Dosimetric specification of mixed neutron-photon fields at Czech interim stores for spent nuclear fuel

The objective was to describe dosimetric characteristics of neutron and photon component of mixed fields at three dry interim stores for the spent nuclear fuel situated in territories of two Czech nuclear power plants. Mixed fields depend mainly on the residual thermal power of the loaded fuel, but they are also influenced by the type of CASTOR casks used in each store. To determine values of ambient dose equivalent rate due to neutrons and photons around CASTOR casks, common area dosemeters were employed. As the neutron component of these fields was dominant, neutron spectra were measured by means of the Bonner spheres spectrometer among a few groups of four casks and on their lids. The values of ambient dose equivalent rate derived from neutron spectra were compared with those obtained by area dosemeters. To give an idea about dosimetric situation at the stores, ranges of ambient dose equivalent rate measured around casks are presented together with ratios of this quantity for neutrons to photons. (author)