DEVELOPMENT OF COMPUTER CODE SAFFRON FOR EVALUATING BREACHED PIN PERFORMANCE IN FBRS

In order to evaluate the breached pin behavior in FBR, the breached pi n performance analysis code SAFFRON was developed. Based on the result s of run-beyond-cladding-breach test in EBR-II as a collaborative prog ram between PNC and U.S. DOE, the following behaviors were taken into cosideration; fuel sodium reaction product (FSRP) formation, resultant fuel expansion, breach extension of cladding and release of delayed n eutron precursors into the coolant. Using 3-dimensional elastic analys es by finite element method, breached pin diameter increase is adequat ely predicted with the reduced Young's modulus of the breached fuel. T he delayed neutron signal response in on-line diagnosis was evaluated in relation to the growth of FSRP and breached area enlargement.