ML20213C765
| ML20213C765 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 11/04/1986 |
| From: | Larson C NORTHERN STATES POWER CO. |
| To: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| References | |
| IEB-85-003, IEB-85-3, NUDOCS 8611100260 | |
| Download: ML20213C765 (3) | |
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Northern States Power Company 414 Nicollet Matt Minneapohs. Minnesota 55401 Teephone (612) 330-5500 November 4, 1986 Mr. James G.
Keppler Regional Administrator - Region III U.
S.
Nuclear Regulatory Commission 799 Roosevelt Road Glen Ellyn, IL 60137 PRAIRIE ISLAND NUCLEAR GENERATING PLANT Docket Nos. 50-282 License Nos. DPR-42 50-306 DPR-60 Additional Response to IE Bulletin 85-03 In responses to IE Bulletin 85-03 dated July 4 and September 12, 1986, we committed to certain actions regarding motor-operated valves.
This response amends those responses in order to maintain long term operability of the identified motor valves without a burdensome amount of differential pressure testing.
In our original response, we committed to perform full differential pressure tests on all but four valves.
Subsequent evaluation has shown that differential pressure testing without determining actual stem thrust leaves no margin for maintenance, such as tightening valve packing, without further differential pressure testing.
As an alternative to full differential pressure testing, we will perform limited differential pressure testing and implement a program similar to that proposed by Motor Operated Valve Analysis and Test System, Inc. (MOVATS), and described in a briefing to the NRC in Bethesda on September 4,
1986 (the Blue Book approach).
The differential pressure tests performed will be " proof of principle" tests for valves that do not conform to already tested configurations at other utilities.
Each valve at Prairie Island will have a tested prototype or will have been tested itself.
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Mr James G Keppler November 4, 1986 Page 2 Correct settings for torque switches are derived using a hybrid of Limitorque and MOVATS methodologies.
Maximum settings are obtained from Limitorque, whereas actual settings are determined by using the more conservative stem thrust calculations, be it Limitorque or MOVATS.
Torque switches are then bypassed till approximately one second after the normal running load / current is reached.
The "as left" torque switch settings will be verified by measuring actual valve stem thrust during the torque switch calibrating procedures which will demonstrate that this thrust value exceeds the minimum calculated thrust required under full differential pressure conditions.
Motor signatures are also taken during any full differential pressure valve testing'to verify the calculations and methodology.
Furthermore, each of the IE Bulletin 85-03 identified motor valves will be MOVATS tested to verify the calculations and methodology to ensure full operability.
- m C E Larson Vice President, Nuclear Generation c:
NRR Project Manager, NRC Resident. Inspector, NRC
< Document. Control. Desk, NRC G Charnoff
o UNITED STATES NUCLEAR REGULATORY COMMISSION NORTHERN STATES POWER COMPANY PRAIRIE ISLAND NUCLEAR GENERATING PLANT Docket No. 50-282 50-306 ADDITIONAL RESPONSE TO IE BULLETIN 85-03 Northern States Power Company, a Minnesota corporation, by this letter dated November 4, 1986 hereby submits an additional response to IE Bulletin 85-03,
" Motor-Operated Valve Common Mode Failures During Plant Transients Due to Improper Switch Settings", for the Prairie Island Nuclear Generating Plant.
This letter contains no restricted or other defense information.
NORTHERN STATES POWER COMPANY By
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Vice Pre (s h, Nuclear Generation C E Lars n j
M day of Ibz[ev
//f6 _before me a notary public in and On this for said Coun'ty, personally appeared C E Larson, Vice President, Nuclear Generation, and being first duly sworn acknowledged that he is authorized to execute this document on behalf of Northern States Power Company, that he knows the contents thereof and that to the best of his knowledge, information and belief, the state-ments made in it are true and that it is not interposed for delay.
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! sg DODY A. BFIOSE i :
t40TARY PUBUC = MINNESOTA l HENNEPIN COUNTY i My Commission Empires Dec. 06.1989 ;
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