Radon Measurement using Solid State Nuclear Track Detector (SSNTD)

Abstract

RADON MEASUREMENT USING SOLID STATE NUCLEAR TRACK DETECTOR (SSNTD) The aim of this seminar presentation is to establish a regulatory framework to enforce radiological protection standards for the generation of NORM (Radon) in a bid to ensure the protection of human life and the environment from the hazard of radon accumulation. The presentation is delimited to solid mineral mining operations and petroleum exploration activities with the core objective of explaining how individuals who actively use NORM sources like Radon can comply with section 5 (1,4and 5) of the NNRA’s regulation on NORM, through monitoring of Radon Level. Also, the seminar hopes to vividly explain preventive measures on how members of the public would not receive a dose higher than the annual effective dose and how to prevent accumulation of radon in residential buildings both from licensed sources and from NORM. The importance of the seminar is justified by the rising incidents of cancer deaths in Nigeria. Furthermore, according to statistics, over 40% of Nigerians drink borehole water which does not allow the free release of radon gas into the atmosphere. In addition, inhalation of radon gas and radon in water constitutes internal exposure which is a leading cause of lung cancer deaths, second only to cigarette smoking. Radon and its decay products contributes approximately 55% of average effective dose (NORM) to the population and contaminates the environment during mining and oil exploration, early awareness and mitigation will aid the populace while greatly reduce the alarming levels of cancer. Radon (222Rn) is the most stable of all the radioactive gas in Natural Occurring Radioactive Material (NORM).It exists as 220Ra (Thoron) in the thorium series, as 219Ra (Actinon) in the Actinium series and as 222Rn in the uranium series. The radon daughters are solid and attach themselves to the atmospheric dust, thereby increasing its concentration in the air. Cember,1992 postulates that the probable atmospheric concentration is in the order of 2Bq/m3. Radon gas is an alpha emitter with high LET(Linear Energy Transfer). Also, Radon (222Rn) is a heavy radioactive natural gas which is odourless, colourless, noble gas, generated by radioactive decay of radium. Radon can be detected using a detector. These detectors are of various types and the choice of measurement strategy depends on the purpose for the measurement and the type of facility where it is to be measured. The Solid-State Nuclear Track Detector (SSNTD) functions by using Cellulose Nitrate or CR-39 which can be used as a detecting element for alpha tract detector. Radon diffuses into the container with ATD and alpha particles emitted by radon and its decay product strike the detector and produce a submicroscopic damage tracks. The detector functions as a true integrator and measures the average concentration over the exposed period, the concentration can be converted to an annual effective using a simple formula. The NNRA may wish to enforce SSNTD as a means of measuring radon concentration and enforce its use in allied industries that perform well-logging while enforcing other safety measures. Seminar presented by, Oyeyemi, Samuel M.