ML23067A077
| ML23067A077 | |
| Person / Time | |
|---|---|
| Site: | 07201004 |
| Issue date: | 03/08/2023 |
| From: | Narayanan P TN Americas LLC |
| To: | Office of Nuclear Material Safety and Safeguards, Document Control Desk |
| Shared Package | |
| ML23067A076 | List: |
| References | |
| E-62133, EPID L-2022-LLA-00, CAC 001028 | |
| Download: ML23067A077 (1) | |
Text
March 8, 2023 E-62133 U. S. Nuclear Regulatory Commission Columbia Office 7160 Riverwood Drive Attn: Document Control Desk Columbia, MD 21046 One White Flint North Tel: (410) 910-6900 11555 Rockville Pike
@Orano_USA Rockville, MD 20852
Subject:
Second Supplemental Response to Request for Additional Information - Application for Amendment 18 to Standardized NUHOMS Certificate of Compliance No. 1004 for Spent Fuel Storage Casks, Revision 5 (Docket No. 72-1004, CAC No. 001028, EPID: L-2022-LLA-0079)
Reference:
[1] E-61864, Response to Request for Additional Information -
Application for Amendment 18 to Standardized NUHOMS Certificate of Compliance No. 1004 for Spent Fuel Storage Casks, Revision 2 (Docket No. 72-1004, CAC No. 001028, EPID: L-2022-LLA-0079),
dated January 20, 2023 TN Americas LLC (TN) hereby submits a supplement to Reference [1], above, that provides additional clarifying information associated with the responses to certain shielding RAIs. In addition, a revision was made in CoC Appendix A, Inspections, Tests, and Evaluations, Section 4.2, to provide more specificity to the requirements for horizontal storage module (HSM) concrete temperature testing.
The NRC and TN held a clarification call on February 24, 2023 for the purpose of clarifying TNs responses to certain shielding RAIs. As a result, TN is providing supplemental information associated with RAIs 6-4, 6-7, 6-10, 6-11, 6-13, and 6-14.
Enclosure 2 provides the aforementioned RAIs and supplemental responses as a result of the clarification call. Enclosure 3 provides a description of the Amendment 18 change not related to RAIs. Enclosure 4 provides a complete revision to the CoC Appendix A Inspections, Tests and Evaluations (ITE) with proposed changes tracked.
Enclosure 5 provides a complete revision to the CoC Appendix B Technical Specifications (TS) with proposed changes tracked.
The proprietary version of the Updated Final Safety Analysis Report (UFSAR) changed pages associated with Amendment 18 are included as Enclosure 6, with a footer on each changed page annotated as 72-1004 Amendment 18, Revision 5, March 2023, and changes indicated by italicized text and revision bars. The changes are further annotated with gray shading or a gray box enclosing an added section, as well as a footer to distinguish the Amendment 18, Revision 5 changes from previous Amendment 18 changes. Revised drawings show alpha-numeric revision numbers and clouds surrounding the changed drawing information. The public version of these UFSAR changed pages and drawings is provided as Enclosure 7.
Document Control Desk E-62133 Page 2 of 2 Certain portions of this submittal include proprietary information, which may not be used for any purpose other than to support the NRC staffs review of the application. In accordance with 10 CFR 2.390, TN Americas LLC is providing an affidavit, Enclosure 1, specifically requesting that this proprietary information be withheld from public disclosure.
Should you have any questions regarding this submittal, please do not hesitate to contact Mr.
Douglas Yates at 434-832-3101 or me at 410-910-6859.
Sincerely, Prakash Narayanan Chief Technical Officer cc: Chris Allen (NRC), Project Manager, Storage and Transportation Licensing Branch Division of Fuel Management
Enclosures:
- 1. Affidavit Pursuant to 10 CFR 2.390
- 2. RAIs and Responses
- 3. Description of Amendment 18 Changes Not Related to RAIs
- 6. Proposed Amendment 18, Revision 5 Changes to the Standardized NUHOMS System Updated Final Safety Analysis Report (Proprietary Version)
- 7. Proposed Amendment 18, Revision 5 Changes to the Standardized NUHOMS System Updated Final Safety Analysis Report (Public Version)
Enclosure 1 to E-62133 AFFIDAVIT PURSUANT TO 10 CFR 2.390 TN America~ LLC )
State ofMarylaful) ss.
County of Howard )
I, Prakash Narayanan, depose and say that I am the Chief Technical Officer of TN Americas LLC, duly authorized to execute this affidavit, and have reviewed or caused to have reviewed the information that is identified as proprietary and referenced in the paragraph immediately below. I am submitting this affidavit in conformance with the provisions of 10 CFR 2.390 of the Commission' s regulations for withholding this information.
The information for which proprietary treatment is sought meets the provisions of paragraph (a) (4) of Section 2.390 of the Commission's regulations. The information is listed below:
- Enclosure 6 - Portions of Proposed Changes to the Standardized NUHOMS System Updated Final Safety Analysis Report This document has been appropriately designated as proprietary.
I have personal knowledge of the criteria and procedures utilized by TN Americas LLC in designating information as a trade secret, privileged or as confidential commercial or financial information.
Pursuant to the provisions of paragraph (b) (4) of Section 2.390 of the Commission's regulations, the following is furnished for consideration by the Commission in determining whether the information sought to be withheld from public disclosure, included in the above referenced document, should be withheld.
- 1) The information sought to be withheld from public disclosure involves portions of the UFSAR, all related to the design of the Standardized NUHOMS dry spent fuel storage system, which are owned and have been held in confidence by TN Americas LLC.
- 2) The information is of a type customarily held in confidence by TN Americas LLC, and not customarily disclosed to the public. TN Americas LLC has a rational basis for determining the types of information customarily held in confidence by it.
- 3) Public disclosure of the information is likely to cause substantial harm to the competitive position of TN Americas LLC, because the information consists of descriptions of the design of dry spent fuel storage systems, the application of which provide a competitive economic advantage. The availability of such information to competitors would enable them to modify their product to better compete with TN Americas LLC, take marketing or other actions to improve their product' s position or impair the position of TN Americas LLC ' s product, and avoid developing similar data and analyses in support of their processes, methods or apparatus.
Further the deponent sayeth not.
Prakash Narayanan Chief Technical Officer, TN Americas LLC Subs ibed and sworn before me this 1 day of March, 2023 .
Notary Pu I c MAAY ANNE D ATIENZA Notary Public My Commission Expires .2_/s2:::::_;__;):Q-;)._ c:; P-.rir,;; Arundel County Maryland My Commission Expires March 02 , 2025 Page 1 of 1
RAIs and Responses Enclosure 2 to E-62133 RAI 6.4:
Justify the modification of the dose rate limits for the transfer casks and the storage modules to combine the 24PTH-S-LC with the 24PTH-S and 24PTH-L in the transfer cask and in the HSM-H.
It is not clear that the dose rate limits for the 24PTH-S and 24PTH-L DSCs for both the transfer cask and the HSM-H are also appropriate limits for the 24PTH-S-LC. Given the differences in the DSCs and the HSM-H versus the Standardized HSM, appropriate limits for the 24PTH-S-LC would be significantly less than for the 24PTH-S and 24PTH-L, by a factor of three on the radial transfer cask surface and about a factor of ten on the HSM-H front bird screens. Thus, the proposed changes would result in non-conservative dose rate limits for the 24PTH-S-LC DSC in the transfer cask and in the HSM-H storage module. The staff further notes that the dose rate limits for the 24PTH-S-LC DSC have been kept separate from the limits for the 24PTH-S and 24PTH-L DSCs from the time the 24PTH DSC was added to the Standardized NUHOMS system. So, it is not clear what has changed to support combining the limits for the transfer cask and using the limits for the 24PTH-S and 24PTH-L in the HSM-H for the 24PTH-S-LC in the HSM-H.
This information is needed to confirm compliance with 10 CFR 72.236(b) and (d) and ensure the system is sufficient to facilitate licensee compliance with 10 CFR 20.1101 and 20.1201(a) and 10 CFR 72.126(a)(6).
Original Response to RAI 6.4:
Dose rates limits for the 24PTH system are reported in CoC 1004 Appendix A Inspections, Tests, and Evaluations (ITE) Section 3.2 for the transfer cask (TC) and in Section 3.3.2 for the Standardized HSM and HSM-H.
For the 24PTH-S-LC Dry Shielded Canister (DSC) in the Standardized Horizontal Storage Module (HSM), the dose rate limits at the three locations defined in CoC 1004 Appendix A ITE Section 3.3.1 are:
- 600 mrem/hr at HSM front bird screen
- 105 mrem/hr at outside door and
- 400 mrem/hr at end shield wall exterior while for the 24PTH-S and 24PTH-L DSC as 24PTH DSC in HSM-H, the dose rate limits at the three locations are:
- 1400 mrem/hr at HSM front bird screen
- 5 mrem/hr at outside door and
- 20 mrem/hr at end shield wall exterior Page 1 of 30
RAIs and Responses Enclosure 2 to E-62133 The dose rates are developed based on the calculated maximum dose rates reported in UFSAR Table P.5-2 for the 24PTH-S-LC DSC and Table P.5-1 for the 24PTH-L DSC (the 24PTH-S DSC being bounded by the 24PTH-L DSC).
For the TC, a single set of dose rate limits is reported per DSC. As such, the dose rate limits correspond to the 24PTH-L DSC dose rates shown in UFSAR Table P.5-3 (and Table P.5-3a),
which bound those of the 24PTH-S-LC DSC shown in UFSAR Table P.5-5 (and Table P.5-5a).
The 24PTH TC dose rate limits are:
- 1200 mrem/hr, axial surface dose rate
- 1500 mrem/hr, radial surface dose rate The 24PTH-S-LC DSC loading is limited to HLZC #5 (maximum fuel assembly heat load of 1.5 kW), while the 24PTH-S and 24PTH-L DSC can be loaded with HLZC #2 (maximum fuel assembly heat load of 2.0 kW), per the CoC 1004 UFSAR Appendix B Amendment 18 Technical Specifications (TS).
Note that 10 CFR Part 72 does not specify dose rate limits for dry storage system surfaces nor at set distances from dry storage system surfaces. The Amendment 18 TS appropriately define the loading configurations for each subset DSC of the 24PTH DSC system and dose rate limits are appropriately developed in CoC 1004 Appendix A Amendment 18 ITE for the licensee to demonstrate compliance with 10 CFR 20, 10 CFR 72.104, and 10 CFR 72.106.
Original Impact:
No change as a result of this RAI.
Supplemental Response to RAI 6.4:
A TC radial surface dose rate limit for the 24PTH-S-LC DSC of 600 mrem/hr has been reestablished in the CoC 1004 Appendix A, ITE, Section 3.2 table of dose rate limits.
Supplemental Impact:
CoC 1004 Appendix A, ITE, Section 3.2 has been revised as described in the response.
Page 2 of 30
RAIs and Responses Enclosure 2 to E-62133 RAI 6.7:
Confirm that the only gaps in the DSC shield plugs with the new lead option are radial gaps (i.e.,
that there are no axial gaps too). If axial gaps are allowed, revise the drawings to show the maximum axial gaps.
The revised drawings for the DSC (Drawing No. NUH24PTH-1001-SAR, rev 7A and Drawing No. NUH24PTH-1002-SAR, rev 3A) only show radial gaps for the new lead option in the 24PTH-S-LC DSCs shield plugs (top and bottom). However, section P.4.12.3 discusses axial gaps between the lead and steel shield plug components. The drawings should show the maximum dimensions of any axial gaps. Both axial and radial gaps can be important for shielding, particularly in understanding how much the lead may deform, including under drop accident conditions, and the impacts for dose rates that deformation will have.
This information is needed to confirm compliance with 10 CFR 72.236(b) and (d).
Original Response to RAI 6.7:
A lead disc insert option is provided as an alternate to the lead pouring option for the 24PTH-S-LC DSC with a Type 3 basket. The axial gap mentioned in Section P.4.12.3 is to account for potential contact gaps, i.e., surface roughness between lead discs and adjacent surfaces. This is specific to the thermal analysis and does not reflect any pre-defined/actual axial gap in the top and bottom shield plug assemblies.
Original Impact:
No change as a result of this RAI.
Supplemental Response to RAI 6.7:
UFSAR Section P.4.12.3 has been updated to remove the additional description of the gaps and now refers directly to the primary UFSAR drawings. This eliminates any ambiguity between the drawing and the additional description offered within the text of the thermal chapter. In addition, UFSAR Drawing NUH24PTH-1002-SAR has been revised to remove indications of an axial gap between the lead and steel.
Supplemental Impact:
UFSAR Section P.4.12.3 has been revised as described in the response.
UFSAR Drawing NUH24PTH-1002-SAR has been revised as described in the response.
Page 3 of 30
RAIs and Responses Enclosure 2 to E-62133 RAI 6.10:
Provide clarification that the geometric configuration of damaged fuel does not change under accident conditions or explain how a change in the configuration is bounded by the current shielding analysis.
The shielding analysis appears to treat the damaged fuel as intact fuel. The geometric configuration of the spent fuel contents impacts the geometric distribution of the source term that can lead to increased dose rates. Page P.5-8 of the updated final safety analysis report (UFSAR) indicates that damaged fuel has no impact on dose rates. The basis and justification for that statement are not clear.
This information is needed to confirm compliance with 10 CFR 72.236(b) and (d).
Original Response to RAI 6.10:
Damaged fuel is defined in CoC 1004 Appendix B Amendment 18 Technical Specifications (TS)
Table 1-1l as assemblies containing missing or partial fuel rods, fuel rods with known or suspected cladding defects greater than hairline cracks or pinhole leaks. The extent of damage in the fuel assembly, including non-cladding damage, is to be limited such that the fuel assembly is able to be handled by normal means. Missing fuel rods are allowed. The extent of damage in the fuel rods is to be limited such that a fuel pellet is not able to pass through the damaged cladding during handling and retrievability is ensured following normal and off-normal conditions. As such, under normal and off-normal conditions, damaged fuel has no impact on dose rates as the source term would not be affected and gross axial source redistribution is not likely.
The potential impact of damaged fuel under accident conditions has been addressed, for example, in UFSAR Chapter U.5 for the 32PTH1 system (and Chapter T.5 for the 61BTH system) including assuming the damaged fuel turns to rubble. The accident scenario assumes that the neutron shield and steel neutron shield jacket (outer skin) have been torn off (see Section U.5.4.8 and Section U.11.2.5.3). While local peak dose rates are observed, the dose rates at a far distance (dose rates employed for the accident dose evaluations) are bounded by those calculated assuming intact fuel in damaged fuel locations. A similar conclusion is expected for the 24PTH system; therefore, the accident dose calculations documented in UFSAR Section P.11.2.5.3 are appropriately evaluated for all fuel conditions and show significant margin to the 10 CFR Part 72 limits for accident conditions.
UFSAR Section P.5.4.8 has been updated to reference the damaged fuel evaluation in the accident condition performed in Chapter U.5.
Original Impact:
UFSAR Section P.5.4.8 has been revised as described in the response.
Page 4 of 30
RAIs and Responses Enclosure 2 to E-62133 Supplemental Response to RAI 6.10:
CoC 1004 Appendix B, TS Table 1-1l (24PTH DSC) has been revised to remove the reference that top and bottom endcaps ensure retrievability. Ensuring retrievability was legacy wording but has now been updated with language similar to that used in the Number and Location of Damaged Assemblies row of 32PTH1 in Table 1-1aa. In addition, Table 1-1e (32PT DSC) and Table 1-1t (61BTH DSC) contain the same legacy language in the same table row pertaining to top and bottom endcaps ensuring retrievability. These two tables have also been updated accordingly.
Supplemental Impact:
CoC 1004 Appendix B, TS Tables 1-1e, 1-1l, and 1-1t have been revised as described in the response.
Page 5 of 30
RAIs and Responses Enclosure 2 to E-62133 RAI 6.11:
Revise the tables and figures in chapter P.5 of the UFSAR that describe the analysis model specifications to include the changes to the analysis models for this amendment.
While the text of chapter P.5 discusses the differences (e.g., lead density), the tables and figures in chapter P.5 are an important source for understanding the models quickly and easily.
Thus, they should also reflect the information for analysis models with the new basket (e.g.,
density for the HSLA, configuration of basket materials) and the lead in the 24PTH-S-LC DSCs top and bottom shield plugs (e.g., lead density, lead dimensions). Consistent description of the models for the different models is necessary to ensure correct and consistent understanding of the analyses.
This information is needed to confirm compliance with 10 CFR 72.236(b) and (d).
Original Response to RAI 6.11:
A note has been added to UFSAR Table P.5-14 to indicate that the lead density in top and bottom shield plug models of the 24PTH-S-LC Type 3 is 11.00 g/cm3. The lead thicknesses are shown in Drawings NUH24PTH-1002-SAR and NUH24PTH-1001-SAR, respectively, (i.e., 4.30 inches for the top shield plug and 2.50 inches for the bottom shield plug).
The other materials employed in the Monte Carlo N-Particle (MCNP) models are standard materials including high-strength low-alloy steel (HSLA) in the basket modeled as stainless steel; see the response to RAI 6.6.
Original Impact:
UFSAR Table P.5-14 has been revised as described in the response.
Supplemental Response to RAI 6.11:
The lead density in the added note to UFSAR Table P.5-14, in atom/b-cm, has been corrected.
Note that this has no impact on the dose rates results reported in the UFSAR because the incorrect value in atom/b-cm was not used in the shielding model; the density value in atom/b-cm is only reported in UFSAR Table P.5-14 for consistency with the unit convention of the table.
Supplemental Impact:
UFSAR Table P.5-14 has been updated as described in the response.
Page 6 of 30
RAIs and Responses Enclosure 2 to E-62133 RAI 6.13:
Confirm and justify the dose rate differences seen in the application for the transfer cask and HSM.
The radiation source terms and the geometry of those source terms for the spent fuel contents of the 24PTH-L and 24PTH-S-LC are not changing in this amendment. The amendment only changes the basket from the Type 2 to the Type 3 basket for both these DSC variants. The amendment also changes the lead shield plugs in the 24PTH-S-LC, reducing the lead density and reducing the minimum lead thickness in the bottom shield plug. Since only the basket is changing for the 24PTH-L, the staff expects that the impact to dose rates should be uniform for different analyzed configurations at the top and bottom axial ends of the DSC in the transfer cask and the storage module. The applicants results indicate this is the case with the exception of the transfer cask top dose rates. All transfer cask dose rates increase by 25 to 33% except the top transfer operations configuration, which only increases 4.6%. The staffs simple calculations indicate that the change across all configurations should be a uniform increase of over 20%. The staff notes the increase for the HSM-H door is higher than expected based on its simple calculations, but the staff can find that to be acceptable (as the applicants analyzed increase bounds the increase determined in the staffs evaluation).
For the 24PTH-S-LC, both the basket and the lead shield plugs are changing, with greater changes to the bottom lead shield plug (vs. the top lead shield plug). Yet, the applicants dose rate results indicate that the transfer operations configuration dose rates for the top decrease slightly. This is inconsistent with the source term and source term configuration not changing, but the shielding due to the basket and the lead shield plug decreasing. Also, a comparison of the differences in HSM door dose rates for the 24PTH-L and 24PTH-S-LC show the difference in dose rates is comparable between the two DSC variants (46% increase vs. 45% increase).
This is not consistent with differences in shielding changes between the two DSC variants. The relative increase in dose rates for the 24PTH-S-LC should be significantly higher (versus the increase seen for the 24PTH-L) given reduced shielding in not only the basket, but also in the lead shield plug (lower density and thinner minimum thickness). The staffs simple calculations indicate that the transfer cask top dose rates should increase significantly (by over 50%) and the transfer cask bottom dose rates and HSM door dose rates should also increase significantly (by 60 to 70%).
Based on the above, further justification and explanation of the dose rate changes is needed, or the analyses need to be corrected to appropriately reflect the shielding impacts due to the basket and lead shield plug changes. This is important for understanding and correctly characterizing dose rates for occupational dose assessments as well as normal, off-normal, and accident conditions doses for public dose assessments.
This information is needed to confirm compliance with 10 CFR 72.236(b) and (d) and ensure the system is sufficient to facilitate licensee compliance with 10 CFR 20.1101 and 20.1201(a) and 10 CFR 72.126(a)(6).
Page 7 of 30
RAIs and Responses Enclosure 2 to E-62133 Original Response to RAI 6.13:
Updated Final Safety Analysis Report (UFSAR) Section P.5.4.7.3 provides the analysis of the 24PTH-L DSC in the OS197FC transfer cask (TC). Results for the 24PTH-L Type 2 and 24PTH-L Type 3 are shown, respectively, in UFSAR Table P.5-3 and Table P.5-3a. Comparison of the dose rates in UFSAR Table P.5-3 and Table P.5-3ashows that side dose rate decreases by approximately 17% (1.50E+3 mrem/hr for 24PTH-L Type 2 Vs 1.25E+3 mrem/hr for 24PTH-L Type 3), while the top axial dose rate increases slightly by 4.6% (2.61E+2 mrem/hr for 24PTH-L Type 2 Vs 2.73E+2 mrem/hr for 24PTH-L Type 3) and bottom axial dose rate increases by 31%
(4.23E+3 mrem/hr for 24PTH-L Type 2 Vs 5.55E+3 mrem/hr for 24PTH-L Type 3). The last paragraph of UFSAR Section P.5.4.7.3 provides an explanation of the differences as side dose rates decrease for the Type 3 basket compared to the Type 2 basket due to the different transition rail design. However, because the basket members are generally lighter in the Type 3 basket, the end dose rates increase for the Type 3 basket compared to the Type 2 basket.
Note that, as demonstrated in UFSAR Table P.5-9 through Table P.5-11, the effect of the basket change is less pronounced for the top dose rate since the top region source is lower than that of the bottom region; furthermore, the top nozzle ends well below the top shield plug as opposed to the bottom nozzle (the bottom nozzle sits just above the bottom shield plug), as shown in UFSAR Figure P.5-8.
UFSAR Section P.5.4.7.4 provides the analysis of the 24PTH-S-LC DSC in the Standardized TC. Results for the 24PTH-S-LC Type 2 and 24PTH-S-LC Type 3 are shown, respectively, in UFSAR Table P.5-5 and Table P.5-5a. Comparison of the dose rates in UFSAR Table P.5-5 and Table P.5-5ashows that side dose rate decreases by approximately 29% (5.77E+2 mrem/hr for 24PTH-S-LC Type 2 Vs 4.10E+2 mrem/hr for 24PTH-S-LC Type 3) when the top axial dose rate is relatively similar (3.25E+1 mrem/hr for 24PTH-S-LC Type 2 Vs 3.23E+1 mrem/hr for 24PTH-S-LC Type 3), and the bottom axial dose rate increases by 41% (4.75E+3 mrem/hr for 24PTH-S-LC Type 2 Vs 6.70E+3 mrem/hr for 24PTH-S-LC Type 3). The last paragraph of UFSAR Section P.5.4.7.4 provides an explanation of the differences as side dose rates decrease for the Type 3 basket compared to the Type 2 basket due to the different transition rail design. However, because the basket members are generally lighter in the Type 3 basket, the end dose rates increase for the Type 3 basket compared to the Type 2 basket. In addition, end dose rates also increase due to modeling the machined-lead shield plug option.
Note that the lead thickness in the top shield plug is the same between Type 2 and Type 3 baskets, while lead density employed in the Type 3 is reduced (11.34 g/cm3 in the Type 2 calculation and 11.00 g/cm3 in the Type 3 calculation). The overall effect on the top total dose rate reflects the minimum change, the difference in dose rate is within the MCNP uncertainty
(). The overall effect of the change on the bottom total dose rate is more significant as the lead thickness in the Type 3 is 2.50 inches, while it is 2.75 inches in the Type 2 basket.
Original Impact:
No change as a result of this RAI.
Page 8 of 30
RAIs and Responses Enclosure 2 to E-62133 Supplemental Response to RAI 6.13:
Cask top and bottom dose rates are computed using concentric mesh tallies. The cask top axial surface dose rate shown in UFSAR Table P.5-3 is the peak dose rate at the cask top surface for the 24PTH-L Type 2 dry shielded canister (DSC) in the OS197FC TC. Table RAI 6.13-1 provides the dose rates profile as a function of mesh tallies for the 24PTH-L Type 2 DSC. The peak dose rate occurs at the annulus position (gap between DSC and TC), and Figure RAI 6.13-1 provides the plot of the cask top surface dose rates; this is similar to UFSAR Figure P.5-20. Table RAI 6.13-2 provides the dose rates profile as a function of mesh tallies for the 24PTH-L Type 3 DSC and Figure RAI 6.13-2 presents it graphically. While the dose rate ratio at the peak location, dry annulus, is 1.046 (+4.6%) between 24PTH-L Type 3 DSC and 24PTH-L Type 2 DSC, the ratio for dose rate at 40 cm tally midpoint is 1.22 (+22%) and the ratio for the average dose rates inside 90 cm is 1.15 (+15%). Table RAI 6.13-3 and Table RAI 6.13-4 provide the profiles of dose rates at cask top 1 for respectively the 24PTH-L Type 2 DSC and the 24PTH-L Type 3 DSC.
Note that Table RAI 6.13-1 and the Table RAI 6.13-3 correspond to UFSAR Table P.5-3, which only provides maximum dose rates in transfer configuration for the 24PTH-L Type 2 DSC.
Note that Table RAI 6.13-2 and Table RAI 6.13-4 correspond to UFSAR Table P.5-3a, which only provides maximum dose rates in the transfer configuration for the 24PTH-L Type 3 DSC.
Note that top 1-foot average-inside-90cm dose rates reported in Table RAI 10.1-1, for dose exposure evaluation, respectively, for the 24PTH-L Type 2 DSC and Type 3 DSC is shown on Table RAI 6.13-3 (58.8 mrem/hr rounded to 59 mrem/hr as shown in Table RAI 10.1-1) and Table RAI 6.13-4 (67.7 mrem/hr rounded to 68 mrem/hr as shown in Table RAI 10.1-1).
Table RAI 6.13-5 and Table RAI 6.13-6 provide the profiles of dose rates at cask top surface for respectively the 24PTH-L Type 2 DSC and the 24PTH-L Type 3 DSC in decontamination configuration. Figure RAI 6.13-3 and Figure RAI 6.13-4 present the plots for the dose rates shown in Table RAI 6.13-5 and Table RAI 6.13-6, respectively. It can be observed that the peak dose rate location is well inside 90 cm (at 40 cm tally midpoint) and the dose rate ratio is 1.26
(+26%). This is consistent with the dose rate ratio at the same location in transfer configuration.
Table RAI 6.13-7 and Table RAI 6.13-8 provide the profiles of dose rates at cask top surface for, respectively, the 24PTH-L Type 2 DSC and the 24PTH-L Type 3 DSC in welding configuration.
Figure RAI 6.13-5 and Figure RAI 6.13-6 present the plots for the dose rates shown in Table RAI 6.13-7 and Table RAI 6.13-8, respectively. It can be observed that the peak dose rate location is inside 90 cm (at 40 cm tally midpoint) and the dose rate ratio is 1.24 (+24%). This is consistent with the dose rate ratio at the same location in transfer configuration.
Note that Table RAI 6.13-5 and Table RAI 6.13-7 correspond to UFSAR Table P.5-4, which only provides maximum dose rates in decontamination and welding configurations for the 24PTH-L Type 2 DSC.
Note that Table RAI 6.13-6 and Table RAI 6.13-8 correspond to UFSAR Table P.5-4a, which only provides maximum dose rates in decontamination and welding configurations for the 24PTH-L Type 3 DSC.
Page 9 of 30
RAIs and Responses Enclosure 2 to E-62133 A similar trend is expected for the 24PTH-S-LC Type 2 and Type 3 DSCs in the Standardized TC. Table RAI 6.13-9 and Table RAI 6.13-10 provide the profiles of dose rates at cask top surface for, respectively, the 24PTH-S-LC Type 2 DSC and the 24PTH-S-LC Type 3 DSC in the transfer configuration. While the dose rate ratio at the peak location, dry annulus, is 0.994
(-0.6%) between 24PTH-S-LC Type 3 DSC and 24PTH-S-LC Type 2 DSC, the ratio for dose rate at 40 cm tally midpoint is 1.19 (+19%) and the ratio for the average dose rates inside 90 cm is 1.13 (+13%). Figure RAI 6.13-7 and Figure RAI 6.13-9 present the plots for the dose rates shown in Table RAI 6.13-9 and Table RAI 6.13-10, respectively.
Note that Table RAI 6.13-9 corresponds to UFSAR Table P.5-5 which only provides maximum dose rates in transfer configuration for the 24PTH-S-LC Type 2 DSC.
Note that Table RAI 6.13-10 corresponds to UFSAR Table P.5-5a which only provides maximum dose rates in transfer configuration for the 24PTH-S-LC Type 3 DSC.
Regarding horizontal storage module (HSM) door centerline dose rates, the trend is correlated to the cask bottom axial surface TC dose rates in the transfer configuration as, in the storage configuration, the DSC bottom is directed towards the HSM door. As indicated in Note 7 to UFSAR Table P.5-1, the HSM door total dose rate increases to 1.9 mrem/hr for the 24PTH-L Type 3 DSC compared to 1.3 mrem/hr for the 24PTH-L Type 2 DSC, the ratio is 1.46 (or +46%).
From UFSAR Table P.5-3 and Table P.5-3a, the dose rate ratio for cask bottom axial surface is 1.31 (or +31%) between the 24PTH-L Type 3 DSC and the 24PTH-L Type 2 DSC (5.55E+3 /
4.23E+3).
Similarly, Note 5 to UFSAR Table P.5-2 indicates the HSM door total dose rate increases to 90 mrem/hr for the 24PTH-S-LC Type 3 DSC compared to 62.2 mrem/hr for the 24PTH-S-LC Type 2 DSC; the ratio is 1.45 (or +45%). From UFSAR Table P.5-5 and Table P.5-5a, the dose rate ratio for cask bottom axial surface is 1.41 (or +41%) between the 24PTH-S-LC Type 3 DSC and the 24PTH-S-LC Type 2 DSC (6.70E+3 / 4.75E+3).
Overall, the dose rates trend is consistent throughout the transfer cask configurations when considering the dose rates profiles and the characteristics of each transfer cask configuration.
Supplemental Impact:
No change as a result of this RAI.
Page 10 of 30
RAIs and Responses Enclosure 2 to E-62133 Table RAI 6.13-1 OS197FC Transfer Cask with 24PTH-L Type 2 DSC, Top Dose Rate, Surface
- Transfer Configuration Tally Neutron Total Gamma Total Midpoint Tally Outer (cm) Radii (cm) mRem/hr 1 error mRem/hr 1 error mRem/hr 1 error 15 30 4.48E+01 0.0499 2.82E+01 0.0498 7.30E+01 0.0362 40 50 3.91E+01 0.0388 4.10E+01 0.0274 8.01E+01 0.0236 60 70 2.92E+01 0.0330 3.76E+01 0.0364 6.67E+01 0.0251 77.5 85 2.43E+01 0.0520 5.33E+01 0.0429 7.76E+01 0.0337 86 87 2.39E+01 0.1018 2.37E+02 0.0566 2.61E+02 0.0523 88.5 90 2.00E+01 0.0875 8.43E+01 0.0469 1.04E+02 0.0414 100 110 3.37E+01 0.0752 1.16E+01 0.0293 4.53E+01 0.0564 120 130 3.63E+01 0.0782 7.78E+00 0.0435 4.41E+01 0.0649 140 150 2.67E+01 0.0914 1.89E+01 0.0263 4.55E+01 0.0546 160 170 2.35E+01 0.0502 2.88E+01 0.0180 5.23E+01 0.0246 180 190 3.74E+01 0.3102 3.76E+01 0.0159 7.50E+01 0.1550 249.289 308.578 2.91E+01 0.0131 4.81E+01 0.0083 7.72E+01 0.0072 Average total 2.99E+01 0.0323 4.11E+01 0.0077 7.10E+01 0.0143 Average 90 3.06E+01 0.0203 5.33E+01 0.0193 8.39E+01 0.0144 Page 11 of 30
RAIs and Responses Enclosure 2 to E-62133 Table RAI 6.13-2 OS197FC Transfer Cask with 24PTH-L Type 3 DSC, Top Dose Rate, Surface
- Transfer Configuration Tally Neutron Total Gamma Total Midpoint Tally Outer (cm) Radii (cm) mRem/hr 1 error mRem/hr 1 error mRem/hr 1 error 15 30 6.07E+01 0.0060 4.06E+01 0.0058 1.01E+02 0.0043 40 50 4.84E+01 0.0050 5.04E+01 0.0043 9.88E+01 0.0033 60 70 3.65E+01 0.0044 4.11E+01 0.0035 7.76E+01 0.0028 77.5 85 2.70E+01 0.0046 5.69E+01 0.0151 8.39E+01 0.0103 86 87 2.46E+01 0.0084 2.48E+02 0.0378 2.73E+02 0.0344 88.5 90 2.18E+01 0.0074 8.63E+01 0.0236 1.08E+02 0.0189 100 110 3.35E+01 0.0031 1.40E+01 0.0125 4.75E+01 0.0043 120 130 3.41E+01 0.0032 8.82E+00 0.0043 4.29E+01 0.0027 140 150 2.73E+01 0.0035 1.78E+01 0.0022 4.52E+01 0.0023 160 170 2.46E+01 0.0039 2.69E+01 0.0019 5.15E+01 0.0021 180 190 2.42E+01 0.0040 3.38E+01 0.0018 5.80E+01 0.0020 249.289 308.578 2.65E+01 0.0022 4.15E+01 0.0011 6.80E+01 0.0011 Average total 2.79E+01 0.0021 3.72E+01 0.0022 6.51E+01 0.0015 Average 90 3.73E+01 0.0023 5.92E+01 0.0083 9.65E+01 0.0052 Page 12 of 30
RAIs and Responses Enclosure 2 to E-62133 Table RAI 6.13-3 OS197FC Transfer Cask with 24PTH-L Type 2 DSC, Top Dose Rate, 1 -
Transfer Configuration Tally Neutron Total Gamma Total Midpoint Tally Outer (cm) Radii (cm) mRem/hr 1 error mRem/hr 1 error mRem/hr 1 error 15 30 3.11E+01 0.0455 3.05E+01 0.0389 6.16E+01 0.0300 40 50 2.71E+01 0.0307 3.25E+01 0.0236 5.95E+01 0.0190 60 70 2.17E+01 0.0309 3.24E+01 0.0208 5.41E+01 0.0176 77.5 85 1.79E+01 0.0404 3.73E+01 0.0411 5.52E+01 0.0307 86 87 1.72E+01 0.1040 7.86E+01 0.0741 9.58E+01 0.0636 88.5 90 1.38E+01 0.0661 5.06E+01 0.0627 6.44E+01 0.0512 100 110 1.37E+01 0.0650 2.07E+01 0.0358 3.44E+01 0.0337 120 130 1.57E+01 0.0760 9.48E+00 0.0324 2.52E+01 0.0489 140 150 1.74E+01 0.0690 1.12E+01 0.0304 2.86E+01 0.0436 160 170 1.80E+01 0.0501 1.63E+01 0.0261 3.43E+01 0.0291 180 190 1.81E+01 0.0399 2.05E+01 0.0203 3.86E+01 0.0216 249.289 308.578 1.94E+01 0.0979 2.50E+01 0.0281 4.44E+01 0.0456 Average total 1.82E+01 0.0240 2.10E+01 0.0158 3.91E+01 0.0140 Average 90 2.20E+01 0.0172 3.68E+01 0.0167 5.88E+01 0.0123 Page 13 of 30
RAIs and Responses Enclosure 2 to E-62133 Table RAI 6.13-4 OS197FC Transfer Cask with 24PTH-L Type 3 DSC, Top Dose Rate, 1 -
Transfer Configuration Tally Neutron Total Gamma Total Midpoint Tally Outer (cm) Radii (cm) mRem/hr 1 error mRem/hr 1 error mRem/hr 1 error 15 30 3.99E+01 0.0051 3.82E+01 0.0049 7.81E+01 0.0035 40 50 3.40E+01 0.0043 3.88E+01 0.0045 7.28E+01 0.0031 60 70 2.66E+01 0.0041 3.62E+01 0.0072 6.28E+01 0.0045 77.5 85 1.97E+01 0.0046 4.07E+01 0.0157 6.04E+01 0.0107 86 87 1.70E+01 0.0106 7.73E+01 0.0480 9.43E+01 0.0394 88.5 90 1.61E+01 0.0102 5.47E+01 0.0379 7.08E+01 0.0294 100 110 1.44E+01 0.0045 2.26E+01 0.0146 3.70E+01 0.0091 120 130 1.54E+01 0.0042 1.06E+01 0.0108 2.61E+01 0.0050 140 150 1.70E+01 0.0039 1.09E+01 0.0046 2.79E+01 0.0030 160 170 1.74E+01 0.0042 1.48E+01 0.0027 3.22E+01 0.0026 180 190 1.76E+01 0.0043 1.91E+01 0.0021 3.66E+01 0.0023 249.289 308.578 1.78E+01 0.0060 2.19E+01 0.0026 3.97E+01 0.0031 Average total 1.87E+01 0.0025 2.13E+01 0.0074 4.00E+01 0.0041 Average 90 2.65E+01 0.0022 4.12E+01 0.0071 6.77E+01 0.0044 Page 14 of 30
RAIs and Responses Enclosure 2 to E-62133 Table RAI 6.13-5 OS197FC Transfer Cask with 24PTH-L Type 2 DSC, Top Dose Rate, Surface
- Decontamination Configuration Tally Neutron Total Gamma Total Midpoint Tally Outer (cm) Radii (cm) mRem/hr 1 error mRem/hr 1 error mRem/hr 1 error 15 30 3.14E-01 0.2858 6.39E+02 0.0331 6.40E+02 0.0331 40 50 2.05E-01 0.1154 7.83E+02 0.0272 7.83E+02 0.0272 60 70 2.40E-01 0.0975 6.72E+02 0.0244 6.72E+02 0.0244 77.5 85 3.14E-01 0.3567 4.29E+02 0.0266 4.29E+02 0.0266 86 87 1.63E-01 0.2651 4.19E+02 0.0725 4.19E+02 0.0725 88.5 90 1.94E-01 0.2160 2.44E+02 0.0497 2.44E+02 0.0497 100 110 6.35E-01 0.1051 6.40E+01 0.0308 6.47E+01 0.0305 120 130 2.31E+00 0.0528 9.39E+00 0.0449 1.17E+01 0.0375 140 150 5.25E+00 0.0329 9.08E+00 0.0299 1.43E+01 0.0224 160 170 8.69E+00 0.0237 1.27E+01 0.0162 2.14E+01 0.0136 180 190 1.27E+01 0.0198 1.68E+01 0.0137 2.95E+01 0.0116 249.289 308.578 2.30E+01 0.0071 2.42E+01 0.0087 4.72E+01 0.0057 Average total 1.63E+01 0.0067 7.03E+01 0.0162 8.66E+01 0.0132 Average 90 2.56E-01 0.1360 5.82E+02 0.0133 5.82E+02 0.0133 Page 15 of 30
RAIs and Responses Enclosure 2 to E-62133 Table RAI 6.13-6 OS197FC Transfer Cask with 24PTH-L Type 3 DSC, Top Dose Rate, Surface
- Decontamination Configuration Tally Neutron Total Gamma Total Midpoint Tally Outer (cm) Radii (cm) mRem/hr 1 error mRem/hr 1 error mRem/hr 1 error 15 30 3.39E-01 0.2249 8.93E+02 0.0040 8.93E+02 0.0040 40 50 2.77E-01 0.0547 9.90E+02 0.0033 9.91E+02 0.0033 60 70 2.69E-01 0.0561 8.06E+02 0.0030 8.06E+02 0.0030 77.5 85 2.59E-01 0.0502 4.88E+02 0.0033 4.88E+02 0.0033 86 87 3.72E-01 0.3110 4.06E+02 0.0127 4.07E+02 0.0127 88.5 90 3.59E-01 0.1955 2.75E+02 0.0058 2.76E+02 0.0058 100 110 5.45E-01 0.0317 7.89E+01 0.0043 7.95E+01 0.0043 120 130 1.78E+00 0.0143 1.13E+01 0.0110 1.30E+01 0.0097 140 150 4.13E+00 0.0072 8.22E+00 0.0094 1.24E+01 0.0067 160 170 6.83E+00 0.0049 1.07E+01 0.0066 1.75E+01 0.0045 180 190 9.67E+00 0.0040 1.39E+01 0.0035 2.36E+01 0.0026 249.289 308.578 1.80E+01 0.0012 1.93E+01 0.0015 3.73E+01 0.0010 Average total 1.27E+01 0.0011 7.85E+01 0.0021 9.12E+01 0.0018 Average 90 2.86E-01 0.0443 7.09E+02 0.0016 7.09E+02 0.0016 Page 16 of 30
RAIs and Responses Enclosure 2 to E-62133 Table RAI 6.13-7 OS197FC Transfer Cask with 24PTH-L Type 2 DSC, Top Dose Rate, Surface
- Welding Configuration Tally Neutron Total Gamma Total Midpoint Tally Outer (cm) Radii (cm) mRem/hr 1 error mRem/hr 1 error mRem/hr 1 error 15 30 3.37E+01 0.0658 6.55E+02 0.0359 6.88E+02 0.0343 40 50 2.81E+01 0.0479 8.56E+02 0.0264 8.84E+02 0.0256 60 70 2.22E+01 0.0341 7.49E+02 0.0394 7.71E+02 0.0383 77.5 85 2.19E+01 0.0429 5.59E+02 0.1125 5.81E+02 0.1083 86 87 2.21E+01 0.1482 8.39E+02 0.0757 8.62E+02 0.0739 88.5 90 2.12E+01 0.0742 5.24E+02 0.3356 5.45E+02 0.3226 100 110 9.23E+00 0.0566 7.89E+01 0.1132 8.81E+01 0.1015 120 130 7.90E+00 0.0613 1.67E+01 0.0506 2.46E+01 0.0396 140 150 8.93E+00 0.0431 2.13E+01 0.1802 3.03E+01 0.1276 160 170 1.03E+01 0.0354 2.61E+01 0.0303 3.64E+01 0.0239 180 190 1.26E+01 0.0303 3.40E+01 0.0453 4.66E+01 0.0341 249.289 308.578 1.82E+01 0.0135 4.15E+01 0.0101 5.97E+01 0.0082 Average total 1.63E+01 0.0120 9.46E+01 0.0474 1.11E+02 0.0405 Average 90 2.45E+01 0.0218 6.94E+02 0.0344 7.19E+02 0.0332 Page 17 of 30
RAIs and Responses Enclosure 2 to E-62133 Table RAI 6.13-8 OS197FC Transfer Cask with 24PTH-L Type 3 DSC, Top Dose Rate, Surface
- Welding Configuration Tally Neutron Total Gamma Total Midpoint Tally Outer (cm) Radii (cm) mRem/hr 1 error mRem/hr 1 error mRem/hr 1 error 15 30 4.15E+01 0.0036 9.37E+02 0.0037 9.78E+02 0.0035 40 50 3.42E+01 0.0033 1.06E+03 0.0028 1.10E+03 0.0027 60 70 2.88E+01 0.0031 8.58E+02 0.0025 8.87E+02 0.0024 77.5 85 2.83E+01 0.0031 5.71E+02 0.0033 5.99E+02 0.0031 86 87 3.09E+01 0.0076 7.81E+02 0.0191 8.12E+02 0.0184 88.5 90 2.68E+01 0.0069 3.86E+02 0.0080 4.12E+02 0.0075 100 110 1.13E+01 0.0035 8.57E+01 0.0034 9.70E+01 0.0031 120 130 9.01E+00 0.0046 1.91E+01 0.0066 2.81E+01 0.0047 140 150 9.11E+00 0.0042 1.79E+01 0.0051 2.70E+01 0.0037 160 170 1.01E+01 0.0041 2.36E+01 0.0036 3.37E+01 0.0028 180 190 1.17E+01 0.0041 2.90E+01 0.0027 4.06E+01 0.0023 249.289 308.578 1.62E+01 0.0022 3.51E+01 0.0012 5.13E+01 0.0011 Average total 1.57E+01 0.0021 9.84E+01 0.0017 1.14E+02 0.0015 Average 90 3.11E+01 0.0016 7.91E+02 0.0016 8.22E+02 0.0015 Page 18 of 30
RAIs and Responses Enclosure 2 to E-62133 Table RAI 6.13-9 Standardized Transfer Cask with 24PTH-S-LC Type 2 DSC, Top Dose Rate, Surface - Transfer Configuration Tally Neutron Total Gamma Total Midpoint Tally Outer (cm) Radii (cm) mRem/hr 1 error mRem/hr 1 error mRem/hr 1 error 15 30 8.03E+00 0.0778 1.14E+01 0.0648 1.94E+01 0.0498 40 50 6.95E+00 0.0667 1.13E+01 0.0507 1.83E+01 0.0404 60 70 5.68E+00 0.0443 9.25E+00 0.0474 1.49E+01 0.0338 77.5 85 4.02E+00 0.0785 9.99E+00 0.0457 1.40E+01 0.0396 86 87 2.43E+00 0.0754 3.01E+01 0.0894 3.25E+01 0.0829 88.5 90 2.62E+00 0.1619 1.76E+01 0.0646 2.02E+01 0.0600 100 110 5.14E+00 0.0687 7.07E+00 0.0516 1.22E+01 0.0416 120 130 5.96E+00 0.0429 2.27E+01 0.0525 2.86E+01 0.0425 140 150 5.45E+00 0.0356 3.07E+01 0.0393 3.61E+01 0.0338 160 170 5.01E+00 0.0342 3.29E+01 0.0296 3.79E+01 0.0261 180 190 5.28E+00 0.0704 3.48E+01 0.0251 4.00E+01 0.0237 249.289 308.578 5.83E+00 0.0175 3.53E+01 0.0205 4.11E+01 0.0178 Average total 5.65E+00 0.0152 3.10E+01 0.0205 3.66E+01 0.0175 Average 90 5.38E+00 0.0310 1.15E+01 0.0233 1.69E+01 0.0187 Page 19 of 30
RAIs and Responses Enclosure 2 to E-62133 Table RAI 6.13-10 Standardized Transfer Cask with 24PTH-S-LC Type 3 DSC, Top Dose Rate, Surface - Transfer Configuration Tally Neutron Total Gamma Total Midpoint Tally Outer (cm) Radii (cm) mRem/hr 1 error mRem/hr 1 error mRem/hr 1 error 15 30 8.35E+00 0.0081 1.55E+01 0.0122 2.39E+01 0.0084 40 50 7.33E+00 0.0066 1.44E+01 0.0085 2.17E+01 0.0061 60 70 5.82E+00 0.0058 1.06E+01 0.0075 1.64E+01 0.0052 77.5 85 4.04E+00 0.0059 1.18E+01 0.0108 1.59E+01 0.0082 86 87 3.03E+00 0.0123 2.92E+01 0.0280 3.23E+01 0.0254 88.5 90 2.57E+00 0.0130 1.85E+01 0.0178 2.10E+01 0.0157 100 110 4.44E+00 0.0049 8.17E+00 0.0070 1.26E+01 0.0048 120 130 6.03E+00 0.0047 2.82E+01 0.0060 3.43E+01 0.0050 140 150 5.28E+00 0.0051 3.71E+01 0.0053 4.23E+01 0.0047 160 170 4.76E+00 0.0054 3.50E+01 0.0040 3.98E+01 0.0036 180 190 4.71E+00 0.0056 3.39E+01 0.0034 3.86E+01 0.0031 249.289 308.578 4.98E+00 0.0031 3.08E+01 0.0022 3.58E+01 0.0020 Average total 5.04E+00 0.0030 2.91E+01 0.0022 3.42E+01 0.0020 Average 90 5.56E+00 0.0031 1.36E+01 0.0050 1.91E+01 0.0037 Page 20 of 30
RAIs and Responses Enclosure 2 to E-62133 Figure RAI 6.13-1 OS197FC Transfer Cask with 24PTH-L Type 2 DSC, Top Dose Rate, Surface
- Transfer Configuration Page 21 of 30
RAIs and Responses Enclosure 2 to E-62133 Figure RAI 6.13-2 OS197FC Transfer Cask with 24PTH-L Type 3 DSC, Top Dose Rate, Surface
- Transfer Configuration Page 22 of 30
RAIs and Responses Enclosure 2 to E-62133 Figure RAI 6.13-3 OS197FC Transfer Cask with 24PTH-L Type 2 DSC, Top Dose Rate, Surface
- Decontamination Configuration Page 23 of 30
RAIs and Responses Enclosure 2 to E-62133 Figure RAI 6.13-4 OS197FC Transfer Cask with 24PTH-L Type 3 DSC, Top Dose Rate, Surface
- Decontamination Configuration Page 24 of 30
RAIs and Responses Enclosure 2 to E-62133 Figure RAI 6.13-5 OS197FC Transfer Cask with 24PTH-L Type 2 DSC, Top Dose Rate, Surface
- Welding Configuration Page 25 of 30
RAIs and Responses Enclosure 2 to E-62133 Figure RAI 6.13-6 OS197FC Transfer Cask with 24PTH-L Type 3 DSC, Top Dose Rate, Surface
- Welding Configuration Page 26 of 30
RAIs and Responses Enclosure 2 to E-62133 Figure RAI 6.13-7 Standardized Transfer Cask with 24PTH-S-LC Type 2 DSC, Top Dose Rate, Surface - Transfer Configuration Page 27 of 30
RAIs and Responses Enclosure 2 to E-62133 Figure RAI 6.13-8 Standardized Transfer Cask with 24PTH-S-LC Type 3 DSC, Top Dose Rate, Surface - Transfer Configuration Page 28 of 30
RAIs and Responses Enclosure 2 to E-62133 RAI 6.14:
Explain how the additional allowed weight for the fuel assemblies and control components in the Type 3 basket will or will not affect the radiation source terms, including total source terms and axial distribution of source terms and modify the shielding analysis as necessary.
Since the Type 3 basket weighs less than the currently approved basket types in the 24PTH DSC, the applicant has proposed increasing the allowed weight of the fuel assembly and control component contents in each basket cell. The increase is about 15 kilograms. With an increase in mass comes an increase in source term as well. It is not clear how this increase in source term from increased allowed mass has been considered in the shielding analyses. The maximum mass of uranium per fuel assembly remains fixed. So, the increased mass would be in control components or assembly hardware, which increases the cobalt-60 source due to activation of these items. While increased mass does increase self-shielding, the staffs simple calculations indicate that the increased self-shielding is not sufficient to compensate for the increase in source term (i.e., dose rates will increase). Additionally, the distribution of the added weight and added source term can have a significant impact on dose rates. If the added mass is in either the upper or lower hardware zones of the assemblies, the respective axial dose rates for the DSC will increase, potentially significantly.
This information is needed to confirm compliance with 10 CFR 72.236(b) and (d).
Original Response to RAI 6.14:
Change no. 1 in Enclosure 2 of submittal E-60447, which relates to the increase of the NUHOMS-24PTH Dry Shielded Canister (DSC) weight limit from 1682 lb to 1715 lb for fuel assembly plus control component (CC) based on the lighter Type 3 basket, does not allow loading of higher overall source in a Type 3 DSC. The maximum initial uranium content is still limited to 492 kg per assembly as indicated in CoC 1004 Appendix B Amendment 18 Technical Specifications (TS) Table 1-1I, and the maximum CC source per DSC is limited to values shown in CoC 1004 Appendix B Amendment 18 TS Table 1-1n.
For loading fuel assemblies in a NUHOMS-24PTH Type 3 DSC, the licensee is expected to demonstrate, among other requirements in CoC 1004 Appendix B Amendment 18 TS Table 1-1I, that the maximum initial uranium content is less than 492 kg per assembly, the fuel assembly weight with CC is less than 1715 lb, and the total CC source per DSC is lower than the values shown in CoC 1004 Appendix B Amendment 18 TS Table 1-1n.
Original Impact:
No change as a result of this RAI.
Supplemental Response to RAI 6.14:
The increase of the NUHOMS-24PTH Dry Shielded Canister (DSC) weight limit from 1,682 lb to 1,715 lb is the result of using the most conservative fuel assembly weight with the most conservative control component weight as well as the uncertainties in those weights. In addition, the increased allowable weight for each basket cell within the Type 3 basket would not lead to changes in the axial distribution of the fuel assembly and control components radiation source terms in the basket cell.
Page 29 of 30
RAIs and Responses Enclosure 2 to E-62133 Supplemental Impact:
No change as a result of this RAI.
Page 30 of 30
Enclosure 3 to E-62133 DESCRIPTION OF AMENDMENT 18 CHANGES NOT RELATED TO RAIs INTRODUCTION In addition to the supplemental RAI responses provided as part of Amendment 18, Revision 5, the following non-RAI supplemental change has been provided as described below.
Change No. 1:
A change has been included to provide more specificity as to the criteria that determines when HSM concrete temperature testing is performed based on earlier discussions with NRC.
In support of this additional change, a revision has been made to CoC Appendix A, Inspections, Tests, and Evaluations, Section 4.2.
Page 1 of 1