ML18036A475
| ML18036A475 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 12/06/1991 |
| From: | TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML18036A474 | List: |
| References | |
| NUDOCS 9112120143 | |
| Download: ML18036A475 (13) | |
Text
ENCLOSURE I
'ROPOSED TECHNICAL SPECIFICATION CHANGE BROGANS FERRY NUCLEAR PLANT UNIT 2 DOCKET NOS. 50-260 (TVA-BFN-TS-305)
PROPOSED TECHNICAL SPECIFICATION CHANGE
.7 4.7 CONTAINME YSTEMS LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS 3.7.F.
Prima
~Sstem Containment Pur e
4.7.F.
Primar Containment Pur e
~Sstem 3.7.F.3 (Continued) these primary containment isolation valves is governed by Technical Specification 3.7.D.
b.
Pressure control of the containment is normally performed by VENTING through 2-inch primary containment isolation valves which route effluent to the Standby Gas Treatment System.
The OPERABILITY of these primary containment isolation valves is governed by Technical Specification 3.7.D.
Dilution S stem CAD 3.7.G.
Containment Atmos here 4.7.G.
Containment Atmos here Dilution S stem CAD 1.
The Containment Atmosphere Dilution (CAD) System shall be OPERABLE with:
1.
S stem 0 erabilit a ~
Two independent systems capable of supplying nitrogen to the drywell and torus.
NOTE:
Any time during cycle 6 operation and prior to Unit 2 cycle 7
- startup, CAD system "B"
may be inoperable.
During that time, only one independent system is required.
a.
Cycle each solenoid operated air/nitrogen valve through at least one complete cycle of full travel in accordance with Specification 1.0.MM, and at least once per month verify that each manual valve in the flow path is open.
b.
A minimum supply of 2,500 gallons of liquid nitrogen per system.
b.
Verify that the CAD System contains a
minimum supply of 2,500 gallons of liquid nitrogen twice per week.
BFN Unit 2 3.7/4.7-22
7/'4.7 CONTAINMENT SYSTEMS LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS 3.7.G.
Containment Atmos here Dilution S stem CAD 4.7.F.
Containment Atmos here Dilution S stem CAD 2.
The Containment Atmosphere Dilution (CAD) System shall be OPERABLE whenever the reactor is in the RUN MODE.
- 3. If one system is inoperable, the reactor may remain in operation for a period of 30 days provided all active components in the other system are OPERABLE.
NOTE:
Any time during cycle 6 operation and prior to Unit 2 cycle 7 startup, no action is required if "B" CAD system is inoperable.
During this time if "A" CAD system is inoperable, the reactor may remain in operation for a period of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
- 4. If Specifications 3.7.G.l and 3.7.G.2, or 3.7.G.3 cannot. be met, an orderly shutdown shall be initiated and the reactor shall be in the COLD SHUTDOWN CONDITION within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
5.
Primary containment pressure shall be limited to a maximum of 30 psig during repressurization following a loss of coolant accident.
BFN Unit 2 3.7/4.7-23
c tu ft Hinimum 4 of Operable Instrument Channel
~tn trnnent e LI-3-58A LI-3-588 TABLE 3.2.F Surveillance Instrumentation Instrument Reactor Water Level Type Indication and Ran e
Indicator -155" to
+60"
~Mote (1) (2) (3)
PI-3-74A PI-3-748 Reactor Pressure Indicator 0-1200 psig (1) (2) (3)
XR-64-50 PI-64-678 TI-64-52AB Drywell Pressure Recorder 0-80 psia Indicator 0-80 psia (1) (2) (3)
XR-64-50 Orywell Temperature
- Recorder, Indicator (1) (2) (3) 0-4004F c
M I
XR-64-52 N/A N/A PS-64-678 TS-64-52A &
PIS-64-58A IS-64-67A LI-84-2A LI-84-13A Suppression Chamber Air Temperature Control Rod Position Neutron Honi toring Drywell Pressure Orywell Temperature and Pressure and Timer CAD Tank "A" Level CAD Tank "8" Level Recorder 0-400'F 6V Indicating
)
Lights
)
- SRH, IRH, LPRH
)
0 to 100K power
)
Alarm at 35 psig
)
)
Alarm if temp.
)
> 281 Fand
)
pressure
>2.5 psig
)
after 30 minute
)
del ay
)
Indicator 0 to 100%
Indicator 0 to 1001 (1) (2) (3)
(1) (2) (3) (4)
(1) (2) (3) (4)
(1) (10)
NOTES FOR TABLE
.2 F From and after the date that one of these parameters is reduced to one indication, continued operation is permissible during the succeeding 30 days unless such instrumentation is sooner made OPERABLE.
(2)
From and after the date that one of these parameters is not indicated in the control room, continued operation is permissible during the succeeding seven days unless such instrumentation is sooner made OPERABLE.
(3) If the requirements of notes (1) and (2) cannot be met, and if one of the indications cannot be restored in (6) hours, an orderly shutdown shall be initiated and the reactor shall be in a COLD SHUTDOWN CONDITION within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
(4)
These surveillance instruments are considered to be redundant to each other.
From and after the date that both the acoustic monitor and the temperature indication on any one valve fails to indicate in the control room, continued operation is permissible during the succeeding 30 days, unless one of the two monitoring channels is sooner made OPERABLE.'f both the primary and secondary indication on any SRV tailpipe is inoperable, the torus temperature will be monitored at least once per shift to observe any unexplained temperature increase which might be indicative of an open SRV.
(6)
A channel consists of eight sensors, one from each alternating torus bay.
Seven sensors must be OPERABLE for the channel to be OPERABLE.
(7)
When one of these instruments is inoperable for more than seven days, in lieu of any other report required by Specification 6.9.1.4, prepare and submit a Special Report to the Commission pursuant to Specification 6.9.2 within the next seven days outlining the action taken, the.cause of inoperability, and the plans and schedule for restoring the system to OPERABLE status.
(8)
Wi'th the p 1 ant in REACTOR POWER OPERATION p STARTUP CONDITIONS HOT STANDBY CONDITION OR HOT SHUTDOWN CONDITION and with the number of OPERABLE channels less than the required OPERABLE channels, either restore the inoperable channel(s) 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 initiate the preplanned alternate method of monitoring the appropriate parameter.
(9)
Noble Gas only (10)
Anytime during cycle 6 operation and prior to Unit 2 cycle 7
- startup, LI-84-13A is not required if CAD System B is inoperable.
BFN Unit 3.2/4.2-33
ENCLOSURE 2 0'ROPOSED TECHNICAL SPECIFICATION CHANGE BROWNS FERRY NUCLEAR PLANT UNIT 2 DOCKET NOS.
50-.260 (TVA-BFN-TS-305)
DESCRIPTION AND JUSTIFICATION FOR CHANGES
ENCLOSURE 2
DESCRIPTION AND JUSTIFICATION BROVHS FERRY NUCLEAR PLANT (BFN)
REASON FOR CHANGE On October 16, 1991, BFN staff discovered that containment air dilution (CAD) tank B was venting nitrogen at an unusually high rate and that the vacuum in the insulation space surrounding the tank had degraded.
Efforts to locate and repair the leak confirmed that the leak was not due to atmosphere entering the vacuum space from outside the tank and therefore the leak is believed to be the internal liquid nitrogen storage tank leaking nitrogen gas into the space.
Location and repair of such a leak requires cutting into the outer shell of the tank and possibly extensive disassembly.
This repair will likely require more time than the 30 days allowed by technical specifications and a forced plant shutdown would be required without temporary relief.
I.
Existin TS Pa e
3 4
-22 reads:
3.7.G.l The Containment Atmosphere Dilution (CAD) system shall be OPERABLE with:
a.
Two independent systems capable of supplying nitrogen to the drywell and torus.
Chan e TS to add a note to Section
.7 G l.a NOTE:
Any time during cycle 6 operation and prior to Unit 2 cycle 7
- startup, CAD system "B" may be inoperable.
During that time, only one independent system is required.
II. Existin TS Pa e
3 7 4.7-23 reads:
3.7.G.3 If one system is inoperable, the reactor may remain in operation for a period of 30 days provided all active components in the other system are OPERABLE.
Chan e TS to add a note to Section G
NOTE:
Any time during cycle 6 operation and prior to Unit 2 cycle 7
- startup, no action is required if "B" CAD system is inoperable.
During this time if "A" CAD system is inoperable, the reactor may remain in operation for a period of 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
III.
Add the following (note) to Table 3.2.F Any time during cycle 6 operation and prior to Unit 2 cycle 7 startup, LI-84-13A is not required if. CAD system "B" is inoperable.
JUSTIFICATION The design basis safety function of the CAD system is to prevent a combustible gas mixture from forming inside the containment after a loss of coolant accident (LOCA) by maintaining the oxygen concentration below 5 percent by volume.
This is done by injecting nitrogen gas into the containment from one of two redundant liquid nitrogen storage tanks and by venting the containment atmosphere through the standby gas treatment system.
The system is designed to supply nitrogen at a sufficient rate from either of the two systems to maintain the oxygen concentrations of both the drywell and suppression chamber atmospheres below 5 percent by volume based on the hydrogen and oxygen generation rates set forth in AEC Safety Guide 7.
The CAD system also provides backup pneumatic supply to, the drywell control air system primarily for the purpose of main steam relief valve operation for events beyond the design basis.
Each CAD system supplies approximately one half of the air operated components in the drywell.
This feature is also utilized in the safe shutdown analysis to meet the requirements of 10 CFR 50, Appendix R in which pneumatic pressure is required from both CAD systems.
These capabilities are not addressed in technical specifications and procedures allow for alternate methods (e.g., nitrogen bottles) or compensatory measures (i.e., fire watch after 7 days) for Appendix R.
When CAD system "B" is inoperable, appropriate actions will be taken to address the required alternate methods/compensatory measures.
CAD system "A" provides backup pneumatic supply to operate the torus to reactor building vacuum breakers.
This feature is not affected because the proposed change only allows CAD system "B" to be inoperable indefinitely.
Additional considerations include the ready availability of nitrogen through commercial means.
Typically, a nitrogen truck can be onsite in less than 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> in normal commercial transactions.
For urgent situations this time period is nominally less than 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
The BFH primary containment is maintained below 4 percent oxygen during normal operation in accordance with technical specification 3.7.A.5 using nitrogen gas from the containment inerting system.
Pathways which could introduce oxygen into the containment from outside are isolated during normal operation to preclude formation of a combustible mixture post accident.
Therefore, the only source of oxygen to form a combustible mixture with hydrogen gas after a
LOCA is generated within the containment from radiolytic decomposition of water.
This meets the three criteria given in the Generic Letter 84-09.
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..1 The BWR Mark I Owners Group undertook a substantial program in response to the addition of the provisions in 10 CFR 50.44(c) (3) requiring recombiner capability for those light water reactors that rely upon purge/repressurization systems as a primary means of hydrogen control.
This study and subsequent NRC Staff review demonstrated that the BMR Mark I plants affected by the recombiner rule (including BFN) do not need to rely on use of a safety grade purge/repressurization system required by 10 CFR 50.44(f) and (g) as a primary means of hydrogen control.
The study was submitted to NRC in General Electric NEDO 22155 and NRC review resulted in Generic Letter 84-09.
The study demonstrated that processes within the containment post accident are not capable of producing atmosphere greater than 5 percent oxygen by volume if the containment is inerted to within technical specification limits initially.
This study forms a basis for concluding that eliminating the redundancy of the CAD function will not affect the outcome of a design basis accident and will not affect risk to public health and safety.
This amendment also establishes a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> limiting condition for operation during which the plant may continue to operate without any CAD function.
The current technical specifications require immediate shutdown under the same circumstances.
NEDO 22155 and G.L. 84-09 establish that the CAD function will not be required after a design basis accident.
Therefore, maintenance of one fully capable CAD system with a 72 hour8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> L.C.O. is conservative with respect to the safety significant of the system.
Seventy-Two hours is a reasonable period of time to perform the necessary routine maintenance without causing an unnecessary plant shutdown.
It is made clear in Generic Letter 84-09 that NRC acceptance of NEDO 22155 does not affect the requirement of 10 CFR 50.44(f) and (g) to have a safety grade purge/repressurization system and that affected plants must continue to have that system.
However, it does form a regulatory and safety basis for temporary relief from requirements while the system is being repaired without requiring an unnecessary plant shutdown.
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ENCLOSURE 3
I DETERMINATION OF NO SIGNIFICANT HAZARDS CONSIDERATION BFN UNIT 2 DESCRIPTION OF PROPOSED AMENDMENT The proposed amendment would temporarily remove the requirement to have two independent containment air dilution (CAD) systems and modify the associated action statement to require a plant shutdown in 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> if the remaining single CAD system becomes inoperable.
It would also remove the requirement to have instrumentation to monitor the affected CAD system.
BASIS FOR DETERMINATIO OF NO SIGNIFICANT HAZARDS CONSIDERATION NRC has provided standards for determining whether a significant hazards consideration exists as stated in 10 CFR 50.92(C).
A proposed amendment to a operating license involves no significant hazards consideration if operation of the facility in accordance with the proposed amendment would not (1) involve a significant increase in the probability or consequences of a accident previously evaluated, or (2) create the possibility of a new or different kind of accident from an accident previously evaluated, or (3) involve a significant reduction in the margin of safety.
The proposed amendment will not affect the probability of occurrence of a previously analyzed accident.
The main function of the CAD system is to mitigate the effects of an accident by limiting the concentration of oxygen in the containment atmosphere after an accident has occurred.
The consequences of a accident are not significantly affected because the single train CAD system allowed by this change is not relied upon to mitigate an accident.
Conservative analysis has demonstrated that processes within the containment after an accident will not generate sufficient oxygen to produce a combustible mixture and the CAD function will not be needed.
2.'he proposed amendment does not create the possibility of a new or different kind of accident from any accident previously evaluated.
The CAD system is not a factor in normal plant operation and is mainly used after a postulated loss of coolant accident to control combustible gas inside the primary containment, as a backup pneumatic supply to the torus to reactor building vacuum breakers or to provide backup pneumatic supply to operate main steam relief valves during events beyond-design-basis.
The availability of the backup pneumatic supply is not addressed in technical specifications and not directly affected by the proposed amendment.
3 ~
The proposed amendment does not involve a significant reduction in a margin of safety.
The affected safety function of the CAD system to limit combustible gas mixture inside the primary containment is not relied upon during post accident.
The containment is inerted with nitrogen during normal operation and a more recent analysis documented in Generic Electric NEDO 22155 demonstrates that generation of oxygen within the containment after an accident is not sufficient to produce a
combustible mixture (greater than five percent).
DETERMINATION OF NO SIGNIFICANT HAZARDS CONSIDERATION Because the proposed amendment is encompassed.
by the criteria for which no significant hazards consideration exists, TVA has determined that the proposed amendment does not involve a significant hazards consideration.
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