ML18242A086
| ML18242A086 | |
| Person / Time | |
|---|---|
| Site: | 07109373 |
| Issue date: | 07/31/2018 |
| From: | Holtec |
| To: | Office of Nuclear Material Safety and Safeguards |
| References | |
| 5024010, LAR-9373-1 | |
| Download: ML18242A086 (7) | |
Text
NRC RAI 2-1 Revise the drawing list by adding Drawing 11107, Sheets 1-2, Rev. 0, for the enhanced Damaged Fuel Canister (DFC) design, to CoC Condition 5(a)(3), Drawings, as included in enclosure 2 to Holtec Letter 5024009, to the CoC.
The staff needs this information to determine compliance with 10 CFR 71.33(b)(1).
Holtecs Response to RAI 2-1 The drawing list in CoC Condition 5(a)(3) has been revised to include DFC Drawing 11107, Sheets 1-2, Rev. 1. Revision 1 includes options that enable loading of smaller sizes of fuel assemblies. Complete list of changes for Revision 1 of Drawing 11107 along with the revised drawing are in Enclosure 3 to Holtec Letter 5024010.
to Holtec Letter 5024010 Page 1 of 7
NRC RAI 2-2 Revise the application to ascertain that the structural evaluations, as discussed In Enclosure 1 to Holtec Letter 5024009, "Summary of Proposed Changes (SOPC) for LAR 9373-1," are properly presented in the application.
While there are numerous instances where the applicant makes statements related to the structural adequacy of the proposed changes, there is no justification or indication that the subject structural adequacy discussion has been properly evaluated in the application. The following sentences are highlighted as examples:
i) Proposed Change #1 : "This proposed change is bounded by the design basis thermal, structural and shielding analyses for the HI-STAR 190 system; therefore no additional analyses are required."
ii) Proposed Change# 2: "Assemblies modified by the addition of GTAs, and meeting the dimensional and weight acceptance criteria in the Appendix 7.C of the SAR, including assembly weight and overall length are acceptable for transport in the HISTAR 190 package, with no further structural evaluation."
iii) Proposed Change #3: "The temperatures and pressures in the HI-STAR 190 for heat load Pattern 7 are bounded by the design basis (Pattern 1). There is no effect on the currently approved structural analysis."
iv) Proposed Change #4: "The proposed change has no impact on the structural, confinement and criticality evaluations."
v) Proposed Change #5: "The proposed change has no impact on the structural and criticality evaluations."
vi) Proposed Change #6: "Design basis Shielding, Thermal and Structural analyses bound this proposed change, and therefore no additional analysis is required."
All such statements shall be clearly explained and justified. References to previous "bounding" analyses and applicable statements demonstrating that such analyses are "bounded" shall be documented.
The staff needs this information to determine compliance with 10 CFR 71.31 (a)(2) and 71.35(a).
Holtecs Response to RAI 2-2 The Summary of Proposed Changes (SOPC) for LAR 9373-1 has been revised to provide clarifications and justifications that support statements made regarding impact of certain to Holtec Letter 5024010 Page 2 of 7
proposed changes on structural, thermal, shielding, criticality or containment evaluations. Where appropriate, sections of the SAR have been updated.
to Holtec Letter 5024010 Page 3 of 7
NRC RAI 5-1 Clarify "Option 1" in Note 7 for Table 7.C.8(b) of the application Table 7.C.8(b) of the application has minimum enrichment, minimum cooling time and maximum burn up requirements for 16x16A, B and C fuel assembly classes. Most nonfuel hardware (NFH) in the HI-STAR 190 is loaded according to the minimum cooling time and maximum burnup requirements in Table 7.C.13 of the application; however, Note 7 to Table 7.C.8(b) of the application has some exceptions to Table 7.C.13 of the application. Specifically, Option 1 to Note 7 to Table 7.C.8(b) allows NFH as specified in Table 7.C.13 of the application with the exception of thimble plug devices (TPDs), which are not allowed and burnable poison rod assemblies (BPRAs) require a minimum cooling time of 25 years. This note states: TPD is not allowed and minimum cooling time of BPRAs is 25 years, independent of fuel cooling time.
The requirements for other NFH devices are in Table 7.C.13." The staff has found that there are other NFH that are represented using the models for the TPD and the BPRA and that there cannot be restrictions to only TPD and BPRA loading without having restrictions on this other NFH unless additional evaluations are performed.
In Table 7.C.13 of the application, TPD burnup and cooling time loading limits are included in the column "NSA or Guide Tube Hardware." Per Note 5 to Table 7.C.13 of the application, water displacement guide tube plugs and orifice rod assemblies are also loaded using the burnup and cooling time combinations from the "NSA or Guide Tube Hardware" column and as stated in Section 5.2.3.1 of the application are analytically treated the same within the dose rate evaluations in Chapter 5 of the application.
Clarify if water displacement guide tube plugs and orifice rod assemblies are allowed with 16x16A, B and C fuel assembly classes loaded under Table 7.C.8(b) of the application and, if so, provide the analysis information justifying their inclusion. Otherwise the staff requests Option 1 to Note 7 of Table 7.C.8(b) of the application to be modified to be consistent with the language in Table 7.C.13 of the application and state that water displacement guide tube plugs, and orifice rod assemblies are also not allowed.
Similar to TPDs, in Table7.C.13 of the application, BPRA burnup and cooling time loading limits are included in the column "Inserts." Per Note 4 to Table 7.C.13 of the application, this also includes Wet Annular Burnable Absorbers (WABAs), vibration suppressor inserts and TPDs with absorber rodlets. As stated in Section 5.2.3.1 of the application these are analytically treated the same within the dose rate evaluations in Chapter 5 of the application.
Clarify if WABAs, vibration suppressor inserts and TPDs with absorber rodlets will retain cooling time and burnup requirements from Table 7.C.13 of the application when transported with 16x16A, B and C fuel assembly classes loaded under Table 7.C.8(b) of the application and, if so, provide the analysis information justifying their inclusion. Otherwise the staff requests to Holtec Letter 5024010 Page 4 of 7
Option 1 to Note 7 of Table 7.C.8(b) of the application to be modified to be consistent with the language in Table 7.C.13 of the application and state that WABAs, vibration suppressor inserts and TPDs with absorber rodlets also require a minimum cooling time of 25 years.
The staff needs this information to determine compliance with 10 CFR 71.47 and 10 CFR 71.51 (a)(2).
Holtecs Response to RAI 5-1 Option 1 to Note 7 to Table 7.C.8(b) is updated as requested by the NRC.
to Holtec Letter 5024010 Page 5 of 7
NRC RAI 5-2 Justify that the burnup assumed for the neutron source assemblies (NSA) and axial power shaping rods (APSR) non-fuel hardware components is bounding or add the appropriate burnup limit to Option 2 and 3 to Note 7 of Table 7.C.8(b) of the application.
Proposed Option 2 and 3 to Note 7 of Table 7.C.8(b) of the application allows APSRs, control components and one NSA with a minimum cooling time of 7 years with no maximum burnup requirement.
The applicant incorporated the source term from these components into the dose rate evaluations.
This is discussed in Appendix I to HI-2167524 Revision 1, "HI-STAR 190 Source Terms and Loading Patterns Using SCALE 6.2.1," (ADAMS Accession No. ML18030A804). This document states that the NSA source term was calculated using a burnup of 360,000 MWD/MTU, with a further statement that: "The maximum burnup of 360,000 MWD/MTU is conservative since studies with various non-fuel hardware show that Co-60 activity decreases from 360000 MWD/MTU to 630000 MWD/MTU, due to cobalt depletion."
For APSRs (which the applicant also uses to represent control components) the applicant states:
"The Inconel and steel Co-60 activities for APSRs are calculated assuming bounding burnup (in the range of 40,000 MWD/MTU to 360,000 MWD/MTU)." The value in Table I.3 for Curies of Co-60/kg for ASPRs corresponds to that from page 31-22 of HI-951322 Revision 24, "HI-STAR 100 Shielding Design and Analysis for Transport and Storage," for 7 years cooling time and "max" burnup.
The staff requests the following additional information with respect to the maximum burnup for these hardware components:
a) Justify that 630,000 MWD/MTU is the maximum possible burnup experienced by an NSA and provide references to the studies with various non-fuel hardware that show that Co-60 activity is at its maximum when NFH is activated with fuel burned to 360,000 MWD/MTU, as compared to NFH activated with fuel burned to a higher burn up level up to 630,000 MWD/MTU due to cobalt depletion, or add the limit of 360,000 MWD/MTU to Options 2 and 3 to Note 7 of Table 7.C.8(b) of the application.
b) For APSR activation, clarify what the value of "max" burnup is on Page 31-22 of HI-951322 Revision 24 and justify that this is the maximum possible burnup experienced by an APSR and control components or add this burnup limit to Option 2 and 3 to Note 7 of Table 7.C.8(b) of the application.
The staff needs this information to determine compliance with 10 CFR 71.47 and 10 CFR 71.51(a)(2). to Holtec Letter 5024010 Page 6 of 7
Holtecs Response to RAI 5-2 a) Additional source term analysis for NSA up to burnup of 630,000 MWD/MTU is performed and documented in Appendix 39 of HI-951322 R25. It is shown the Co-60 activity decreases as the burnup increases from 360,000 MWD/MTU to 630,000 MWD/MTU. The limit of 630,000 MWD/MTU for NSAs is added to Option 2 to Note 7 of Table 7.C.8(b) of the application.
b) Additional source term analysis for APSRs up to burn up of 630,000 MWD/MTU is performed and documented in Appendix 31 of HI-951322 R25. It is shown that the APSR Co-60 activity decreases as the burnup increases from 360,000 MWD/MTU to 630,000 MWD/MTU. The limit of 630,000 MWD/MTU for APSRs and control components is added to Option 2 and Option 3 to Note 7 of Table 7.C.8(b) of the application.
It should be noted that the column max on Page 31-22 of HI-951322 Revision 25 (and Revision 24) provides the maximum cobalt-60 activity for the evaluated burnup values, for each cooling time. For example, for the cooling time of 7 years, the maximum cobalt-60 activity of Inconel is 646 curies/kg Inconel, which corresponds to the burnup of 180,000 NWD/MTU. In fact, based on the values provided in Page 31-22 of HI-951322 Revision 25 the activity of Inconel is maximum when the burnup is 180,000 MWD/MTU. The cobalt-60 activity remains almost unchanged between burnups values of 180,000 MWD/MTU and 225,000 MWD/MTU and decreases for burnups more than 225,000 MWD/MTU.
to Holtec Letter 5024010 Page 7 of 7