ML20029E799
| ML20029E799 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 05/11/1994 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20029E798 | List: |
| References | |
| NUDOCS 9405200180 | |
| Download: ML20029E799 (3) | |
Text
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2.
Single Unit Operation - One of the three operable auxiliary feedwater pumps associated with a unit may be out-of-service for the below specified times. The turbine driven auxiliary feedwater pump may be out-of-service for up to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
If the turbine driven auxiliary feedwater pump cannot be restored to service within that 72-hour time period, the reactor shall be in hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
Either one of the two motor driven auxiliary feedwater pumps may be out-of-service for up to 7 days.
If the motor driven auxiliary feedwater pump cannot be restored to service within that 7-day period the operating unit shall be in hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
D.
The main steam stop valves (MS-2017 and MS-2018) and the non-return check valves (MS-2017A and MS-2018A) shall be operable.
If one main steam stop valve or non-return check valve is inoperable but open, power operation may continue provided the inoperable valve is restored to operable status within 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />, otherwise the reactor shall be placed in a hot shutdown condition within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. With one or more main steam stop valves or non-return check valves inoperable, subsequent operation in the hot shutdown condition may proceed provided the inoperable valve or valves are maintained closed. An inoperable main steam stop valve or non-return check valve may however, be opened in the hot shutdown condition to cool down the affected unit and to perform testing to confirm operability.
E.
The crossover steam dump system shall be operabit..
If the crossover steam dump system is determined to be inoperable, reduce power to less than 480 MWe (gross) within 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br />.
F.
During power operation, at least one of the turbine overspeed protection systems that trip the turbine stop valves or shut the turbine governor valves shall be operable.
If all three systems are determined to be inoperable, isolate the turbine from the steam supply within the next six hours.
Unit 1 - Amendment No. M 3, 443, 147 Unit 2 - Amendment No. H7, 447, 151 Correction letter dated May 11, 1994 9405200100 940511 15.3.4-2a PDR ADOCK 05000266 p
G.
Should one of the turbine stop valves or governor valves be declared inoperable, restore the inoperable valve to an operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
If operability cannot' be restored, perform one of the following actions:
1.
Shut the affected valve within the next six hours.
2.
Isolate the turbine from the steam supply within the next six hours.
Basi.s A reactor shutdown from power requires removal of core decay heat.
Immediate decay heat removal requirements are normally satisfied by the steam bypass to the condenser. Therefore, core decay heat can be continuously dissipated via the steam bypass to the condenser as feedwater in the steam generator is converted to i
steam by heat absorption.
Normally, the capability to return feedwater flow to the steam generators is provided by operation of the turbine cycle feedwater system.
The eight main steam safety valves have a total combined rated capability of 6,664,000 lbs/hr.
The total full power steam flow is 6,620,or lbs/hr, therefore eight (8) main steam safety valves will be able to relieve the total full-power steam flow if neces sary.
In the unlikely evant of complete loss of electrical' power to the station, decay heat removal would continue to be assured for each unit by the availability of either the steam-driven auxiliary feedwater pump or one of the two motor-driven auxiliary steam generator feedwater pumps, and steam discharge to the atmosphere via the main steam safety valves or atmospheric relief valves. One motor-driven auxiliary feedwater pump can supply sufficient feedwater for removal of decay heat from a unit. The minimum amount of water in the condensate storage tanks ensures the ability to maintain each unit in a hot shutdown condition for at least one hour concurrent with a loss of all AC power.
An unlimited supply is available from the lake via either leg of the plant service water system for an indefinite time period.
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Unit 1 - Amendment No. 443, 147 Unit 2 - Amendment No. 447, 151 Correction letter dated May 11, 1994 15.3.4-2b
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Each of the AFW pumps possesses a low suction pressure trip that will protect it should a loss of feedwater occur. Additionally, should a steam generator tube rupture occur, the motor-operated steam admission valves for the turbine-driven AFW pumps serve as isolation boundaries for the affected steam generator.
The crossover steam dump system is designed to prevent the turbine from exceeding 132% of rated speed following a unit trip.
The system is armed at approximately 430 MWe. The system receivc: input from, and is actuated when the turbine auxiliary governor and/or the Independent Overspeed Protection System (IOPS) senses an overspeed condition. The system consists of four pilot-operated dump valves, with only three valves being necessary to achieve the required overspeed protection. However, in order to meet single failure criteria, the crossover steam dump system shall be declared inoperable if any one of the four dump valves is declared inoperable.
In addition to the crossover steam dump system, there are three other systems that protect the turbine from an overspeed condition.
The first feature is the mechanical overspeed trip mechanism which consists of an eccentric weight located in the turbine rotor extension shaft. The second feature uses the turbine auxiliary governor to sense turbine overspeed using the auxiliary speed tachometer.
The third feature is 10PS.
This system monitors turbine speed electrically and consists of three independent speed channels.
The actuation of two of three channels will generate a trip signal.
The mechanical overspeed trip mechanism and 10PS cause the turbine stop valves to trip and the turbine governor valves to shut, while the auxiliary governor causes only the governor valves to shut. A turbine stop valve shall be declared inoperable if it does not trip shut following a valid overspeed signal. A turbine governor valve shall be declared inoperable if it does not respond properly following a valid overspeed signal.
The atmospheric steam dump lines are required to be operable because they are relied upon, following a steam generator tube rupture coincident with a loss of A.C. power, to cool down the Reactor Coolant System to RHR entry conditions. An atmospheric steam dump line is considered operable if it is capable of providing the controlled relief of main steam flow necessary to perform the RCS cooldown.
Isolating an atmospheric steam dump line does not render it inoperable if the line can be unisolated and the RCS can still be cooled down to RHR entry conditions, through local or remote operation, within the time period required by the applicable FSAR accident analyses.
Unit 1 - Amendment No. 147 Unit 2 - Amendment No. 151 15.3.4-2c Correction letter dated May 11, 1994