ML25343A103
| ML25343A103 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 12/12/2025 |
| From: | Kindred T Southern Nuclear Company |
| To: | Division of Operating Reactor Licensing |
| References | |
| Download: ML25343A103 (0) | |
Text
T. Kindred, P.E.
Consulting Engineer Nuclear Fuels and Analysis Plant Hatch Potential EPU Pilot Approach (2nd Tabletop)*
- SNC has not received approval to proceed with the EPU for Plant Hatch, only the engineering work, licensing, and procurement scoping of long lead items to enable EPU
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2 Purpose Overview of Plant Hatch Uprate with MELLLA+
Why is Bundling EPU/MELLLA+ Important?
Burnup Thresholds for Addressing FFRD Approach for Implementing RG-1.183 Rev. 2 (DG-1425)
Discuss Need for Pilot Exception Approach for Linked Submittals Discuss Need for Pilot Exemption Approach Overview
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3
Purpose:
To communicate SNCs strategy and invite discussion associated with key technical elements of potential upcoming EPU submittals with considerations for:
Treatment of in-process draft rule-making items (exemptions, exceptions, etc.)
Minimizing regulatory review durations through a maximization of efficiency gained from bundling/combining historically sequential submittals Continuous improvement of the safety, reliability, and overall performance of SNCs fleet of commercial power plants Purpose
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4 Continuation from 1st Pilot Workshop (ML25210A425)
Edwin I. Hatch (HNP-Units 1 and 2) plans to uprate from the current licensed thermal power (CLTP) of 2804 MWth to 121.5% of original licensed thermal power (OLTP) or 2960MWth No fuel design change/transition is planned for the HNP uprate. HNP will continue to use their current GNF3 fuel product and analyze in accordance with approved methods.
Uprate will include implementation of MELLLA+ with improved stability monitoring (DSS-CD) and will preserve the previous approval for Thermal Power Optimization (TPO) Margin Uncertainty Recapture (MUR)
Overview of Plant Hatch Uprate with MELLLA+
122 121.5 120 Power (MWth)
Basis (%)
Reference/(Year) 2436 OLTP ML012920523, ML19269E991 (1974, 1978) 2558 SPU(5)
ML013020073 (1995) 2763 EPU(8)
ML013030084, ML20155C657 (1998) 2804 TPO/MUR(1.5)
ML032691360 (2003)
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5 The MELLLA+ domain improves safety and fuel reliability by minimizing operator impact through improving operational flexibility and reducing reactivity management maneuvers upon EPU implementation Why is Bundling EPU/MELLLA+ Important?
Example showing potential reduction in reactivity maneuvers Are there any unique aspects of a combined EPU/MELLLA+ submittal that need to be included/addressed as compared to two independent submittals?
0 20 40 60 80 100 120 0
100 200 300 400 500 600 700
% Rated Power Days in Cycle Additional Reactivity Maneuvers w/o MELLLA+
EPU with MELLLA+
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6 In addition to improving safety, bundling EPU w/MELLLA+ has the potential to reduce the implementation of plant uprates by years versus a sequential submittal strategy Why is Bundling EPU/MELLLA+ Important?
A combined submittal approach with a 12-month review duration could reduce the time to accomplish an EPU by over 3 years per site (avg(53+50) - 12m) = 39m just in review savings alone!
Figure taken from ML25210A425 Combined LAR streamlines NRC resource use and supports similar future industry submissions Combined LAR makes site implementation of physical mods and procedure updates more efficient, especially in areas affected by both EPU and MELLLA+.
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7 SECY-15-0148 (ML15230A200) concluded that research and analyses provide reasonable assurance that no imminent safety concern exists with operating reactors associated with FFRD phenomena.
NUREG-2121 provides research basis for findings in SECY-15-0148 SECY-15-0148 conclusions covered operation up to and including 62 GWD/MTU rod-average burnup and 122% OLTP (BWRs) analytical power level.
Therefore, plants operating in accordance with or plants uprating within the boundaries of the 2015 fuel design limits (rod-average burnup 62 GWD/MTU and analytical power level 122% of original licensed power) are not required to address FFRD phenomena in their licensing basis.
Burnup Threshold for Addressing FFRD
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8 HNP EPU will align on a percentage power basis with plants already in operation Peach Bottom 2, 3 121.6% OLTP MELLLA+
TPO (MUR)
Peak Rod Average BU 62 GWD/MTU Burnup Threshold for Addressing FFRD Conclusions Plants utilizing existing/in-operation fuel-clad systems Plants with power levels < 122% OLTP Plants with Peak Rod Average BU 62 GWD/MTU Burnup Threshold for Addressing FFRD If plants are within/comply with the above thresholds, then the conclusions of SECY-15-0148 apply and operational/design considerations for not addressing FFRD remain applicable.
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9 As mentioned previously:
NRC provided significant effort and needed advances in dose consequence analysis guidance (ML24005A102, ML24066A177, ML24304A864) planned for RG-1.183 Rev. 2 (DG-1425).
Utilities seeking uprates for BWRs would benefit from the improved realism of the dose methods communicated in the updated guidance Credit for Suppression Pool Scrubbing Modeling guidance for pathway specific source terms (i.e. steamline leakage)
To enable uprate of HNP, SNC will utilize RG-1.183 Rev. 2 (DG-1425)
Approach for Implementing RG-1.183 Rev. 2 (DG-1425)
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10 SNC will accomplish this as follows:
Linked submittal (to EPU) for approval of an Alternative Source Term (AST) utilizing RG-1.183 Rev. 2 (DG-1425)
Licensing Precedent circa 2010:
- Turkey Point 3 and 4: EPU (ML103560169, October 2010)
- Turkey Point 3 and 4 AST: (ML092050277, June 2009)
- May require exception/revision to LIC-109
- Revision to LIC-109 would provide improved efficiency for entire industry (preferred)
Approach for Implementing RG-1.183 Rev. 2 (DG-1425)
(DG-1425 Fig. 1-2): Includes expanded application envelope which enables Rev. 2 to be used with all vendor modern fuel types as-is
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11 SNC will follow DG-1425 guidance and acceptance criteria For reasons stated above the 10 CFR 50.46 LOCA with FFRD analysis (new analysis in DG-1425) will not be performed
- Burnup and operational/fuel thresholds for addressing FFRD are not exceeded
- NRC acknowledges the MHA-LOCA source term bounds the LOCA with FFRD source term (ML21197A067)
- Consistent with recent workshop interactions (9/2025) with the staff on continued use of TID source term for EQ
- Industry acknowledges significant effort by the staff in the last year to improve regulatory durability and efficiency in this area
- Submittal package format will closely follow Vogtle RG-1.183 Rev. 1 AST (ML25190A545) with any additional considerations communicated in staff presentation ML25021A204 Will need exemption to §50.67 if I/E rule package is delayed Approach for Implementing RG-1.183 Rev. 2 (DG-1425)
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12 Approach for Implementing RG-1.183 Rev. 2 (DG-1425)
Schedule is DRAFT, formal submittal and implementation dates will be communicated by SNC Licensing O N D J F M A M J J
A S O N D J F M A M J J
A S O N D J F M A M J J
A S O N D J F M A M J J
A S O N D J F M A M J J
A S O N D SNC Develop HNP EPU w/MELLLA+ LAR NRC Review EPU LAR SNC Develop LAR RG-1.183 Rev. 2 NRC Review Rg-1.183 Rev. 2 LAR NRC Final I/E Rule NRC Draft I/E Rule O N D J F M A M J J
A S O N D J F M A M J J
A S O N D J F M A M J J
A S O N D J F M A M J J
A S O N D J F M A M J J
A S O N D Note 1: Integrated project schedule is close to completion. Updates will be provided during monthly meetings with SNC Licensing Note 2: Dates are preliminary. SNC has approval to begin engineering, licensing, and early procurement work Note 3: Draft and Final I/E Rule includes updates to RG-1.183 Rev. 2 2025 2026 2027 2028 2029 2030 2025 2026 2027 2028 2029 2030
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13 LIC-109 SNC believes including AST Rev. 2 with the EPU LAR would result in a significant increase in complexity for the EPU LAR Review approach currently in progress for Vogtle 1 and 2 EPU should be used.
Due to schedule constraints and longer lead key task predecessors (i.e. loading patterns for ORIGEN depletion calculations) linked submittals should be allowed for this:
- It is expected significant changes to DG-1425 will be communicated in 2Q26 when the rule becomes available for comment
- To reduce risk and cost of re-work, utilities should not begin LAR analysis work until the public comment period
- Prior to LIC-109 this was allowed (maybe it still is?)
Discuss Need for Pilot Exception Approach for Linked Submittals Discussions on how this approach can be achieved 3.1 Acceptance Review Criteria The following sections highlight key elements that should be contained in an RLA and potential issues that should be addressed during the acceptance review. The PMs and technical staff should make the following determinations with regard to the RLA. Failure of an RLA to meet one or more of the following criteria is indicative of an unacceptable application. However, the criteria are not all-inclusive or absolute, and NRC staffs discretion and judgement should be used in the process. Application of the criteria should not replace sound technical and regulatory judgement. The list of criteria are divided into groups by which reviewer (PM or technical staff) would likely be utilizing them.
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14 Exemption for §50.67 (b)(2)(iii)
To be consistent with proposed criteria in Tables 7 and 8 of DG-1425 an exemption to §50.67 (b)(2)(iii) will be needed (if the rule is not implemented by the time of planned submittals) as the criteria in the current rule is different from the criteria in the draft guidance Industry could submit an exemption request for approval of the Risk-Informed Performance Based Control Room Design Criteria, but the foundational technical basis and justification for this criteria is based on work performed by the staff:
- White Paper on a Graded, Risk-Informed and Performance-based framework (ML24212A254)
- Assessment of Health Effects (ML23027A059)
- Positive feedback when presented to ACRS (12/2024)
Discuss Need for Pilot Exemption Approach
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15 What if any contingencies can be implemented to offset any future obstacles such as those encountered in October/November Plans for HNP are strongly tied to the progression of the I/E rule Are there additional things we can do? (LIC-112)
Additional Items and Contingencies
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