LIFE-II: A COMPUTER ANALYSIS OF FAST-REACTOR FUEL-ELEMENT BEHAVIOR AS A FUNCTION OF REACTOR OPERATING HISTORY.

Abstract The LIFE-II computer code provides a detailed thermal, radiation, and mechanical analysis of cylindrical fast-reactor fuel-element behavior as a function of the actual reactor operating history. Materials behavior models of the effects of fuel restructuring, fuel cracking and hot pressing, migration of fuel constituents, fuel swelling due to solid and gaseous fission products, fission-gas release, fuel-cladding interactions, and cladding swelling due to void nucleation and growth, are included in a generalized plane-strain iterative procedure. As a result, LIFE-II predicts the thermo-elastic, creep, and swelling deformations of the fuel element as a function of the reactor power and coolant temperature history. Comparison of LIFE-II calculations with results from actual fuel-element irradiations in the EBR-II reactor demonstrate the sensitivity of fuel-element performance to reactor operating cycles. Sensitivity analyses are also being performed to indicate the most critical areas in which improved fuel-element material and performance data are needed. The LIFE-II code is a realistic and versatile design tool for the prediction of fast-reactor fuel-element behavior.