Semantic search
| Entered date | Event description | |
|---|---|---|
| ENS 41277 | 22 December 2004 09:30:00 | At approximately 04:55 on December 22, 2004, Unit 2 experienced a malfunction of Electro-Hydraulic Control (EHC) system resulting in opening of main turbine bypass valves and resultant loss of reactor pressure. The reactor automatically shutdown on RPS with the completion of a Group I isolation signal (Reactor pressure 850 prig and Reactor mode switch in RUN) resulting in a closure of the Main Steam Isolation Valves (MSIVs). Reactor level lowered to (ECCS) initiation set-point of -48 inches and High Pressure Coolant Injection (HPCI) system and Reactor Core Isolation Coolant (RCIC) system automatically initiated and restored level. When reactor level lowered below the 1 inch set-point, Group II and III Primary Containment Isolation System (PCIS) signals initiated. All Unit parameters are stable and RPS/PCIS/ECCS systems performed as designed. MSIVs remain closed. Reactor level and pressure are stable with HPCI and RCIC systems in control. Group I, II, and III isolations have been reset. The EHC malfunction is presently under investigation by Station Management. All systems functioned as required. The reactor water level is now at 23 inches and stable and the licensee is conducting a slow depressurization to Mode 4 to investigate the EHC system malfunction. The level transients experience during the scram would be expected with the closure of the MSIVs. The licensee has notified the NRC Resident Inspector. |
| ENS 41107 | 9 October 2004 05:13:00 | The following information was obtained from the licensee via facsimile: During the performance of scheduled instrument surveillance testing it was discovered that the Unit 3 High Pressure Coolant Injection (HPCI) pump suction valve from the Condensate Storage Tank (CST) would not automatically close. This valve is designed to automatically close when both Torus suction valves are fully open. The CST suction valve is required to close to support operability of the HPCI System. The CST suction valve was subsequently closed with the Torus suction valves open to allow performance of the HPCI instrumentation testing. After the completion of scheduled instrumentation testing, the HPCI system will be restored to an operable status with pump suction remaining from the Torus and isolated from the CST. The failure of the CST suction valve to auto close is being investigated. The licensee has informed the NRC Resident Inspector. |
| ENS 40973 | 22 August 2004 01:12:00 | The following information was provided by the licensee via facsimile: (The) High Pressure Coolant Injection (HPCI) flow controller malfunctioned resulting in the inability of the HPCI to perform its safety function as a single train system under 10 CFR 50.72 (b)(3)(v). The failure mode for the flow controller is suspected to be a power supply issue, however, the cause has not been confirmed at this time. Unit 2 is in a 14 day technical specification (T.S.) limitation which if exceed results in a unit shutdown ( T.S. 3.5.1 Condition C). The licensee has notified the NRC Resident Inspector.
The purpose of this notification is to retract a previous report made on 8/22/04 at 0112 hours (EN# 40973). Notification of the event to the NRC on 8/22/04 was initially made as a result of declaring the Unit 2 High Pressure Coolant Injection (HPCI) system inoperable when unexpected conditions were found during performance of routine control board checks of HPCI. Specifically, it was observed by the Reactor Operator that the HPCI flow controller would not properly respond to faceplate manipulations. Initially, it was believed that the flow controller power supply may have failed and therefore, the flow controller could not perform its intended function. The HPCI system was not operating at the time of the discovery. Since the initial report, Engineering has determined that the HPCI system was capable of performing its safety function. Although it was determined that the HPCI flow controller faceplate was defective, the set point of the flow controller and the flow controller's ability to automatically control system flow for a design basis event was not affected. A failure analysis of the faceplate was performed. It was determined that keypad contacts on the faceplate were the cause of the degraded faceplate function, but these keypad Contacts did not prevent the flow controller from performing its design function. The flow controller faceplate was replaced by 1410 hours on 8/22/04 (CR 246290). The NRC resident has been informed of the retraction. Notified the Reg 2 RDO (Ogle) |