ML19305E746
| ML19305E746 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Byron, Braidwood, Quad Cities, Zion, LaSalle  |
| Issue date: | 05/12/1980 |
| From: | Pappas H NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Reed C COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 8005200348 | |
| Download: ML19305E746 (1) | |
Text
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UNITED STATES lC l 'i NUCLEAR REGULATORY COMMISSION 3
b :E REGION 111
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o 799 ROOSEVELT R 1AD g
c Eu Ettvu. ittisoi.isoia7 IMAY 121980 Docket Nos. 50-10, 50-237, 50-249, 50-254, 50-265, 50-295, 50-304, 50-373, 50-374, 50-454, 50-455, 50-456 and 50-457 Commonwealth Edison Company ATTN:
Mr. Cordell Reed Vice President Post Office Box 767 Chicago, IL 60690 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/ encl:
Mr. D. L. Peoples, Director Mr. Gunner Sorensen, Site of Nuclear Licensing Project Superintendent Mr. B. B. Stephenson, Mr. R. Cosaro, Project Station Superintendent Superintendent Mr. N. Kalivianakis, Central Files Station Superintendent Director, NRR/DPM Mr. N. Wandke, Station Director, NRR/ DOR Superintendent PDR Mr. L. J. Burke, Site Local PDR Project Superintendent NSIC Mr. T. E. Quaka, Quality TIC Assurance Supervisor Mr. Dean Hansell, Office Mr. R. H. Holyoak, Station of Assistant Attorney Superintendent General
7 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.
Read 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 instrument (NNI) power and Static Voltage Regulator YAR supplied from 13.8 KV Bus B via HSBF2.
13.8 K Bus A energized but not consected.
RPS and SFAS Channels 1 and 3 being supplied from YAR.
j 3.
Equipment out of Service i
a.
Source Ranga Channel 2 - Surveillance b.
Emergency Diesel Generator 1 - Maintenance.
c.
Decay Heat Loop 1 - Maintenance.
4.
Breakers for containment spray and EPI pumps racked out.
SEQUENCE OF EVENTS TIME _
EVENT CAUSE/ COMMENTS 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 supplyir; 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.
2:00 p.m.
SFAS Level 5 (recircu-Two out of four logic tripped upon loss lation ocde) 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 spillage of RCS water to jection) flow secured containment via the tygon tubing for RCS by operator level indication and open SG manway.
l l
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 NSI. This restored all essential power for ECCS.
=
TIME EVENT 2:44 p.m.
Attempt to.reestab- __
CAUSE/ COMMENTS 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.
4:00 p.m.
Restoration of Busses Busses restored sequentually as efforts (480 VAC) F-2, F-21, progressed to isolate ground fault, to l
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 i
18 1756r. '"" "* ' b'1"8 ""**" '"d "'***""
4:46 p.m.
Containment sump Precautionary measure to assure containment.
pump breakers sump water from BWST remained in gentainment, t
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 te erature at 150 F. Incare T4 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. Hesd detrusioned with bolts in place.
Manway cover on top of OTSC removed.
Tygon '.ubing 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 HAAE2 and Bus F-2 being supplied from 13.8 KV Bus 3 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-9B) frem containment sump closed and breakers racked out.
This uill prevent the suction of air into the decay I
+
t l '
heat loop during a level 5 actuation (recirculation mode) when there is no water in the. sump.
t 5.
Equipment out of Service:
Emergency Diesel Generator 1 - maintenance 6.
Breakers for containment spray and HPI pumps racked out, J
9 e
4 6
-.