05000382/LER-2008-002

LER-2008-002, Inoperable Steam Generator Narrow Range Level Channels

Docket Number
Event date:	05-23-2008
Report date:	07-17-2008
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
3822008002R00 - NRC Website

REPORTABLE OCCURRENCE

On May 23, 2008, one transmitter for SG 1 and one transmitter for SG 2 used for narrow range level PPS trip input were determined to be inoperable. The transmitters were out of calibration and inoperable during Cycle 15. Technical Specification Table 3.3-1, Action 2, requires that with the number of channels operable one less than the total number of channels, which are four per Steam Generator, startup or power operation may continue provided the inoperable channel is placed in the bypassed or tripped condition within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />. Plant personnel were unaware of this condition during Cycle 15, and therefore did not place the inoperable channels in the bypass or tripped condition per the Technical Specification. This condition constituted a violation of Technical Specification Table 3.3-1, and the condition is reportable within 60 days pursuant to 10CFR 50.73(a)(2)(i)(B).

INITIAL CONDITIONS

At the time the two SG level transmitters were determined to be inoperable, the plant was in Mode 6 , refueling. There were no other structures, systems, or components inoperable at the time of discovery that contributed to this condition.

EVENT DESCRIPTION

On May 8, 2008, maintenance was being performed per procedures MI-003-005 and MI-003-006, Steam Generator Level Loop Check and Calibration for SG 1 and SG 2 respectively. During the performance of the maintenance, personnel discovered that one transmitter for SG 1 and one transmitter for SG 2 used for SG narrow range level PPS trip input were out of calibration. On May 23, 2008, evaluation established the two transmitters were inoperable during Cycle 15 operation.

CAUSAL FACTORS

During RF14 seven of the eight SG level transmitters used for PPS trip input were replaced for SG 1 and SG 2. The transmitters were replaced by temporary outage workers. The one SG narrow range transmitter that was not replaced remained in calibration during Cycle 15 operation. The Apparent Cause Evaluation established the condition occurred due to procedural inadequacy as the procedures did not provide sufficient detail to assure proper manipulations of valves and venting of sensing lines after installation of the seven SG narrow range transmitters.

CORRECTIVE ACTIONS

Corrective actions taken include:

■ An Apparent Cause Evaluation, documented in condition report CR-WF3-2008-2107, was performed.

■ A Failure Modes and Effects Evaluation was performed.

■ The seven SG narrow range transmitters were calibrated.

■ A Corrective Action Program (CAP) action was issued to revise calibration procedures.

■ A CAP action was issued to enhance the training for temporary outage workers in the calibration of transmitters.

SAFETY SIGNIFICANCE

The condition described in this LER has minimal safety significance.

The SG narrow range level transmitters provide inputs to the PPS safety channels to actuate two PPS functions: (1) initiate reactor trip on SG high level and (2) initiate reactor trip and Emergency Feedwater Actuation Signal (EFAS) on low SG level. Evaluation of the safety analysis and setpoints established that the PPS analytical limit for EFAS on low SG level could not have been exceeded based on the degree of the out of calibration of the transmitters. The evaluation established the analytical limit for the PPS limit for high SG level could have been exceeded based on the magnitude of the out of calibration condition. The SG high level PPS trip is an equipment protection trip and not a safety function trip. The SG high level PPS trip prevents excessive moisture carryover from the steam generator [SB] from reaching the turbine [TA], which could result in damage to the turbine. Three of the,four SG narrow range channels were available and operable during Cycle 15 operation. Two SG narrow range channels are required to generate a reactor trip.

There was a zero percent delta Core Damage Frequency, or no increase in core damage probability, with j both transmitters not operable. This condition did not exceed the NRC Green criteria of

SIMILAR EVENTS

A record search was performed for other similar reported conditions at Waterford 3. No similar conditions were identified and reported over the last 3 year period.

ADDITIONAL INFORMATION

Energy industry identification system (EllS) codes are identified in the text within brackets [ ].