ML19098A179
| ML19098A179 | |
| Person / Time | |
|---|---|
| Site: | 07109375 |
| Issue date: | 03/19/2019 |
| From: | Pierre Saverot Spent Fuel Licensing Branch |
| To: | Christopher Regan Spent Fuel Licensing Branch |
| Saverot P | |
| Shared Package | |
| ML19098A177 | List: |
| References | |
| EPID: L-2019-LRM-0006 | |
| Download: ML19098A179 (20) | |
Text
a generation ahead by design HI-STAR ATB 1T TYPE B(U) TRANSPORTATION PACKAGE Revised Design to Meet 10 CFR 71 Acceptance Criteria Pre-Submittal Presentation to NRC (Non-Proprietary Version)
March 19, 2019 Holtec International Holtec copyrighted material
a generation ahead by design Presentation Agenda 2
- Meeting Objective
- Reasons for Change in Package Design
- Package Overview
- Specific Design Enhancements (Proprietary)
- Safety Evaluations Thermal Evaluation Containment Evaluation Shielding Evaluation Criticality Evaluation Structural Evaluation
- Structural Analysis Model & Results (Proprietary)
- Licensing Path Forward
- Open Discussion Holtec copyrighted material
a generation ahead by design Meeting Objective
- Provide an overview of the proposed HI-STAR ATB 1T application and package (contents, performance, and packaging design), highlighting major changes to cask/overpack design and safety evaluations
- Provide additional details on the structural design and qualification of the revised HI-STAR ATB 1T package, including the performance of the containment boundary seals under accident conditions 3
Holtec copyrighted material
a generation ahead by design 4
Reasons for Change in Package Design
- Earlier design was based upon strain-based acceptance criteria per ASME Appendices EE & FF for qualification of containment boundary First of a kind approach for 10 CFR 71 application Requires the use of SA-240 304/304L material
- Restrictions on package size and weight, as well as customer driven operational requirements, limited the ability to use external impact limiters As a result, earlier design was challenged by high impact decelerations during 9-meter drops Small inelastic strains in closure seal region raised concerns regarding the seal performance and leakage rate of the package (RAI 4-1)
- Closure lid seals were potentially vulnerable to high temperatures during 10 CFR 71 fire accident (after considering the deformed shape of package following drop and puncture events)
a generation ahead by design 5
Reasons for Change in Package Design (Contd)
- New design uses stress-based acceptance criteria per ASME Sec. III, Subsection NB Well established approach for structural qualification of transport casks Allows use of higher strength steel material for containment boundary Total thru-wall thickness of closure flange reduced commensurately to create more space/opportunity for energy absorbing crush zones
- New design makes more efficient use of allowable package size and weight to reduce impact decelerations during 9-meter drops Lower impact g-loads combined with higher strength containment boundary materials provide the basis for a more reliable and better performing package seal
- New design incorporates insulating material to protect the closure lid seals from high temperature exposure
a generation ahead by design Package Overview
- Contents (No change in Part 71 application)
Non-Fuel Radioactive Waste (NFW) in solid form from segmented power reactor Activated non-dispersible solids with fixed and non-fixed surface contamination Maximum Permissible 60Co Activity: 3.6E+15 Bq
- Package Performance (No change in Part 71 application)
Maximum heat load: 1.75 kW Maximum pressure: 5 psig Leakage Rate Acceptance Criteria based on Containment Analysis ALARA measures implemented via shielding materials, operating procedures and remotely actuated cask closure lid locking system 6
Holtec copyrighted material
a generation ahead by design
- Maintained overall shielding thicknesses on top, bottom and sides
- Internal dimensions (clearance and BFA tanks and cassettes unchanged)
- Size, location and material of lifting trunnions (lift capacity unchanged)
- Maintained remotely actuated locking mechanism
- Inner (containment) and outer (testing) elastomeric seals (unchanged) 7 Holtec copyrighted material Package Overview (Contd)
a generation ahead by design Package Overview (Contd)
- Packaging Components No changes to BFA-Tank Cassette or BFA-Tank 8
BFA-Tank Cassette - Steel (Container for NFW)
BFA-Tank - Steel (Container for BFA-Tank Cassette)
Note: Dimensions in millimeters Holtec copyrighted material
a generation ahead by design Package Overview (Contd)
- Packaging Components (Contd)
Revised design for HI-STAR ATB 1T Cask/Overpack 9
Overpack - Steel (Container for Waste Package - NFW, BFA-Tank Cassette and BFA-Tank)
Earlier Design New Design Holtec copyrighted material
a generation ahead by design Specific Design Enhancements 10 PROPRIETARY Holtec copyrighted material
a generation ahead by design Safety Evaluations (Thermal)
- Methodology described in HI-STAR ATB 1T SAR Chapter 3 (No change in Part 71 application)
ANSYS-Fluent CFD Code Three dimensional (3-D) modeling Heat applied as a volumetric uniform heat source within the BFA-Tank
- Models will be modified to accord with the new design
- Acceptance criteria (No change in Part 71 application)
Package metallic components limits as specified in the SAR for temperature and pressure Containment boundary seal temperature limits not exceeded Containment boundary seal temperature limits to be modified based on latest vendor data 11 Holtec copyrighted material
a generation ahead by design Safety Evaluations (Containment)
- Methodology described in HI-STAR ATB 1T SAR Chapter 4 (No change in Part 71 application)
Satisfaction of containment criteria, expressed as leakage rate acceptance criterion ensures package will not exceed allowable release limits Leakage rates determined in accordance with:
ANSI N14.5, American National Standard for Radioactive Materials - Leakage Tests on Packages for Shipment (2014), and NUREG/CR-6487, Containment Analysis for Type B Packages Used to Transport Various Contents (1996)
Source term - all source activity is assumed to be Co-60
- Allowable leakage rate calculations may be revised to include modified inputs from new design, as required
- Acceptance criteria (No change in Part 71 application):
10 CFR 71 allowable radioactive release limits 12 Holtec copyrighted material
a generation ahead by design Safety Evaluations (Shielding)
- Methodology described in HI-STAR ATB 1T SAR Chapter 5 (No change in Part 71 application)
MCNP shielding calculations (dose rates)
Isotopic specific activities Wide variety source region geometries
- No change to existing shielding models Sensitivity studies to show dose rates at modified cask corners do not exceed limits
- Acceptance criteria (No change in Part 71 application):
Normal Conditions of Transport: 10 CFR 71.47 Hypothetical Accident Conditions: 10 CFR 71.51 13 Holtec copyrighted material
a generation ahead by design Safety Evaluations (Criticality)
- Exempt from fissile material classification per 10CFR71.15 (No change in Part 71 application) 14 Holtec copyrighted material
a generation ahead by design Safety Evaluations (Structural)
- Methodology described in HI-STAR ATB 1T SAR Chapter 2 (Revised in Part 71 application)
- Major change is switch to stress-based acceptance criteria (ASME NB) from strain-based acceptance criteria (ASME EE &
FF) for cask containment boundary under Hypothetical Accident Conditions (i.e., 9-meter free drop and 1-meter puncture drop)
Analysis approach remains the same (i.e., 3-D LS-DYNA finite element analysis), only the cask model has changed
- For Normal Conditions of Transport, there are no changes to the structural analysis methodology or acceptance criteria Input data/models have been updated to reflect new cask design 15 Holtec copyrighted material
a generation ahead by design Safety Evaluations (Structural) (Contd)
- Acceptance Criteria for Cask Containment (Revised in Part 71 application):
Normal Conditions of Transport (NCT) - Under NCT, the containment base plate, the containment side walls, the top flange, the closure lid, and the cask lid locking system (i.e., containment components) shall be designed to meet the Level A stress intensity limits per ASME Section III, Subsection NB for all loading conditions.
Hypothetical Accident Condition (HAC) - Under HAC of Transport, the containment components shall be designed to meet the Level D stress limits per ASME Section III, Subsection NB for all loading conditions.
- Acceptance Criteria for Cask Dose Blocker Structure (DBS) (No change in Part 71 application):
Under NCT drops, it must be demonstrated that there is no gross yielding (substantial loss of material) in the DBS components.
Under HAC drops, the DBS is required to remain attached to the Packages Containment Boundary.
16 Holtec copyrighted material
a generation ahead by design Safety Evaluations (Structural) (Contd)
- Acceptance Criteria for BFA-Tanks and BFA-Tank Cassettes (No change in Part 71 application)
BFA-Tank walls including the top and bottom plates must not be subject to gross failure under the postulated normal and hypothetical accidental conditions BFA-Tank Cassette top and bottom plates must remain in position under normal conditions; no buckling or gross failure of corner tie-rods
- LS-DYNA Finite Element (FE) Models
- Cask FE model revised in accordance with new design
- No changes required to BFA-Tank/Cassette models 17 Holtec copyrighted material
a generation ahead by design Structural Analysis Model & Results 18 PROPRIETARY Holtec copyrighted material
a generation ahead by design Licensing Path Forward
- New Part 71 Application Input from RSIs and RAIs Input from meetings and NRC feedback Major changes to Overpack Design and Structural Acceptance Criteria
- Target Submittal Date: April 2019 19 Holtec copyrighted material
a generation ahead by design 20 End of Presentation Holtec copyrighted material