ML25142A334
| ML25142A334 | |
| Person / Time | |
|---|---|
| Site: | 07201052 |
| Issue date: | 05/22/2025 |
| From: | Gesellschaft fur Nuklear-Service mbH |
| To: | Shana Helton Division of Fuel Management |
| References | |
| EPID L-2021-NEW-0006, CAC 001028 | |
| Download: ML25142A334 (1) | |
Text
Enclosure 3 to T1213-CO-00026 1
Response on Requests for additional information dated February, 18th and 25th, 2025, March, 4th, March 11th 2025 and April 15th Model No. CASTOR geo69 Docket-No.: 72-1052, EPID No. L-2021-NEW-0006 Non-Proprietary Version OPERATIONS (Op)
- 1. RAI dated February, 18th 2025 1-1 In response to RAI OP-3, the applicant revised Tables 9.1-1, 9.1-2, 9.2-2, 9.3-1, and 9.3-2 to include acceptance criteria requirements for leak testing.
Specifically, these tables include the leak testing timing requirements to be 105 hours0.00122 days <br />0.0292 hours <br />1.736111e-4 weeks <br />3.99525e-5 months <br />.
Sections in Chapter 4, Section 9.1.2 of Chapter 9 specify that the maximum permissible time periods after dewatering the canister until completion of inertization must not exceed 105 hours0.00122 days <br />0.0292 hours <br />1.736111e-4 weeks <br />3.99525e-5 months <br /> However the applicant revised LCO 3.1.2 (Appendix 13-1 to 1014-SR-00002) to specify the maximum drying criteria to hours Please update the SAR chapters to be consistent with the changes made to LCO 3.1.2,or provide technical justification for specifying h in Chapter 4 and Chapter 9 of the SAR.
Answer:
The initial question/comment by NRC (E-Mail dated January 14th 2025 Question
- 1) concerning LCO 3.1.2 in the technical specification (1014-TR-00077 Rev. 1) was to quantify the amount of cooldown prior to resuming vacuum drying because if the user restarts vacuum drying at a higher temperature than the analysis temperature (i.e., the system has not adequately cooled down) and requires hours to reach vacuum drying criterion (or once again fails to achieve the criterion), the basket material allowable temperature may be exceeded.
In order to rule out this topic, we split the limit, which is justified in SAR Section 4.7.4, into three intervals. This is possible since we know from decades of experience that typically the dryness criterion will be reached after a much shorter drying time (e.g.
). This is condition A of LCO 3.1.2 If, contrary to expectations, the criterion cannot be achieved after it is possible to continue drying. We have defined two further time intervals for this purpose: Condition B of LCO 3.1.2 with and condition C with If the criterion has still not been met after these there is obviously a complication that requires further investigation. A further are then available to backfill the canister cavity with helium and initiate measures to return the canister to a safe condition or to return it into the SNF pool.
Thus, there is no contradiction between LCO 3.1.2 and the 105 h mentioned in the SAR, which are justified in section 4.7.2.
Steps 1.2.10 and 2.2.8 in Table 9.1-2 have been clarified in Rev. 3 of the SAR to reflect these circumstances and an explanation has been added above Table 9.1-2.
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1-2 In response to RAI OP-3, the applicant revised Tables 9.1-1, 9.1-2, 9.2-1, 9.2-2, 9.3-1and 9.3-2, however, there are several steps where the applicant did not include either acceptance criteria or precautionary requirements.
Further, the applicant did not expand several steps such as steps 2.5, 2.6 in Table 9.1-1. In Table 9.1-2, steps 2.1, 2.3, 2.4, 4.1, 4.2, 4.3 and step 5; Table 9.2-1, step 2.3; Table 9.2-2, step 2.2; Table 9.3-1 steps 1.1, 1.2, and step 5; Table 9.3-2 step 1.1 and step 3.
Please provide operational procedural acceptance criteria or precautionary requirements for each steps as well as expand the operational steps in Table 9.1-1 through Table 9.3-2 specified above.
Answer:
All tables in chapter 9 have been checked for missing operational procedural acceptance criteria or precautionary requirements for visual inspections or checks and supplemented accordingly where applicable.
Requirements should now have been added for all steps where this makes sense.
Table 9.1-1: - Steps 2.5, 2.6 expanded Table 9.1-2: - Steps 2.1, 2.3 not expanded but reference added to Section 11.1. Temporary shielding material is in the responsibility of the user.
- Step 2.4 expanded
- Steps 4.1, 4.2, 4.3 adjusted
- Step 5 expanded by 1 sub step. For the subsequent steps see Section 9.3.2 Table 9.2 Step 1.1 adjusted
- Step 2.3 is already expanded
- Step 3.3 expansion not applicable, requirement added Table 9.2 Step 2.2 expansion not applicable, requirement added Table 9.3 Steps 1.1, 1.2 expansion not applicable, requirement added
- Step 1.4 adjusted
- Step 5 deleted, not a work step.
Table 9.3 Step 1.1: expansion not applicable, requirement added
- Step 3: deleted, not a work step 1-3 In response to RAI OP-4, the applicant revised tables 9.1-2 and 9.3-1 specifying the values of nominal torque in Requirement, column, stating these are consistent with Chapter 3.
Upon comparison with the torque values specified in the response against those specified in Chapter 3 tables, the staff found the torque values specified did not match.
For example:
Table 3.1-4 specify pre-load torque of Table 3.1-2 specify pre-load torque of Table 3.1-5 specifies the pre-load torque of Table 3.11-11 specify tightening torque tolerance of nominal tightening torque of and Max chosen tightening torque of to T1213-CO-00026 3
Table 3.11-7 specify nominal preload (definition) input of with preload tolerance during ultrasonic controlled tightening of Please revise the units.
Please specify which Tables in Chapter 3 specify the following torque values that were provided in response to the RAI:
- 1.
- a. Step 2.2.2 -
- b. Step 2.2.7 -
- c. Step 2.2.11 -
- d. Step 3.3.10 -
- e. Step 4.42 -
Answer:
For clarification, the following Table summarizes the tightening torques for the various screw connections, the work steps in Table 9.1.2 and the specification in chapter 3:
Step of Tab. 9.1-2 Screw connection Tightening torque/
preload force Specification 2.2.2 Thread bolts for canister lid closure Chapter 3, Appendix 3-2, Tab. 3.11-5 2.2.7 Quick connect GNS Experience 2.2.11 Pressure nut Chapter 3, Appendix 3-2, Tab. 3.11-11 3.3.2 Screws for pressure switch Chapter 3, Appendix 3-2, Tab. 3.11-8 3.3.10 Screws for cask lid Chapter 3, Appendix 3-2, Tab. 3.11-7 3.3.15 Screws for protection cap Chapter 3, Appendix 3-2, Tab. 3.11-9 4.3.2 Sealing screw with valve GNS Experience The unit kN in steps 2.2.2 and 3.3.10 (
) are correct, since it is not a tightening torque but a preload force applied during ultrasonic controlled tightening.
The value in step 2.2.2 has been changed from (tightening torque) to (preload force).
The tightening torques in steps 2.2.7 and 4.3.2 are bases on GNS experience with components of this type usually utilized. They will be purchased commercially by different manufactures, who typically specify these tightening torques. A verification within the structural evaluations is not applicable, as the components are not part of the containment and not important to safety.
Section 3.1.3 of the SAR is only a comparison between German and US standards and therefore only repeats tightening torques that are defined elsewhere in the SAR.
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1-4 In Technical Specification Basis: Technical Report 1014-TR-00077, Revision 1, the applicant left the Completion Time requirements blank. Please provide the completion time required for each LCOs.
The COMPLETION TIMES for many of the REQUIRED ACTIONS in the following LCOs often are blank or are written as As soon as possible (i.e.,
vague and open-ended).
LCO 3.1.3, REQUIRED ACTION A.2; LCO 3.1.4, REQUIRED ACTION A.1, REQUIRED ACTION B.1/B.2, AND REQUIRED ACTION C.1; LCO 3.1.5, REQUIRED ACTION A; LCO 3.1.6, REQUIRED ACTION A.2 (note, the COMPLETION TIME for REQUIRED ACTION A.1 would appear to be Immediately, as noted for LCO 3.1.3; LCO 3.1.8, REQUIRED ACTION A.1, REQUIRED ACTION B.1/B.2, REQUIRED ACTION C.1; LCO 3.2.1, REQUIRED ACTION A.1, REQUIRED ACTION B.1/B.2; LCO 3.2.2, REQUIRED ACTION A.1, REQUIRED ACTION D.1/E.1/
Answer:
The Technical Specification Basis 1014-TR-00077 (Appendix 13-1 to the SAR) was updated as follows:
LCO 3.1.2: Complete revision considering time limits.
LCO 3.1.3: Time limits added.
LCO 3.1.4: Complete revision considering time limits.
LCO 3.1.5: Time limits added.
LCO 3.1.6: Time limits added.
LCO 3.1.7: Change in some time limits.
LCO 3.1.8: Complete revision considering time limits.
LCO 3.2.1: Time limits added.
LCO 3.2.2: Time limits added.
1-5 In response to RAI, the applicant revised Section 9.1.2 Loading of Contents by specifying the proof is considered to be provided if the pressure criterion can be kept stable for at least However, in Technical Specification, LCO -3.1.2 and LCO-3.1.5 specify vacuum drying pressure rise to be sustained for a period for at least Provide updated LCO to specify consistent vacuum drying pressure and time requirements.
Answer:
This comment is correct. The dryness criterion is and has been corrected in the Technical Specification Basis 1014-TR-00077 (Appendix 13-1 to the SAR) and in Table 9.1.2 of the SAR.
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- 2. RAI dated February, 25th 2025 2-1 CASTOR geo69 Part 72 LCO 3.1.2 (see attachment from email below) includes a canister backfill pressure of in the event that vacuum drying criteria cannot be met. Note that the normal condition canister pressure is approximately (SAR section 7.2) and the impact accident canister pressure is (SAR section 7.4.3). The staff noticed that the response to RAI-St-4 also listed a maximum canister pressure of The staff wants to confirm that the LCOs helium backfill pressure in the canister is OK or whether it should be a lower number.
Answer:
The pressure values, applied in the structural evaluations are listed in Table 3.11-6 of Appendix 3-1 of the SAR. From this Table it can be seen, that the maximum assessed internal canister overpressure is for the test load case. Thus, a canister backfill pressure of is OK. However, to be consistent with the maximum internal canister overpressure for NCS and ACS, the helium backfill pressure in LCO 3.1.2 has been reduced to 2-2 Please propose quantifiable COMPLETION TIMEs (and its rationale) for the LCOs Required Actions listed below (for example, previous feedback was that COMPLETION TIMES of As soon as possible are open-ended). The following are examples of LCOs that need a quantifiable completion times:
LCO 3.1.2, REQUIRED ACTION B.2; LCO 3.1.3, REQUIRED ACTION A.2; LCO 3.1.4, REQUIRED ACTION A.1, REQUIRED ACTION B.1/B.2, AND REQUIRED ACTION C.1; LCO 3.1.5, REQUIRED ACTION A; LCO 3.1.6, REQUIRED ACTION A.2 (note, the COMPLETION TIME for REQUIRED ACTION A.1 would appear to be Immediately, as noted for LCO 3.1.3);
LCO 3.1.8, REQUIRED ACTION A.1, REQUIRED ACTION B.1/B.2, REQUIRED ACTION C.1; LCO 3.2.1, REQUIRED ACTION A.1, REQUIRED ACTION B.1/B.2; LCO 3.2.2, REQUIRED ACTION A.1, REQUIRED ACTION D.1/E.1 (also, address As soon as possible)
Please verify that all proposed TSs include quantifiable completion times.
Answer:
See comment/answer to point 1-4 to T1213-CO-00026 6
- 3. RAI dated March, 4th 2025 3-1 DSS (LCO 3.2.3 and LCO 3.2.6). Neither LCO 3.2.3 nor LCO 3.2.6 appears in SAR Chapter 13. Further Tech Spec Administrative Controls 4.1.1.2 mentions LCO 3.2.7. LCO 3.2.7 does not appear in SAR Chapter 13.
Answer:
In Rev. 2 of the technical specifications the references LCO 3.2.3, LCO 3.2.6 and LCO 3.2.7 in Section 5.1.1 have been corrected to LCO 3.1.3, LCO 3.1.6 and LCO 3.2.1.
3-2 A canister fabrication helium leak test (i.e., including the base metal and welds) is not explicitly described anywhere in the CASTOR geo69 Tech Specs; why has a description and details of the fabrication leak test been excluded?
Answer:
Chapter 13 of the SAR and thus also the technical specifications discuss relevant aspects to be controlled during cask operations. The technical specifications base on requirements of NUREG-1745.
All acceptance tests (including helium leak tests) will be performed during manufacturing in accordance with the requirements of Chapter 10 of the SAR.
During cask operations there is no need for any further fabrication control of welds, as the canister will be closed by a screwed lid and not welded in field.
3-3 The canister LCO 3.1.4 and cask LCO 3.1.8 for leakage testing focused only on the closure system on loading. It is not clear what specifically defines the closure system for measuring the combined helium leakage rate---whether it is the large lid closure or does it also include the port plug gasket closure, pressure switch gasket closure, etc. Clarification of what defines the closure system is requested.
Answer:
LCO 3.1.4 and LCO 3.1.8 have been completely revised to discuss exactly the topic addressed by NRC (See item 1-4 of this response). The combined standard helium leakage rate for the closure system means, that all seals of a lid closure system (cask together with protection cap and blind flange/pressure switch on the one hand and canister together with the tightening plug on the other hand) shall fulfil the leakage criterion.
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- 4. RAI dated March, 11th 2025 Shielding (Sh) 4-1 Clarify what is the minimum cooling times (in years) needed to reach certain decay heat for the fuel assembly In Table 5.2-2 of the SAR, the applicant described that for the fuel assembly, the minimum cooling times (in years) needed to reach certain decay heat as years. However, in section 2 (Approved Content) of the document 1014-SR-00002, the applicant states that the minimum cooling times (in days) is The staff is no clear which minimum cooling times is needed to reach decay heat for the fuel assembly The staff observed that the applicant used for the source terms calculations.
This information is needed to determine compliance with 10 CFR 71.47 and 71.51.
Answer:
In fact, there is no discrepancy here. Both numbers are correct, but the intention of the tables is different:
The minimum decay time of years for the fuel assembly listed in Chapter 5, Table 5.2-2 was determined for a maximum burn-up of plus burn-up uncertainty).
The minimum decay time of listed in Table 2.1-1 of the SAR and in the table in Chapter 2 of the technical specification (1014-TR-00077) applies in principle to fuel assemblies regardless of how low the burn-up is. The higher the burn-up, the longer is the minimum cooling time.
Thus, no changes to the SAR or technical specification are necessary.
OPERATIONS (Op) 4-2 The applicant should clarify the criterion in LCO 3.1.2 and LCO 3.1.5 and the units.
The applicants Response to RAI document explains that the dryness criterion is (as written in the revised Chapter 9, section 9.1.2),
thereby changing their LCOs prior use of However, their LCO is written as the pressure rise shall be sustained Based on the RAI response, it would appear the language was meant to be written as the pressure shall be sustained for a period of at least Likewise, SAR table 9.1-2 step 2.2.6 and 3.3.12 would then change the Requirement to pressure rather than using the symbol p. In brief, the applicant should clarify their criterion (pressure vs.
pressure rise) and the units (i.e., whether the criterion is meant to be to T1213-CO-00026 8
Answer:
We apologize for this inconsistency. The explanation in Section 9.1.2 is correct, the criterion is
. LCO 3.1.2 and LCO 3.1.5 and SAR Table 9.1-2 step 2.2.6 and 3.3.12 have been adjusted accordingly in the SAR.
4-3 Per earlier emails, it was mentioned that a drawing note should mention the storage cask outer surface coating and transfer cask outer surface coating is to have a minimum emissivity coefficient value of 0.93. However, if that is not possible for the applicant, then a Tech Spec Design Specification can include a similar sentence.
Answer:
GNS prefers not to update the Drawings. An implementation in the Design Tech Spec is sufficient from our side.
Point 1 of the listing in Section 3.1.2 Materials of the TechSpec Basis (1014-TR-00077) has been supplemented with the following requirement:
, the outer coating shall provide an emissivity coefficient value of at least 0.93, the inner coating of al least 0.6 4-4 You will be able to cut-and-paste the SAR figure 4.1-1 loading diagrams (or generate new figures) in the Tech Specs Approved Contents section (which item D currently just refers to SAR Chapter 4.1.2).
Answer:
The loading diagrams have been added to the TechSpec Basis (1014-TR-00077).
4-5 During your weekly call with the applicant, please have the applicant confirm that the VMQ elastomeric seal material is vinyl methyl silicone and the FKM elastomeric seal material is fluorocarbon rubber. [Note that these two materials were not spelled out.]
Answer:
Yes, these are the correct definitions. Both abbreviations will be added to the Glossary in Chapter 0 of the SAR in the final revision.
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- 5. RAI dated April, 15th 2025 OPERATIONS (Op) 5-1 Provide the rationale and basis for the water flow rates mentioned in section 9.2.1 of the SAR. Also, confirm that these flow rates would not result in steam generation that may adversely affect the allowable pressure inside of the storage system.
Regarding the applicants discussion in SAR section 9.2.1 about recooling of SNF (i.e., reflooding), it mentions that the procedure is according to written and approved procedures to protect the loaded FAs from damage due to thermal shock. The applicant should also indicate that the water reflood rate (i.e.,
and connections to the canister prevent excessive pressures within the canister during the reflood process (e.g., steam generation is not excessive such that the canister would be pressurized beyond normal condition allowable pressures). [Note that the steam/recooling process should address the presence radioactive contaminants of the fuel (e.g., crud).]
Revise the SAR section 9.2.1 to reflect this information.
Answer:
The water flow rates (of about
) are recommendations based on decades of experience with re-cooling of CASTOR casks. As mentioned in Section 9.2.1, bullet point 6, t Corresponding changes to Section 9.2.1 have been implemented the SAR.
5-2 Please revise the reference to NUREG-2215 in Chapter 9.1 After a sufficient drying period, the interior is disconnected from the vacuum pump and the maximum permissible residual moisture has to be verified. The proof is considered to be provided if the pressure criterion can be kept stable for at least In accordance with NUREG-2215 [4] (Section 8.5.15.2.3, examples of accepted methods for drying), the amount of residual water is constrained to only a few grams as shown by [5].
The correct section of NUREG-2215 that provides examples method of drying is 11.5.2.6, Draining and Drying. Also ensure that the references to NRC documents are accurate throughout the application.
Answer:
This mistake has already been noticed, and the reference has been corrected in the final submission of the SAR.