ML20057E347
| ML20057E347 | |
| Person / Time | |
|---|---|
| Site: | Fort Calhoun  |
| Issue date: | 10/01/1993 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20057E346 | List: |
| References | |
| NUDOCS 9310120049 | |
| Download: ML20057E347 (4) | |
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E NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20565-0001
%.....,o SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO THE INSERVICE TESTING PROGRAM RELIEF RE00EST E4 OMAHA PUBLIC POWER DISTRICT FORT CALHOUN STATION. UNIT I DOCKET NO. 50-285
1.0 INTRODUCTION
Section 50.55a of Title 10 of the Code of Federal Regulations requires that inservice testing (IST) of certain American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code) Class 1, 2, and 3 pumps and valves be performed in accordance with Section XI of the ASME 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 i
(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 i
difficulty without a compensating increase in the level of quality and safety, I
or (3) conformance is impractical for its facility.
NRC guidance contained in Generic Letter (GL) 89-04, " Guidance on Developing Acceptable Inservice Testing Programs," provided acceptable alternatives to the Code requirements.
4 When an alternative is proposed that is in accordance with GL 89-04 guidance and that is documented in the IST program, no further evaluation is required; however, implementation of the alternative is subject to NRC inspection.
furthermore, in rulemaking to 10 CFR 50.55a, effective September 8,1992 (see 57 FR 34666), the 1989 edition of ASME Section XI was incorporated in 10 CFR 50.55a(b). The 1989 edition provides that the rules for IST of pumps and valves shall meet the requirements set forth in ASME Operations and Maintenance Standards Part 6 (OM-6), " Inservice Testing of Pumps in Light-Water Reactor Power Plants," and Part 10 (OM-10), " Inservice Testing of Valves in Light-Water Reactor Power Plants." Pursuant to 10 CFR 50.55a(f)(4)(iv),
portions of editions or addenda may be used provided that all related requirements of the respective editions or addenda are met; therefore, relief is not required for those inservice tests that are conducted in accordance with OM-6 and OM-10, or portions thereof. Whether all related requirements are met is subject to NRC inspection, i
Section 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).
9310120049 931001 PDR ADOCK 05000285 P
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' This SE concerns relief request E4 for the Fort Calhoun Station (FCS) third 10-year pump and valve IST program.
Relief request E4 was submitted by Omaha Public Power District (the licensee) in a letter dated November 13, 1992.
This IST program is based on the requirements of Section XI of the ASME Code, 1989 Edition. Relief request E4 is an updated version of relief request E19 submitted for the second 10-year interval ending September 25, 1993. The NRC SE dated March 26, 1992, granted relief for E19 on an interim basis pending completion of staff's detailed evaluation of the licensee's valve exercising methodology. The evaluation in Section 3.0 below for relief request E4 completes this detailed evaluation and the review of E19. The SE for other relief requests submitted for the third 10-year interval, which begins on September 26, 1993, will be provided at a later date.
2.0 RELIEF RE0 VEST E-4 The licensee requested relief from exercising safety injection tank (SIT) check valves SI-207, SI-208, SI-211, SI-212, SI-215, SI-216,51-219, and SI-220, in accordance with the requirements of OM-10, Paragraph 4.3.2.2.
2.1 Licensee *s Basis for Reauestina Relief The licensee provided the following basis:
"These valves cannot be exercised during power operation because a flow path does not exist due to higher RCS
[ reactor coolant system] pressure.
The safety injection tank pressure is less than RCS pressure during power operation. Also, these check valves cannot be exercised during cold shutdowns because the RCS does not contain sufficient volume to accept the flow required and a low temperature overpressure condition of the RCS could result."
2.2 Alternative testina The licensee proposed the following alternative in the relief request:
" Check valves will be full-stroked in the open direction during refueling outages by
' dumping' the safety injection [SI] tanks to the reactor vessel.
Test parameters such as SI tank level decrease vs. time, SI tank pressure, valve differential pressure, flow rate, etc., are used to determine a flow coefficient.
The minimum flow coefficient was determined using the safety analysis data provided by the NSSS [ nuclear steam supply system] vendor.
Comparing this minimum flow coefficient as acceptable criteria to the flow coefficient determined by testing, assures FCS the valve is able to perform its safety function. This method of testing the check valves complies with the guidance provided in Generic Letter 89-04, Attachment 1, Position 1.
Additionally, valves SI-208, SI-212, SI-216, and SI-220 will be partial-stroked exercised at cold shutdown frequency in the open direction using shutdown cooling flow."
Table 2.1, " Fort Calhoun Valve Test Program Matrix," indicates that the valves in this relief request are also verified to close by leak testing as pressure
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' isolation valves (PIVs) per plant technical specifications. The PIV leak testing frequency specified in the IST program is as follows:
(1) prior to entering the power operation mode every time the plant is placed in the cold shutdown condition for refueling; (2) each time the plant is placed in a cold shutdown condition for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> if testing has not been accomplished in the preceding 9 months; and (3) prior to returning the valve to service after maintenance, repair, or replacement work is performed.
3.0 EVALUATION Full-stroke exercising these valves during power operation is not practicable because the RCS is at a higher pressure than the SIT. During cold shutdowns, the RCS lacks adequate expansion volume to accommodate the required flow; a low-temperature overpressure condition could result. These valves could only be full-stroked exercised quarterly or during cold shutdowns if extensive system modification were performed, such as installation of full-flow test loops. Making such modifications would be burdensome to the licensee.
Since the licensee is full-stroke exercising shutdown cooling injection check valves SI-194, -197, -200, and -203 during cold shutdowns, valves SI-208, -212, -216, and -220 can be partial-stroke exercised at the same frequency because they are located in the same flow path.
The licensee proposed to full-stroke open these valves during refueling outages and partial-stroke open valves SI-208, -212, -216, and -220 during cold shutdowns.
Further, Table 2.1, " Fort Calhoun Valve Test Program Matrix,"
indicates that the valves are also verified to close by leak testing per plant technical specifications for PIVs. The frequency of PIV leak testing is specified above in Section 2.2.
The alternative testing frequencies are i
consistent with the requirements of OM-10, Paragraph 4.3.2.2, which allows deferral of stroke testing to every refueling outage if testing quarterly or j
during cold shutdowns are not practicable. However, the licensee should document the justification for deferral of stroke testing in accordance with OM-10, Paragraph 6.2(d).
Since the method of exercising these valves open depends upon combination of test and analyses, the staff with the assistance of its contractor, Oak Ridge National Laboratory (ORNL), undertook a detailed evaluation of the licensee's methodology. The report, ORNL/NRC/LTR-93/16, " Analysis of Proposed Testing of Safety Injection Tank Discharge Check Valves Using a Flow Resistance Hethodology" (Enclosure 2), is ORNL's analysis of this methodology. The staff has reviewed this report and concurs with the evaluations and conclusions contained therein.
The licensee's method of exercising these valves open is consistent with the OM-10, Paragraph 4.3.2.2 requirements provided the recommendations regarding the use of higher accuracy test instrumentation, the readability of strip charts, the maximization of time increment available for
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i r l analysis, the effects of variation in the friction factor with the flow rate, and consideration of the use of non-intrusive monitoring, as specified in the ORNL report, are followed.
4.0 CONCLUSION
Based on the determination that the alternative testing is consistent with 0M-10, Paragraph 4.3.2.2 requirements, no relief is required provided the licensee documents the justification for deferral of stroke testing in accordance with OM-10, Paragraph 6.2(d), and follows the recommendations specified in ORNL/NRC/LTR-93/16.
If the licensee cannot meet these provisions, a revised relief request should be submitted within 90 days of the date of this SE.
The implementation of IST program commitments is subject to NRC inspection.
Principal Contributor:
K. Dempsey Date: October 1, 1993 l
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