The development, design, and operation of nuclear reactors require the accurate prediction of (a) fission rates and burnup for fuels and (b) neutron exposure for neutron-induced property changes for fuels and materials. Goal accuracies of as low as 1% (1σ) have been set for the determination of fission rates, burnup, and neutron fluences for the fast-reactor development program. Based on the discussion of the status of fuels and materials fast-reactor dosimetry data development and testing, attainable goal accuracies presently appear to be in the range of 2 to 5%. Significant progress has been made in achieving high-accuracy measurements through a coordinated interlaboratory effort of integral measurements in low- and high-intensity neutron fields. A few of the major accomplishments of this interlaboratory work are as follows.

  1. identification and selection of a number of standard or reference neutron fields for study and/or intercomparison
  2. demonstrated absolute fission and nonfission reaction-rate measurements with an accuracy of ±1 to ± 7% (1σ), depending on the reaction and environment
  3. initial data testing to establish the similarity of the high-energy (>2-MeV) shape of two of the neutron fields [the Coupled Fast Reactivity Measurements Facility (CFRMF) and the Mol- ∑∑ secondary standard facility (∑∑)] to that of the 235U thermal-fission spectrum, and the observation of serious discrepancies between measured and calculated spectra
  4. initial data testing of ENDF/B-IV and other evaluated dosimetry cross sections and key fission product fast-fission yield values using newly developed CFRMF and ∑∑ integral data.
Comparisons are made of CFRMF and ∑∑ results with those reported previously for GODIVA and the 235U fission spectrum. Fission yield results are considered, based on measurements in the high-intensity environment of EBR-II. These results are coupled with those from CFRMF, ∑∑, and other neutron fields to more clearly define and document existing uncertainties associated with reaction-rate, fuel burnup, and flux-spectral-fluence determinations in fast reactors.