05000315/LER-2002-004

LER-2002-004, Unit 1 Ice Condenser Lower Inlet Door Test Failure

Donald C. Cook Nuclear Plant Unit 1
Event date:
Report date:
3152002004R00 - NRC Website

05000-315 2002 004 00 17. TEXT (If more space is required, use additional copies of NRC Form (366A) Conditions Prior to Event Unit 1 - 0 percent power Unit 2 - 100 percent power

Description of Event

During performance of 12-MHP-4030-010-003, "Ice Condenser Lower Inlet Door Surveillance," Section 4.3, "Forty Degree Force Test," bay 15, door 15R (the right door), failed the opening force portion of the test. This test is performed to fulfill the surveillance testing requirements specified in Technical Specification (TS) 4.6.5.3.1.b.3.

The actual average opening force for door 15R was 7.458 pounds (lb). The established acceptance criteria for opening force is less than 6.625 lb. This door failed to meet the opening force requirement as specified in the surveillance procedure. This equates to an opening torque of 212.6 inch-pounds, in excess of the specified by TS.

The remaining TS surveillance requirements for the ice condenser doors were met.

Cause of Event

The Unit 1 ice condenser lower inlet doors were exempted from the requirement to perform the 40-degree force test surveillance as a result of Emergency License Amendment 265 for Unit 1, until this outage. During the performance of the 40-degree door test, which utilized the methodology developed during the Unit 2 refueling outage U2C13, door 15R exceeded the opening force criteria specified within the surveillance procedure.

An engineering evaluation concluded that this failure was directly attributable to the fact that during the extended shutdown, the door springs tension were set with the doors being held open with the previous 40 degree testing tool, which had been found to not position the door at the correct opening angle.

17. TEXT (if more space is required, use additional copies of NRC Form (366A)

Analysis of Event

The Unit 1 Ice Condenser System, including the ice condenser doors, was refurbished prior to the previous operating cycle. For the identified condition, the potential impact of the failure of ice condenser door 15R was a failure to meet TS requirements. Given an assumed failure of both ice condenser doors in a specific bay to meet the 40-degree test opening force requirements, the ice condenser remained available to perform its design function. Analytical results have demonstrated that several ice condenser doors could fully fail to open upon demand without impacting the function of the ice condenser. As such, the Unit 1 ice condenser remained OPERABLE. Therefore, this event would not have adversely impacted the plant's ability to mitigate the consequences of an accident and therefore had minimal safety significance.

Corrective Actions

The springs for ice condenser door 15R were adjusted and the door was successfully retested in accordance with the requirements of TS 4.6.5.3.1.b.3.

Previous Similar Events

Michigan Power (I&M), to establish operability of the ice condenser doors was flawed.

Based on this discovery, I&M, was granted a one time exemption from the testing requirements of TS 4.6.5.3.1.b.3 until the unit entered an outage of sufficient duration that would facilitate the testing of the doors. Upon testing of the doors I&M identified that door 15R was incorrectly adjusted. Therefore the corrective actions established in LER 50-315/2002-001-00 could not have prevented the condition that is documented in this LER.