ML20005A004
| ML20005A004 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 06/26/1981 |
| From: | Vincent R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| TASK-15-15, TASK-RR NUDOCS 8106290241 | |
| Download: ML20005A004 (7) | |
Text
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o General Offices: 212 West Michleen Avenue Jackson, MI 49201'e (517) 788-0550 June 26, 1981 Director, Nuclear Reactor Regulatien Att Mr Dennis M Crutchfield, Chief Operating Reactors Branch No 5 US Nuclear Regulatory Comissicu Washington, DC 20555 DOCKET 50-155 - LICENSE DPR BIG ROCK POINT PLANT - SEP TOPIC XV-15, INADVERTENT OPTTING OF A PWR PRESSURIZER SAFETY / RELIEF VALVE OR A BWR SAFETY / RELIEF VALVE Attached is the Consu=ers Pcver Co=pany evaluation of SIP Topic XV-15 for the Big Rock Point Plant.
Robert A Vincent (Signed)
Robert A Vincent Staff Licensing Engineer CC Director, Regien III, USIGC IGC Resident Inspector - Big Rock Point r
a't 8106290
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Topic IX-15: Inadvertent Opening of a PWR Pressurizer Safety / Relief Valve or a BWR Safety / Relief Valve Evaluation:
Big Rock Point utilizea mechanically operated safety valves for reactor system overpressure protection. The six safety valves are mounted on the top of the steam drum and set to relieveatpressuresbetween1550and1660gsia. Each safety value has an effective flow area of.028 ft and cannot be isolated. Nomal reactor system operating pressure is 1350 psia, and the emergency condenser is automatically actuated at 1450 psia. If at least one of the two e=ergency condenser tube bundles is placed in service, analyses (based on actual plant perfomance testing of the emergency condenser) shows that the lowest relief valve setpoint will not be reached for any anticipated transients.
Big Rock Point also utilizes solenoid operated relief valves as part of its emergency core cooling system. These valves comprise the reactor depressurization system (RDS) and are automatically opened on coincident signals of low steam drum level, low reactor water level, and high fire header pressure to blowdown the reactor coolant system and thereby permit injection of low pressure core spray water. In addition, each RDS valve may be manually operated from the control room, and an air operated isolation valve is provided upstream of each RDS valve to pemit manual isolation of the blevdown path. Each RDS valve and its associated blevdown path has an effecti e flow area of 0.05 ft2, Inadvertent operation of a reactor coolant system ssfety or RDS valve is considered a loss of coolant accident. Following opening of the valve the initial pressure regulator vill act to reduce steam flow to the turbine and thereby maintain pres-sure relatively constant until the reactor trips on high con-tainment pressure. As BRP has no high pressure makeup system, other than main feedvater, capable of maintaining system inven-tory with a stuck open safety or RDS valve, water level vill eventually fall to the RDS actuation setpoint and thereafter core cooling vill be provided by core spray.
(Note that the feedvater system would only be espable of provii.ing sufficient makeup for a short period of time - less than 15 minutes before the condensate pumps trip on low condenser hot vell level.)
2 The 0.05 ft steam line break (equivalent to a stuck opua PDS valve)l) was analyzed using the General Electric SAFE computer code.l The methods used in this analysis have been approved by the NRC staff as being in compliance with 10CFR50 Appendix K. '
The results of this analysis are shown on Figures 1 h.
Less than one foot of reactor fuel (trace 2 on Figure 2) beco=ec uncovered during the event. Therefore na fuel heatup or fuel failure vould be expected to occur and offsite dose consequences would be negligible.
It is therefore concluded that BRP com,
plies with current staff criteria (.SRP 15.6.1) for this event.
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Re ferences (1) " Big Rock Point Plant: Ioss-of-Coolant Accident Analysis for General Electric Fuel in Conformance with 10CFR50
- Appendix.K (Non-jet Pump Boiling Water Reactor)", July 11, 1975.. This report was Appendix A of the' July 25,-1975 submittal from Consumers Power Co. to the NRC, Docket 50-155, License DPR-6
'(2) Safety Evaluation by the Office of Nuclear Reactor Regu-lation Supporting Armendment No.10 to Facility License No. DPR-6, Consumers Power Company Big Rock Point Plant Docket No. 50-155, June 4, 1976.
FIGURE 1 BIG ROCK PT STEAM LINE f
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FIGURE 3 BIG ROCK PT d2 STEAM LINE W"
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. FIcuar b BIG ROCK PT
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