Thermal Modeling Analysis of SRS 70 Ton Cask

Abstract

The primary objective of this work was to perform the thermal calculations to evaluate the Material Test Reactor (MTR) fuel assembly temperatures inside the SRS 70-Ton Cask loaded with various bundle powers. MTR fuel consists of HFBR, MURR, MIT, and NIST. The MURR fuel was used to develop a bounding case since it is the fuel with the highest heat load. The results will be provided for technical input for the SRS 70 Ton Cask Onsite Safety Assessment.The calculation results show that for the SRS 70 ton dry cask with 2750 watts total heat source with a maximum bundle heat of 670 watts and 9 bundles of MURR bounding fuel, the highest fuel assembly temperatures are below about 263 o C. Maximum top surface temperature of the plastic cover is about 112 o C, much lower than its melting temperature 260 o C. For 12 bundles of MURR bounding fuel with 2750 watts total heat and a maximum fuel bundle of 482 watts, the highest fuel assembly temperatures are bounded by the 9 bundle case.T he component temperatures of the cask were calculated by a threedimensional computational fluid dynamics approach. T he modeling calculations were performed by considering dailyaveraged solar heat flux.

Corrosion of aluminum clad spent nuclear fuel in the 70 ton cask during transfer from L area to H-canyon

“…The cask may contain between 9 to 12 tubes, each containing up to 4 MTR fuel assemblies. The actual number of tubes is driven by the loading requirement which maintains a fuel temperature that does not exceed 263 °C [4].…”

“…Conservative extended times were evaluated to assess the impact on the cladding thickness. For the MTR fuels, a maximum temperature of 263 °C was determined from a heat load of 2,750 watts [4]. As seen in the figure, the MTR fuels would experience cladding thickness losses of approximately 2.5 and 5 mils after storage in the cask for 6 months and 1 year, respectively.…”

Corrosion of Aluminum Clad Spent Nuclear Fuel in the 70 Ton Cask During Transfer From L Area to H-Canyon

“…The shipment of the MTR and HFIR fuels differ in their spatial arrangement, heat flux, and maximum temperature [2][3][4]. These fuels can be characterized as a dispersion of uranium compounds in an aluminum matrix.…”

“…The cask may contain between 9 to 12 tubes, each containing up to 4 MTR fuel assemblies. The actual number of tubes is driven by the loading requirement which maintains a fuel temperature that does not exceed 260 C [4].…”

“…Some residual water will be in the cask from the draining of the fuel elements but still not sufficient to contact the fuel elements on the insert. The maximum fuel temperature will be 180 C for 4 inner HFIR elements and 4 outer HFIR elements [4].…”