05000272/LER-2009-001
| Docket Number Sequential Revmonth Day Year Year Month Day Yearnumber No. | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2722009001R01 - NRC Website | |
PLANT AND SYSTEM IDENTIFICATION
Westinghouse — Pressurized Water Reactor (PWR/4) Chilled Water System {KM/TS} * Energy Industry Identification System {ElIS} codes and component function identifier codes.app_ear as {SS/CCC}
IDENTIFICATION OF OCCURRENCE
Event Date: December 5, 2009 Discovery Date: December 7, 2009�
CI
CONDITIONS PRIOR TO OCCURRENCE
Salem Unit 1 was in Operational Mode 1 at 100% reactor power
DESCRIPTION OF OCCURRENCE
On 11/29/09 at 1345 hours0.0156 days <br />0.374 hours <br />0.00222 weeks <br />5.117725e-4 months <br />, 12 Chiller was removed from service (a 14-day Limiting:Condition for Operation (LCO) entered) for maintenance and design change installation. All appropriate non-essential heat loads were removed from the chilled water system {KM/-} as required by Technical Specifications (TS) 3.7.10 "Chilled Water System — Auxiliary Building Subsystem." The 12 Chiller,had been operating properly prior to its removal from service.
On 12/02/09 at 1713 hours0.0198 days <br />0.476 hours <br />0.00283 weeks <br />6.517965e-4 months <br /> the 13 Chiller was found out of service and declared inoperable: With two (2) Chillers (i.e., 12 and 13) inoperable, a 72-hour LCO was entered in accordance with TB 3.7:10 Action b.3, expiring on 12/05/09 at 1713 hours0.0198 days <br />0.476 hours <br />0.00283 weeks <br />6.517965e-4 months <br />.
On 12/04/09 the 12 Chiller tripped on freeze protection shortly after being placed in service for testing.
The trip was due to the low temperature cutout. The trip was reset, and the 12,Chiller re-started,.but tripped again after a short run. The recently performed Chiller work scope was,,reviewed;.the only work items that could have affected Chiller operation were the liquid line solenoid valve (LLSV) addition and the Chiller internal inspection (unloader adjustment). The LLSV was verified td:be operating correctly by temperature measurements across the valve. The unloader was adjusted and the 12 Chiller was declared Operable at 2017 hours0.0233 days <br />0.56 hours <br />0.00333 weeks <br />7.674685e-4 months <br /> and the 72-hour LCO exited. However, the original 14-day LCO window remained active because of the inoperability of 13 Chiller.
DESCRIPTION OF OCCURRENCE (cont'd) On 12/07/09, during the operability retest of 13 Chiller, 12 Chiller tripped on low temperature freeze protection. The 72-hour LCO was re-entered at 0907 hours0.0105 days <br />0.252 hours <br />0.0015 weeks <br />3.451135e-4 months <br />, with an expirationdate of 12/10/09 at 0907 hours0.0105 days <br />0.252 hours <br />0.0015 weeks <br />3.451135e-4 months <br />. A detailed troubleshooting of the 12 Chiller was performed which included a calibration check of the low temperature trip switch. This switch was found to be out of calibration,,tripping 7 degrees F above its setpoint. The setpoint for the freeze trip from this device is 35 +/- 1.5 degrees F. The 12 Chiller low temperature trip switch was promptly reset to correct the setpoint. However, the 12 Chiller was not declared Operable due to other equipment issues.
On 12/07/09 at 1126 hours0.013 days <br />0.313 hours <br />0.00186 weeks <br />4.28443e-4 months <br />, 13 Chiller was declared Operable and the 72-hour LCO exited.
However, because the low temperature trip switch setting that made the 12 Chiller inoperable existed during the period 12/02/09 through 12/07/09 while 13 Chiller was inoperable, two Chillers were inoperable for longer than the 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> allowed by TS 3.7.10 Action b.3.
This report is being made in accordance with 10CFR50.73 (a)(2)(i)(B), "any operation ... prohibited by the plant's Technical Specification.
CAUSE OF OCCURRENCE
The cause of the 12 Chiller tripping on freeze protection was the low temperature trip switch being set 7 degrees F high. The low temperature trip switch was found out of position from where it was left following calibration in June 2009. The cause for the mispositioned setpoint knob is unknown but most likely occurred during the 11/29/09 maintenance and design change installation window.
PREVIOUS OCCURRENCES
A review of LERs for Salem Station back to 2006 identified one previous similar occurrence, LER 311/07-001-00, "Inoperability of the Chilled Water System - 21 and 22 Chillers Inoperable. The cause of this LER was a loose key switch barrel in its mounting hole that allowed the body of the switch to rotate and provide a false indication of Chiller operating status. The corrective actions associated with LER were specific to that event and would not have prevented this LER.
SAFETY CONSEQUENCES AND IMPLICATIONS
There was no actual safety consequences associated with this event.
Although the opposite unit Control Room Emergency Air Conditioning System (CREACS) was not placed in single train filtration in accordance with TS for having two inoperable Chillers, the ability of the system to perform its safety function was not compromised. Placing the opposite units' CREACS in single train filtration means that the airflow through the affected unit is being circulated with the opposite units' fans to minimize the heat load in the affected unit.
SAFETY CONSEQUENCES AND IMPLICATIONS (cont'd) At the time of the event, appropriate non-essential heat loads had been removed from service because the original inoperability of the 12 Chiller on 11/29/09. Furthermore, the environmental condition (river water temperature was 55 degrees F) at the beginning of December was not near the 90 degrees F assumed in the accident analysis. Therefore, the significance of not having placed the CREACS in single train filtration was minimal.� , A review of this event determined that a Safety System Functional Failure (SSFF) as defined in NEI 99- 02, Regulatory Assessment Performance Indicator Guidelines, did not occur. There was no condition that alone, could have prevented the fulfillment of a safety function of a system needed to remove residual heat.
CORRECTIVE ACTIONS
1. The trip setpoint for the low temperature cutout (freeze) trip on 12 Chiller was re-adjusted to the correct setpoint of 35 +1- 1.5 degrees F.
2. Review of work orders and notifications written between May and December 2009 was completed and did not identify any activities that may have required work in the 12 Chiller control panel.
3. A cause evaluation is in progress, any additional corrective actions associated with this event will be tracked in the PSEG Corrective Action Program.
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COMMITMENTS
No commitments are made in this LER. I.
s.