ML21252A493
| ML21252A493 | |
| Person / Time | |
|---|---|
| Site: | 07109386 |
| Issue date: | 10/13/2021 |
| From: | Pierre Saverot Storage and Transportation Licensing Branch |
| To: | Geoffrey Miller Division of Fuel Management |
| P Saverot NRC/NMSS/DFM/STLB 3014157505 | |
| Shared Package | |
| ML21252A489 | List: |
| References | |
| Download: ML21252A493 (6) | |
Text
C. Rega UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 MEMORANDUM TO: Geoffrey Miller, Acting Deputy Director Division of Fuel Management Office of Nuclear Material Safety and Safeguards FROM: Pierre Saverot, Project Manager Storage and Transportation Licensing Branch Division of Fuel Management Office of Nuclear Material Safety and Safeguards
SUBJECT:
SUMMARY
OF AUGUST 31, 2021, MEETING WITH NATIONAL NUCLEAR SECURITY ADMINISTRATION
Background
On August 31, 2021, an Observation Public Meeting was held by teleconference between the NRC staff and representatives from the National Nuclear Security Administration (NNSA),
Holtec International (Holtec), and Pacific Northwest National Laboratory (PNNL) to present the Model No. HI-STAR PBT cask that will be used for the transport of Tritium Producing Burnable Absorber Rods (TPBAR) from the Watts Bar Units 1 and 2 to the Tritium Extraction Facility at the Savannah River site. A first meeting was held on August 20, 2019, and a second Observation Public Meeting was held on March 31, 2021. This 3rd Observation Public Meeting was noticed on July 21, 2021 in Agencywide Document Access and Management System Accession No ML21201A289.
The attendance list and the publicly available presentation slides are provided as Enclosure Nos. 1 and 2, respectively.
Discussion The Model No. HI-STAR PBT package is a new package for road transport of TPBARs to the Savannah River Tritium Extraction Facility. The package, designed to accommodate the maximum helium inventory from rods with a peak of 1.2 g of tritium, will hold a maximum of 4 canisters, each containing 300 TPBARs, but also allows for a partial loading of 1 to 3 canisters.
CONTACT: Pierre Saverot, NMSS/DFM 301-415-7505October 5, 2021 Signed by Saverot, Pierre on 10/05/21
G. Miller 2
The applicant is designing the package for a maximum heat load of the package is 1.753 kW.
i.e., 1.46 W/TPBAR. Staff questioned this number in view of what is stated in Section 3.5.2.1 of NUREG 1609, Supplement 2: the TPBAR heat load 30 days after removal from the reactor is estimated to be 3.35 W/TPBAR and for purposes of conservatism, the 30-day value should be used for all thermal analyses, throughout
Staff said that, if 3.35 W/TPBAR for 1200 TPBARs had been used in accordance with NUREG, the decay heat would be 4.02 kW, i.e., more than twice what the package is tentatively designed for. PNNL staff responded that they had obtained decay heat values different from those in the guidance and said they may not ship TPBARs that had been out of the reactor for less than 60 days. Staff pointed out that, even in that case, the calculations presented show that the applicant used 1.461 W/TPBAR, which is still less than the value of 2.31 W/TPBAR for the 90-day time interval in the NUREG-1609 supplement 2 guidance. Staff concluded this exchange by reiterating the need to provide a full justification of every data provided in the application, including the decay heat value (W/TPBAR) used to calculate the total decay heat for the package, as well as a demonstration that the source term (and/or time out of the reactor),
results in a lower decay heat per TPBAR than what is stated in the guidance.
Staff also said the applicant could always use a higher decay heat in the thermal analysis, but this would necessitate a few package design changes since (i) there is really not much margin on the impact limiter foam during normal conditions of transport (NCT) and (ii) the seals are over the no-time-limit for hypothetical accident conditions (HAC). Since the maximum seal temperature exceeds the maximum seal temperature limit with no time limits, staff said the applicant shall explain (i) how long the seals will be capable of maintaining a leak-tight containment at this maximum temperature and (ii) the reason(s) why the cask lid seal reaches a much higher temperature than the vent and drain port seals. Alternatively, the applicant could potentially reduce the number of TPBARs to be loaded in the package.
Staff requested that the application includes a full technical justification of any general consideration statements such as there is no credible hydrogen generation or tritium release per year in the consolidation canister is found to be about 1.4%, and, therefore, flammability is not a concern. Staff also requested that the application includes (i) data sheets for General Plastics LAST-A-FOAM FR-3700, (ii) the literature and guidance used by the applicant to calculate the vents sizes and locations, and (iii) the details of the foam combustion modeling during HAC, based on test data.
Regarding the statement by the applicant that all component temperatures and pressures meet their respective limits under all conditions of transport, the staff reminded the applicant to follow the guidance in Section 3.5.4.2 Maximum Normal Operating Pressure, as well as its referenced sections of NUREG 1609 Supplement 2: for example, Section 3.5.5.3 recommends that, as an absolute worst-case condition, the applicant should assume that all TPBARs fail with a loss of 100% of the total tritium inventory. It is not certain, from the presentation slides, that the applicant considered this topic. Also, the applicant should provide the maximum temperature for the impact limiter foam, and the maximum allowable temperature limit (not only the bulk values and bulk value limits, as shown in the presentation). Staff also noted that the maximum temperatures for NCT conditions should not in any case exceed the maximum temperature limits.
G. Miller 3
Staff wondered how the applicant determined a maximum allowable TPBAR temperature of 650°F and if this 650°F value was used for the structural analysis or if 400°F (the equilibrium temperature for TPBARs during shipment, as stated in the guidance) was used in the calculations.
The applicant clarified that the outer shell ribs were included in the thermal model. Staff noted that the containment shell, baseplate and top forging are connected through full-penetration welds; Staff reminded the applicant that containment welds, which are part of the containment boundary, should not only be pressure-tested, as planned, but also be helium leak-tested.
Further, staff reminded the applicant that the containment welds should also be explicitly shown with all pertinent information on the licensing drawings. Staff said that, for packages that contain TPBAR, there are specific considerations that should be given to leak testing (i.e.,
periodic, maintenance and pre-shipment leakage rate tests) and asked if those were detailed in the application.
Staff requested that the data supporting the NCT and HAC temperature limits of all containment seals (lid, vent port and drain port seals) be included in the application, as well as the temperature-dependent properties of the foam.
Staff cautioned the applicant on an incorrect interpretation of the guidance when mentioning acceptance criteria without gross plastic deformation after impactive events because the guidance is unambiguous on the absence of plastic deformation. The shielding evaluation was not addressed for lack of time, but the staff did mention that lead slump and streaming considerations shall be addressed.
Staff expressed a healthy skepticism when Holtec said that two packages will be fabricated, at one-year intervals, before the issuance of a possible certificate in late 2023, in view of (i) possible package design changes and licensing drawings modifications, (ii) a foam impact limiter design not previously certified with potential supplemental testing required, or (ii) any topic stemming from the technical review.
No regulatory commitments were made during this meeting.
Docket No. 71-9386 EPID L-2021-NEW-0009
Enclosures:
- 1. Meeting Attendees
- 2. Presentation Slides G. Miller 4
SUBJECT:
SUMMARY
OF AUGUST 31, 2021, MEETING WITH NATIONAL NUCLEAR SECURITY ADMINISTRATION DOCUMENT DATE: October 5, 2021
DISTRIBUTION:
DFM r/f SHelton, NMSS ADimitriadis, RI BDesai, RII DHills, RIII GWarnick, RIV
ADAMS Package No.: ML21252A489 ML21252A493(Memo and Enc1) ML21252A490(Encl2)
OFFICE NMSS/DFM NMSS/DFM NMSS/DFM NAME PSaverot WWheatley JMcKirgan DATE 10/05/2021 09/14/21 10/01/2021 OFFICIAL RECORD COPY Meeting Between National Nuclear Security Administration and the Nuclear Regulatory Commission (NRC)
August 31, 2021 Meeting Attendees
NRC/NMSS/DFM Pierre Saverot Patrick Koch JoAnn Ireland Michel Call Jimmy Chang Loren Howe Shikha Kumar Darrell Dunn
HOLTEC INTERNATIONAL Andrew Fernsten Kishore Gangadharan Chuck Bullard Behrooz Khorsandi John Zhai Daniel Thomas Chuck Bullard Raja Maheedhara Abrar Mohammad Faisal Odeh
PNNL Laurie Martin Randall Storms Harold Adkins Laura Hay James Fort Peter Sakalaukus Brian Koeppel
NNSA Chad Thompson Becky Sipes Urszula Christner Audrey Nguyen
Enclosure 1
ML21252A489; Memo ML21252A493 OFFICE NMSS/DFM/STLB NMSS/DFM/STLB NMSS/DFM/STLB NAME PSaverot PS JMcKirgan JMPSaverot PS DATE Sep 30, 2021 Oct 5, 2021 Oct 5, 2021