ML17318A754
| ML17318A754 | |
| Person / Time | |
|---|---|
| Site: | Cook  |
| Issue date: | 05/12/1980 |
| From: | Pappas H NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Dolan J AMERICAN ELECTRIC POWER CO., INC., INDIANA MICHIGAN POWER CO. |
| References | |
| NUDOCS 8005200408 | |
| Download: ML17318A754 (5) | |
Text
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)hlAY i g jggg Docket No. 50-315 Docket No. 50-316 American Electric Power Service Corporation Indiana and Michigan Power Company ATTN:
Mr. John E. Dolan Vice Chairman Engineering and Construction 2 Broadway New York, NY 10004 Gentlmen:
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/encl:
Mr. D. V. Shaller, Plant Manager Central Files
- Director, NRR/DPM
- Director, NRR/DOR PDR I,ocal PDR NSIC TIC Ronald Callen, Michigan Public Service Commission RI as/3p 9/80
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I formation Notice No. 80-20 Znclo.ure 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 1evel 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 far RCS cooling.
2.
A1.1 non-nuclear instrument (NNI) power and Static" Voltage Regulator YAR supplied from 13.8 KV Bus B via HBB."2.
13.8 K Bus A energized but not connected.
RPS and SFAS Channels 1 and 3 being supplied from YAR.
3.
Equipment Out af Service a.
Source Range Channel Z - Surveillance b.
Emergency Diesel Generator 1 Maintenance.
c.
Decay Heat Loop 1 - Haintenance.
4.
Breakers for containmcnt spray and HPI pumps racked out; SE UENCE OF EVENTS 2:00 p.m.
xvzvr Lose of power to Busses E-2 and F-2 (non-essential 480 VAC)
CAUSE/COM.ANTS Ground short on 13.8 KV breaker HBBF2 which caused breaker to open.
This interrupted power to busses E-2 and F-2 which were supplying all non-nuclear instrument (NNI) power, channels 1 and 3
of the Reactor Protection System (RPS) and
.the Safety Features Actuation Signal (SFAS),
the "computer, and much of the control room indicators.
2z00 p.m.
SFAS Level 5 (recircu-Two aut af four logic tripped upozz loss lation mode) actus-of Busses E-2 and F-2.
Actuatian caused Cion.
ECCS pump suction valves from containment sump to open and ECCS pump suction valves from Borated Water Storage Tank to close.
During value travel times, gravity flow path existed from BWST to containment sump.
2zOZ p.m.
Deca/ Heat (law Operator turned aff only operating DH pressure safety in-pump to avoid spillage of RCS water to jection) flow secured containment via the tygon tubing for RCS by operator level indication and open SG manway.
2z33 pnme Parrial restoration of power Power to Bus E"2 and SFAS channels 1 and 3
restored along with one channel of NNI.
This restored all essential power for ECCS.
2:44 p.m.
EVENT CAUSE/CO%ANTS Attempt to reestab-" Started DH pump 1-2 then st'opped it when lish DH flow it was determined that air was in suction line.
Pump secured to prevent damage.
3:34 p.m.
Source Range Channel 2 energized.
4=00 p.m to 4:06 p.m.
Restoration of Busses Busses restored seguentually as efforts (480 VAC) F-2, F-21, progressed to isolate ground fault.
7-22, and F-23 4:25 p.m.
4:46 p.m.
DH flow restored Containment sump pump breakers opened DH pump 1-2 started after venting.
RCS temperature at 170 F. DH flaw bypassing cooler>
Xncore TC's being taken and maximum Precautionary measure to assure containment..
sump water from BWST remained in Sontainment.
Incore TC's range from 161 to 164 F.
5-40 p.m.
Computer returned to Xncore TC's range from 158 to 160 F.
service.
6:24 p.m.
9:50 p.m.
DH flow directed through cooler Power completely res tored RCS cooldown established at less than 25 F per hour.
RCS teurperature at 150 F Inc>>e T<
range from 151 to 158oF.
RCS temperature at approximat;ely 115 F.
STATUS OF DAVIS B SSE 1 AFTER RECOVERY FROM LOSS OF POWER TO BUSSES E-2 AND F-2:
1.
Refueling mode with RCS temperature at 115 7 and level slightly below vessel he o
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 KU bolus A via breaker HAAE2 and Bus F-2 being supplied from 13.8 KV Bus B via breaker HBBF2.
3.
Decay heat loop fi,lied, all tags clear.
Maintenance work restricted so restoration of system will be lass than two hours.
4.
ECCS pump suction valves (DH-9A and DH-9B) from containment sump closed and breakers racked out.
This will prevent the suction of air into the decay
heat loop during a level 5 actuation (recirculation mode) when there is no water in the. sump.
5.
Equipment Out of Service.
Emergency Diesel Generator 1 - maintenance 6.
Breakers for containment spray and HPI pumps acked out.