ML17053B547
| ML17053B547 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 03/31/1980 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Rhode G NIAGARA MOHAWK POWER CORP. |
| References | |
| NUDOCS 8004150285 | |
| Download: ML17053B547 (6) | |
Text
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Oocket No. 50-410 UNITED STATES NUCLEAR REGULATORY COMMISS(ON REGION I 631 PARK AVENUE KING OF PRUSSIA, PENNSYLVANIA19406 March 31, 1980 Niagara Mohawk Power Corporation ATTN:
Mr.
G.
K.
Rhode Vice President System Pr'oject Management 300 Erie Boulevard, West
- Syracuse, New York,13202 Gentlemen:
The enclosed IE Information Notice No. 80-12, "Instrument Failure Causes Opening of PORV and Block Valve," is forwarded. to you for information.
No written response is required.
If you desire additional information regarding this matter, please contact this office.
Sincerely,
.Boyce H. Grier Oirector
Enclosures:
1.
IE Information No. 80-12 2.
List of Recently Issued IE Information Notices CONTACT:
M.
H.
Baunack (215-337-5253) cc w/encls:
Eugene B. Thomas, Jr., Esquire
0-ENCLOSURE 1 SSINS No.:
6870 Accession No.:
UNITED. STATES 8002280654 NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT MASHINGTON, D. C.
20555 IE Information Notice No.: 80-12 Date:
March 31, 1980 Page 1 of 1 INSTRUMENT FAILURE CAUSES OPENING OF PORV AND BLOCK VALVE Description of Circumstances:
On August 13, 1979, during full, steady-state power operation at the Connecticut Yankee Haddam Neck Plant, the pressurizer power operated relief valve (PORV) and its isolation (block) valve opened as a result of failure of a light source in the sigma bistable of the pressurizer pressure controller.
The failure of the light source was equivalent in control system response to an overpressure condition in the pressurizer.
By system design both PORV and block valves are closed during normal operation and therefore both valves are required to open in response to an overpressure condition.
The 'opening of the PORV
-and block valve allowed the pressurizer pressure to drop from its normal value of'000 psig to 1950 psig before the PORV and block valves could be closed.
The operator immediately overrode the open signal to the valv'es and closed the valves to stop depressurization.
The pressurizer pressure then immediately returned to normal.
The light'source was subsequently replaced in the bistable and the pressure control system was returned to normal.
The licensee reported that failures of light sources in the bistable of this pressure controller and in other similar plant bistables had been experienced previously.
Also, subsequently on February 4, 1980, a spurious signal from the pressure controller caused both PORV and block valve to open.
In both
- events, the operator responded immediately and effectively to limit the conse-quences of the event to a relatively mild pressure transient on the reactor coolant system..
The licensee also indicated that it had changed out the type of bistable with a solid state design which does not depend on a light source and which is expected to be more reliable.
This information is provided as notification of a possibly significant matter.
It is expected that receipients will review the information for possible applicability to their facilities.
No specific action or response is requested at this time. If you have questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
-0
ENCLOSURE 2 0
IE Information Notice No. 80-12 Date:
March 31, '1980 Page 1 of 1 RECENTLY ISSUED IE INFORMATION NOTICES Information Subject Notice No.
Date Issued Issued to 79"37 Cracking in Low Presssure 12/31/79 Turbine Discs
.All Power Reactor Faci-lities with an Operating License (OL) or Construc-tion Permit (CP).
80-01 80-02 Fuel Handling Events 8NBR Water Rod Lower End Plug Wear 1/4/80 1/25/80 All Power Reactor Faci-lities with an OL or CP All BWR Facilities with an OL or CP 80"03 80-04 80-05 Main Turbine Electro-;
1/31/80 hydraulic Control System
, BWR Fuel Exposure in Excess 2/4/80 of Limits Chloride Contamination of' 2/8/80 Safety Related Piping and Components All Power Reactor Faci-lities with an OL or CP All BWR Facilities with an 'OL or CP All Power Reactor Faci-lities with an OL or CP and applicants for a CP 80-06 80-07 4otification of Signif-icant Events Pump Fatigue Cracking 2/27/80 2/29/80 All Power Reactor Faci-lities with an OL, and applicant for OL All Power Reactor Faci-l'ities with an OL or CP 80"08 80-09 80"10 The States Company Sliding.
3/7/80 Link Electrical Terminal Block Possible Occupational Health 3/7/80 Hazard Associated with Closed Cooling Systems for Operating Power Plants Partial Loss of Non-Nuclear 3/7/80 Instrument System Power Sup-ply During Operation All Power Reactor Faci-lities with an OL or CP All Power Reactor Faci-lities with ah OL or CP All Power Reactor Faci-lities with an OL or CP 80-11 Generic Problems With ASCO Yalves in Nuclear.Applica-tions including FIre Pro-tection Systems 3/14/80 All Power Reactor Facil-ities with an OL or CP, Fuel Fabrication and Processing Facilities