ML19305E775
| ML19305E775 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 05/12/1980 |
| From: | Pappas H NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Bryan J UNION ELECTRIC CO. |
| References | |
| NUDOCS 8005200403 | |
| Download: ML19305E775 (1) | |
Text
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NUCLEAR REGULATORY COMMISSION I
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v GLEN ELLYN,ILLINOls 60137 WAY 12 G80 Docket No. 50-483 Docket No. 50-486 Union Electric Company ATTN:
Mr. John K. Bryan Vice President - Nuclear P. O. Box 149 St. Louis, MO 63166 Gentlemen:
Due to an oversight, the attached " Enclosure A" to IE Information Notice No. 80-20 was omitted from our letter dated May 8,1980.
Sincerely, Helen Pappas, Chief Administrative Branch
Enclosure:
Attachment A to IE Information Notice No. 80-20 cc w/ enc 1:
Mr. W. H. Woer, Manager, Nuclear Construction Central Files Director, NRR/DPM j
Director, NRR/ DOR PDR Local PDR NSIC TIC Region I & IV Ms. K. Drey Mr. Ronald Fluegge, Utility Division, Missouri Public Service Commission
IE Information Notice No. 80-20 Enclosure A i
DAVIS-BESSE EVENT OF APRIL 19. 1980 STATUS OF DAVIS-BESSE 1 PRIOR TO LOSS OF POWER TO BUSSES E-2 AND F-2:
1.
Refueling mode with RCS temperature at 90 F and level slightly below vessel head flange.
Head detensioned with bolts in place.
Manway cover on top of OTSG removed.
Tygon tubing attached to lower vents of RCS hot leg for RCS level indication.
Decay heat loop 2 in service for RCS cooling.
2.
All non-nuclear instrunent (NNI) power and Static Voltage Regulator YAR supplied from 13.8 KV Bus B via HBBF2.
13.8 K Bus A energized but not connected.
RFS and SFAS Channels 1 and 3 being supplied from YAR.
3.
Equipment Out of Service a.
Source Range Channel 2 - Surveillance b.
Emergency Diesel Generator 1 - Maintenance.
c.
Decay Heat Loop 1 - Maintenance.
i 4.
Breakers for containment spray and HPI pumps racked out.
SEQUENCE OF EVENTS TIME EVENT CAUSE/ComfENTS 2:00 p.m.
Loss of power to Ground short on 13.8 KV breaker HBBF2 Busses E-2 and F-2 which caused breaker to open.
This (non-essential 480 interrupted power to busses E-2 and F-2 VAC) which were aupplying all non-nuclear' instrument (NNI) power, channels 1 and 3 of the Reactor Protection Systen (RPS) and
.the Safety Features Actuation Signal (SFAS),
the computer, and much of the control room indicators.
2:00 p.m.
SFAS Level 5 (recircu-Two out of four logic tripped upon loss lation nede) actua-of Busses E-2 and F-2 Actuation caused tion.
ECCS pump suction valves from containment sump to open and ECCS pump suction valves from Borated Water Storage Tank to close.
During valve travel times, gravity flow path existed from BWST to containment sump.
2:02 p.m.
Decay Heat (low operator turned off only operating DH pressure safety in-pump to avoid spill)ge of RCS vater to jection) flow secured containment via ae tygon tubing for RCS by operator level indication and open SG manway.
2:33 p.m.
Partial restoration of power Power to Bus E 2 and SFAS channels 1 and 3 restored along with one channel of NNI.
This restored all esseatial power for ECCS.
=
e f TIME EVENT CAUSE/ COMMENTS 2:44 p.m.
Attempt to reestab-Started DH pu=p 1-2 then stoppad it when lish DH flow it was determined that air was in suction line.
Pump secured to prevent dar. age.
3:34 p.m.
Source Range Channel 2 energized.
4:00 p.m.
Restoration of Busses Busses restored sequentually as efforts to (480 VAC) F-2, F-21, progressed to isolate ground fault.
4:06 p.m.
F-22, and F-23 4:25 p.m.
DH flow restored DH pump 1-2 started af ter venting. RCS temperature at 170 F.DH flew bypassing 18 l'5e. '"" "* ' b * *" 8 ""k*" '"d "" ***""
r 4:46 p.m.
Containment sump Precautionary measure to assure containment pump breakers sump water from BWST remained in gentainment, opened Incore TC's range from 161 to 164 F.
5:40 p.m.
Computer returned to Incore TC's range from 158 to 160 F.
service.
6:24 p.m.
DH flow direcced RCS cooldown established at less than 25 F through cooler per hour.
RCS te erature at 150 F. Incore T.
rangefrom151to$580F.
9:50 p.m.
Power completely RCS temperature at approximately 115 F.
restored STATUS OF DAVIS.BESSE 1 AFTER RECOVERY FROM LOSS OF POWER TO BUSSES E-2 AND F-2:
1.
Refueling mode with RCS temperature at 115 F and level slightly below vessel he flange.
Head detensioned with bolts in place.
Manway cover on top of OTSC removed.
Tygon tubing attached to lower vents of RCS hot leg for RCS level indication.
Decay heat loop 2 in service for RCS cooling.
I 2.
Bus E-2 being supplied from 13.8 KV 3us A via breaker HAAE2 and Bus F-2 being supplied from 13.8 KV Bus B via breaker HBBF2.
l 3.
Decay heat loop filled, all tags clear.
Maintenance work restricted so restoration of system will be less than two hours.
4.
ECCS pump suction valves (DH-9A and DH-93) from containment sump closed and breakers racked out.
This will prevent the suction of air into the decay l
l I
a 4
3-heat loop during a level 5 actuation (recirculation mode) when there is no water in the.aump.
5.
Equipment out of service:
Emergency Diesel Generator 1 - maintenance 6.
Breakers for containment spray and HPI pumps racked out.
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