Adjoint Neutron Flux Research Articles

Radiation Transport in a Liquid-Metal Fast Breeder Reactor During a Loss of Sodium Coolant Reactor Core Disassembly

The time-dependent radiation transport for a demonstration scale liquid-metal-cooled fast breeder reactor that has undergone a severe loss of sodium coolant is calculated with both a discrete ordinates and a diffusion theory solution for the real neutron flux shape. It is found that diffusion theory underpredicts reactivity levels by about $6 when compared to discrete ordinates. It is also found that the use of an initial adjoint neutron flux throughout the transient as a reactivity weighting function could seriously underpredict reactivity levels for a severely degraded reactor core. In both cases, there was an immediate termination of the excursion.The uncertainty of being limited to two fuel fields for an end of equilibrium cycle reactor core in SIMMER-II during the transient was greater than that due to microscopic cross-section shielding factor iteration and interpolation schemes. Fifty-energy-group reactivity coefficients were best duplicated in collapsing to a ten-energy-group set with an entire reactor integrated bilinear neutron energy flux spectrum.

Use of generalized perturbation methods for optimization of reactor design

A method is described which adopts the generalized perturbation theory and programming techniques for optimizing reactor integral parameters, linear or bilinear in the real and adjoint neutron fluxes, after assumption of given constraints. An application of this method to the optimization of the beryllium distribution, with respect to the Doppler effect in a fast ceramic test reactor, is illustrated.

A generalized perturbation method for bi-linear functionals of the real and adjoint neutron fluxes

A generalized perturbation method is derived with respect to ratios of bi-linear functionals of the real and adjoint neutron fluxes of critical multiplying systems. Simple linear analysis for optimization and sensitivity studies are then feasible relative to spectrum and space-dependent quantities, such as Doppler and coolant void reactivity effects in fast reactors.