ML19208D807
| ML19208D807 | |
| Person / Time | |
|---|---|
| Site: | Hatch, Vogtle  |
| Issue date: | 09/10/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | John Miller GEORGIA POWER CO. |
| References | |
| NUDOCS 7910010006 | |
| Download: ML19208D807 (2) | |
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- o, UNITED STATES M - [#f' g,
8 NUCLEAR REGULATORY COMMISSION s/gg o
g REGION il
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o, 101 MARIETTA ST N.W SUITE 3100 b
ATLANTA, GEORGIA 30303 SEP 1 0 1979 In Reply Refer To:
RII:JP0 50-424,q-366 50-321, 5
425 Georgia Power Company Attn:
J. H. Miller, Jr.
Executive Vice President 270 Peachtree Street, N.W.
Atlanta, Georgia 30303 Gentlemen:
The enclosed Circular No. 79-18 is forwarded to you for information. No written response is required.
Should you have any questions related to your understanding of the recom:nendations on this tnatter, please contact this office.
Sincerely, d
James P. O'Reill Director
Enclosures:
1.
IE Circular No. 79-12 2.
List of IE Circulars issued in the last six months 910010006 1057 292
SEP t o 7979 Georgia Power Company cc w/ encl:
M. Msnry, Plant Manager Post Office Box 442 Baxlery, Georgia 31513 C. E. Belflower Site QA Supervisor Post Office Box 442 Baxley,qeorgia 31513 K. M. Gillespie Construction Project Manager Post Office Box 282 Waynesboro, Georgia 30830 E. D. Groover QA Site Supervisor Post Office Box 282 Waynesboro, Georgia 30830 og 1057 293
Accession No: ~108200385 SSINS No. 68??
UNITED STATES NUCLEAR REGULATORY COMMISSION TICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 September 10, 1979 IE Circular No. 79-18 PROPE INSTALLATION OF TARGET ROCK SAFETY-RELIEF VALVES Description of Circumstances:
As a result of NRC monitoring of operating experiences involving the Target Rock safety-relief valve, two potential problems have been identified. One potential problem is that the performance of the valve has been found to be impaired by either excessive or insufficient insulation around the valve body when installed in its service environment. The other potential problem is that improper assembly of the modified valve can result in inoperability of the remote air actuator.
The Target Rock safety-relief valve is a dual purpose valve in that overpressure response is provided by pilot valve action and automatic depressurization (ADS) is provided by a remote air actuator. Valve operation has been found to be affected by the amount of insulation placed around the valve body. A previous IE Bulletin No. 76-06 was issued on July 21, 1976 as a result of operating experiences where excessive insulation was installed on the valve.
The excessive insulation caused excessive heat to be retained producing a higher temperature environment for the elastomeric diaphragm which resulted in accelerated deterioration of the elastomer. Failure of the elastomeric diaphragm, makes the valve inoperable in the power-operation mode (i.e. manual and ADS).
Subsequently, a silicone-nomex diaphragm was developed by the manufacturer to provide a longer life in high temperature environments.
In addition, the IE Bulletin explicitly required that insulation be installed in accordance with the manufacturer's recommendations.
A recent licensee event report from the Monticello a 1.ty identified a potential problem resulting from insufficient insulau i (i.e. just opposite of the condition addressed by IE Bulletin 76-06). Dur. 3 the performance of special testing nf the response to safety-relief valve aperation, a valve was discovered to be exceeding its design delay time for opening. Subsequent inspection an6 testing of the valve revealed that insufficient insulation may cause condensation to accumulate in the pressure venting ports which then results in delaying the opening of the main disk. This slower response time is significant with respect to primary system overpressure and similar transient response analyses. Although the reported event at Monticello involved the three-stage Target Rock safety-relief valves, the requirements for proper amounts of insulation are similarly applicable t valves.
DUPLICATE DOCUMENT The second potential problem was recent:
The licensee event report indicated that Entire document previously design two-stage valve resulted in prev, entered into system under:
ANO V4052o03S5 No. of pages:
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