ML17053B243
| ML17053B243 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 11/16/1979 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Rhode G NIAGARA MOHAWK POWER CORP. |
| References | |
| NUDOCS 7912050044 | |
| Download: ML17053B243 (6) | |
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Docket No. 50-410 UNITED STATES NUCLEAR REGULATORY COMMISSION REGION I 631 PARK AVENUE KING OF PRUSSIA, PENNSYLVANIA19406 NOV I 6
)97'iagara Mohawk Power Corporation ATTN:
Mr.
G.
K.
Rhode Vice President System Project Management 300 Erie Boulevard, West
- Syracuse, New York 13202 Gentlemen:
The enclosed IE Circular No. 79-22, "Stroke Times for Power Operated Relief Valves," 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, Boyce H. Grier Director
Enclosures:
l.
IE Circular No. 79-22 2.
List of Recently Issued Circulars CONTACT:
D.
L. Caphton (215"337"5263) cc w/encls:
Eugene B. Thomas, Jr.,
Esquire
ENCLOSURE 1 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:
November 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, 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'onsideration:
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 faci,lities and holders of construction permits conduct a review to determine if periodic serveillance 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.
0 ENCLOSURE 2 Circular No.
Subject RECENTLY ISSUED CIRCULARS First Date of Issue IE Circular No. 79-22 Date:
November 16,'979 Page 1 of 1 Issued To 79-15 79-16 Bursting of High Pres-sure Hose and Malfunc-tion of Relief Valve "0" Ring in Certain Self-Contained Breathing Apparatus Excessive Radiation Exposures to Members Of The General Public And A Radiographer 8/8/79 8/16/79 All Materials Priority I, Fuel Cycle and Opera-ting Power Reactor Licensees All Radiography Licensees 79-17 Contact Problem in SB-12 Switches on General Electric Metalclad Circui.t Breakers 8/14/79 All Power Reactor Licensees with an OL or CP 79-18 79-19 79-20 79-21 Proper Installation of 9/10/79 Target Rock Safety-Relief Valves Loose Locking Devices 9/13/79 on Ingersoll-Rand Pumps Failure of GTE Sylvania 9/24/79
- Relay, Type PM Bulletin
- 7305, Catalog 5U12-ll-AC with a 120V AC Coil Prevention of Unplanned 10/19/79 Re 1 eases of Radi oacti vity All Power Reactor Licensees with an OL or CP All Power Reactor Licensees with an OL or CP All Power Reactor Licensees with an OL or CP All Power Reactor Licensees with an OL or CP
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