Assessment of an accident of small amount uranium hexafluoride gas leakage on the influence of human health / 中国职业医学

ABSTRACT

OBJECTIVE: To estimate the amount of the uranium hexafluoride( UF_6) gas leakage in a nuclear fuel element production line,and assess the effect of the leakage on human health. METHODS: The hypothetical accident model was set that the leakage of UF_6 was caused by the hose breakage between valve and pipeline in the UF_6 vaporization process. It took8 seconds for the aerosol to get to the staffs and the staffs needed 1-4 minutes to evacuate. The leakage amount of UF_6 gas and intake of uranium and hydrogen fluoride( HF) were calculated using the estimation formula of gas leakage and internal radiation dose. Its influence on human health was assessed. The radiation hazard and kidney damage induced by the UF_6 exposure,and the chemical hazards to human health caused by HF inhalation were assessed. RESULTS: It is supposed that the staffs need 1 minute to evacuate,the leakage amount of UF_6 within 1 minute is 88. 20 g,and the uranium content is about 59. 64 g. The committed effective dose of internal exposure is 0. 40 mSv. The predicted intake of uranium is4. 57 mg. The average inhalation concentration of HF is calculated to be about 90. 33 mg /m~3,which is below the promptly life-threatening or health-threatening acute concentration( 136. 93 mg /m~3). In this case,it has little impact on human health. If the staffs need 2-4 minutes to evacuate,the leakage amount of UF_6 within 1 minute is 176. 40-352. 80 g,and the uranium content is about 119. 27-238. 54 g,the committed effective dose of internal exposure is 0. 81-1. 62 mSv. In that case,it has a small radiation hazard caused by UF_6. However,the predicted intake of uranium is 9. 26-18. 51 mg,which might lead to a short-term kidney damage. If the evacuation time is 2,3 or 4 minutes,the average inhaled mass concentrations of HF are 83. 98,82. 03 and 81. 03 mg /m~3,respectively,which are close to or higher than the immediately dangerous to life or health concentration( 96. 82,79. 06 and 68. 46 mg /m~3,respectively),and it might lead to an acute HF poisoning,even sudden death. CONCLUSION: When the UF_6 leakage accident happens,the staffs should evacuate in 1minute. If the evacuation time is longer than 2 minutes,it will increase the risk of kidney damage,acute HF poisoning and sudden death.