ObjectiveTo identify and control radiation risk factors, and quantitative evaluation of the radiationrisk level in iron and steel industry, an investigation was carried for understanding the basicsituation of radioactive substances and radiation protection and management in iron and steelindustry more clearly, with history information about radiation accidents, and the occupationalenvironmental radiation dose and individual absorbed dose level were measured. So that it wasmore reasonable and feasible for determining radiation protection prevention measures andproposals, to achieve the purpose of eliminating or reducing radiation hazards and providingscientific foundation for better in radiation protection.Methods1. Survey and monitoring radiation source: Wuhan Iron and Steel(Group) Corporation wasselected as the typical study object, then survey schedule table was developed for basic currentsituation about iron and steel enterprises. the contents included every units which involvedradiation source, the type of radiation source, radioactive substances, radioactivity and quantity,usage, the status in using or idle, environmental radiation dose, radiation management systemand so on;2. Assessment of occupational radiation hazards: The survey questionnaire was made foroccupational radiation hazards; environmental radiation dose and individual accumulate dosewas monitored in work place, further more the information about the exposure population, thepossibility of exposure, the potential radiation accident, the knowledge and technical skill ofradiation protection were surveyed;3. Prediction of radiation accident by GM(1,1) Model: Collected all the information aboutradiation accidents at the factory in past ten years, The Gray Systemic Forecast Modeltheory,GM(1,1) were applied to carry on an anticipation of radiation accidents in next year, so asto proceed to the next step to identify the predominant types of radiation risk and its level;4. Assessed the level of radiation hazard: Based on the established database information of radiation source, AS/NZS4360:2004, a risk-assessment model with mathematical index matrixtechnique, were matched to the database, and then created radiation risk matrix table, obtainedthe risk index value corresponding risk level, which is to evaluate the radiation hazard degree;5. Radiation risk management system: Synthesize above all analytical results, combinationwith some laws and hygienic standard of China, as occupational disease prevention, radiatepollution prevention, GB18871-2002and GB/T17982-2000and so on, so that radiation safemanagement measure system in Iron and Steel Industry were drawn up, and emergencycountermeasure system for radiation risk accident was formed.Results1. Up to the December31,2009, there were332radiation sources in this iron and steelcorporation in all, moreover119X-ray apparatus and medical processing accelerator were119.The range of radiation activity concentrations was0.0915GBq to1.85TBq; the total radioactivityintensity was12.289TBq. The varieties of nuclear species were60Co,241Am,241Am-Be,85Kr,137Cs and3H-Ti. Among them there were185radiation sources at working, whose totalradioactivity was10.394TBq, maximum was1.85TBq and minimum was0.0925GBq. Also147radiation sources in stock whose total activity concentrations was1.895TBq, and the max onewas0.185TBq, the min0.185GBq. The main categorization of radiation sources is Ⅳ and Ⅴof all, which account for91.27%of all.2. Total87radiation workers were selected as monitor objects, whose effectiveenvironmental individual dose were measured. The range of annual dose was0.568mSv to6.130mSv, Average annual value of individual radiation dose was0.444mSv, and there were80.0%people whose average value of annual radiation dose were under1mSv, annual averagecollective effective dose equivalent were151.410man·mSv. Also, effective dose equivalent of thesilicon steel factory, the cold-rolling mill, the metal structure designing company, the qualitytesting center, the research institute respectively were3.032mSv,1.460mSv,2.438mSv,1.285mSv,1.757mSv (mean was1.893mSv).3. Since1980, there were some radiation accidents which have once happened in the ironand steel corporation, this include:4accidents was that radioactive source were stolen or lose orout of control, and7accidents was that radioactive dose were impermissibly high. However,there were7accidents which happened in last ten years, the accident rank all were generalradiation accident which was the lowest rank. These accidents info-data were applied to fit theGray Model(1,1). It was testified that the Accuracy of model was highly as Ck=0.2059,Pk=1.1000. And then the2011’s value that calculated by the model was0.94. it means, there is0.94accidents which will happen at the iron and steel factory in2011.4. Combined with the risk assessment management model AS/NZS ISO31000:2009, the radiation risk incident of the factory were recognized and identified, which were classified for3types: the cases related to radiation sources or radioactive substance, the cases caused by theprocess of production practice, and the cases that the radiation workers or the publics wereaccidentally irradiated. Among it, three radiation risk factors such as radioactive source werestolen or lose, radioactive substance dose was beyond the limitation of standard in transport,radioactive contamination by waste steel, were Extreme risk level whose risk index was E-76,the factor as occupational irradiation of radiation workers was High risk, whose risk index wasH-56.Conclusions1. Although the level of environmental radiation dose and individual absorbed dose werelower than the limitation of the national standard, the number and kinds of the radiation sourceswere numerous and diverse, and the frequency of use is high. So the potential safe danger wasexistence, and the radiation protection measure must be further consummate.2. Average annual individual effective dose equivalence to the occupational worker in theworkshop of every factory was lower than the national standard limitation(20mSv/a), the factoryof which annual effective dose equivalent for individual and the public both were the highest wasthe silicon steel factory.3. According to the value of GM(1,1) prediction, there will be0.94radiation accident in2011if without more effective measurements.4. The radiation risk factors were diverse and complex, the risk defense were considerablydifficulty. Therefore it was highly necessary to work out the specific radiation risk measure forproduction safety in iron and steel industry, including establishing and perfecting managementorganization, improving Rules and Regulations, reinforcing protection measures, strengtheningoperations management, popularizing the knowledge of radiation prevention and healthmanagement in radiation workers, Periodic safety inspection and supervision system, andscientific system of radioactive accident disposal. |