【摘要】 核设施放射性废气组成中含有的放射性核素碘排往环境中可产生安全危害。为在高温条件下对活性炭进行放射性单质碘保留性能测试,依据ASTM D3803-79参数要求,建立了活性炭180℃气流条件下单质碘保留能力测试系统。该系统包括放射性单质碘供料与高温条件单质碘解吸两部分,通过试验验证了系统的密封性能,确定了供料阶段气流流量、放射源131I初始活度范围,并取活性炭样品进行了系统稳定性验证试验。结果表明,该试验系统满足ASTM D3803-79的要求,试验压力下气体泄漏率小,吸附供料所用源初始活度小于0.2 m Ci,载碘气流与稀释气流流量分别为45 L/h与300 L/h。试验结果重现性强、可靠性高,活性炭样品结果标准偏差满足ASTM D4069-81要求。研究表明,该测试系统能对核级活性炭保留放射性单质碘性能进行可靠评价。更多还原

【Abstract】 The paper is intended to present a new testing system developed by its authors for keeping on the capability of the single element iodine with the activated carbon at 180 ℃.As a matter of fact,there remains radioactive iodine in many kinds of radioactive gaseous wastes as a result of production and/or improper causative and consequential process of nuclear facilities,which is necessary for further specific treating,because such remainder is potential to bring about harmful and even poisonous impacts both on the health of the public and the individuals.In particular,we have shown more and more gradual effects of iodine absorber on the retaining of the mere iodine on the accidental conditions.In hoping to make more effective testing of the performance of the remaining radioactive elemental iodine with the activated carbon at high temperatures,we have established a retaining ability testing system of the activated carbon in retaining the radioactive iodine at 180 ℃in accordance with the standard ASTM D3803-79.What is more,the aforementioned testing system also includes a radioactive elemental iodine feeding device and an elemental iodine absorptive tendency.The testing conditions for the desorption phase may include:the gas temperature of(180 ± 3.0) ℃,the gaseous linear velocity of(12.2 ± 0.5) m/min,the absolute gas pressure of(104 ± 5) k Pa,and the gas feeding time of(240 ± 1) min.The testing sequence can be illustrated as follows:it is necessary to learn the sealing performance of the aforementioned system before the test begins;and,then,it is necessary to make sure the gas flux of the feeding phase and the initial radioactivity range before the test,the system stability tests have also to be done with the activated carbon,which is of the same nature with that of being filled into the iodine absorbers.And,next,we have to do the tests on the way for removing the single element iodine with the activated carbon.The results we have done through our tests show that the absorptive system we have developed is in a position to meet the requirements of ASTM D3803-79,with its gas leakage rate being very small at experimental pressure.In addition,the initial radioactivity of iodine source proves to be smaller than 0.2m Ci,with the gas flow rates of iodine-bearing and dilution being45 L/h and 300 L/h,respectively.The testing results have thus been endowed with the perfect repeatability and reliability with its standard errors being low within the range of the limits of ASTM D4069-81.Therefore,the system can be expected to fulfill the function of evaluating its performance of retaining radioactive elemental iodine successfully and satisfactorily.更多还原