NEUTRON AND GAMMA-RAY TOTAL-DOSE RATE DETERMINATION USING ANISN

The National Center for Nuclear Safety and Radiation Control is in the process of acquiring a computer software library based mainly on inte rnationally widely used computer codes. These codes are to be used as basic tools in safety analysis and radiation control and risk assessme nt. A complementary part of this activity is to validate the computer codes and set standard procedures with the limits of confidence for th e different areas of applications of the one or the other code or set of codes. The present work has been then initiated in order to develop a standard shielding calculating procedure to be applied for the diff erent applications of interest to the center, namely: shielding of nuc lear installations, such as the ET-RR-1 reactor, the gamma unit, nucle ar accelerator, radiotherapy units; shielding of nuclear sources (main ly neutron and gamma sources); shielding of transportation containers. In developing such a standard method, the sources of error to the fin al results (i.e. the dose rate and dose rate distribution) have to be identified and the error to be quantified. Through applying the develo ped procedure to benchmark PWR shielding problems, and to documented r esults for fission sources in water and concrete, the levels of confid ence of the procedure in different application areas have been set.