ML20134D219
| ML20134D219 | |
| Person / Time | |
|---|---|
| Site: | Quad Cities  |
| Issue date: | 01/27/1997 |
| From: | COMMONWEALTH EDISON CO. |
| To: | |
| Shared Package | |
| ML20134D214 | List: |
| References | |
| NUDOCS 9702050028 | |
| Download: ML20134D219 (4) | |
Text
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j ATTACHMENTI Marked-Up Technical specification Bases Page s
9702050028 970127 PDR ADOCK 05000254 P
CONTAINMENT SYSTEMS B 3/4.7 BASES discontinuities in the vicinity of the relief valve discharge since these are expected to be the points of highest stress.
Under full power operating conditions, blowdown from an initial suppression chamber water temperature of 95'F results in a water temperature of approximately 145'F immediately following %
blowdown which is low enough to provide complete condensation via T-quencher devices.[At is
' tempera and at ospheric pre sure, the pvailable ne positive suc 'on head e eeds )t *bt req '
y the ergency co cooling yetem pum, thus there ' no dep ency 9tf s
c ainment orpressure ring the accident inj ion phase.
' Experimental data indicates that excessive steam condensing loads can be avoided if the peak temperature of the suppression pool is maintained sufficiently low during any period of safety relief valve operation for T-quencher devices. Specifications have been placed on the envelope of reactor operating conditions so that the reactor can be depressurized in a timely manner to avoid the regime of potentially high suppression chamber loadings. In addition to the limits on temperature of the suppression chamber pool water, operating procedures define the action to be taken in the event a safety or relief valve inadvertently opens or sticks open. As a minimum this action shall include: (1) use of all available means to close the valve, (2) initiate suppression pool water cooling, (3) initiate reactor shutdown, and (4) if other safety or relief valves are used to depressurize the reactor,'their discharge shall be separated from that of the stuck-open safety or rehef valve to assure mixing and uniformity of energy insertion to the pool.
In conjunction with the Mark i Containment Short Term Program, a plant unique analysis was performed which demonstrated a factor of safety of at least two for the weakest element in the suppression chamber support system and attached piping. The maint3 nance of a drywell.
I suppression chamber differential pressure and a suppression chamber water level corresponding to a downcomer submergence range of 3.67 to 4.00 feet will assure the integrity of the suppression chamber when subjected to post-LOCA suppression pool hydrodynamic forces.
3/4.7.L Suppression Chamber and Drywell Sorav Following a Design Basis Accident (DBA), the suppression chamber spray function of the containment cooling mode of the residual heat removal (RHR) system removes heat from the suppression chamber air space and condenses steam. The suppression chamber is designed to absorb the sudden input of heat from the primary system from a DBA or a rapid depressurization of the reactor pressure vessel through safety or relief valves. There is one 100% capacity I
containment spray header inside the suppression chamber.
Periodic operation of the suppression chamber and drywell sprays may also be used following a DBA to assist the natural convection and diffusion mixing of hydrogen and oxygen when other ECCS requirements are met and oxygen concentration exceeds 4%. Since the spray system is a function of the RHR system, the loops will not be aligned for the spray function during normal operation, but at: components required to operate for proper alignment must be OPERARLE.'
1 QUAD CITIES - UNITS 1 & 2 B 3/4.7-6 Amendment Nos.
171 s i n j
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L
ATTACHMENT 2 4
Re-Typed Technical Specification Bas:s Page 1
i c
l CONTAINMENT SYSTEMS B 3/4.7
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BASES discontinuities in the vicinity of the relief valve discharge since these are expected to be the points of highest stress.
Under full power operating conditions, blowdown from an initial suppression chamber water temperature of 95 F results in a water temperature of approximately 145 F immediately following blowdown which is low enough to provide complete condensation via T-quencher devices.
Experimental data indicates that excessive steam condensing loads can be avoided if the peak temperature of the suppression pool is maintained sufficiently low during any period of safety relief valve operation for T-quencher devices. Specifications have been placed on the envelope of reactor I
operating conditions so that the reactor can be depressurized in a timely manner to avoid the regime of potentially high suppression chamber loadings. In addition to the limits on temperature of the suppression chamber pool water, operating procedures define the action to be taken in the event a safety or relief valve inadvertently opens or sticks open. As a minimum this action shall include: (1) use of cll available means to close the valve, (2) initiate suppression pcol water cooling, (3) initiate reactor shutdown, and (4) if other safety or relief valves are used to depressurize the reactor, their dis: Sarge shall be separated from that of the stuck-open safety or relief valve to assure mixing and uniformity of energy insertion to the pool.
in conjunction with the Mark i Containment Short Term Program, a plant unique analysis was performed which demonstrated a factor of safety of at least two for the weakest element in the suppression chamber support system and attached piping. The maintenance of a drywell-suppression chamber differential pressure and a suppression chamber water level corresponding to a downcomer submergence range of 3.67 to 4.00 feet will assure the integrity of the suppress lor' chamber when subjected to post-LOCA suppression pool hydrodynamic forces.
3/4.7.L Suooression Chamber and Drvwell Sorav Following a Design Basis Accident (DBA), the suppression chamber spray function of the containment cooling mode of the residual heat removal (RHR) system removes heat from the suppression chamber air space and condenses steam. The suppression chamber is designed to absorb the sudden input of heat from the pnmary system from a DBA or a rapid de;vessurization of the reactor pressure vessel through safety or relief valves. There is one 100% capacity containment spray header inside the suppression chamber.
Periodic operation of the suppression chamber and drywell sprays may also be used following a DBA to assist the natural convection and diffusion mixing of hydrogen and oxygen when other ECCS requirements are met and oxygen concentration exceeds 4E Since the spray system is a function of the RHR system, the loops will not be aligned for the spray function during normal operation, but all components required to operate for proper alignment must be OPERABLE.
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l QUAD CITIES - UNITS 1 & 2 B 3/4.7-6 Amendment Nos.
171 & 167 l
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