JAFP-24-0055, Response to Request for Additional Information for License Amendment Request to Add Temporary Change to TS 3.3.2.1, Condition C, Control Rod Block Instrumentation
| ML24303A408 | |
| Person / Time | |
|---|---|
| Site: | FitzPatrick  |
| Issue date: | 10/29/2024 |
| From: | Para W Constellation Energy Generation |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| JAFP-24-0055, EPID L-2024-LLA-0134 | |
| Download: ML24303A408 (1) | |
Text
10 CFR 50.90 JAFP-24-0055 October 29, 2024 United States Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 James A. FitzPatrick Nuclear Power Plant Renewed Facility Operating License No. DPR-59 NRC Docket No. 50-333
Subject:
Response to Request for Additional Information for License Amendment Request to Add Temporary Change to TS 3.3.2.1, Condition C, Control Rod Block Instrumentation
References:
- 1.
Letter from W. Para (Constellation Energy Generation, LLC) to U.S.
Nuclear Regulatory Commission, "License Amendment Request -
Temporary Addition to TS 3.3.2.1 Condition C, Control Rod Block Instrumentation to Support Upgrade to Rod Worth Minimizer Software,"
JAFP-24-0047, ML24269A132, dated September 25, 2024 2.
Letter from R. Lantigua, Project Manager, U.S. Nuclear Regulatory Commission, " RAIs for JAFP-24-0047 (EPID L-2024-LLA-0134),"
ML24298A138, dated October 24, 2024 By letter dated September 25, 2024 (Reference 1), Constellation Energy Generation, LLC (CEG) requested to temporarily change the James A. FitzPatrick Nuclear Power Plant (JAF)
Technical Specifications (TS) for the operability of the Rod Worth Minimizer (RWM) during reactor startup. The change adds a footnote to TS 3.3.2.1, Condition C, permitting reactor startup with the RWM inoperable and while a compensatory measure is in place.
On October 15, 2024, the NRC Project Manager for JAF emailed draft Request for Additional Information (RAI) questions necessary to complete their review. On October 24, 2024, a clarification call was conducted with the NRC to ensure understanding of the draft RAI questions. Also, on October 24, 2024, and following the clarification call, the NRC Project Manager issued the final RAI questions (Reference 2). to this letter contains the NRCs RAI questions immediately followed by CEGs responses.
CEG has reviewed the information supporting the No Significant Hazards Consideration and the Environmental Consideration that was previously provided to the NRC in Reference 1.
The additional information provided in this submittal does not affect the conclusion that the proposed license amendment does not involve a significant hazards consideration. This 200 Energy Way Kennett Square, PA 19348 www.constellation.com
Response to Request for Additional Information JAF Rod Worth Minimizer Temporary TS Change Docket No. 50-333 October 29, 2024 Page 2 additional information also does not affect the conclusion that neither an environmental impact statement nor an environmental assessment need be prepared in support of the proposed amendment.
This letter contains no new regulatory commitments.
Should you have any questions concerning this submittal, please contact Ron Reynolds at 267-533-5698.
I declare under penalty of perjury that the foregoing is true and correct. Executed on the 29th day of October 2024.
Respectfully, Wendi Para Senior Manager - Licensing Constellation Energy Generation, LLC
Attachment:
Response to Request for Additional Information cc:
USNRC Region I, Regional Administrator w/attachment USNRC Senior Resident Inspector, JAF USNRC Project Manager, JAF A. L. Peterson, NYSERDA B. Frymire, NYSPSC A. Kauk, NYSPSC
ATTACHMENT 1 James A. FitzPatrick Nuclear Power Plant Renewed Facility Operating License No. DPR-59 NRC Docket No. 50-333 Response to Request for Additional Information
Response to Request for Additional Information Page 1 of 4 JAF Rod Worth Minimizer Temporary TS Change Docket No. 50-333 By application dated September 25, 2024 (Agencywide Documents Access and Management System Accession No. ML24269A132), Constellation Energy Generation, LLC (CEG) submitted a license amendment request (LAR) to change the Technical Specifications (TS) for the James A. FitzPatrick Nuclear Power Plant (JAF) Renewed Facility Operating License DPR-59. CEG requested to change TS 3.3.2.1 Condition C for the operability of the rod worth minimizer (RWM) during reactor startup. The change would add a footnote to TS 3.3.2.1 required action C.2.1.2 to permit reactor startup with the RWM inoperable while an additional compensatory measure is implemented. The footnote would expire on December 31, 2024.
The U.S. Nuclear Regulatory Commission (NRC) staff has reviewed the information provided by the licensee in its application and has determined that the staff needs the following additional information to complete its review of the LAR. As discussed with licensee staff on October 24, 2024, NRC is requesting the licensee to respond to the request for additional information (RAI) on or by October 29, 2024.
Regulatory Basis Title 10 of the Code of Federal Regulations (10 CFR), Part 50, Appendix A, general design criterion (GDC) 10, "Reactor design," states that the reactor core and associated coolant, control, and protection systems shall be designed with appropriate margin to assure that specified acceptable fuel design limits are not exceeded during any condition of normal operation, including the effects of anticipated operational occurrences.
10 CFR 50, Appendix A, GDC 28, "Reactivity limits," states that the reactivity control systems shall be designed with appropriate limits on the potential amount and rate of reactivity increase to assure that the effects of postulated reactivity accidents can neither (1) result in damage to the reactor coolant pressure boundary greater than limited local yielding nor (2) sufficiently disturb the core, its support structures or other reactor pressure vessel internals to impair significantly the capability to cool the core. These postulated reactivity accidents shall include consideration of rod ejection (unless prevented by positive means), rod dropout, steam line rupture, changes in reactor coolant temperature and pressure, and cold water addition.
RAI 1
The application states:
Control rod withdrawal errors are considered when the reactor is at power levels below the power range. The most severe case occurs when the reactor is just critical at room temperature and an out-of-sequence rod is continuously withdrawn. Procedural controls supplemented by the RWM would normally prevent withdrawal of such a rod. It is assumed that the Intermediate Range Neutron Monitoring (IRM) channels are in the worst conditions of allowed bypass.
The scaling arrangement of the IRMs is such that for unbypassed IRM channels a SCRAM signal is generated before the detected neutron flux has increased by more than a factor of ten. In addition, a high neutron flux SCRAM is generated by the average power range monitors.
Response to Request for Additional Information Page 2 of 4 JAF Rod Worth Minimizer Temporary TS Change Docket No. 50-333 This statement is also found in the description of analyzed abnormal operational transients in the Updated Final Safety Analysis Report (UFSAR), Section 14.5.4.2, "Continuous Rod Withdrawal During Startup." UFSAR Section 14.4.1, "Approach to Safety Analyses - General,"
also assumes that this abnormal operational transient does not result in fuel damage.
Provide a justification as to whether an inoperable RWM during this abnormal operational transient can result in any calculated damage to the fuel.
The control rod withdrawal pattern is in accordance with banked position withdrawal sequence (BPWS) and it is enforced by the RWM; or, if the RWM is bypassed, by procedural controls with a control room operator. An out of sequence control rod is assumed to be continuously withdrawn by the Rod Withdrawal Error (RWE) transient evaluation.
The RWE transient at low power is assumed to be arrested by the IRM. If the IRM high power rod block fails to arrest the associated power excursion, the transient is terminated by the IRM scram. As described by Technical Specification (TS) Bases 3.3.2.1, below 30% power, the consequences of an RWE event will not exceed the safety limit minimum critical power ratio (SLMCPR). Therefore, an inoperable RWM will not result in violation of the SLMCPR or damage to the fuel.
The use of a second operator required for reactor startups without the RWM has previously been found to be acceptable in JAF TS Amendment 155. Additional procedural controls are established to verify control rod pattern upon completion of each RWM group, in the absence of an operable RWM.
RAI-2
The application states:
In considering the possibilities of a control rod drop accident, only the rod worths of the lower curve of UFSAR Figure 14.6-1 are pertinent at less than 10 percent power. These are the rods which are normally allowed to be moved by operating procedures and the RWM. The nonscheduled rods, those within the central envelope, do not have a withdrawal permissive during the time their worths are greater than the lower curve, so they are held full in by the control rod drive and cannot drop from the core. If a nonscheduled rod were selected, the RWM blocks rod movement.
The application also states:
The control rod drop accident is defined as the assumed drop of the highest worth rod that can be developed at any time in core life or plant operating conditions by one error on the part of the operator. The RWM, which would normally prevent the operator from moving this rod, is assumed not to function.
Response to Request for Additional Information Page 3 of 4 JAF Rod Worth Minimizer Temporary TS Change Docket No. 50-333 The NRC staff is requesting the following information to understand the existing failure modes of the RWM and how they relate to the analysis for the control rod drop accident.
- a. Provide a justification for crediting the RWM blocking nonscheduled rod movement given the continuing unreliability of the RWM system or describe other means used to minimize the consequences of a control rod drop accident.
- b. Clarify whether the RWM is assumed to function in the control rod drop accident scenario evaluated at less than 10 percent power.
- a. The current RWM reliability issues are associated with blocking control rod motion when the movement is allowed by BPWS, or by a failure of the system to re-initialize. They have not been associated with failure to block control rod movement, when required. A system failure to reinitialize creates a rod block when below the TS required power level and is annunciated via the process computer. Normal control rod movement is not possible under these conditions without positive operator action to place the system in bypass by keylock.
Upon review of the previous six credited occurrences of ST-20A, Rod Worth Minimizer Functional Test, corresponding to the previous six startups, there were five successful performances and one unsuccessful performance due to the RWM being unable to be re-initialized.
Consequently, there are no concerns with the ability of the RWM to enforce compliance with BPWS while in service and relied upon as an operable system.
- b. The control rod pattern prior to the limiting control rod drop accident is assumed to be in compliance with the BPWS. This results in limiting control rod worths which are equal to or less than 1.2% delta K. As a conservative assumption, design basis control rod worth for the dropped control rod is assumed at 2.5% delta K. JAF initial core results described in the Final Safety Analysis Report (FSAR) suggest that the consequences of a latent error of an out of sequence control rod experiencing a control rod drop would continue to meet design requirements of 280 calories per gram. The substantial margin of safety for control rod drop accidents (CRDA), provided adherence to the banked position withdrawal sequence, was used by JAF to exempt the control rod drop accident from reload analysis.
Due to this assumption, the CRDA is consequently reliant on the enforcement of the BPWS by either the RWM or by multiple operators enforcing adherence to the BPWS.
A probabilistic evaluation performed across boiling water reactors and accepted by the NRC determined that the low frequency of occurrence and substantial margin of safety results in unacceptable dose consequences of the control rod drop accident at a frequency of 10-12 per reactor year, assuming the control rod dropped is not in compliance with the banked position withdrawal sequence. This low likelihood was provided as justification for relaxation of the Rod Sequence Control System and reliance on a single train system (the RWM) or control room staff alone in TS Amendment 155.
Response to Request for Additional Information Page 4 of 4 JAF Rod Worth Minimizer Temporary TS Change Docket No. 50-333
RAI-3
The submittal discusses a proposed compensatory measure for reactor startups without an operable RWM:
JAF will take the following compensatory measure: JAF will dedicate an independent third-party review of the rod movement sheets.
Beyond the compensatory measure described above, the site will also take the existing TS 3.3.2.1 Action C.2.2 to have a second licensed operator or other qualified member of the technical staff verify movement of control rods is in compliance with BPWS.
In addition to the above TS required action, per procedure, control rod movement for startup will take place in accordance with BWR Control Rod Movement Requirements, OP-AB-300-1001, which requires a second licensed operator to perform all Main Control Room peer checks per CEGs management model. Also, in accordance with CEGs management model, control rod movement during a startup is overseen by a dedicated Reactivity Management Senior Reactor Operator who acts to ensure all planned control rod movement is performed in accordance with approved procedures.
The licensee proposes to capture these actions in a TS Note, which would state, "*Reactor startup with the RWM inoperable is permitted while the compensatory measure described in letter JAFP-24-0047 dated September 25, 2024, is implemented. This allowance expires on 12/31/2024 at 23:59. "
- a. Clarify when this independent third-party review of the rod movement sheets will take place (e.g., prior to startup, concurrent with, etc.)
- b. Explain why the licensee did not propose the compensatory measures to be listed directly in the TS Note.
- a. The third-party review of the rod movement sheets is required to take place prior to movement of the associated control rod for startup.
- b. Consistent with precedent, one-time limited duration annotations refer to the license amendment request, including the applicable time limit. The human factors for use of this footnote are adequate as requested by the LAR.