b'2.6 LWR COMPUTATIONAL ANALYSISAccident Tolerant Control RodsPrincipal Investigator: Michael Todosow, BNLTeam Members/ Collaborators: Arantzazu Cuadra, BNLThe combination ofABe chemically and mechanically dvanced accident tolerant control rods that have improvedrobust in reactor temperature and accident tolerant fuel/ thermo-chemical/mechanicalradiation environmentcladding and advancedcharacteristics more than current High miscibility with fuel materials control rods withsilver-indium-cadmium (AIC) orto avoid possibility of re-criticalityimproved thermo- boron-carbide (B4C) control rods, yetDesirable characteristics include:chemical/ mechanicalretain/enhance the poisoning effects/characteristics enhancesrequirements while maintaining High melting temperature: Absorber, the performance andstructural integrity/functionalitycladding/sheathsafety of LWRs in normalduring normal operation and accident Minimal adverse chemical interac-and accident conditionsconditions are a natural complement totions: Between absorber and clad-beyond those achievableaccident tolerant fuel (ATF) concepts.ding/sheath, coolant, etc.by ATF alone. The combination of accident tolerant Minimize adverse mechanical inter-fuel/cladding and advanced controlactions, e.g., Swelling, wear/fretting, rods enhances the performance andballooning, bowingsafety of light water reactors (LWRs) in Resource availability, manufactur-normal and accident conditions beyondability, costthose achievable by ATF alone.Project Description: The neutronic performance of several Requirements and desirableoptions for advance control rods that characteristics of advanced/accidentsatisfied the above criteria was evalu-tolerant control rods include: ated.Impacts considered control rod worth, as well as fuel and moderator Options must: temperature coefficients, and solubleMaintain or exceed absorptionboron worth.capabilities (shutdown, ejected Accomplishments: rod worth, etc.) for desired The neutronic performance of target lifetime options for more robust controlMaintain structural integrity androds (higher temperature, reduced functionality under operating andhydrogen generation, minimize accident scenarios (ability to beadverse chemical and mechanical inserted/withdrawn, handle loads/ interactions) to complement fuels shocks, such as due to SCRAM) with enhanced accident tolerance was evaluated via scoping calculations for a detailed TRITON model of a Westinghouse 17x17 fuel assembly. 150 2019|AFC ACCOMPLISHMENTS'