05000499/LER-2005-005
| Docket Number Sequential Revmonth Day Year Year Month Day Yearnumber No. 05000 | |
| Event date: | 10-19-2005 |
|---|---|
| Report date: | 12-21-2005 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(i)(b) |
| Initial Reporting | |
| 4992005005R00 - NRC Website | |
I.�DESCRIPTION OF REPORTABLE EVENT
A. REPORTABLE EVENT CLASSIFICATION
This event is reportable pursuant to 1-0 CFR 50.73(a)(2)(i)(B) as a condition prohibited by Technical Specifications.
B. PLANT OPERATING CONDITIONS PRIOR TO THE EVENT
Unit 2 was shutdown, with core reload in progress at the time of the event.
C. STATUS OF STRUCTURES, SYSTEMS, OR COMPONENTS THAT WERE INOPERABLE
AT THE START OF THE EVENT AND THAT CONTRIBUTED TO THE EVENT
As discussed below, 125 VDC Switchboard E2C11 was de-energized as part of a planned outage, which caused the Fuel Handling Building (FHB) Heating, Ventilation, and Air Conditioning (HVAC) system actuation relays to be inoperable. There were no additional structures, systems, or components that were inoperable at the start of the event that contributed to the event.
D. NARRATIVE SUMMARY OF THE EVENT, INCLUDING DATES AND APPROXIMATE
TIMES
On October 17, 2005 at 0819 hours0.00948 days <br />0.228 hours <br />0.00135 weeks <br />3.116295e-4 months <br />, Train C FHB HVAC was declared inoperable as part of a planned C Train AC electrical bus outage, and Technical Specification 3.9.12 Action a.
recommenced Core Alterations after being stopped for Refueling Machine repairs. At the time Core Alterations resumed, all Technical Specifications (TS) in Section 9 "Refueling" and the applicable portion of Section 3, "Instrumentation" were being met. At approximately 0950 hours0.011 days <br />0.264 hours <br />0.00157 weeks <br />3.61475e-4 months <br />, Class 1 E 125 VDC Switchboard E2C11 was removed from service as part of Fuel Handling Building (FHB). The Train C FHB HVAC actuation relays are located in Relay Rack (RR) 145C and are powered from 125V DC Panel 039C, which is in turn powered from Switchboard E2C11. These relays require DC power to automatically place the FHB HVAC in the Emergency mode and would not have actuated with Switchboard E2C11 de-energized. Additionally, although Train C FHB HVAC was already inoperable per TS 3.9.12, the FHB HVAC system was not placed in Emergency Recirculation mode as required by TS 3.3.2. At approximately 1259 hours0.0146 days <br />0.35 hours <br />0.00208 weeks <br />4.790495e-4 months <br />, Switchboard E2C11 was returned to service.
On October 22, 2005 at approximately 2055 hours0.0238 days <br />0.571 hours <br />0.0034 weeks <br />7.819275e-4 months <br />, the night shift Atypical Condition Evaluator (a licensed Senior Reactor Operator assigned to evaluate outage activities for atypical plant conditions) identified that TS 3.3.2 Items 11 a and 11 b (FHB HVAC actuation relays) Actions 29 and 30 were not entered when E2C11 was de-energized on .
October 19, 2005. These actions would have required the C Train of FHB HVAC to be declared inoperable (which had already been done on October 17, 2005 as a result of the Train C AC electrical outage) and placing the FHB HVAC system in the Emergency Recirculation mode of operation. Also, the Atypical Condition Evaluator reviewed the outage work associated with Switchboards E2A11 and E2B11, which had been removed from service during two previous Electrical Bus Outages. When E2A11 was removed from service between 1402 and 1610 hours0.0186 days <br />0.447 hours <br />0.00266 weeks <br />6.12605e-4 months <br /> on October 5, 2005, there were no Spent Fuel Pool (SFP) activities in progress. Switchboard E2B11 was removed from service on October 9, 2005 at 0800 hours0.00926 days <br />0.222 hours <br />0.00132 weeks <br />3.044e-4 months <br /> and returned to service October 10, 2005 at 1350 hours0.0156 days <br />0.375 hours <br />0.00223 weeks <br />5.13675e-4 months <br />. During the period of time E2B11 was out of service, all Technical Specification actions were being met.
E.�THE METHOD OF DISCOVERY OF EACH COMPONENT OR SYSTEM FAILURE, OR
PROCEDURAL OR PERSONNEL ERROR
There were no failed components. As stated above, the TS non-compliance was discovered during a review of outage work.
II.�COMPONENT OR SYSTEM FAILURES
A. FAILURE MODE, MECHANISM, AND EFFECTS OF EACH FAILED COMPONENT
There were no failed components.
B. CAUSE OF EACH COMPONENT OR SYSTEM FAILURE
There were no failed components.
C. SYSTEMS OR SECONDARY FUNCTIONS THAT WERE AFFECTED BY FAILURE OF
COMPONENTS WITH MULTIPLE FUNCTIONS
There were no failed components.
D. FAILED COMPONENT INFORMATION
There were no failed components.
III.�ANALYSIS OF THE EVENT A.�SAFETY SYSTEM RESPONSES THAT OCCURRED Not applicable; this Licensee Event Report documents a TS non-compliance.
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B. DURATION OF SAFETY SYSTEM TRAIN INOPERABILITY
As described above, the Train C FHB actuation relays were inoperable for approximately 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />, however the A and B Trains remained operable and capable of providing the required FHB HVAC emergency recirculation function.
C. SAFETY CONSEQUENCES AND IMPLICATIONS
This event is considered significant because a TS violation occurred. However, because the A and B Trains of FHB HVAC (including actuation logic capability) remained operable, the ability of the FHB HVAC system to automatically respond to a fuel handling accident was not impaired during a time period when fuel movement was in progress.
This event did not adversely affect the safety of the public or station personnel. There were no radiological consequences as a result of this event.
IV. CAUSE OF THE EVENT
The root cause of this event is the over-reliance on highly qualified and experienced individuals to plan and schedule Electrical Bus Outages and the failure to develop and implement procedures to provide guidance for these evolutions. The development of detailed guidance for these activities has not been considered a station priority because the number and significance of events during Electrical Bus Outages have been very low. In the past, Electrical Bus Outage activities have been successfully performed using the knowledge, planning, and scheduling of the Work Window Manager, Electrical (WWME).� A contributing cause to the event is that the Senior Reactor Operators (SROs) responsible to ensure TS compliance did not identify that removing E2C11 from service would result in a Technical Specification 3.3.2 entry. The WWME's coworkers and peers reviewed the Electrical Bus Outage plans provided by the WWME, however, they did not scrutinize the details against the requirements of TS 3.3.2 or the Technical Requirements Manual.
V. CORRECTIVE ACTIONS
1. STP will develop a program procedure to control the development of procedures for de- energizing each individual electrical bus, to be used when removing a bus from service to support maintenance.
2. A review of TS 3.3.2 will be included in Licensed Operator Requalification Training prior to the next refueling outage regarding DC-powered actuation relay circuits and their TS applicability during Modes 5 and 6.
- VI.�PREVIOUS SIMILAR EVENTS There have been no previous similar Licensee Event Reports.
X.�ADDITIONAL INFORMATION STP plans to submit a License Amendment Request which better clarifies the Mode 5 and 6 requirements for the FHB actuation relays.