ML19340E032
| ML19340E032 | |
| Person / Time | |
|---|---|
| Site: | Farley  |
| Issue date: | 12/16/1980 |
| From: | James O'Reilly NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II) |
| To: | Mcdonald R ALABAMA POWER CO. |
| References | |
| NUDOCS 8101060239 | |
| Download: ML19340E032 (1) | |
Text
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UNITED STATES
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101 MARIETTA S1., N.W.. SUITE 3100 fo' ATLANTA, GEORGI A 30303 Ot.t 16 !gg In Reply Refer To:
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D-348 T 50-364
Alabama Power Company ATTN:
R. P. Mcdonald
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Vice President-Nuclear Generation P. O. Box 2641 Birmingham, AL 35291 Gentlemen:
The enclosed Information 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 t.ime ; however, contingent upon the results of further staff evaluation, a Bulletin or a Circular recommending or requesting specific licensee actions may be issued. If you have any questions regarding this matter, please contact this me.
Sincerely, e
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t v
James P. O'Reilly Director
Enclosures:
1.
IE Information Notice No. 80-44 2.
List of Recently Issued i
Information Notices cc w/ encl:
W. O. Whitt, Executive Vice President F. L. Clayton, Jr., Senior Vice President H. O. Thrash, Manager-Nuclear Generation O. D. Kingsley, Jr., Manager, Nuclear Engineering and Technical Services J. W. McGowan, Manager-Operations Quality Assurance W. G.' Hairston, III, Plant Manager W. C. Petty, Manager-Quality Assurance (Design and Construction) 8101ogg g
SSINS No..
6835
- "I,
. Accession No.
8012160001 IN 80-44 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 December 16, 1980 IE INFORMATION NOTICE NO. 80-44: ACTUATION OF ECCS IN THE RECIRCULATION MODE WHILE IN HOT SHUTDOWN PURPOSE:
The intent of this Information Notice is to alert PWR licensees and holders of construction permits of a potentially generic problem involving inadvertent actuation of the emergency core cooling system (ECCS) in the " Recirculation Mode".
Such an event occurred at the Davis-Besse Nuclear Power Station (Docket No. 50-346) on December 5, 1980. The plant was in a hot shutdown mode of opera-tion at the time of the event and was undergoing certain maintenance activities as described below.
DISCUSSION:
Just prior to the inadvertent actuation of the ECCS, the licensee was attempt-ing to isolate electrical shorts and/or grounds in the Safety Features Actua-tion System (SFAS).
Towards this end, A-C power had 1.een removed from Channel 3 of the SFAS.
Upon reenergizing Channel 3 it was noted that an indicating lamp was out; therefore, an attempt was made to replace the failed lamp with a spare unit.
While removing a lamp from a spare output slot in a Channel 3 chassis, an arc was drawn between the lamp and the module chassis.
This arcing was apparent-ly due to a combination of shorts or grounds in the SFAS, which toupled with the " common" connection between Channel 1 and 3 resulted in the loss of a power supply in Channel 1.
Since all the bistable trips in Channel 3 had not been completely reset, and since a power supply to Channel I was lost, SFAS Levels 1, 2, 3 and 5 were actuated by the two-out-of four actuation logic.
Since SFAS Level 5 indicates that the Borated Water Storage Tank (BWST) is at a low level, the ECCS was placed in a recirculation rade (i.e., the ECCS suction was aligned to the emergency containment sump.)
In order to place the ECCS system in the recirculation mode, the supply valves i
leading to the Decay Heat Removal (DHR) pumps from the BWST start closing after those in the ECCS line and from the containment emergency sump fully open.
l Thus, during this valve transition period, a flow path existed to the reactor coolant system (RCS) via the BWST and the ECCS pumping system (i.e., the DHR pumps); however, since the RCS pressure was higher tran that of the pumping i
system (2100 vs. 1600 psig) no BWST water was pumped into the RCS.
- Rather, during the valve transition time of about 1-1/2 minutes, approximately 15,000 gallons of borated water was drained from the BWST to the cont.iinment emergency sump.
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IN 80-64 4
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December 16, 1980 Page 2 of 2 4
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The Davis-Besse Nuclear Power Station has experienced several events during the past three and one-half years which have either degraded the DHR system or caused a temporary interruption of DHR operation.
Of these, the one most closely paralleling the event described above occurred on April 19, 1980.
(See IE Infor-mation Notice 80-20, " Loss of Decay Heat Removal Operability at Davis Besse Unit 1 While in A Refueling Mode" dated May 8, 1980 and IE Bulletin No. 80-12,
" Decay Heat Removal System Operability" dated May 9, 1980.) During the Decem-ber 5, 1980 event, the plant was in a hot shutdown mode with RCS pressure at approximately 2100 psig; therefore, the operator was able to promptly trip the DHR pumps, thereby precluding air entrapment in the system or pump damage.
In contrast, the April 19, 1980 event occurred while the plant was in a quasi refueling mode (i.e., the reactor head was in place but detensioned, RCS water level was below the steam generator's bottom plate, the RCS was vented to the atmosphere by an open manhole at the top of the steam generator, and decay heat was being removed by one DHR system).
Since the DHR pump was being used to remove decay heat during the April 19 event, it was left running for approxi-i mately two minutes after the pump had been aligned to the recirculation mode of operation, and tripped when water was discharged from a temporary tygon line.
Since the DHR system was the only system available for decay heat removal, the DHR pump was restarted approximately forty minutes later; however, it was tripped shortly thereafter when it was determined that there was air in the suction line of the system.
In all, the April 19, 1980 event required approx-imately two and one-half hours to vent the DHR system and reestablish uRR flow.
As a consequence of the relatively long recovery time, the temperature limit specified in the Technical Specification for the refueling mode of opera-tion was exceeded during the April 19, 1980 event.
The above events illustrate means whereby the integrity of a major ECCS system can be jeopardized by inadvertently or prematurely aligning the ECCS to the recirculation mode of operation. The major concern in such cases is that the DHR pumps could become air bound if their suction lines are aligrad to a dry s u.mp.
At best, with the pumps air bound, the pump motor would trip automatically or could be tripped manually before any damage occurred, in which case flow could be established after the system is vented; at worst, the pumps could be damaged and become inoperable, in which case the active portion of the ECCS would not be available, if needed at that time.
This Information Notice is provided as an early notification of a possibly signi-ficant matter that is still undar review by the NRC staff.
Recipients should re-view the information for possible applicability to their facilities.
No specific action or response is requested at this time; however, if NRC evaluations so indicate, further licensee actions may be requested or required.
If you have any question regarding this matter, please contact the director of the appropriate NRC Regional Office.
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IN 80-44 i
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- December 16, 1980 RECENTLY ISSUED IE INFORMATION NOTICES r
1 I
l Information Date of Notice No.
Subject Issue Issued to 4
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80-44 Actuation of ECCS in the 12/16/80 All PWR facilities Recirculation Mode While with aa OL or CP in Hot Shutdown 80-43 Failures of the Continuous 12/5/80 All power reactor Water Level Monitor for facilities with OL the Scram Discharge Volume or CP at Dresden Unit No. 2 80-42 Effect of Radiation on 11/24/80 All power reactor Hydraulic Snubber Fluid facilities with OL or CP 80-41 Failure of Swing Check 11/10/80 All power reactor Valve in the Decay Heat facilities with-an OL Removal System at Davis-or CP Besse Unit No. 1 I
80-40 Excessive Nitrogen Supply 11/10/80 All power reactor Pressure Actuates Safety-facilities with j
Relief Valve Operation to OL or CP Cause Reactor Depressur-ization
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80-39 Malfunctions of Solenoid 10/31/80 All light. water reactor Valves Manufactured By facilities with Valcor Engineering Corporation OLs or cps 80-38 Cracking in Charging Pump 10/30/80 All PWR facilities Casing Cladding with an OL or CP 80-37 Containment Cooler Leaks 10/24/80 All_ power reactor and Reactor Cavity facilities with Flooding at Indian Point OLs or cps Unit 2 80-36 Failure of Steam 10/10/80 All power reactor Generator Support Bolting facilities with OLs or cps 80-35 Leaking and Dislodged 10/10/80 All categories G and i
Iodine-124 Implant Seeds G1 medical licensees 80-34 Boron Dilution of Reactor 9/26/80 All PWR Coolant During Steam facilities with Generator Decontamination OLs OL = Operating Licenses CP = Construction Permits
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