ML20091Q477
| ML20091Q477 | |
| Person / Time | |
|---|---|
| Site: | Point Beach  |
| Issue date: | 06/07/1984 |
| From: | WISCONSIN ELECTRIC POWER CO. |
| To: | |
| Shared Package | |
| ML20091Q462 | List: |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737 TAC-54559, TAC-54560, NUDOCS 8406140043 | |
| Download: ML20091Q477 (6) | |
Text
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i 5.
Pressurizer Power-Operated Relief Valves (PORV) and PORV Block Valves a.
Two PORVs and their associated block valves shall be operable.
(1) If a PORV is inoperable due to leakage in excess.of that allowed in Specification 15.3.1.D. the PORV shall be restored to an operable condition within one hour or the associated block valve shall be closed.
(2) If a PORV is inoperable due to a channel functional test failure, the associated PORV control switch shall be placed and maintained in the closed position or the associated block valve shall be closed within one hour.
(3) If a PORV block valve is inoperable, the block valve shall be restored to an operable condition within one hour or the block valve shall be closed with power removed from the block valve; otherwise the unit shall be in hot shutdewn within the next six hours.
6.
The pressurizer shall.be operable with at least 100 KW of pressurizer heaters available and a water level greater than 10% and less than 95%
during steady-state power operation. At least one bank of pressurizer heaters shall be supplied by an emergency bus power supply.
7.
Reactor Coolant Gas Vent System These Specifications are not applicable during cold or refueling shutdown conditions:
a.
At least one Reactor Coolant Gas Vent System vent path to the pressurizer relief tank (PRT) or containment atmosphere shall be operable from each of the following locations:
(1) Reactor vessel head (2) Pressurizer Each vent path from these locations to the common header includes two closed valves in parallel powered from emergency buses. The common header vents to the PRT and the containment atmosphere each contain a closed valve powered from an emergency bus which provides series isolation.
b.
When unable to vent from the. common header to the PRT or the containment atmosphere, reactor startup and/or power operations may continue provided that the series isolation valve in the inoperable vent path is maintained closed with power removed from the valve _ actuator.
8406140043 840607 PDR ADOCK 05000266
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15.3.1-3 PDR p
reactor heat equivalent to 10% of rated power can be removed with natural circula-tion only; hence, the specified upper limit of 1% rated power without operating pumps provides a substantial safety factor.
Item,14.3.1.A.1.C(2) permits an orderly reduction in power if a Reactor Coolant Pump is lost during operation between 10% and 50% of rated power.
Above 50% power, an automatic reactor trip will occur if either pump is lost.
The power-to-flow ratio will be maintained equal to or less than 1.0, which ensures that the minimum DNB ratio increases at lower flow since the maximum increase above its normal full-flow maximum value.( }
enthalpy rise does not Specification 15.3.1.A.3 provides limiting conditions for operation to ensure that redundancy in decay heat removal methods is provided. A single Reactor Coolant loop with its associated steam generator and a Reactor Coolant Pump or a single residual heat removal loop provide sufficient heat removal capacity for removing the reactor core decay heat; however, single failure considerations require that at least two decay heat removal methods be available.
Operability of a steam generator for decay heat removal includes two sources of water, water level indication in the steam generator, a vent path to atmosphere, and the Reactor Coolant System filled and vented so thermal convection cooling of the core is possible.
If the steam generators are not available for decay heat removal, this Specification requires both residual heat removal loops to be operable unless the reactor system is in the refueling shutdown condition with the refueling cavity flooded and no operations in progress which could cause an increase in reactor decay heat loa or a decrease in boron concentration.
In this condition, the reactor vessel is essentially a fuel storage pool and removing a RHR loop from service provides conservativc conditions should operability problems develop in the other RHR loop.
Also, one residual heat removal loop may be temporarily out of service due to surveillance testing, calibration, or inspection requirements. The surveilt.ance procedures follow administrative controls which allow for timely restoration of the residual heat removal loop to service if required.
Each of the pressurizer safety valves is designed to relieve 288,000 lbs. per hour of saturated steam at setpoint.
If no residual heat is removed by any of 15.3.1-3b
91 c.
If a vent path from the reactor vessel head or the pressurizer to the common header becomes inoperable, reactor startup and/or power operations may continue provided that the paralleled isolation valves in the inoperable vent path from that location to the common header are maintained closed with power removeC from the valve actu-ator. This does not necessitate removing powe-from the PRT or containment atmosphere isolatien valves. The inoperable vent path shall be restored to operable statur within thirty days, or the reactor shall be placed in hot shutdown within six hours and in cold shutdown within the following thirty hours, d.
If the vent paths from both the reactor vessel head and the pressur-izer to the common header are inoperable or the vent paths from the common header to both the PRT and the containment atmosphere are in-operable, then maintain all the inoperable vent path valve closed with power removed from the valve actuators of all the valves in the inoperable vent paths. Restore at Icast one of the vent paths from the reactor vessel head or pressurizer to the containment at-mosphere or the PRT to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> or be in hot shutdown within six hours and in cold shutdown within the following thirty hours.
Basis When the boron concentration of the Reactor Coolant System is to be reduced, the process must be uniform to prevent sudden reactivity changes in the Reactor.
Mixing of the Reactor Coolant will be sufficient to maintain a uniform boron concentration if at least one Reactor Coolant Pump or one residual heat removal pump is running while the change is taking place. The residual heat removal pump will circulate the primary system volume in approximately one-half hour. The pressurizer is of little concern because of the lower pressurizer volume and because pressurizer boron concentration normally will be higher than that of the rest of Reactor Coolant.
Specification 15.3.1.A.1 requires that a uufficient number of Reactor Coolant Pumps be operable to provide core cooling in the event a loss of power occurs.
The flow provided in each case will keep DNBR well above 1.30 as discussed in FSAR, Section 14.1.9.
Therefore, cladding damage and release of fission products to the reactor coolant will not occur. Heat transfer analyses } show that 15.3.1-3a
f I.
I reactor heat equivalent to 10% of rated power can be removed with natural circula-tion only; hence, the specified upper limit of 1% rated power without operating pumps provides a substantial safety factor.
Item 14.3.1.A.1.C(2) permits an orderly reduction in power if a Reactor Coolant Pump is lost during operation between 10% and 50% of rated power.
Above 50% power, an automatic reactor trip will occur if either pump is lost.
The power-to-flow ratio will be maintained equal to or less than 1.0, which ensures that the minimum DNB ratio increases at lower flow since the maximum enthalpy rise does not increase above its normal full-flow maximum value.( }
Specification 15.3.1.A.3 provides limiting conditions for operation to ensure that redundancy in decay heat removal methods is provided. A single Reactor Coolant loop with its associated steam generator and a Reactor Coolant Pump or a single residual heat removal loop provide sufficient heat removal capacity for removing the reactor core decay heat; however, single failure considerations require that at least two decay heat removal methods be available. Operability of a steam generator for decay heat removal includes two sources of water, water level indication in the steam generator, a vent path to atmosphere, and the Reactor Coolant System filled and vented so thermal convection cooling of the core is possible.
If the steam generators are not available for decay heat removal, this Specification requires both residual heat removal loops to be operable unless the reactor system is in the refueling shutdown condition with the refueling cavity flooded and no operations in progress which could cause an increase in reactor decay heat load or a decrease in boron concentration.
In this conditione the reactor vessel is essentially a fuel storage pool and removing a RHR loop from service provides conservative conditions should operability problems develop in the other RHR loop.
Also, one residual heat removal loop may be temporarily out of service due to surveillance testing, calibration, or inspection requirements. The surveillance procedures follow administrative controls which allow for timely restoration of the residual heat removal loop to service if required.
Each of the pressurizer safety valves is designed to relieve 288,000 lbs, per hour of saturated steam at setpoint.
If no residual heat is removed by any of 15.3.1-3b
I I
the means available, the amount of steam which could be generated at safety valve relief pressure would be less than half the valves' capacity. One valve, therefore, provides adequate defense against overpressurization.
Below 350*F and 400 psig in the Reactor Coolant System, the residual heat removal system can remove decay heat and thereby control system temperature and pressure.
A PORV is defined as OPERABLF if leakage past the valve is less than that allowed in Specification 15.3.1.D and the PORV has met its most recent channel test as specified in Table 15.4.1-1.
The PORVs operate to relieve, in a controlled manner, Reactor Coolant System pressure increases below the setting of the pressurizer safety valves. The FORVs have remotely operated block valves to provide a positive shutoff capability should a PORV become inoperable.
The requirement that 100 KW of pressurizer heaters and their associated controls be capable of being supplied electrical power from an emergency bus provides assurance that these heaters can be energized during a loss of offsite power condition to maintain pressure control and natural circulation at hot standby.
The requirement to have a reactor coolant system gas vent operable from the reactor vessel or the pressurizer steam space assures that non-condensible gases can be released from the Reactor Coolant System if necessary. The Reactor Coolant Gas Vent System (RCGVS) provides an orificed vent path from the pressurizer steam space and an orificed vent path from the reactor vessel.
Both vent paths include two parallel solenoid-operated isolation valves which are powered from emergency buses and vent to a common header.
From the common header, gases may be vented via seperate lines, each with a single solenoid operated. iso-lation valve powered from the emergency bus to the pressurizer relief tank or containment atmosphere. The orifice in these vent lines restricts leakage so that, in the event of a pipe break or isolation valve failure, makeup water for the leakage can be provided by a single coolant charging pump.
If a RCGVS vent path from either the pressurizer or reactor vessel head is inoperable, Specification 15.3.1.A.7.c requires the remotely operable valves in 15.3.1-3c
that inoperable path to be shut with power removed.
If a vent path from the common header to the pressurizer relief tank or containment atmosphere is in-operable, the isolation valve in that path must be shut but reactor operations may continue. If both vent paths to or both vent paths from the common header are inoperable, the RCGVS is inoperable and the steps in specification 15.3.1.A.7.d must be taken.
(1) FSAR Section 14.1.6 (2) FSAR Section 7.2.3 15.3.1-3d t
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o TABLE 15.4.1-1 (4 of 4)
Channel No.
Description Check Calibrate Test Remarks 40.
Containment High Range Radiation S **
R M **
Calibration to be verification of response to a source.
41.
Containment Hydrogen Monitor D
R/Q d.A.
Gas Calibration - Q, Electronic Calibration - R Sample gas for calibration at 2% and 6% hydrogen.
42.
Reactor Vessel Fluid Level System M
R N.A.
43.
In-Core Thermocouple M
R N.A.
Calibration to be verification of response to a source.
S
- Each Shift M - Monthly D
- Daily P - Prior to each startup if not done previous week W
- Weekly R - Each refueling interval (but not to exceed 18 months)
Q
- Quarterly N. A. - Not applicable B/W - Biweekly Not required during periods of refueling shutdown, but must be performed prior to startup if it has not been performed during the previous surveillance period.
Not required during periods of refueling shutdown if steam generator vessel temperature is greater than 70 F.
a.
Performance of a channel functional test on the PORV actuation channel, but excluding valve operations, within 31 days prior to entering a condition in which the PORV is required operable and at least once per 31 days thereafter when the PORV is required operable.
b.
Testing valve operation in accordance with the inservice test requirements of the ASME Boiler and Pressure Vessel Code,Section XI.