05000305/LER-2004-005
| Docket Number | |
| Event date: | 11-26-2004 |
|---|---|
| Report date: | 01-25-2005 |
| 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 |
| 3052004005R00 - NRC Website | |
FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6 PAGE (3)
DESCRIPTION
On November 26, 2004, during plant heatup and pressurization at the end of refueling outage R-27, the Reactor Coolant System [AB] (RCS) was pressurized to greater than 1000 psig with the Safety Injection [BQ] (SI) Accumulator [ACC] Isolation Valves [ISV] (SI-20A and SI-20B) closed and their actuator power supply breakers [BKR] tagged off contrary to Technical Specification (TS) 3.3.a.1.B. TS 3.3.a.1.6 requires that "Accumulator isolation valves SI-20A and SI-20B shall be open with their power breakers locked out at or before the Reactor Coolant System pressure exceeds 1000 psig.
During the course of the plant heatup, all pressurizer [PZR] heaters [EHTR] were energized to raise RCS pressure. RCS pressure raised as expected with appropriate indications received. One such indication was annunciator [ANN] 47024E, "SI ACMTR A/B ISOLATION VALVE ABNORMAL", with associated Sequential Events Recorder (SER) [XR] point # 919, "LOCK OPEN ACCUMULATOR VALVES" received at 2347 hours0.0272 days <br />0.652 hours <br />0.00388 weeks <br />8.930335e-4 months <br />.
This alarm actuates at 800 psig. The Alarm Response Procedure (ARP) directs the operator to verify valves are lined up as required per N-SI-33-CL, Appendix A, "Normal Operating Procedure Valve Lineup Checklist".
This Appendix states for RCS pressure less than 1000 psig, the proper position for SI-20A and SI-20B is closed. Thus, no action was taken in response to the annunciator.
The RCS pressure increase continued, as expected, and at 0014 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> on November 26, 2004 reached 1000 psig. Shortly after, the Shift Technical Advisor (STA), conducting a review of plant parameters, noted the position of SI-20A and SI-20B and that RCS pressure was greater than 1000 psig. The STA verified in TS that SI-20A and SI-20B were required to be open for the current plant condition. By this point, RCS pressure was approximately 1100 psig. The N-SI-33-CL, Appendix A, lineup was already in progress with the administrative control cards removed from the S1-20A and S1-20B breakers at 0025 hours2.893519e-4 days <br />0.00694 hours <br />4.133598e-5 weeks <br />9.5125e-6 months <br /> with the breakers in the ON position. The cards were then removed from the SI-20A and SI-20B control switches at 0027 hours3.125e-4 days <br />0.0075 hours <br />4.464286e-5 weeks <br />1.02735e-5 months <br /> with a position of OPEN/AUTO. The completion of N-SI-33-CL, Appendix A, was logged at 0035 hours4.050926e-4 days <br />0.00972 hours <br />5.787037e-5 weeks <br />1.33175e-5 months <br /> with SI-20A/B valves open and their power breakers locked out.
CAUSE OF THE EVENT
The Root Cause of this condition was inadequate management control of operations procedures content, resulting in the presence of an error trap in operating procedure N-0-01. A significant contributing factor was the failure to conduct a pre-job briefing at a level of detail commensurate with management expectations. The purpose of this briefing is to review planned actions, associated limits, TS that are impacted, and other topics as defined on the pre-job brief checklists.
Additional significant contributing factors are the failure to recognize a TS required condition, and a failure to verify assumptions against TS. In these instances, the Senior Reactor Operator (SRO) on shift did not recognize that exceeding 1000 psig with SI-20A and SI-20B closed would violate TS until the condition existed. Further, TS were not reviewed or consulted to verify assumptions; rather the procedure was relied upon to make a judgment relative to TS.
FACILITY NAME (1) DOCKET NUMBER (2) LER NUMBER (6 PAGE (3)
ANALYSIS OF THE EVENT
This event is being reported under 10CFR50.73(a)(2)(i)(B), operation which was prohibited by TS, and 10CFR50.73(a)(2)(v)(D), a condition which could have prevented the fulfillment of the safety function of a system needed to mitigate the consequences of an accident. This event is identified as a Safety System Functional Failure. It does not involve any specific equipment failures.
The SI Accumulators are designed to re-flood the reactor core following a Large Break Loss Of Coolant Accident (LBLOCA). Given the reduced RCS pressure, and resultant reduced stress on RCS piping and components at the time of this event, the likelihood of a LBLOCA is significantly reduced. In addition, the condition was recognized very soon after RCS pressure exceeded 1000 psig and actions were initiated to realign the safety injection system. The total time from exceeding 1000 psig to completing the associated checklist was approximately 20 minutes. This included administrative time to review and document completion of the checklist. This event occurred at the conclusion of a refueling outage, and the time the reactor was shut down prior to the event was 48 days. Based on these factors, decay heat was minimal. Therefore, this event is determined to have a low safety significance.
CORRECTIVE ACTIONS
1. SI Accumulator Isolation Valves SI-20A and SI-20B were opened and procedure N-SI-33-CL APPENDIX A was completed at 0035 hours4.050926e-4 days <br />0.00972 hours <br />5.787037e-5 weeks <br />1.33175e-5 months <br /> on November 26, 2004. TS requirements were satisfied at this time.
2. Procedure N-0-01 was revised on November 30, 2004. The change included a note prior to the critical step regarding the status of the accumulator isolation valves and their power supply breakers. The actions of N-SI-33-CL APPENDIX A are now required to be completed prior to exceeding 975 psig. In addition, a Precaution and Limitation related to the accumulator isolation valve position was added.
3. An Operations Night Order was issued on November 26, 2004 requiring update briefings in the Control Room on a 3-hour interval for the remainder of the startup sequence. Topics covered consisted of the following:
- TS equipment currently out of service.
- Status of ongoing operations work.
- Upcoming operations work and who will be responsible for the task.
- Other work going on in the plant and how it will affect required equipment.
- Upcoming plant mode changes and what equipment will be required to be operable.
- Expectations for hold points.
4. A Corrective Action has been initiated which will evaluate if there are Operations Department training needs regarding initial plant heat-up and associated TS requirements.
FACILITY NAME (1) Kewaunee Nuclear Power Plant DOCKET NUMBER (2) 05000305 YEAR LER NUMBER (6 I REVISION 5. A comprehensive review of operating procedures that provide high level guidance related to configuration control will be performed to verify the procedures contain the requisite hold points, with sufficient margin to TS limits, to preclude inadvertent violation of a limit. This review will consist, at a minimum, of procedures N-0-01, "Plant Startup from Cold Shutdown to Hot Shutdown Conditions", N-0-02, "Plant Startup From Hot Shutdown to 35% Power", N-0-03, "Plant Operation Greater than 35%", N-0-04, "35% Power to Hot Shutdown Condition", and N-0-05, "Plant Cooldown From Hot Shutdown to Cold Shutdown Condition".
SIMILAR EVENTS
None