Monitoring

Apparatus for monitoring a volume of waste for radioactive material, the apparatus comprising

• a support, the support being provided with a plurality of detectors for radioactive material;
• a monitoring space in which the volume of waste is provided;
• and
• a data processor for calculating a monitoring result, for correcting the monitoring result for geometry and/or attenuation to give a corrected result and for providing a correction factor for correcting the monitoring result to give the corrected result;
• wherein the correction factor is obtained by a method comprising:
• providing a simulation of an equivalent volume of waste free of radioactive material in an equivalent monitoring space, with equivalent detectors;
• providing a known activity radioactive source at one or more positions in the volume of waste;
• and
• determining the detector response to the source in a position, a comparison of the response and known activity contributing to a correction function for that equal volume, one or more such correction functions providing the correction factor.