ML19305E737
| ML19305E737 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 05/12/1980 |
| From: | Pappas H NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Crouse R TOLEDO EDISON CO. |
| References | |
| NUDOCS 8005200338 | |
| Download: ML19305E737 (1) | |
Text
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UNITED STATES 8 %
NUCLEAR REGULATORY COMMISSION n
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o 799 ROOSEVELT ROAD 8
GLEN ELLYN,ILLINOls 60137 3
j Docket No. 50-346 080 Toledo Edison Company ATTN:
Mr. Richard P. Crouse Vice President Nuclear Edison Plaza 300 Madison Avenue Toledo, OH 43652 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. T. Murray, Station Superintendent Central Files Director, NRR/DPM Director, NRR/ DOR PDR Local PDR NSIC TIC Harold W. Kohn, Power Siting Commission Helen W. Evans, State of Ohio
IE Information Notice No. 80-20 Enclosure A 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 1 wer vents of RCS hot leg for RCS level indication.
Decay heat loop 2 in service for RCS cooling.
2.
All non-nuclear instrument (NNI) power and Static Voltage Regulator YAR supplied from 13.8 KV Bus B via HBBF2.
13.8 K Bur, A energized but not connected.
RPS 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.
Lecay Heat Loop 1 - Maintenance.
4.
Breakers for containment spray and HPI pumps racked out.
__ SEQUENCE OF EVENTS TIME EVENT CAUSE/ COMMENTS 2:00 p.m.
Loos cf 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 supplying all non-nuclear' instrument (NNI) power, channels 1 and 3 of the Reactor Protection System (RPS) and l
.the Safety Features Actuation Signal (SFAS),
the computer, and much of the control room l
indicators.
2:00 p.m.
SEAS Level 5 (recircu-Two out of four logic tripped upon loss lation node) actua-of Busses E-2 and F-2 Actuation caused tion.
ECCS pump suction valves from centainment 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 spillage of RCS water to jection) flow secured containment via the tygon tubing for RCS i
t 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 551.
This restored all essential power for ECCS.
1
- TIME EVENT CAUSE/ COMMENTS 2:44 p.m.
Attempt to reestab-Started DH pu=p 1-2 then stopped it when lish DH flow it was determined that air was in suction line.
Pump secured to prevent da= age.
3:34 p.m.
Source Range Channel 2 energized, i
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 flow bypassing 18 176e. '"" "* TC'
- b * *"8 ""k*" '"d ""***""
r 4:46 p.m.
Containment sump Precautionary measure to assure containment pump breakers sump water from BWST remained in gontainment.
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 directed RCS cooldown established at less than 25 F through cooler per hour.
RCS temerature at 150 F. Incore Ti range from 151 to U80F.
9:50 p.m.
Power completely RCS temperature at approximately 115 F.
restored STATUS OF DAVIS-BESSE 1 AFTER RECOVERY FROM LOSS OF p0RER 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.
Hanway 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.
2.
Bus E-2 being supplied from 13.8 KV 3us A via breaker RAAE2 and Bus F-2 being supplied from 13.8 KV Bus B via breaker HBBF2.
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 l
breakers racked out.
This will prevent the suction of air into the decay l
J heat loop during a level 5 actuation (recirculation mode) when there is 1
no water in the sump.
5.
Equipment out of Service:
l Emergency Diesel Generator 1 - maintenance 6.
Breakers for containment spray and HFI pumps racked out.
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