Neutron area monitoring at storage bunkers of density/moisture gauges

Abstract

Previous studies remarked the need of performing neutron personal dosimetry, together with gamma dosimetry, when using portable density/moisture gauges that are normally equipped with gamma and neutron sources. The convenience of our Poly-Allyl-Diglycol-Carbonate (PADC) based neutron dosimeter to perform long-term routine survey of all workers involved in the transport, maintenance and usage of these gauges was also corroborated in the past. This complete dosimetric control offers the possibility to quantify simultaneously individual neutron and gamma doses of workers operating such devices, especially in the most frequent cleaning and maintenance (shutter lubrication) operations of the gauges or in emergency situations that may lead to radiological risk of the persons involved. Another aspect to be considered, from the radioprotection point of view, is the optimization of the occupational and public exposure in the storage bunkers of the gauges. In this work, three storage bunkers, located at three different factories of the PAYMA Cotas S.A.U company, have been monitored for three months using several units of our PADC based neutron dosimeter. Special care has been taken to study also offices near the bunkers with high occupancy rates and passage zones, such as toilets and access areas. Results for all monitored points inside and around the three storage bunkers are presented. Neutron doses inside the bunkers could be relatively high depending on the specific conditions (geometry configuration, localization and shielding composition) of the considered bunker and the number of portable gauges stored.