ML23146A142

Attachment 3 - Implementation of Topical Reports

ML23146A142
Person / Time
Site:	Holtec
Issue date:	05/26/2023
From:	Holtec
To:	Office of Nuclear Material Safety and Safeguards
Shared Package
ML23146A138	List: ML23146A139 ML23146A140 ML23146A141 ML23146A142
References
5014962
Download: ML23146A142 (12)

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Attachment 3 to Holtec Letter 5014962 1.0.3 Implementation of Topical Reports 1.0.3.1 Thermal Topical Report The NRC has reviewed and approved Topical Report HI-2200343-A [1.0.7]. This report outlines a methodology for developing heat load patterns for each canister. Throughout this FSAR, the areas where the topical report can be applied are identified. However, since the topical report itself is specifically focused on the thermal methodology, this section provides an outline of the approach for implementing that methodology. For additional clarity, a flowchart of the process is included in Figure 1.0.1.

Change Control The NRCs SER [1.0.8] explicitly lays out restrictions on the scope of the review for the topical report. Most notably, limitation 4.2 describes the model reviewed for the scope of the topical report as invariant. However, since this FSAR is subject to the provisions of 10CFR72.48, use of that topical report needs to address the change control process. Note that in all cases, the HI-STORM 100 system being considered must be one of the models listed in Appendix 1 of [1.0.8]

The following explains the steps in the flow chart in Figure 1.0.1 for implementation of the topical report

• Step 1: Site decides the existing CoC heat load patterns do not meet their needs, and develops a new pattern that would meet fuel loading needs

• Step 2: General Licensee and Holtec determine if the HI-STORM 100 system and contents being loaded matches the invariant model in the topical report [1.0.7]

o If yes, then proceed through the qualification process outlined in the topical report, ensure all topical report acceptance criteria (including all temperatures and pressures from Tables 2.1 and 2.2 of [1.0.7]) are met, and rejoin at Step 3 o If no, follow steps 2a through 2d

• Step 2a: Ensure that the variations from the topical report [1.0.7] invariant model (identified in Step 2) are acceptable without prior NRC approval o This process is identical to Holtecs existing 72.48 program and should be documented accordingly, which develops a 72.48 model for that variation o If the 72.48 process indicates that prior NRC approval is required, that application must be made and approved by the NRC prior to use of the HI-STORM 100 system. The topical report methodology [1.0.7] cannot be used until NRC approval is obtained.

• Step 2b: Once the variations have been determined to be acceptable without prior NRC approval under 72.48, the sites candidate heat load pattern should be evaluated in the 72.48 model, which is the thermal model with all 72.48 modifications applicable to the planned loaded canisters o The results of this calculation must show that all components have a lower temperature than the FSAR limits and pressures lower than the FSAR limits o The peak cladding temperature (PCT) from this analysis is then compared to the results from Step 2c HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 22C REPORT HI-2002444 1-6 Page 1 of 12

Attachment 3 to Holtec Letter 5014962

• Step 2c: The candidate heat load pattern is then fully qualified for use by evaluation in the Topical Report [1.0.7] invariant model o This evaluation must show ALL Topical Report [1.0.7] acceptance criteria are met, including all temperatures and pressures from Tables 2.1 and 2.2 of [1.0.7]

o This evaluation must show a higher PCT than Step 2b o If either of these conditions is not met, the candidate heat load pattern must be revised and Steps 2b and 2c are repeated. The original candidate heat load pattern is not eligible for loading.

• Step 2d: The temperature results from both Steps 2b and 2c are compared to the structural evaluations in the FSAR o If FSAR structural evaluations use temperatures that bound the calculated temperatures, no further structural evaluations are needed o IF FSAR structural evaluations use temperatures that do NOT bound the calculated temperatures, an additional 72.48 must be performed to demonstrate the new temperatures are acceptable without NRC approval If the structural evaluation changes are not acceptable under 72.48 than either the candidate heat load pattern must be changed or application made to the NRC and NRC approval obtained prior to use of the topical report

[1.0.7] methodology

• Step 3: Once all the items and acceptance criteria in Step 2a through 2d are satisfied -

document the evaluation performed in Step 2c (candidate heat load pattern in invariant model) in sites qualification report and referenced as appropriate in the general licensees 72.212 report. Sites can use Section 5.0 of HI-2200343-A as an example format for this qualification report.

• Step 4: Site chooses fuel to meet the qualified heat load pattern, confirming that the fuel also meets other CoC requirements, such as (but not limited to) fuel types and FQTs (see below shielding discussion)

• Step 5: Site ensures loading procedures have the accurate restrictions for:

o Helium Backfill - HI-2200343-A Section 2.3.6 o Time to boil - HI-2200343-A Section 2.3.8 o Duct Blockage allowable clearance time or temperature monitoring limit - HI-2200343-A Section 2.3.12 Shielding The fuel qualification limits for burnups, enrichments and cooling times (BECTs) are independent of the fuel decay heat limits, and any assembly has to meet both the applicable BECT limits, and any decay heat limit developed through the application of the Topical Report.

No changes are made for now to these BECT limits, and no additional dose calculations are needed for the existing limits. Hence there are no new shielding analyses needed as a consequence of introducing the Topical Report. For further discussions and explanations see the following paragraphs.

Independence of BECTs and decay heat limits Earlier revisions of this FSAR included an explicit link between BECTs and decay heat limits, and this also impacted the way the dose analyses were performed. The link was specified in the HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 22C REPORT HI-2002444 1-7 Page 2 of 12

Attachment 3 to Holtec Letter 5014962 form of polynomials, where the burnup limit was established from the decay heat limit, enrichment and cooling time of an assembly. Due to the complications this created in the qualification process for fuel assemblies, and since both decay heat and burnup of any assembly are independently verified anyhow, this link was removed in a recent revision of the FSAR.

Instead, a fixed set of BECTs was established that is independent of the decay heat limit. The dose analyses were updated to account for this more generic approach. Details are presented in Section 5.4.11 of the FSAR. The BECTs that were established are listed in Tables 2.1.28 and 2.1.29.

Having these limits as independent means that meeting the BECT limits does not imply the decay heat limit are met, and vice versa. This could result a situation where an assembly meets the BECT but not the decay heat limit, or meet the decay heat but not the BECT limits. In both cases, the assembly would not be qualified for loading.

Note these BECTs are only applicable to the MPC-24/32/68/68M that were previously covered by the explicit link between decay heat limits and BECTs. They are not applicable to the MPC-68M patterns analyzed in Supplement 5.II or 5.III, and also not to the MPC-32M analyzed in Supplement 5.II. This is consistent with the applicability of the Topical Report.

It is noted that in some situations the BECTs are developed as polynomials, where the set of coefficients depend on the decay heat limit of the cell location in the basket. See for example Table 2.II.1.6. However, this just uses the decay heat limit as a convenient reference to certain cell location, and decay heat limits and BECT limits still have to be met independent of each other. Expressed differently, meeting the BECT limits does not in any way imply that the corresponding decay heat limit is met, and meeting the decay heat limit does not in any way imply that the BECT limits are met.

No changes to BECT limits.

This FSAR revision focuses solely on the introduction of the Topical report to allow increased flexibility in the thermal loading pattern. To keep this focus, no changes are introduced to the previously established BECTs. It is understood that this may lead to situations where an assembly may meet the decay heat limit, but not the BECT limits. In that case, the assembly would not be qualified for storage. Future revision of the FSAR may introduce changes to the BECT limits to avoid this, which then would require appropriate justification from a dose perspective No changes to Dose Analyses.

The dose analyses in Section 5.4.11 to support the BECT limits in Tables 2.1.28 and 2.1.29 are performed in a bounding fashion, i.e. using uniform loading of the baskets with any of the BECT combinations and determining the maximum dose rates. They therefore support the BECTs for any assembly in any location of the basket, and there are no restrictions on fuel placements implied or specified from these analyses. Any flexible placement permitted for fuel assemblies based on the Topical Report is therefore covered by these analyses, and no further dose analyses are needed.

This also includes any consideration for Non-Fuel Hardware (NFH). From a thermal perspective, HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 22C REPORT HI-2002444 1-8 Page 3 of 12

Attachment 3 to Holtec Letter 5014962 the decay heat value of any NFH present in the fuel assembly must be included before comparing the decay heat with the limit, regardless of the position in the basket. From a dose perspective, the contribution of the NFH, as previously established, is included in the analyses described in Section 5.4.11 in support of the BECTs. The introduction of the TR with its potentially more flexible assembly location is therefore fully covered by the dose analyses that include the NFH, and hence no further dose analyses are needed.

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 22C REPORT HI-2002444 1-9 Page 4 of 12

Attachment 3 to Holtec Letter 5014962 Figure 1.0.1: Thermal Topical Report Implementation Step 1 - Site develops candidate heat load pattern Step 2c - Use the topical report invariant thermal Step 2b - Use the model model to evaluate the developed for the with Step 2a - Ensure that sites candidate heat all applicable 72.48 the variations load pattern -

Step 2 - does the HI- No modifications to identified in Step 2 acceptance criteria are STORM 100 and system evaluate the sites are acceptable under as outlined in the topical and contents being used candidate heat load the existing CoC/FSAR report, and PCT must be at site match the TR pattern - acceptance under 72.48, if not higher than Step 2b. If invariant model criteria are process stops not, process stops temperatures and pressures lower than FSAR limit, and PCT Yes lower than Step 2c. If not, process stops Step 2dc - Compare the Step 3 - Evaluate the candidate heat load bounding temperatures of pattern under the topical report each component from 2b methodology and document in and 2c to those used in the qualification report, with all limitations FSAR structural analysis, (backfill, etc.) and update structural analysis if needed and permitted under 72.48. If Step Step4 4- -Site Sitechooses choosesfuel fueltotomeet meetthe the Step 5 - Site ensures loading not permitted under qualified qualifiedheatheatload loadpattern patternconfirming confirming procedures have the accurate 72.48, process stops that thatthe thefuel fuelalso alsomeets meetsother otherCoC CoC restrictions based on the topical restrictions, such as such restrictionsrequirements, FQT as BECT report methodology combinations HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 22C REPORT HI-2002444 1-38 Page 5 of 12

Attachment 3 to Holtec Letter 5014962 methodology described in Section 2.1.9.1.1 or 2.1.9.1.2 depending on whether uniform fuel loading or regionalized fuel loading is being implemented . The total permissible MPC heat load, for both uniform and regionalized loading, is determined in the following two subsections 2.1.9.1.1 and 2.1.9.1.2. Total MPC heat load and individual cell limits may also be determined using the methodology outlined in Topical Report HI-2200343-A. These fuel assemblies must still meet the fuel qualification requirements based on burnup, enrichment, and cooling time outlined in Paragraph 2.1.9.1.3. The decay heat limits are independent of burnup, cooling time, or enrichment and are based strictly on the thermal analysis described in Chapter 4 or the topical report [1.0.7] referenced above . Decay heat limits must be met for all contents in a fuel storage location (i.e., fuel and PWR non-fuel hardware, as applicable).

2.1.9.1.1 Uniform Fuel Loading Decay Heat Limits for ZR-Clad Fuel Table 2.1.26 provides the maximum allowable decay heat per fuel storage location for ZR-clad fuel in uniform fuel loading for each MPC model in aboveground storage . Even if the limits in Table 2.1.26 are met, the user must follow the instructions in the next section to calculate QCoC to determine if certain operational steps are required per the CoC. If the user needs to load fuel assemblies with a decay heat higher than the limits in Table 2.1.26, a regionalized loading pattern discussed in the next section may be considered.

2.1.9.1.2 Design Heat Load for ZR-Clad Fuel The discussion in this section provides the approach to determine the maximum permitted per cell heat load for long term-storage in a regionalized pattern. In addition, this section also provides the approach to determine the allowed per cell heat load for those operations that are dependent on the total MPC heat load. These include helium backfill pressure, supplemental cooling, drying method, and time requirements for clearing blockage on HI-STORM inlet vents.

The Design Basis heat load for the aboveground HI-STORM System, Qd, is 34 kW. Qd is based on the assumption that every storage cell in the MPC is generating an equal amount of heat. In other words, the specific heat generation rate, q, of each storage location is considered equal. Thus, in an MPC with n storage locations, Qd = n q Equation a In reality, however, the population of SNF and associated NFH loaded in the MPC invariably has unequal decay heat. If we consider the loaded decay heat in a cell as r, and ri denotes the loaded decay heat in location i, then the aggregate MPC heat load, Qt, is given by a simple summation, i.e.,

Note that the stainless steel-clad fuel decay heat limits apply to all fuel in the MPC, if a mixture of stainless steel and ZR-clad fuel is stored in the same MPC. The stainless steel-clad fuel assembly decay heat limits may be found in Table 2.1.17 through 2.1.24 Maximum allowable heat loads in 100U underground storage are defined in Supplement 2.I; however the discussion in Section 2.1.9.1 also applies to the 100U.

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Rev. 22 REPORT HI-2002444 2-45 Page 6 of 12

Attachment 3 to Holtec Letter 5014962 calculated for 4 and 5 years.

• ZR-clad fuel assemblies must have a minimum enrichment, as defined in the glossary, greater than or equal to the value used in determining the maximum allowable burnup per Section 2.1.9.1.3 to be authorized for storage in the MPC.

• When complying with the maximum fuel storage location decay heat limits, users must account for the decay heat from both the fuel assembly and any PWR non-fuel hardware, as applicable for the particular fuel storage location, to ensure the decay heat emitted by all contents in a storage location does not exceed the limit.

• There are two options for helium backfill range (shown in Table 1.2.2). The lower helium backfill range has different per cell heat load limits given in Table 2.1.31.

Section 12.2.10 provides a practical example of determining fuel storage location decay heat, burnup, and cooling time limits and verifying compliance for a set of example fuel assemblies.

2.1.9.1.5 Supplemental Cooling Threshold Heat Loads Fuel loading operations involving the handling of High Burnup Fuel (HBF) in a dewatered MPC emplaced in a HI-TRAC transfer cask require additional cooling under certain thermal loads to address reduced heat dissipation relative to the normal storage condition. To address this requirement the Supplemental Cooling System (SCS) defined in Appendix 2.C is mandated under threshold heat loads defined in Section 4.5 and Table 2.1.30. The specific design of a SCS must accord with site-specific needs and resources, including the availability of plant utilities. However, a set of specifications to ensure that the performance objectives of the SCS are satisfied by plant-specific designs are set forth in Appendix 2.C.

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Rev. 22 REPORT HI-2002444 2-49 Page 7 of 12

Attachment 3 to Holtec Letter 5014962 MPC Design PCT at Sea Level PCT at 1500 feet MPC-32 PWR 711.4oF 723.8oF MPC-68 BWR 697.1oF 718.2oF These results show that the PCT, including the effects of site elevation, continues to be well below the regulatory cladding temperature limit of 752oF. In light of the above evaluation, it is not necessary to place any ISFSI elevation constraints for HI-STORM deployment at elevations up to 1500 feet. If, however, an ISFSI is sited at an elevation greater than 1500 feet, the effect of altitude on the PCT shall be quantified as part of the 10 CFR 72.212 evaluation for the site using the site ambient conditions.

Heat load patterns can be developed in accordance with the thermal topic report (TR) [4.4.3]. If the screening criteria defined in the TR are met when performing the long-term storage evaluation, then no other storage conditions, including the effect of site elevation, need to be considered.

However, even if one of the screening criteria defined in the TR is not met, effects of site elevation must be evaluated for heat load patterns developed in accordance with the TR and compliance demonstrated with the acceptance criteria specified in the TR.

4.4.5 Maximum Internal Pressure 4.4.5.1 MPC Helium Backfill Pressure For design basis heat load, the helium backfill shall be sufficient to produce the required operating pressure of 7 atmospheres (absolute) during normal storage at reference conditions (See Table 4.0.1). Thermal analyses performed on the different MPC designs indicate that this operating pressure requires a certain helium backfill pressure specified at a reference temperature (70ºF).

The minimum backfill pressure to attain this operating pressure for each MPC type is provided in Table 4.4.11. An upper limit on the helium backfill pressure corresponds to the design pressure of the MPC vessel (Table 2.2.1). The upper limit on the backfill pressure is also reported in Table 4.4.11. To bound the minimum and maximum backfill pressures listed in Table 4.4.11 with margin, a helium backfill specification is set forth in Table 4.4.12. These values support the technical specification of the system for the design basis heat load of the MPC.

In addition the technical specifications allow for using a wider range on the backfill pressure if the heat load of the MPC is less than 28.74 kW. The minimum of this range corresponds to an operating pressure of 5 atm. The heat loads for this condition are provided in Table 2.1.31. If the MPC is loaded such that Table 2.1.31 is satisfied, the lower pressure range in the technical specifications may be used.

It is conservative to backfill the MPC to the higher pressure range regardless of MPC heat load.

Two methods are available for ensuring that the appropriate quantity of helium has been placed in an MPC:

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 22C REPORT HI-2002444 4-26 Page 8 of 12

Attachment 3 to Holtec Letter 5014962

[4.4.2] Pressure Loss Charactersistics for In-Cell Flow of Helium in PWR and BWR Storage Cells, Holtec Report HI-2043285, Holtec International, Marlton, NJ, 08053.

[4.4.3] Topical Report for Allowance of Heat Load Patterns in HI-STORM 100 and HI-STORM FW Systems, Holtec Report HI-2200343-A.

[4.5.1] HI-STORM THERMAL-HYDRAULIC ANALYSES SUPPORTING UP TO 36.9 KW HIGH HEAT LOAD AMENDMENT, Holtec Report HI-2043317, Latest Revision.

[4.5.2] HI-STORM FW FSAR, Holtec Report HI-2084239, Rev. 1, Section 3.4.4.1.11, Docket No. 72-1032.

[4.6.1] United States Code of Federal Regulations, Title 10, Part 71.

[4.6.2] Gregory, J.J. et. al., Thermal Measurements in a Series of Large Pool Fires, SAND85-1096, Sandia National Laboratories, (August 1987).

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 22C REPORT HI-2002444 4-97 Page 9 of 12

Attachment 3 to Holtec Letter 5014962 Multi-Purpose Canister (MPC)

B 3.1.1 BASES SURVEILLANCE SR 3.1.1.1, SR 3.1.1.2 , and SR 3.1.1.3 (continued)

REQUIREMENTS of Appendix A to the CoC and the storage cell heat loads are less than or equal to the limits in either Table 3-3 of Appendix A to the CoC (regionalized) or Table 3-4 of Appendix A to the CoC (uniform), then the lower helium backfill pressure range in Table 3-2 item (i) can be used.

The higher backfill pressure range in Table 3-2 item (ii) must be used if the cask heat load is greater than the value in Table 3-2 and the storage cell heat load is greater than the value in either Table 3-3 or Table 3-4. Note that the higher backfill pressure range in Table 3-2 item (ii) is just a subset of the wider range in item (i), and therefore can always be used as an option. The storage cell heat load limits specified in Table 3-3 and Table 3-4 for MPC-68/68F/68FF are also applicable to the MPC-68M, consistent with the analyses in the FSAR. Alternatively, the helium backfill pressure limit can be calculated for heat load patterns developed according to the Topical Report HI-2200343-A based on the methodology in described in the Topical Report. HI-2200343-A Meeting the helium leak rate limit ensures there is adequate helium in the MPC for long term storage and that there is no credible effluent dose from the cask.

All of these surveillances must be successfully performed once, prior to TRANSPORT OPERATIONS to ensure that the conditions are established for SFSC storage which preserve the analysis basis supporting the cask design.

REFERENCES 1. FSAR Sections 1.2, 4.4, 4.5, 7.2, 7.3 and 8.1

2. Interim Staff Guidance Document 11

3. Interim Staff Guidance Document 18

4. Deleted HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 22C REPORT HI-2002444 B 3.1.1-9 Page 10 of 12

Attachment 3 to Holtec Letter 5014962 SFSC Heat Removal System B 3.1.2 BASES ACTIONS (continued) B.1 If the heat removal system has been determined to be inoperable, it must be restored to operable status within the Completion Time per the Table in the CoC for OVERPACKS containing MPCs with heat loads in excess of the heat loads in Table B.1-1 (below) at the time of inspection. This is a reasonable period of time to take action to remove the obstructions in the air flow path.

Table B.1-1 (Threshold* heat loads for HI-STORM 100 System Surveillance Frequency and Completion Time to restore heat removal system to operable status)

MPC Model(s) Threshold Heat Load Threshold Heat Load (per canister) (per assembly) 24 (all variants) 18 kW 0.75 kW 68 (all variants) 18 kW 0..264 kW 32 (all variants) 16 kW 0.5 kW Alternatively, for OVERPACKS containing MPCs with heat loads up to the thresholds in Table B.1-1 at the time of inspection, the system must be restored to operable status within twenty-four hours. Twenty-four hours is a reasonable period of time for these lower heat load systems since the temperature limits of the system components and fuel cladding are not exceeded and the event is not time limiting.

Note that topical report HI-2200343-A provides an optional method for calculating completion time for all the actions in this LCO.

(continued)

HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 22C REPORT HI-2002444 B 3.1.2-4 Page 11 of 12

Attachment 3 to Holtec Letter 5014962 SFSC Heat Removal System B 3.1.2 BASES SURVEILLANCE SR 3.1.2 (continued)

REQUIREMENTS As an alternative, for OVERPACKs with air temperature monitoring instrumentation installed in the air outlets, the temperature rise between ambient and the OVERPACK air outlet may be monitored to verify operability of the heat removal system. Blocked air ducts will reduce air flow and increase the temperature rise experienced by the air as it removes heat from the MPC. Based on the analyses, provided the air temperature rise is less than the limit stated in the SR (or calculated using topical report HI-2200343-A),

adequate air flow and, therefore, adequate heat transfer is occurring to provide assurance of long term fuel cladding integrity. The reference ambient temperature used to perform this Surveillance shall be measured at the ISFSI facility.

The Frequency for aboveground systems per the Completion Time Table in the CoC and 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> for underground systems is reasonable based on the time necessary for SFSC components to heat up to unacceptable temperatures assuming design basis heat loads, and allowing for corrective actions to take place upon discovery of blockage of air ducts. For aboveground systems containing MPCs with heat loads less than or equal to the threshold heat loads in Table B.1-1 at the time of inspection, the surveillance frequency of 30 days is appropriate, since the system components and peak cladding temperature limits for 30-day accident are not exceeded and the event is not time limiting.

REFERENCES 1. FSAR Chapter 4

2. FSAR Sections 11.2.13 and 11.2.14

3. ANSI/ANS 57.9-1992 HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 22C REPORT HI-2002444 B 3.1.2-9 Page 12 of 12