05000254/LER-2005-003
| Docket Numbersequential Revmonth Day Year Year Month Day Year N/Anumber No. 05000 | |
| Event date: | 04-05-2005 |
|---|---|
| Report date: | 06-06-2005 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2542005003R00 - NRC Website | |
FACILITY NAME (1)0
- DOCKET NUMBER (2) LER NUMBER (6 PAGE (3) Quad Cities Nuclear Power Station Unit 'I .. .0 05000254 NUMBER NUMBER (It more space is required, use additional copies of NRC Form 366A)(17)
PLANT AND SYSTEM IDENTIFICATION
General Electric - Boiling Water Reactor, 2957 Megawatts Thermal Rated Core Power Energy Industry Identification System (EIIS) codes are identified in the text as [XX].
EVENT IDENTIFICATION
Three Main Steam Safety Valves Outside of Technical Specification Allowed Tolerance A.C CONDITION PRIOR TO EVENT Unit: 1 Event Date: April 5, 2005 Event Time: 1515 hours0.0175 days <br />0.421 hours <br />0.0025 weeks <br />5.764575e-4 months <br /> Reactor Mode: 5. Mode Name: Refueling Power Level: 000% Refueling (5) - Mode switch in the Shutdown or Refuel position with average reactor coolant temperature at any temperature and fuel in the reactor vessel with one or more vessel head closure bolts less than fully tensioned or with the head removed.
B. DESCRIPTION OF EVENT
On April 5, 2005, at 1515 hours0.0175 days <br />0.421 hours <br />0.0025 weeks <br />5.764575e-4 months <br />, Quad Cities Nuclear Power Station was notified that three of the four Main Steam Safety Valves (MSSVs)'[V] [SB] removed from Unit 1 earlier during the Spring 2005 refuel outage (Q1R18, March 21 to April 19, 2005) had been found during as-found testing to have lift set pressures outside of the +/-1% Technical Specification (TS) allowed tolerance. All three of the valves had lift set pressures inside the +/-3% ASME Code tolerance.
All four of the removed valves were replaced during Q1R18 with newly refurbished MSSVs that were certified to be within the +/-1% TS tolerance.
C. CAUSE OF EVENT
The cause of the MSSVs being outside of the TS tolerance is setpoint D.C SAFETY ANALYSIS The safety significance of this event was minimal. All of the four removed MSSVs were found to have a lift set pressure below the TS nominal value. Also, all three of the MSSVs that had lift set pressures that were outside the +/-1% TS tolerance had lift set pressures inside the +/-3% Code tolerance. The cycle specific fuels and transient analyses were performed assuming a +/-3% tolerance. Therefore, the valves were capable of performing the safety function. This condition is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B), which requires reporting of FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6 PAGE (3) ' NUMBER NUMBER .Quad Cities Nuclear Power Station Unit 1 05000254 (If more space Is required, use additional copies of NRC Form 366A)(17) any operation or condition which was prohibited by the plant's TS.
E. CORRECTIVE ACTIONS
All four of the removed valves were replaced during Q1R18 with newly refurbished MSSVs that were certified to be within the +/-1% TS tolerance.
F. PREVIOUS OCCURRENCES
There have been previous instances of MSSVs and Safety/Relief Valves (S/RVs) [RV] being outside of the TS allowed value (+/- 1%). Following the Unit 1 refuel outage in October of 2000 (Q1R16), the S/RV setpoint was 2.203% lower than nameplate, one MSSV setpoint was 2.0643% greater than nameplate, and one MSSV setpoint was 1.20% greater than nameplate. Following the Unit 2 refuel outage in February of 2002 (Q2R16), the S/RV setpoint was 2.026% greater than nameplate, one MSSV setpoint was 2.8% less than nameplate, one MSSV setpoint was 1.8% less than nameplate, and one MSSV setpoint was 1.5% less than nameplate. Following the Unit 1 refuel outage in November of 2002 (Q1R17), the S/RV setpoint was 2.203% greater than nameplate and one MSSV setpoint was 1.2% lower than nameplate. Following the Unit 2 refuel outage in March 2004, the S/RV setpoint was 6.8% greater than nameplate (LER 254/04-001).
For every case except the Q2R17 S/RV, the setpoint was within the code allowable of +/- 3%, and therefore there was no effect on functionality. For the Q2R17 S/RV, a specific assessment was performed to show that the safety valve function was met.
Based on the history described above, Quad Cities Nuclear Power Station is pursuing a revision to the Technical Specification allowable value for the MSSVs and S/RVs to reflect the code allowable.
G. COMPONENT FAILURE DATA
The MSSVs are MODEL# 6'-3777-QA-RT Safety Valves manufactured by Dresser Industries/Consolidated Valve Corporation.