Long-term environment monitoring based on MTS-N (LiF:Mg, Ti) and MCP-N (LiF:Mg, Cu, P) thermoluminescent detectors

Abstract

An environmental radiation monitoring system using standard MTS-N (LiF:Mg, Ti) and high-sensitive thermoluminescent LiF:Mg,Cu,P (MCP-N) detectors was applied to control the radiation exposure over the area of the Institute of Nuclear Physics (INP) in Kraków. First environmental measurements using MTS-N detectors began in 1970 at five locations and were continued during the Chernobyl accident at six sites. In March 1987 high-sensitive MCP-N detectors read out in a manual TL reader were first introduced into service at the INP. Since 1992 about 60 locations over an area of the INP were selected for quarterly dose rate measurements, using an automatic TLD system based on MTS-N detectors placed in cards. In 2002 MTS-N detectors were replaced by high-sensitive MCP-N pellets.The dose rate in long-term measurements changed over the last 30 years. The average gamma dose rate over the area of INP in the years 1975–1978 was 63nGy−1. After the Chernobyl accident the gamma dose rate increased to 880nGyh−1. In December 1986 the dose rate at the location place decreased to 103nGyh−1. At present, the average dose rate has returned to the pre-Chernobyl level of about 68nGyh−1. Construction and beam tests of a new isochronous cyclotron at the INP resulted in highly enhanced environmental dose rates at several monitored INP sites. In this work results of almost 11 years of environmental indoor and outdoor measurements with thermoluminescent detectors are summarised.