ML19208B307
| ML19208B307 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Byron, Braidwood, Quad Cities, Zion, LaSalle  |
| Issue date: | 09/10/1979 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Brian Lee COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 7909190527 | |
| Download: ML19208B307 (1) | |
Text
((b pn Raouq'o, UNITED STATES
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NUCLEAR REGULATORY COMMISSION E
REGION lli
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799 ROOSEVELT ROAD
'AJ GLEN ELLYN,iLLINOls 60137 o
Dc:ket Nos. 50-10, 50-237, 50-249, 50-254, 50-265, 50-295, 50-304, 50-373, 50-374, 50-454, 50-455, 50-456 and 50-457 Commonwealth Edison Company XTTN:
Mr. Byron Lee, Jr.
Vice President Post Office Box 767 Chicago, IL 60690 Gentlemen:
The enclosed IE Circular No. 79-18 is forwarded to you for information.
No written response is required.
Should you have any questions rela?.ed to your understanding of the re :ommendations on thi; matter, please contact this office.
Sincerely, h fsa n v James G. K M er Director
Enclosures:
1.
IE Circular No. 79-18 2.
List of IE Circulars Issued in the Last Six Months cc w/ enc 1:
Mr. B. B. Stephenson, Mr. R. Cosaro, Project Station Superintendent Superintendent Mr. N. Kalivianakis,
Central Files Station Superintendent Director, NRR/DPM Mr. N. Wandke, Station Director, NRR/ DOR Superintendent PDR Mr. L. J. Burke, Site Local PDR Project Superintendent NSIC Mr. T. E. Quaka, Quality TIC Assurance Supervisor Anthony Roisman, Esq.,
Mr. R. H. Holyoak, Station Attorney
' Superintendent Mr. Dean Hansell, Office Mr. Gunner Sorensen, Site of Assistant Attorney Project Superintendent General
$730.]$
79091905 W
Accessian No: 7908200S95 SSINS No. 6830 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 September 10, 1979 k
f IE Circula'r No. 79-18 OPER 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 oth F potential problem is that improper assembly of the modified valve can res.lt 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 facility identified a potential problem resulting from insufficient insulation (i.e. just opposite of the condition addressed by IE Bulletin 76-06).
During the performance of special testing of the responsi: to safety-relief valve operation, a valve was discovered to be exceeding its design delay time for opening.
Subsequent inspection and 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.
Althougn the reported event at Monticello involved the three-stage Target Rock safety-relief valves, the requirements for proper amounts of insulation are similarly applicable to the two-stage Target Rock safety-relief valves.
The second potential problem was recent1 DUPLICATE DOCUMENT gD g
The licensee event report indicated that design two-stage valve resulted in prevt Entire document previously entered into system under:
ANO 7909200 % 5 No. of pages:
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