05000254/LER-2004-003
| Quad Cities Nuclear Power Station | |
| Event date: | 10-08-2004 |
|---|---|
| Report date: | 12-06-2004 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v)(D), Loss of Safety Function - Mitigate the Consequences of an Accident |
| 2542004003R00 - NRC Website | |
FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6 PAGE (3) (If more space is required, use additional copies of NRC Form 366A)(17)
PLANT AND SYSTEM IDENTIFICATION
General Electric - Boiling Water Reactor, 2957 Megawatts Rated Core Thermal Power Energy Industry Identification System (EIIS) codes are identified in the text as [XX].
EVENT IDENTIFICATION
Control Room Emergency Ventilation Test Failure due to Deficient Modification to Hatch Covers
A. CONDITION PRIOR TO EVENT
� Unit: 1 Event Date: October 8, 2004� Event Time: 2120 hours0.0245 days <br />0.589 hours <br />0.00351 weeks <br />8.0666e-4 months <br /> � Reactor Mode: 1 Mode Name: Run�Power Level: 085% Power Operation (1) - Mode switch in the RUN position with average reactor coolant temperature at any temperature.
B. DESCRIPTION OF EVENT
On October 8, 2004, at 0300 hours0.00347 days <br />0.0833 hours <br />4.960317e-4 weeks <br />1.1415e-4 months <br />, it was determined, through a review of previous surveillances, that the Control Room Emergency Ventilation System [VI] Test had not been performed correctly during the last performance in 2002. The Technical Specification (TS) surveillance involves measurement of the pressure differential across the Control Room Emergency zone boundary. For the surveillance to be valid, the flow through the Control Room Emergency Ventilation System (CREVS) must be less than or equal to 2000 standard cubic feet per minute (SCFM). It was later determined that the CREVS test had not been performed correctly in 2000. On March 22, 2000, and April 11, 2002, although the pressure differentials were acceptable (i.e., greater than or equal to 0.125 inches water gauge), the surveillances were performed with the flow at 2002.01 SCFM and 2034.95 SCFM, respectively, making the surveillances invalid. At 0300 hours0.00347 days <br />0.0833 hours <br />4.960317e-4 weeks <br />1.1415e-4 months <br /> on October 8, 2004, TS Surveillance Requirement (SR) 3.0.3 was entered for these missed surveillances.
TS SR 3.0.3 requires the surveillance to be performed within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
On October 8, 2004, at 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br />, the Unit 1 and Unit 2 cable tunnel access hatches were identified as having potentially inadequate seals [SEAL]. At 2120 hours0.0245 days <br />0.589 hours <br />0.00351 weeks <br />8.0666e-4 months <br />, the surveillance was performed with CREVS flow at 1996 SCFM, and the pressure differential was determined to be less than 0.125 inches water gauge. The CREVS was declared inoperable, TS SR 3.0.3 was exited and TS Action 3.7.4.A was entered. At 2158 hours0.025 days <br />0.599 hours <br />0.00357 weeks <br />8.21119e-4 months <br />, an Emergency Notification System call was made in accordance with 10CFR50.72(b)(3)(v)(D) for loss of safety function of a single train system.
FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6 PAGE (3) Quad Cities Nuclear Power Station Unit 1 05000254 , NUMBER NUMBER (If more space Is required, use additional copies of NRC Form 366A)(17) The seals were enhanced, and the pressure differential was determined to be greater than 0.125 inches water gauge. On October 9, 2004, at 0400 hours0.00463 days <br />0.111 hours <br />6.613757e-4 weeks <br />1.522e-4 months <br /> CREVS was declared operable.
C. CAUSE OF EVENT
The root cause of the failure to perform a valid surveillance in 2000 and 2002 was an inadequate review of a procedure change in 1998. The review did not identify that the TS required flow-verification step was being inadvertently removed from the procedure.
The cause of the failure of the surveillance when performed at the required flow was a deficiency in a modification to install new hatch covers in 1999. This modification did not take into account the effect of counterweights installed on the hatch covers to facilitate opening them. The counterweights decrease the weight of the covers on the seal, allowing a slight bow in the hatch covers to affect the integrity of the seal.
For both the procedure change review process and the plant modification process, the controls in place for these processes have improved significantly since the inadequate procedure/modification reviews discussed above occurred. For procedure ' changes, a new Station Qualified Reviewer's Guide has been created and implemented that clarifies roles and responsibilities and reduces the potential for inadequate procedure reviews. For design changes, the Configuration Control Process has been implemented, which includes process improvements that ensure the appropriate review is applied to changes made to the plant.
D. SAFETY ANALYSIS
The safety significance of this event was minimal. The CREVS does not affect reactor safety. Although the flow was slightly outside of the allowable value for a valid surveillance, the surveillance results in 2000 and 2002 did show acceptable positive differential pressure. Additionally, the differential pressure during the failed test on October 8, 2004, remained positive. Therefore, personnel within the Control Room Emergency Zone would not have received significantly more dose than originally calculated in the Control Room dose analysis. This LER is being submitted in accordance with 10CFR50.73(a)(2)(i)(B), operation prohibited by Technical Specifications, and 10CFR50.73(a)(2)(v)(D), condition that could have prevented fulfillment of a safety function.
E. CORRECTIVE ACTIONS
Immediate Actions' Additional gasket material was added to the hatches and the CREVS Test was performed with satisfactory results.
FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6 PAGE (3) Quad Cities Nuclear Power Station Unit 1 05000254 NUMBER� NUMBER (If more space Is required, use additional copies of NRC Form 366A)(17) Corrective Actions to be Completed The Control Room Emergency Ventilation System Test will be revised to ensure the airflow rate is determined to be less than or equal to 2000 SCFM before taking differential pressure measurements.
The use of the counterweights on the cable tunnel access hatches will be evaluated and appropriate actions taken as required.
F. PREVIOUS OCCURRENCES
No recent events involving failure of the Control Room Emergency Zone were identified.
One recent event was identified involving inadequate procedure review of an Operations procedure. LER 02-03-001, "Failure to Reset Residual Heat Removal Injection Valve Containment Isolation signal due to Inadequate Procedural Development and Review," was submitted on March 10, 2003. The corrective actions for LER 265/03-001 could not be expected to prevent this event (CREVS failure) because the 2000 and 2002 surveillances had already been performed prior to submittal of LER 265/03-001.
One recent event involving an inadequate historical modification was identified.
Coolant Injection Loop Select Reactor Low Pressure Switches," was submitted on September 28, 2004. This event involved an undocumented modification performed prior to 1996 that resulted in an out-of-calibration instrument. The corrective actions for LER 254/04-002 could not be expected to prevent this event (CREVS failure) because the 1999 modification to the hatches had already been performed prior to submittal of LER 254/04-002.
G. COMPONENT FAILURE DATA
The hatch covers that failed to seal adequately were manufactured at Quad Cities Nuclear Power Station in accordance with design documents.