ML22010A066

Supplemental Information to License Amendment Request, Decommissioning Technical Specifications

ML22010A066
Person / Time
Site:	Three Mile Island
Issue date:	01/05/2022
From:	Gerard van Noordennen TMI-2 Solutions
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
TMl2-RA-COR-2022-0001
Download: ML22010A066 (5)

Text

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TMl-2 SOLUTIONS

January 5, 2022

TMl2-RA-COR-2022-0001 10 CFR 50.90

U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001

Subject:

Supplemental Information to License Amendment Request-Three Mile Island, Unit 2, Decommissioning Technical Specifications Three Mile Island, Unit 2 NRG Possession Only License No. DPR-73 NRG Docket No. 50-320

References:

(1) Letter TMl2-RA-COR-2021-0002 from van Noordennen (TMl-2 Solutions LLG) "License Amendment Request-Three Mile Island, Unit 2, Decommissioning Technical Specifications," (ML21057A047) dated February 19, 2021.

(2) Letter TMl2-RA-COR-2021-0010 from van Noordennen (TMl-2 Solutions LLC) "Supplemental Information to License Amendment Request - Three Mile Island, Unit 2, Decommissioning Technical Specifications,"

(ML21057A047) dated May 5, 2021.

On February 19, 2021, TMl-2 Solutions submitted an application for a license amendment for Three Mile Island Nuclear Station; Unit 2 ("TMl-2") to revise the Possession Only License and the associated Technical Specifications to support the transition of TMl-2 from a Post-Defueling Monitored Storage (PDMS) condition to that of a facility undergoing radiological decommissioning (DEGON) (Reference ~ ). Ori May 5, 2021, TMl-2 Solutions submitted a s.upplement to the application submitted on February 19, 2021 (Reference 2). Specifically, this letter transmitted additional information related to a calculation that was submitted in Reference 1 that provides the basis for establishing a new Safe Fuel_ Mass Limit (SFML). This letter transmits some clarifying information based on input received on Reference 2. Attachment 1 contains a response to questions on the analysis. Attachment 2 contains a revision to TMl2-EN-RPT-0001 "Determination of the Safe Fuel Mass Limit for Decommissioning TMl-2" based on the responses to the questions in Attachment 1. Attachment 3 contains a revision to TMl2-EN-RPT-0002 "MCNP Version 6.2 Bias Determination for Low Enrichment Uranium Using the ENDF/B-VIII.0 Cross Section Library" based on the responses to the questions in Attachment 1.

In accordance with 10 CFR 50.91(b)(1), a copy of this submittal has been sent to the Commonwealth of Pennsylvania. /t /) b /

TMl2-RA-COR-2022-0001 Page 2 of 3

In the event that the NRC has any questions with respect to the content of this document or wishes to obtain any additional information, please contact me at 860-462-9707.

I declare under penalty of perjury that the foregoing is true and cor rect. Executed on January 5, 2022.

Sincerely,

Digitally signed by Gerard van Noordennen Gerard van DN : cn=Gerard van Noordennen, o=EnergySolulion s, ou = Regulatory Affairs, Noordennen email=gpvannoordennen @energysolutions.com, c=US Date: 2022.01.05 13:14:25 -05'00 '

Gerard van Noordennen Senior Vice President Regulatory Affairs

Attachments: - Response to Questions on SFML Analysis - Revision to TMl2-EN-RPT-0001 "Determination of the Safe Fuel Mass Limit for Decommissioning TMl-2" - Revision to TMl1-EN-RPT-0002 "MCNP Version 6.2 Bias Determination for Low Enrichment Uranium Using the ENDF/B VI 11.0 Cross Section Library "

cc w/Attachments Ted Smith, NRC Project Manager NRC Region I Administrator NRC Lead Inspector TMl2-RA-COR-2022-0001 Page 3 of 3

TMl-2 Service List cc w/ Attachments:

Ken Robuck Director, Bureau of Radiation Protection President and CEO Department of Environmental Protectio~

Energy Solution s Commonwealth of Pennsylva n ia '

299 South Main Street, Suite 1700 Ra c hael Carson State Office BLDG.

Salt Lake City, UT 84111 13TH Floor P.O. Box 8469 John Sauger Harrisburg, PA 17105-8469 President and Chief Nuclear Officer Chief, Division of Nuclear Safety, Bureau of Reactor D&D Radiation Protection,

Energy Solutions Department of Environmental Protection 121 W. Trade Street, Suite 2700 Commonwealth of Pennsylvania '

Charlotte, NC 28202 Rachael Carson State Office BLDG.

Mike Lackey 13TH Floor Senior Vice President P.O. BOX 8469 D&D Operations Harrisburg, PA 17105-8469 Energy Solutions Chairman, Board of County Commissioners,

121 W. Trade Street, Suite 2700 Dauphin County Charlotte, NC 28202 112 Market Street Gerard van Noordennen 71h Floor Senior Vice President Regulatory Affairs Harrisburg, PA 17101 Energy Solutions Chairman, Board of Supervisors of 121 W. Trade Street, Suite 2700 Londonderry Township Charlotte, NC 28202 783 S. Geyers Church Rd.

Frank Helin Middletown PA 17057 Project Director Trevor Orth TMl-2 Solutions Site Decommissioning Director 121 W. Trade Street, Suite 2700 Three Mile Island Generating Station Charlotte, NC 28202 Route 441 South

Russ Workman Middletown, PA 17057 General Counsel Energy Solutions Craig W Smith 299 South Main Street, Suite 1700 Site Decommissioning Regulatory Salt Lake City, UT 84111 Assurance Lead Daniel F. Stenger Three Mile Island Generating Station Hogan Lovells US LLP Route 441 South 555 13th St NW Middletown, PA 17057 Washinqton, D.C. 20004 Attachment 1 to TMl2-RA-COR-2022-0001

Supplemental Information to License Amendment Request

Three Mile Island Nuclear Station, Unit 2

NRC Possession Only License No. DPR-73

Response to Questions on SFML Analysis Co m m e nt Re spon se Section 1.2 and 6.3 of the va lidation report ha ve been updated with the MoS terminology and it's derivation. It is al so included The Safe Mass Cale correctly uses the term " margin of subcriticality a s part of Section 7. Section 2.2. 2 of the SFML calcu lation (MoS) " however, the validation report incorrectly uses the term " margin report ha s been updated to be consistent with the validation of safety (MoS) " in this same context. This is not semantics ; it is report.

important to distinguish between these two terms as they are not at all the same. Margin of safety refers to margin in terms of NCS parameters 1 (e.g., setting the mass limit at 8kg when the calcs demonstrate that the actual safe mass is 12kg, or setting the maximum column diameter to 4" when the calcs demonstrate it's safe up to 5" ). Margin of subcriticality refers to margin in terms of direct margin in k_ eff (e.g., setting USL at 0.95 instead of 0.98 or 1.00). The margin of safety can (and does) have an impact on subcritical margin ; however, the impact is indirect and non -

linear (e.g., a 2% margin in safety does not necessarily correspond to a 2% sub c ritic al margin). A 5% change in moderation could yield a 20 %

change in k elf, etc.

See abo ve section c hange s.

The validation report states that the "... MoS should be determined on a case -by - case basis... " however, this is inconsistent with the way the NRC treats sub c ritic al margin. I understand that this project does not fall under 10 CFR 70, but typically the NRC reviews and approves an 2 applicant ' s minimum margin of subcriticality based on the rigor of validation ; similarity, quality, and quantity of the benchmark experiments used in validation ; statistical methodology of validation ;

conservatism in treatment of NCS parameters and modelling assumptions ; etc. This needs to be discussed with the licensee and we need to get together to decide how to handle this as this is something that needs to be under the NRC's control and not potentially changed under the licensee' s own authority now or at some point in the future.

The Safe Mass Cale/validation report states that the MoS is justified A more detailed justification has been added to Section 6.3 in based on conservative assumptions. While this can be part of the the v alidation report.

3 justification, this is not nearly enough. An argument needs to be provided that references the rigor of the validation and all other things noted above in No. 2 The validation report states that " the bias minus the MoS is the USL. " The bia s uncertainty was originally quantified in the validation There is no discussion and / or quantification of the bias uncertainty or report (Section 5.4). Text has been added to clarify how and 4 calculational uncertainty. The USL should be as follows: USL > k_calc where it is addressed. See Section 1.2 and Table 1 for changes.

+2sigma_calc >bias+ sigma_bias + MoS + any penalty for extensions to the AOA.

There is no discussion as to how the penalty for an AOA extension would Section 6.2 of the validation report has added text regarding 5 be determined. We need at least a methodology. AOA extension.

6 The bias is not defined correctly. Text is added to Section 1.2 of the va lidation report for the Moc, and 1-MoC as the bias.

7 In the AOA, both the fissile materials and fissile geometries need to The AOA table has been updated in both the validation report specified; they are too general. (Table 2) and the calculation report (Table 2-1).

Do any current or planned calcs fall outside of the AOA? There are no plans for any future calculations and no current 8 ca lculations fall outside of the AOA. This has been stated in the va lidation report Section 6.2.

Does credit for impurities, including absorbers, assume that they are The impurities are uniformly and homogeneously distributed 9 of uniform spatial distribution? through each fuel kernel within the lattice. A statement was added in Section S.1, and a bullet was added in Section 5.2 of the SFML calcu lation report.

What is the basis for assuming spheres of fuel surrounded by moderato r Some explanation for the core geometry model is in the third 10 in a lattice vs. a true homogeneous mixture? report, which is not being revised. That is the Input Consensus report. Some text has been added to Section 5.2 of the SFML calculation report.

Will the activities be monitored by some kind of criticality accident Ba sed on high ba ckground radiation levels, physical underwater alarm system? separation of waste processing location s in the canal, a SFML calculation bounding of all remaining material on site, that the remaining material on site is distributed across mu ltiple large plant component s, and defense in depth via an operating sequence based on individually handling and disposing of large 11 components, the Project considers a criticality event to be of exceedingly low likelihood and would not be fea sible for the activities planned. Therefore, the Project is not planning on a traditional CAAS. However, the project is evaluating additional operational controls and alternate methods of detection.