Assessment Of Occupational Radiation Exposures: A Case Study Of Nuclear Moisture-density Gauge In Construction Industry In Kenya

Abstract

In construction industry, nuclear technologies are widely used in quality control; use of nuclear gauges in direct measurements of in-situ moisture and density of compacted granular pavement layers. In Kenya, nuclear gauges are usually recommended for use in most construction projects, but the use of these equipment are not fully integrated in the construction industry to date, partly due to alleged fear of radiation exposures. This research study sought to investigate the safety of construction workers using the nuclear gauge in Kenya for their occupational exposures as well as general public at various construction sites. The methodology used in the study, involved radiation exposure measurements and the use of questionnaires. A portable multi-purpose survey meter RADOS RDS-110, suitable for detecting and measuring small quantities of gamma, x-ray and beta radiation was used in this study. Radiation exposures measurements were done between 9th September 2015 and 10th October 2015 at a construction site in Marsabit County-Kenya; Lake Turkana Wind Power Project. Radiation dose measurements were taken in-situ during density measurements at 0 m, 5 m and 10 m interval relative to the nuclear density radiation source and at 00, 900 and 1800 angular orientations respectively, relative to the front phase of the nuclear gauge equipment. The calculated annual effective doses were 2.9±0.3 mSvyr−1, 1.4±0.1 mSvyr−1 and 0.5±0.1 mSvyr−1 for 0 m, 5 m and 10 m linear intervals respectively, compliant to occupational limits. Statistical analysis (ANOVA) showed no significant difference exists between measurements in the angular variation. However, the radiation levels were considered a radiological exposure risks at 7.5 m for general public exposure. The overall compliance for radiation safety, amongst the 31 respondents who use nuclear gauge operators was slightly above average at 51%; about a third of the users were untrained, 79% use film badge personal radiation dosage monitoring, surveillance by the regulator for safety compliance was at 59%, whereas use of portable survey meters to monitor radiation was at 42%. In overall, the study, recommends for improvement on the use of the nuclear gauge equipment including training of operators on awareness on radiation safety and monitoring, etc. Key words: Radiation safety, personal radiation exposure and monitoring, nuclear density gauge.