ML25092A179
| ML25092A179 | |
| Person / Time | |
|---|---|
| Site: | 07109389 |
| Issue date: | 04/17/2025 |
| From: | Storage and Transportation Licensing Branch |
| To: | |
| Shared Package | |
| ML25092A176 | List: |
| References | |
| EPID L-2024-LLA-0036 | |
| Download: ML25092A179 (1) | |
Text
Enclosure 2 SAFETY EVALUATION REPORT DOCKET NO. 71-9389 MODEL NO. TN-40HT PACKAGE CERTIFICATE OF COMPLIANCE NO. 9389, REVISION NO. 1 1.0
SUMMARY
By letter dated April 25, 2024 (Agencywide Documents Access and Management System Accession No. ML24116A212), as supplemented by letter dated March 10, 2025 (ML25069A604), and April 7, 2025 (ML25098A122), TN Americas LLC (TN or the applicant) submitted an application, as required by Title 10 of the Code of Federal Regulations (10 CFR)
Part 71, to the U.S. Nuclear Regulatory Commission (NRC) for revision to Certificate of Compliance (CoC) No. 9389 for the Model No. TN-40HT transport package. The proposed revision would add a new American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code alternative for TN-40HT fabrication. Previously, the NRC issued CoC No. 9389, Revision No. 0, for the Model No. TN-40HT package on December 27, 2023 (ML23360A006).
Specifically, the application requested a change to the CoC to allow the use of ASME B&PV Code, section III, alternative to the surface examination requirements of NB-5130 for the TN-40HT casks, which would be captured in the TN-40HT ASME Code Alternatives table in appendix 1.6.3 of the TN-40HT safety analysis report (SAR). The requirements in NB-5130 state that all full penetration weld edge preparation surfaces for joints in material that are 2 inches (50 millimeters) or more in thickness be examined by the magnetic particle or liquid penetrant method. In addition, NB-5130 includes acceptance standards for the evaluation of indications. The proposed alternate tests, in lieu of the surface examinations requirements of NB-5130, consist of a restricted radiographic testing examination (RT) with more restrictive acceptance criteria than the requirements of NB-5320, or a supplementary phased array ultrasonic testing (PAUT) examination. The SAR appendix 1.6.3, ASME Code Alternatives, table revisions incorporate the ASME B&PV Code, section III, alternative to the surface examination requirements.
The staff used the guidance in NUREG-2216, Standard Review Plan for Transportation Packages for Spent Fuel and Radioactive Material, to perform the review of the proposed packaging changes. Based on the statements and representations in the application and the conditions listed in the following evaluation, the staff concludes that the package meets the requirements of 10 CFR Part 71.
2.0 SAFETY EVALUATION Description of Changes The applicant stated that the proposed change is to allow the use of an ASME B&PV Code,Section III, alternative to the surface examination requirements of NB-5130 for the TN-40HT casks, which would be captured in the TN-40HT ASME Code Alternatives table in appendix 1.6.3 of the TN-40HT SAR. The proposed alternate tests consist of a RT with more restrictive acceptance criteria or a supplementary PAUT examination.
2 The applicant stated that the shell flange side of the shell flange to inner shell weld, if 2 inches (50 millimeters) or more in thickness at the time of welding, may be exempt from the magnetic particle or liquid penetrant examination required by NB-5130, provided Conditions 1 and 2 below are met:
1.
The shell flange is produced from a forging.
2.
The volumetric examination of the completed weld shall be modified or supplemented under option a or b below:
a.
RT: The acceptance standard for RT of the completed weld joint shall be tightened (smaller allowance of defects). The criterion for elongated indications shall be NB-5320(b)(1) instead of NB-5320(b)(2). This tighter criterion shall be applied in addition to NB-5320(a), (c), (d), and (e), without change. In addition, tighter criteria for the selection of penetrometers per NB-5111(a) shall be applied. A 0.016-inch diameter source side image quality indicator wire shall be used as the essential wire. The area of interest shall cover the weld, the weld volume and 0.5 inches beyond the toe of the weld on the forging side.
b.
PAUT: PAUT shall be performed on the completed weld joint with a defined area of examination of the weld surface and 0.5 inches beyond the toe of the weld on the forging side. The PAUT is in addition to completion of RT of the joint with acceptance standards of NB-5320 without modification. The acceptance standards of the PAUT shall be NB-5331(a)(1) and (b). Later editions of the ASME section V can be used for completion of the PAUT procedure and qualification.
The applicant noted that the use of this alternative is optional. The surface examination required by paragraph NB-5130 may still be used.
Staff Evaluation of Changes As noted in NUREG-2216, section 7.4.4, applicants should identify the codes and standards for the design and construction of packages and verify that the application justifies the Code alternatives in order to enable an assessment of their acceptability. Paragraph NB-5130 of the ASME code requires that all full penetration weld edge preparation surfaces for joint categories A, B, C, D, and similar joints in material two inches (50 millimeters) or more in thickness shall be examined by the magnetic particle or liquid penetrant method. The purpose of the non-destructive examination (NDE) is to detect discontinuities on, near, or open to the surface of the material to be welded, that could propagate during welding and result in rejection of the weld in later weld examination.
The tests and examinations that are currently required by the ASME Code and the TN-40HT CoC to provide assurance of the final quality of the weld are as follows:
MT or PT of the surface of the weld to the acceptance criteria of NB-5340 or NB-5350, Hydrostatic testing to 1.25 times the design pressure followed by MT or PT examination in accordance with NB-6200 and NB-5410, and Helium leak-testing per the American National Standards Institute N14.5 to the acceptance criteria of 10-7 reference cubic centimeters per second.
3 The applicant stated that laminar defects are the greatest concern as the types of discontinuities that could propagate during welding and would result in extensive repairs to the weld joint. The applicant also stated that non-laminar indications could exist in a machined surface of a weld preparation. To address this, the applicant proposed the alternatives in addition to the tests and examinations that are currently required by the ASME Code and TN-40HT CoC.
The alternative described below provides further assurance of the acceptability of the final weld, along with the following proposed changes to the NDE required of the final weld. The fabricator could select either of the two options in the second condition described below, which are found equivalent in terms of the final results of the weld:
As an alternative to the NDE required by paragraph NB-5130, the applicant proposed the following conditions:
1.
The shell flange shall be made from forging material only. Plate material is not allowed.
2.
Volumetric NDE of the final weld and 0.5 inches of base metal on the side of the forging shall include one of the following two options:
a.
Option 1, RT acceptance standard uses NB-5320(b)(1) instead of NB-5320(b)(2).
NB-5320(a), (c), (d), and (e) apply without modification in addition to tightened penetrometer requirements of NB-5111(a). Reduce Max indication size from NB-5320(b)(2) requirement of 0.5 inches to 0.25 inches. Source Side Image Quality Indicator wire size for the 1.50 inches thick material reduced from NB-5111(a) requirement of 0.032 inches to 0.016 inches.
b.
Option 2, PAUT is performed on the completed weld joint with a defined area of examination of the weld surface with acceptance standard of NB-5331(a)(1) and (b) and 0.5 inches beyond the toe of the weld on the forging side after completion of RT with acceptance standard of NB-5320 without modification.
The NRC staff had previously approved the applicants proposed ASME Code Alternative for the Prairie Island (PI) Independent Spent Fuel Storage Installation (ISFSI) TN-40HT cask (ML24008A131). The bases for acceptance in the PI ISFSI were that the proposed alternative NDE was consistent with the guidance of NUREG-2215, section 8.5.3, for welding processes that are not fully consistent with the ASME code; as a result the staff determined that either the enhanced RT or the PAUT, along with the existing tests and examinations contained in the license is sufficient to ensure the quality and structural integrity of the shell flange to inner shell welds for the TN-40HT design. In this application, the applicant has requested the alternatives be made available in the CoC for the TN-40HT transportation cask.
The NRC staff has reviewed the proposed alternatives in this application to the required NDE of paragraph NB-5130 and verified that the applicant has provided a sufficient description and technical basis for the proposed alternative NDE, consistent with the guidance of NUREG-2216, section 7.4.3, Weld Design and Inspection, for welding processes that are not fully consistent with ASME code.
The NRC staff determined either the enhanced RT or the PAUT, along with the existing tests and examinations contained in the CoC, is sufficient to ensure the quality and structural integrity of the shell flange to inner shell welds, for the TN-40HT design. The staff finds that the applicant has demonstrated the proposed alternative provides an acceptable level of quality and safety.
4 The staff determined that the applicant has met the requirements in 10 CFR 71.31(c) because the applicant identified the applicable codes and standards for the design, fabrication, testing, and maintenance of the package and, in the absence of codes and standards, has adequately described controls for material qualification and fabrication.
3.0 CONDITIONS The following conditions are added into CoC No. 9389:
Condition 10 states that CoC No. 9389, Revision 0, for the Model No. TN-40HT remains valid for a year from the date of issuance for CoC No. 9389, Revision 1.
Condition 11, previously listed as Condition 10 in CoC No. 9389, Revision 0, provides the expiration date of CoC No. 9389. The expiration remains the same as it was for CoC No. 9389, Revision 0.
4.0 CONCLUSION
Based on the review of the statements and representations in the application, the NRC staff concludes that the materials used in the transportation package are adequately described and evaluated, and that the Model No. TN-40HT package meets the requirements of 10 CFR Part 71.
Issued with CoC No. 9389, Revision No. 1, dated April 17, 2025