ML19256F368
| ML19256F368 | |
| Person / Time | |
|---|---|
| Site: | Cooper  |
| Issue date: | 11/16/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Pilant J NEBRASKA PUBLIC POWER DISTRICT |
| References | |
| NUDOCS 7912190026 | |
| Download: ML19256F368 (1) | |
Text
CENTRAL FILES PDR:HQ LPDR UNITED STATES
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NUCLEAR REGULATORY COMMISSION NSIC HEGloN IV O\\
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611 RY AN PL AZA D RIVE, SUITE 1000 5 /. 6 ARLINGTON, TEXAS 7G012 59' o.v-N'* -.414 $
Noveraber 16, 1979 Docket No.
50-253 Nebraska Public Power District ATTN:
J. M. Pilant, Director Licensing & Quality Assurance Post Of fice Box l+99 Columbus, Nebraska 68601 Gentlenea:
The enclosed IE Circular No. 79-22, is forwarded to you for information.
No written response is required.
Should you have any questions related to your understanding of this matter, please contact this office.
Sincerely, f-L o Karl V.
eyfrit Director
Enclosures:
1.
IE Circular No. 79-22 2.
Recently Issued IE Circulars cc:
L. C. Lessor, Superintendent Cooper Nuclear Station Post Of fice Box 98 Brownville, Nebraska 68321 1625 041 7 012190C2 ci
SSINS:
6830 Accession N>.:
7908220142 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D. C.
20555 IE Circular No. 79-22 Date: November 16, 1979 Page 1 of 1 STR0iG TIMES FOR POWER OPERATED RELIZF VALVES Description of Circumstances:
Most PWRs utilize power-operated relief valves (PORVs) to prevent overpressuriza-tion of the reactor coolant system when the reactor is at low temperature. On April 13, 1979, during a pressure transient at Robinson 2, the PORVs did not function as rapidly as intended.
The estimated stroke time for the PORVs was three to five seconds whereas the intended stroke time is two seconds.
As a result, the pressure transient did approach a pressure limit which is based on nil ductility considerations.
Prior to April 13, the PORVs had not been used'or exercised since Februacy 1978, when they had been repacked and stroked. Although the valve stems were scored at that time, stroke times were satisfactory.
The licensee and the valve manufacturer believe that the scored stems and the 14-month interval without exercise resulted in poor performance of the PORVs.
Recommended Actions for Licensees' Consideration:
All holders of PWR operating licenses or construction permits should be aware of the potential problem of the type discussed above.
Because of the generic implications in this matter, it is recommended that both licensees of operating facilities and holders of construction permits conduct a review to determine if periodic surveillance of PORVs is necessary to assure that the PORVs will perform as intended.
No written response to this Circular is required.
If you require additional information regarding these matters, contact the Director of the appropriate NRC Regional Office.
1625 042
IE Circular No. 79-22 November 16, 1979 RECENTLY ISSUED IE CIRCULARS Circular Subject Date Issued To No.
Issued 79-14 Unauthorized Procurement 7/13/79 All Medical Licensees and Distribution of Except Teletheraphy XE-133 Medical Licensees and to all Radiopharmaceutical Suppliers 79-15 Bursting of High Pressure 8/8/79 All Materials Priority I, Hose and Malfunction of Fuel Cycle and Operating Relief Valve "0" Ring in Power Reactor Licensees Certain Self-contained Breathing Apparatus 79-16 Excessive Radiation 8/16/79 All Radiography Exposures to Members Licensees of the General Public and a Radiographer 79-17 Contact Problem in SB-12 8/14/79 All Power Reactor Switches on General Licensees with a Electric Company Construction Permit Metalclad Circuit (CP) and/or Operating Breakers License (OL) 79-18 Proper Installation of 9/10/79 All Holders of a Target Rock Safetf-Relief Power Reactor Operating Valves License (OL) or Construction Permit (CP) 79-19 Loose Locking Devices on 9/13/79 All Power Reactor Ingersoll-Rand Pumps Licensees with a Construction Permit (CP) and/or Operating Licensee (OL) 79-20 Failure Of GTE Sylvania 9/24/79 All Power Reactor Relay, Type PM Bulletin Licensees with a 7305, Catalog SU12-11-AC Construction Permit (CP)
With A 120V AC Coil and/or Operating Licensee (OL) 79-21 Prevention of Unplanned 10/19/79 All holders of Power Releases of Radioactivity Reactor Orerating Licenses (OLs) or Construction Permits (cps)
Enclosure 1625 043