05000339/LER-2004-002
| Event date: | 05-29-2004 |
|---|---|
| Report date: | 07-19-2004 |
| 3392004002R00 - NRC Website | |
II
FACILITY NAME (1)� DOCKET LER NUMBER 16) PAGE (3) � 1.0 DESCRIPTION OF THE EVENT On May 29, 2004, Unit 2 was in Mode 3, zero percent power, preparing for restart following a refueling outage. Unit 2 reactor coolant temperature and pressure were 540 degrees Fahrenheit and 2246 psig, respectively. As part of the performance for Rod Drop Time Measurement the Control Bank "D" Groups 1 and 2 control rods were being withdrawn from the core. At 0202 hours0.00234 days <br />0.0561 hours <br />3.339947e-4 weeks <br />7.6861e-5 months <br />, the Group Step Counters were declared inoperable as a result of Control Bank "D" Group 1 demand position indicator (EIIS System AA, Component CTR) reading four steps while Control Bank "D" Group 2 demand position indicator was reading one step. At 0210 hours0.00243 days <br />0.0583 hours <br />3.472222e-4 weeks <br />7.9905e-5 months <br />, the reactor trip breakers (RTB) were manually opened in accordance with Technical Requirement 3.1.3 due to a mismatch of the Control Bank "D" Group demand position indicators greater than two steps.
The demand step indicators were inspected for Control Bank "D" Groups 1 and 2 with no problems noted. The RTBs (EIIS BKR) were subsequently tested satisfactorily and closed. The Control Bank "D" Groups 1 and 2 controls were withdrawn two steps, inserted two steps and then positioned back to zero with no problems noted. At 0350 hours0.00405 days <br />0.0972 hours <br />5.787037e-4 weeks <br />1.33175e-4 months <br />, the rod drop time measurements resumed. Rod drop time measurements for the "A" and "C" Control Bank Groups continued and were completed satisfactorily. It was determined the problem with the Control Bank "D" Group 2 demand step counter was the result of the cover not being in its proper position. The cover was snapped closed to its proper position. The RTBs were tested satisfactorily and the rod drop time measurement for Control Bank "D" Groups 1 and 2 control rods resumed. At 1537 hours0.0178 days <br />0.427 hours <br />0.00254 weeks <br />5.848285e-4 months <br />, rod drop time measurements were completed satisfactorily.
was placed on-line at 1112 hours0.0129 days <br />0.309 hours <br />0.00184 weeks <br />4.23116e-4 months <br /> on May 30, 2004.
2.0 SIGNIFICANT SAFETY CONSEQUENCES AND IMPLICATIONS This event posed no significant safety implications because the reactor was subcritical when the RTBs were opened. Compliance with all Technical Requirements was achieved. Therefore, the health and safety of the public were not affected by this event.
An 8-hour non-emergency report was made to the NRC at 0955 hours0.0111 days <br />0.265 hours <br />0.00158 weeks <br />3.633775e-4 months <br /> in accordance with 10 CFR 50.72 (b)(3)(iv)(A). This event is reportable pursuant to 10 CFR 50.73 (a)(2)(iv)(A) for a condition that resulted in an manual actuation of any engineered safety feature including the reactor protection system.
FACILITY NAME (1) DOCKET LER NUMBER r � PAGE (3) 3.0 CAUSE The manual reactor trip was the result of having a mismatch in Group Step Demand Counters. This was the result of the Control Bank "D" Group 2 demand position indicator cover not being in its proper position (i.e., snapped down) such that the counter mechanical cams were not engaged. This position prevented the demand step counter from operating properly. The improper condition of the demand position indicator cover is attributed to worker practices following a previous adjustment.
4.0 IMMEDIATE CORRECTIVE ACTION(S) In each instance the Control Room Operators performed the required actions of the Technical Requirements within the specified times. Troubleshooting of the Control Bank "D" Group 1 and 2 demand position indicators was performed. The Control Bank "D" Group 2 demand position indicator cover was placed in the correct position.
5.0 ADDITIONAL CORRECTIVE ACTIONS A Training Information Bulletin has been developed to heighten awareness regarding the need to snap the demand step counter covers closed. This event will be covered in Continuing Training classes for Operations, Instrument & Controls, and Reactor Engineering. Operations and testing procedures will be enhanced by adding a caution concerning the proper position of the demand step counter cover.
6.0 ACTIONS TO PREVENT RECURRENCE The actions stated above are sufficient to preclude recurrence.
7.0 SIMILAR EVENTS The following events were reported via LERs however, the cause for these events was equipment failure versus an improper position of the demand step counter cover.
LER N2-98-001-00 dated 04/30/98 and LER N2-01-002-00 dated 04/24/01.
8.0 ADDITIONAL INFORMATION At the time of this event Unit 1 was operating at 100 percent power and was not affected by this event.