ML23193A545
| ML23193A545 | |
| Person / Time | |
|---|---|
| Site: | 07109390 |
| Issue date: | 07/19/2023 |
| From: | Storage and Transportation Licensing Branch |
| To: | NAC International |
| Shared Package | |
| ML23193A542 | List: |
| References | |
| EPID L-2022-LLA-0142 | |
| Download: ML23193A545 (4) | |
Text
Request for Additional Information Model No. OPTIMUS-L Transport Package Docket No. 71-9390 Revision No. 2 By letter dated November 2, 2022 (Agencywide Documents Access and Management System
[ADAMS] Accession No. ML22306A109), NAC International (NAC) submitted an application (ML22306A113) to allow for the transport of TRISO compacts in a new basket within the NAC Model No. OPTIMUS-L package.
This request for additional information (RAI) identifies information needed by the U.S. Nuclear Regulatory Commission staff (the staff) in connection with its review of the application.
Each individual RAI describes information needed by the staff to complete its review of the application and to determine whether the applicant has demonstrated compliance with the regulatory requirements of Title 10 of the Code of Federal Regulations (10 CFR) Part 71.
2.0 STRUCTURAL EVALUATION 2-1 Clarify the torque value for installation of the cask containment vessel port cover bolts in step 10, section 7.1.2 and step 7, section 7.3 of the safety analysis report (SAR).
Note 6 on drawing 70000.14-L510, sheet 1, currently states, Alternatively, ASME SA-320, Grade L7 or L43 alloy steel may be used for the port cover bolts (item 11).
When this alternative is used, lubricate the threads of item 11 and torque bolts to 45 +/- 3 IN-LB. The specified torque value of 15+/- 1 in-lbs in step 10, section 7.1.2 and step 7, section 7.3 of the SAR is not correct, if the alternate bolt material per note 6 on drawing 70000.14-L510, sheet 1 is used for the port cover bolts. The procedure needs to be in alignment with the specified requirements on the licensing drawing.
This information is needed to determine compliance with 10 CFR 71.107(a).
2-2 Justify the acceptability of the seal weld as an alternate to the complete joint penetration (CJP) welds per note 11 on drawing 70000.14-L541 and note 9 on drawing 70000.14-L542 or remove these notes permitting an alternate seal weld.
Note 11 on drawing 70000.14-L541, revision 1P, sheet 1, and note 9 on drawing 70000.14-L542, revision 1P, sheet 1, are added to permit a seal weld as an alternate weld to the specified CJP weld of the Outer Package Base and Lid inner shell. Per American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (BPVC) section IX, the definition of seal weld is, any weld designed primarily to provide a specific degree of tightness against leakage, which may not be the equivalent of a CJP weld.
This information is needed to determine compliance with 10 CFR 71.31(b).
2-3 Clarify section A-A on drawing 70000.14-L561 revision 0P and provide additional dimensions and/or details of Item 1, bottom plate of the basket to identify the recessed extent of the bottom plate of the basket.
Enclosure
It is not clear from section A-A which two components are being welded. For item 1, only the overall thickness dimension is provided, and no other dimensions or details are provided. The pictorial configuration of item 1 shown on the drawing suggests that part of the plate under the fuel tubes area has a reduced thickness. Without any additional details, the item 1 configuration cannot be determined from this drawing.
This information is needed to determine compliance with 10 CFR 71.31(b), 71.71 and 71.73.
2-4 Provide the end drop evaluation for the bottom plate of the basket in section 7.0 of the calculation 70000.14-2108, revision 0, using the recessed bottom plate (i.e., with the reduced thickness - see RAI 2-3) under the fuel tubes area, or revise the plate configuration on the drawing to be consistent with the current evaluation.
Section 7.0, END DROP EVALUATION of the calculation 70000.14-2108 states the following in the first paragraph: During a bottom end drop, the tubes only apply a bearing load to the basket bottom plate. If the plate is recessed, as pictorially depicted on the drawing, the bottom plate carries the end drop load from the fuel tubes and self-weight in bending, which has not been analyzed.
This information is needed to determine compliance with 10 CFR 71.71 and 71.73.
2-5 Add a requirement for coating the GEO basket weldment carbon steel on drawing 70000.14-L561, revision 0P.
In section 12.2.5 and elsewhere in the SAR, electroless nickel plating of the carbon steel GEO basket weldment has been credited for corrosion protection. However, no such requirement for coating of carbon steel is specified on the GEO basket weldment drawing. The configuration on the licensing drawing needs to be in alignment with the evaluations contained in the SAR.
This information is required to determine compliance with 10 CFR 71.43(d) and 71.107(a).
2-6 Provide reference No. 14 and 22 used in section 6.3.2 and 7.4 of the calculation 70000.14-2108, revision 0 for TRISO Compacts evaluation.
Reference 14, Compact Details, CUI, NAC Document 50065-DI-01 and reference 22, BWXT Surrogate Mechanical Testing Results- 8-9-22 are used to obtain compact details and to establish TRISO compacts compressive strength, respectively. This information is requested to confirm that the compacts and its internal (e.g., graphite matrix) remain intact during the normal conditions of transport (NCT) and hypothetical accident conditions (HAC) drop scenarios as assumed in the criticality analysis in SAR section 6.9. If the compacts and graphite matrix fail and reconfigure as a result of drop tests, then the fissile material can relocate within or external to the basket tubes that hold the compacts, which is an unanalyzed condition. Note that the criticality analysis in section 6.9 of the SAR assumes that the TRISO compacts and graphite matrix are intact after the NCT and HAC tests.
This information is needed to determine compliance with 10 CFR 71.55 and 71.59.
3.0 THERMAL EVALUATION 3-1 Provide in the SAR the minimum and maximum allowable temperatures of the GEO assembly components so that a comparison with calculated package temperatures during NCT and HAC can be performed and to confirm there is no degradation of components.
SAR section 1.1 indicated that the TRISO contents GEO assembly is new for the amendment request. Drawing No. L560 indicated that the GEO assembly, which holds the TRISO compact content, can include polymer adhesive and polymer spacers.
Polymers have the potential for undergoing thermal degradation depending on their properties. The SAR did not list minimum and maximum allowable temperatures for the GEO assembly, including the polymer adhesive and polymer spacers.
This information is needed to determine compliance with 10 CFR 71.33.
3-2 Clarify that the numerical thermal model temperatures and the corresponding curves mentioned in SAR section 3.5.2.4 are bounding for decay heat content within local secondary containers.
SAR section 3.3 discussed the numerical modeling features from which the air temperature as a function of decay heat curves were generated. Since the curves described in SAR section 3.5.2.4 propose to use lower temperatures (for lower decay heats) when calculating hydrogen concentration (which is a function of temperature), it is important to ensure that the model results are bounding, recognizing that a high decay heat content locally within a small volume inside the Cask Containment Vessel (i.e.,
locally high decay heat density that may occur within discrete secondary containers discussed in SAR section 1.2.2.1), may not be represented by the bulk temperature of the models averaging assumption.
This information is needed to determine compliance with 10 CFR 71.43(d).
4.0 CONTAINMENT EVALUATION 4-1 Clarify in the SAR that the TRISO content is commercial grade uranium with type A activity and, if not, specify the concentrations of the radionuclides and the TRISO contents activity.
Although SAR section 5.2 indicated that TRISO content is fresh, unirradiated fuel and contains no significant radionuclide inventory, certain unirradiated fuel can contain radionuclide contaminants (e.g., Np-237) with slight concentrations that result in type B activity.
This information is needed to determine compliance with 10 CFR 71.33.
4-2 Provide, in the SAR, specifications for the TRISO content and clarify that the TRISO content, which includes a graphite matrix, maintains structural integrity during HAC tests.
Although there was a stress calculation for the TRISO compact structure during a particular end drop, there were no details on the structural integrity of the TRISO content (which includes a graphite matrix according to SAR section 6.9.2) during HAC tests.
In addition, there were no specifications that define the TRISO content, including geometry and dimension details, drawings, and structural properties such as toughness and fracture qualities.
This information is needed to determine compliance with 10 CFR 71.33.