ML26076A168
| ML26076A168 | |
| Person / Time | |
|---|---|
| Site: | 07109372 |
| Issue date: | 03/24/2026 |
| From: | Storage and Transportation Licensing Branch |
| To: | |
| References | |
| Download: ML26076A168 (3) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 SAFETY EVALUATION REPORT Docket No. 71-9372 Model No. TN-B1 Package Certificate of Compliance No. 9372 Revision No. 6
SUMMARY
By letter dated December 4, 2025 (Agencywide Documents Access and Management System
[ADAMS] Accession No. ML25338A210), Framatome, Inc. (the applicant) submitted an amendment request to revise the Certificate of Compliance (CoC) No. 9372 for the Model No.
TN-B1 packaging.
The applicant requests to broaden the range of acceptable material specifications that can be used for stud bolts welded inside the packaging ensuring alignment with maintenance activities previously conducted on three TN-B1 transport packaging. The following drawings referenced in CoC Section 5a (3) have been updated to address this request.
FS1-0042698, Rev. 2.0, TNB1 Outer Container Main Body Assembly Licensing Drawing.
FS1-0042703, Rev. 2.0, TNB1 Outer Container Main Body Assembly Licensing Drawing.
The NRC staff reviewed the applicants request and found that the package meets the requirements of Title 10 of the Code of Federal Regulations (10 CFR) Part 71.
EVALUATION The applicant requested to update the following drawing numbers to allow a wider range of material specifications for M6 x 15L stud bolts specified as SUS304 stainless steel.
FS1-0042698, Rev. 1, Item 31, to include the option of using either SUS304 or SUS302 stainless steel bolts for M6 x 15L stud bolts.
FS1-0042703, Rev. 1, Item 13, to include the option of using either SUS304 or SUS302 stainless steel bolts for M6 x 15L stud bolts.
This revision aligns with prior maintenance activities performed on three TN-B1 packaging.
Background:
In October 2025, the applicant internal investigation determined that three TN-B1 packaging included a maintenance-replaced stud bolt (items M6 x 15L) that did not meet the required SUS304 stainless steel grade as specified in drawing referenced in CoC No. 9372. The applicant reported this finding to the NRC in accordance with 10 CFR 71.95 reporting requirements (ADAMS Accession No. ML25325A204).
The applicant stated that the three TN-B1 packaging with serial numbers RA-039, RA-086, and RA-142 had at least one stub bolt replaced with the same size but made of Type 302 stainless steel instead of the specified Type 304 stainless steel between July 2020 through August 2025.
The staff reviewed the TN-B1 safety analysis report (SAR), FSI-0014159, Rev. 11 and determined that the SAR discusses the use of bolts made of stainless steel without specifying Tyse 304 or 302 stainless steel.
Materials Evaluation:
In the 10 CFR 71.95 reporting, the applicant noted that Type 302 and Type 304 stainless steel have very similar chemical compositions. Type 302 may be produced with a chemical composition that falls within the Type 304 composition, effectively making the two stainless steels interchangeable.
The applicant stated that the primary difference between these two stainless steels lies in the carbon content, with Type 302 typically at 0.15% maximum, and Type 304 at a lower 0.08%
maximum. The higher carbon content in Type 302 increases tensile strength and hardness compared to Type 304 but can increase the risk of sensitization during welding. For stud bolt applications, Type 302 would be the preferable material, with typically higher tensile and yield strength, given welding concerns are adequately addressed. Both Type 302 and Type 304 are austenitic stainless steels and are readily weldable using standard processes. The applicant provided an analysis of the heat inputs for stud welding for the packaging. The typical heat inputs are well below those needed to lead to material sensitization. As noted by the applicant, the low heat inputs used in the stud welding process also reduce the time at elevated temperature that in turn reduces the possibility for sensitization.
The staff reviewed the information provided by the applicant and confirmed the similarity in material compositions between Type 304 and Type 302 stainless steel with the key compositional difference being the increased carbon content of Type 302. The staff also reviewed the yield and tensile strength and ductility specifications for these stainless steels and determined that the minimum required properties for both alloys are identical. The staff evaluated the information provided by the applicant on the stud welding and determined that the heat input used in the stud welding process was sufficiently low to avoid sensitization of the Type 302 studs during welding.
Based on the discussion above, the staff concluded that Type 302 and 304 austenitic stainless steel can be used interchangeably without impacting the safe operation of this package.
The NRC staff reviewed the applicants request and found that the package meets the requirements of Title 10 of the Code of Federal Regulations (10 CFR) Part 71.
CONDITIONS The following Conditions have been modified in the certificate:
Condition No. 3(b) was modified to refer to the latest consolidated safety evaluation report.
Condition No. 5(a)(3) was revised to include the revised licensing drawings.
The Reference section of the certificate was updated to refer to the December 4, 2025, amendment request.
CONCLUSION Based on the statements and representations contained in the application, and the conditions listed above, the staff concludes that the design has been adequately described and evaluated, and the Model No. TN-B1 package meets the requirements of 10 CFR Part 71.
Issued with CoC No. 9372, Revision No. 6.