ML20302A218
| ML20302A218 | |
| Person / Time | |
|---|---|
| Site: | Technical Specifications Task Force |
| Issue date: | 10/27/2020 |
| From: | Michelle Honcharik Office of Nuclear Reactor Regulation |
| To: | Technical Specifications Task Force |
| Honcharik,M., NRR/DSS, 301-4151774 | |
| Shared Package | |
| ML20302A210 | List: |
| References | |
| BWROG-132, Rev. 0, TSTF-561-T, Rev. 0 | |
| Download: ML20302A218 (10) | |
Text
BWROG-132, Rev. 0 TSTF-561-T, Rev. 0 Technical Specifications Task Force Improved Standard Technical Specifications Change Traveler Bracket LCO 3.5.1 LCO Note in the ISTS NUREGs Affected: 1430 1431 1432 1433 1434 2194 Note: This "T" Traveler has been reviewed and approved by the Technical Specification Task Force and is made available as a template for plant-specific license amendments. This Traveler has not been reviewed and approved by the Nuclear Regulatory Commission. Any plant submitting a license amendment request to adopt this change should inform the industry contact listed below and copy the Technical Specification Task Force on their submittal letter.
Classification: 4) NUREG Only Change Recommended for CLIIP?: No Correction or Improvement: Correction NRC Fee Status:
Changes Marked on ISTS Rev 4.0 See attached.
Revision History OG Revision 0 Revision Status: Active Revision Proposed by: BWROG Revision
Description:
Original Issue Owners Group Review Information Date Originated by OG: 29-Mar-16 Owners Group Comments (No Comments)
Owners Group Resolution: Approved Date: 19-Apr-16 TSTF Review Information TSTF Received Date: 23-May-16 Date Distributed for Review 23-May-16 TSTF Comments:
(No Comments)
TSTF Resolution: Approved for Use Date: 20-Jul-16 Affected Technical Specifications LCO 3.5.1 ECCS - Operating LCO 3.5.1 Bases ECCS - Operating 20-Jul-16 Copyright(C) 2016, EXCEL Services Corporation. Use by EXCEL Services associates, utility clients, and the U.S. Nuclear Regulatory Commission is granted. All other use without written permission is prohibited.
TSTF-561, Rev. 0
- 1.
SUMMARY
DESCRIPTION The proposed change places brackets around the current Limiting Condition for Operation (LCO) 3.5.1 Note in the Boiling Water Reactor (BWR) Improved Standard Technical Specifications (ISTS). This proposed change to the ISTS clarifies that the Note allowing Low Pressure Coolant Injection (LPCI) subsystems to be operable during alignment and operation for decay heat removal is not applicable to all plants.
- 2. DETAILED DESCRIPTION 2.1 LPCI Description and Current Technical Specification Requirements LPCI is an independent operating mode of the RHR System. For many BWR/3 and /4 designs, there are two LPCI subsystems, each consisting of two motor driven pumps and piping and valves to transfer water from the suppression pool to the RPV via the corresponding recirculation loop. The LPCI subsystems are designed to provide core cooling at low RPV pressure. Upon receipt of an initiation signal, all four LPCI pumps are automatically started. RHR System valves in the LPCI flow path are automatically positioned to ensure the proper flow path for water from the suppression pool to the recirculation loops. When the RPV pressure drops sufficiently, the LPCI flow to the RPV, via the corresponding recirculation loop, begins. The water then enters the reactor through the jet pumps.
2.2. Current Technical Specifications Requirements LCO 3.5.1 provides the requirements for the Emergency Core Cooling System (ECCS) injection/spray subsystems and the Automatic Depressurization System (ADS). The LCO requires all LPCI subsystems to be operable. However, the LCO is modified by a Note that states: "Low pressure coolant injection (LPCI) subsystems may be considered OPERABLE during alignment and operation for decay heat removal with reactor steam dome pressure less than [the Residual Heat Removal (RHR) cut in permissive pressure]
in MODE 3, if capable of being manually realigned and not otherwise inoperable."
2.3. Reason for the Proposed Change It has been determined that some BWR plants, in particular BWR/3 and /4 plants with two LPCI subsystems, may not be able to realign the Residual Heat Removal (RHR) shutdown cooling system to the LPCI mode following a loss of coolant accident (LOCA) within the time period required to satisfy of the 10 CFR 50.46 acceptance criteria.
2.4 Description of the Proposed Change The proposed change adds brackets to the LCO 3.5.1 Note such that the Note will only be included in plant-specific TS if the realignment can be made in sufficient time for the system to perform its ECCS function as assumed in the accident analyses.
The proposed change only affects the ISTS.
Page 1
TSTF-561, Rev. 0 The Bases are revised to bracket the discussion of the note.
- 3. TECHNICAL EVALUATION This proposed change clarifies that the Note allowing LPCI subsystems to be operable during alignment and operation for decay heat removal may not be applicable to all BWR plants.
It has been determined that manually realigning an RHR shutdown cooling subsystem from shutdown cooling mode to LPCI mode could result in water flashing to steam in the RHR shutdown cooling piping, water hammer, or pressure locking or thermal binding of valves unless the RHR shutdown cooling piping is first allowed to cool (Reference 1).
The BWROG determined that BWR/3 and BWR/4 plants with two LCPI subsystems may not be able to realign from RHR shutdown cooling mode to LPCI mode following a loss of coolant accident (LOCA) within the time required to meet the 10 CFR 50.46 acceptance criteria. The BWR/3 and BWR/4 plants identified as having two LPCI subsystems that share components with RHR shutdown cooling are Monticello, Quad Cities, Fitzpatrick, Duane Arnold, Browns Ferry, Peach Bottom, Cooper, Fermi, Hatch, and Pilgrim.
The other BWR plants may be able to meet the LCO 3.5.1 and LCO 3.4.8 requirement simultaneously without using the LCO 3.5.1 Note. At least one licensee has received an NRC finding (Reference 2) for revising their operational procedures to prohibit using the note. The NRC position was the note should be removed if it cannot be used.
Another licensee received a Green non-cited violation (Reference 3). The NRC identified the possibility of RHR system flashing when transitioning in Mode 3 from shutdown cooling to LPCI. The issue was characterized as a potential violation of 10 CFR 50, Appendix B, Criterion III, Design Control, because the reviews performed in response to Generic Letter (GL) 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," did not identify this issue.
The Boiling Water Reactor Owner's Group (BWROG) formed an LPCI-Shutdown Cooling Alignment Ad Hoc Committee to evaluate the issue. Two documents were written:
NEDC-33792P Revision 0, "Evaluation of the Delay Time Impact of LPCI-SDC Re-alignment in Mode 3 Shutdown Cooling," December 2012, and LPCI-Shutdown Cooling Alignment Committee, "Position Paper - Guidance for Alignment and Venting of RHR Loop for Post-LOCA LPCI Mode Operation,"
December 2012.
In 2014, at the recommendation of the BWROG Licensing Committee, a second Ad Hoc committee was formed to evaluate the products created by the first Ad Hoc committee and recommend a strategy to resolve the conflict created by the Technical Specifications (TS) note. The Ad Hoc committee recommended that the LCO 3.5.1 Note be removed Page 2
TSTF-561, Rev. 0 and, if necessary, plants should enter the Action for an inoperable LCPI subsystem when it is aligned to RHR shutdown cooling in Mode 3 with reactor steam dome pressure less than the RHR cut in permissive pressure. This action has a 7 day completion time, which is much longer than the time typically required to transition to Mode 4 from Mode 3 at the RHR cut in permissive pressure.
Some BWRs have submitted a license amendment request (LAR) to remove the LCO 3.5.1 note, including Peach Bottom (NRC ADAMS Accession Number ML13339A780), that was approved July 28, 2014 (ADAMS Accession Number ML14163A589), and LaSalle (NRC ADAMS Accession Number ML15012A544). At least one BWR, Susquehanna, performed engineering evaluations and determined that the Note could be used and the necessary restrictions were added to operating procedures.
The Licensing Committee evaluated the above and determined that a generic Traveler justifying the removal of the LCO 3.5.1 Note should not be created because the change was not applicable to all BWRs, and the Traveler would need to discuss the differing plant configurations and licensing bases for the BWR plants. Further, licensees could use the LaSalle and Peach Bottom LARs as models to create a plant-specific TS change should it be needed. However, the Licensing Committee determined that the Note in the ISTS should be bracketed to indicate that it is plant-specific.
The Licensing Committee recommended that the BWROG members review their TS requirements and plant design to determine if the LCO 3.5.1 note can be used. If the note cannot be used, members should revise their TS to remove the note using the Peach Bottom or LaSalle LAR as a model.
- 4. REGULATORY EVALUATION This section is not required as this change only affects the ISTS.
- 5. REFERENCES
- 1. Sequoyah Nuclear Plant- NRC Integrated Inspection Report 05000327/2012002, 05000328/2012002 dated April 30, 2012.
- 2. Letter from M. Kunowski (U. S. Nuclear Regulatory Commission) to M. J.
Pacilio (Exelon Generation Company, LLC), "LaSalle County Station, Units 1 and 2 NRC Integrated Inspection Report 05000373/2012004; 05000374/2012004," dated October 30, 2012.
- 3. Quad Cities Nuclear Power Station, Units 1 And 2, Component Design Bases Inspection (CDBI) and Temporary Instruction 2515/177, Managing Gas Accumulation In Emergency Core Cooling, Decay Heat Removal, And Containment Spray Systems," Report 05000254/2011009; 05000265/2011009, dated December 5, 2011.
Page 3
TSTF-561, Rev. 0 Proposed Technical Specifications Changes
TSTF-561, Rev. 0 ECCS - Operating 3.5.1 3.5 EMERGENCY CORE COOLING SYSTEM (ECCS) AND REACTOR CORE ISOLATION COOLING SYSTEM (RCIC) 3.5.1 ECCS - Operating LCO 3.5.1 Each ECCS injection/spray subsystem and the Automatic Depressurization System (ADS) function of [seven] safety/relief valves shall be OPERABLE.
[ --------------------------------------------NOTE--------------------------------------------
Low pressure coolant injection (LPCI) subsystems may be considered OPERABLE during alignment and operation for decay heat removal with reactor steam dome pressure less than [the Residual Heat Removal (RHR) cut in permissive pressure] in MODE 3, if capable of being manually realigned and not otherwise inoperable.
]
APPLICABILITY: MODE 1, MODES 2 and 3, except high pressure coolant injection (HPCI) and ADS valves are not required to be OPERABLE with reactor steam dome pressure [150] psig.
ACTIONS
NOTE-----------------------------------------------------------
LCO 3.0.4.b is not applicable to HPCI.
CONDITION REQUIRED ACTION COMPLETION TIME A. One low pressure A.1 Restore low pressure 7 days ECCS injection/spray ECCS injection/spray subsystem inoperable. subsystem(s) to OPERABLE status.
OR One LPCI pump in both LPCI subsystems inoperable.
General Electric BWR/4 STS 3.5.1-1 Rev. 4.0
TSTF-561, Rev. 0 ECCS - Operating 3.5.1 BASES APPLICABLE SAFETY ANALYSES (continued)
This LCO helps to ensure that the following acceptance criteria for the ECCS, established by 10 CFR 50.46 (Ref. 10), will be met following a LOCA, assuming the worst case single active component failure in the ECCS:
- a. Maximum fuel element cladding temperature is 2200°F,
- b. Maximum cladding oxidation is 0.17 times the total cladding thickness before oxidation,
- c. Maximum hydrogen generation from a zirconium water reaction is 0.01 times the hypothetical amount that would be generated if all of the metal in the cladding surrounding the fuel, excluding the cladding surrounding the plenum volume, were to react,
- d. The core is maintained in a coolable geometry, and
- e. Adequate long term cooling capability is maintained.
The limiting single failures are discussed in Reference 11. For a large discharge pipe break LOCA, failure of the LPCI valve on the unbroken recirculation loop is considered the most severe failure. For a small break LOCA, HPCI failure is the most severe failure. One ADS valve failure is analyzed as a limiting single failure for events requiring ADS operation.
The remaining OPERABLE ECCS subsystems provide the capability to adequately cool the core and prevent excessive fuel damage.
The ECCS satisfy Criterion 3 of 10 CFR 50.36(c)(2)(ii).
LCO Each ECCS injection/spray subsystem and seven ADS valves are required to be OPERABLE. The ECCS injection/spray subsystems are defined as the two CS subsystems, the two LPCI subsystems, and one HPCI System. The low pressure ECCS injection/spray subsystems are defined as the two CS subsystems and the two LPCI subsystems.
With less than the required number of ECCS subsystems OPERABLE, the potential exists that during a limiting design basis LOCA concurrent with the worst case single failure, the limits specified in Reference 10 could be exceeded. All ECCS subsystems must therefore be OPERABLE to satisfy the single failure criterion required by Reference 10.
[ As noted, LPCI subsystems may be considered OPERABLE during alignment and operation for decay heat removal when below the actual RHR cut in permissive pressure in MODE 3, if capable of being manually General Electric BWR/4 STS B 3.5.1-4 Rev. 4.0
TSTF-561, Rev. 0 ECCS - Operating 3.5.1 BASES LCO (continued) realigned (remote or local) to the LPCI mode and not otherwise inoperable. Alignment and operation for decay heat removal includes when the required RHR pump is not operating or when the system is realigned from or to the RHR shutdown cooling mode. This allowance is necessary since the RHR System may be required to operate in the shutdown cooling mode to remove decay heat and sensible heat from the reactor. At these low pressures and decay heat levels, a reduced complement of ECCS subsystems should provide the required core cooling, thereby allowing operation of RHR shutdown cooling when necessary. ]
APPLICABILITY All ECCS subsystems are required to be OPERABLE during MODES 1, 2, and 3, when there is considerable energy in the reactor core and core cooling would be required to prevent fuel damage in the event of a break in the primary system piping. In MODES 2 and 3, when reactor steam dome pressure is 150 psig, ADS and HPCI are not required to be OPERABLE because the low pressure ECCS subsystems can provide sufficient flow below this pressure. ECCS requirements for MODES 4 and 5 are specified in LCO 3.5.2, "ECCS - Shutdown."
ACTIONS A Note prohibits the application of LCO 3.0.4.b to an inoperable HPCI subsystem 2. There is an increased risk associated with entering a MODE or other specified condition in the Applicability with an inoperable HPCI subsystem and the provisions of LCO 3.0.4.b, which allow entry into a MODE or other specified condition in the Applicability with the LCO not met after performance of a risk assessment addressing inoperable systems and components, should not be applied in this circumstance.
A.1 If any one low pressure ECCS injection/spray subsystem is inoperable, or if one LPCI pump in both LPCI subsystems is inoperable, the inoperable subsystem(s) must be restored to OPERABLE status within 7 days. In this Condition, the remaining OPERABLE subsystems provide adequate core cooling during a LOCA. However, overall ECCS reliability is reduced, because a single failure in one of the remaining OPERABLE subsystems, concurrent with a LOCA, may result in the ECCS not being able to perform its intended safety function. The 7 day Completion Time is based on a reliability study (Ref. 12) that evaluated the impact on ECCS availability, assuming various components and subsystems were taken out of service. The results were used to calculate the average availability of ECCS equipment needed to mitigate the consequences of a LOCA as a function of allowed outage times (i.e., Completion Times).
General Electric BWR/4 STS B 3.5.1-5 Rev. 4.0
TSTF-561, Rev. 0 ECCS - Operating 3.5.1 3.5 EMERGENCY CORE COOLING SYSTEMS (ECCS) AND REACTOR CORE ISOLATION COOLING SYSTEM (RCIC) 3.5.1 ECCS - Operating LCO 3.5.1 Each ECCS injection/spray subsystem and the Automatic Depressurization System (ADS) function of [eight] safety/relief valves shall be OPERABLE.
[ -------------------------------------------NOTE--------------------------------------------
Low pressure coolant injection (LPCI) subsystems may be considered OPERABLE during alignment and operation for decay heat removal with reactor steam dome pressure less than [the residual heat removal cut in permissive pressure] in MODE 3, if capable of being manually realigned and not otherwise inoperable.
]
APPLICABILITY: MODE 1, MODES 2 and 3, except ADS valves are not required to be OPERABLE with reactor steam dome pressure [150] psig.
ACTIONS
NOTE-----------------------------------------------------------
LCO 3.0.4.b is not applicable to HPCS.
CONDITION REQUIRED ACTION COMPLETION TIME A. One low pressure A.1 Restore low pressure 7 days ECCS injection/spray ECCS injection/spray subsystem inoperable. subsystem to OPERABLE status.
B. High Pressure Core B.1 Verify by administrative Immediately Spray (HPCS) System means RCIC System is inoperable. OPERABLE when RCIC is required to be OPERABLE.
AND B.2 Restore HPCS System to 14 days OPERABLE status.
General Electric BWR/6 STS 3.5.1-1 Rev. 4.0
TSTF-561, Rev. 0 ECCS - Operating B 3.5.1 BASES APPLICABLE SAFETY ANALYSES (continued)
The limiting single failures are discussed in Reference 11. For a large break LOCA, failure of ECCS subsystems in Division 1 (LPCS and LPCI-A) or Division 2 (LPCI-B and LPCI-C) due to failure of its associated diesel generator is, in general, the most severe failure. For a small break LOCA, HPCS System failure is the most severe failure. One ADS valve failure is analyzed as a limiting single failure for events requiring ADS operation. The remaining OPERABLE ECCS subsystems provide the capability to adequately cool the core and prevent excessive fuel damage.
The ECCS satisfy Criterion 3 of 10 CFR 50.36(c)(2)(ii).
LCO Each ECCS injection/spray subsystem and eight ADS valves are required to be OPERABLE. The ECCS injection/spray subsystems are defined as the three LPCI subsystems, the LPCS System, and the HPCS System.
The low pressure ECCS injection/spray subsystems are defined as the LPCS System and the three LPCI subsystems.
With less than the required number of ECCS subsystems OPERABLE during a limiting design basis LOCA concurrent with the worst case single failure, the limits specified in 10 CFR 50.46 (Ref. 10) could potentially be exceeded. All ECCS subsystems must therefore be OPERABLE to satisfy the single failure criterion required by 10 CFR 50.46 (Ref. 10).
[ As noted, LPCI subsystems may be considered OPERABLE during alignment and operation for decay heat removal when below the actual RHR cut in permissive pressure in MODE 3, if capable of being manually realigned (remote or local) to the LPCI mode and not otherwise inoperable. Alignment and operation for decay heat removal includes when the required RHR pump is not operating or when the system is realigned from or to the RHR shutdown cooling mode. This allowance is necessary since the RHR System may be required to operate in the shutdown cooling mode to remove decay heat and sensible heat from the reactor. At these low pressures and decay heat levels, a reduced complement of ECCS subsystems should provide the required core cooling, thereby allowing operation of RHR shutdown cooling when necessary. ]
APPLICABILITY All ECCS subsystems are required to be OPERABLE during MODES 1, 2, and 3 when there is considerable energy in the reactor core and core cooling would be required to prevent fuel damage in the event of a break in the primary system piping. In MODES 2 and 3, the ADS function is not required when pressure is 150 psig because the low pressure ECCS subsystems (LPCS and LPCI) are capable of providing flow into the RPV below this pressure. ECCS requirements for MODES 4 and 5 are specified in LCO 3.5.2, "ECCS - Shutdown."
General Electric BWR/6 STS B 3.5.1-4 Rev. 4.0