Spent LWR fuel dry storage in large transport and storage casks after extended burnup

On the way to enabling FRAPCON-3 to model spent fuel under dry storage conditions: The thermal evolution

“…results are not shown since there are synergies between temperature and in-reactor variables, like rod internal pressure and fast neutron fluence, which make the burnup effect hard to be individually analysed. As expected, deformation by creep occurs in the first years in the dry storage and in no case predictions come close to the 1% limit (Spilker et al, 1997). As for the specific observations that can be made through a case-to-case comparison:…”

Modeling of thermal creep behavior in Zr-1.1Nb-0.05Cu alloys

“…Spilker et al [9] proposed an empirical creep model for the experimental data under 80 MPa to 150 MPa at 100°C to 400°C. The creep rates were fitted with a following simplified equation,…”

“…The model matched well with the experimental data ranging 80 MPa to 150 MPa and 350°C to 400°C in Zircaloy-4 tubes. However, the model still missed the proper steady-state creep rate by adopting the following equation of the creep rate as (9) where the strain rate is exponential function of the stress.…”

“…In addition, the model can estimate the long-time creep behavior that would be difficult with a real test, and the behavior under varying creep conditions such as temperature rising or decreasing, stress increase or reduction, etc. Actually, the model estimation of creep has been used in many systems, such as Alloy 617 [15], stainless steel [16], as well as zirconium [9][10][11][12][13].…”

A creep rupture criterion for Zircaloy-4 fuel cladding under internal pressure

“…The estimated circumferential stress (the maximal principal stress) ranges from about 70 to 120 MPa. Although temperature and stress will decrease during storage, long term creep is considered as the relevant deformation mechanism which could potentially lead to a cladding rupture [1][2][3].…”