ML23074A252
| ML23074A252 | |
| Person / Time | |
|---|---|
| Site: | 07201031 |
| Issue date: | 03/29/2023 |
| From: | Nishka Devaser Storage and Transportation Licensing Branch |
| To: | Baldner H NAC International |
| References | |
| EPID L-2022-LLA-0145 | |
| Download: ML23074A252 (1) | |
Text
March 29, 2023 Heath Baldner Licensing Manager NAC International 3930 East Jones Bridge Road, Suite 200 Norcross, GA 30092
SUBJECT:
APPLICATION FOR AMENDMENT NO. 13 TO THE MODEL NO.
MAGNASTOR STORAGE CASK - REQUEST FOR ADDITIONAL INFORMATION
Dear Heath Baldner:
By letter dated July 13, 2022 (Agencywide Documents Access and Management System
{ADAMS} Accession No. ML22194A908), as supplemented on October 13, 2022, and November 30, 2022 (ADAMS Accession Nos. ML22287A038 and ML22321A269, respectively),
NAC International (NAC) submitted an application in accordance with Title 10 of the Code of Federal Regulations Part 72 to amend Certificate of Compliance No. 1031 for the Model No. MAGNASTOR storage system to add the remaining damaged core material from the Three Mile Island Unit 2 (TMI-2) reactor that experienced the March 28, 1979, reactor accident new damaged fuel basket and a shorter version of the canister, transfer cask, and storage cask.
This request for additional information identifies information needed by the U.S. Nuclear Regulatory Commission staff in connection with its review of the application. Each question describes information needed by the staff for it to complete its review of the application and to determine whether the applicant has demonstrated compliance with regulatory requirements.
In order to complete our technical review on schedule, your response should be provided within 60 days from the date of this letter. If you have any questions regarding this matter, I may be contacted at (301) 415-5196.
Sincerely, Signed by Devaser, Nishka on 03/29/23 Nishka Devaser, Project Manager Storage and Transportation Licensing Branch Division of Fuel Management Office of Nuclear Material Safety and Safeguards Docket No. 72-1031 EPID L-2022-LLA-0145
Enclosure:
Request for Additional Information
Request for Additional Information Docket No. 72-1031 Certificate of Compliance No. 1031 Model No. MAGNASTOR Storage System Amendment No. 13 By letter dated July 13, 2022 (Agencywide Documents Access and Management System
{ADAMS} Accession No. ML22194A908), as supplemented on October 13, 2022 and November 30, 2022 (ADAMS Accession Nos. ML22287A038 and ML22321A269, respectively),
NAC International (NAC) submitted an application in accordance with Title 10 of the Code of Federal Regulations Part 72 to amend Certificate of Compliance (CoC) No. 1031 for the Model No. MAGNASTOR storage system to add the remaining damaged core material from the Three Mile Island Unit 2 (TMI-2) reactor that experienced the March 28, 1979, reactor accident new damaged fuel basket and a shorter version of the canister, transfer cask, and storage cask.
The questions below describe information needed by the staff for it to complete its review of the application and to determine whether the applicant has demonstrated compliance with regulatory requirements.
Chapter 3: Structural Evaluation RAI 3-1. CC6 Concrete Cask Modification - The staff requires a summary of the load demands on the elements of the cask and the corresponding capacities or margins to the reduced strength of the concrete.
The concrete compressive strength for the reinforced concrete cask, CC6 of MAGNASTOR design, is modified by Amendment No. 13 to the MAGNASTOR final safety analysis report (FSAR). The required concrete compressive strength of the cask concrete is reduced. However, the loading demands on the cask, which are defined by the operating processes, environment, and load handling equipment, remain the same. Understanding of the demand verses the capacity of the cask elements is essential in establishing reasonable assurance that the design of the cask elements provide an adequate margin of safety.
This information is required to demonstrate compliance with 10 CFR 72.122.
RAI 3-2. CC6 Concrete Density - Explain the process which ensures that the density of the concrete will remain the same even after the compressive strength of the concrete is reduced.
Change in concrete compressive strength is achieved by an appropriate change in the design of the concrete mix. Even though there is no direct relation between concrete compressive strength and density, changing the design of the mix has the potential for affecting the density of concrete. The density of concrete has short- and longer-term impacts. Short term impacts affect shielding and thermal characteristics and longer-term impacts are on aging degradation.
This information is required to demonstrate compliance with 10 CFR 72.24(4)(d) and (e).
RAI 3-3. Safety Classification of Structures Systems and Components SSCs) - Provide a safety classification for the waste basket liner (WBL), segmented tube assembly Enclosure
(STA) and debris material container DMC) and include these in the FSAR safety classification table.
The WBL containing fuel bearing material (FBM) is lifted into the transportable storage canister (TSC) using the lifting handles. In this, situation it is the sole container of the FBM radioactive material. Therefore, a safety designation is required and an analysis for safety during the lift needs to be performed. For the STA and DMC, NAC has identified these as assisting with the FBM loading, placement and retention, but without any specific safety functions. If so, they should be classified as such in the safety classification table. A note needs to be added that these elements have only non-structural functions.
This information is required to demonstrate compliance with 10 CFR 72.24(4)(d)(2).
RAI 3-4. Closure Lid Thickness Reduction - Provide a summary table with the analyzed demands and margins of the 5-inch closure lid for the TSC.
Amendment No. 13 reduces the TSC closure lid thickness from 9 inches to 5 inches to increase the FBM carrying capacity of the TSC. This change in the lid thickness results in a change in the stress level within the lid when subject to the different environmental conditions, handling, and any internal pressure change.
This information is required to demonstrate compliance with 10 CFR 72.24(4)(d)(1).
RAI 3-5. Elimination of hydrostatic testing for the new configuration in Amendment No. 13
- Provide a table summarizing the evaluation of the closure weld of the lid, to establish the minimum weld size required for the loading demands.
In Amendment No. 13, NAC has opted to eliminate the need for a hydrostatic test to demonstrate that the weld has sufficient margin against failure. To have reasonable assurance on the adequacy of the margin in the weld design the staff needs to know the minimum computed weld size and the provided weld size along with full compliance with required NDE and required documentation.
This information is required to demonstrate compliance with 10 CFR 72.122.
Chapter 4: Thermal Analysis Evaluation RAI 4-1. Provide justification/explanation for the exclusion of the STA, dunnage, and WBL in thermal evaluations of normal, off-normal, and accident conditions of storage.
The applicant stated, in FSAR section 1.3.1.1, that a WBL is used to replace the fuel basket structure for storage of FBM. FBM is permitted to be loaded loose into the WBL or within other internal structures (dunnage) loaded into the WBL.
WBL internal structures such as the STA or the DMC are handling/placement devices and are not credited within the safety evaluations.
The applicant needs to justify/explain that exclusion of the STA, dunnage, and WBL in the modeling is credited for thermal analyses of normal, off-normal, and accident conditions of storage.
The staff needs this information to determine compliance with 10 CFR 72.236(f).
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Chapter 8: Materials Evaluation RAI 8-1. Physical and Chemical Form of Filter Media: Please supplement the application to specify the physical and chemical form of the filter media associated with the FBM contents by including the following information:
A) Describe the components, parts, and/or materials that constitute the filter media.
B) Describe the physical and chemical form of the filter media (e.g., solids, liquids, gases, metallic materials and items, organic compounds, hydrogenous materials, water, etc.).
C) Describe how the filter media originated and are associated with FBM.
For example, address whether the filter media were used during reactor operation; during the reactor accident; or whether they were used to facilitate removal of the damaged fuel and/or FBM from the reactor during the post-accident cleanup and decontamination.
D) Clarify whether the filter media are categorized as part of the FBM contents; whether they are considered separate from the FBM contents; whether they contain or are attached to the FBM contents; or whether they are categorized as WBL-internal dunnage components similar to the STA and DMC.
E) Clarify whether the filter media to be stored inside the FBM TSC and WBL are authorized for storage only with FBM or whether they may also be stored with actual intact spent fuel rods or segments of spent fuel rods.
FSAR section 1.4.2 states that filter media containing FBM or used fuel
((emphasis added)) may be loaded into the FBM TSC provided the filter media is metallic. The application then states that non-metallic media ((emphasis added))
may be permitted subject to gas generation limitations. The application states that filter media may account for potential sources of gas, in particular hydrogen, as a result of water retention. The application states that any potential retention must be accounted for within total allowed hydrogen generation; maximum hydrogen generation during storage and transportation will not exceed the lower explosive limit (4 percent molar volume). FSAR section 7.2.2 states that a limited quantity of moisture may remain trapped within the FBM, or within the filter media, post vacuum drying.
Based on review of this description of filter media, the staff identified that physical and chemical form of the filter media contents are not sufficiently described in the application such that staff can adequately evaluate physical and chemical stability of the filter media and their chemical compatibility with the FBM and the TSC internal components (WBL and dunnage) in the nitrogen gas environment.
The NRC staff is requesting this information to verify that the application includes an adequate description of the contents such that the staff can fully evaluate the physical and chemical stability of the filter media and FBM contents and verify that there will be no adverse reactions amongst the FBM and filter media contents, or between the contents and the TSC internal components (WBL and dunnage) in the nitrogen gas environment. The staff determined that this information is needed to evaluate the compliance of the MAGNASTOR FBM 3
storage system with the regulatory requirements of 10 CFR sections 72.120(d) and 72.236(h).
RAI 8-2. Chemical Reactions in the Nitrogen Gas Environment: Considering the elemental and molecular contents of the FBM and filter media, please justify why nitrogen is an acceptable environment for the interior of the cask and provide information to demonstrate that the use of nitrogen as the TSC fill gas will not result in adverse chemical reactions with and amongst the FBM and filter media contents inside the WBL.
FSAR section 1.4.2 of the application includes a description of the physical and chemical form of the FBM contents and describes FBM as consisting of components or pieces of components associated with reactor operations that have been contaminated by spent nuclear fuel and/or the associated isotopes of spent nuclear fuel, including fission product contamination. The detailed description of the FBM in FSAR section 1.4.2 addresses a number of potential metallic materials, non-metallic materials, organic compounds, and hydrogenous compounds that may be intermixed with fission products and other radioisotopes from damaged fuel and activated non-fuel materials. The application states that non-metallic FBM may be loaded into the FBM TSC provided that maximum hydrogen generation during storage and transportation will not exceed the lower explosive limit (4 percent molar volume) and system pressure is evaluated as acceptable. As addressed above for Materials Review RAI 8-1, the application also includes some description of filter media associated with the FBM; however, per RAI 8-1, the staff identified that the physical and chemical form of the filter media are not sufficiently described in the application.
FSAR section 8.10.1 of the application discusses the interior storage environment inside the sealed TSC. The TSC containing FBM is to be backfilled with nitrogen gas. This section of the application indicates that nitrogen backfill gas displaces oxygen inside the TSC, similar to how helium is used in backfilling the TSC. However, the application does not include specific information that demonstrates that adverse chemical reactions in the nitrogen environment are not a concern for the chemical elements and compounds that constitute the FBM and filter media. The staff noted that, while nitrogen gas is sufficiently inert for many applications, unlike helium gas it cannot be assumed to be completely unreactive when used as a cover gas for all types of contents. Therefore, the staff determined that additional information is needed to evaluate the chemical stability of FBM and filter media contents in the nitrogen gas environment.
The NRC staff is requesting this information to verify that the application includes an adequate description of the contents such that the staff can fully evaluate the physical and chemical stability of the FBM and filter media contents and verify that there will be no adverse reactions amongst the FBM and filter media contents, or between the contents and the TSC internal components (WBL and dunnage) in the nitrogen gas environment. The staff determined that this information is needed to evaluate the compliance of the MAGNASTOR FBM storage system with the regulatory requirements of 10 CFR sections 72.120(d) and 72.236(h).
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Chapter 9: Operating Procedures Evaluation RAI 9-1. Provide information for justification on using heated nitrogen in the vacuum drying.
The applicant performed thermal analyses of vacuum drying using non-heated nitrogen gas in the TSC and presented the maximum temperatures in FSAR table 4.12-2 and then notes, in step 56 of FSAR section 9.7.1, that vacuum drying efficiency may be improved by injection of heated nitrogen followed by re-establishment of vacuum condition. This process may be repeated as needed.
Injection of heated nitrogen in loading operations may result in the temperatures greater than the maximum temperatures, as shown in FSAR table 4.12-2, which were calculated assuming non-heated nitrogen for vacuum phase. The applicant may need to setup a temperature limit of heated nitrogen and limit the number of repeated cycles.
The staff needs this information to determine compliance with 10 CFR 72.236(f).
RAI 9-2. Provide information to items (A), (B) and (C) below to ensure safe storage of the FBM contents in MAGNASTOR TSC.
The applicant stated, in FSAR section 1.4, that non-metallic FBM may be loaded into the FBM TSC provided maximum hydrogen generation during storage and transportation will not exceed the lower explosive limit (4% molar volume). Any potential retention must be accounted for within total hydrogen generation.
The applicant described, in FSAR section 9.7, that to ensure dryness of FBM TSC during vacuum drying operation, (1) FBM TSC is evacuated to less than 10 torr at the end of 10 minutes (a minimum period of 10 minutes) to ensure the FBM TSC cavity is dry of free water and (2) upon satisfactory completion of the dryness verification, the FBM TSC is further evacuated to less than 3 torr (without providing the required time period).
A) Provide self-ignition points and/or melting points of the FBM contents (e.g., contaminated FBM, non-metallic FBM, activated non-fuel materials, etc.) to ensure no significant combustion, reaction, or activation under storage of normal, off-normal and accident conditions of storage.
B) The staff recognizes that the decay heat of the FBM TSC is bounded by the spent fuel TSC which was approved by the NRC, therefore the FBM TSC may be bounded by the spent fuel TSC too in hydrogen generation.
However, given that the non-metallic FBM/media may be included within the contents of the FBM DSC, the applicant needs to provide information or evaluation (e.g., amount and G-value of the non-metallic materials) to demonstrate that hydrogen generation of the FBM TSC would be limited to less than 4%.
C) Clarify whether a minimum period (e.g., greater than 30 minutes) is required to maintain a vacuum pressure less than 3 Torr for dryness verification of the FBM TSC?
The staff needs this information to determine compliance with 10 CFR 72.236(h).
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RAI 9-3. Correct step references in section 9.7.1 to ensure that the user can perform the operational steps as directed.
Many of the step references in section 9.7.1 refer the user to incorrect steps that cannot be performed as directed. The following is a list of examples but is not all inclusive. All step references should be reviewed and corrected as necessary.
- a. Steps 69 and 70 references in the step 26 note, which do not refer to ACWS or alternative annulus flush/circulating water system actions.
- b. Step 60 reference in the step 49 note, nitrogen backfill is not performed at step 60.
- c. Step 70 reference to table 9.1-1, which does not list bolt torque values.
This information is needed to determine compliance with 10 CFR 72.234 and 72.236.
RAI 9-4. Modify the note in step 58 and action in step 64 to ensure that there is only one step to install and weld the inner port cover on the drain port opening.
This information is needed to determine compliance with 10 CFR 72.234 and 72.236.
RAI 9-5. Include a step or direction to the user in section 9.7.5 to provide the option to use ACWS or R-ACWS or remove the reference to ACWS and R-ACWS in step 29.
Step 29 directs the user to terminate ACWS or R-ACWS, if used, however, the user is not directed or given the option in the section 9.7.5 operational sequence to install and use the ACWS or R-ACWS system.
This information is needed to determine compliance with 10 CFR 72.234 and 72.236.
Observations Operating Procedures OBS 9-1. 9.7.1, step 63: remove each of as only the vent port inner cover is being referred to in this sentence.
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Ltr ML23074A252
- via email OFFICE NMSS/DFM/STLB NMSS/DFM/CTCFB NMSS/DFM/STLB NRR/DEX/ESEB NAME NDevaser ND FChang FC WWheatley WW SSamaddar SS DATE Mar 16, 2023 Mar 16, 2023 Mar 20, 2023 Mar 16, 2023 OFFICE NMSS/DFM/IOB NMSS/DFM/IOB NMSS/DFM/CTCFB NMSS/DFM/MSB NAME JTapp JT ARivera-Varona AR JPiotter JP TBoyce TB DATE Mar 17, 2023 Mar 23, 2023 Mar 20, 2023 Mar 21, 2023 OFFICE NMSS/DFM/CTCFB NMSS/DFM/STLB NRR/DNRL/NVIB* NMSS/DFM/STLB NAME DMarcano DM YDiaz-Sanabria YD CSydnor CS NDevaser ND DATE Mar 27, 2023 Mar 27, 2023 Mar 29, 2023 Mar 29, 2023