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Responds to 790509 ltr requesting info on NRC studies of operating performance of "below average" plants in MI.Study info not endorsed by NRC.NRC authorized development of evaluation methodology.W/supporting documentation.

Accession Number: ML19208B784

Date Released: Saturday, November 7, 2020

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• ML19208B802 - RO 77-023:on 770419,waste gas decay tank lost 10 psig while isolated,violating Tech Specs.Cause unstated. (2 page(s), 5/4/1977)
• ML19208B805 - Corrected copy of RO 77-045:on 770916,found that loss of air supply to containment bldg purge isolation valves will result in depressurization of seal bladders.Caused by valves not being provided w/redundant air supply. (1 page(s), 9/30/1979)
• ML19208B806 - Forwards RO 77-046 & RO 77-048 re svc water pump check valve failure & improper primary coolant low flow instrument settings.W/o encl. (1 page(s), 10/18/1977)
• ML19208B811 - RO 77-47:on 770924,during electrical storm,bus R was de-energized causing complete loss of offsite power & resulting in loss of main condenser cooling water & plant trip.Cause unknown.Tech Spec change will be made. (2 page(s), 10/18/1977)
• ML19208B814 - RO 77-058:on 771125,during normal steady operation,bus R became de-energized causing complete loss of offsite power & resulting in loss of main condenser cooling water.Cause unknown. (2 page(s), 12/16/1977)
• ML19208B816 - LER 78-007/01T-0:on 780313,during sealing of electrical connectors located inside containment,sockets &/or sealing plugs were discovered missing from connectors.Caused by connector holes not being filled during wiring. (2 page(s), 3/27/1978)
• ML19208B818 - LER 78-033/01T-0:on 781025,during 15-day isolation of waste gas decay tank,part of tank contents leaked out.Caused by faulty pressure instrumentation.Instrumentation recalibr. (1 page(s), 11/3/1978)
• ML19208B821 - LER 78-040/01T-0:on 781128,during venting of control tank, leakage from surge tank resulted in gaseous release w/o 15-day holdup time.Cause under evaluation.Rept will be submitted by 780105. (1 page(s), 12/12/1978)
• ML19208B825 - LER 78-040/01X-1:on 781128,during venting of waste gas surge tank,leakage resulted in gaseous release w/o 15-day holdup time.Cause under evaluation.Rept will be issued by 790105, not 780105 as previously reported. (1 page(s), 12/18/1978)
• ML19208B830 - LER 78-041/01T:on 781214,dtermined that insufficient high pressure safety injection flow would be delivered to core in event of small break LOCA.Caused by redundant high pressure safety injection header being valved out of svc. (2 page(s), 12/26/1978)
• ML19208B833 - Forwards RO 77-005. (1 page(s), 2/12/1977)
• ML19208B836 - RO 77-005:on 770111,w/reactor in refueling Mode 6, feedbreaker 11A1 tripped,due to overload.Caused by personnel error & equipment failure.Tech Specs involved will be reviewed by all personnel before 770301. (3 page(s), 2/12/1977)
• ML19208B838 - LER 78-026/01T-0:on 780502,during change from Mode 5 to Mode 4,pumps became inoperable when containment spray pump control switches in pull were in lockout position.Caused by procedural inadequacy & personnel error. (1 page(s), 5/16/1978)
• ML19208B840 - Forwards corrected Pages 1,2 & 4 for rept re lockout of containment spray pump switches while entering Mode 4. (4 page(s), 5/22/1978)
• ML19208B843 - Forwards RO re containment spray pump switches. (1 page(s), 5/16/1978)
• ML19208B845 - RO:on 780502,while entering Mode 4,after planned outage, switches for containment spray pumps were not moved from pull to lockout position.Caused by procedural inadequacy & personnel error. (4 page(s), 5/16/1978)
• ML19208B847 - LER 78-037/01T-0:on 780615,while operating in Mode 1, emergency diesel generators were placed in condition in which neither engine was capable of automatic start.Caused by closing of starting air pilot valves on generator. (7 page(s), 6/29/1978)
• ML19208B848 - Discusses violation of App A Tech Specs,Section 3.8.1, re emergency diesel generators inadvertently being removed from svc during maint. (2 page(s), 6/29/1978)
• ML19208B853 - LER 78-045/03L-0:on 780612,following addition of boric acid to borated water sys,boron injection tank boron concentration found to be below limits.Caused by chemical technician error. (1 page(s), 7/11/1978)