ML19323B823
| ML19323B823 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 05/09/1980 |
| From: | TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML19323B816 | List: |
| References | |
| NUDOCS 8005140307 | |
| Download: ML19323B823 (8) | |
Text
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O 8005140 307 ENCLOSURE PROPOSED CHANGES TO BROWNS FERRY NUCLEAR PLANT UNITS 1, 2, AND 3 t
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BROWNS FERRY UNIT 1, MD E
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e REVIGED 6/22/78 LIllITI.NC CONo:TIONS FOR OPERATICN SURVEILLANCE RFOUIREMEtiTS 3.7 COTTA It4MEr.T SYSTP_MS
4.7 CONTAIt
met;T SYSTEMS Containment Atmosohere Monitoring (CAM Systen -
H.
Containment Atnosphere Analy7er Monitoring (C Nt} System -
g Analv er 1.
Whenever the reactor is not in cold
- 1. a. Once per montit shutdown, two gas perform a channel analyzer systems calibration using' shall be operable for standard gas samples monitoring the drywell.
containing a nominal three volume precent 2.
Whenever the reactor hydrogen, balance. nitrogen.
is not in cold shutdown, one gas analyzer system i
shall be operable for monitoring the torus.
- b. Under accident monitoring conditions, a channel calibration shall be per-formed any time the ambient tempera-ture changes more than 27 F from the temperature at which the last calibration was performed.
3.
'If specification l
- 3. 7. H.1 cannot be net, but one system remains operable, the reactor may be opera ted for a period of 30 days.
If both systems are inope ra bl e, the reactor should be placed in shutdcwn-condition within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
4' If specification 3.7.11.2 cannot be met, the reactor may be Dgn operated for a period yy
[]O of 30 days.
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( f 249 6
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BASES The occurrence of primary system leakage following a major refueling outage or other scheduled shutdown is much more probable than the occurrence of the loss-of-coolant accident upon which the specified oxygen concentration limit is based.
Permitting access to the drywell for leak inspections
'during a startup is judged prudent in terms of the adde'd plant safety offered without significantly reducing the margin of safety.
Thus, to preclude the possibility of starting the reactor and operating for extended periods of time with significant leaks in the primary system, leak inspections are scheduled during startup periods, when the primary system is at or near rated operating temperature and pressure. The 24-hour period to provide inerting is judged to be suf ficient to perform the leak inspection and establish the required oxygen concentration.
To ensure that the hydrogen concentration is maintained less than 4% following an accident, liquid nitrogen is maintained on-site for containment atmosphere dilution. About 2260 gallons would be sufficient as a 7-day supply, and replenishment facilities can deliver liquid nitrogen to the site within one day; therefore, a requirement of 2500 gallons is conservative.
Following a loss of coolant accident the Containment Air Monitoring (CAM) System con-tinuously monitors the hydrogen concentration af,ter an initial calibration period. A recalibration will be required if the temperature in the containment differs more than 27 F from 'the previous CAM calibration condition.
Two independent systems (a system consists of one hydrogen sensing circuit) are installed in the drywell and one system is installed in the torus.
Each sensor and associated circuit is periodically checked by a calibration gas to verify operation.
Failure of a drywell system does not reduce the ability to monitor system atmosphere as a second independent and redundant system will still be operable.
,e In terms of separability, redundancy for a failure of the torus system is based upon at least one operable drywell system.
The drywell hydrogen concentration can be used to limit the torus hydrogen concentration during post LOCA conditions. Post LOCA calculations show that the CAD system initiated within two hours at a flow rate of 100 scfm will limit the peak drywell and wetwell hydrogen con-centration to 3.6% (at 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />),nd 3.87 (at 32 hours3.703704e-4 days <br />0.00889 hours <br />5.291005e-5 weeks <br />1.2176e-5 months <br />), respectively.
This is based upon purge initiation after 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> at a flow rate of 100 scfm to maintain containment pressure below 30 psig.
Thus, peak torus hydrogen concentration can be controlled below 4.0 percent using either the direct torus hydrogen monitoring system or the drywell hydrogen monitoring system with appropriate conservatism (< 3.8%),
as a guide for CAD / Purge operations.
For the period of time during which the hydrogen monitors are being recalibrated, hydrogen concentrations below 4% are assured if the CAD system is initiated within 30 minutes of the LOCA.
270 h
D 4.
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BROWNS FERRY UNIT 3 6
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l
REn3ED 6/22/78 LillITING CO301TIOMS FOR OPERATION SU RVEI LI.ANCE REQUIREMENTS 3.7 CorcA INMEPC SYSTEMS
4.7 CONTAIt
MENT SYSTEMS containment Atmosonere Monitortnq (CAN Syst m -
H.
Containment Atmosphere ff, An a ly r er Monitoring (CNi) System -
H Analyzer g
1.
Whenever the reactor is not in cold 1.a.
Once per month shutdown, two gas
. perform a channel analyzer systems calibration using-shall be operabic for standard gas samples monitoring the drywell.
containing a nominal three volume precent 2.
Whenever the reactor hydrogen, balance. nitrogen.
is not in cold shutdown, one gas analyzer system shall be operable for
~
I monitoring the torus,
- b. Under. accident monitoring conditions, a channel calibration shall be per-formed any time the ambient tempera-ture changes more than 27 F from the temperature at which the last calibration was performed.
3.
If specification
- 3. 7. H.1 cannot be tee t, but one system I
remains operable, the reactor may be opera ted for a period of 30 days.
If bo th systems are inoperabic, the reactor should be placed in shutdown con di tion within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
4*
If specification
- 3. 7.11.2 cannot be met,
the reactor may be operated for a period of 30 days.
i 261 3
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Inertino REVISED 6/22/78 The relatively small containment volume inherent in the GE-BWR preocure suppression containment and the large amount of zirconium in the core are auch that the occurrence of a very limited (a percent or oo) reaction of the zirconium and steam during a lonn-of-coolant accident could lead to the liberation of hyr rogen combi 7ed with an air atmosphere to result in a flammable i
concentration in the containment.
If a suf ficient amount of hydrogen is generated and oxygen _ is available in stoichiometric quantities, the subsequent ignition of the hydrogen in rapid recombination rate could lead to f ailure of the containment to maintain Icv leakage integrity.
The
<4~, hydror,en concentration minimi~ es the possibility of hydrogen combustion follcwing a loss-of-coolant accident.
~
The occurrence of primary system leakage following a major refueling outage or other scheduled shutdown is much more probable than the occurrence of the loss-of-coolant accident upon which the specified oxygen concentration limit is based. Permitting access to the drywell for leak inspections
'during a startup is judged prudent in terms of the adde'd plant safety offered without significantly reducing the margin of safety.
Thus, to preclude the possibility of starting the reactor and operating for extended periods of time with significant leaks in the primary system, leak inspections are scheduled during startup periods, when the primary system is at or near rated operating temperature and pressure.
The 24-hour period to provide inerting is judged to be suf ficient to perform the leak inspection and establish the required oxygen concentration.
To ensure that the hydrogen concentration is maintained less than 4% following an accident, liquid nitrogen is maintained on-site for containment atnosphere dilution. About 2260 gallons would be sufficient as a 7-day supply, and replenishment facilities can deliver liquid nitrogen to the site within one day; therefore, a requirement of 2500 gallons is conservative.
Following a loss of coolant accident the Containment Air Monitoring (CAM) System con-tinuously monitors the hydrogen concentration after an initial calibration period. A recalibration will be required if the temperature in the containment differs more than 27 F from t'he previous CAM calibration condition.
Two independent systems (a system consists of one hydrogen sensing circuit) are installed in the drywell and one system is installed in the torus.
Each sensor and associated circuit is periodically checked by a calibration gas to verify operaticn.
Failure of a drywell system does not reduce the ability to monitor system atmosphere as a second independent and redundant system will still be operable.
286A
- 9
In terms of separability, redundancy for a failure.of the torus system is based upon at'least one operable drywell system. The drywell hydrogen concentration can be used to limit the torus hydrogen concentration during post LOCA conditions.
Post LOCA calculations show that the CAD system initiated within two hours at a flow rate of 100 scfm will limit the peak drywell and wetwell hydrogen con-centration to 3.6% (at 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br />) and 3.87 (at 32 hours3.703704e-4 days <br />0.00889 hours <br />5.291005e-5 weeks <br />1.2176e-5 months <br />), respectively.
This 1.s based upon purge initiation af ter 20 hours2.314815e-4 days <br />0.00556 hours <br />3.306878e-5 weeks <br />7.61e-6 months <br /> at a flow rate of 100 scfm to maintain containment pressure below 30 psig.
Thus, peak torus hydrogen concentration can be controlled below 4.0 percent using either the direct torus hydrogen monitoring system or the drywell hydrogen monitoring system with appropriate conservatism (13.8%),
as a guide for CAD / Purge operations.
For the period of time during which the hydrogen monitors are being recalibrated, hydrogen concentrations below 4% are assured if the CAD system is initiated within 30 minutes of the LOCA.
I Vacuum Relief The purpose of the vacuum relief 'ralves is to equalize the pressure between the drywell and suppression chamber and reactor building so that the structural integrity of the containment is maintained.
The vacuum relief system frczn the pressure suppression chamber to reactor buiding conuists of two 100%
vacuum relief breakers (2 parallel sets cf 2 valves in series).
Operation.of either system will maintain the pressure diff erential less than 2 psig; the external design pressure.
One reactor building vacuum breaker may be out of service for repairs for a period of seven days.
If repairs cannot be completed within oeven days, the reactor coolant system is brought to a ccndition where vacuum relief is no longer required.
When a drywell-suppression chamber vacuum breaker valve is emercised through an opening-closing cycle the position indicating lights in the control rocm are designed to function as specified below:
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