ML14170A426
| ML14170A426 | |
| Person / Time | |
|---|---|
| Site: | Harris, Brunswick, Robinson  |
| Issue date: | 09/10/1979 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Jackie Jones CAROLINA POWER & LIGHT CO. |
| References | |
| NUDOCS 7909210178 | |
| Download: ML14170A426 (6) | |
Text
NUCLEAR o5UNITED STATES NUCLEAR REGULATORY COMMISSION t;
REGION II 6&
101 MARIETTA ST., N.W., SUITE 3100 ATLANTA, GEORGIA 30303 SEP 10 1979 In Reply Refer To:
RII:JPO 50-325, 4-324 50-400, 50-401 50-402, 50-403 50-261 Carolina Power and Light Company ATTN: J. A. Jones Senior Executive Vice President and Chief Operating Officer 411 Fayetteville Street Raleigh, North Carolina 27602 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 recommendations on this matter, please contact this office.
Sincerely, James P. O'Reilly Director
Enclosures:
- 1.
IE Circular No. 79-18
- 2.
List of IE Circulars issued in the last six months recesto
SEP 10 1979 Carolina Power and Light Company
-2 cc w/encl:
A. C. Tollison, Jr.
Plant Manager Box 458 Southport, North Carolina 28461 R. Parns, Site Manager Post Office Box 101 New Hill, North Carolina 27562 R. B. Starkey, Jr., Plant Manager Post Office Box 790 Hartsville, South Carolina 29550
Accession No: 7908200385 SSINS No. 6830 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C. 20555 September 10, 1979 IE Circular No. 79-18 PROPER 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 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 response 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. 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 to the two-stage Target Rock safety-relief valves.
The second potential problem was recently experienced at the Hatch facility.
The licensee event report indicated that improper assembly of the modified design two-stage valve resulted in preventing the air actuator to function.
IE Circular No. 79-18 September 10, 1979 Page 2 of 2 During the changeover to modify these valves from the previous three-stage type to the current two-stage design, two valves were inadvertently reassembled with the air-actuator angularly displaced. This misalignment restricted the air flow via the air inlet port thereby preventing the safety-relief valve from functioning in the air actuation mode. The misalignment was noted and corrected prior to the return of the reactor to operations.
Recommended Actions for BWR Licensee's Consideration:
All holders of operating licenses for BWR facilities employing Target Rock safety-relief valves should be aware of the potential problems described above.
It is recommended that this matter be reviewed at your facility in the following respects:
- 1.
Verify that the installed Target Rock safety-relief valves include the silicone-nomex diaphragms which have the superior time-temperature environment characteristics and that these diaphragms are periodically replaced in accordance with the most conservative recommendations of the reactor vendor or valve manufacturer.
- 2.
Verify that the thermal insulation on the valve is installed in accordance with the valve manufacturer's recommendation.
- 3.
Verify that procedures are adequate to assure proper assembly of the air actuator, pilot and main disk in accordance with the vendor's installa tion instructions for the two-stage valve.
This Circular is being forwarded for information to all BWR facilities with construction permits and to all other power reactor facilities with an operating license or construction permit. No written response to this Circular is required.
If you need additional information regarding this matter, contact the Director of the appropriate NRC Regional Office.
IE Circular No. 79-18 Enclosure September 10, 1979 Page 1 of 2 LISTING OF IE CIRCULARS ISSUED IN LAST SIX MONTHS Circular Subject Date of Issued to No.
Issued 79-18 Proper Installation of 9/10/79 All Power Reactor Target Rock Safety-Relief Licensees with a CP Valves and/or OL 79-17 Contact Problem in SB-12 8/14/79 All Power Reactor Switches on General Electric Licensees with a CP Company Metalclad Circuit and/or OL Breakers 79-16 Excessive Radiation Exposures 8/16/79 All Radiography To Members Of The General Public Licensees And A Radiographer 79-15 Bursting of High Pressure Hose 8/22/79 All Research Reactors (Correc-and Malfunction of Relief tion)
Valve "0" Ring in Certain Self Contained Breathing Apparatus 79-15 Bursting of High Pressure Hose 8/8/79 All Materials Priority I, and Malfunction of Relief Fuel Cycle and Operating Valve "0" Ring in Certain Self-Power Reactor Licensees Contained Breathing Apparatus 79-14 Unauthorized Procurement and 7/13/79 All Medical Licensees Distribution of XE-133 except Teletheraphy Medical Licensees and to all Radiopharmaceu tical Suppliers 79-13 Replacement of Diesel 7/13/79 All Power Reactor Fire Pump Starting Operating Facilities Contactors and all Utilities having a CP 79-12 Potential Disel Generator 6/28/79 All Power Reactors Turbocharger Problem Operating Facilities and all Utilities having a CP
IE Circular No. 79-18 Enclosure September 10, 1979 Page 2 of 2 LISTING OF IE CIRCULARS ISSUED IN LAST SIX MONTHS Circular Subject Date of Issued to No.
Issue 79-11 Design/Construction 6/27/79 All Applicants Interface Problem for, and Holders of Power Reactor CPs 79-10 Pipefittings Manufactured 6/26/79 All Power Reactor from Unacceptable Material Licensees with a CP and/or OL 79-09 Occurrences of Split or 6/22/79 All Materials Punctured Regulator Diaphragms Priority I, Fuel In Certain Self Contained Cycle and Operating Breathing Apparatus Reactor Licensees 79-08 Attempted Extortion - Low 5/18/79 All Fuel Facilities Enriched Uranium Licensed by NRC 79-07 Unexpected Speed Increase 5/2/79 All Holders of of Reactor Recirculation BWR OL's or CP's MG Set Resulted in Reactor Power Increase 79-06 Failure to Use Syringe 4/19/79 All Holders of and Bottle Shields in Medical Licensees Nuclear Medicine except teletherapy licensees