In a paper presented at the 5th ASTM-Euratom Symposium, the determination of neturon flux in the light water test reactor at the Nuclear Science and Technology Facility of the State University of New York at Buffalo was reported. In this experiment, dosimetry measurements were made in a mockup of a configuration used for typical metallurgical irradiations. A detailed calculation was also performed to determine the neutron spectrum for correlation of the measured results.

Further measurements have been made using dosimetry capsules inserted into metallurgical experiments. Since the Buffalo reactor has a very low rate of fuel burnup, it is expected that conditions should remain constant except when changes are occasionally made in fuel element locations in the vicinity of the irradiation experiment. Of more significance, perhaps, are changes in the irradiation rig itself, whether due to changes in composition or rig geometry.

Other effects that are of importance to the evaluation of the fluence received by the metallurgical samples are due to gradient effects within the irradiation block, both axial and radial. No measurement has been made of the radial gradients, but these may be estimated using the transport calculation. Measurements of the axial gradients have indicated that these are within tolerable limits (̃10%) due to the limited axial distance filled with samples. In addition, results from dosimetry in the metallurgical tests have been found to be consistent with the dosimetry test results.

It is concluded that irradiation conditions can be well determined for each sample, including gradient and time variation effects. It is recommended, however, that dosimetry measurements of each experiment be continued to ensure highest confidence in exposure results and to guarantee that effects due to changing conditions (as noted above) are recognized.