ML20002A139
| ML20002A139 | |
| Person / Time | |
|---|---|
| Site: | 05000000 |
| Issue date: | 04/22/1981 |
| From: | NRC OFFICE OF INSPECTION & ENFORCEMENT (IE) |
| To: | |
| References | |
| IEIN-81-15, NUDOCS 8011040286 | |
| Download: ML20002A139 (2) | |
Text
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SSINS No.:
6835 Accession Ha.:
8011040286 IN 81-15 p
UNITED STATES NUCLEAR REGULATORY COMMISSION i
OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 April 22, 1981 IE Informatien Notice No. 81-15:
DEGRADATION OF AUTOMATIC ECCS ACTUATION CAPABILITY BY ISOLATION OF INSTRUMENT LINES Description of Circumstances:
On March 23, 1981 at Georgia Power Company's iatch Unit 2, an instrument technician, while investigating a drywell low pressure alarm, found that seven of eight ir alation volves were closed.
The eighth valve was found slightly open and was conside"ed as being functionally.losed.
These safety-related valves (also ident.ified as panel or root valves) isolated twelve instruments i
that automatically actuate emergency core cooling systems (ECCS), reactor protection system, and containment isolation systems on high drywell pressure.
The capability for manual actuation of the. affected systems was continuously available from the control room.
However, had a loss-of-coolant accident occurred, all systems would have been actuated by a redundant signal of low reactor water level, except for the automatic depressurization system.
Those valves discovered to be closed were opened, valve alignment checks were per-formed, and no other discrepancies were found.
There isolation valves were incorrectly identified as instrument drain valves and were closed on March 9, 1981 during completion of a valve lineup procedure.
The drain valves that were being closed were on other sdfety related lines that were of the same size and appearance as the high drywell pressure instrument lines that were isolated.
Another event involving closure of some similar isolation valves was recently reported by the Peach Bottom Unit 2 licensee on April 1,1981. The closed valves were found by a licensee employee wh was troubleshooting an intermit-tent drywell pressure switch trouble alarm.
Only one isolation valva was found fully closed, whereas two other valves were found one-dgnth turn open (but considered closed for review of protective system rasponses).
Redundant channels were verified to be operable; thus, no autcmatic protective or emergency cooling system actuation would have been lost from the high drywell pressure signal.
This information is provided as an early notification of c possibly signi-ficant matter that is still under review by the NRC staff.
In case the continuing NRC review finds that specific licensee actions would be appro-priate, an IE bulletin or circular may be issued.
In the interim, we expect that licensees will review this, information for applicability to tht-ir oper-ating procedures, paying particular attention to valve alignment checklists and requirements for independent verification of valve alignments including instrument valves.
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IN 81-15 April 22, 1981 Page 2 of 2 No written response to this information notice is required.
If you need additional information with regard to this matter, contact the Director of the j
appropriate NRC Regional Office.
Attachment:
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l Attachment IN 81-15 April 22, 1981 RECENTLY ISSUED IE INFORMATION NOTICES Information Date of Notice No.
Subiect Issue Issued to 81-14 Potential Overstress of 4/17/81 All power reactor Shafts on Fisher Series facilities with an 9200 Butterfly Valves OL with Expandable T Rings 81-13 Jammed Source Rack in a 4/14/81 Specified Irradiato.-
Gamma Irradiator licensees 81-12 Guidance on Order Issued 3/31/81 All BWR facilities January 9,1981 Regarding with an OL or CP Automatic Control Rod Insertion on Low Control Air Pressure 81-11 Alternate R c 'asertion 3/30/81 All BWR facilities for BWR Scram depresents with an OL or CP a Potential Path for loss of Prim &ry Coolant 81-10 Inadvertant Containment 3/25/81 All power reactor Spray Due to Personnel facilities with an Error OL or CP 81-09 Degradation of Residual 3/26/81 All power reactor Heat Removal (RHR) System facilities with an OL or CP 81-08 Repetitive Failures of 3/20/81 All power reactor Limitorque Operator SNB-4 facilities with an Motor-to-Shaft Key OL or CP 81-07 Potential Problem with 3/16/81 All power reactor Watee-Soluble Purge Dam facilities with an Materials Used During OL or CP Inert Gas Welding 81-06 Failure of ITE Model 3/11/81 All power reactor K-600 circuit Breaker facilities with an OL or CP OL = Operating Licenses CP = Construction Permits s