ML100471104

Diablo Canyon GL 2008-01 Void Intrusion Modifications

ML100471104
Person / Time
Site:	Diablo Canyon
Issue date:	01/22/2010
From:	Lin A Pacific Gas & Electric Co
To:	Office of Nuclear Reactor Regulation
Lyon W, DSSA/SRXB, 415-2897
Shared Package
ML100480102	List: ML100470947 ML100471104 ML100471136 ML100471151
References
GL-08-001
Download: ML100471104 (8)

Text

Diablo Canyon GL 2008-01 Void Intrusion ModificationsAnderson LinDiablo Canyon Power Plant(805) 545-4286 Axle@pge.com NEI WorkshopJanuary 22, 2010 Mitigation Strategy1.Pump Suction : Remove Voids Away From the Active ECCS Flow Paths2.Pump Discharge: Enhance / Increase Isolation Barriers3.System Dynamic Venting: Coming Out of Outage4.System Monitoring: Symptom Based Monitoring 1-A : CCP Suction Modification:

Void Header

-Collect Voids Away From the Active FlowpathSeal Water HxVCTTo SIPs Suction 6"From RCP Seal ReturnTo CCP #38": Fr = 0.18 or 0.264": Fr = 0.98 or 1.38 8"From RHRP CCP Suction Void Header CCP Suction Void Header UT Port 1-B: RHR Pump Suctiona) Air Ingested During RCS Mid-Loop RHR HxRWST RCS Hot LegFr ~ 0.7 1-B: RHR Pump Suctionb) Air Transport During Pump Test RHR HxRWST RCS Hot LegMiniflow Fr ~ 15Hx Tube Fr ~ 1.2 RHR Suction Fr ~ 0.4 1-B: RHR Pump Suctionc) Collect Void Away From Active Flowpath RHR HxRWST RCS Hot LegMiniflow Fr ~ 15Hx Tube Fr ~ 1.2 RHR Suction Fr ~ 0.4 RHR Pump Suction Void Header

2. Discharge Piping -Enhance Isolation From Accumulators & Replace Check ValvesA.Replace 10 AOVs in the test line on the accumulator side with Anchor Darling Manual ValvesB.Replace all 4 SI Check ValvesC.Replace another 9 AOVs, and install 37 Manual Isolation Valvesfor Test Optimization Modifications andToAddBarrierstoEnhancementIsolation(6 and To Add Barriers to Enhancement Isolation (6 isolation valves in between Accumulator and ECCS Lines in most cases)Test Station