ML20076D002
| ML20076D002 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 07/15/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20076D000 | List: |
| References | |
| NUDOCS 9107250230 | |
| Download: ML20076D002 (3) | |
Text
.____- ____-____ _ _ ___
[j
- 'og p
0, UNITED STATES 3,
j.
I NUCLEAR REGULATORY COMMISSION o,
WASHINGTON. D C. 20u6
%.'.... /
{
i SAFETY EVALVATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NOS. 147 AND 131 TO FACILITY OPERATING LICENSE NOS. NPF.4 AND NPF-7
[
VIRGINIA ELECTRIC AND POWER COMPANY OLD DOMINION ELECTRIC COOPERATIVE NORTH ANilA POWER STATION, UNITS NO. 1-AND NO.-2 DOCKET NOS. 50-338 AND 50-339
1.0 INTRODUCTION
ByletterdatedDecember28[thelicensee)requestedachangetotheTechnical 1989, as modified February 14, 1991, the Virginia Electric and Power Company 1
Specifications (TS)fortheNorthAnnaPowerStation,UnitsNo.IandNo.2 (NA-182). The change would revise the acceptance criteria for the monthly testing of auxiliary feedwater (AFW) pumps required by the NA-182 TS 4.7.1.2.a.
4 Specifically, the change would delete the current specific discharge p(motor-ressure l
and flow values of at least 1250 psig at 53 gallons per minute (gpm) driven pumps) and 1380 psig at 35 gpm (turbine-driven pump). The change would allow acceptance discharge pressure and flow rates to be established and periodir. ally reevaluated through ASitE Section XI testing.
2.0 DISCUSSION The AFW system is used to cool the steam generators, and therefore the reactor, when normal feedwater is lost or after a reactor trip. The AFW system includes two motor-driven pumps and one turbine-driven pump. TS 3.7.1.2 requires all three pumps to be OPERABLE in modes 1, 2 or 3 and TS 4.7.1.2 requires monthly testing on minimum flow recirculation.
~
The pumps were originally equipped with minimum flow recirculation lines dich include orifices just large enough to ensure that the pumps will not overheat when run with all.other flow paths closed. This mimimum flow was the basis tor the specific values of discharge pressure and flow rates specified in the NA-182 TS 4.7.1.2.a.
The pumps were not designed to run on recirculation for periods of time as currently required by the NA-182 TS, and during the recirculation mode of operation, the recirculation line orifices restrict flow to'less than 20% of best efficiency point flow and discharge pressure is
-near the pumps' shut-off head.
9 NRC Bu11etin-88-04, " Safety Related Pump Loss," identified concerns with instability of pumps operating near their shut-off heads.
In response to the i
Bulletin, the licensee committed to disassembling and inspecting the AFW pumps and to minimize operation at low flow. The initial inspections 4
L 9107250230 910715 FDR ADOCK 0500033s P
pyy i_,__-.___..~
o
t at NA-l&2 revealed problems on all six pumps, including diffuser vane cracks, scored bearings and tolerances out of specification.
A root-cause evaluation attributed part of these problems to testing in the recirculation mode at the currently specified TS discharge pressure and flow rates. All six pumps were overhauled and new full-flow recirculation lines were added to all six AfW pumps during the latest NA-l&2 refueling outages to allow full-flow testing at power without affecting the steam generators or normal feedwater regulation.
New benchmark perfortrance data was gathered for A$ tie Section XI testing by pumping at full flow to the steam generators and quarterly Section XI testing is now done at flow conditions near the AFW pumps' best efficiency.
Therefore, based on the above, the licensee's proposed change would delete the specific discharge pressure and flow rates specified in the current NA-l&2 TS 4.7.1.2.a and allow the monthly test to be conducted under ASliE Section XI criteria.
3.0 EVALUATION In response to NRC Dulletin 88-04, the licensee has implemented a detign change which will allow testing of the AFW pumps at power and full-flow conditions.
Pump testing under these parameters is similar to conditions under which the pumps would be performing their intended safety function.
Monthly testing conducted under the criteria of the licensee's quarterly ASt4E Section XI testing would allow the pumps to be tested at flow conditions near the AFW pumps' best efficiency point and thereby reduce pump wear,
- Finally, pump testing enveloped by ASME Section XI criteria would provide more meaningful data for pump performance assessment and periodic reevaluation, as well as increase long-term pump reliability.
Based on the above, the staff finds the proposed change to be acceptable.
4.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Virginia State official was notified of the proposed issuance of the amendments. The State official had no comment.
5.0 ENVIRONMENTAL CONSIDERATION
These amendments change a requirement with respect to installation or use of a facility component located within the restricted area 55 defined in 10 CFR Part 20.
The NRC staff has determined that the amendments involve no significant increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation exposure.
The Comission has previously issued a proposed finding that the amendments involve no significant hazards consideration and there has been no public coninent on such finding (56 FR 27050). Accordingly, these amendments meet the eligibility criteria 51.22(b)gorical exclusion set forth in 10 CFR 51.22(c)(9).
for cate pursuant to 10 CFR no environmental impact statement or environmental assessment need be prepared in connection with the issuance of these amendments, m
s 3
I
6.0 CONCLUSION
The Conunis ion has concluded, based on the considerations discussed above, that:
(1) there is reasonable assurance that the health and safety of the public will rot be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the conrnon defense and security or to the health and safety of the public.
Principal Contributor:
Leon Engle Date: July 15.1991 i
_