Determination of absolute efficiency of detection systems for fuel pin scanning

The issue of efficiency calibration of scanning systems (scintillation and semiconductor deters) is discussed. Detection efficiencies were calculated for selected fuel pin-collimator-gamma detector configurations by Monte Carlo simulation using a modified CYLMC code. The principles of calculation of the calibration function - dependence of efficiency of gamma detection in the peak of complete absorption of the energy of a quantum ep on its energy, via the total efficiencies Et - are explained. The algorithm of Et calculation by the simulation Monte Carlo method is described in detail. The result includes a series of efficiencies Et for selected fuel pin-collimator-gamma detector configurations. Et calculations were performed for 2 detectors, NaI(Tl) and HPGe, and usually for 2-4 collimator types. The dedicated PalProut code was employed. Its advantages over universal codes such as MCNP are demonstrated