ML19092A172
| ML19092A172 | |
| Person / Time | |
|---|---|
| Site: | Holtec |
| Issue date: | 03/20/2019 |
| From: | Holtec |
| To: | Division of Spent Fuel Management |
| Shared Package | |
| ML19092A192 | List: |
| References | |
| 5014867 | |
| Download: ML19092A172 (10) | |
Text
Attachment 1 to Holtec Letter 5014867 LAR 1014-15
SUMMARY
OF PROPOSED CHANGES Page 1 of 10 Proposed Change #1 A new version of a transfer cask called HI-TRAC MS has been added which includes an option for variable weight of the lead and water jacket and add cooling passages to the bottom lid. HI-TRAC MS is for use with all MPCs previously approved in the HI-STORM 100 system, the new MPC-32M, MPC-32 Version 1 and MPC-68 Version 1. Table 1 lists the MPCs proposed for use with the HI-TRAC MS.
Reason for Proposed Change #1 The HI-TRAC design has been updated to allow full cask loading of plants within crane lifting weight limits. Additional cooling passages have been added to allow for storage of canisters containing higher heat loads. The increased heat load storage capability supports decommissioning of plants in a timely manner.
Justification for Proposed Change #1 The HI-TRAC MS provides an option for variable thickness of the lead shielding based on site-specific requirements. The HI-TRAC MS provides the necessary shielding to maintain occupational dose ALARA during the fuel loading and transfer operation of the MPC in the HI-TRAC MS to the stackup location. This change aligns the HI-STORM 100 system with the HI-STORM FW system, which allows for variances in the HI-TRAC weight.
The areas of safety that require re-consideration, for HI-TRAC MS are structural loadings, thermal analyses, and dose evaluations. The full qualification of the HI-TRAC MS is included in the new Supplement II, to the FSAR (which also contains material for Changes #2, #3, and
- 4). Supplement II only identifies the areas that differ from the main body of the FSAR for the HI-TRAC MS, MPC-32M, MPC-32 and 68 Version 1, and HI-STORM 100 Version E. For the most recent complete version of the HI-STORM 100 FSAR submitted to the NRC, please see ML18130A039.
Proposed Change #2 Inclusion of MPC-32M.
MPC-32M is the PWR counterpart to the MPC-68M, previously certified in the HI-STORM 100 system. The MPC-32M fuel basket, like the MPC-68M, is made entirely from Metamic-HT. The MPC-32M enclosure vessel baseplate is slightly thickened to increase its pressure and load bearing capacity. The MPC-32M is evaluated for use with the HI-STORM 100S Version E overpack. The HI-STORM 100S Version E is introduced in the amendment.
MPC-32M is evaluated for use with all HI-TRAC transfer casks previously approved for use in the HI-STORM 100 system and the new HI-TRAC MS, introduced in this amendment.
to Holtec Letter 5014867 LAR 1014-15
SUMMARY
OF PROPOSED CHANGES Page 2 of 10 MPC-32M and its respective approved contents have also been added to the draft CoC Appendix D.
Reason for Proposed Change #2 This proposed change allows for storage of PWR fuel assemblies in the MPC-32M. This proposed change allows for storage of fuel assemblies with higher heat loads. This proposed change support the timely decommissioning of sites.
The thickened enclosure vessel baseplate allows increased helium backfill pressures for storage.
This increases the thermal ability of the canister, allowing for storage of higher heat loads. Last cycle fuel assemblies have higher heat loads. This change supports timely decommissioning of sites by allowing storage of last cycle fuel assemblies with reduced cooling times.
The MPC-32M basket is made of Metamic-HT. This increases the subcriticality function of the canister, allowing loading of more reactive fuel assemblies. The MPC-32M basket allows for storage of last cycle fuel assemblies to support timely decommissioning of sites.
Justification for Proposed Change #2 The MPC-32M basket utilizes the same Metamic-HT neutron absorber as the MPC-68M. The MPC-32M has been evaluated against the previously certified MPCs, and the HI-STORM 100 FSAR has been updated to identify if the existing analyses are bounding or if new analyses have been performed. The same or enhanced methodologies for evaluating previously approved canisters has been used in the MPC-32M evaluations.
The full qualification of the MPC-32M is included in the new Supplement II, to the FSAR (which also contains material for Changes #1, #3, and #4). Supplement II only identifies the areas that differ from the main body of the FSAR for the HI-TRAC MS, MPC-32M, MPC-32 and 68 Version 1, and HI-STORM 100 Version E. For the most recent complete version of the HI-STORM 100 FSAR submitted to the NRC, please see ML18130A039.
Proposed Change #3 Inclusion of MPC-32 Version 1 and MPC-68 Version 1.
Version 1 of MPC-32 and MPC-68 are slightly modified updates of their classical counterparts wherein the cell openings are slightly enlarged to improve the ability to store Damaged Fuel Containers and the enclosure vessel baseplate is slightly thickened to increase its pressure and load bearing capacity. The basket material, as before, is made of Alloy X.
Version 1 baskets are evaluated for use with HI-STORM 100 classic and the new HI-STORM 100S Version E introduced in this amendment and all HI-TRAC transfer casks previously to Holtec Letter 5014867 LAR 1014-15
SUMMARY
OF PROPOSED CHANGES Page 3 of 10 approved for use in the HI-STORM 100 system and the HI-TRAC MS introduced in this amendment.
These versions of the previously approved canisters have also been added to the draft CoC. The allowable contents for the version 1 canisters remain the same as for the previously approved MPC-32 and MPC-68.
Reason for Proposed Change #3 The slightly larger cell opening increases the operational ability to load Damaged Fuel Containers in the Version 1 of MPC-32 and MPC-68. The thicker enclosure vessel baseplate allows an increased helium backfill pressure. These changes support the timely decommissioning of sites by allowing easier storage of damaged fuel assemblies.
Justification for Proposed Change #3 Version 1 of MPC-32 and MPC-68 have been evaluated against the previously certified MPCs, and the HI-STORM 100 FSAR has been updated to identify if the existing analyses are bounding or if new analyses have been performed. The same methodology used for previously approved canisters is used for the analyses for the version 1 canisters.
The full qualification of the MPC-32 Version 1 and MPC-68 Version 1 is included in the new Supplement II, to the FSAR (which also contains material for Changes #1, #2, and #4).
Supplement II only identifies the areas that differ from the main body of the FSAR for the HI-TRAC MS, MPC-32M, MPC-32 and 68 Version 1, and HI-STORM 100 Version E. For the most recent complete version of the HI-STORM 100 FSAR submitted to the NRC, please see ML18130A039.
Proposed Change #4 Add HI-STORM 100S Version E. Table 1 lists the MPCs proposed for storage in the Version E overpack.
HI-STORM 100S Version E is a variant of HI-STORM 100S Version B with the following improvements: increased number of inlet vents, elevated inlet vents, added bottom supports to elevate the MPC inside the enclosure vessel, improved top lid design to limit shear load on the closure bolts and provide increased outlet flow area.
The HI-STORM 100S Version E overpack is analyzed for use with all MPCs previously approved in the HI STORM 100 system, the new MPC-32M, MPC-32 Version 1 and MPC-68 Version 1. The MPC-32M, MPC-32 Version 1 and MPC-68 Version 1 are also introduced in this amendment.
to Holtec Letter 5014867 LAR 1014-15
SUMMARY
OF PROPOSED CHANGES Page 4 of 10 Reason for Proposed Change #4 The HI-STORM 100S Version E allows for storage of higher heat loads. This supports the needs of operating sites and site undergoing decommissioning.
The HI-STORM 100S Version E inlet air vents provide increased cooling, allows continued heat rejection during a flood event, and improve fabricability. These enhancements are a result of the additional number of inlet air vents, the angled design of the inlet air vents and the higher axial location of the inlet air vents.
The addition of the bottom supports inside of the overpack serve to elevate the MPC inside of the overpack, which allows flow underneath the MPC. This provides additional cooling to the MPC and also places the MPC in an area of increased shielding.
The improved top lid is designed with an increased outlet flow area. This improves the thermal efficiency of the system. The top lid closure bolts are also designed to reduce the shear load during tip-over.
Justification for Proposed Change #4 The full qualification of the HI-STORM 100S Version E is included in the new Supplement II, to the FSAR (which also contains material for Changes #1, #2, and #3). Supplement II only identifies the areas that differ from the main body of the FSAR for the HI-TRAC MS, MPC-32M, MPC-32 and 68 Version 1, and HI-STORM 100 Version E. For the most recent complete version of the HI-STORM 100 FSAR submitted to the NRC, please see ML18130A039.
Section 2.2 of the HI-STORM 100 FSAR provides a complete list of the loadings germane to the safety analysis of the storage system. The determination of non-governing loadings (such as lightning, high wind, and snow) is based on the design characteristics of the system (such as a large metal mass, heavy weight, and a thick structural Top Lid) and has been made in the FSAR.
The proposed changes to Version E do not affect these characteristics. The peak fuel cladding temperature is guaranteed to be lower than that in its predecessor because the air inlet and outlet passages are larger in the Version E.
The above consideration of applicable governing loads and conditions leads to the conclusion that the Version E meets all safety metrics per the system FSAR Proposed Change #5 Addition of three additional BWR fuel types, 10x10I, 10x10J, and 11x11A, to the approved contents in CoC 1014, Appendix B for MPC-68M only.
to Holtec Letter 5014867 LAR 1014-15
SUMMARY
OF PROPOSED CHANGES Page 5 of 10 Reason for Proposed Change #5 This proposed change allows storage of additional fuel types in the MPC-68M only for the HI-STORM 100 System. These fuel types are currently in use by operating reactors requiring storage.
Justification for Proposed Change #5 The areas of safety that require re-consideration, for the additional fuel types are criticality, structural, thermal and shielding. Two of these fuel types, 10x10I and 11x11A, were previously submitted for approval with the HI-STORM FW LAR-5.
Criticality analyses of the new fuel were performed. The criticality analyses are summarized in Supplement 6.II of the FSAR and are demonstrated to be acceptable.
The new fuel types were determined to be bounded by the design basis fuel already analyzed in the FSAR for thermal and structural. For shielding, the design basis assembly in the FSAR is still considered representative; therefore, no additional analyses were required. Structural, thermal and shielding requirements are summarized in Supplements 3.II, 4.II and 5.II and are demonstrated to be acceptable.
Proposed Change #6 Lower ambient temperature to 70 degrees F for HI-STORM 100S Version E.
Reason for Proposed Change #6 Reduces the allowed ambient temperature under long-term storage.
Justification for Proposed Change #6 Normal ambient temperature used in the analyses is the bounding annual average temperature.
The current value is 80 degrees F. Reducing the bounding average temperature to 70 degrees F provides additional margin to approved analyses. This temperature limit bounds most clients and the 80 degree limit is too conservative.
Proposed Change #7 Add HI-DRIP and Dry Ice Jacket ancillary system.
to Holtec Letter 5014867 LAR 1014-15
SUMMARY
OF PROPOSED CHANGES Page 6 of 10 HI-DRIP is an optional ancillary system designed to prevent water within the MPC from boiling during loading/unloading operations while the loaded MPC is in the HI-TRAC transfer cask.
FSAR section 1.2.1.6 describes the HI-DRIP system.
Reason for Proposed Change #7 The HI-DRIP system has potential use during the period when the loaded MPC is full of water and is out of the pool. The HI-DRIP is used to provide additional cooling for the MPC in the HI TRAC during the interval after it has been lifted out of the fuel pool and is subject to surface decontamination, lid welding and related operations which precede the evacuation of water from the MPC followed by activation of the Forced Gas Dehydrator (FGD). This time period is termed fuel packaging. As such, HI-DRIP is essentially a device to provide additional cooling of the MPC's water during the period it is full of water and out of the pool.
Justification for Proposed Change #7 The area of safety that requires consideration, for the HI-DRIP system is thermal.
Thermal analysis of the use of the HI-DRIP system is summarized in Sections 4.II.5.3. The optional use of the HI-DRIP system is shown to be acceptable.
Proposed Change #8 Allow for partial gadolinium credit for BWR fuel assemblies types 10x10 and 11x11 assembly classes in the MPC-68M.
Reason for Proposed Change #8 The use of partial gadolinium credit allows storage of BWR fuel with a greater maximum fuel enrichment limit.
Justification for Proposed Change #8 The restrictions for gadolinium credit are outlined in the proposed HI-STORM 100 FSAR Chapter 2, as well as the draft Appendix B to the CoC. These restrictions have been evaluated for their impact on criticality, as described in Chapter 6.
Proposed Change #9 Remove dose rate from Accident Analysis for Non-Mechanistic Tip-over as referenced in FSAR Subsection 11.2.3.
to Holtec Letter 5014867 LAR 1014-15
SUMMARY
OF PROPOSED CHANGES Page 7 of 10 Reason for Proposed Change #9 The non-mechanistic tip-over is a non-credible event. The dose rate required by 10CFR72.106 at the controlled area boundary is overly conservative for an event which is recognized as not credible.
Justification for Proposed Change #9 The Tip-Over event is determined to be non-credible. Imposing the dose limit restriction is overly conservative for the design for an event which has been determined to be non-credible.
Proposed Change #10 Include allowance for canisters currently loaded under earlier amendments which had different helium leak test requirements. These canisters were manufactured and loaded in full compliance with the certificate effective at the time; however, subsequent amendments required additional testing. For this change, modifications are made in CoC Condition 2, CoC Appendix A, and FSAR Chapters 2 and 9.
Reason for Proposed Change #10 The licensing basis for canisters loaded under CoC Amendments 2 through 7 did not include a requirement to helium leak test the base metal used for the MPC lids. Therefore, although these canisters are currently safely stored at various sites in full compliance with their applicable certificate of compliance amendment, sites cannot upgrade them to the latest amendment of the system as otherwise supported by the CoC.
This change will allow those sites to perform the necessary evaluations and upgrade the canisters to the most up to date amendment. This change only applies to previously loaded and stored canisters; current and future canisters will continue to be helium leak tested as specified. The ability for sites to upgrade to the latest amendment provides an operational benefit to sites (particularly shut-down sites) to minimize the administrative burden of maintaining multiple licensing bases for multiple amendments. This reduced administrative burden will then allow an increased focus on safety.
Justification for Proposed Change #10 A number of canisters were loaded under earlier amendments without the requirement to test the base metal. For these canisters, Holtec previously analyzed the detectible leak rate, and the loss of helium in the canister which could result from a leak of this magnitude, and the effects on the canisters ability to reject heat under such a condition. This was documented in letters from the affected sites to the NRC in 2010. The results of these letters showed that for the loaded heat to Holtec Letter 5014867 LAR 1014-15
SUMMARY
OF PROPOSED CHANGES Page 8 of 10 loads, the canisters will maintain the peak cladding temperature of the fuel below the regulatory limit. Monitoring of the radiation levels at the ISFSIs demonstrates that there is no significant radioactive release from these canisters that would indicate that there is a leak in the lids.
Based on this information, NRC had previously concluded that continued use of the MPC canisters under HI-STORM 100 CoC Amendments 2 through 7 is acceptable. The proposed change allows sites to perform the necessary evaluations for those systems to be upgraded to a later amendment. This change does not require any physical change to the system and therefore the continued use of those systems maintains the same safety margins. No change is requested for new systems to be stored under Amendment 15, this change only applies to currently loaded and safely stored systems.
Holtec previously submitted this change under Amendment 13, but due to schedule needs postponed the change. However, the NRC had issued RSIs on the subject, therefore to avoid repeat questions, this submittal contains the Holtec response to the RSI from LAR 13 regarding this proposed change and incorporates, where appropriate, comments previously made during the LAR 13 review.
Proposed Change #11 Update drawing 7195 for the MPC-68M to remove dimensions on the drawing that are not used in the safety analysis.
Reason for Proposed Change #11 Remove information from the drawing that is not used in the calculations to support the safety analysis. The extraneous information on the drawing is too restrictive and contains information that is not needed to support the safety analysis.
Justification for Proposed Change #11 The information being removed from the drawing is not used in calculations to support the safety analysis. No design changes are being made to the system. The revised drawing will continue to support the safety analysis used to determine compliance with all analyzed safety limits. The revised drawing has been evaluated for its impact on structural, thermal, criticality, and shielding as described in FSAR Chapters 3, 4, 5 and 6.
Proposed Change #12 Include Dry Ice Jacket (DIJ) as optional alternate cooling method for short term operation of the loaded HI-TRAC. The description of the Dry Ice Jacket is contained in FSAR section 1.2.1.7 to Holtec Letter 5014867 LAR 1014-15
SUMMARY
OF PROPOSED CHANGES Page 9 of 10 Reason for Proposed Change #12 At times, the loaded HI-TRAC must travel in the horizontal orientation due to plant configuration. Site specific analysis is performed to allow short term operation of the HI-TRAC in the horizontal orientation. The Dry Ice Jacket, DIJ, is provided as an option to facilitate the short-term operation of the HI-TRAC in the horizontal orientation.
Justification for Proposed Change #12 The area of safety that requires consideration, for the Dry Ice Jacket, DIJ, is thermal.
Thermal analysis of the use of the DIJ is summarized in Supplement 4.II.6.2. The optional use of the DIJ system is shown to be acceptable for short term operation of the loaded HI-TRAC.
Clarifications and Editorial Suggestions in the CoC/FSAR A) Correct Figure number for DFI in Section 1.2.3.
B) Clarify CoC Appendix B section 3.4.11 and 3.9 to Holtec Letter 5014867 LAR 1014-15
SUMMARY
OF PROPOSED CHANGES Page 10 of 10 Table 1 Overpack, Transfer Cask and MPC Matrix Overpack/ Transfer Cask MPC HI-STORM Version E (Overpack)
MPC-24, 24E, 24EF, 32, 32F, 68, 68F, 68FF and 68M. (Approved for use in the HI-STORM 100 system)
MPC-32M, MPC-32 Version 1, MPC-68 Version 1 (Proposed for use per LAR 15)
HI-STORM 100 classic and Version B (Overpack)
MPC-24, 24E, 24EF, 32, 32F, 68, 68F, 68FF and 68M. (Approved for use in the HI-STORM 100 system)
MPC-32 Version 1, MPC-68 Version 1 (Proposed for use per LAR 15)
HI-TRAC MS (Transfer cask)
MPC-24, 24E, 24EF, 32, 32F, 68, 68F, 68FF and 68M. (Approved for use in the HI-STORM 100 system)
MPC-32M, MPC-32 Version 1, MPC-68 Version 1 (Proposed for use per LAR 15)
HI-TRAC 125, 125D, 100, 100D, 100D (Transfer cask)
MPC-24, 24E, 24EF, 32, 32F, 68, 68F, 68FF and 68M. (Approved for use in the HI-STORM 100 system)
MPC-32M, MPC-32 Version 1, MPC-68 Version 1 (Proposed for use per LAR 15)