PNO-II-86-045, on 860627,four PORVs Opened,Dropping Primary Sys Pressure from 2,235 Psi to 702 Psi & Temp from 550 F to 450 F in 6 Minutes.Cause Under Investigation.Valves Closed & Safety Injection Initiated

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• PNO-II-86-045B, on 860628-0701,augmented Insp Team Sent to Plant.Corrective Action Documented in 860630 Confirmatory Action Ltr Being Monitored by NRC Resident Inspectors.Plant at 6% Power