TY - GEN
T1 - MCNP water physics scoping study to support LWR accident tolerant fuel testing in TREAT
AU - Hill, Connie M.
AU - Bess, John D.
AU - Woolstenhulme, Nicolas E.
AU - Parry, James R.
AU - Bays, Sam E.
PY - 2016
Y1 - 2016
N2 - Preliminary neutronics analysis of the Multi-SERTTA (Static Environment Rodlet Transient Test Apparatuses) in preparation for Transient Reactor Test (TREAT) facility restart operations to support light water reactor (LWR) accident tolerant fuel (ATF) testing revealed a substantial increase in power coupling factor (PCF) with the addition of water into the test module primary containment. Shift in focus from fast reactor fuels historically tested in TREAT to LWR fuels introduces a significantly different neutronics dynamic within the experiment. This paper describes several water physics scoping experiments modeled in MCNP to explore an explanation for the PCF increase, and to gain a better understanding of the observed water phenomenon to inform experiment design. These studies demonstrate that neutron backscatter by water surrounding the fuel specimen creates a flux trap at varying degrees of effectiveness depending on the water thickness, flux density, and the incoming neutron flux energy profile. The impact of the latter two factors is best assessed experimentally for transient conditions. The judicial use of water, just a few centimeters in thickness, surrounding the fuel specimen can significantly, and in some cases dramatically, enhance TREAT core power to experiment fuel specimen power coupling both in steady state and transient conditions. This enhancement is expected to have a positive impact on experiment scope and design flexibility regarding potential limitations due to higher fuel specimen burn-up, number and configuration of test fuel pins, and choice in test train vehicle structural materials for the optimization of safe energy deposition in future ATF experiments.
AB - Preliminary neutronics analysis of the Multi-SERTTA (Static Environment Rodlet Transient Test Apparatuses) in preparation for Transient Reactor Test (TREAT) facility restart operations to support light water reactor (LWR) accident tolerant fuel (ATF) testing revealed a substantial increase in power coupling factor (PCF) with the addition of water into the test module primary containment. Shift in focus from fast reactor fuels historically tested in TREAT to LWR fuels introduces a significantly different neutronics dynamic within the experiment. This paper describes several water physics scoping experiments modeled in MCNP to explore an explanation for the PCF increase, and to gain a better understanding of the observed water phenomenon to inform experiment design. These studies demonstrate that neutron backscatter by water surrounding the fuel specimen creates a flux trap at varying degrees of effectiveness depending on the water thickness, flux density, and the incoming neutron flux energy profile. The impact of the latter two factors is best assessed experimentally for transient conditions. The judicial use of water, just a few centimeters in thickness, surrounding the fuel specimen can significantly, and in some cases dramatically, enhance TREAT core power to experiment fuel specimen power coupling both in steady state and transient conditions. This enhancement is expected to have a positive impact on experiment scope and design flexibility regarding potential limitations due to higher fuel specimen burn-up, number and configuration of test fuel pins, and choice in test train vehicle structural materials for the optimization of safe energy deposition in future ATF experiments.
KW - Accident tolerant fuels
KW - Power coupling factor
KW - TREAT
KW - Transient coupling factor
UR - https://www.scopus.com/pages/publications/84992034610
M3 - Conference contribution
AN - SCOPUS:84992034610
T3 - Physics of Reactors 2016, PHYSOR 2016: Unifying Theory and Experiments in the 21st Century
SP - 443
EP - 454
BT - Physics of Reactors 2016, PHYSOR 2016
PB - American Nuclear Society
T2 - Physics of Reactors 2016: Unifying Theory and Experiments in the 21st Century, PHYSOR 2016
Y2 - 1 May 2016 through 5 May 2016
ER -