GO2-23-107, Application to Revise Technical Specifications to Adopt TSTS-584, Eliminate Automatic RWCU System Isolation on SLC Initiation
| ML23339A124 | |
| Person / Time | |
|---|---|
| Site: | Columbia  |
| Issue date: | 12/05/2023 |
| From: | David Brown Energy Northwest |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| GO2-23-107 | |
| Download: ML23339A124 (1) | |
Text
ENERGY NORTHWEST December 5, 2023 GO2-23-107 David P. Brown Columbia Generating Station P.O. Box 968, PE23 Richland, WA 99352-0968 509.377.8385 dpbrown@energy-northwest.com 10 CFR 50.90 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001
Subject:
COLUMBIA GENERATING STATION, DOCKET NO. 50-397 APPLICATION TO REVISE TECHNICAL SPECIFICATIONS TO ADOPT TSTF-584, "ELIMINATE AUTOMATIC RWCU SYSTEM ISOLATION ON SLC INITIATION"
Dear Sir or Madam:
Pursuant to 10 CFR 50.90, Energy Northwest is submitting a request for an amendment to the Technical Specifications (TS) for Columbia Generating Station (Columbia).
Energy Northwest requests adoption of TSTF-584, "Eliminate Automatic RWCU System Isolation on SLC Initiation." TS 3.3.6.1, "Primary Containment Isolation Instrumentation," is revised to remove the requirement that the Reactor Water Cleanup (RWCU) System automatically isolate on manual initiation of the Standby Liquid Control (SLC) System. This change to the TS facilitates a future change to the plant design and procedures to require manually isolating the RWCU System when manually initiating the SLC System.
The enclosure provides a description and assessment of the proposed changes. provides the existing TS pages marked to show the proposed changes. provides revised (clean) TS pages. Attachment 3 provides the existing TS Bases pages marked to show revised text associated with the proposed TS changes and is provided for information only.
Energy Northwest requests that the amendment be reviewed under the Consolidated Line Item Improvement Process (CLIIP). Approval of the proposed amendment is requested within six months of acceptance. Once approved, the amendment shall be implemented within 90 days.
There are no regulatory commitments made in this submittal.
GO2-23-107 Page 2 of 2 In accordance with 10 CFR 50.91, Energy Northwest is notifying the State of Washington of this amendment request by transmitting a copy of this application, with attachments to the designated State Official.
If you should have any questions regarding this submittal, please contact Mr. R.M.
Garcia, Licensing Supervisor, at 509-377-8463.
I declare under penalty of perjury that the foregoing is true and correct.
Executed this 5th day of December, 2023.
Respectfully, David P. Brown Site Vice President
Enclosure:
Description and Assessment Attachments:
- 1. Proposed Technical Specification Changes (Mark-up)
- 2. Proposed Technical Specification Changes (Clean Pages)
- 3. Proposed Technical Specification Bases Markup Pages (For Information Only) cc:
NRC RIV Regional Administrator NRC NRR Project Manager NRC Senior Resident lnspector/988C CD Sonoda - BPA/1399 EFSEC@efsec.wa.gov - EFSEC E Fordham - WDOH R Brice - WDOH L Albin - WDOH
GO2-23-107 Enclosure Page 1 of 4
1.0 DESCRIPTION
DESCRIPTION AND ASSESSMENT Energy Northwest requests adoption of TSTF-584, "Eliminate Automatic RWCU System Isolation on SLC Initiation," into the Columbia Generating Station (Columbia) Technical Specification (TS). TS 3.3.6.1, "Primary Containment Isolation Instrumentation," is revised to remove the requirement that the Reactor Water Cleanup (RWCU) System automatically isolate on manual initiation of the Standby Liquid Control (SLC) System.
This change to the TS facilitates a future change to the plant design and procedures to require manually isolating the RWCU System when manually initiating the SLC System.
2.0 ASSESSMENT
2.1 Applicability of Safety Evaluation Energy Northwest has reviewed the safety evaluation for TSTF-584 provided to the Technical Specifications Task Force in a letter dated July 31, 2023. This review included a review of the Nuclear Regulatory Commission (NRC) staffs evaluation, as well as the information provided in TSTF-584. Energy Northwest has concluded that the justifications presented in TSTF-584 and the safety evaluation prepared by the NRC staff are applicable to Columbia and justify this amendment for the incorporation of the changes to the Columbia TS.
Energy Northwest confirms that the Columbia emergency operating procedures only credit manual initiation of the SLC System by the plant operators.
Energy Northwest confirms that the Columbia response to an Anticipated Transient Without Scram (A TWS) event that requires SLC System actuation would also result in automatic isolation of the RWCU System.
2.2 Optional Changes and Variations Energy Northwest is proposing the following variations from the TS changes described in TSTF-584 and the applicable parts of the NRC staff's safety evaluation:
Columbia TS utilize different numbering and titles than the Standard Technical Specifications on which TSTF-584 was based. Specifically, TSTF-584 removes from Table 3.3.6.1-1 FUNCTION 4.1, Standby Liquid Control System Initiation, where the Columbia TS would remove Table 3.3.6.1-1 FUNCTION 4.k, Standby Liquid Control (SLC) System Initiation. This difference is administrative and does not affect the applicability of TSTF-584 to the Columbia TS.
GO2-23-107 Enclosure Page 2 of 4
3.0 REGULATORY ANALYSIS
3.1 No Significant Hazards Consideration Analysis Energy Northwest requests adoption of TSTF-584, "Eliminate Automatic RWCU System Isolation on SLC Initiation," into the Columbia Technical Specification (TS). TS 3.3.6.1, "Primary Containment Isolation Instrumentation," is revised to remove the requirement that the Reactor Water Cleanup (RWCU) System automatically isolate on manual initiation of the Standby Liquid Control (SLC) System. The SLC System is manually actuated in response to an Anticipated Transient Without Scram (ATWS) event. This change to the TS facilitates a future change to the plant design and procedures to require manually isolating the RWCU System when manually initiating the SLC System.
Energy Northwest has evaluated if a significant hazards consideration is involved with the proposed amendment by focusing on the three standards set forth in 10 CFR 50.92, "Issuance of amendment," as discussed below:
- 1.
Does the proposed amendment involve a significant increase in the probability or consequences of an accident previously evaluated?
Response: No The proposed change eliminates the TS requirement that the RWCU System automatically isolate on manual initiation of the SLC System. The SLC System is manually initiated in response to an ATWS event. The TS function that requires isolation of the RWCU System on SLC initiation is not an initiator to an ATWS event.
Should an ATWS event occur and the SLC System be manually initiated per plant procedure, plant procedures may also direct isolation of the RWCU System from the control room. In addition, an ATWS event that requires SLC initiation will result in a lowering of reactor pressure vessel water level to the point that the RWCU System is automatically isolated (a function that will continue to be required by the TS.) As a result, removal of the RWCU System isolation on SLC initiation function from the TS will not result in an increase in the consequences of an A TWS event.
In addition to being used to mitigate an ATWS, the accident analysis credits manual actuation of the SLC System following a loss of coolant accident (LOCA) to control primary containment acidity. A LOCA will result in automatic isolation of the RWCU System by other TS-required functions. As a result, the proposed change will have no effect on the consequences of a LOCA.
Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.
GO2-23-107 Enclosure Page 3 of 4
- 2.
Does the proposed amendment create the possibility of a new or different kind of accident from any accident previously evaluated?
Response: No The proposed change eliminates the TS requirement that the RWCU System automatically isolate on manual initiation of the SLC System. The proposed change does not affect the design function of the RWCU System or the SLC System. The replacement of the automatic action to isolate the RWCU System on SLC initiation with manual action has the potential to introduce human error as a failure mechanism; however, in an ATWS event or LOCA, the RWCU System isolation would also be automatically initiated by low water level in the reactor pressure vessel. Consequently, no new failure mechanism is created, and no new or different kind of accident is created.
Therefore, the proposed change does not create the possibility of a new or different kind of accident from any accident previously evaluated.
- 3.
Does the proposed amendment involve a significant reduction in a margin of safety?
Response: No The proposed change eliminates the TS requirement that the RWCU System automatically isolate on manual initiation of the SLC System. The proposed change does not alter any controlling values of parameters established in the plant's licensing basis. The proposed change does not alter a design basis or safety limit (i.e., the controlling numerical value for a parameter established in the Updated Final Safety Analysis Report or the license). Consequently, the margin of safety is not significantly affected.
Therefore, the proposed change does not involve a significant reduction in a margin of safety.
Based on the above, Energy Northwest concludes that the proposed change presents no significant hazards consideration under the standards set forth in 10 CFR 50.92(c),
and, accordingly, a finding of "no significant hazards consideration" is justified.
3.2 Conclusion In conclusion, based on the considerations discussed above, (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendment will not be inimical to the common defense and security or to the health and safety of the public.
GO2-23-107 Enclosure Page 4 of 4 4.0 ENVIRONMENTAL EVALUATION A review has determined that the proposed amendment would change a requirement with respect to installation or use of a facility component located within the restricted area, as defined in 10 CFR 20, or would change an inspection or surveillance requirement. However, the proposed amendment does not involve (i) a significant hazards consideration, (ii) a significant change in the types or a significant increase in the amounts of any effluents that may be released offsite, or (iii) a significant increase in individual or cumulative occupational radiation exposure. Accordingly, the proposed amendment meets the eligibility criterion for categorical exclusion set forth in 10 CFR 51.22(c)(9). Therefore, pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the proposed amendment.
GO2-23-107 Proposed Technical Specification Changes (Mark-Up)
ACTIONS CONDITION H. Required Action and H.1 associated Completion Time of Condition F or G AND not met.
H.2 OR As required by Required Action C.1 and referenced in Table 3.3.6.1-1.
h Pcs Fe~l:liFea BY: Re~l:liFea
~
/\\etieR C.1 aRa FefeFeReea iR Taele a.a.6.1 1.
GR
~
1.J. As required by Required I.J.1 Action C.1 and referenced in Table 3.3.6.1-1.
SURVEILLANCE REQUIREMENTS Primary Containment Isolation Instrumentation 3.3.6.1 REQUIRED ACTION COMPLETION TIME Be in MODE 3.
12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> Be in MODE 4.
36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> geelaFe asseeiatea staRaey:
4--Aetlf li~1:1ia eeRtFSI (Sl::C) s1:1esy:stem iReperoele.
lselate tt=te ReaeteF lAfateF 4--Aetlf CleaRl:IP (RlAlGY) Sy:stem.
Initiate action to restore Immediately channel to OPERABLE status.
---NOTES---------------------
- 1.
Refer to Table 3.3.6.1-1 to determine which SRs apply for each Primary Containment Isolation Function.
- 2.
When a channel is placed in an inoperable status solely for performance of required Surveillances, entry into associated Conditions and Required Actions may be delayed for up to 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> provided the associated Function maintains isolation capability.
Columbia Generating Station 3.3.6.1-3 Amendment No. 449,4-e9~~294 2-7-G
Primary Containment Isolation Instrumentation 3.3.6.1 Table 3.3.6.1-1 (page 4 of 6)
Primary Containment Isolation Instrumentation APPLICABLE CONDITIONS MODES OR REQUIRED REFERENCED OTHER CHANNELS FROM SPECIFIED PER TRIP REQUIRED SURVEILLANCE ALLOWABLE FUNCTION CONDITIONS SYSTEM ACTION C.1 REQUIREMENTS VALUE
- 4.
RWCU System Isolation
- e.
Heat Exchanger 1, 2, 3 F
- 70°F Room Area SR 3.3.6.1.4 Ventilation SR 3.3.6.1.6 Differential Temperature - High
- f.
Pump Room Area 1, 2, 3 1 per room F
- 180°F Temperature - High SR 3.3.6.1.4 SR 3.3.6.1.6
- g.
Pump Room Area 1, 2, 3 1 per room F
- 100°F Ventilation SR 3.3.6.1.4 Differential SR 3.3.6.1.6 Temperature - High
- h.
RWCU/RCIC Line 1, 2, 3 F
- 180°F Routing Area SR 3.3.6.1.4 Temperature - High SR 3.3.6.1.6
- i.
RWCU Line Routing 1, 2, 3 1 per room F
SR 3.3.6.1.3 Area Temperature -
SR 3.3.6.1.4 SR 3.3.6.1.6 High Room 409, 509
- 175°F Areas Room 408, 511
- 180°F Areas
- j.
Reactor Vessel 1, 2, 3 2
~ -58 inches Water Level - Low SR 3.3.6.1.4 Low, Level 2 SR 3.3.6.1.6
~ StaAetey l::i~~iet
~
~et SR a.a.s.1.s GeAtFel (81::G)
SysteFA IAitiatieA kl.
Manual Initiation 1, 2, 3 2
G SR 3.3.6.1.6 NA (c)
Sl::G SysteFR IAitiatieA eAly iAJ:)~ts iAte eAe ef tl~e t1Ne tFiJ:) systeFRs. Deleted Columbia Generating Station 3.3.6.1-9 Amendment No. 4-e-1-,4-98 ~
~
~
~
Primary Containment Isolation Instrumentation 3.3.6.1 Table 3.3.6.1-1 (page 5 of 6)
Primary Containment Isolation Instrumentation APPLICABLE CONDITIONS MODES OR REQUIRED REFERENCED OTHER CHANNELS FROM SPECIFIED PER TRIP REQUIRED SURVEILLANCE ALLOWABLE FUNCTION CONDITIONS SYSTEM ACTION C.1 REQUIREMENTS VALUE
- 5.
Residual Heat Removal (RHR) Shutdown Cooling (SDC) System Isolation
- a.
Pump Room Area 3
1 per room F
SR 3.3.6.1.3 s 150°F Temperature - High SR 3.3.6.1.4 SR 3.3.6.1.6
- b.
Pump Room Area 3
1 per room F
SR 3.3.6.1.3 s 70°F Ventilation SR 3.3.6.1.4 Differential SR 3.3.6.1.6 Temperature - High C.
Heat Exchanger 3
1 per room F
SR 3.3.6.1.3 Area Temperature -
SR 3.3.6.1.4 High SR 3.3.6.1.6 Room 505 Area s 140°F Room 507 Area s 160°F Room 605 Area s 150°F Room 606 Area s 140°F
- d.
Reactor Vessel 3
2 IJ SR 3.3.6.1.1
~ 9.5 inches Water Level - Low, SR 3.3.6.1.2 Level 3 SR 3.3.6.1.4 SR 3.3.6.1.6
- e.
Reactor Vessel 1, 2, 3 F
SR 3.3.6.1.2 s 135 psig Pressure - High SR 3.3.6.1.4 SR 3.3.6.1.6
- f.
Manual Initiation 1, 2, 3 2
G SR 3.3.6.1.6 NA (d)
Deleted Columbia Generating Station 3.3.6.1-10 Amendment No.~,~~ 27G
GO2-23-107 Proposed Technical Specification Changes (Clean Pages)
ACTIONS CONDITION H. Required Action and H.1 associated Completion Time of Condition F or G AND not met.
H.2 OR As required by Required Action C.1 and referenced in Table 3.3.6.1-1.
I.
As required by Required 1.1 Action C.1 and referenced in Table 3.3.6.1-1.
SURVEILLANCE REQUIREMENTS Primary Containment Isolation Instrumentation 3.3.6.1 REQUIRED ACTION COMPLETION TIME Be in MODE 3.
12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> Be in MODE 4.
36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br /> Initiate action to restore Immediately channel to OPERABLE status.
--*---NOTES---------------------------
- 1.
Refer to Table 3.3.6.1-1 to determine which SRs apply for each Primary Containment Isolation Function.
- 2.
When a channel is placed in an inoperable status solely for performance of required Surveillances, entry into associated Conditions and Required Actions may be delayed for up to 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> provided the associated Function maintains isolation capability.
Columbia Generating Station 3.3.6.1-3 Amendment No. 449,4-eQ. ~
~
2e4 UO
A4F7BF Primary Containment Isolation Instrumentation 3.3.6.1 Table 3.3.6.1-1 (page 4 of 6)
Primary Containment Isolation Instrumentation APPLICABLE CONDITIONS MODES OR REQUIRED REFERENCED OTHER CHANNELS FROM SPECIFIED PER TRIP REQUIRED SURVEILLANCE ALLOWABLE FUNCTION CONDITIONS SYSTEM ACTION C.1 REQUIREMENTS VALUE
- 4.
RWCU System Isolation
- e.
Heat Exchanger 1, 2, 3 F
SR 3.3.6.1.3 s 70°F Room Area SR 3.3.6.1.4 Ventilation SR 3.3.6.1.6 Differential Temperature - High
- f.
Pump Room Area 1, 2, 3 1 per room F
SR 3.3.6.1.3 s 180°F Temperature - High SR 3.3.6.1.4 SR 3.3.6.1.6
- g.
Pump Room Area 1, 2, 3 1 per room F
SR 3.3.6.1.3 s 100°F Ventilation SR 3.3.6.1.4 Differential SR 3.3.6.1.6 Temperature - High
- h.
RWCU/RCIC Line 1, 2, 3 F
SR 3.3.6.1.3 s 180°F Routing Area SR 3.3.6.1.4 Temperature - High SR 3.3.6.1.6
- i.
RWCU Line Routing 1, 2, 3 1 per room F
SR 3.3.6.1.3 Area Temperature -
SR 3.3.6.1.4 High SR 3.3.6.1.6 Room 409, 509 s 175°F Areas Room 408, 511 s 180°F Areas
- j.
Reactor Vessel 1, 2, 3 2
F SR 3.3.6.1.2 2:'.: -58 inches Water Level - Low SR 3.3.6.1.4 Low, Level 2 SR 3.3.6.1.6
- k.
Manual Initiation 1, 2, 3 2
G SR 3.3.6.1.6 NA (c)
Deleted Columbia Generating Station 3.3.6.1-9 Amendment No. e4-,4-e9 ' ~
253 270
Primary Containment Isolation Instrumentation 3.3.6.1 Table 3.3.6.1-1 (page 5 of 6)
Primary Containment Isolation Instrumentation APPLICABLE CONDITIONS MODES OR REQUIRED REFERENCED OTHER CHANNELS FROM SPECIFIED PER TRIP REQUIRED SURVEILLANCE ALLOWABLE FUNCTION CONDITIONS SYSTEM ACTION C.1 REQUIREMENTS VALUE
- 5.
Residual Heat Removal (RHR) Shutdown Cooling (SOC) System Isolation
- a.
Pump Room Area 3
1 per room F
~ 150°F Temperature - High SR 3.3.6.1.4 SR 3.3.6.1.6
- b.
Pump Room Area 3
1 per room F
~ 70°F Ventilation SR 3.3.6.1.4 Differential SR 3.3.6.1.6 Temperature - High C.
Heat Exchanger 3
1 per room F
SR 3.3.6.1.3 Area Temperature -
SR 3.3.6.1.4 High SR 3.3.6.1.6 Room 505 Area
~ 140°F Room 507 Area
~ 160°F Room 605 Area
~ 150°F Room 606 Area
~ 140°F
- d.
Reactor Vessel 3
~ 9.5 inches Water Level - Low, SR 3.3.6.1.2 Level 3 SR 3.3.6.1.4 SR 3.3.6.1.6
- e.
Reactor Vessel 1, 2, 3 F
~ 135 psig Pressure - High SR 3.3.6.1.4 SR 3.3.6.1.6
- f.
Manual Initiation 1, 2, 3 2
G SR 3.3.6.1.6 NA (d)
Deleted Columbia Generating Station 3.3.6.1-10 Amendment No. ',' 225 270
GO2-23-107 Proposed Technical Specification Bases Markup Pages (For Information Only)
Primary Containment Isolation Instrumentation B 3.3.6.1 B 3.3 INSTRUMENTATION B 3.3.6.1 Primary Containment Isolation Instrumentation BASES BACKGROUND The primary containment isolation instrumentation automatically initiates closure of appropriate primary containment isolation valves (PCIVs). The function of the PCIVs, in combination with other accident mitigation systems, is to limit fission product release during and following postulated Design Basis Accidents (DBAs). Primary containment isolation within the time limits specified for those isolation valves designed to close automatically ensures that the release of radioactive material to the environment will be consistent with the assumptions used in the analyses for a OBA.
The isolation instrumentation includes the sensors, relays, and switches that are necessary to cause initiation of primary containment and reactor coolant pressure boundary (RCPB) isolation. Most channels include electronic equipment (e.g., trip relays) that compares measured input signals with pre-established setpoints. When the setpoint is exceeded, the channel outputs a primary containment isolation signal to the isolation logic. Functional diversity is provided by monitoring a wide range of independent parameters. The input parameters to the isolation logic are (a) reactor vessel water level, (b) area and differential temperatures, (c) main steam line (MSL) flow measurement, (d) Standby Liquid Control (SLG) System initiation, (de) condenser vacuum loss, (ef) main steam line pressure, (f§) reactor core isolation cooling (RCIC) steam line flow and time delay relay, (gh) ventilation exhaust plenum radiation, (h+) RCIC steam line pressure, (ij) RCIC turbine exhaust diaphragm pressure, Uk) reactor water cleanup (RWCU) differential and blowdown flows and time delay relay, (kt) reactor vessel pressure, and (Im) drywell pressure.
Redundant sensor input signals are provided from each such isolation initiation parameter. In addition, manual isolation of the logics is provided.
The primary containment isolation instrumentation has inputs to the trip logic from the isolation Functions listed below.
- 1. Main Steam Line Isolation Most Main Steam Line Isolation Functions receive inputs from four channels. The outputs from these channels are combined in one-out-of-two taken twice logic to initiate isolation of all main steam isolation valves (MSIVs). The outputs from the same channels are arranged into two two-out-of-two trip systems to isolate all MSL drain valves. One two-out-of-two trip system is associated with the inboard valve and the other two-out-of-two logic trip system is associated with the outboard valves.
Columbia Generating Station B 3.3.6.1-1 Revision +3
A4F7BF BASES Primary Containment Isolation Instrumentation B 3.3.
6.1 BACKGROUND
(continued)
Reactor Vessel Level - Low, Level 3 Function isolates the Group 5 valves.
Reactor Vessel Water Level - Low, Low, Level 2 Function isolates the Group 2, 3, and 4 valves. Drywell Pressure - High isolates the Group 3, 4, and 5 valves. Manual Initiation isolates the Group 2, 3, 4, and 5 valves. Reactor Building Vent Exhaust Plenum Radiation - High Function isolates the Group 3 valves.
- 3. Reactor Core Isolation Cooling System Isolation Most Functions receive input from two channels, with each channel in one trip system using one-out-of-one logic. One of the two trip systems is connected to the inboard valves and the other trip system is connected to the outboard valve on the RCIC penetration so that operation of either trip system isolates the penetration. The exceptions to this arrangement are the RCIC Steam Supply Pressure - Low and the RCIC Turbine Exhaust Diaphragm Pressure - High Functions. These Functions receive input from four steam supply pressure and four turbine exhaust diaphragm pressure channels, respectively. The outputs from these channels are connected into two-out-of-two trip systems, each trip system isolating the inboard or outboard RCIC valves. In addition, the RCIC System Isolation Manual Initiation Function has only one channel, which isolates the outboard RCIC valve only (provided an automatic initiation signal is present).
RCIC Isolation Functions isolate the Group 8 valves.
- 4. Reactor Water Cleanup System Isolation Most Functions receive input from two channels with each channel in one trip system using one-out-of-one logic. Functions 4.f and 4.g (Pump Room Area Temperature and Differential Temperature - High) have one channel in each trip system in each room for a total of four channels per Function, and Function 4.i (RWCU Line Routing Area Temperature -
High) has one channel in each trip system in each room for a total of eight channels per Function, but the logic is the same (one-out-of-one). Each of the two trip systems is connected to one of the two valves on the RWCU penetration so that operation of either trip system isolates the penetration. The exceptions to this arrangement are the Reactor Vessel Water Level - Low Low, Level 2, tt~e SLG System IRitiatieR, and the Manual Initiation Functions. The Reactor Vessel Water Level - Low Low, Level 2 Function receives input from four reactor vessel water level channels. The outputs from the reactor vessel water level channels are Columbia Generating Station B 3.3.6.1-3 Revision 443
BASES Primary Containment Isolation Instrumentation B 3.3.
6.1 BACKGROUND
(continued) connected into two-out-of-two trip systems, each trip system isolating one of the two RWCU valves. The SLG System Initiation Fu notion reeei:ves input from tv,10 ehannels (one from eaeh SLG pump). The outputs are eonneeted into a one out of t\\*;o trip system, with the trip system elosing only the outboard :valve. The Manual Initiation Function uses four channels, two per each switch and push button. Both channels from one switch and push button input into one trip system and both channels from the other switch and push button input into the other trip system, with the channels connected in a two-out-of-two logic. Each trip system isolates one of the two RWCU valves.
RWCU Isolation Functions isolate the Group 7 valves.
- 5. RHR Shutdown Cooling System Isolation Most Functions receive input from two channels with each channel in one trip system using one-out-of-one logic. Functions 5.a and 5.b (Pump Room Area Temperature and Pump Room Area Ventilation Differential Temperature - High) have one channel in each trip system in each room for a total of four channels per Function, and Function 5.c (Heat Exchanger Area Temperature - High) has one channel in each trip system in each room for a total of eight channels per Function, but the logic is the same (one-out-of-one). One of the two trip systems is connected to the outboard valves on each shutdown cooling penetration (reactor vessel head spray, shutdown cooling return, and shutdown cooling suction lines) and the other trip system is connected to the inboard valve on the shutdown cooling suction line penetration so that operation of either trip system isolates the penetrations. The exceptions to this arrangement are the Reactor Vessel Water Level - Low, Level 3 and the Manual Initiation Functions. The Reactor Vessel Water Level - Low, Level 3 Function receives input from four reactor vessel water level channels. The outputs from the reactor vessel water level channels are connected into two two-out-of-two trip systems, each trip system isolating the inboard or outboard valves. The Manual Initiation Function uses four channels, two per each switch and push button. Both channels from one switch and push button input into one trip system and both channels from the other switch and push button input into the other trip system, with the channels connected in a two-out-of-two logic. One trip system isolates the inboard valve and the other trip system isolates the outboard valves.
The RHR Shutdown Cooling Isolation Functions isolate the Group 6 valves.
Columbia Generating Station B 3.3.6.1-4 Revision 73
BASES Primary Containment Isolation Instrumentation B 3.3.6.1 APPLICABLE SAFETY ANALYSES, LCO, and APPLICABILITY (continued)
Reactor Vessel Water Level - Low Low, Level 2 signals are initiated from differential pressure transmitters with trip units that sense the difference between the pressure due to a constant column of water (reference leg) and the pressure due to the actual water level (variable leg) in the vessel.
Four channels of Reactor Vessel Water Level - Low Low, Level 2 Function are available and are required to be OPERABLE to ensure that no single instrument failure can preclude the isolation function.
The Reactor Vessel Water Level - Low Low, Level 2 Allowable Value was chosen to be the same as the ECCS Reactor Vessel Water Level - Low Low, Level 2 Allowable Value (LCO 3.3.5.1 ), since the capability to cool the fuel may be threatened.
This Function isolates the Group 7 valves.
4.k. SLC Systeffl Initiation The isolation of the RVVCU Systeffl is required v,<hen the SLC Systeffl has been initiated to pre11ent dilution and reffloval of the boron solution by the RWCU Systeffl (Ref. 8). SLC Systeffl initiation signals are initiated froffl the two SLC puFFlp start signals.
Two channels (one froffl each puFFlp) of SLC Systeffl Initiation Function are a¥ailable and are required to be OPERABLE in MODES 1 and 2, since these are the only MODES where the reactor can be critical. Both channels are also required to be OPERABLE in MODES 1, 2, and 3, since the SLC Systeffl is used to Fflaintain suppression pool pt=I at or above 7 following a LOCA to ensure iodine will be retained in the suppression pool 1,Yater. These MODES are oonsistent 1&'1ith the Applicability for the SLC Systeffl (LCO 3.1.7). Cofflpliance *with Reference 9 (Colufflbia Generating Station requires both SLG puFFlps be started to inject boron) ensures no single instrufflent failure can preclude the isolation function. As notes (footnote (e) to Table 3.a.e.1 1 ), this Function is only requires to elose the outboars Group 7 RVVCU isolation 1,al>1e since the signal only provisos input into one of the ti.vo tri13 systeffls.
There is no Allowable Value assoeiates with this Function sinee the ohannels are Ff!echanioally actuates based solely on the position of the SLC Systeffl initiation switch.
This Function isolates the GrouJ:) 7 val¥es.
Columbia Generating Station B 3.3.6.1-21 Revision +3
BASES Primary Containment Isolation Instrumentation B 3.3.6.1 APPLICABLE SAFETY ANALYSES, LCO, and APPLICABILITY (continued) 4.kl. Manual Initiation The Manual Initiation switch and push button channels introduce signals into the RWCU System isolation logic that are redundant to the automatic protective instrumentation and provide manual isolation capability. There is no specific FSAR safety analysis that takes credit for this Function. It is retained for overall redundancy and diversity of the isolation function as required by the NRG in the plant licensing basis.
There are two switch and push buttons (with two channels per switch and push button) for the logic, one switch and push button per trip system.
Four channels of the Manual Initiation Function are available and are required to be OPERABLE in MODES 1, 2, and 3 since these are the MODES in which the RWCU System Isolation automatic Functions are required to be OPERABLE.
There is no Allowable Value for this Function, since the channels are mechanically actuated based solely on the position of the switch and push buttons.
This Function isolates the Group 7 valves.
- 5. RHR Shutdown Cooling System Isolation 5.a, 5.b, 5.c. Area Temperature and Differential Temperature - High Area Temperature and Differential Temperature - High is provided to detect a leak from the associated system piping. The isolation occurs when a very small leak has occurred and is diverse to the high flow instrumentation. If the small leak is allowed to continue without isolation, offsite dose limits may be reached. These Functions are not assumed in any FSAR transient or accident analysis, since bounding analyses are performed for large breaks such as MSLBs.
Area Temperature - High signals are initiated from thermocouples that are located in the room that is being monitored. Two instruments for each Function monitor each area. Twelve channels for Area Temperature -
High Function are available and are required to be OPERABLE to ensure that no single instrument failure can preclude the isolation function.
There are four channels for the pump room areas (two per room) and eight channels for the heat exchanger areas (two per room).
Eight thermocouples provide input to the Differential Temperature - High Function. The output of these thermocouples is used to determine the differential temperature. Each channel consists of a differential Columbia Generating Station B 3.3.6.1-22 Revision +3
BASES
, Primary Containment Isolation Instrumentation B 3.3.6.1 ACTIONS (continued) both trip systems to have one channel OPERABLE or in trip. For Function 1.c, this would require both trip systems to have one channel, associated with each MSL, OPERABLE or in trip. For Functions 2.a, 2.b, 2.c, 2.d, 3.c, 3.d, 4.j, and 5.d, this would require one trip system to have two channels, each OPERABLE or in trip. For Functions 3.a, 3.b, 3.e, 3.f, 3.g, 4.a, 4.b, 4.c, 4.d, 4.e, 4.h, 4-k, and 5.e, this would require one trip system to have one channel OPERABLE or in trip. For Functions 4.f, 4.g, 4.i, 5.a, 5.b, and 5.c, each Function consists of channels that monitor several different locations. Therefore, this would require one channel per location to be OPERABLE or in trip (the channels are not required to be in the same trip system). The Condition does not include the Manual Initiation Functions (Functions 1.g, 2.e, 3.h, 4.kl, and 5.f), since they are not assumed in any accident or transient analysis. Thus, a total loss of manual initiation capability for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (as allowed by Required Action A.1) is allowed.
The channels in the trip system in the more degraded state should be placed in trip. The decision as to which trip system is in the more degraded state should be based on prudent judgment and current plant conditions (i.e., what MODE the plant is in).
The Completion Time is intended to allow the operator time to evaluate and repair any discovered inoperabilities. The Completion Time is acceptable because it minimizes risk while allowing time for restoration or tripping of channels.
Required Action C.1 directs entry into the appropriate Condition referenced in Table 3.3.6.1-1. The applicable Condition specified in Table 3.3.6.1-1 is Function and MODE or other specified condition dependent and may change as the Required Action of a previous Condition is completed. Each time an inoperable channel has not met any Required Action of Condition A or B and the associated Completion Time has expired, Condition C will be entered for that channel and provides for transfer to the appropriate subsequent Condition.
D.1, D.2.1, and D.2.2 If the channel is not restored to OPERABLE status or placed in trip within the allowed Completion Time, the associated MSLs may be isolated (Required Action D.1), and if allowed (i.e., plant safety analysis allows operation with an MSL isolated), plant operation with the MSL isolated may continue. Isolating the affected MSL accomplishes the safety function of the inoperable channel. This Required Action will generally Columbia Generating Station B 3.3.6.1-28 Revision -73
BASES Primary Containment Isolation Instrumentation B 3.3.6.1 ACTIONS (continued)
SURVEILLANCE REQUIREMENTS 1.1 and 1.2 If the ehannel is not restored to OPERABLE status within the allowed Completion Time, the assoeiated SLG subsystem is declared inoperable or the RVVCU System is isolated. Since this Function is reeiuired to ensure that the SLG System performs its intended function, sufficient remedial measures are provided by declaring the assoeiated SLG subsystem inoperable or isolating the R'NGU System.
The GomJ:)letion Time of 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> is aeeeptablc beeause it minimizes risl<
while allowing su#ieicnt time fer personnel to isolate the RWGU System.
If the channel is not restored to OPERABLE status or placed in trip within the allowed Completion Time, the associated penetration flow path should be closed. However, if the shutdown cooling function is needed to provide core cooling, these Required Actions allow the penetration flow path to remain unisolated provided action is immediately initiated to restore the channel to OPERABLE status. Actions must continue until the channel is restored to OPERABLE status.
As noted at the beginning of the SRs, the SRs for each Primary Containment Isolation Instrumentation Function are found in the SRs column of Table 3.3.6.1-1.
The Surveillances arc also modified by a Note to indicate that when a channel is placed in an inoperable status solely for performance of required Surveillances, entry into associated Conditions and Required Actions may be delayed for up to 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> provided the associated Function maintains isolation capability. Upon completion of the Surveillance, or expiration of the 6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> allowance, the channel must be returned to OPERABLE status or the applicable Condition entered and Required Actions taken. This Note is based on the reliability analysis (Refs. 10 and 11) assumption of the average time required to perform channel Surveillance. That analysis demonstrated that the 6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> testing allowance docs not significantly reduce the probability that the PCIVs will isolate the penetration flow path( s) when necessary.
Columbia Generating Station B 3.3.6.1-31 Revision 424