ML18036B110
| ML18036B110 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 12/23/1992 |
| From: | TENNESSEE VALLEY AUTHORITY |
| To: | |
| Shared Package | |
| ML18036B109 | List: |
| References | |
| TVA-BFN-TS-329, NUDOCS 9212300131 | |
| Download: ML18036B110 (20) | |
Text
PROPOSED TECHNICAL SPECZFZCATZON CHANGE BROWS FERRY NUCLEAR PLANT UNIT 2 (TVA BFN TECHNICAL SPECIFICATION NO. 329) 92i230oi3i OOPg0 PDR ADOCK o o Pg P
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TABLE 3.2.A (Continued)
PRIHARY CONTAINHENT AND REACTOR BUILDING ISOLATION INSTRUHENTATION Hinimum No.
P a Instrument Channel s Operabl e Per Tri Ss 1
11 0
I P
Function Instrument Channel Reactor Water Cleanup System Hain Steam Valve Vault (TIS-069-834A-D)
Instrument Channel Reactor Water Cleanup System Pipe Trench (TIS-069-835A-D)
Instrument Channel Reactor Water Cleanup System Pump Room 2A (TIS-069-836A-D)
Instrument Channel Reactor Water Cleanup System Pump Room 28 (TIS-069-837A-D)
Instrument Channel Reactor Water Cleanup System Heat Exchanger Room (TIS-069-838A-0)
Instrument Channel Reactor Water Cleanup System Heat Exchanger Room (TIS-069-839A-0)
Tri Level Settin
< 201.0'F
< 135.0~F
< 152.00F
< 152.0'F
< 143.0'F
< 170
Action 1
Remarks Above Trip Setting initiates Isolation of Reactor Mater Cleanup Lines to and from the Reactor Above Trip Setting initiates Isol ation of Reactor Mater Cleanup Lines to and from the Reactor Above Trip Setting initiates Isolation of Reactor Water Cleanup Lines to and from the Reactor Above Trip Setting initiates Isolation of Reactor Water Cleanup Lines to and from the Reactor Above Trip Setting initiates Isolation of Reactor Water Cleanup Lines to and from the Reactor Above Trip Set ting initiates Isol ation of Reactor Water Cleanup Lines to and from the Reactor
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TABLE 4.2.A (Cont'd)
SURVEILLANCE RE(UIREHENTS FOR PRIHARY CONTAINHENT AND REACTOR BUILDING ISOLATION INSTRUHENTATION Function Fun tional Test Calibration Fre u n Instrum nt heck Group 1 (Initiating) Logic Group 1 (Actuation) Logic Checked during channel N/A functional test.
No further test required.(ll)
Once/operating cycle (21)
N/A N/A N/A Group 2 (Initiating) Logic Group 2
(RHR Isolation-Actuation)
Logic Group 8 (Tip-Actuati on) Logi c Group 2 (Drywell Sump Drains-Actuation) Logic Group 2 (Reactor Building and Refueling floor, and Drywell Vent and Purge-Actuation)
Logic Group 3 (Initiating) Logic Group 3 (Actuation) Logic Group 6 Logic Checked during channel N/A functional test.
No further test required.
Once/operating cycle (21)
N/A Once/operating cycle (21)
N/A Checked during channel N/A functional test.
No further test required.
Once/operating cycl e (21)
N/A Once/operating cycle (18)
N/A Once/operating cycl e (21)
N/A Once/operating cycl e (21)
N/A N/A N/A N/A N/A N/A N/A N/A N/A Group 8 (Initiating) Logic Checked during channel functional test.
No further test required.
N/A N/A Reactor Building Isolation (refueling floor) Logic Once/6 months (18)
(6)
N/A Reactor Building Isolation (reactor zone)
Logic Once/6 months (18)
(6)
N/A
l1 P
TABLE 4.2.A (Cont'd)
SURVEILUNCE RE(}UIREHENTS FOR PRIHARY CONTAINHENT AND REACTOR BUILDING ISOLATION INSTRUHENTATION Function SGTS Train A Logic SGTS Train 8 Logic SGTS Train C Logic Instrument Channel-Reactor Water Cleanup System Hain Steam Valve Vault (TIS-069-834A-D)
Instrument Channel Reactor Water Cleanup System Pipe Trench (TIS-069-835A-D)
Instrument Channel-Reactor Water Cleanup System Pump Room 2A (TIS&69-836A-D)
Instrument Channel Reactor Water Cleanup System Pump Room 2B (TIS-069-837A-D)
Instrument Channel Reactor Water Cleanup System Heat Exchanger Room (TIS-069-838A-0)
Instrument Channel Reactor Water Cleanup System Heat Exchanger Room (TIS-069-839A-D)
Functional Test Once/6 months (19)
Once/6 months (19)
Once/6 months (19)
(1) (27)
(1) (27)
(l)(27)
(l)(27)
(1) (27)
(1) (27)
Calibration Fre uenc N/A N/A N/A 4 months 4 months 4 months 4 months 4 months 4 months In trument Che k
N/A N/A N/A N/A N/A N/A N/A N/A N/A
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in the system, isolation is provided by high temperature in the cleanup system area.
Also, since the vessel could potentially be drained through the cleanup
- system, a low-level isolation is provided.
the consequences of an accident which results in the isolation of other process lines.
The signals which initiate isolation of Groups 4 and 5 process lines are therefore indicative of a condition which would render them inoperable.
~Grou Lines are connected to the primary containment but not directly to the reactor vessel.
These valves are isolated on reactor low water level (538"), high drywell pressure, or reactor building ventilation high radiation which would indicate a possible accident and necessitate primary containment isolation.
~Grou (Deleted)
~Grou 8 Line (traveling in-core probe) is isolated on high drywall pressure
- ,.- or reactor low-water level (538").
This is to assure that this line does not provide a leakage path when containment pressure or reactor water level indicates a possible accident condition.
The maximum closure time for the automatic isolation valves of the primary containment and reactor vessel isolation control system have been selected in consideration of the design intent to prevent core uncovering following pipe breaks outside the primary containment and the need to contain released fission products following pipe breaks inside the primary containment.
In satisfying. this design intent,.an additional margin has been. included in
. specifying maximum closure times.
This margin permits identification of degraded valve. performance, prior.,to exceeding, the design closure times.
In order to assure that the doses that may result from a steam line break do not exceed the 10 CFR 100 guidelines, it is necessary that no fuel rod perforation resulting from the accident occur prior to closure of the main steam line isolation valves.
Analyses indicate that fuel rod cladding perforations would be avoided for main steam valve closure times, including instrument delay, as long as 10.5 seconds.
BFN Unit 2 3.7/4.7-45
ENCLOSURE 2
BROWNS FERRY NUCLEAR PLANT (BFN)
UNIT 2 (TVA BFN TECHNICAL SPECIFICATION NO 329)
REASON FOR THE CHANGE DESCRIPTION AND iYUSTIFICATION REASON FOR THE CHANGE The Reactor Water Cleanup (RWCU) system for Unit 2 is presently configured such that the pumps take suction directly from the reactor vessel and recirculation loop A.
At rated reactor pressure vessel temperature and
- pressure, the RWCU pumps are processing approximately 500'F water which causes pump vibration and seal leakage problems.
A design change to the RWCU system will be worked for Unit 2 during the upcoming refueling outage that will reroute the RWCU pump suction to downstream of the non-regenerative heat exchanger.
This reroute will reduce the inlet water temperature to the RWCU pumps to approximately 120 F.
A High Energy Line Break (HELB) analysis was performed in conjunction with the design change.
As a result, temperature switches are being added in the pipe chase area of the RWCU heat exchanger room for BFN Unit 2.
DESCRIPTION OF THE PROPOSED CHANGE The followin chan es are ro osed for Unit 2:
1.
Add the following isolation instrumentation to Table 3.2.A, page 3.2/4.2-11a:
Minimis Ho.
Instrwent Channels Operable Per Tri S s 1
11 Function tri Level Oottin
~ection i
Remarks Instrwent Channel Reactor Water Cleanup System Heat Exchanger Room (TIS-069-839A-D)
< 170.0'F C
Above Trip Setting initiates isolation of Reactor Water Cleanup Lines to and from the Reactor 2.
Add the following isolation instrumentation to Table 4.2.A, page 3.2/4.2-43:
Function Functional Test Calibration Fr uenc Instrunent Check Instrunent Channel-Reactor Water Cleanup System Heat Exchanger Room (TIS-069-839A-0)
(1)(27) 4 months HIA (Note:
Page 3.2/4.2-42 is included in the amendment package because the addition of the above change on page 3.2/4.2-43 requires shifting of present provisions on that page.
There are no changes to TS requirements on Page 3.2/4.2-42.)
4
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ENCLOSURE 2
(CONTINUED) 2 of 3 BROWNS FERRY NUCLEAR PLANT '(BFN)
UNIT 2 (TVA BFN TECHNICAL SPECIFICATION NO 329)
REASON FOR THE CHANGE DESCRIPTION AND JUSTIFICATION DESCRIPTION OF THE PROPOSED CHANGE (continued) 3.
Present.
Bases 3.7.D/4.7.D for the Group 3 valve description reads in part as follows:
"To protect the reactor from a possible pipe break in the system, isolation is provided by high temperature in the cleanup system area or high drain temperature."
The proposed change to Bases 3.7.D/4.7.D reads as follows:
"To protect the reactor from a possible pipe break in the system, isolation is provided by high temperature in the cleanup system area."
aMSTIFICATION FOR THE PROPOSED CHANGE The RWCU System does not have a safety function beyond the maintenance of the reactor coolant pressure boundary and the primary/secondary containment boundary.
It maintains high reactor-water purity to limit chemical and corrosive action, thereby limiting fouling and deposition on heat transfer surfaces.
The system is designed to automatically isolate following detection of high temperatures in the areas surrounding the RWCU piping and following low reactor vessel water level, since these conditions may be associated with a
The automatic closure of the RWCU System isolation valves prevents excessive loss of reactor coolant and the release of significant amounts of radioactive material from the nuclear system process barrier into the Reactor Building.
In response to RWCU Pump vibration and seal leakage problems associated with high temperature process fluid and consequential
- stresses, a
RWCU System piping reroute will provide the pumps with cooler suction water.
The reroute will place the RWCU pump suction downstream of the non-regenerative heat exchangers where water temperature is approximately 120'F during normal operation.
This design change was coordinated with programs to reduce intergranular stress corrosion cracking.
During the design process for the RWCU changes, a Reactor Building HELB analysis was performed to look at the new system configuration.
This analysis indicated the need for temperature switches in the main steam valve vault, the heat exchanger room and the RWCU pipe trench.
As a result, temperature switches are being added in the pipe chase area of the RWCU Heat Exchanger Room for Unit 2.
The presently installed temperature switches in the RWCU pump rooms are also being retained.
The Unit 2 piping modifications will increase the pipe size running from the reactor vessel to the regenerative heat exchanger from 4 inches to 6 inches.
The HELB an'alysis determined that the fluid blowdown rate from a 6-inch pipe break near containment isolation valve 2-FCV-69-2 is more severe for the rerouted configuration than for the original configuration.
This analysis
> ~
ENCLOSURE 2
(CONTINUED) 3 of 3 BROGANS FERRY NUCLEAR PLANT (BFN)
UNIT 2 (TVA BFN TECHNICAL SPECIFICATION NO+ 329)
REASON FOR THE CHANGE DESCRIPTION AND JUSTIFICATION JUSTIFICATION FOR THE PROPOSED CHANGE (continued) necessitates additional temperature switches in that compartment of the RWCU Heat Exchanger Room to detect and initiate isolation of the break.
The additional switches detect the pipe break early enough to commence closure of primary containment isolation valves 2-FCV-69-1 and 2-FCV-69-2, as well as 2-FCV-69-12, in order to maintain the required environmental parameters inside the Unit 2 reactor building.
The new temperature detection loops consisting of resistance temperature detectors (RTDs) and analog trip units (ATUs) are qualified for the environment where they will operate.
The four temperature switches being added to the Unit 2 RWCU Heat Exchanger Room will perform the same function as the existing Unit 2 RWCU leak detection temperature switches.
Including these devices in the technical specifications will help to ensure that they are periodically tested in accordance with the plant surveillance testing program.
The minimum number of instrument channels required to be operable per trip system of two, matches the same requirement for existing instrumentation.
The proposed Action requirements also match those of existing instrumentation.
The four new temperature switches will be channelized the same as presently installed switches by designating two channels as Division I and two channels as Division II to ensure physical, electrical, and functional independence.
The trip logic for the new switches requires one trip from Division I and one from Division II (one out of two taken twice) in order to initiate a primary containment isolation signal to RWCU primary containment isolation valves 2-FCV-069-1 and 2-FCV-069-2, as well as 2-FCV-069-12.
Because of this logic arrangement, the failure of a single RTD, ATU, or power feed will not prevent isolation and will minimize spurious isolations.
The setpoints for the new temperature loops were selected high enough to ensure that spurious trips are not received during normal operation and low enough to provide timely detection of a RWCU system line break.
This improves the detection/isolation of RWCU breaks and helps to limit the reactor coolant lostg helps assure core cooling, and helps to ensure environmental conditions inside the reactor building are maintained within the limits stated on environmental drawings.
The revision to Table 3.2.A gives the allowable value for each function.
Trip settings have been chosen and will be established in plant instructions to ensure that the allowable values are not exceeded taking into account instrument drift and inaccuracies.
The change to Unit 2 Bases 3.7.D/4.7.D deletes the RWCU high drain temperature from the description of Group 3 valve isolation signals.
This change for the Unit 2 TS reflects the deletion of the drain temperature detection instrumentation from Tables 3.2.A and 4.2.A which was approved by the NRC in Amendment 189, dated February 6,
1991.
ENCLOSURE 3
BROWNS FERRY NUCLEAR PLANT (BFN)
UNIT 2 (TVA BFN TECHNICAL SPECIFICATION NO>> 329)
PROPOSED NO SIGNIFICANT HAZARDS CONSIDERATIONS DETERMINATION DESCRIPTION OF THE PROPOSED TECHNICAL SPECIFICATION CHANGE The technical specifications for BFN Unit 2 are bei.ng revised to reflect design changes in the reactor water cleanup (RWCU) system and a new High Energy Line Break (HELB) analysis.
Addi.ti.onal temperature detection loops are being added to Unit 2 TS Tables 3.2.A and 4.2.A.
BASES FOR PROPOSED NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION NRC has provided standards for determining whether a signi.ficant hazards consideration exists as stated in 10 CFR 50.91(c).
A proposed amendment to an operating license involves no significant hazards considerations if operation of the facility in accordance with the proposed amendment would not (1) involve a significant increase in the probability or consequences of an 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 a margin of safety.
The proposed TS change is judged to involve no significant hazards considerations based on the following:
1.
The proposed amendment does not involve a significant increase i.n the probability or consequences of any accident previ.ously evaluated.
As a result of a desi.gn change to be performed for the RWCU system, a HELB analysis was performed for the reactor building which identified certain RWCU pipe breaks which could not be automatically detected and isolated in a reasonable time frame.
To resolve this issue, qualified temperature detection loops are being added to the RWCU heat exchanger room.
These new temperature detection loops consist of environmentally qualified RTDs and IEEE Class 1E qualified ATUs located to detect and isolate criti.cal RWCU pipe breaks.
The safety function of the RTD/ATU temperature loops is to provide an isolation signal to close the RWCU suction line isolation valves (FCV 001 and FCV-69-002) and RWCU return line valve (FCV-69-012) on a high area temperature.
This ensures RWCU pipe breaks are i.solated.
No other RWCU safety functions are affected by the change.
Components added by this change are qualified for the environment in which they will operate.
This ensures that the system will perform its function in a post accident environment.
No additional paths for the release of radiation or contamination are created.
The failure modes of the RTDs and ATUs are such that any single failure will result in a gross failure alarm and/or a channel trip.
Because of the redundancy, separations, and logic designed into the system, a single failure of any part of the system will not prevent i.solation of the primary containment i.solation valves and spurious operation is minimized.
The RTDs will be located and the instrument setpoints will be set to preclude spurious trips due to ambient
4A >
ENCLOSURE 3
(CONTINUED)
Page 2 of 3 BROWNS FERRY NUCLEAR PLANT (BFN)
UNIT 2 (TVA BFN TECHNICAL SPECIFICATION NO. 329)
REASON FOR THE CHANGE DESCRIPTION AND a7USTIFICATION BASES FOR PROPOSED NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION (continued) temperatures including localized hot areas while assuring a timely trip due to a pipe break.
Therefore, the proposed amendment does not involve a significant increase in the probability or consequences of any accident previously evaluated.
2.
The proposed amendment does not create the possibility of a new or different kind of accident from any accident previously evaluated.
This change is being made to improve the RWCU leak detection/isolation function of the RWCU Primary Containment Isolation System (PCIS).
The PCIS will perform its intended safety function in the same manner as the previous installation.
There is no affect on the function or operation of any other plant system.
Failure of the new RTD/ATU temperature loops would be no different than failure of existing temperature switches.
Since environmental qualification requirements, divisional separation, single failure requirements and one-out-of-two taken twice logic requirements are maintained, the possibility of a RWCU isolation failure on a RWCU line break or of a spurious isolation is no more likely after the change than before.
In the existing design, logic relays are powered from RPS Bus A or B.
The new design also uses RPS Bus A or B to feed the ATUa.
Therefore, the consequence of a power failure is unchanged from the present design.
The seismic qualification and proper circuit coordination of the installation is maintained.
The system functions and operates in the same manner as previously evaluated in the Safety Analysis Report.
No new system interactions other than additional RTDs located in the heat exchanger room to input into the PCIS logic for isolation of the RWCU have been introduced by this activity.
Therefore, the proposed amendment does not create the possibility of a new or different kind of accident from any accident previously evaluated.
3.
The proposed amendment does not involve a significant reduction in the margin of safety.
The margin of safety will be enhanced by installing instruments that provide quicker response to a temperature rise indicative of a pipe break.
Calculations have been performed to determine the analytical limits for the RTD/ATU temperature loops in each of the monitored areas and to determine the setpoints for the ATUs in each area.
The setpoints are set above the maximum expected room temperatures to avoid spurious actuations due to ambient conditions and below the analytical limits to ensure timely detection of a pipe break.
This type of design utilizing ATUs has been analyzed by the NRC (NED0-21617, Analog Transmitter/Trip Unit System for Engineered Safeguard Sensor Trip Input) and has been found to be
ENCLOSURE 3
(CONTINUED)
Page 3 of 3 BROljtNS FERRY NUCLEAR PLANT (BFN)
UNIT 2 (TVA BFN TECHNICAL SPECIFICATION NO 329)
REASON FOR THE CHANGE DESCRXPTXON AND a7USTIFICATION BASES FOR PROPOSED NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION (continued) generically acceptable at BWR facilities.
Therefore, the proposed amendment does not involve a significant reduction in any margin of safety.
CONCLUSION TVA has evaluated the proposed amendment described above against the criteria given in 10 CFR 50.92(c) in accordance with the requirements of 10 CFR 50.91(a)(1).
This evaluation has determined that the proposed amendment will not (1) involve a significant increase in the probability or consequences of an accident previously evaluated, (2) create the possibility for a new or different kind of accident from any accident previously evaluated, or (3) involve a significant reduction in a margin of safety.
- Thus, TVA has concluded that the propo'sed amendment does not involve a significant hazards consideration.