ML18331A184
| ML18331A184 | |
| Person / Time | |
|---|---|
| Site: | 07109375 |
| Issue date: | 11/27/2018 |
| From: | Pierre Saverot Spent Fuel Licensing Branch |
| To: | Yoira Diaz-Sanabria Division of Spent Fuel Management |
| Saverot P | |
| Shared Package | |
| ML18331A181 | List: |
| References | |
| EPID L-2017-LLA-0059 | |
| Download: ML18331A184 (4) | |
Text
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 November 27, 2018 MEMORANDUM TO: Yoira Diaz-Sanabria, Acting Deputy Director Division of Spent Fuel Management Office of Nuclear Material Safety and Safeguards FROM: Pierre Saverot, Project Manager /RA John McKirgan Acting for/
Spent Fuel Licensing Branch Division of Spent Fuel Management Office of Nuclear Material Safety and Safeguards
SUBJECT:
SUMMARY
OF NOVEMBER 13, 2018, MEETING WITH HOLTEC INTERNATIONAL
Background
On September 23, 2015, Holtec International (Holtec) submitted an application for the Model No. HI-STAR ATB 1T package. Meetings were held on November 24, 2015, January 19, 2016 and March 16, 2016, to discuss the request for supplemental information (RSI) issued by staff on November 10, 2015, regarding a benchmark test program, the general acceptability of the test model, and test sequences. Drop tests were conducted at Sandia National Laboratories on September 12-14, 2016, and Holtec submitted a new application by letter dated February 6, 2017. An RSI letter was issued on March 21, 2017, followed by two requests for additional information (RAI) on August 9, 2017, and May 29, 2018, respectively. Holtec requested the November 13, 2018 meeting, as a continuation of the August 24, 2018 meeting, to present the progress made in resolving the current structural and containment design issues of the package.
The November 13, 2018 meeting was noticed on September 25, 2018 (ML18268A016). The meeting attendance list and the presentation are provided as Enclosure Nos. 1 and 2, respectively.
Discussion The Model No. HI-STAR ATB 1T package is a rectangular package, 3.7 m long, 1.8 m wide, and 2.9 m high with a gross weight of 116 metric tons, designed for the transport of up to 12 tons of Greater Than Class C (GTCC) waste such as core grids, core shrouds, shroud heads, top guides, etc.
CONTACT: Pierre Saverot, NMSS/DSFM (301) 415-7505
Y. Diaz-Sanabria Several design changes, including new aluminum impact absorbers, reconfigured lid spacer bars and maintenance cover, the addition of a high strength cladding to reinforce the seal region for the closure lid and the flange, are being implemented to address the plastic deformation in the closure region. While inelastic strains are not permitted in the seal region, the American Society of Mechanical Engineers Appendix FF strain limits apply for the containment wall plate, the closure lid and the top flange. Holtec said the inelastic deformations should not cause unloading of the closure seal beyond its useful springback, i.e., 0.07 per manufacturer data.
Staff had several questions on the proposed design of the recess (the current design includes a step-down in the lid), its fabrication with a strip-cladding technique, the performance of non-destructive evaluations (NDE) in that area and how imperfections could be checked. Staff mentioned the case of the TRUPACT-III, where initially debris could get into the seal with full contact lost for a few milliseconds, and noted that some results from the Holtec analysis, still continue to show plastic deformation at the closure.
Regarding the true stress-strain curves, staff noted that the position paper, referred to by Holtec and submitted with the HI-STORM FW license application, is applicable for stress criteria only.
Staff also said that the approach proposed to be used to develop the true stress-strain curves, as input to LS-DYNA, is not acceptable. The power law equation that describes the flow curve of metal in the plastic deformation region needs to be based on material testing. Specifically, the constants K and n in the equation need to be determined from the mean test values obtained from material testing. Holtec cannot determine these constants analytically.
Staff noted that the maintenance cover is screwed to the aluminum impact absorbers and that Holtec has added additional drop simulations that were requested by staff. One of those simulations, i.e., the 30 ft drop, top CGOC followed by a 1 m puncture, still shows there are strains in the seal seating surface on the top flange and on the seal grooves on the closure lid.
Thus, Holtec was reminded that the focus of future design modifications should be on those areas, because the application shall clearly demonstrate that positive closure is ensured at all times by the seals.
Staff noted that progress has been made to resolve the current structural and containment issues for this package. However, it is also clear that much more work has to be done to ensure a successful licensing approach with a demonstration of the sealing capability of the package.
Current and future design enhancements, including materials test data still to be acquired, cannot be construed as a 2nd round RAI response, and the review will be terminated if additional requests for information have to be issued. Staff believes that only a new application will provide the cohesiveness and consistency needed to support staffs regulatory findings.
Staff made no regulatory commitment during the meeting.
Docket No. 71-9375 EPID L-2017-LLA-0059
Enclosures:
- 1. Meeting Attendees
- 2. Presentation
Y. Diaz-Sanabria
SUBJECT:
SUMMARY
OF NOVEMBER 13, 2018, MEETING WITH HOLTEC INTERNATIONAL, DOCUMENT DATE: November 27, 2018 DISTRIBUTION: SFST r/f, MLayton, RPowell, RI BBonser, RII MKunowski, RIII JKatanic, RIV G:\SFST\Saverot\HI STAR ATB 1T \meeting summary November132018.doc; HI-STAR ATB 1T Structural Design Qualifications presentation.pdf ADAMS No.: ML18331A181 MEMO: ML18331A184 ENCL 2: ML18331A183 OFC SFM E SFM C SFM NAME PSaverot SFigueroa JMcKirgan DATE 11/14/2018 11/15/2018 11/27/2018 OFFICIAL RECORD COPY
Meeting Between HOLTEC and the Nuclear Regulatory Commission November 13, 2018 Meeting Attendees NRC/NMSS/DSFM Pierre Saverot Antonio Rigato Gordon Bjorkman Joe Borowsky John Wise David Tarantino HOLTEC Chuck Bullard Venkat Prabhala Robert Mahorter Enclosure 1