ML20086Q810
| ML20086Q810 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 07/26/1995 |
| From: | ENTERGY OPERATIONS, INC. |
| To: | |
| Shared Package | |
| ML20086Q805 | List: |
| References | |
| NUDOCS 9507280201 | |
| Download: ML20086Q810 (7) | |
Text
-.
f
. EMERGENCY CORE COOLING SYSTEMS 3/4.5.2 ECCS SU85YSTEMS - MODES 1, 2. AND 3
- LJMITING CONDITI0h! FOR OPERATION 3.5.2 Two independent emergency core cooling system (ECCS) subsystems shall be OPERABLE with each subsystem comprised of:
a.
One OPERA 8LE high pressure safety injection' pump, b.
One OPERABLE low pressure safety injection pump, and 1
c.
An independent OPERABLE flow path capable of taking suction from the refueling water storage pool on a safety injection actuation signal and automatically transferring suction to the safety injection system sump on a recirculation actuation signal.
APPLICABILITY: MODES 1, 2, and 3*f.
1 ACTION:
a.
With one ECCS subsystem inoperable, restore the inoperable subsystem 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 at least HOT STAN08Y within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
i b.
In the event the ECCS is actuated and injects water into the Reactor Coolant System, a Special, Report shall be prepared and submitted to the Commission pursuant to Specification 6.9.2 within 90 days des-i cribing the circumstances of the actuation and the total accumulated actuation cycles to date. The current value of the usage factor for j
each affected safety injection nozzle shall be provided in this Special Report whenever its value exceeds 0.70.
el 5
"With pressurizer pressure greater than or equal to 1750 psia.
- With RCS average temperature greater than or equal to 500*F.
5 9507290201 950726 PDR ADOCK 05000382 P
PDR WATERFORD - UNIT 3 3/4 5-3 1
i
4 3I4.5 EMERGENCY CORE COOLING SYSTEMS (ECCS)
BASES 3/4.5.1 SAFETY INJECTION TANKS The OPERA 8ILITY of each of the Reactor Coolant System (RCS) safety injection tanks ensures that a sufficient volume of borated water will be innediately forced into the reactor core through each of the cold legs in the event the RCS pressure falls below the pressure of the safety injection tanks.
This initial surge of water into the core provides the initial cooling mechanism during large RCS pipe ruptures.
The limits on safety injection tank volume, boron concentration, and pressure ensure that the assumptions used for safety injection tank injection 4
in the safety analysis are met.
The safety injection tank power operated isolation valves are considered to be " operating bypasses" in the context of IEEE Std. 279-1971, which requires that bypasses of a protective function be removed automatically whenever permissive conditions are not met.
In addition, as these safety injection i
tank isolation valves fail to meet single failure criteria, removal of power to the valves is required.
The limits for operation with a safety injection tank inoperable for any reason except an isolation valve closed minimizes the time exposure of the plant to a LOCA event occuring concurrent with failure of an additional safety injection tank which may result in unacceptable peak cladding temperatures.
If a closed isolation valve cannot be immediately opened, the full capability of one safety injection tank is not available and prompt action is required to place the reactor in a mode where this capability is not required.
3/4.5.2 and 3/4.5.3 ECCS SUBSYSTEMS l
The OPERABILITY of two separate and independent ECCS subsystems ensures that sufficient emergency core cooling capability will be available in the event of a LOCA assuming the loss of one subsystem through any single failure consideration.
Either subsystem operating in conjunction with the safety injection tanks is capable of supplying sufficient core cooling to limit the peak cladding temperatures within acceptable limits for all postulated break sizes ranging from the double-ended break of the largest RCS cold leg pipe downward.
In addition, each ECCS subsystem provides long-term core cooling capability in the recirculation mode during the accident recovery period.
When in mode 3 and with RCS temperature 5000F two OPERABLE ECCS subsys-l tems are required to ensure sufficient emergency core cooling capability is available to prevent the core from becoming critical during an uncontrolled cooldown (i.e., a steam line break) from greater than 5000F.
WATERFORD - UNIT 3 B 3/4 5-1 Amendment No. 34
7_ _
d EMERGENCY CORE COOLING SYSTEMS BASES ECCS SUBSYSTEMS (Continued)
With the RCS temperature below 350*F, one OPERABLE ECCS subsystem is acceptable without single failure consideration on the basis of the stable reactivity condition of the reactor and the limited core cooling requirements.
The trisodium phosphate dodecahydrate (TSP) stored in dissolving baskets located in the containment basement is provided to minimize the possibility of corrosion cracking of certain metal components during operation of the ECCS following a LOCA.
The TSP provides this protection by dissolving in the sump water and causing its final pH to be raised to greater than or equal to 7.0.
The Surveillance Requirements provided to ensure OPERABILITY of each component ensure that at a minimum, tne assumptions used in the safety analyses are met and that subsystem OPERABILITY is maintained.
Surveillance Requirements for throttle valve position stops and flow balance testing pro-vide assurance that proper ECCS flows will be maintained in the event of a LOCA. Maintenance of proper flow resistance and pressure drop in the piping system to each injection point is necessary to:
(1) prevent total pump flow from exceeding runout conditions when the system is in its m'inimum resistance configuration, (2) provide the proper flow split between injection points in accordance with the assumptions used in the ECCS-LOCA analyses, and (3) provide an acceptable level of total ECCS flow to all injection points equal to or above that assumed in the ECCS-LOCA analyses.
The requirement to dissolve a representative sample of TSP in a sample of water borated within RWSP boron concentration limits provides assurance that the stored TSP will dissolve in borated water at the postulated post-LOCA temperatures.
The requirement to verify the minimum pump discharge pressure on recircula-tion flow ensures that the pump performance curve has not degraded below that used to show that the pump exceeds the design flow condition assumed in the safety analysis and is consistent with the requirements of ASME Section XI.
3/4.5.4 REFUELING WATER STORAGE POOL (RWSP)
The OPERABILITY of the refueling water storage pool (RWSP) as part of the ECCS also ensures that a sufficient supply of borated water is available for injection by the ECCS in the event of a LOCA.
The limits on RWSP minimum volume and baron concentration ensure that (1) sufficient water is available within containment to permit recirculation cooling flow to the core, and (2) the reactor will remain subcritical in the cold condition following mixing of the RWSP and the RCS water volumes with all CEAs inserted except for the most reactive control assembly.
These assumptions are consistent with the LOCA analyses.
WATERFORD - UNIT 3 B 3/4 5-2
h '
M 0
E t
f i
h i
NPF-38-168 ATTACHMENT B i
i e
[
i I
e-EMERGENCY CORE COOLING SYSTEMS f
3/4 5.2 ECCS SUBSYSTEMS - MODES 1. 2. AND 3 LIMITING CONDITION FOR OPERATION l
i 1
3.5.2 Two independent emergency core cooling system (ECCS) subsystems shall be OPERABLE with each subsystem comprised of:
a.
One OPERABLE high-pressure safety injection pump.
b.
One OPERABLE low-pressure safety injection pump, and c.
An independent OPERABLE flow path capable of taking suction from the refueling water storage pool on a safety injection actuation signal and automatically i
transferring suction to the safety injection system sump on a recirculation actuation signal.
APPLICABILITY: MODES 1. 2. and 3*#.
ACTION:
a.
With one low pressure safety injection subsystem inoperable, restore the inoperable i
subsystem to OPERABLE status within 7 days or be in at least HOT STANDBY within the 4
next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
b av With one ECCS subsystem inoperable due to conditions other than (a), restore the l
inoperable subsystem 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 at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN within the following 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
cJr In the event the ECCS is actuated and injects water into the Reactor Coolant System.
l a Special Report shall be prepared and submitted to the Comission pursuant to Specification 6.9.2 within 90 days describing the circumstances of the actuation and the total accumulated actuation cycles to date. The current value of the usage factor for each affected safety injection nozzle shall be provided in this Special Report whenever its value exceeds 0.70.
i f
- With pressurizer pressure greater than or equal to 1750 psia.
- With RCS average temperature greater than or equal to 500F, WATERFORD - UNIT 3 3/4 5-3
c 3/4.5 EMERGENCY CORE COOLING SYSTEMS (ECCS)
BASES 3/4.5.1 SAFETY INJECTION TANKS The OKRABILITY of each of the Reactor Coolant System (RCS) safety injection tanks ensures that a sufficient volume of borated water will be immediately forced into the reactor core through each of the cold logs in the event the RCS pressure falls below the pressure of the safety injection tanks. This initial surge of water into the core provides the initial cooling mechanism during large RCS pipe ruptures.
The limits on safety injection tank volume, boron concentration, and pressure ensure j
that the assumptions used for safety injection tank injection in the safety analysis are met.
The safety injection tank power operated isolation valves are considered to be i
" operating bypasses" in the context of IEEE Std. 279-1971, which requires that bypasses of a protective function be removed automatically whenever permissive conditions are not met. In addition, as these safety injection tank isolation valves fail to meet single failure criteria, removal of power to the valves is required.
The limits for operation with a safety injection tank inoperable for any reason except an isolation valve closed minimizes the time exposure of the plant to a LOCA event occurring concurrent with failure of an additional safety injection tank which may result in unacceptable peak cladding temperatures. If a closed isolation valve cannot be immediately opened, the full capability of one safety injection tank is not available and prompt action is required to place the reactor in a mode where this capability is not required.
3/4.5.2 and 3/4.5.3 ECCS SUBSYSTEMS The OPERABILITY of two separate and independent ECCS subsystems ensures that sufficient emergency core cooling capability will be available in the event of a LOCA with a loss of offsite power assuming the loss of one subsystem through any single failure consideration. Either subsystem operating in conjunction with the safety injection tanks is I
capable of supplying sufficient core cooling to limit the peak cladding temperatures within acceptable limits for all postulated break sizes ranging from the double-ended break of the largest RCS cold leg pipe downward. In addition, each ECCS subsystem provides long-term core cooling capability in the recirculation mode during the accident recovery period.
Each subsystem includes the piping, instruments, and controls to ensure the availability of an OPERABLE flowpath capable of taking suction from the RWSP on an SIAS and automatically transferring suction to the containment sump upon a recirculation actuation signal (RAS). The flowpath for each subsystem must maintain its designed independence to ensure that no single failure can disable both ECCS trains.
3.5.2. ACTION (a) addresses the specific condition where the only affected ECCS subsystem is a single LPSI subsystem. A LPSI subsystem consists of a pump, and two injection flow paths, including motor-operated valves operated by a common AC power source.
l WATERFORD - UNIT 3 B 3/4 5-1 AMENDMENT NO. 34
l EMERGENCY CORE COOLING SYSTEMS
+
BASES ECCS SUBSYSTEMS (Continued)
An ECCS train is inoperable if it is not capable of delivering the design flow to the RCS. The individual components are inoperable if they are not capable of performing their design function, or if supporting systems are not available.
If LCO 3.5.2 requirements are not met due to the condition described in ACTION (a),
then the inoperable LPSI subsystem components must be returned to OPERABLE status within seven (7) days of discovery. This seven (7) day completion time is based on the findings of deterministic and probabilistic analysis, CE NPSD-995. "CE0G Joint Applications Report for Low Pressure Safety Injection System A0T Extension," April 1995. Seven (7) days is a reasonable amount of time to perform many corrective and preventative maintenance items on the affected LPSI subsystem.
ACTION (b) addresses other scenarios where a subsystem would be unavailable. If conditions of ACTION (b) exists, then inoperable components must be restored within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> of discovery. The 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> completion time is base on an NRC reliability study ( NRC Memorandum to V. Stello, Jr., from R.L. Baer, " Recommended Interim Revisions to LCOs for ECCS Components " December 1,1975 ) and is a reasonable amount of time to effect many repairs.
When in Mode 3 and with RCS temperature 500*F two OPERABLE ECCS subsystems are required to ensure sufficient emergency core cooling capability is available to prevent the core from becoming critical during an uncontrolled cooldown (i.e., a steam line break) from greater than 500*F.
With the RCS temperature below 350*F, one OPERABLE ECCS subsystem is acceptable without single failure consideration on the basis of the stable reactivity condition of the reactor and the limited core cooling requirements.
I The trisodium phosphate dodecahydrate (TSP) stored in dissolving baskets located in the containment basement is provided to minimize the possibility of corrosion cracking of certain metal components during operation of the ECCS following a LOCA. The TSP provides this protection by dissolving in the sump water and causing its final pH to be raised to greater than or equal to 7.0.
The Surveillance Requirements provided to ensure OPERABILITY of each component ensure that at a minimum, the assumptions used in the safety analyses are met and that subsystem OPERABILITY is maintained. Surveillance Requirements for throttle valve position stops and i
flow balance testing provide assurance that proper ECCS flows will be maintained in the event of a LOCA. Maintenance of proper flow resistance and pressure drop in the piping system to each injection point is necessary to: (1) prevent total pump flow from exceeding runout conditions when the system is in its minimum resistance configuration. (2) provide the proper flow split between injection points in accordance with the assumptions used in the ECCS-LOCA analyses, and (3) provide an acceptable level of total ECCS flow to all injection points equal to or above that assumed in the ECCS-LOCA analyses.
WATERFORD - UNIT 3 8 3/4 5-2
.