L-23-207, License Amendment Request (LAR) for Adoption of TSTF-264-A Revision 0, 3.3.9 and 3.3.10 - Delete Flux Monitors Specific Overlap Requirement SRs
ML24025A011 | |
Person / Time | |
---|---|
Site: | Perry |
Issue date: | 01/24/2024 |
From: | Penfield R Energy Harbor Nuclear Corp |
To: | Office of Nuclear Reactor Regulation, Document Control Desk |
References | |
L-23-207 | |
Download: ML24025A011 (1) | |
Text
m energy Energy Harbor Nuclear Corp.
Perry Nuclear Power Plant 10 Center Road
~ harbor Perry, Ohio 44081
Rod L. Penfield 440-280-5382 Site Vice President, Perry Nuclear
January 24, 2024 L-23-207 10 CFR 50.90
ATTN: Document Control Desk U.S. Nuclear Regulatory Commission Washington, DC 20555-0001
Subject:
Perry Nuclear Power Plant, Unit No. 1 Docket No. 50-440, License No. NPF-58 License Amendment Request {LAR) for Adoption of TSTF-264-A Revision 0, "3.3.9 and 3.3.10 - Delete Flux Monitors Specific Overlap Requirement SRs"
Pursuant to 10 CFR 50.90, Energy Harbor Nuclear Corp. is submitting a request for amendment to the Perry Nuclear Power Plant, Unit 1 (PNPP) Technical Specification (TS) 3.3.1.1, "Reactor Protection System (RPS) Instrumentation." The proposed change would adopt Technical Specifications Task Force (TSTF) traveler TSTF-264-A, Revision 0, and delete surveillance requirements (SRs), 3.3.1.1.6 and 3.3.1.1.7, which verify overlap between the source range monitor (SRM) and intermediate range monitor (IRM), and between the IRM and average power range monitor (APRM).
An evaluation of the proposed change is provided in Attachment 1. Attachment 2 provides the existing TS pages marked up to show the proposed changes. Attachment 3 provides the existing TS Bases pages marked up to show the revised text associated with the proposed TS changes and is provided for information only.
Approval of the proposed amendment is requested by January 30, 2025. Once approved, the amendment shall be implemented within 60 days.
There are no regulatory commitments contained in this submittal. If there are any questions or if additional information is required, please contact Mr. Phil H. Lashley, Manager, Fleet Licensing, at (330) 696-7208.
Perry Nuclear Power Plant L-23-207 Page 2 of 2
I declare under penalty of perjury that the foregoing is true and correct. Executed on January vf, 2024.
7ibr~.-
Rod L Penfield /
- I
Attachments:
- 1. Evaluation of the Proposed Change
- 2. Technical Specification Page Markups
- 3. Technical Specification Bases Page Markups (for information only)
cc: NRC Region Ill Administrator NRC Resident Inspector NRR Project Manager Executive Director, Ohio Emergency Management Agency, State of Ohio (NRC Liaison)
Utility Radiological Safety Board Attachment 1 L 207
Evaluation of the Proposed Change Page 1 of 6
Subject:
License Amendment Request for Adoption of Technical Specification Task Force Traveler TSTF-264-A, Revision 0, 3.3.9 and 3.3.10 - Delete Flux Monitors Specific Overlap Requirements SRs 1.0
SUMMARY
DESCRIPTION
2.0 DETAILED DESCRIPTION 2.1 System Design and Operation 2.2 Current Technical Specifications Requirements 2.3 Reason for the Proposed Change 2.4 Description of the Proposed Change
3.0 TECHNICAL EVALUATION
4.0 REGULATORY EVALUATION
4.1 Applicable Regulatory Requirements/Criteria 4.2 Precedent 4.3 No Significant Hazards Consideration Analysis 4.4 Conclusions
5.0 ENVIRONMENTAL CONSIDERATION
L 207 Page 2 of 6
1.0
SUMMARY
DESCRIPTION
Pursuant to 10 CFR 50.90, Energy Harbor Nuclear Corp. requests an amendment to the Perry Nuclear Power Plant (PNPP) T echnical Specifications (TS). The proposed change would adopt Technical Specifications Task Force (TSTF) traveler TSTF -264-A, 3.3.9 and 3.3.10 - Delete flux monitors specific overlap requirements SRs, Revision 0, and would revise TS 3.3.1.1, Reactor Protection System ( RPS) Instrumentation, by deleting Surveillances 3.3.1.1.6 and 3.3.1.1.7, which verify the overlap between the source range monitor (SRM) and the intermediate range monitor (IRM), and between the IRM and the average power range monitor (APRM).
2.0 DETAILED DESCRIPTION
2.1 System Design and Operation
The neutron monitoring system is a system of incore neutron detectors and out -of-core electronic equipment. The system provides indication of neutron flux, which can be correlated to thermal power level for the entire range of flux conditions that may exist in the core. The SRM and the IRM provide flux level indications during reactor startup and low power operation. The local power range monitors (LPRMs) and APRM s allow assessment of local and overall flux conditions during power range operation. The neutron system provides inputs to the reactor manual control system to initiate rod blocks. The traversing incore probe (TIP) subsystem provides a means to calibrate the LPRM sensors.
2.2 Current Technical Specifications Requirements
Surveillance Requirement (SR) 3.3.1.1.6 states, Verify the source range monitor (SRM) and intermediate range monitor (IRM) channels overlap. The Frequency of SR 3.3.1.1.6 is Prior to withdrawing SRMs from the fully inserted position.
SR 3.3.1.1.7 states, Verify the IRM and APRM channels overlap. The surveillance requirement is modified by a note, which states, Only required to be met during entry into MODE 2 from MODE 1. The Frequency of SR 3.3.1.1.7 is In accordance with the Surveillance Frequency Control Program.
The reactor protection system (RPS) instrumentation for each Function i n TS Table 3.3.1.1-1, Reactor Protection System Instrumentation, shall be OPERABLE. This table is referenced to determine which SRs apply for each RPS Function. SRs 3.3.1.1.6 and 3.3.1.1.7 appear in this table.
2.3 Reason for the Proposed Change
By letter dated July 26, 1999 (ML19067A141), the NRC staff approved TSTF -264-A, Revision 0. As stated in TSTF-264-A, SR 3.3.1.1.6 and SR 3.3.1.1.7 are unnecessary in that they duplicate requirements of the CHANNEL CHECK required by SR 3.3.1.1.1.
L 207 Page 3 of 6
Failure of the SR requires that the SRM or IRM be considered inoperable even when they are calibrated and fully OPERABLE in every other way (that is, capable of performing their safety function). This is true even if it is clear that the overlap does not exist due to failure of the other flux monitors ( that is, IRMs or APRMs) since SR 3.0.1 says that failure to meet the SR is failure to meet the LCO and the SR requires overlap.
2.4 Description of the Proposed Change
The proposed change revises PNPP TS 3.3.1.1, Reactor Protection System ( RPS)
Instrumentation, by deleting SR 3.3.1.1.6 and SR 3.3.1.1.7, which verify the SRM -IRM neutron flux indication overlap and the IRM-APRM neutron flux indication overlap, respectively. SRs 3.3.1.1.6 and 3.3.1.1.7 are removed from Table 3.3.1.1-1, Reactor Protection System Instrumentation. TS 3.3.1.1 retains the surveillance number designators but replaces the surveillance statement and any associated surveillance note with the phrase Not used, and leaves the frequency column blank in the SR table rows for existing SR 3.3.1.1. 6 and SR 3.3.1.1.7. A statement is planned to be added to the TS Bases to clarify that the overlap verification is to be performed as part of the CHANNEL CHECK, SR 3.3.1.1.1.
3.0 TECHNICAL EVALUATION
TS 3.3.1.1, Reactor Protection System (RPS) Instrumentation, SRs 3.3.1.1.6 and 3.3.1.1.7, require verification of overlap for the SRM and IRM channels and verification of overlap of IRM and APRM channels.
SR 3.3.1.1.1 requires a CHANNEL CHECK of IRM and APRM channels in accordance with the surveillance frequency control program. T he CHANNEL CHECK also provides the overlap requirement since a lack of expected overlap would constitute failure of the channel to meet the established agreement criteri a. However, the agreement criteri a can be established to provide this appropriate requirement with the flexibility to determine the inoperable components and initiate appropriate actions. Therefore, the proposed change still affords adequate assurance of safety when judged against current regulatory standards.
As explained in TSTF -264-A, the definition of a CHANNEL CHECK may be interpreted as requiring SRM-IRM and IRM-APRM neutron flux indication overlap verification for the IRM and APRM associated RPS Functions that are required to be operable in Mode 2 (that is, Functions 1.a and 2.a). Therefore, consistent with TSTF -264-A, the present indication overlap verifications may be considered redundant to the channel check SR.
Differences Between the Proposed Change and the Approved Traveler:
TSTF-264-A deletes SR 3.3.1.1.6 and SR 3.3.1.1.7, renumbers all subsequent surveillances, and revises references to the renumbered surveillances. Renumbering a large number of surveillances in the plant -specific TSs would result in a prohibitive number of revisions to procedures and training materials.
L 207 Page 4 of 6
Therefore, in the Energy Harbor Nuclear Corp. proposed change, the deleted SRs are marked as Not used, and the subsequent SRs are not renumbered.
4.0 REGULATORY EVALUATION
4.1 Applicable Regulatory Requirements/Criteria
Title 10 of the Code of Federal Regulations (10 CFR), Part 50, paragraph 36(c)(3),
"Surveillance Requirements," states: Surveillance requirements are requirements relating to test, calibration, or inspection to assure that the necessary quality of systems and components is maintained, that facility operation will be within safety limits, and that the limiting conditions for operation will be met.
The proposed change does not affect compliance with these regulations or guidance and will ensure that the lowest functional capabilities or performance levels of equipment required for safe operation are met. The proposed change continues to test components to ensure that the necessary quality is maintained.
4.2 Precedent
James A. FitzPatrick Nuclear Power Plant, Docket No. 50- 333, License No. DPR -59, Amendment No. 350, Adoption of TSTF -264, Revision 0, May 27, 2022
[ML22126A196]. The safety evaluation for Amendment 350 provided approval of the approach to indicate Not used, for SRs 3.3.1.1.6 and 3.3.1.1.7 in lieu of renumbering subsequent surveillances.
4.3 No Significant Hazards Consideration Analysis
Pursuant to 10 CFR 50.90, Energy Harbor Nuclear Corp. requests an amendment to the Perry Nuclear Power Plant (PNPP) T echnical Specifications (TS). The proposed change would adopt Technical Specifications Task Force (TSTF) traveler TSTF -264-A, 3.3.9 and 3.3.10 - Delete flux monitors specific overlap requirements SRs, Revision 0, and would revise TS 3.3.1.1, Reactor Protection System ( RPS) Instrumentation, by deleting Surveillances 3.3.1.1.6 and 3.3.1.1.7, which verify the overlap between the source range monitor (SRM) and the intermediate range monitor (IRM), and between the IRM and the average power range monitor (APRM).
Energy Harbor Nuclear Corp. has evaluated whether or not 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 change involve a significant increase in the probability or consequences of an accident previously evaluated?
Response: No.
L 207 Page 5 of 6
Surveillance Requirement (SR) 3.3.1.1.6 and SR 3.3.1.1.7 are being deleted.
These SRs require verification of overlap of source range monitor (SRM) and intermediate range monitor (IRM) channels and verification of overlap of IRM and average power range monitor (APRM) channels. However, these requirements are unnecessary in that they duplicate requirements of the CHANNEL CHECK required by SR 3.3.1.1.1.
The proposed change does not affect any plant equipment, test methods, or plant operation and are not initiators of any analyzed accident sequence. The SRM, IRM, and APRM will continue to perform their function as designed.
Operation in accordance with the proposed T Ss will ensure that all analyzed accidents will continue to be mitigated as previously analyzed.
Therefore, the proposed change does not involve a significant increase in the probability or consequences of an accident previously evaluated.
- 2. Does the proposed change create the possibility of a new or different kind of accident from any accident previously evaluated?
Response: No.
The proposed change to delete SR 3.3.1.1.6 and SR 3.3.1.1.7 do es not involve a physical alteration of the plant (no new or different type of equipment will be installed), does not change the design function of any equipment, and does not change the methods of normal plant operation. The proposed change does not create any new credible failure mechanisms, malfunctions, or accident initiators not previously considered in the Perry Nuclear Power Plant design and licensing basis.
Therefore, the proposed change does not create the possibility of a new or different kind of accident from any previously evaluated.
- 3. Does the proposed change involve a significant reduction in a margin of safety?
Response: No.
The proposed change to delete SR 3.3.1.1.6 and SR 3.3.1.1.7 has no effect on any safety analysis assumptions or methods of performing safety analyses. The change does not adversely affect system OPERABILITY or design requirements.
The equipment continues to be tested via the associated CHANNEL CHECK (SR 3.3.1.1.1) in a manner and at a frequency necessary to provide confidence that the equipment can perform its intended safety functions.
L 207 Page 6 of 6
Therefore, the proposed change does not involve a significant reduction in a margin of safety.
Based on the above, Energy Harbor Nuclear Corp. concludes that the proposed amendment does not involve a 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.
4.4 Conclusions
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 Commissions 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.
5.0 ENVIRONMENTAL CONSIDERATION
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 significant increase in the amounts of any effluent s 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 impac t statement or environmental assessment need be prepared in connection with the proposed amendment.
Attachment 2 L-23-2 07
Technical Specifications Page Markups (2 pages follow)
RPS Instrumentation 3.3.1.1
SURVEILLANCE REQUIREMENTS (continued)
SURVEILLANCE FREQUENCY
SR 3.3.1.1.5 Perform CHANNEL FUNCTIONAL TEST. In accordance with the Surveillance Frequency Control Program
SR 3.3.1.1.6 Not used. Verify the source range monitor (SRM) Prior to and intermediate range monitor (IRM) channels withdrawing overlap. SRMs from the fully inserted position
SR 3.3.1.1.7 --------------------------NOTE---------------------------------
Only required to be met during entry into MODE 2 from MODE 1.
Not used. Verify the IRM and APRM channels In accordance overlap. with the Surveillance Frequency Control Program
SR 3.3.1.1.8 Calibrate the local power range monitors. In accordance with the Surveillance Frequency Control Program
SR 3.3.1.1.9 Perform CHANNEL FUNCTIONAL TEST. In accordance with the Surveillance Frequency Control Program
SR 3.3.1.1.10 Calibrate the trip unit. In accordance with the Surveillance Frequency Control Program
(continued)
PERRY - UNIT 1 3.3-4 Amendment No. 171 RPS Instrumentation 3.3.1.1
Table 3.3.1.1-1 (page 1 of 3)
Reactor Protection System Instrumentation
APPLICABLE CONDITIONS MODES OR REQUIRED REFERENCED OTHER CHANNELS FROM SPECIFIED PER TRIP REQUIRED SURVEILLANCE ALLOWABLE FUNCTION CONDITIONS SYSTEM ACTION D.1 REQUIREMENTS VALUE
- a. Neutron Flux - High 2 3 H SR 3.3.1.1.1 122/125 SR 3.3.1.1.4 divisions of SR 3.3.1.1.6 full scale SR 3.3.1.1.7 SR 3.3.1.1.13 SR 3.3.1.1.15
5(a) 3 I SR 3.3.1.1.1 122/125 SR 3.3.1.1.13 divisions of SR 3.3.1.1.15 full scale SR 3.3.1.1.19
- b. Inop 2 3 H SR 3.3.1.1.4 NA SR 3.3.1.1.15
5(a) 3 I SR 3.3.1.1.15 NA SR 3.3.1.1.19
- 2. Average Power Range Monitors
- a. Neutron Flux-High, 2 3 H SR 3.3.1.1.1 20% RTP Setdown SR 3.3.1.1.4 SR 3.3.1.1.7 SR 3.3.1.1.8 SR 3.3.1.1.11 SR 3.3.1.1.15
- b. Flow Biased 1 3 G SR 3.3.1.1.1 0.628 W +
Simulated Thermal SR 3.3.1.1.2 63.8% RTP Power - High SR 3.3.1.1.3 and 113%
SR 3.3.1.1.8 RTP(b)
SR 3.3.1.1.9 SR 3.3.1.1.11 SR 3.3.1.1.14 SR 3.3.1.1.15 SR 3.3.1.1.17 SR 3.3.1.1.18 (continued)
(a) With any control rod withdrawn from a core cell containing one or more fuel assemblies.
(b) Allowable Value is 0.628 W + 43.5% RTP when reset for single loop operation per LCO 3.4.1, Recirculation Loops Operating.
PERRY - UNIT 1 3.3-7 Amendment No. 141 Attachment 3 L-23-2 07
Technical Specifications Bases Page Markups (for information only)
(6 pages follow)
FOR INFORMATION ONLY RPS Instrumentation B 3.3.1.1
BASES
SURVEILLANCE SR 3.3.1.1.1 (continued)
REQUIREMENTS Agreement criteria are determined by the plant staff based on a combination of the channel instrument uncertainties, including indication and readability. If a channel is outside the criteria, it may be an indication that the instrument has drifted outside its limit.
The agreement criteria includes an expectation of one decade of overlap when transitioning between neutron flux instrumentation. The overlap between SRMs and IRMs must be demonstrated prior to withdrawing SRMs from the fully inserted position since indication is being transitioned from the SRMs to the IRMs. This will ensure that reactor power will not be increased into a neutron flux region without adequate indication. The overlap between IRMs and APRMs is of concern when reducing power into the IRM range (entry into MODE 2 from MODE 1). On power increases, the system design will prevent further increases (by initiating a rod block) if adequate overlap is not maintained. Overlap between IRMs and APRMs exists when sufficient IRMs and APRMs concurrently have onscale readings such that the transition between MODE 1 and MODE 2 can be made without either APRM downscale rod block, or IRM upscale rod block. Overlap between SRMs and IRMs similarly exists when, prior to withdrawing the SRMs from the fully inserted position, IRMs are above 6/125 on Range 1 before SRMs have reached the upscale rod block.
If overlap for a group of channels is not demonstrated (e.g., IRM/APRM overlap), the reason for the failure of the Surveillance should be determined and the appropriate channel(s) declared inoperable. Only those appropriate channels that are required in the current MODE or condition should be declared inoperable.
The Surveillance Frequency is controlled under the Surveillance Frequency Control Program. The CHANNEL CHECK supplements less formal, but more frequent, checks of channels during normal operational use of the displays associated with the channels required by the LCO.
To ensure that the APRMs are accurately indicating the true core average power, the APRMs are adjusted to the reactor power calculated from a heat balance if the heat balance calculated reactor power exceeds the APRM channel output by more than 2% RTP. If the heat balance calculated reactor power exceeds the APRM channel output by more than 2% RTP, the APRM is not declared inoperable, but must be adjusted consistent with the heat balance calculated power. If the APRM channel output cannot be properly adjusted, the channel is declared inoperable.
PERRY - UNIT 1 B 3.3-25 Revision No. 12 FOR INFORMATION ONLYRPS Instrumentation
B 3.3.1.1
This Surveillance does not preclude making APRM channel adjustments, if desired, when the heat balance calculated reactor power is less than the APRM channel output. To provide close agreement between the APRM indicated power and to preserve operating margin, the APRM channels are normally adjusted to within +/-2% of the heat balance calculated reactor power. However, this agreement is not required for OPERABILITY when APRM output indicates a higher reactor power than the heat balance calculated reactor power.
The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.
A restriction to satisfying this SR when < 23.8% RTP is provided that requires the SR to be met only at 23.8% RTP because it is difficult to accurately maintain APRM indication of core THERMAL POWER consistent with a heat balance when < 23.8% RTP. At low power levels, a high degree of accuracy is unnecessary because of the large inherent margin to thermal limits (MCPR and APLHGR). At 23.8% RTP, the Surveillance is required to have been satisfactorily performed in accordance with SR 3.0.2. A Note is provided which allows an increase in THERMAL POWER above 23.8% if the Frequency is not met per
(continued)
PERRY - UNIT 1 B 3.3-25 Revision No. 12 FOR INFORMATION ONLY RPS Instrumentation B 3.3.1.1
BASES
SURVEILLANCE SR 3.3.1.1.5 REQUIREMENTS (continued) A CHANNEL FUNCTIONAL TEST is performed on each required channel to ensure that the entire channel will perform the intended Function. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.
Not used. These Surveillances are established to ensure that no gaps in neutron flux indication exist from subcritical to power operation for monitoring core reactivity status.
The overlap between SRMs and IRMs is required to be demonstrated to ensure that reactor power will not be increased into a region without adequate neutron flux indication. This is required prior to withdrawing SRMs from the fully inserted position since indication is being transitioned from the SRMs to the IRMs.
The overlap between IRMs and APRMs is of concern when reducing power into the IRM range. On power increases, the system design will prevent further increases (initiate a rod block) if adequate overlap is not maintained.
Overlap (nominally 1/2 decade) between IRMs and APRMs exists when sufficient IRMs and APRMs concurrently have onscale readings such that the transition between MODE 1 and MODE 2 can be made without either APRM downscale rod block, or IRM upscale rod block. Overlap (nominally 1/2 decade) between SRMs and IRMs similarly exists when, prior to withdrawing the SRMs from the fully inserted position, IRMs are above 10/125 on range 1 before SRMs have reached the upscale rod block.
As noted, SR 3.3.1.1.7 is only required to be met during entry into MODE 2 from MODE 1. That is, after the overlap requirement has been met and indication has transitioned to the IRMs, maintaining overlap is not required (APRMs may be reading downscale once in MODE 2).
(continued)
PERRY - UNIT 1 B 3.3-27 Revision No. 11 FOR INFORMATION ONLY RPS Instrumentation B 3.3.1.1
BASES
SURVEILLANCE SR 3.3.1.1.6 and SR 3.3.1.1.7 (continued)
REQUIREMENTS If overlap for a group of channels is not demonstrated (e.g., IRM/APRM overlap), the reason for the failure of the Surveillance should be determined and the appropriate channel(s) declared inoperable. Only those appropriate channel(s) that are required in the current MODE or condition should be declared inoperable.
The Surveillance Frequency of SR 3.3.1.1.7 is controlled under the Surveillance Frequency Control Program.
LPRM gain settings are determined from the local flux profiles measured by the Traversing Incore Probe (TIP) System. This establishes the relative local flux profile for appropriate representative input to the APRM System. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.
SR 3.3.1.1.9 and SR 3.3.1.1.12
A CHANNEL FUNCTIONAL TEST is performed on each required channel to ensure that the entire channel will perform the intended function. Any setpoint adjustment shall be consistent with the assumptions of the current plant specific setpoint methodology. The Surveillance Frequency is controlled under the Surveillance Frequency Control Program.
(continued)
PERRY - UNIT 1 B 3.3-28 Revision No. 11 FOR INFORMATION ONLY SRM Instrumentation B 3.3.1.2
B 3.3 INSTRUMENTATION
B 3.3.1.2 Source Range Monitor (SRM) Instrumentation
BASES
BACKGROUND The SRMs provide the operator with information relative to the neutron level at very low flux levels in the core. As such, the SRM indication is used by the operator to monitor the approach to criticality and to determine when criticality is achieved. The SRMs are maintained fully inserted until the count rate is greater than a minimum allowed count rate (a control rod block is set at this condition). After SRM to intermediate range monitor (IRM) overlap is demonstrated (as required by SR 3.3.1.1.61), the SRMs are normally fully withdrawn from the core.
The SRM subsystem of the Neutron Monitoring System (NMS) consists of four channels. Each of the SRM channels can be bypassed, but only one at any given time, by the operation of a bypass switch. Each channel includes one detector that can be physically positioned in the core. Each detector assembly consists of a miniature fission chamber with associated cabling, signal conditioning equipment, and electronics associated with the various SRM functions. The signal conditioning equipment converts the current pulses from the fission chamber to analog DC currents that correspond to the count rate. Each channel also includes indication, alarm, and control rod blocks. However, this LCO specifies OPERABILITY requirements only for the monitoring and indication functions of the SRMs.
During refueling, shutdown, and low power operations, the primary indication of neutron flux levels is provided by the SRMs or special movable detectors connected to the normal SRM circuits. The SRMs provide monitoring of reactivity changes during fuel or control rod movement and give the control room operator early indication of unexpected subcritical multiplication that could be indicative of an approach to criticality.
APPLICABLE Prevention and mitigation of prompt reactivity excursions during refueling SAFETY and low power operation are provided by LCO 3.9.1, Refueling ANALYSES Equipment Interlocks; LCO 3.1.1, SHUTDOWN MARGIN (SDM);
LCO 3.3.1.1, Reactor Protection
(continued)
PERRY - UNIT 1 B 3.3-33 Revision No. 0 0 FOR INFORMATION ONLY SRM Instrumentation B 3.3.1.2
BASES
ACTIONS A.1 and B.1 (continued)
Providing that at least one SRM remains OPERABLE, Required Action A.1 allows 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to restore the required SRMs to OPERABLE status.
This is a reasonable time since there is adequate capability remaining to monitor the core, limited risk of an event during this time, and sufficient time to take corrective actions to restore the required SRMs to OPERABLE status or to establish alternate IRM monitoring capability.
During this time, control rod withdrawal and power increase are not precluded by this Required Action. Having the ability to monitor the core with at least one SRM, proceeding to IRM Range 3 or greater (with overlap required verified by SR 3.3.1.1. 61) and thereby exiting the Applicability of this LCO, is acceptable for ensuring adequate core monitoring and allowing continued operation.
With three required SRMs inoperable, Required Action B.1 allows no positive changes in reactivity (control rod withdrawal must be immediately suspended) due to the inability to monitor the changes. Required Action A.1 still applies and allows 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> to restore monitoring capability prior to requiring control rod insertion. This allowance is based on the limited risk of an event during this time, provided that no control rod withdrawals are allowed, and the desire to concentrate efforts on repair, rather than to immediately shut down, with no SRMs OPERABLE.
C.1
In MODE 2, if the required number of SRMs is not restored to OPERABLE status within the allowed Completion Time, the reactor shall be placed in MODE 3. With all control rods fully inserted, the core is in its least reactive state with the most margin to criticality. The allowed Completion Time of 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> is reasonable, based on operating experience, to reach MODE 3 in an orderly manner and without challenging plant systems.
D.1 and D.2
With one or more required SRM channels inoperable in MODE 3 or 4, the neutron flux monitoring capability is degraded or nonexistent. The requirement to fully insert all insertable
(continued)
PERRY - UNIT 1 B 3.3-36 Revision No. 0 0