ML19351A038
| ML19351A038 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay |
| Issue date: | 03/30/1981 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | AFFILIATION NOT ASSIGNED |
| Shared Package | |
| ML19351A036 | List: |
| References | |
| NUDOCS 8106250081 | |
| Download: ML19351A038 (1) | |
Text
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UNITED STATES
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NUCLEAR REGULATORY COMMISSION
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REGION V
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1990 N. CALIFORNIA BOULEVARD g ** %/
,o SUITE 202. WALNUT OR EEX PLAZA m
WALNUT CREEX, CALIFORNIA 94396 a
March 30, 1981 O
Gentlemen:
The enclosed Infcivation Notice provides early notification of an event that may have safety significance. Accordingly, you should review the Information Notice for possible applicability to your facility.
No specific action or response is requested at this time; however, contingent on the results of further staff evaluation, a bulletin or a circular recomending or requesting specific licensee actions may be issued.
If you have any question regarding this matter, please contact the Director of the appropriate NRC l
Regional Office.
Sincerely, h
R. H. Engelken Director
Enclosure:
IE Information Notice No. 81-11 8106 250 0 Fl
SSINS No.: 6835 Accession No.:
8011040266 IN 81-11 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 March 30, 1981 IE Information Notice No. 81-11: ALTERNATE R3D INSERTION FOR BWR SCRAM REPRESENTS A POTENTIAL PATH FOR LOSS OF PRIMARY COOLANT Description of Circumstances:
During an engineering evaluation of the scram discharge air system in response to recently issued NRC requirements, the Boston Edison Company identified a potential path for loss of primary coolant at its Pilgrim Nuclear Power Station.
The licensee found that the installed location of an anticipated transient without scram (ATWS) alternate rod insertion (ARI) solenoid valve could cause insertion of controi rods without an associated closure of the scram discharge volume vent and drain valves. The loss of coolant could then follow an ARI actuation through the open vent and drain valves to the reactor building equipment drain tank and then to the reactor building sump. The rate of on 3 to 4 gpm per drive for 145 control rod drives)pproximately 500 gpm (based coolant loss through the inserted drives could be a that would be released by the open vent and drain valves. This loss rate is well within the 4250 gpm capability of the high pressure coolant injection (HPCI) system. However, the 400 gpm capability of the reactor core isolation cooling (RCIC) system would need the 100'gpm of the CRD pumps to maintain level.
The alternate rod insertion installation was completed at the Pilgrim BWR during the refueling outage ending in May 1980. The installation was intended to permit dumping the air header supplying the scram valves. This function is similar _to that provided by the backup scram valves, and it provides a means for inserting the control rods in the event of an ATWS that includes failure of the reactor protection system. The testing of the ARI installation at Pilgrim apparently failed to confirm vent and drain valve function.
Following identification of the potential path for loss of primary coolant, the licensee reviewed plant procedures to assure that until system modifi-cations could be completed, immediate operator actions during an ATWS event would include closing the scram discharge vent and drain valves.
It is noted that instrumentation installed in the scram discharge header in response to Bulletin 80-17 and the instrumented volume level switches should alert the reactor operator to the presence of reactor coolant following ARI actuation.
The licensee modified the system during a scheduled outage in February,1981 to cause the scram discharge volume vent and drain valves to close in the event of ARI actuation.
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IN 81-11 March 30, 1981 Page 2 of 2 Discussion with General Electric indicates that they plan to provide pertinent information to operating BWR licensees regarding the described potential path for loss of' primary coolant.
This information is provided as a notification of a possibly significant matter which is still undtr review by the NRC staff.
In case the continuing NRC review finds that specific licensee actions would be appropriate, an IE
' bulletin or circular may be issued.
In the interim, we expect that BWR licensees will review this information for applicability to their facilities.
Licensee.testirig of the ARI installation should also be reexamined to confirm that vent and drain valves close as a direct result of ARI actuation.
No written response to this.information notice is required.
If you need additioril 'infcrmation regarding this matter, please contact the Director of the aopropriate NRC Regional Office.
Attachnent:
Re:ently istued IE Information Notices 9
L
s Attachment IN 81 March 30, 1981 RECENTLY ISSUED IE INFORMATION NOTICES Information -
Date of Notice No.
Subject Issue Issued to 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 Water-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 81-05 Degraded DC System at 3/13/81 All power reactor Palisades facilities with an OL or CP 04 Cracking in Main Steam 2/27/81 All power reactor Lines facilities with an OL 4
'81 Checklist for Licensees 2/12/81 All power reactor Making Notifications of facilities with an Significant Events in OL Accordance with 10 CFR 50.72 l
81-02 Transportation of 1/23/81 All Radiography Radiography Devices licensees 81-01 Possible Failures of 1/16/81 All power reactor General Electric Type facilities with an HFA Relays OL or CP.
OL = Operating Licenses CP e Construction Permits N -
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