ML23181A130

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RT-100 Response to U.S. NRC Clarification Questions
ML23181A130
Person / Time
Site: 07109365
Issue date: 06/20/2023
From: Shakhatreh A
Robatel Technologies
To:
Office of Nuclear Material Safety and Safeguards, Document Control Desk
Shared Package
ML23181A127 List:
References
Download: ML23181A130 (1)
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Text

(Non-Proprietary Version)

Response to U.S. NRC Clarification Questions Docket No. 71-9365 Model No. RT-100 Package June 20, 2023 By: Abdulsalam Shakhatreh Robatel Technologies, LLC 5115 Bernard Dr., Suite 304 Roanoke, VA 24018 For: U.S. Nuclear Regulatory Commission Attn: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852

Subject:

Robatel Technologies responses to address the U.S. NRC clarification questions dated May 31st, 2023, on RAIs response letter (ADAMS Accession No. ML23143A180) for review of the Model No. RT-100 Package, Docket No. 71-9365 Clarification calls record:

May 31st, 2023, 11:00 AM - 12:26 PM June 6th, 2023, 2:00 PM - 3:10 PM Robatel: Abdulsalam Shakhatreh and Jared Bower Robatel: Abdulsalam Shakhatreh NRC: William Allen, Janine Smith, and Yong Kim NRC: William Allen and Janine Smith Orano: Andy Langston June 15th, 2023, 9:30 AM - 10:30 AM Robatel: Abdulsalam Shakhatreh NRC: William Allen and Janine Smith Responses to the clarifications are grouped by chapter number and title from the Safety Analysis Report (SAR). Where applicable, this response refers to locations in the RT-100 SAR where revised information can be located.

Page 1 of 10

(Non-Proprietary Version)

STRUCTURAL Clarification Question on RAI 2.1 Response (ADAMS Accession No. ML23143A180)

The response does not demonstrate how evaluating cold conditions of normal conditions of transport (NCT) using both a maximum internal pressure and decay heat results in the most unfavorable cask stresses. It simply explains what was done, which is already presented in the SAR.

The objective of the NCT Cold Case (@ -40 deg. F) in Table 1 of RG 7.8 is to maximize the package contraction. The applicant is using a maximized internal pressure and including decay heat, both of which are in conflict with the recommended NCT Cold Case combination. Per SAR Table 2.6.7-2, the minimum factor of safety for Cold conditions is 2.0, so not a lot of margin.

Verify the following in the applicants response:

  • 182.71 kPa is reported in the SAR as 26.5 psia, not psig, as cited in the response.
  • SAR Table 6-1 is cited but could not be found; was this intended to be Tables 2.6.7-1 and -2?

Response to clarification question on RAI 2.1 This clarification below expands on the Robatels response to RAI 2.1 in the RAI response letter dated May 19th, 2023 (ADAMS Accession No. ML23143A180). An extreme cold case is run for the NCT end drop. This case assumes -40°C uniformly applied to the model with no internal heat generation and all other boundary conditions remain the same. Below is an excerpt from SAR Table 2.6.7-2, NCT End Drop Stress Summary with the results of the -40°C extreme cold case. The results show that the hot case bounds the cold cases, where the margin of safety for the extreme cold case is much higher than the hot case.

Table 1. NCT End Drop Stress Summary with Extreme Cold Case (SAR, Table 2.6.7-2)

FLANGE MPa MPa MPa MPa MPa MS Inside 48.0 24.1 -219.4 267.4 413.7 0.5 HOT Pm + Pb + Q Center 12.9 -5.7 -23.8 36.6 413.7 10.3 Outside 74.0 34.2 -53.9 127.9 413.7 2.2 Inside 32.8 -42.6 -105.1 137.9 413.7 2.0 COLD Pm + Pb + Q Center 14.2 2.1 -24.1 38.3 413.7 9.8 Outside 92.7 71.4 -36.7 129.4 413.7 2.2 Inside 0.1 -2.0 -7.0 7.1 413.7 57.5 EXTREME COLD Pm + Pb + Q Center 4.4 -1.2 -14.6 19.1 413.7 20.7 Outside 74.3 28.6 4.9 69.4 413.7 5.0 Below are corrections to three errors in the previous response to RAI 2.1 (ADAMS Accession No. ML23143A180),

  • The MNOP unit reported in parenthesis was incorrect. The correct unit is 26.5 psia.

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  • The reference to SAR Table 6-1 was incorrect. The correct references are SAR Tables 2.6.7-1 and 2.6.7-2.

Additionally, SAR section 2.6.7.2.2 was revised to state that the extreme cold condition at -40°C without internal heat load was evaluated and considered.

SAR Impact RT-100 SAR, Revision 10 update to Section 2.6.7.2.2.

Clarification Question on RAI 2.2 Response (ADAMS Accession No. ML23143A180)

The response does not clarify the maximum internal cask pressure employed in the various NCT evaluations and the hypothetical accident conditions (HAC) fire accident. The basis of the concern is what exact pressure values are employed in these FEM analyses. It is noted that Sections 7.2.2 and 8.2.3 of Calculation RTL-001-CALC-ST-0402, Rev. 0, cite the 35 psig (241 kPa) and 85.3 psig (588 kPa) pressures as being employed in the NCT and HAC analyses, respectively. It would be helpful if in the SAR these numerical values were specifically stated as being employed in the analyses.

Verify the following in the applicants response:

  • It is stated that all pressure values presented in the SAR provide parenthetical psig or psia values, although SAR Section 2.6.1.1 and 3.3.2.5 cite both psig and psia values for the 342.7 kPa value
  • It is stated that 250 kPa is employed in lieu of 241 kPa in some cases for conservatism, however Table 2.13.3-1, reports 250 kPa as equivalent to 35 psig, which is what 241 kPa is also cited as being. (A pressure of 250 kPa is not found in the RTL-001-CALC-ST-0402 calculations.)

Response to clarification question on RAI 2.2 According to calculation note RTL-001-CALC-ST-0402, Rev. 4, Sections A.4 and 7.2.2, 35 psig (241 kPa) and 85.3 psig (588 kPa) pressures were employed in the NCT and HAC finite element analyses, respectively.

Refer to the RT-100 SAR, Revision 10, Sections 2.6.1.1 and 2.7.1 for updates to clarify this point.

Additionally, the following corrections were made in RT-100 SAR, Revision 10,

  • Removed the psig unit reported in parentheses in Sections 2.6.1.1 and 3.3.2.5.
  • Corrected references in Sections 2.13.2.1.1 and 2.13.2.1.3.
  • Deleted the parenthesized 35 psi pressure value next to the applied internal pressure 250 kPa in Tables 2.13.3-1 and 2.13.3-2.

Impact RT-100 SAR, Revision 10 updates to Sections 2.6.1.1, 2.7.1, 2.13.2.1.1, 2.13.2.1.3, Table 2.13.3-1, Table 2.13.3-2, and 3.3.2.5.

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Clarification Question on RAI 2.3 Response (ADAMS Accession No. ML23143A180)

The response does not specifically demonstrate how the omission of thermal expansion effects in the evaluation of HAC drop conditions with hot ambient conditions results in the most unfavorable cask stresses. It provides an explanation and rationale as to why the thermal effects are not included.

Based primarily on the SRP section 2.4.6.1, which states that thermal stresses should be present during this HAC drop conditions, it does not appear that the thermal stress is being considered as a self-relieving secondary stress for the impact conditions, so should be included in the stress evaluation.

It is noted that the last justification points cite Appendix F, F-1341.1 and F-1342(a), which are applicable only to plastic analyses, while this package employs an elastic analysis model.

Response to clarification question on RAI 2.3 Below is the updated response to RAI 2.3 that was provided previously (ADAMS Accession No. ML23143A180).

The cask body analysis is documented in calculation RTL-001-CALC-ST-0402. The logic for determining stress criteria used to qualify the RT-100 as a containment vessel is:

  • The RT-100 is limited to a maximum of 3000 A2. From NUREG/CR-6407, Table 4, the RT- 100 is transportation Category II.
  • From the ASME code definition, Service Level A is equivalent to Normal Conditions and Service Level D is equivalent to Accident Conditions. For Service Level D, Subsection ND invokes the requirements from ASME Section III, Appendix F.

o From RG 7.6, secondary stress means a stress that is self-limiting. Thermal stresses are considered to be secondary stresses since they are strain-controlled rather than load-controlled, and these stresses decrease as yielding occurs.

o From RG 7.6, C. Regulatory Position 6. Under accident conditions, the value of the stress intensity resulting from the primary membrane stresses should be less than the lesser value of 2.4Sm and 0.7Su, (ultimate strength); and the stress intensity resulting from the sum of the primary membrane stresses and the primary bending stresses should be less than the lesser value of 3.6Sm and Su. These stress allowables coincide with ASME Section III, Appendix F (F-1332).

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  • From ASME Section III, Appendix F, Table F-1200-1, General Note - the following design rules shall be followed: (1) Level D self-relieving stresses need not be considered unless specified within a specific section of Nonmandatory Appendix F.
  • From Appendix F, F-1400 Vessels: The rules given in F-1330 and F-1340 shall be used for evaluation of vessels for loads which Service Level D are specified. The RT-100 follows the rules of F-1330 acceptance criteria using elastic system analysis.
  • From Appendix F, F-1332, (a): Neither peak stresses nor stress results from thermal expansion within the support need to be evaluated.

Therefore, the RT-100 stress analysis follows the guidance RG 7.6 for ASME Service Level D and does not include a thermal stress evaluation for HAC.

Proprietary Information Content Withheld Under 10 CFR 2.390(b)

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Since the SAR does not provide a thorough discussion of the effects of thermal expansion during HAC, the discussion in Section 2.7.4.2 is updated.

SAR Impact RT-100 SAR, Revision 10 update to Section 2.7.4.2.

Clarification Question on RAI 2.8 Response (ADAMS Accession No. ML23143A180)

The evidence provided in the response to ensure that the stated minimum horizontal gap at all lid closure bolts is achieved prior to shipment and during transport to ensure that shear load transfer to the lid closure bolts is circumvented is not conclusive.

The applicant states that alignment pins are used to facilitate lid placement during installation. A review of the SAR dwgs. reveals that only one pin per lid is employed, which would allow the lid to rotate about this pin, possibly allowing the lid bolt holes to be non-concentric with the bolts/threaded bolt holes.

Tables 2 and 4 provide lid hole versus bolt edge dimensional information. The information presented seems to be the result of assuming the expansion or contraction of the bolt hole vs. the bolt, assuming they are initially concentric. The concern is the radial expansion or contraction of the lid toward the bolt face, which is not captured in this table. Please recalculate and provide the revised results.

Response to clarification question on RAI 2.8 The thermal expansion/contraction study was revised to include an alternative calculation of the radial expansion/contraction of the lid toward the bolt face to address the clarification question.

r = r x (1 + T)

where, r = Final radius at temperature (mm) r = Initial radius (mm)

= Coefficient of thermal expansion (1/°C)

T = Change in temperature, T - T (°C)

As documented in Table 2, the maximum initial clearance between the primary lid and cask cavity is 1.4825 mm. The final clearance during NCT and HAC expansions are 1.4837 mm and 1.4854 mm, respectively.

Additionally, the final clearance between the lid and cavity during the cold case contraction is 1.4812 mm.

As documented in Table 3, the final clearance between the bolt shank and lid hole is 2.0068 mm and 2.029 mm during NCT and HAC expansions. Additionally, the final clearance between the shank and hole during the cold case contraction is 1.9929 mm. Therefore, the clearance between the primary lid and the cask cavity is less Page 6 of 10

(Non-Proprietary Version) than the clearance between the primary lid M48 bolt and bolt hole during thermal expansion and contraction cases.

Table 2. Primary Lid Vs. Cavity Parameter Unit NCT Expansion1 HAC Expansion2 Contraction3 Initial temperature °C 21.1 21.1 21.1 Final temperature of cavity °C 71 137 -36 Final temperature of lid °C 71 137 -36 Coefficient of thermal expansion lid 1/°C 1.62E-05 1.66E-05 1.48E-05 Coefficient of thermal expansion cavity 1/°C 1.62E-05 1.66E-05 1.48E-05 Proprietary Information Content Withheld Under 10 CFR 2.390(b)

Initial gap mm 1.4825 1.4825 1.4825 Proprietary Information Content Withheld Under 10 CFR 2.390(b)

Final gap between lid and cavity mm 1.4837 1.4854 1.4812 Table 3. Primary Lid Hole Vs. Bolt Parameter Unit NCT Expansion HAC Expansion Contraction Initial temperature °C 21.1 21.1 21.1 Final temperature of bolt °C 70 91.9 -34.9 Final temperature of lid °C 71 137 -36 Thermal expansion coefficient lid 1/°C 1.62E-05 1.66E-05 1.48E-05 Thermal expansion coefficient bolt 1/°C 1.21E-05 1.24E-05 1.11E-05 Proprietary Information Content Withheld Under 10 CFR 2.390(b)

Initial gap mm 2 2 2 Proprietary Information Content Withheld Under 10 CFR 2.390(b)

Final gap between bolt hole and shank mm 2.0068 2.0290 1.9929 1

Thermal expansion coefficients at 100 from Table 2.2.1-1 of the RT-100 SAR.

2 Thermal expansion coefficients at 150 from Table 2.2.1-1 of the RT-100 SAR.

3 Thermal expansion coefficients are interpolated at -40 from Table 2.2.1-1 of the RT-100 SAR.

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Table 4 shows the alternative calculation of the primary lid expansion/contraction toward the bolt face as requested in the clarification question.

Table 4. Primary Lid Vs. Bolt (Alternative Calculation)

Parameter Unit NCT Expansion HAC Expansion Contraction Initial temperature °C 21.1 21.1 21.1 Final temperature of lid °C 71 137 -36 Thermal expansion coefficient lid 1/°C 1.62E-05 1.66E-05 1.48E-05 Proprietary Information Content Withheld Under 10 CFR 2.390(b)

Final gap between bolt hole and shank mm 2.0058 2.0289 2.0112 Table 5 and Table 6 show the bolt clearance calculations based on the original expansion/contraction calculation of the primary lid bolt hole vs. bolt and the alternative calculation of the primary lid expansion/contraction towards the bolt face. Table 5 and Table 6 demonstrate that a minimum bolt clearance of 0.512 mm is maintained to prevent loading the primary lid bolts in shear.

Table 5. Bolt Clearance Using Primary Lid Hole Vs. Bolt Calculations (Original Calculation)

Parameter Unit NCT Expansion HAC Expansion Contraction Gap between lid and cask body mm 1.4837 1.4854 1.4812 Gap between bolt and bolt hole mm 2.0068 2.0290 1.9929 Bolt clearance mm 0.5231 0.5436 0.512 Table 6. Bolt Clearance Using Primary Lid Vs. Bolt Calculations (Alternative Calculation)

Parameter Unit NCT Expansion HAC Expansion Contraction Gap between lid and cask body mm 1.4837 1.4854 1.4812 Gap between bolt and bolt hole mm 2.0058 2.0289 2.0112 Bolt clearance mm 0.5221 0.5435 0.530 As documented in Table 7, the maximum initial clearance between the secondary lid and primary lid interface is 1.4980 mm. The final clearance during NCT and HAC expansions are 1.4992 mm and 1.5009 Page 8 of 10

(Non-Proprietary Version) mm, respectively. Additionally, the final clearance between the lid interfaces during the cold case contraction is 1.4668 mm. As documented in Table 8, the final clearance between the bolt shank and lid hole is 2.0055 mm and 2.0217 mm during NCT and HAC expansions. Additionally, the final clearance between the shank and hole during the cold case contraction is 1.9943 mm. Therefore, the clearance between the secondary and primary lid interface is less than the clearance between the secondary lid M36 bolt and bolt hole during thermal expansion and contraction cases.

Table 7. Secondary Lid Vs. Primary Lid Interface Parameter Unit NCT Expansion HAC Expansion Contraction Initial temperature °C 21.1 21.1 21.1 Final temperature of cavity °C 71 137 -36 Final temperature of lid °C 71 137 -36 Coefficient of thermal expansion secondary lid 1/°C 1.62E-05 1.66E-05 1.48E-05 Coefficient of thermal expansion primary lid 1/°C 1.62E-05 1.66E-05 1.48E-05 Proprietary Information Content Withheld Under 10 CFR 2.390(b)

Initial gap mm 1.4980 1.4980 1.4980 Proprietary Information Content Withheld Under 10 CFR 2.390(b)

Final gap between lid and cavity mm 1.4992 1.5009 1.4668 Table 8. Secondary Lid Hole Vs. Bolt Parameter Unit NCT Expansion HAC Expansion Contraction Initial temperature °C 21.1 21.1 21.1 Final temperature of bolt °C 70 91.9 -34.9 Final temperature of lid °C 71 137 -36 Thermal expansion coefficient lid 1/°C 1.62E-05 1.62E-05 1.48E-05 Thermal expansion coefficient bolt 1/°C 1.21E-05 1.24E-05 1.11E-05 Proprietary Information Content Withheld Under 10 CFR 2.390(b)

Initial gap mm 2 2 2 Proprietary Information Content Withheld Under 10 CFR 2.390(b)

Final gap between bolt hole and shank mm 2.0055 2.0217 1.9943 Table 9 shows the alternative calculation of the secondary lid expansion/contraction toward the bolt face as requested in the clarification question.

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Table 9. Secondary Lid Vs. Bolt (Alternative Calculation)

Parameter Unit NCT Expansion HAC Expansion Contraction Initial temperature °C 21.1 21.1 21.1 Final temperature of lid °C 71 137 -36 Thermal expansion coefficient lid 1/°C 1.62E-05 1.62E-05 1.48E-05 Proprietary Information Content Withheld Under 10 CFR 2.390(b)

Final gap between bolt hole and shank mm 2.0043 2.0242 2.0062 Table 10 and Table 11 show the bolt clearance calculations based on the original expansion/contraction calculation of the secondary lid bolt hole vs. bolt and the alternative calculation of the secondary lid expansion/contraction towards the bolt face. Table 10 and Table 11 demonstrate that a minimum bolt clearance of 0.5063 mm is maintained to prevent loading the secondary lid bolts in shear.

Table 10. Bolt Clearance Using Secondary Lid Hole Vs. Bolt Calculations (Original Calculation)

Parameter Unit NCT Expansion HAC Expansion Contraction Gap between primary and secondary lids mm 1.4980 1.4980 1.4680 Gap between bolt and bolt hole mm 2.0055 2.0217 1.9943 Bolt clearance mm 0.507 0.5237 0.5263 Table 11. Bolt Clearance Using Secondary Lid Vs. Bolt Calculations (Alternative Calculation)

Parameter Unit NCT Expansion HAC Expansion Contraction Gap between primary and secondary lids mm 1.4980 1.4980 1.4980 Gap between bolt and bolt hole mm 2.0043 2.0242 2.0062 Bolt clearance mm 0.5063 0.5262 0.5082 Additionally, SAR Sections 2.13.2.1.1 and 2.13.2.1.3 were updated to state that tolerance stackup based on actual dimensions and thermal expansion/contraction calculations were performed to ensure bolt clearance is not eliminated during normal and accident conditions.

Impact RT-100 SAR, Revision 10 update to Sections 2.13.2.1.1 and 2.13.2.1.3.

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