05000247/LER-2007-003

LER-2007-003, Plant in a Condition Prohibited by Technical Specifications due to Operation With Control Room Ventilation System High Flow

Docket Number
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
2472007003R00 - NRC Website

Note:� The Energy Industry Identification System Codes are identified within the brackets {

DESCRIPTION OF EVENT

On January 3, 2007 at approximately 1950 hours0.0226 days <br />0.542 hours <br />0.00322 weeks <br />7.41975e-4 months <br />, with steady state reactor power at 100 percent, Indian Point Energy Center (IPEC) determined that the Control Room Ventilation System (CRVS) booster fans were exceeding the required flow range of 2000 cfm ±10 percent. The CRVS was considered inoperable at the time for testing and Technical Specification (TS) 3.7.10, Condition B for two CRVS trains inoperable had been entered. The CRVS was returned to operability on January 4, 2007. Condition Report IP2-2007- 00040 documents this event. This event was determined to be reportable under 10 CFR 50.73(a)(2)(i)(B) on January 31, 2007 during a subsequent review of results of laboratory testing of the CRVS charcoal.

Condition Report 1P2-2007-00130 documents this event.

The charcoal is in the CRVS and is part of the CR Heating, Ventilating, and Air Conditioning (HVAC) System {VI}. The primary function of the CRVS is to ensure that iodine released during a radiological event can be removed from the Control Room (CR) {VI} in order to maintain the habitability of the CR. TS Surveillance Requirement 3.7.10.3 requires CRVS testing per the Ventilation System Testing Program (VFTP) program found in TS 5.5.9. The VFTP specifies in place testing of CRVS pressure drop, in place testing of the penetration and bypass of the high efficiency particulates air (HEPA) filters {FLT} and charcoal filters, and laboratory testing of charcoal samples. All testing is at 2000 cfm ± 10 percent.

On January 3, 2007, following Procedure 2PT-EM13, a CRVS charcoal sample was removed for laboratory testing (2 inch sample tested) and the in place test was initiated. The CRVS booster fans {FAN} were found out of the allowable flow range (2000 cfm ± 10) and 1P2-CR-2007-00040 was written; actual flow was approximately 2500 cfm. Trouble shooting determined that high speed in the 21 Control Room Fan (CRF) associated with the air conditioner was the likely cause of the high airflow (the CRF and booster fans run in series). Sheaves were replaced on the 21 CRF (WR IP2-06-14505) lowering the CRF by about 500 cfm. This reduced the CRVS booster fan flow to allowable flow. Subsequent evaluation determined that the 21 CRF speed was adjusted on October 26, 2006 (WR-IP2-04-35618) without consideration of the effect on the CRVS booster fans. Post work tests were revised to verify flows on the CRVS booster fans following work that could affect flow on the 21 CRF.

A review of TS HVAC systems found no extent of condition. This was not determined to be reportable until January 31, 2007 during the review of charcoal sample test results (IP2-CR-2007-00130).

On January 10, 2007 the CRVS charcoal sample analysis came back as unacceptable (6.04 percent penetration with 5 percent allowable) and IP2-CR-2007-00130 was written. The sample was also tested at the face velocity associated with the as found fan condition of 2500 cfm and found unacceptable (10.11 percent penetration). The CR charcoal was replaced. The above testing was done for 2 inch samples as required by PT-EM-13, the bed design described in response to Generic Letter 99-02 in a letter dated September 11, 2000. The CRVS has two two-inch beds of charcoal. The charcoal was further laboratory tested for a 4 inch depth to demonstrate past operability. Using flow velocities of 2000 cfm and 2500 cfm, the tests showed penetrations of 0.67 percent and 1.07 percent, respectively. Based on this, the charcoal laboratory test results were determined to be not reportable.

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Cause of Event

The apparent cause is human performance weakness in the failure to foresee the effects of adjustments of the 21 CRF on the booster fans with respect to the resultant flow rates. A contributing cause was the lack of procedural guidance to require flow verification.

Corrective Actions

The following corrective actions have been or will be performed under Entergy's Corrective Action Program to address the cause and prevent recurrence:

• Briefed Program and Components Engineers and the Fan Component Engineer on the consequences of fan speed / flow changes.

• Revise maintenance and post work test procedures for the 21 CRF, the Control Room Circulating Fan (CRCF), and the CRVS booster fans to require verification of as found and as left fan RPMs, and to require airflow acceptance criteria to be met using 3PT-EM13 values for booster fans following all work. (CA 2 and 3 due May 2, 2007).

• The 21 CRF sheaves were changed to fixed rather than adjustable sheaves to maintain constant flow rates for the 21 CRF.

Event Analysis

This event is reportable under 10 CFR 50.73(a)(2)(i)(B), any event or condition that resulted in the nuclear power plant operating in a condition prohibited by TS. The January tests found the CRVS booster fans with flow values out of specification high. The evaluation determined that high booster fan flow rate was due to work on the 21 CRF on October 26, 2006. Fan speed was adjusted to meet TS on January 4, 2007. The plant was in non-compliance with TS 3.7.10 surveillance requirement for flow of 2000 cfm ± 10 percent for 71 days. There was no loss of safety function.

A review was conducted of Licensee Event Reports (LER) in the past two years for non-compliance with TS. 1P2 reported six events resulting in operations prohibited by Technical Specifications. LER­ 2005-001 reported an inoperable Component Cooling Water check valve that resulted in an inoperable Emergency Core Cooling train. LER 2005-002 reported an inoperable Safety Injection pump due to gas binding. LER 2006-002 reported two inoperable Post Accident monitors. LER 2006-007 reported pressure relief valves opened beyond allowable values. LER 2007-001 reported operation outside the allowed containment temperature value. LER 2007-002 reported an inoperable breaker for a residual heat removal pump. No common cause was identified.

Safety Significance

This event had no effect on the health and safety of the public. The CRVS was demonstrated to meet accident analysis acceptance criteria using flow velocities of 2500 cfm. The CRVS was fully capable of performing its function.