今天发布的“原子能机构报告”认为，日本实验室分析日本福岛第一核电站附近的海水、海洋沉积物和鱼类样品后得出了可靠数据。
今天发布的“原子能机构报告”认为，日本实验室分析日本福岛第一核电站附近的海水、海洋沉积物和鱼类样品后得出了可靠数据。
报告指出：“原子能机构于2014－2016年组织了六次工作组访问之后确认，日本的样品收集程序遵循了获取代表性样品要求的适当方法标准。”报告进一步指出，实验室间比对的结果“证明参与分析海洋区域监测计划海洋样品放射性核素的日本实验室达到了很高的准确度和能力。”
实验室间比对和测试涉及各实验室独立测试和分析样品，以及随后比较结果和程序以确定其可靠性和准确性。7个日本实验室和来自日本以外的3个实验室参与了比较。后者包括摩纳哥的原子能机构环境实验室以及隶属于测量环境放射性分析实验室网络的爱尔兰和新西兰实验室。这些实验室带来了更多国际专门知识，增加了国际透明度。
原子能机构辐射测量实验室负责人Iolanda Osvath说：“98%以上的结果无明显差异，这意味着参与该计划的日本实验室彼此之间及其与其他国家实验室和原子能机构实验室之间表现出了高度的一致性。”
日本政府曾提出援助请求，希望协助其确保福岛第一核电站周边海域的区域监测工作保持高质量、全面性、可信性、透明度。应其请求，原子能机构自2014年起一直与日本实验室合作。该项目是对原子能机构2013年审查日本规划和实施核电站退役工作的福岛第一核电站退役报告提出的海洋监测建议的后续活动。这个项目现在又延长了四年。接下来的步骤将以已完成的工作为基础，会涉及更多实验室间比对和水平测试。
从小名滨卸鱼港收集鱼类样品。（照片来源：原子能机构）
最新成果
去年年底进行的最新实验室间比对包括了海水样品和6批在福岛第一核电站附近捕获的新鲜鱼类。日本化学分析中心、日本地球科学实验室、日本环境综合技术株式会社和原子能机构环境实验室分析了海水样品中的氚（氢-3）、锶-90、铯-134和铯-137。日本御宿町海洋生物环境研究所、日本化学分析中心、日本冷冻食品检查协会和原子能机构环境实验室分析了鱼类样品中的铯-134和铯-137。
检测放射性水平前制备鱼类样品。（照片来源：原子能机构）
在水平测试演习中，原子能机构准备了低放海水测试样品，并要求参与实验室检测其放射性水平。 参与实验室不知道这些所谓“掺料样品”中的放射性水平，向原子能机构报告了其实验方法和结果。全球有50多个实验室参与了这些实验，包括17个日本实验室。迄今为止已发布的该项目水平测试结果发表在原子能机构网站。
为了提高和保持高质量分析能力，原子能机构在世界各地的分析实验室进行了类似演习。
样品分析结果（例）：日本实验室（日本冷冻食品检查协会、日本化学分析中心、海洋生物环境研究所）与原子能机构测量的鱼类样品中铯-137的放射性浓度高度一致。黄色条表示基于四个结果平均值的参考值。所有样品中的铯-137放射性浓度都很低，尤其是样品3和4，经很长时间的测量才能得出结果。
“Over 98% of the results were not significantly different from each other, which means the Japanese laboratories involved in the programme demonstrate a high level of consistency amongst themselves and with laboratories in other countries and the IAEA,” said Iolanda Osvath, Head of the IAEA’s Radiometrics Laboratory.
The IAEA has worked with the Japanese laboratories since 2014, following a request by the Japanese Government to assist it in ensuring that its sea area monitoring around Fukushima Daiichi maintains a high quality, and is comprehensive, credible and transparent. The project is a follow-up activity to recommendations made on marine monitoring in a report by the IAEA in 2013 related to the decommissioning of the Fukushima Daiichi Nuclear Power Station, which reviewed Japan's efforts to plan and implement the decommissioning of the plant.The project has now been extended for another four years. The next steps will build on the already completed work and involve more interlaboratory comparisons and proficiency tests.
Collection of the fish samples from the fish landing port of Onahama. (Photo: IAEA)
Recent results
The most recent interlaboratory comparison performed late last year involved seawater samples and six batches of fresh fish caught near the Fukushima Daiichi Nuclear Power Plant. The seawater samples were analysed for tritium (hydrogen-3), strontium-90, caesium-134 and caesium-137 by the Japan Chemical Analysis Center (JCAC), the Geo Science Laboratory (GSL), Japan, KANSO Co., LTD., Japan and the IAEA Environment Laboratories. The fish samples were analysed for caesium-134 and caesium-137 by the Marine Ecology Research Institute (MERI) in Onjuku, Japan, JCAC, the Japan Frozen Foods Inspection Corporation (JFFIC) and the IAEA Environment Laboratories.
Preparation of the fish samples before measurement of their radioactivity level. (Photo: IAEA)
In the proficiency test exercises, the IAEA prepares test samples of low radioactivity seawater and requires the participating laboratories to measure its level of radioactivity. The amount of radioactivity in these so-called ‘spiked samples’ is not known to the participating laboratories, who report their methods and results to the IAEA. Over 50 laboratories worldwide, including 17 Japanese laboratories, participated in these exercises. Proficiency test results published so far for this project are available on the IAEA website.
The IAEA runs similar exercises for analytical laboratories worldwide in order to improve and maintain high quality analytical capabilities.
Sample analysis results (example): Good agreement is shown between activity concentrations of caesium-137 in fish samples measured by laboratories in Japan (JFFIC, JCAC, MERI) and the IAEA. The yellow bar represents the reference value based on the mean of the four results. Caesium-137 activity concentrations were low in all samples, but particularly in samples 3 and 4 they could only be detected with very long measurement times.