ML20059M056
| ML20059M056 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 09/26/1990 |
| From: | NRC |
| To: | |
| Shared Package | |
| ML20059M053 | List: |
| References | |
| NUDOCS 9010030036 | |
| Download: ML20059M056 (2) | |
Text
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EMERGENCY CORE COOLING SYSTEMS g
EASES ECCS SUBSYSTEMS (Continued)
With the Main Coolant System temperature and pressure below 330'F, and l000 psig, respectively, one OPERABLE ECCS safety injection subsystem, with the OPERABLE recirculation subsysten and the OPERABLE long term hot leg injection subsystem, is acceptable without single failure consideration on th basis of the stable reactivity conditien of the reactor, the decreased probability of a LOCA and the limited core ecoling requirements because of the negligible energy stored in the primary coolant under these conditions.
The Surveillance Requirements prosided to ensure OPERABILITY of each component ensures that, at a minimum, the assumptions used in the safety analyses are met and that subsystem OPERABILITY is maintained.
Complete system tests cannot be performed when the reactor is operating because of their inter-relation with operating systems. The method of assuring operability of these systems is a combination of enmplete system tests performed during refueling shutdowns and inservice testing of active system components (pumps and valves) duriag reactor operation.
The test interval is based on the judgement that more frequent testing would not significantly increase reliability.
Some subsystems power operated valves fail to acet single f ailure criteria and removal of power to these valves is required.
In order to eliminate potential for reactor vessel low temperature overpressurization by the inadvertent operation of ECCS pumps, the pump circuit breakers are opened and locked in the racked-out position or removed from the breaker cubicles. Also selected SIS isolation valves are positioned to remove the possibility of an overpressurization event during that portion of MCS heatup and cooldown when an inadvertent injection could result in an overprensure event.
i/4.5.4 SU ETY INJECTION TANK The OPERABILITY of the Safety Injection Tank (SIT) as part of the ECCS ensures that a sufficient supply nf borated water la available for injection by the ECCS in the event of a LOCA. The limits on SIT minimum level and l
boron concentration ensure that 1) suf ficient water is available within l
containment to permit recirculation cooling flow to the core, and 2) the reactor will remain suberitical in the cold condition following mixing of the SIT and the Main Coolant System water volumes with all control rods inserted except for the most reactive control assembly. These assumptions are consistent with the LOCA analyses, which is based on allowing a minimum l
of 77,000 gallons to be injected by the safety injection subsystems before the recirculation is manually established. LOCA analyses show that an injection of 77,000 gallons is sufficient to limit core temperatures and i
containment pressure for the full spectcum of pipe ruptutea.
This leaves up to 52,000 gallons in the SIT as reserve. The boron coacentration of 2200 ppm is the highest value assumed in any accident analysis.
The SIT water temperature of 120'F to 130*F ensures that the reactor vessel is not subjected to conditions that could exceed the NDT provisions of the ASME Code after a severe transient.
YANYFF-ROWF B 3/4 S-2 Amendment No. 52, 59, 92, Z35, 136 9010030036 900926 PDR ADOCK 05000029 P
t EAERGENCY CORE COOLING SYSTEMS SAFETY INJECTION TANK LIMITING CONDITION FOR OPERATION 3.5.4 The safety injection tank (SIT) shall be CPERABLE with:
a.
A minimum contained borated water volune equivalent to a level of 125.5 feet.
b.
A minimum boron concentration of 2200 ppm, and t
c.
A water temperature of 120*F to 130'F ##.
APPLICABILITY: MODES 1, 2, 3, 4*,
- and 6#.
ACTION:
With the safety injection tank inoperable, restore the tank to OPERABLE status within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or be in at least HOT STANDBY within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in HOT SHUTDOWN with main coolant pressure <300 psig within the following 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
SURVEILLANCE REOUIREMENTS i
4.5.4 The SIT shall be demonstrated OPERABLE:
a.
At least once per 7 days by:
1.
Verifying the contained borated water volume in the tank, and 2.
Verifying the boron concentration of the water.-
b.
At least once per 24 hout,9 by verifying the SIT temperature.
l Main coolant pressure 1300 psig.
- Whenever Special Test Exceptions 3.10.5, 3.10.6, or 3.10.7 for REDUCED LEVEL OPERATION are applicable.
- Not required for REDUCED LEVEL OPERATION.
t YANKEE-ROWE J/4 5-12 Amendment No. 49, 59, 92, Z3#, 136 l
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