ML19256F371
| ML19256F371 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 11/16/1979 |
| From: | Seyfrit K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Millen C PUBLIC SERVICE CO. OF COLORADO |
| References | |
| NUDOCS 7912190030 | |
| Download: ML19256F371 (1) | |
Text
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UNITED STATES IIC f'pa mou,'g, s
NUCLEAR REGULATORY COMMISSION
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/o REGloN IV 21 I
0 G11 RY AN PLAZ A DRIVE, SutTE 1000 qk l. f ARLINGTON, TEXAS 7G012
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November 16, 1979
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Docket No. 50-267 Public Service Company of Colorado ATTN:
Pr. C. K. Millen Senior Vice President P. O. Bo:. 840 Denver, Colorado 80201 Gentlemen:
The enclosed IE Circular No. 79-22, is foruarded to you for inforcation.
No written response is required. Should you have any questions related to your understanding of this matter, please contact this office.
Sincerely,
((/
C Karl V. 5 frit Director i
Enclosures:
1.
IE Circular No. 79-22 2.
Recently Issued IE Circulars cc:
D. W. Waresbourg, Nuclear Production Manager Fort St. Vrain Nuclear Station P. O. Box 368 Platteville, Colorado 80651 L. Brey, Manager, Quality Assurance 1625 049 7912190 030
SSINS:
6830 Accession No.:
7908220142 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D. C.
20555 IE Circular No. 79-22 Date: 1;ovember 16, 1979 Page 1 of 1 STROKE TIMES FOR POWER OPERATED RELIEF 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 February 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 050
IE Circular No. 79-22 November 16, 1979 RECENTLY ISSUED IE CIRCULARS Circular Subject Date Issued To No.
Issued 79-14 Unaut'orized Procurement 7/13/79 All Medical Licensees u
and Distribution of Except Teletheraphy XE-133 Hedical 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 Safety-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 Operating Licenses (OLs) or Construction Permits (cps)
Enclosure 1625 051