Note on the Benchmark and Validation of the LAHET Code System

Accelerator Driven Transmutation (ADT) engineering systems require a low level of uncertainty at a high confidence level for modeling of neutron generation and transport in complex and massive targets. These uncertainties require large engineering design margins, which are primarily contingencies that increase the facility cost and risk. Much of the uncertainty associated with the codes, in the range of 10% to 12% at the 95% confidence level (CL), is thought to be due primarily to multiple scattering (leakage) of high-energy neutrons and protons in the radial directions of range-thick targets. An experimental program capable of precision measurements of integral neutron multiplicity and source term volume is proposed. (authors)