ML18360A186
| ML18360A186 | |
| Person / Time | |
|---|---|
| Site: | 07200020 |
| Issue date: | 12/21/2018 |
| From: | Kristina Banovac Renewals and Materials Branch |
| To: | Michael Layton Division of Spent Fuel Management |
| References | |
| CAC 000993, CAC 001028, EPID L-2017-LNE-0007, EPID L-2017-RNW-0019 | |
| Download: ML18360A186 (8) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 December 21, 2018 MEMORANDUM TO: Michael C. Layton, Director Division of Spent Fuel Management Office of Nuclear Material Safety and Safeguards FROM:
Kristina L. Banovac, Project Manager
/RA/
Renewals and Materials Branch Division of Spent Fuel Management Office of Nuclear Material Safety and Safeguards
SUBJECT:
SUMMARY
OF DECEMBER 6, 2018, MEETING WITH U.S.
DEPARTMENT OF ENERGY TO CLARIFY THE RESPONSES TO THE REQUEST FOR ADDITIONAL INFORMATION REGARDING THE RENEWAL OF THE THREE MILE ISLAND UNIT 2 INDEPENDENT SPENT FUEL STORAGE INSTALLATION LICENSE (SNM-2508)
(CAC/EPID NOS. 001028/L-2017-RNW-0019 AND 000993/L-2017-LNE-0007)
=
Background===
On December 6, 2018, a meeting was held between representatives of the U.S. Department of Energy (DOE) and the U.S. Nuclear Regulatory Commission (NRC) to clarify DOEs responses to the request for additional information (RAI) regarding the renewal of the Three Mile Island Unit 2 (TMI-2) Independent Spent Fuel Storage Installation (ISFSI) license (SNM-2508). The DOEs RAI response is dated September 26, 2018 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML18283A222).
The meeting was noticed on November 16, 2018 (ADAMS Accession No. ML18320A267).
Discussion The list of meeting attendees is provided in Enclosure 1. The meeting discussion followed the meeting agenda, which is provided in Enclosure 2. The NRC staff asked DOE for clarification of responses on RAIs 2-1, 2-2, 2-3, 2-4, 2-5, 3-4, 3-5, 3-6, 3-7, 3-8, and 3-9, and discussion between DOE and NRC representatives followed.
CONTACT: Kristina Banovac, NMSS/DSFM (301) 415-7116
RAI 2-1 response. The NRC staff asked about the two different revisions for the fabrication drawing of the ISFSI basemat and approach slab (i.e., Drawing 219-02-5200, Revision 3, Sheet 1 and Revision 2, Sheet 2). DOE noted that each drawing has an overall revision number, but each sheet of the drawing has a separate revision number noting the latest revision to that particular sheet. The NRC staff also asked whether proposed license condition # 17 should address the final safety analysis report (FSAR) changes discussed in the RAI 2-1 response, in addition to the FSAR supplement in Appendix C to the license renewal application (LRA). DOE noted that it does not object to a change in the proposed condition but believes it is not necessary, because the Licensing Document Change Request (LDCR) submitted to the NRC on October 2, 2018 (ADAMS Accession No. ML18303A125), approves the FSAR changes (discussed in the RAI 2-1 response) under the DOE process for controlling licensing basis documents. By DOEs process, the changes in the LDCR will be included in the next FSAR update submitted to the NRC (either the next biennial update or the update per the future renewal license condition #17, whichever comes first). The NRC staff noted that it will consider whether a change to the proposed condition is needed.
RAI 2-2 response (also related to RAI 3-4 response). The NRC staff asked about the specific location of the dose rate measurements referenced in the RAI response and the difference between the measured dose rates at the surface of the vent ports filter housing and those measured in the general vicinity of the filter housing. There was also some discussion about the 1200 mrem/hr limit in technical specification (TS) 3.2.2 versus the measured and calculated dose rates. DOE noted that it takes measurements at surface locations to determine compliance with the TS limits. Additional measurements are taken for the radiological environmental monitoring program, and DOEs procedure provides for measurements of the highest dose rate within the general vicinity of the filter housing on the vent port; these vicinity dose rates can be higher than the surface dose rates because of shine around the vent ports filter housing.
The NRC staff noted that the supplemental dose analysis considers the worker dose for 1 dry shielded canister (DSC), but if all 29 DSCs are considered, and the calculated HEPA filter outer surface dose rate of 109 mrem/hr (which is well in excess of actual measured dose rates) cited in the RAI response is applied, the calculated dose could exceed the worker dose limits in Title 10 of the Code of Federal Regulations (10 CFR) Part 20. The staff also noted that, in addition to the transfer operations considered in the RAI response, other activities to support technical requirements, such as those addressing the vent housing seals, would also contribute to doses due to dose rates from the filter vent housing. As part of that discussion, the NRC staff asked if elastomeric seals are currently in service at the TMI-2 ISFSI, and DOE noted they are not. DOE provided a description of how it generally ensures worker doses do not exceed regulatory limits and radiation exposures are kept as low as is reasonably achievable, per its radiation protection program. Before conducting work at the TMI-2 ISFSI, DOE takes dose rate measurements in the vicinity to plan stay times, number of workers, use of temporary shielding, badging of workers, etc. DOE also noted that its compliance with 10 CFR Part 20 worker dose limits is based on measured dose rates and not calculated dose rates.
The NRC staff also asked about the purge port shield block appearing to be scoped out of the renewal. The NRC staff noted that both the FSAR shielding analysis and the supplemental shielding analysis rely on the assumption of similarity between the vent port and the purge port and that dose rates for the vent port will bound those for the purge port. DOE provided clarification that, in the FSAR shielding analysis and the supplemental shielding analysis, the vent port dose rates bound purge port dose rates. The NRC staff noted that the validity of that assumption appears to rely on the presence of the purge port shield block. DOE provided
further explanation that the vent port is located in a similar position as the purge port in terms of its relative position to neighboring TMI-2 canisters. Therefore, the contributions from the sources are considered similar for both. The vent port also has a wider penetration into the shield plug lending more conservative dose rates than the purge port. DOE further explained that the validity of the bounding vent port over purge port dose rate assumption does not rely on the presence of the purge port block. DOE offered to provide this information formally or any other information, such as the specific location of referenced dose rate measurements, if requested. The NRC staff will consider whether any additional specific clarifications are needed from DOE.
RAI 2-3 response. The NRC staff noted it wished to edit the proposed license condition # 19 language of normal storage operations to storage operations to be consistent with the current language in the TS. DOE noted it does not object to this change.
RAI 2-4 response. The NRC staff asked whether the OS197 transfer cask subcomponent scoping results are included in the FSAR supplement (Appendix C of LRA), as they were not included in the transfer cask scoping section in Section C.2.3.3 of LRA. DOE clarified that the incorporation by reference of the OS197 scoping results is located in Section C.2.6.3 of the LRA, with the reference to Appendix 2C and 2E (of the renewal application for the Standardized NUHOMS system, Certificate of Compliance No. 1004, Revision 3), which includes the subcomponent scoping for the OS197 transfer cask. The NRC staff also noted that, per the proposed OS197 transfer cask AMP, DOE may be responsible for the AMP transfer cask inspection prior to use, rather than the transfer cask owner as noted in the RAI response. DOE noted that, as part of its quality-controlled procurement process for important to safety items, it would ensure that the appropriate AMP inspections are completed prior to use.
RAI 2-5 response. The NRC staff noted it has several questions about the RAI response and the supplemental analysis that was conducted to support scoping out the transfer cask spacers from the renewal. The RAI response noted that no spacers currently exist, and new spacers would need to be fabricated if the transfer cask were used in the future at the TMI-2 ISFSI (e.g.,
for retrieval operations from storage). Given this fact, the NRC staff asked if a license condition limiting the age of spacers (similar to the proposed condition # 20 for the MP187 transfer cask) was appropriate, instead of further discussing the supplemental analysis and NRC staffs questions on it. Under this approach, the spacers would scope into the renewal, and the license condition would preclude the need to conduct an aging management review of the spacers.
DOE noted that it would consider the approach and whether to propose a license condition and make any corresponding changes to the LRA or FSAR supplement (e.g., scoping tables). The NRC staff noted that DOE should consider its future plans for use of the spacers, as the change control process if DOE wishes not to use the spacers will be different if the spacers are included in a license condition (e.g., requiring a license amendment instead of a potential 10 CFR 72.48 change).
RAI 3-4b response. The NRC staff asked about the exact locations of two neutron dose rate measurements that were taken and reported in LRA references 3.11.102 and 3.11.103. DOE noted it could provide this information if requested by the NRC staff. The NRC staff will consider whether any additional specific clarifications are needed from DOE.
RAI 3-5 response. The NRC staff noted that it does not agree with the justification for excluding aggregate reactions as a credible aging mechanism. The NRC staff asked whether inclusion of reactions with aggregates in the FSAR supplement (Section C.2.6.2 of the LRA) was adequate for capturing that the aggregate reactions aging mechanism was indeed considered credible.
DOE clarified that Section C.2.6.2 of the LRA includes one list of all aging mechanisms that were evaluated and another list of aging mechanisms that are considered credible and will be managed; the aggregate reactions aging mechanism is not included in the latter list. DOE and the NRC staff discussed options for proceeding and how this should be reflected in the design bases. As DOE is ultimately using the American Concrete Institute (ACI) 349.3R second tier acceptance criteria in its horizontal storage module (HSM) AMP, DOE and the NRC staff will further consider whether the HSM AMP could be modified to include evaluation of aggregate reactions in any corrective actions triggered by exceeding the AMP acceptance criteria.
RAI 3-6 response. The NRC staff asked why the dose analysis was only conducted for the DSC vent housing and compared to the TS limit and not also conducted for the HSM rear access door and compared with the TS limit for the door. The NRC staff also asked if the removal of Licon, as considered in the analysis, could change the structure of the TMI-2 canister such that it could change the shielding analysis and noted that such had been considered in the supplemental criticality analysis. DOE noted that the Boral shroud contains the radioactive material, and the shroud is structurally independent of the Licon. The NRC staff also asked about the collapse of the fuel canisters outer shell. DOE noted that it did consider reconfiguration (i.e., collapse of the fuel canisters outer shell to be immediately around the shroud) in the criticality analysis to try to create the most reactive geometry for conservatism in the analysis, but it felt it was not necessary for the shielding analysis. The NRC staff will consider whether any additional specific clarifications are needed from DOE.
RAI 3-7 and 3-8 responses. In response to NRC staff questions, DOE clarified that the Boral shroud does extend the whole length of the fuel canister cavity. DOE used 1740 pounds in the analysis, as that is the maximum weight of the fuel debris that is in any of the loaded fuel canisters. The NRC staff noted concerns with the benchmark analysis. These concerns included sufficiency of the trending analysis, with a comment that at least an additional trend with respect to the hydrogen-to-fissile atom ratio should be included. The concerns also included the use of benchmarks with absorber materials that are not relevant to the analysis (i.e., materials which are not also in the fuel canister analysis). DOE noted that most of the benchmarks are for reactors, not spent fuel storage, and there is adequate margin for the USL calculation. The NRC staff will consider whether any additional specific clarifications are needed from DOE.
RAI 3-9 response. The NRC staff asked for clarification on the drying process for each canister and how each canister was confirmed to meet the required maximum residual water limits (for both bound and unbound water) to ensure compliance with the assumptions in the analysis.
The NRC staff noted that it is still not clear what was actually done and what criteria were used to ensure the canisters were sufficiently dry in a consistent manner. DOE noted that it can provide an explanation of what was done for drying, including the criteria for ensuring the canisters met the residual water limits, and how the analysis assumptions are confirmed, if the NRC staff requests this information. The NRC staff will consider whether any additional specific clarifications are needed from DOE.
After the discussion of the specific RAI responses was completed, the NRC staff noted that it will consider the information and clarifications provided by DOE during the meeting and will determine whether additional specific clarifications are needed from DOE for the NRC staff to complete its safety evaluation of the LRA. DOE and the NRC staff recognized the benefit of an NRC correspondence communicating any additional specific clarifications the NRC staff needs, for clarity and transparency. The NRC staff noted that it would attempt to provide such a correspondence to DOE in early 2019. The NRC staff also noted that, if any additional changes
are made to the LRA, the NRC staff would need a final FSAR supplement (Appendix C of LRA) and final versions of the LRA tables referenced in the FSAR supplement to reference in license condition # 17.
After DOE and NRC representatives completed their discussion, the public was given the opportunity to make comments or ask questions of the NRC. Ms. Shannon Chu requested the ADAMS Accession No. for the DOE RAI response, and the NRC staff provided the information after the meeting.
Action Items/Next Steps The NRC staff will consider the information and clarifications provided by DOE during the meeting and prepare a correspondence requesting any specific clarifications it needs to complete its safety evaluation in early 2019.
Docket No.: 72-20 CAC/EPID Nos.: 001028/L-2017-RNW-0019 and 000993/L-2017-LNE-0007
Enclosures:
- 1. Meeting Attendees
- 2. Agenda
ML18360A186 OFFICE NMSS/DSFM NMSS/DSFM NMSS/DSFM NAME KBanovac WWheatley JWise for MRahimi DATE 12 / 17 / 18 12 / 19 / 18 12 / 21 / 18
MEETING ATTENDEES Meeting (via teleconference) with U.S. Department of Energy (DOE) to clarify the responses to the request for additional information regarding the renewal of the Three Mile Island Unit 2 Independent Spent Fuel Storage Installation license (SNM-2508)
December 6, 2018, 2:00 - 4:00 p.m.
Kristina Banovac NRC/NMSS/DSFM/RMB Ricardo Torres NRC/NMSS/DSFM/RMB Meraj Rahimi NRC/NMSS/DSFM/RMB Michel Call NRC/NMSS/DSFM/CSRAB Caylee Kenny NRC/NMSS/DSFM/CSTB Steven Wahnschaffe DOE-Idaho Operations Office Scott Ferrara DOE-Idaho Operations Office Brian Gutherman Gutherman Technical Services Jeffery Long Spectra Tech, Inc.
Chris Backus Orano Federal Services Erik Gonsiorowski Orano Federal Services Sarah Gibboney Orano Federal Services Shannon Chu Public/Electric Power Research Institute Jeremy Renshaw Public/Electric Power Research Institute Bret Leslie Public/Nuclear Waste Technical Review Board Robert Heimer Public/American Electric Power
MEETING AGENDA Meeting with U.S. Department of Energy (DOE)
December 6, 2018 2:00 p.m. - 4:00 p.m. (Eastern Standard Time)
Two White Flint North Building, Room T-4D24
Purpose:
Meeting (via teleconference) with DOE to clarify the responses to the request for additional information regarding the renewal of the Three Mile Island Unit 2 Independent Spent Fuel Storage Installation license (SNM-2508).
Agenda:
Welcome, introductions, and meeting objectives Discussion Public questions or comments Wrap-up and closing remarks Meeting adjourned