Development and application of a safety analysis code for small Lead cooled Fast Reactor SVBR 75/100

Lead cooled Fast Reactor (LFR) is attracting attention due to its advantages in safety. The SVBR 75/100 (Lead-Bismuth Fast Reactor) is a 75-100 MWe concept utilizing Lead-Bismuth eutectic alloy (LBE) as coolant in which the power level depends upon the specific design parameters chosen. A safety analysis code for Lead cooled Fast Reactor.(SAC-LFR), developed to conduct analysis of the thermal-hydraulic behaviors and safety performance of SVBR 75/100, is discussed in this paper. A plant control model which is incorporated into SAC-LFR is developed to simulate the plant control system (PCS) of the fast reactor. In the present work, normal transients such as load following are modeled by SAC-LFR to show that the PCS model is available for simulating plant control in this code. Unprotected foss of flow (ULOF) and unprotected transient over power (UTOP) are simulated by SAC-LFR to test and verify the rector's safety. The results show that SVBR 75/100 has very good inherent safety characteristics due to the neutron and thermal-physical properties of LBE. The key factor that limits its safety performance is the cladding materials. UTOP is more dangerous than ULOF for SVBR 75/100. The safety performance in UTOP could be considerably improved by decreasing the control rod reactivity of SVBR, which can be done thanks to the favorable characteristics of the coolant. (C) 2015 Elsevier Ltd. All rights reserved.