Neutron energy flux spectrum measurements for LEU core of PARR-1

The Pakistan Research Reactor-1 has been converted and upgraded from highly enriched uranium (HEU) to low enriched uranium (LEU) fuel from 5 to 9 MW. An experimental programme was undertaken to measure the neutron energy spectra in the core and at the irradiation facilities of the new core. several threshold activation detectors were irradiated and activity of the foils was measured using high efficiency HPGe gamma ray spectroscopy system. The measured saturation activities were used in the spectrum adjustment computer code SANDBP. A sample energy spectrum for the material test reactor supplied by the International Atomic Energy Agency (IAEA) was used as the input to the SANDBP code, and the final spectra were obtained by iterative adjustment. (author) 7 figs