Studies On The Analysis Methods Of Radionuclide ^110mAg In Seawater

Under normal operation of nuclear facilities and nuclear accident conditions,gases or liquids containing radioactive substances will be released to the environment in different degrees and affect the marine environment safty.In order to protect the marine ecological environment and conduct the assessment of the marine environment,marine environmental radioactivity monitoring had been widely carried out.^110mAg is one of the important artificial radionuclides,has non-negligible amounts,high accumulation and long biological half-life in marine organisms,which used as a target of marine environmental monitoring.At present,it has been reported that ^110mAg in seawater was enriched by silver chloride precipitation,Ag in seawater was enriched by the lead sulfide co-precipitation,and ^110mAg and ¹³¹I in seawater was enriched by solid silver iodide.In this paper,the analysis methods of ^110mAg in seawater were established by optimizing the enrichment conditions of AgCl precipitation and establishing the methods of PbS co-precipitation and AgI precipitation.At the same time,it tried to extend to the combined analysis of other artificial radionuclides in seawater for providing new technical method of monitoring nuclide in the marine environment and improving the technical level and capabilities of monitoring.The following main conclusions were obtained through laboratory experiments:?1?For the method of silver chloride precipitation,while the pH of seawater is higher than 3,50 mg silver carrier was added to one litre of seawater to form AgCl precipitate,then the AgCl precipitation was centrifuged and determined for ^110mAg using high-purity germanium?spectrometer.The recovery rate of ^110mAg in the whole process is up to 90%,and the radiochemical recovery rate is consistent with the chemical recovery rate.The method of silver chloride precipitation can be used to determine the silver in seawater and was stable for different salinities,different volumes of seawater,and without photopathic operation.?2?For the method of lead sulfide co-precipitation,while the salinity of seawater is higher than 32,20 mg lead carrier was added to one litre seawater,then the sodium sulfide was added according to n(Pb²⁺):n(S^2–)=1:2 to form PbS precipitation.Then the PbS precipitation was ashed and determined for ^110mAg using high-purity germanium?spectrometer.The recovery rate of ^110mAg in the whole process is up to 85%,and the radiochemical recovery rate is consistent with the chemical recovery rate.The method of lead sulfide coprecipitation can be used to determine silver in seawater and was stable for different pH and different volumes of seawater.?3?For the method of silver iodide precipitate,under the conditions of 30 mg silver carrier was added to one litre of seawater and n?Ag⁺?:n?I^–?=1:1,iodide ions and silver carriers are sequentially added to form AgI precipitate.Then the AgI precipitation was centrifuged and determined for ^110mAg using high-purity germanium?spectrometer.The recovery rate of ^110mAg in the whole process is up to 90%,and the radiochemical recovery rate is consistent with the chemical recovery rate.The method of silver iodide precipitation can be used to determine silver in seawater and was stable for different pH,different sanility and different volumes of seawater.Further testing found that silver iodide precipitation method has good recovery rate on the enrichment of ^110mAg and ¹²⁵I while 30 mg silver carrier was added to a litre of seawater and n?Ag⁺?:n?I^–?=1:1.?4?Through the optimization of the three enrichment methods such as silver chloride precipitation,lead sulfide co-precipitation,and silver iodide precipitation,the three methods can be used for enrichment of ^110mAg in seawater.Compared with three enrichment methods of silver chloride precipitation,lead sulfide coprecipitation,silver iodide precipitation,the method of silver chloride precipitation can be the preferred method for the three methods because of the advantages of simpler operation,fewer materials,higher recovery rate.The study also found that the method of silver chloride precipitation only had a good enrichment effect on ^110mAg,the lead sulfide coprecipitation had a good enrichment effect on ^110mAg and ¹⁰⁶Ru,and the silver iodide precipitation only had a good enrichment effect on ^110mAg.In this paper,it also tried to analyze the ^110mAg,⁶⁵Zn,and ⁶⁰Co with the three precipitation methods?AgCl,PbS,AgI?combined with other co-precipitation.The study found that the recovery rate of ^110mAg were affected by co-precipitations and were all about 50%.