05000456/LER-2006-002

LER-2006-002, Units 1 and 2 Entry into Limiting Condition for Operation 3.0.3 due to Main Control Room Ventilation Envelope Low Pressure

Docket Number
Event date:	10-04-2006
Report date:	12-04-2006
Initial Reporting
4562006002R00 - NRC Website

Plant Operating Conditions Before The Event:

Event Date: October 4, 2006 Event Time: 0247 Unit: 1 MODE: 1 Reactor Power: 100 percent Unit: 2 MODE: 1 Reactor Power: 87 percent Unit 1 Reactor Coolant System (RCS) [AB] Temperature: 587 degrees F. Pressure: 2233 psig Unit 2 Reactor Coolant System (RCS) [AB] Temperature: 575 degrees F. Pressure: 2241 psig . Description of Event:

There were no additional structures, systems or components inoperable at the beginning of the event that contributed to the severity of the event.

On October 3, 2006, at 0730, Maintenance began a load test of a new constant voltage transformer (CVT). The testing continued into October 4, 2006. Two electricians that were assigned to complete the CVT test were alternating responsibilities of taking test readings on the CVT every 30 minutes.

On October 4, 2006, The first electrician (EMD1) was in the testing area between 0030 and 0130. During this time, EMD1 noted the increase of heat in the room. Several times during EMD1's duties, he opened the door between the Division 21 Miscellaneous Equipment Electric Room and the Train B Control Room Ventilation Room [VI], standing in the archway to cool himself, and then closed the door. The door was held open for no more than three minutes. At approximately 0130, a second electrician (EMD2) relieved EMD1. EMD2 placed a roll of tape between the door and the door casing to allow cooler outside air to enter the room.

At 0138, the Main Control Room (MCR) received an annunciator alarm for MCR low pressure. Operations entered the applicable alarm response and instructed a Non-licensed Operator (NLO) to adjust Auxiliary Building pressure.

At 0220, an NLO adjusted pressure in the Auxiliary Building, raising it above the minimum required value.

Operations personnel continued to investigate the reason for the MCR annunciator alarm.

At 0247, Operations personnel reported to the MCR that the door that connects Division 21 Miscellaneous Equipment Electric Room and the Train B Control Room Ventilation Room was found open. Operations personnel promptly shut the door and the MCR low pressure annunciator cleared.

A late log entry was made to enter Technical Specification (TS) 3.7.10 conditions A & E and TS 3.0.3 for both units at the point of discovery of the door being found open, which was at 0247. The LCOs were subsequently exited immediately after the door was closed at 0247. This did not result in a dual unit shutdown.

This information is being transmitted to the NRC as a voluntary Licensee Event Report to report a condition that may be of potential generic interest for licensees and to describe the fact that the station entered TS Limiting Condition for Operation (LCO) 3.0.3 for the aforementioned condition. NUREG 1022 (Revision 2) states: TS LC(} 3.0.3 establishes requirements for actions when: (1) an LCO is not met and the associated ACTIONS are not met; (2) an associated ACTION is not provided, or (3) as directed by the associated ACTIONS themselves. Entry into TS LCO 3.0.3 is not necessarily reportable under this criterion. However, it should be considered reportable under this criterion if the condition is not corrected within an hour, such that it is necessary to initiate actions to shutdown, cool down, etc.

Entry into TS LCO 3.0.3 did not result in a reportable condition because it was not necessary to initiate actions to shutdown within one hour as Operations personnel were fully aware of the MCR low pressure annunciator and were taking the appropriate action to identify the cause of the alarm condition. Had the duration of the investigation by Operations exceeded the allowed outage time established in TS LCO 3.0.3, this event would have been reportable under 50.73(a)(2)(i)(B), "Operation or Condition Prohibited by Technical Specifications.

Cause of Event

The cause of the event was due to an electrician (EMD2) improperly propping open the door between the Division 21 Miscellaneous Equipment Electric Room and the Train B Control Room Ventilation Room.

To conduct the test of the new CVT, a resistive load bank is wired to the CVT to simulate an electrical load. As with all resistive loads, this bank produced a great deal of heat, which began to affect ambient temperatures inside the room. The closest door to the work site connects the Division 21 Miscellaneous Equipment Electric Room and the OB Control Room Ventilation Room. EMD2 placed a roll of tape between the door and the door casing to allow cooler outside air to enter the room.

On the door is signage that states "DO NOT IMPAIR this HVAC Boundary before referring to PBI procedure BwAP 1110-3.

This signage was not noticed by EMD2 because of his positioning at the work location. During the investigative interviews, EMD2 stated he did not recognize the sign on the door; therefore he felt propping open the door was not wrong because he was in attendance. This decision was not discussed with the EM Supervisor or with Operations.

This was an improper decision, as there are very few doors that are allowed to be propped open in the plant. It is an expectation for all employees to question procedural compliance before propping any door.

Safety Consequences:

There were no safety consequences impacting plant or public safety as a result of this event. Actions taken in response to the annunciator alarm for low pressure restored the pressure differential in the Auxiliary Building. The opened door was located and closed. For the duration of the event (70 minutes), the MCR pressure remained positive.

This event did not result in a safety system functional failure.

Corrective Actions:

Corrective actions in response to this issue included coaching and counseling of the individuals involved in the issue, initiating a Training Review to evaluate adding FBI criteria to 2007 annual training for all maintenance departments, and holding a station-wide stand down to communicate human performance errors recently encountered at the station.

Previous Occurrences:

There have been no previous similar events at Braidwood Station.

Component Failure Data:

Manufacturer � Nomenclature � Model � Mfg. Part Number N/A � N/A � N/A � N/A