05000250/LER-2014-004
| Turkey Point Unit 3 | |
| Event date: | 7-20-2014 |
|---|---|
| Report date: | 9-18-2014 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat |
| Initial Reporting | |
| ENS 50287 | 10 CFR 50.72(b)(3)(v)(B), Loss of Safety Function - Remove Residual Heat |
| 2502014004R00 - NRC Website | |
Reported lessons learned are incorporated into the licensing process and fed back to industry.
Send comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch(T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by intemet e-mail to Infocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
2. DOCKET
6. LER NUMER
DESCRIPTION OF THE EVENT
On July 20, 2014 at approximately 1454 hours0.0168 days <br />0.404 hours <br />0.0024 weeks <br />5.53247e-4 months <br />, with both Turkey Point Units 3 and 4 in Mode 1 and at 100% power, the Action for Technical Specification (TS) 3.7.4, Ultimate Heat Sink, was entered which requires both units to be placed in Hot Standby within 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and Cold Shutdown within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />.
The TS Action was entered because ultimate heat sink (UHS) [BS] temperature exceeded the TS limit of 100 degrees F. The TS Action was exited at approximately 2046 the same day when UHS temperature decreased below 100 degrees F. Units 3 and 4 were in the TS Action for a period of approximately 5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> and 52 minutes. Subsequently, on July 26, 27, 28 and August 7, 2014, both Turkey Point units entered and exited the Action for TS 3.7.4 once each day for periods of up to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> requirement to be in Hot Standby was not exceeded during these events and so there was no condition prohibited by the TS.
The events were reported to the NRC via Event Notification 50287 in accordance with 10 CFR 50.72(b)(3)(v)(B) because UHS capability to remove residual heat was impacted. This report is in accordance with 10 CFR 50.73(a)(2)(v)(B) for the same reason.
At 1800 hours0.0208 days <br />0.5 hours <br />0.00298 weeks <br />6.849e-4 months <br /> on July 20, 2014, the NRC granted enforcement discretion (NOED No. 14-2-001) to allow the Turkey Point units to continue operation with a UHS temperature of up to 103 degrees F provided certain compensatory measures were implemented and termination criteria were met. On August 8, 2014, the NRC issued License Amendments 261 and 256 for Turkey Point-Units 3 and 4, respectively, which raised the UHS temperature limit to 104 degrees F and terminated the need for enforcement discretion.
CAUSE OF THE EVENT
Environmental conditions outside of management control negatively impacted UHS water quality and the ability of the cooling canal system (CCS) to dissipate the heat rejected by plant operation.
A cause evaluation identified that existing monitoring activities should be enhanced-and integrated to improve the monitoring of CCS capability to accomodate normal and accident plant heat loads.
BACKGROUND INFORMATION
Turkey Point Units 1, 2, 3 and 4 use a closed system of cooling canals to support operation of the power plants. For nuclear units 3 and 4, the CCS provides the coolant for the Circulating Water (CW) [KE] system and the UHS for the Intake Cooling Water (ICW) [BS] system. The CW system provides cooling water to the main plant condensers. The ICW system removes heat loads from the Component Cooling Water [CC] system during normal and accident conditions to support both reactor [AC, RCT] and containment [NH] heat removal requirements, and spent fuel cooling [DA] requirements.
In June 2014, UHS temperatures approached the TS 3.7.4 limit of 100 degrees F. Engineering and environmental analysis determined that the CCS water was absorbing unusual amounts of solar energy due to APPROVED BY OMB: NO. 3150-0104 EXPIRES: 01/31/2017 Reported lessons learned are incorporated into the licensing process and fed back to industry.
Send comments regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by intemet e-mail to Infocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
the presence of higher than normal algae content. A controlled chemical treatment of the canal system was initiated to gradually restore the normal algae content and improve heat transfer efficiency, without adversely affecting plant and wildlife in the canal system.
On July 10, 2014, an application for license amendments to allow plant operation with UHS temperatures less than or equal to 104 degrees F was submitted for NRC review and approval.
ANALYSIS OF SAFETY SIGNIFICANCE
There was no increase in risk due to allowing the average water temperature of the UHS to increase from 100 degrees F to 103 degrees F during the period of enforcement discretion. The analysis performed for the license amendment application determined that an increase in UHS temperature to 104 degrees F had either no impact or an insignificant impact on the loss of coolant accident (LOCA) and non-LOCA results.
Additionally, component assessments were performed and determined that components served by the UHS would continue to perform satisfactorily with an increase in UHS temperature to 104 degrees F. No adverse influences on risk were identified through examination of the probabilistic risk analysis model for the plant.
Additionally, despite the hot weather conditions during the period of enforcement discretion (7/20/14 to 8/7/14), the average water temperature of the UHS exceeded the 100 degree F limit for only about 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> total.
CORRECTIVE ACTIONS
Corrective actions include:
- Increase in UHS temperature limit to 104 degrees F (Amendments 261 and 256 issued by the NRC on 8/8/14).
- Biocide treatment of the CCS water.
- Enhance and integrate existing monitoring activities to improve the monitoring of CCS capability to accomodate normal and accident plant heat loads.
ADDITIONAL INFORMATION
component function identifier (if appropriate)]. Condition Report 1979256 was initiated due to this event.
FAILED COMPONENTS IDENTIFIED: None.
PREVIOUS SIMILAR EVENTS: None.