Preventing Failure in Spent Nuclear Fuel Canisters

Abstract

(702)-895-4328 / FAX (7021-895-3936 ABSTRACT Linear and non-linear stresses and buckling loads in the pintle, top head, canister shell and top plate of two high-level spent nuclear fuel canister models are evaluated under a variety of static and dynamic loading conditions resulting from normal handling. The proposed canister designs are made of 304L stainless steel, having a yield strength of 220 Mpa (32000 p s i) , an ultimate tensile strength of 586 Mpa (85000 psi) and a high resistance to crack initiation. The canisters are 0.0095m (0.375 in) thick, 0.7m (28 in) in diameter and 4.2m (165 in) long. Finite element analysis is used in the stress and stability analysis. Four node thin shell elements and 3-D isoparametric four node thick shell elements are used in modeling the weldment, tophead, pintle, bottom plate and the canister shell. Results obtained from the various types of analysis and the two finite element models, compare favorably within the limitation and applicability of each element type, Results are also compared with theory for some canister loading conditions when a theoretical analysis is possible. Results show that these proposed container models are not adequate to handle stresses and some local and global instabilities resulting from accidental drops, impact between canisters and sudden slippage of the crane cable, during the process of lifting and handling of the nuclear fuel containers. ABSTRACT The thickness and time at failure oithe i O O m m thck overpack and the 9.5mm thick inner container of a Multi purpose canister have been assessed due to loads resulting fiom temperature, overburden, bacldill pressure and seismic loads. Critical stresses at various reduced thicknesses, resuiting h m pitting corrosion over the years of empiacement,