128 RC-1 3.3.1.1 IWV-3521: HPSI to RCS hot Full-stroke exercise Relief Granted Part 1 Exercising leg injection the valves open (f)(6)(i) frequency. check valves: during refueling-2SI-27A, outages.
251-27B, 2SI-28A, and 2S1-28B l
b 47 +
Pa e No. _3 109 10/92; - .
.' ARKANSAS NUCLEAR ONE UNIT 2! .
SAFETY' EVALUATION TABLE 1-
SUMMARY
OF_ RELIEF REQUESTS-RELIEF TER SECTION XI EQUIPMENT- ? ALTERNATE- ACTION REQUEST SECTION . . REQUIREMENT IDENTIFICATION- METHOD OF. - BY ~ .
NUMBER & SUBJECT ' 1 TESTING _- ..USNRC-RC-1 3.3.1.I' IWV-3422: HPSI to RCS hot Monitor the upstream Interim Rell'ef'.
Part 2 Individual leg injection side of these valves Granted-leak rate check valves: . once every 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> - (f)(6)(1) -
testing. 2SI 27A . to verify their-leak for one--year-or, 251 27B, tight integrity. Juntil -the next 2SI-28A,_and refueling. outage.<-
2SI 28B SI I 3.4.1.1 IWV-3521: HPSI pump -Full-stroke exercise Relief Granted Exercising- suction, valves with flow . (f)(6)(i) frequency, dischar , and during refueling .
injecti header outages check valves listed in the program.
a 2 N/A IWV 3521: Safety injection Verify full stroke : Approved per- l Exercising tank cutlet and- capabilit by sample GL-89 04,.
method-and combined safety disassemb y during- Position 2 .
frequency. in ection-header-refueling outages. - requestJnot-ch ck valves: evaluated in SE/TER. ' '
2SI-15A thru-D-and 2SI-16A-thru-
.*D CS-1 N/A IWV 3521: Refueling water -Verif full-stroke A) proved per L Exercising: tank outlet capab lit b sample G. 89-04,
- method anc' check valves: disassembyguring LPosition-2, a frequency. 2BS-1A and refueling outages, request not- ,
285-18: = evaluated in SE/TER.
CS-2 N/A IWV-3521: ' Containment 'Ai Exercising s) ray header Verify full-stroke'by sample capabilit 89 04, G. proved per-method and c1eck-valves: disassemb y during : Position 2, frequency. '2BS-5A andi refueling outages. : request not'-
2B5-5B evaluated in SE/TER;.
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