ML092580382
| ML092580382 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 09/04/2009 |
| From: | Jordan A Dominion Nuclear Connecticut |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| FOIA/PA-2011-0115 | |
| Download: ML092580382 (5) | |
Text
Dominion Nuclear Connecticut, Inc.
Millstone Power Station Dominion Rope Ferry Road Waterford, CT 06385 SEP 0 4 2009 U.S. Nuclear Regulatory Commission Serial No.09-537 Attention: Document Control Desk NSSL/MLC RO Washington, DC 20555 Docket No. 50-423 License No. NPF-49 DOMINION NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNIT 3 30-DAY SPECIAL REPORT FOR AREA TEMPERATURE MONITORING -
CONTAINMENT AREA CS-03 (PRESSURIZER CUBICLE)
Dominion Nuclear Connecticut, Inc. (DNC) hereby forwards a special report in accordance with Millstone Power Station Unit 3 (MPS3) Technical Specifications (TSs) 3.7.14.b and 6.9.2 to document conditions surrounding temperature monitoring in the pressurizer cubicle area.
MPS3 TS 3.7.14.b requires a special report be submitted to the Nuclear Regulatory Commission (NRC) within 30 days of exceeding a specified area temperature limit by less than 20°F and for a duration of greater than or equal to eight hours. The report for the pressurizer cubicle temperature area is contained in Attachment 1.
If you have any questions regarding this submittal, please contact Mr. William D. Bartron at (860) 444-4301.
Sincerely, A. J. dan Site Vice President - Millstone
Attachment:
1
- 1. Special Report for Area Temperature Monitoring - Containment Area CS Pressurizer Cubicle, Elevation All Commitments made in this letter: None
Serial No.09-537 30-Day Special Report Docket No. 50-423 Page 2 of 2 cc: U.S. Nuclear Regulatory Commission Region I 475 Allendale Road King of Prussia, PA 19406-1415 Ms. C. J. Sanders Project Manager - Millstone Power Station U.S. Nuclear Regulatory Commission One White Flint North 11555 Rockville Pike Mail Stop O-8B3 Rockville, MD 20852-2738 NRC Senior Resident Inspector (w/o attachments)
Millstone Power Station,
Serial No.09-537 Docket No. 50-423 ATTACHMENT I 30-DAY SPECIAL REPORT FOR AREA TEMPERATURE MONITORING CONTAINMENT AREA CS PRESSURIZER CUBICLE, ELEVATION ALL DOMINION NUCLEAR CONNECTICUT, INC.
MILLSTONE POWER STATION UNIT 3
Serial No.09-537 30-Day Special Report Docket No. 50-423 Attachment 1 Page 1 of 2 30-DAY SPECIAL REPORT FOR AREA TEMPERATURE MONITORING CONTAINMENT AREA CS PRESSURIZER CUBICLE, ELEVATION ALL This special report is being submitted pursuant to Millstone Power Station Unit 3 (MPS3)
Technical Specification (TS) 3.7.14, "Plant Systems: Area Temperature Monitoring." TS 3.7.14.b requires that a special report be submitted within 30 days, if one or more area(s) exceeds the temperature limits specified in Table 3.7-6, by less than 20°F and for a period of greater than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. This report provides the cumulative time and the amount by which the temperature in the reactor coolant system pressurizer cubicle (CS-03) exceeded the limits and describes an analysis that demonstrates the continued operability of the affected equipment.
Area CS-03 is monitored by temperature element 3ECS-TE137.
On August 9, 2009 at 0852 hours0.00986 days <br />0.237 hours <br />0.00141 weeks <br />3.24186e-4 months <br />, with the plant in Mode 1 at 100% power, 2259 psia and 586 0 F, temperature element 3ECS-TE137 measured the ambient temperature inside area CS-03 to be greater than 1300 F. At 0852 hours0.00986 days <br />0.237 hours <br />0.00141 weeks <br />3.24186e-4 months <br /> on August 10, 2009, 3ECS-TE137 indicated that the temperature inside the pressurizer cubicle went below 130 0 F. The total time of the temperature excursion was approximately 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, with a maximum temperature of 130.80 F during the temperature excursion. Temperature element 3ECS-TE137 was monitored and verified less than 150°F - the temperature at which equipment in the area monitored by 3ECS-TE137 must be declared inoperable in accordance with TS 3.7.14.c.
A containment walkdown previously performed on May 7, 2009, validated the indication of the temperature element and operation of the ventilation system. No leakage was seen affecting area temperature conditions. The temperature excursion is originating from normal operating temperature influences on the pressurizer cubicle.
The area CS-03 temperature element, 3ECS-TE137, is located at elevation 87'-0" and is 11' above the highest safety-related Environmentally Qualified (EQ) component. The readings at this elevation reflect the worst-case ambient air temperature in the cubicle. Because the temperature element is so far above affected components, it is exposed to much higher temperatures than the ambient air conditions in the vicinity of the EQ components. The following table identifies EQ components for pressurizer cubicle (CS-03) and their elevations.
Description Component ID Elevation Analysis Actual Temp Temp Power-Operated Relief 3RCS*MV8000A/L 55'-4" 147 0 F 103 0 F Valve Block Valves 3RCS*MV8000B/L 55'-4" 147 0 F 103 0 F Power-Operated Relief 3RCS*PCV455A 76'-0" 121 OF 113 0 F Valves 3RCS*PCV456 75'-0" 121°F 113 0 F 3RCS*SV8095A 56'-0" 1 14.8 00 F 103 00 F Reactor Vessel Head 3RCS*SV8095B 53'-0" 114.8 F 103 F Vent Valves 3RCS*SV8096A 56'-0" 1 14.8 0 F 103 0 F 3RCS*SV8096B 53'-0" 1 14.8 0F 103 0 F 3RCS-FE48A 70'-0" 246°F 1 13°F Pressurizer Safety Valve 3RCS-FE48A 70'-0" 246 0 F 113 0F Position Indication 3RCS-FE48B 70'-0" 2460F 113 0 F 3RCS-FE48C 70'-0" 246°F 113°F
Serial No.09-537 30-Day Special Report Docket No. 50-423 Attachment 1 Page 2 of 2 The "Analysis Temp" identified above represents the ambient temperature used in the thermal life analysis. The analysis considers components at this temperature constantly throughout their 40-year lives. The "Actual Temp" represents an approximation of the ambient temperatures in the vicinity of the EQ components based on their actual elevations. The data shown above was obtained during the May 7, 2009 walkdown. The actual component ambient temperatures are below the analysis temperatures such that component thermal life qualifications are not impacted by the alarming condition of 3ECS-TE1 37. Hence, the area ambient temperatures in the vicinity of the affected EQ components do not present a challenge to current operability.
Walkdown data has determined that a temperature gradient has been demonstrated in the MPS3 pressurizer cubicle (CS-03). When 3ECS-TE137 (87' elevation) is at 128 0 F, walkdown data identified an ambient air temperature of 11 3°F (80' elevation) and 103°F (72' elevation).
The 80' elevation ambient air temperature was conservatively selected to represent the environmentally qualified component values. Component locations are a minimum of 4' below this elevation such that actual component ambient air temperatures would be slightly less.
Since the ambient air temperature, used in the service-life analysis, is 121'F, there is a margin of 8 0 F between the actual measured air temperature and the value used in the analysis when 3ECS-TE137 reads approximately 128°F. Therefore, when 3ECS-TE137 reads 136 0 F (87' elevation) a corresponding temperature of 121 OF is assumed at the highest elevation for the environmentally qualified components. Hence, service life analysis is considered to remain bounded up to and including pressurizer cubicle ambient air temperatures of 136 0 F as read on 3ECS-TE137.
Since the time of the initial reportable interval discussed above, pressurizer cubicle temperature (i.e., CS-03) has been fluctuating around the 130°F limit for periods of sometimes greater than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> and with a maximum recorded reading of 131.1°F. Because of this condition, the unit has remained in the action for TS 3.7.14 and is continuing to monitor pressurizer cubicle temperature through the current operating cycle.
During the period of time the unit remains in the condition where pressurizer cubicle temperature is greater than 130'F but less than 136 0 F for a duration of greater than 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, it is concluded the thermal life qualifications are not impacted and there is no challenge to continued equipment operability for those intervals. If plant conditions change such that pressurizer cubicle temperatures increase above those described above, DNC will submit additional correspondence.
Further investigation and corrective actions are planned to correct this condition.