ML25352A262
| ML25352A262 | |
| Person / Time | |
|---|---|
| Site: | 07201042 |
| Issue date: | 12/18/2025 |
| From: | Narayanan P Orano TN Americas, TN Americas LLC |
| To: | Office of Nuclear Material Safety and Safeguards, Document Control Desk |
| Shared Package | |
| ML25352A261 | List: |
| References | |
| E-65119 | |
| Download: ML25352A262 (0) | |
Text
Orano TN 7160 Riverwood Drive Suite 200 Columbia, MD 21046 USA Tel: 410-910-6900 Fax: 434-260-8480 Enclosures transmitted herein contain SUNSI. When separated from enclosures, this transmittal document is decontrolled.
December 18, 2025 E-65119 U. S. Nuclear Regulatory Commission Attn: Director of the Office of Nuclear Material Safety and Safeguards One White Flint North 11555 Rockville Pike Rockville, MD 20852
Subject:
Proposed Additional Alternative to the ACI Code, Concrete Temperature Testing, Docket 72-1042, CoC 1042 Amendment 1, Amendment 2, Amendment 3, and Amendment 4 In accordance with Paragraph 4.4.4 of Certificate of Compliance (CoC) No. 1042 Appendix A, NUHOMS EOS System Generic Technical Specifications (TS),
Amendment 1, Amendment 2, Amendment 3, and Amendment 4, TN Americas LLC (TN) requests a new proposed alternative to American Concrete Institute (ACI) 349-06, Appendix E, Section E.4-Concrete Temperatures. The current alternative cites ACI 349-13 for higher compressive strength with increased temperature. In the approval letter dated September 24, 2020 for the alternative for Amendment 1, a maximum of 56 days is imposed for the strength testing. For Amendments 2, 3, and 4, the alternative directly includes a test age of up to 56 days to allow the use of the later-age specified concrete compressive strength of 7,000 psi for horizontal storage module (HSM) fabrication.
Proposed Alternative:
The new proposed alternative to Section E.4.1 of ACI 349-06 for the HSM concrete specifications as listed in Paragraph 4.4.4 is as follows:
The concrete temperature limit criteria in NUREG-1536, Section 8.4.14.2 is used for normal and off-normal conditions.
Alternatively, per ACI 349-13, Code Requirements for Nuclear Safety-Related Concrete Structures and Commentary, Section RE.4, the specified compressive strength f'c is increased to 7,000 psi for HSM fabrication so that any losses in properties (e.g., compressive strength) resulting from long-term thermal exposure will not affect the safety margins based on the specified 5,000 psi compressive strength used in the design calculations. Additionally, also as indicated in Section RE.4, short, randomly oriented steel fibers may be used to provide increased ductility, dynamic strength, toughness, tensile strength, and improved resistance to spalling.
The safety margin on compressive strength is 40% for a concrete temperature limit of 300 °F normal and off-normal conditions.
E-65119 Document Control Desk Page 2 of 4
Background:
Section 8.4.14.2 of NUREG-1536 provides a list of rocks for concrete aggregates that are known to have a relatively low coefficient of thermal expansion. The list applies to fine and coarse aggregates.
Availability of such materials near independent spent fuel storage installation (ISFSI) sites depends predominantly on the aggregate production at local quarries, cost of transport to local concrete batch plants, and the ability of the batch plant to adapt to imported materials. No change is requested for this alternate; it is only included for completeness.
The NRC previously accepted the use of 7,000 psi concrete with no special aggregate to ensure that any losses in properties (e.g., compressive strength) resulting from long-term thermal exposure will not affect the safety margins.
The qualification of high strength concrete mixes is a lengthy and complicated process. It involves trial batching with different proportions to ensure 1) durability requirements of the ACI code are met, 2) design requirements are achieved with adequate margins, and 3) concrete performance parameters such as placeability and compactability are validated. The process often creates competing elements with air entrainment, water demand and cement content while maintaining design density and achieving the required concrete strength.
For a cast in place structure like the CoC 1042 EOS HSM (MATRIX), the 56-day requirement for compressive strength testing has created a hardship situation making performance excessively burdensome and challenging the project's economic equilibrium, for pours that are ultimately able to meet the 7,000 psi requirement with additional cure time. Therefore, TN is proposing an approach where no test age is specified in the code alternative, and concrete which meets the specified f'c per ACI 349-06 code requirements and provisions is eligible for certification.
Previous NUHOMS HSM technology designs did not include the ACI Code alternative related to this request. Although the CoC 1042 NUHOMS EOS design is based on ACI 349-06, the ACI 349-13 commentary section offered flexibility and use of increased strengths in lieu of special aggregates.
Therefore, in Amendment 0, TN proposed the alternative to ACI 349-06 Appendix E Section E.4 based on ACI 349-13 and NUREG-1536 Revision 1 Section 8.4.14.2, including the standard ACI code practice of indicating a 28-day compressive strength. TN did not intend to limit the test age to 28, 56, 91 days, or any specific number of days since the ACI allows for other designated test ages, but as written, the alternative is only limited to the 28-day and 56-day provision. Consistent with the ACI code, TN desires to use the accepted flexibility provided by that Code to be able to test for the concrete compressive strength at any designated test age, which will be specified in the design drawings or concrete specification.
TN requests this change for CoC 1042 Amendment 1, Amendment 2, Amendment 3, and Amendment
- 4.
Justification:
As demonstrated below, the proposed additional alternative will provide an acceptable level of quality and safety.
E-65119 Document Control Desk Page 3 of 4 In various sections of ACI 349-06, provisions are given for use of other than 28-day test age for determination of the specified concrete compressive strength. Excerpts from ACI 349-06 are provided below:
5.1.3 Unless otherwise specified, f'c shall be based on 28-day tests. If other than 28 days, test age for f'c shall be as indicated in design drawings or specifications.
5.6.2.4 A strength test shall be the average of the strengths of a minimum of two cylinders made from the same sample of concrete and tested at 28 days or at test age designated for determination of f'c.
R5.1.3 Concrete members 24 in. or thicker will retain sufficient moisture throughout the first 12 months to assure continuous curing and hydration of the major portion of the cross section. These large members rarely receive full service loads for many months and, therefore, the test age designated for the determination of compliance with the specified strength may be later than the usual 28 days. The use of such later age strength requirements may permit the use of a lower cement content and, therefore, help limit or control temperature rise due to hydration and the danger of cracking that may occur as these large members cool to ambient temperature levels.
The need to control early temperature rise increases in proportion to the minimum thickness of the section.
Additionally, ACI 214R recognizes alternate test ages, and states in part:
The strength of concrete at later ages, such as 56, 91, or 182 days may be more relevant than the 28-day strength, particularly where pozzolan or cement of slow strength gain is used or heat of hydration is a concern.
All other concrete specification requirements, such as sampling and testing methods, testing frequency, calculation of average strength, quality control and quality assurance requirements remain unchanged.
The proposed alternative to replace specific test age(s) with any test age to be designated in the design drawing or concrete specification and the specified concrete compressive strength of 7,000 psi (changed from the current alternative) provides the same level of quality and safety as the original requirement as the test age has no relevance to the design basis compressive strength. The HSM array will not be certified and loaded with DSCs until the specified concrete compressive strength is achieved and the safety margin on the compressive strength remains unchanged.
Regarding environmental impacts, this proposed additional alternative addresses the timing of certain concrete compressive strength testing and would, therefore, have no environmental impact with respect to the NRCs National Environmental Policy Act regulations in 10 CFR Part 51. includes a summary of HSM construction, including all testing performed, at a customer site for which this requested alternative would apply. Enclosure 1 contains TN proprietary information that may not be used for any purpose other than to support the NRC staffs review of the application.
In accordance with 10 CFR 2.390, an affidavit is provided as Enclosure 2, specifically requesting that this proprietary information be withheld from public disclosure.
E-65119 Document Control Desk Page 4 of 4 As previously discussed with NRC staff, in order to support planned HSM fabrication activities and a near term spent fuel storage loading campaign, NRC approval is respectfully requested by February 28th, 2026. If the NRC staff has any questions regarding this submittal, please do not hesitate to contact Ms. Jess Gee at 440-389-3194 or Jess.Gee@Orano.Group.
Sincerely, Prakash Narayanan Chief Technical Officer cc:
John-Chau Nguyen (NRC-DFM)
Enclosures:
- 1. Summary of HSM Construction and Testing (Proprietary)
- 2. Affidavit Pursuant to 10 CFR 2.390
to E-65119 Summary of HSM Construction and Testing Withheld Pursuant to 10 CFR 2.390 to E-65119 Page 1 of 1 TN AMERICAS LLC AFFIDAVIT PURSUANT TO 10 CFR 2.390 State of Maryland:
County of HOWARD:
I, Prakash Narayanan, depose and say that I am Chief Technical Officer of TN Americas LLC, duly authorized to execute this affidavit, and have reviewed or caused to have reviewed the information that is identified as proprietary and referenced in the paragraph immediately below. I am submitting this affidavit in conformance with the provisions of 10 CFR 2.390 of the Commissions regulations for withholding this information.
The information for which proprietary treatment is sought meets the provisions of paragraph (a) (4) of Section 2.390 of the Commission's regulations. The information is contained in Enclosure 1, as listed below:
- - Summary of HSM Construction and Testing (Proprietary)
I have personal knowledge of the criteria and procedures utilized by TN Americas LLC in designating information as a trade secret, privileged or as confidential commercial or financial information. This document has been appropriately designated as proprietary.
Pursuant to the provisions of paragraph (b) (4) of Section 2.390 of the Commissions regulations, the following is furnished for consideration by the Commission in determining whether the information sought to be withheld from public disclosure, included in the above referenced document, should be withheld.
- 1) The information sought to be withheld from public disclosure involves concrete mix testing data related to the design of the NUHOMS EOS System, which is owned by and has been held in confidence by TN Americas LLC.
- 2) The information is of a type customarily held in confidence by TN Americas LLC, and not customarily disclosed to the public. TN Americas LLC has a rational basis for determining the types of information customarily held in confidence by it.
- 3) Public disclosure of the information is likely to cause substantial harm to the competitive position of TN Americas LLC, because the information consists of descriptions of the design and validation of dry spent fuel storage systems, the application of which provide a competitive economic advantage.
The availability of such information to competitors would enable them to modify their product to better compete with TN Americas LLC, take marketing or other actions to improve their products position or impair the position of TN Americas LLCs product, and avoid developing similar data and analyses in support of their processes, methods, or apparatus.
I declare that the statements set forth in this affidavit are true and correct to the best of my knowledge, information, and belief. I declare under penalty of perjury that the foregoing is true and correct.
Executed on: December 15th, 2025 Prakash Narayanan Chief Technical Officer, TN Americas LLC