ML20344A353

CoC 1027 (TN-68) Renewal - Enclosure 1

ML20344A353
Person / Time
Site:	07201027
Issue date:	12/10/2020
From:	Christian Jacobs Storage and Transportation Licensing Branch
To:	Narayanan P TN Americas LLC
CJJacobs - NMSS/DFM/STL - 301.415.6825
Shared Package
ML20344A351	List: ML20344A352 ML20344A353
References
CAC 001028, EPID L-2020-RNW-0014
Download: ML20344A353 (5)

Text

Enclosure 1 Request for Additional Information (non-proprietary)

By letter dated April 9, 2020, and supplemented July 29, 2020, TN Americas LLC submitted an application to the U.S. Nuclear Regulatory Commission (NRC) for renewal of the TN-68 Dry Storage Cask, Certificate of Compliance (CoC) No. 1027, pursuant to the requirements of Part 72 of Title 10 of the Code of Federal Regulations (10 CFR).

This request for additional information (RAI) identifies additional information needed by the NRC staff in connection with its review of this renewal application. Each RAI below describes information needed by the staff to complete its review of the subject application.

RAI-1. Provide additional information to justify the use of interim staff guidance (ISG)-2 Revision 2 (ML16117A080) to define the basis of the retrievability function of the TN-68 Cask, which differs from the approved design bases of the TN-68 casks.

Section 2.2 of the CoC No. 1027 renewal application states, The retrievability safety function is based on the ability to remove a cask loaded with spent fuel assemblies from its storage location; i.e., option C in Revision 2 of Interim Staff Guidance (ISG) 2. However, TN-68 final safety analysis report (FSAR) Chapter 14, identifies 2 options for decommissioning, which appears to be inconsistent with the reference in Section 2.2 to ISG-2 Revision 2. Based on the information included in TN-68 FSAR Chapter 14, it appears that the design bases for the TN-68 system would be ISG-2 Revision 0 (ML092800367) dated October 6, 1998.

The staff notes that ISG-2 Revision 2 defines ready retrieval as the ability to safely remove the spent fuel from storage for further processing or disposal, and provided three options for meeting the retrievability requirement. ISG-2 Revision 2 did not change the licensing bases for storage systems that were already approved.

This information is needed to determine compliance with 10 CFR 72.236(m) and 72.240(c).

RAI-2 (PROP) - SEE ENCLOSURE 2 RAI-3. Provide additional information on the end of life cavity pressure analysis provided in the CoC No. 1027 renewal application Section 3A.6:

1. An analysis to account for the effects of the TN-68 leak rate on the end of life cavity pressure analysis or a justification for not considering the cask leak rate.

2. A technical justification or reference for the average cavity gas temperature at the end of 60 years of storage, which was determined to be 47.5 °F (507 °R) based on a decay heat value of 8.42 kW and an ambient temperature of 20 °F.

The evaluation provided in the CoC No.1027 renewal application Section 3A.6 accounts for the minimum average daily ambient design temperature for the TN-68 cask but does not include an assessment of the TN-68 leak rate. The staff notes that the TN-68 is not leak tight in accordance with ANSI N14.5 and the technical specifications for the TN-68 system include a leak rate less than 105 cm3/second. In addition, the staff notes that the similar calculation for the CoC No. 1021 renewal application assumes a cavity temperature 20°F (440°R).

This information is needed to determine compliance with 10 CFR 72.240(c).

RAI-4. Provide the following additional information on Radiation Monitoring for the TN-68 Cask Aging Management Plan (AMP) and update the AMP as necessary. Because the shielding material is made of borated polyester and polypropylene, there is the possibility that heat from spent fuel coupled with age may degrade this material and reduce its shielding effect. The applicant proposes to use radiation monitoring at the perimeter fence to ensure that the shielding material maintains its integrity.

Please provide:

1. Parameters Monitored or Inspected: A description of how the parameters monitored will be capable of identifying degradation or potential degradation before a loss of intended function for a specific cask considering that the number of TN-68 casks which may be loaded and placed on the independent spent fuel storage installation (ISFSI) storage pad can vary with time.

2. Detection of Aging Effects: The technical basis to show that detection of gamma and neutron radiation by the use of thermoluminescent dosimeters (TLDs) at the ISFSI perimeter fence has sufficient resolution to identify degradation of the shielding effectiveness for the individual casks. Section 4.3.4.2 of the renewal application states, Detection of gamma and neutron radiation is accomplished by the placement of the TLDs at the ISFSI perimeter fence, or between the ISFSI and locations used to show compliance with 10CFR20.1301 and 10CFR72.104. While the TLDs may not be capable of detecting all neutrons (i.e., the very high energy neutrons) they are effective in detecting adverse trends in neutron dose rates.

3. Detection of Aging Effects: Identify the personnel qualifications for the staff that evaluate the radiation monitoring results.

4. Acceptance Criteria: The acceptance criteria (e.g., level of increase) that will be used to determine the annual upward increasing trend in neutron or gamma quarterly TLD readings at the ISFSI perimeter fence that indicates a loss of intended function of the shielding, including a description of how the criteria account for decay of the spent fuel source term and consideration for the use of the TN-68 system at an operating reactor or ISFSI where the number of storage casks is increasing with time.

5. Operating Experience: A summary of the available operating experience for similar cask designs such as those used at the North Anna ISFSI and the Prairie Island ISFSI.

Include a description of how the TLD data trends at the Prairie Island ISFSI with the cask survey results described in the Prairie Island ISFSI AMP (ML15285A007) will be considered in the Operating Experience AMP element.

This information is needed to determine compliance with 10 CFR 72.240(c).

RAI-5. Provide the following additional information on Visual Inspection for the TN-68 Cask AMP and update the AMP as necessary.

1. Parameters Monitored or Inspected: Identify the specific parameters that will be monitored or inspected and describe how those parameters will be capable of identifying loss of material due to general, pitting, crevice, and galvanic corrosion of aluminum.

2. Detection of Aging Effects: Identify the code or standard used to conduct the visual inspections. Describe the technical basis for the code or standard used for the visual inspection and explain how the application of the code or standard selected will have sufficient resolution to identify a defect dimension necessary to assess the extent of aging or quantify the loss of material. Justify the use of personnel that are not qualified to perform non-destructive examination (NDE) to conduct visual inspections for the TN-68 Cask AMP.

3. Monitoring and Trending: Describe what data will be collected and how the data collected will be evaluated. Includes a description of how the inspection results will be evaluated against the acceptance criteria.

4. Acceptance Criteria: Provide quantitative acceptance criteria for the evaluation of the loss of material due to general, pitting, crevice, and galvanic corrosion for the steel, stainless steel and aluminum components of the TN-68 cask. The description of the acceptance criteria should identify the extent of aging that prompts corrective actions to ensure that the structures, systems and components (SSC) intended functions and the approved design bases are maintained during the period of extended operation.

5. Operating Experience: Explain how the aging related effects identified in the operating experience review were incorporated into the TN-68 Cask AMP.

This information is needed to determine compliance with 10 CFR 72.240(c).

RAI-6. Provide the following additional information for the ISFSI Storage Pad AMP and update the AMP as necessary.

1. Parameters Monitored or Inspected: Clarify the statement in CoC renewal application Section 4.4.3 Storage Pad AMP which states, The inaccessible areas of the storage pad that include below-grade surfaces off the storage pad.

2. Parameters Monitored or Inspected and Acceptance Criteria: Explain how ACI 349.3R is used to inspect concrete to assure that the thermal function will be maintained.

Section 2.3.3 of the renewal application states, However, a portion of the pad is included in the thermal models. Therefore, failure of the pad could affect the heat removal capability of the system, i.e., prevent fulfillment of an intended safety function.

The staff notes that ACI 349.3R-2018 is focused on structural performance and states, The purpose of this report is to provide the owner, owners engineering staff, consultants, and others with an appropriate procedure and background for examining concrete structural performance and taking appropriate actions based on observed conditions. Therefore, it is not clear to the staff how the parameters monitored or inspected, and acceptance criteria based on ACI 349.3R-2018 will be applied to assure that the heat removal capability of the pad is maintained throughout the period of extended operation.

3. Detection of Aging Effects: Clarify the ACI 349.3R-2018 section referenced in the Storage Pad AMP Section 4.4.4. The section states Direct visual inspections utilizing ACI-349.3R [4-3], Section 3.5.1 are to be conducted of the above-grade portions of the concrete storage pad, allowing for detection of aging effects from Table 4-2. The staff notes that ACI 349.3R-2018 Section 3.5 is the Evaluation procedure document and there is no Section 3.5.1. It appears that the callout should refer to ACI 349.3R Section 3.6.1 which describes the visual inspection techniques and the inspection documentation.

4. Detection of Aging Effects: Describe the technical basis for using only the results of groundwater sampling to evaluate the degradation of the below-grade portion of the concrete pad. The staff notes that ACI 349.3R-2018 Section 3.4Periodic evaluation states, To verify that the selected sample areas are, in fact, representative of worse case conditions, complementary sample area inspections should be made in areas where little or no degradation is expected. For example, structures primarily located below grade might not be readily accessible for evaluation but could be exposed to an aggressive environment. Measures can be implemented that establish the condition of these structures through determination of soil and groundwater chemistry and local inspection during opportune soil excavations, such as during new equipment installation.

While such efforts are indirect and not comprehensive, they can be used to characterize environmental exposure conditions and their effects to assist in prioritizing further evaluation efforts.

5. Detection of Aging Effects: Clarify personnel qualifications for staff conducting inspections and indicate whether the guidance in ACI 349.3R Section 7 regarding personnel qualification will be required.

This information is needed to determine compliance with 10 CFR 72.240(c).

RAI-7. Provide the following additional information in Table A-2.

1. Scope of program: Include the aging effects and mechanisms that will be managed via the TN-68 AMP into the Scope of program in Table A-2.

2. Parameters Monitored or Inspected: Identify the specific parameters that will be monitored or inspected and describe how those parameters will be capable of identifying loss of material due to general, pitting, crevice, and galvanic corrosion of aluminum.

3. Detection of Aging Effects: Identify the code or standard used to conduct the visual inspections. Justify the use of personnel that are not qualified to perform NDE to conduct visual inspections for theTN-68 Cask AMP. Identify the personnel qualifications for the staff that evaluate the radiation monitoring results.

4. Monitoring and Trending: Describe what data will be collected and how the data collected will be evaluated. Include a description of how the inspection results will be evaluated against the acceptance criteria.

5. Acceptance Criteria: Provide quantitative acceptance criteria for the evaluation of the loss of material due to general, pitting, crevice, and galvanic corrosion for the steel, stainless steel and aluminum components of the TN-68 cask. The description of the acceptance criteria should identify the extent of aging that prompts corrective actions to ensure that the SSC intended functions and the approved design bases are maintained during the period of extended operation.

6. Include the reference to 4-2. Nuclear Energy Institute (NEI) 14-03, Format, Content, and Implementation Guidance for Cask Storage Operations-Based Aging Management, Revision 2, Nuclear Energy Institute, December 2016.

The NEI 14-03 document contains guidance that is significant for the CoC users. The staff notes that only the information included in the CoC renewal application Attachment A will be incorporated into the updated final safety analysis report (UFSAR) and information with respect to the aging mechanisms and effects managed by the AMPs is considered necessary to ensure that general licensees implement and update, as necessary, AMPs to maintain their effectiveness.

This information is needed to determine compliance with 10 CFR 72.240(c).

RAI-8. Provide the following additional information in Table A-3.

1. Scope of Program: Include a description of the aging effects/mechanisms will be managed via this AMP.

2. Detection of Aging Effects: Clarify personnel qualifications for staff conducting inspections and indicate whether the guidance in ACI 349.3R Section 7 regarding personnel qualification will be required.

3. Include the references to:

4-2. NEI 14-03, Format, Content, and Implementation Guidance for Cask Storage Operations-Based Aging Management, Revision 2, Nuclear Energy Institute, December 2016.

4-3. American Concrete Institute, ACI-349.3R, Evaluation of Existing Nuclear Safety Related Concrete Structures, 2018 The NEI 14-03 document contains guidance that is significant for the CoC users. The ACI Code contains information relative to the inspection of the storage pad. The staff notes that only the information included in the CoC renewal application Attachment A will be incorporated into the UFSAR and information with respect to the aging mechanisms and effects managed by the AMPs is considered necessary to ensure that general licensees implement and update, as necessary, AMPs to maintain their effectiveness.

This information is needed to determine compliance with 10 CFR 72.240(c).

RAI-9. Provide the following additional information in Table A-4.

1. Detection of Aging Effects: Add the statement in the high Burnup (HBU) Fuel AMP which states, The program calls for monitoring cask internal temperatures during the drying process and while the cask is in storage on the ISFSI pad. Temperature is the key driver for hydride-induced embrittlement and thermal creep, or an equivalent. The staff notes that only the post storage inspection portion of the joint Electrical Power Research Institute (EPRI) and Department of Energy (DOE) HBU Dry Storage Cask Research and Development Project (HDRP) (EPRI 2014) was included in the detection of aging effects AMP element in Table A-4.

2. Incorporate the following references into Table A-4:

4-2. NEI 14-03, Format, Content, and Implementation Guidance for Cask Storage Operations-Based Aging Management, Revision 2, Nuclear Energy Institute, December 2016.

4-4. Electric Power Research Institute, High Burnup Dry Storage Cask Research and Development Project: Final Test Plan, Revision 0, DE-NE-0000593, February 27, 2014.

The references above (NEI 14-03 document and the EPRI HDRP Final Test Plan) contain guidance and technical information that is significant for the CoC users. The staff notes that only the information included in the CoC renewal application Attachment A will be incorporated into the UFSAR and information with respect to the aging mechanisms and effects managed by the AMPs is considered necessary to ensure that general licensees implement and update, as necessary, AMPs to maintain their effectiveness.

This information is needed to determine compliance with 10 CFR 72.240(c).