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目的应用NaI(Tl)低本底γ谱仪和高纯锗γ谱仪监测水产品中放射性核素的方法对湛江口岸进出口水产品中的核污染情况进行监测。方法采用3种方法分别得到样品中131I、134Cs、137Cs 3种核素的比活度,并对待测样品进行特定时期监控。方法 1:样品烘干、切片直接进样到Na I(Tl)低本底γ谱仪;方法 2:样品烘干、经微波灰化系统灰化后进样到NaI(Tl)低本底γ谱仪;方法 3:样品烘干、经微波灰化后进样到高纯锗γ谱仪。结果方法 1监测2011~2013年自日本进口的19批水产品,其监测结果均在检测限以下(检测限均为10 Bq/kg);方法 2监测2014年自日本进口5批次水产品,其监测结果均在检测限以下(检测限均为0.5 Bq/kg);方法 3监测2015年进出口水产品共13批次,其监测结果与本底值相当(~(131)I、~(134)Cs、~(137)Cs空白本底值为3 mBq/kg)。结论利用微波灰化进样到高纯锗γ谱仪对水产品3种核素的检测效果最好。通过对湛江口岸近5年来进出口水产品放射性核素的监测分析,尚未发现受放射性核素污染的水产品。
Objective To monitor the nuclear contamination of aquatic products in Zhanjiang port by monitoring the radionuclides in aquatic products by NaI (Tl) low background γ spectrometer and high purity germanium γ spectrometer. Methods The specific activities of 131I, 134Cs and 137Cs in three samples were obtained by three methods, and the samples were monitored for a specific period of time. Method 1: The sample is dried and the slice is directly injected into a Na I (Tl) low background γ spectrometer. Method 2: The sample is dried and ashed after being ashed by the microwave ashing system and infiltrated into a low background γ Spectrometer; Method 3: Sample drying, ashing after microwave sample into the high purity germanium γ spectrometer. Results Method 1 Monitored 19 batches of aquatic products imported from Japan from 2011 to 2013 were monitored below detection limit (detection limit was 10 Bq / kg). Method 2 Monitored 5 batches of aquatic products imported from Japan in 2014, The monitoring results are all below the limit of detection (the detection limit is 0.5 Bq / kg). Method 3 monitors 13 batches of imported and exported aquatic products in 2015, and the monitoring results are comparable to the background values (~ 131 I, ~ 134 ) Cs, ~ (137) Cs blank background value of 3 mBq / kg). Conclusion The microwave ashing sample into the high-purity germanium γ spectrometer has the best detection effect on the three kinds of radionuclides. Through the monitoring and analysis of the radionuclides of import and export aquatic products in Zhanjiang Port over the past 5 years, no aquatic products contaminated by radionuclides have been found yet.