ML23013A346
| ML23013A346 | |
| Person / Time | |
|---|---|
| Site: | Holtec |
| Issue date: | 01/13/2023 |
| From: | Holtec |
| To: | Office of Nuclear Material Safety and Safeguards |
| Shared Package | |
| ML23013A337 | List: |
| References | |
| 5014956, EPID L-2021-LLA-0039 | |
| Download: ML23013A346 (1) | |
Text
Holtec Letter 5014956 Attachment 8 moisture is being removed. The warm, dry gas is supplied to the MPC drain port and circulated through the MPC cavity where it absorbs moisture. The humidified gas travels out of the MPC and through appropriate equipment to cool and remove the absorbed water from the gas. The dry gas may be heated prior to its return to the MPC in a closed loop system to accelerate the rate of moisture removal in the MPC. This process is continued until the temperature of the gas exiting the demoisturizing module described in Appendix 2.B meets the specified limit.
Following moisture removal, the MPC is backfilled with a predetermined amount of helium gas. The helium backfill ensures adequate heat transfer during storage and provides an inert atmosphere for long-term fuel integrity. Cover plates are installed and seal-welded over the MPC vent and drain ports with liquid penetrant examinations performed on the root and final passes. The cover plates are helium leakage tested to confirm that they meet the established leakage rate criteria. If the redundant port cover design is used, the helium leakage test is not required to be performed.
The MPC closure ring is then placed on the MPC, aligned, tacked in place, and seal welded, providing redundant closure of the MPC lid and cover plates confinement closure welds. Tack welds are visually examined, and the root and final welds are inspected using the liquid penetrant examination technique to ensure weld integrity. The annulus shield is removed and the remaining water in the annulus is drained. The AWS Baseplate shield is removed. The MPC lid and accessible areas of the top of the MPC shell are smeared for removable contamination and HI-TRAC dose rates are measured. The HI-TRAC top lid is installed and the bolts are torqued. The MPC lift cleats are installed on the MPC lid. The MPC lift cleats are the primary lifting point of the MPC.
Rigging is installed between the MPC lift cleats and the lift yoke. . The rigging supports the MPC within HI-TRAC while the pool lid is replaced with the transfer lid. For the standard design transfer cask, the HI-TRAC is manipulated to replace the pool lid with the transfer lid. The MPC lift cleats and rigging support the MPC during the transfer operations.
MPC transfer from the HI-TRAC transfer cask into the overpack may be performed inside or outside the fuel building. Similarly, HI-TRAC and HI-STORM may be transferred to the ISFSI in several different ways. The loaded HI-TRAC may be handled in the vertical or horizontal orientation. The loaded HI-STORM can only be handled vertically.
For MPC transfers inside the fuel building, the empty HI-STORM overpack is inspected and staged with the lid removed, the alignment device positioned, and, for the HI-STORM 100 overpack, the vent duct shield inserts installed. If using HI-TRAC 100D, 125D, or 100G, the HI-STORM mating device is placed (bolted if required by generic or site specific seismic evaluation) to the top of the empty overpack (Figure 1.2.18). The loaded HI-TRAC is placed using the fuel building crane on top of HI-STORM, or the mating device, as applicable. After the HI-TRAC is positioned atop the HI-STORM or positioned (bolted if required by generic or site specific seismic evaluation) atop the mating device, as applicable, the MPC is raised slightly. With the standard HI-TRAC design, the transfer lid door locking pins are removed and the doors are opened. With the HI-TRAC 100D, 125D, and 100G, the pool lid is removed using the mating device. The MPC is lowered into HI-STORM. Following verification that the MPC is fully lowered, slings are disconnected and lowered onto the MPC lid. For the HI-STORM 100, the doors are closed and the HI-TRAC is prepared for removal from on top of HI-STORM (with HI-TRAC 100D, 125D, and 100G, the transfer cask must HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 21E REPORT HI-2002444 1-69 1 of 10
Holtec Letter 5014956 Attachment 8 Table 2.0.1 (continued)
MPC DESIGN CRITERIA
SUMMARY
Type Criteria Basis FSAR Reference Leak Testing:
Welds Tested MPC shell to shell and MPC ISG-25 Section 9.1 shell to baseplate welds (Fabrication). ISG-18 Port covers-to-MPC lid (field)
(not required when the redundant port cover design is used)
Base Metals Tested MPC shell, MPC baseplate, ISG-25 Section 9.1 MPC lid (Fabrication).
MPC vent and drain port cover plates (Field).
Medium Helium ANSI N14.5 Section 9.1 Max. Leak Rate Leaktight ANSI N14.5 Section 9.1 Monitoring System None 10CFR72.128(a)(1) Section 2.3.2.1 Pressure Testing (if specified ):
Minimum Test Pressure 125 psig (hydrostatic) - Governing requirements are 120 psig (pneumatic) specified in Sections 8.1 and 9.1 Welds Tested MPC Lid-to-Shell, MPC Shell - Sections 8.1 and 9.1-seams, MPC Shell-to-Baseplate Medium Water or helium - Section 8.1 and Chapter 9-Retrievability:
Normal and Off-normal: No Encroachment on Fuel 10CFR72.122(f) & (l) Sections 3.4 and 3.1.2 Post (design basis) Accident Assemblies Criticality: 10CFR72.124 &
Method of Control Fixed Borated - Section 2.3.4 Neutron Absorber, Geometry, and Soluble Boron HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 21E19 REPORT HI-2002444 2-19 2 of 10
Holtec Letter 5014956 Attachment 8 Table 2.2.15 (continued)
LIST OF ASME CODE ALTERNATIVES FOR HI-STORM 100 SYSTEM Reference ASME Alternative, Justification &
Component Code Code Requirement Compensatory Measures Section/Article MPC Lid and Closure Ring NB-4243 Full penetration welds MPC lid and closure ring are not full penetration welds.
Welds required for Category C They are welded independently to provide a redundant Joints (flat head to main seal. Additionally, a weld efficiency factor of 0.45 has shell per NB-3352.3) been applied to the analyses of these welds.
MPC Closure Ring, Vent and NB-5230 Radiographic (RT) or Root (if more than one weld pass is required) and final liquid Drain Cover Plate Welds ultrasonic (UT) penetrant examination to be performed in accordance with examination required. NB-5245. The closure ring provides independent redundant closure for vent and drain cover plates. Vent and drain port cover plate welds are helium leakage tested. If the redundant port cover design is used, a helium leakage test is not required.
MPC Lid to Shell Weld NB-5230 Radiographic (RT) or Only UT or multi-layer liquid penetrant (PT) examination is ultrasonic (UT) permitted. If PT examination alone is used, at a minimum, it examination required. will include the root and final weld layers and each approx.
3/8" of weld depth.
MPC Enclosure Vessel and Lid NB-6111 All completed pressure The MPC vessel is seal welded in the field following fuel retaining systems shall be assembly loading. The MPC vessel shall then be pressure pressure tested. tested as defined in Chapter 9. Accessibility for leakage inspections precludes a Code compliant pressure test. Since the shell welds of the MPC cannot be checked for leakage during this pressure test, the shop leakage test to 10-7 ref cc/sec (as described in Chapter 9) provides reasonable assurance as to its leak tightness. All MPC vessel welds (except closure ring and vent/drain cover plate) are inspected by volumetric examination, except the MPC lid-to-shell weld shall be verified by volumetric or multi-layer PT examination. If PT alone is used, at a minimum, it must include the root and final layers and each approximately 3/8 inch of weld depth. For either UT or PT, the maximum undetectable flaw size must be demonstrated to be less than HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 21E19 REPORT HI-2002444 2-204 3 of 10
Holtec Letter 5014956 Attachment 8 Table 2.II.2.6 List of ASME Code Alternatives for HI-STORM Multi-Purpose Canisters (MPCs)
MPC Closure NB-5230 Radiographic (RT) or Root (if more than one weld pass is required)
Ring, Vent and ultrasonic (UT) examination and final liquid penetrant examination to be Drain Cover required. performed in accordance with NB-5245. The Plate Welds closure ring provides independent redundant closure for vent and drain cover plates. Vent and drain port cover plate welds are helium leakage tested. As an alternative, the helium leakage test does not have to be performed if the redundant port cover design is used.
MPC Lid to NB-5230 Radiographic (RT) or
- Only progressive liquid penetrant (PT)
Shell Weld ultrasonic (UT) examination examination is permitted. PT required. examination will include the root and final weld layers and each approx. 3/8" of weld depth.
HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 21E REPORT HI-2002444 2.II-48 4 of 10
Holtec Letter 5014956 Attachment 8
- c. Verify that the vent and drain port connections are closed such that the leakage past the port closure will not affect the port cover plate weldsDeleted.
Note:
ASME Boiler and Pressure Vessel Code [8.1.3],Section V, Article 6 provides the liquid penetrant inspection methods. The acceptance standards for liquid penetrant examination shall be in accordance with ASME Boiler and Pressure Vessel Code,Section III, Subsection NB, Article NB-5350 as specified on the Design Drawings. ASME Code,Section III, Subsection NB, Article NB-4450 provides acceptable requirements for weld repair. NDE personnel shall be qualified per the requirements of Section V of the Code or site-specific program.
- d. Weld cover plate and perform NDE on the cover plate with approved procedures (See 9.1 and Table 2.2.15)
- e. Repair anyd weld defects in accordance with the sites approved code weld repair procedures.
If using redundant port cover plates, install the redundant port cover plate, perform the multi-pass welds, and perform NDE on the redundant port cover plates with approved procedures (See 9.1 and Table 2.2.15). Repair any weld defects in accordance with the sites approved code weld repair procedures.
- f. If not using redundant port cover plates, pPPerform a helium leakage rate test on the cover plate welds. (See 9.1 and Table 2.2.15). Acceptance Criteria are defined in Technical Specification LCO 3.1.1.
- g. Repair any weld defects in accordance with the sites approved code weld repair procedures.
- h. Deleted.
- i. Repeat for the drain port cover plate.
- 9. Perform a leakage test of the MPC vent and drain port cover plates as follows:
Note:
If the redundant port cover option is being implemented, Steps (a) through (g) are not performed.only the inner cover plate is tested.
Note:
The leakage detector may detect residual helium in the atmosphere from the helium injection process. If the leakage tests detect a leak, the area should be blown clear with compressed air or nitrogen and the location should be retested.
Note:
The following process provides a high concentration of helium gas in the cavity. Other methods that ensure a high concentration of helium gas are also acceptable.
- a. If necessary, remove the cover plate set screws or plugs.
- b. Flush the cavity with helium to remove the air and immediately install the set screws or plugs recessed below flush with the top of the cover plate.
HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 21E REPORT HI-2002444 8-29 5 of 10
Holtec Letter 5014956 Attachment 8
- c. Plug weld the recess above each set screw or plug to complete the penetration closure welding.
Note:
ASME Boiler and Pressure Vessel Code [8.1.3],Section V, Article 6 provides the liquid penetrant inspection methods. The acceptance standards for liquid penetrant examination shall be in accordance with ASME Boiler and Pressure Vessel Code,Section III, Subsection NB, Article NB-5350 as specified on the Design Drawings. ASME Code,Section III, Subsection NB, Article NB-4450 provides acceptable requirements for weld repair. NDE personnel shall be qualified per the requirements of Section V of the Code or site-specific program.
- d. Perform a liquid penetrant examination on the plug weld.
- e. Flush the area around the vent and drain cover plates with compressed air or nitrogen to remove any residual helium gas.
- f. Perform a helium leakage rate test of vent and drain cover plate welds in accordance with the Mass Spectrometer Leak Detector (MSLD) manufacturers instructions and ANSI N14.5 [8.1.2]. The MPC Helium Leak Rate acceptance criteria is provided in the Technical Specification LCO 3.1.1.
- g. Repair any weld defects in accordance with the site's approved code weld repair procedures. Re-perform the leakage test as required.
- h. If using redundant port cover plates, install the redundant port cover plate, perform the multi-pass welds, and perform NDE on the redundant port cover plates with approved procedures (See 9.1 and Table 2.2.15). Repair any weld defects in accordance with the sites approved code weld repair procedures.
- 10. Weld the MPC closure ring as follows:
ALARA Note:
The closure ring is installed by hand. No tools are required. Localized grinding to achieve the desired fit and weld prep are allowed.
- a. Install and align the closure ring. See Figure 8.1.8.
- b. Weld the closure ring to the MPC shell and the MPC lid, and perform NDE with approved procedures (See 9.1 and Table 2.2.15).
- c. Deleted.
- d. Deleted.
- e. Deleted.
- f. Deleted.
- g. Deleted.
- h. Deleted.
- i. Deleted.
- j. If necessary, remove the AWS. See Figure 8.1.7 for rigging.
HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 21E REPORT HI-2002444 8-30 6 of 10
Holtec Letter 5014956 Attachment 8 An option available on all MPCs is the addition of a second cover plate on the drain and vent ports. The outer cover plate is installed in a counterbored recess directly over the inner port cover. The outer port cover is welded using a minimum of three weld passes that bridge the weld joint. Visual and liquid penetrant examinations shall be performed on the root, final and at least one intermediate weld pass. Helium leak testing is not required when the redundant port cover design is used Leakage testing of the field welded MPC lid-to-shell weld and closure ring welds are not required.
Leak testing results for the MPC shall be documented and shall become part of the quality record documentation package.
Leakage testing of the vent and drain port cover plates, when required, shall be performed after welding of the cover plates and subsequent NDE. For instances where redundant port covers have been installed, leakage testing is only required on the inner port cover. The description and procedures for these field leakage tests are provided in FSAR Section 8.1 and the acceptance criteria are defined in the Technical Specifications in Appendix A to CoC 72-1014.
9.1.4 Component Tests 9.1.4.1 Valves, Rupture Discs, and Fluid Transport Devices There are no fluid transport devices or rupture discs associated with the HI-STORM 100 System.
The only valve-like components in the HI-STORM 100 System are the specially designed caps installed in the MPC lid for the drain and vent ports. These caps are recessed inside the MPC lid and covered by the fully-welded vent and drain port cover plates. No credit is taken for the caps' ability to confine helium or radioactivity. After completion of drying and backfill operations, the drain and vent port cover plates are welded in place on the MPC lid and are liquid penetrant examined and, when required, leakage tested to verify the MPC confinement boundary.
There are two pressure relief valves installed in the upper ledge surface of the HI-TRAC transfer cask water jacket. These pressure relief valves are provided for venting of the neutron shield jacket fluid under hypothetical fire accident conditions in which the design pressure of the water jacket may be exceeded. The pressure relief valves shall relieve at 60 psig and 65 psig. The HI-TRAC 100G pressure relief valves shall relieve at 50 psig and 60 psig.
9.1.4.2 Seals and Gaskets There are no confinement seals or gaskets included in the HI-STORM 100 System.
9.1.5 Shielding Integrity HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev.21E REPORT HI-2002444 9-10 7 of 10
Holtec Letter 5014956 Attachment 8 Table 9.1.1 (continued)
MPC INSPECTION AND TEST ACCEPTANCE CRITERIA Function Fabrication Pre-operation Maintenance and Operations Structural a) Assembly and welding of MPC components a) None. a) An ultrasonic (UT) examination or shall be performed per ASME Code Section multi-layer liquid penetrant (PT)
IX and III, Subsections NB and NG, as examination of the MPC lid-to-shell applicable. weld shall be performed per ASME Section V, Article 5 (or ASME b) Materials analysis (steel, neutron absorber, Section V, Article 2). Acceptance etc.), shall be performed and records shall be criteria for the examination are kept in a manner commensurate with defined in Subsection 9.1.1.1 and in "important to safety" classifications. the Design Drawings.
b) ASME Code NB-6000 pressure test shall be performed after MPC closure welding. Acceptance criteria are defined in the Code.
Leak Tests a) Helium leakage testing of the MPC shell and a) None. a) Helium leak rate testing shall be MPC shell to baseplate welds is performed on performed on the vent and drain the unloaded MPC. port cover plate to MPC lid field welds and the cover plate base b) Helium leakage testing of the MPC base metals. If the redundant port cover metals design is used on the vent and drain (shell, baseplate, lid) is performed. ports, Hhelium leak testing is notonly required on the inner port cover. See Technical Specification Bases in Chapter 12 for guidance on acceptance criteria.
HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 21E REPORT HI-2002444 9-18 8 of 10
Holtec Letter 5014956 Attachment 8 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 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.
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.
MPCs that utilize the redundant port cover design exhibit increased confinement boundary reliability. Each port cover plate is subjected to NDE to ensure the absence of porosity in the material and is welded to the MPC lid in the same manner as in the non-redundant design. Each cover plate weld is subjected to similar NDE acceptance criteria, where successful NDE will verify the associated welds integrity to maintain the MPC confinement boundary. As such, this surveillance does not need to be performed for MPCs that utilize the redundant port cover design.
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. 21E REPORT HI-2002444 B 3.1.1-9 9 of 10
Holtec Letter 5014956 Attachment 8 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 REQUIREMENTS The long-term integrity of the stored fuel is dependent on storage in a dry, inert environment. Cavity dryness may be demonstrated either by evacuating the cavity to a very low absolute pressure and verifying that the pressure is held over a specified period of time or by recirculating dry helium through the MPC cavity to absorb moisture until the gas temperature or dew point at the specified location reaches and remains below the acceptance limit for the specified time period. A low vacuum pressure or a demoisturizer exit temperature meeting the acceptance limit is an indication that the cavity is dry.
Table 3-1 of Appendices A and C to the CoC provide the appropriate requirements for drying the MPC cavity based on the applicable short-term temperature limit. The temperature limits are consistent with the guidance in NRC Interim Staff Guidance (ISG) Document 11.
Having the proper quantity of helium in the MPC ensures adequate heat transfer from the fuel to the fuel basket and surrounding structure of the MPC and precludes any overpressure event from challenging the normal, off-normal, or accident design pressure of the MPC.
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.
MPCs that utilize the redundant port cover design exhibit increased confinement boundary reliability. Each port cover plate is subjected to NDE to ensure the absence of porosity in the material and is welded to the MPC lid in the same manner as in the non-redundant design. Each cover plate weld is subjected to similar NDE acceptance criteria, where successful NDE will verify the associated welds integrity to maintain the MPC confinement boundary. As such, this surveillance does not need to be performed for MPCs that utilize the redundant port cover design.
(continued)
HOLTEC INTERNATIONAL COPYRIGHTED MATERIAL HI-STORM 100 FSAR Proposed Rev. 21E REPORT HI-2002444 IV.B 3.1.1-8 10 of 10