Dosimetry for fast-reactor irradiation experiments introduces problems not encountered in thermal reactors. The difference in neutron spectrum causes quite different responses among candidate dosimetry materials. Moreover, the damage modes in fast-reactor irradiations and in thermal reactor irradiations may be quite different. This work is aimed at developing adequate methods for spectral determinations, neutron dosimetry, and damage correlation for fast-reactor tests.
Spectral determinations have been performed using a multiple foil activation technique (SAND-II). The SAND-II analysis provides integral neutron flux data with an absolute accuracy of 10 to 30 percent. Intercomparison of analytical results, neutron spectrometer results, and SAND-II determinations indicate reasonable agreement among all three techniques.
While the SAND-II technique provides fluence data, threshold and resonance monitors are simpler to use. A slight modification of monitoring procedures used in thermal reactors suffices for fast-reactor dosimetry. Results from activation monitors in EBR-II and ECEL indicate the feasibility of the monitoring methods.
Damage correlation techniques depend on the mechanisms causing damage. Two of the mechanisms causing property changes during fast-reactor irradiations are displacement production and helium generation by neutron reactions. The fluence dependence for these mechanisms illustrate the need for correlation analyses.