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ISSN Online: 2377-424X

International Heat Transfer Conference 12
August, 18-23, 2002, Grenoble, France

Convective processes in spent nuclear fuel canisters

Get access (open in a dialog) DOI: 10.1615/IHTC12.4380
6 pages

Sinopsis

In the transfer of spent nuclear fuel (SNF) elements from wet storage pools to dry storage canisters, the elements must be dried and, in some instances, "passified" while they may serve as a thermal energy source. The complicated geometry involved and the range of proposed drying processes lead to a variety of fundamental thermal fluid physics problems to be solved in order to predict the related convective heat and mass transfer from and to the elements reliably. These basic processes can include successively the turbulence distribution from low-Reynolds-number flow in a circular tube, decay of turbulence and velocity in a semi-confined impinging jet, effects of flow through multiple holes on turbulence and velocity fields and decay of turbulence in flow through an array.
Numerical predictions were conducted for a laminar case. Flow visualization and particle tracking experiments were performed with water in a 3/4-scale model of an idealized canister, with and without simulated fuel elements installed. These experiments demonstrated that, despite the conceptual simplicity of the canister design, the flow is very complex. Uneven flow distribution was observed near the fuel rod surfaces and across the array of elements. The velocity and turbulence fields were measured by laser Doppler velocimetry with a 0.6-scale model in the large INEEL Matched-Index-of-Refraction flow system. Emphasis was on the low-Reynolds-number impinging jet and its surrounding flow which provides the initial conditions for flow through the perforated bottom support plate of an SNF basket containing the element array in the canister. These observations are expected to be valuable in assessing codes for the prediction of the convective heat and mass transfer for the elements. This paper concludes with a summary of lessons learned for the benefit of practitioners with SNF dry storage applications.