ML20004F780
| ML20004F780 | |
| Person / Time | |
|---|---|
| Site: | Humboldt Bay, Palo Verde |
| Issue date: | 03/25/1981 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV) |
| To: | Van Brunt E ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| Shared Package | |
| ML20004F779 | List: |
| References | |
| NUDOCS 8106220340 | |
| Download: ML20004F780 (1) | |
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'o UNITED STATES NUCLEAR REGULATORY COMMISSION o
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I REGION V o
1990 N. CALIFORN'A SOULEVARD SUITE 202.WALNU1 CREEK PLAZA So,s WALNUT CREEK, CALIFCRNIA 94596 March 25, 1981 Docket Nos. 50-528, 50-529, 50-530
- Arizona Public Service' Company
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P. O. Box 21666 Phoenix, Arizona 85036 Attention: Mr. E. E. Van Brunt, Jr.
Vice President, Nuclear Projects Gentlemen:
The enclosed information notice is provided as an early notification of a possibly significant matter.
It is expected that recipients will review the information for possible applicability to their facilities. No specific action or r'sponse is requested at this time.
If further NRC evaluations so indicate, an IE circular or bulletin will be issued to recommend or request specific licensee actions.
If you have questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely, D
R. H. Engelken Director
Enclosures:
1.
IE Irformation Notice No. 81-10 2.
List of Recently Issued IE Information Notices 1
cc w/ enclosures:
F. W. Hartley, APS.
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-8146220.540
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.8011040273-IN 81 '
UNa 2D STATES NUCLEAR REGULATORY COMMISSION 10FFICE.0F INSPECTION AND ENFORCEMENT y
.-WASHINGTON, D.C.-
20555 March 25,: 1981
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, ;IE'Information Notice No. 81-10: -INADVERTENT CONTAINMENT SPRAY DUE TO PERSONNEL' ERROR
) Description of Circumstances:
On February 11, 1981'while in mode 5-(cold shutdown), an auxiliary unit operator at Sequoyah Unit'.1 misunderstood a verbal instruction and opened
- a single. valve in the residual: heat removal (RHR) system.
The opened valve created a direct flow path througn the RHR system from the primary coolant system to the RHR containment spray header. A rapid primary system depres-5 surization to atmospheric pressure resulted, and a' total of about 110,000 gallons'_of water was sprayed'into the containment from the primary-system and from the refueling water storage tank (RWST).
8.icensees'and applicants should be aware of the_following aspects'of this
. event ar.d should take appropriate' steps to prevent a recurrence at their plant.
The auxiliary unit operator did not have adequate training or orientation at the' particulat duty station involved. A single valve at that station is part
~ of the primary coolant system pressure boundary when using the residual heat r
removal (RHR) system for shutdown cooling. Thus, personnel / ad.ninistrative -
problems and a plant design feature combined to cause the event.
Design of the control room annunciators contributed to prolonging the event.
The, panel indicating emergency core cooling system (ECCS) valve positions is oesigned to warn when the ECCS is not properly aligned for the injection (safety) mode.' When the first valve misalignment occurs, one light comes on in an otherwise dark field of indicators, and an alarn sounds and flashes.
However, in the shutdown cooling mode, several valves are not in their injection mode position. Therefore, in the event at Sequoyah, the alarn light had already been on continu'ously for some time, the annunciator was not supposed to operate,'and one more light coming "on" in a valve-position-
. indicating field with several lights already "on" was easily missed. The operators thus failed-to detect the presence of the inadvertently opened
-i Evalve for au least 35 minutes.
]
Lack of-an ECCS initiation procedure for use in the shutdown cooling mode did not significantly delay. recovery from this event, but potentially could have done so had the primary system been at a higher pressure. To provide injection flow for pressurizer level recovery, the operators opened the RHR system
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suction-valve from the RWST, but they neglectea to close the RHR system suction valves 'from the reactor = coolant system (RCS). A proper procedure would require those la'tter. valves to be closed 'to prevent reactor. pressure from seating a
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. March 25, 1981
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" check' valve ^in the~RWST suction line, which would prevent'the injection mode-
.for the low-pressure (RHR) pumps from being effective' and delay recovery from the' event.
2A similarf probl m with 'the borated water storage tank (BWST).~ check: valve 7ccurred at Crystal River.3 on July 16,:1980 while the unit was in Mode-5 with
. the decay heat system in'use for, shutdown cooling.
Improper valve. alignment on the' decay heat system heat exchangers caused'a rapid cooldown of the RCS which re:ulted 'in a loss of. pressurizer level.. -When recovery was attempted by.
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l realigning the decay heat system suction to the BWST, injection flow could aot
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s E be established until RCS pressure-approached. atmospheric conditions since the -
RCS suction: valves remained.open.
- This problem would-be particularly'significant under a LOCA condition with -
. the RCS temperature above boiling.(Mode 4).
The'information herein is being provided as an early notification of a pos-sibly significantinatter that is still under review by the NRC staff. Recip-
.ients should review the.information for possible arplicability to their facilities. If NRC eva.luation so. indicates, further licensee actions may be requested.-
- No written response to this information notice is required.
If you need additional-information regarding this matter, contact the' Director of the appropriate NRC Regional Office.
Attachment:
Recently. issued IE Information Notices.
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Attachm:nt.
IN 81-10 March 25, 1981 RECENTLY ISSUED IE-INFORMATION NOTICES Information Date of Notice No.
Subject Issue Issued to-81-09 Degradation of Residual 3/26/81 S11 power reactor Heat Removal (RHR) System facilities with an -
OL or CP 81-08 Repetitivc Failures of 3/20/81 All power reacto?
facilities with an Limitorque Operator SNB-4.
OL or CP Motor-to-Shaft Key 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 Gcs 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 DegrahedDCSystemat 3/13/81 All power reactor Palisades ~
facilities with an
- OL or CP 81-04 Cracking in Main Steam
-2/27/81 All power reactor Lines facilities with an OL 81-03 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 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.
.80-45 Potential Failure of-12/17/80 All PWR facilities BWR Backup Manual Scram witF an OL or CP Capability 80-44 Actuation of ECCS in the 12/16/80 All PWR facilities Recirculation Mode While with an OL or CP in Hot Shutdown OL = Operating Licenses CP = Construction Permits
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