05000362/LER-2001-002
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3622001002R00 - NRC Website | |
U.S. NUCLEAR REGULATORY COMMISSION DOCKET (2) FACLFTY NAME(1) PAGE (3) LER NUMBER 6) 002 I 00 2001 Reactor Vendor: � Combustion Engineering Mode: � Mode 6 — Refueling Power: � N/A Temperature: � N/A Pressure:
� N/A
Background:
The Fuel Handling Building Post-Accident Cleanup Filter System (PACU) (VG) filters airborne radioactive particulates and gases from the area of the fuel pool following a fuel rupture accident. PACU automatically starts on a Fuel Handling Building Isolation Signal (FHIS). PACU, in conjunction with normally operating systems, also provides temperature control in the fuel pool area.
Technical Specification (TS) 3.7.14, Fuel Handling Building Post-Accident Cleanup Filter System, requires two PACU trains to be operable during movement of irradiated fuel assemblies in the Fuel Handling Building. With one train of PACU inoperable, Action A. requires the inoperable train be restored to operable within 7 days. If Action A.
is not met, Action B. requires either (1) the operable train of PACU be placed into service immediately, or (2) the movement of irradiated fuel in the Fuel Handling Building be suspended immediately. Irradiated fuel may be moved indefinitely in Action B. provided the operable train of PACU is operating.
TS 3.0.4 prohibits entry into a mode or other specified condition in the Applicability except when the associated Actions to be entered permit continued operation in the mode or other specified condition in the Applicability for an unlimited period of time. Hence, if a train of PACU is declared inoperable subsequent to the start of moving irradiated fuel, moving irradiated fuel may continue for up to 7 days (Action A.). However, movement of irradiated fuel cannot be commenced with an inoperable train of PACU unless the operable train is first placed into service (Action B. entered).
Description of the Event
On January 24, 2002, SCE, while reviewing TS requirements for the Control Room Emergency Air Cleanup System (CREACUS), recognized that irradiated fuel may have been moved in the Fuel Handling Building contrary to the requirements of the PACU TS 3.7.14 and TS 3.0.4 (AR020101212). SCE's review of fuel movement records, completed on March 8, 2002 (discovery date), discovered the following event.
On January 18, 2001, at about 0743 PST, during the Unit 3 Cycle 11 refueling outage, SCE began moving fuel (new and irradiated) from the Fuel Handling Building to the reactor vessel inside containment. At that time, both trains of PACU were operable. On January 20, 2001, at about 0330 PST, PACU train B was removed from service, placing the unit in TS 3.7.14, Action A. Prior to train B being returned to service, fuel movements were stopped on January 20, 2001 (event date), 1339 PST due to an equipment failure (inverter 3Y004). The inverter was returned to operable, and fuel movement re-started that same day at about 1358 PST. At that time, train B PACU was still inoperable and train A was not placed into service. Consequently, this event is being reported in accordance with 10CFR50.73(a)(2)(i)(B).
FACLITY NAME(1) LER NUMBER (6) DOCKET (2) PAGE (3) U.S. NUCLEAR REGULATORY COMMISSION 2001 05000-362 00 002
Cause of the Event
The event occurred because the requirements of the TSs with respect to PACU and the movement of irradiated fuel in the Fuel Handling Building had not been correctly reflected in a plant procedure (cognizant personnel error).
Corrective Action
- The Unit was in full compliance when the movement of irradiated fuel was completed on January 22, 2001, at approximately 0019 PDT and TS LCO 3.7.14 was no longer Applicable.
- Procedure S023-3-2.11, "Spent Fuel Pool Operations," that controls the movement of irradiated fuel was revised to reflect the correct application of TS 3.7.14 and TS 3.0.4.
- Operating crews will be briefed on the TS and procedural requirements for PACU operability and the movement of irradiated fuel prior to the next refueling outage (Unit 2 Cycle 12 currently scheduled for May 2002.) Safety Significance of the Event PACUs are used to mitigate the consequences of a fuel handling accident in the Fuel Handling Building. However, this event had minimal safety significance because:
- The fuel handling accident analyses do not credit their operation for dose mitigation.
- One train of PACU was operable and available to respond to a fuel handling accident.
- This event was not caused by nor did it result in a Safety System Functional Failure (SSFF). This event did not impact the ability to shut down the Unit or mitigate the consequences of an accident. SCE concludes that there was no increase in calculated Core Damage Frequency or Large Early Release Frequency. This occurrence is categorized "Green" using the latest draft of the Reactor Safety Significance Determination Process (SDP).
Additional Information
- In the past three years, SCE has not reported any similar events with a similar cause.
- If a PACU train is removed from service for less than an operating shift, the activity may not be entered into the computerized LCO tracking system, but administratively tracked in the Operators' Logbook instead. The computerized LCO tracing system was used to identify the event reported herein. The Operators' Logbook was not searched. Consequently, it is possible that on some other occasion(s) similar operations prohibited by TS 3.7.14 and TS 3.0.4 may have been performed. If so, that occurrence(s) would have been limited to a period of one shift or less.