Don’t pick up, disassemble, or sell unidentified metal parts; stay clear of areas marked with the clover symbol

No cost involved. If you see unfamiliar metal cylinders, lead containers, or parts removed from equipment, simply steer clear — don’t pick them up, take them apart, or put them in your pocket.

China’s National Nuclear Safety Administration explains that radioactive sources are solid radioactive materials permanently sealed in containers or having tight encapsulation. Industrial level gauges, flaw detectors, and gamma knives used in hospitals all use this type. Without protection, contact with Class III radioactive sources can cause permanent damage within a few hours and death within days to weeks. X-rays are invisible to the naked eye; gamma rays are also electromagnetic waves, just like them. Preventing external exposure relies on three things: shortening time, increasing distance, and adding shielding. Gamma rays have strong penetrating power; only thick concrete walls or lead can block them. As of 2025, there are approximately 178,000 radioactive sources in use and 355,000 (sets of) radiation devices nationwide in China. The annual occurrence rate of radioactive source radiation accidents remains stable at less than 1 per ten thousand sources. The classification is as follows: the loss, theft, or loss of control of Class I and Class II radioactive sources constitutes a major radiation accident. Class III constitutes a significant radiation accident (较大). The loss or theft of Class IV and Class V sources, or personnel exposure above annual dose limits, constitutes a general radiation accident. Official case: In June 2020, at a blast furnace pipeline renovation project of the Ningxia Iron and Steel Group, gamma-ray flaw detection work was being performed. A Class II Iridium-192 radioactive source caused three workers to be exposed. Chen XX suffered Grade III acute radioactive skin injury on the left hand. Liu XX suffered Grade IV injury to the left thumb and index finger, and Grade III injury to the middle, ring, and little fingers. Fan XX suffered Grade I-II injury on the left hand. The radiation doses received by all three individuals severely exceeded the dose limits prescribed by national standards, and the two responsible units had their radiation safety licenses revoked and were fined 70,000 yuan. International case: In 1987, in Goiânia, Brazil, a teletherapy machine from an abandoned clinic was dismantled. A 50.8 TBq Cesium-137 radioactive source inside was removed, and the source capsule was also punctured. Approximately 112,000 people underwent monitoring. Among them, 249 people suffered internal or external contamination. Of these 249 people, 129 had moderate to severe contamination, and 50 required close medical supervision. Finally, 4 people died (National / International).

生态环境部 (2025). 2024 中国生态环境状况公报. https://www.mee.gov.cn/ywgz/sthjjcgl/hjzljcypj/202506/t20250605_1120773.shtml；国家核安全局 (2026). 2025 年我国核与辐射安全监管工作成效. https://nnsa.mee.gov.cn/tpxw/202601/t20260107_1140062.html；生态环境部 (2021). 关于一起 γ 射线探伤作业违法违规造成辐射事故案件处理情况的通报. https://www.mee.gov.cn/xxgk2018/xxgk/xxgk06/202101/t20210121_818216.html；国务院 (2019). 放射性同位素与射线装置安全和防护条例（2019 年修订，第三十四、四十二、六十八条）. https://www.mee.gov.cn/ywgz/fgbz/xzfg/201909/t20190918_734315.shtml；环境保护部 (2009). 关于建立放射性同位素与射线装置辐射事故分级处理和报告制度的通知（辐射事故分级标准）. https://www.mee.gov.cn/gkml/zj/wj/200910/t20091022_172414.htm；国家核安全局. [核技术利用]什么是放射源?：「放射源，是指除研究堆和动力堆核燃料循环范畴的材料以外，永久密封在容器中或者有严密包层并呈固态的放射性材料」「如料位计、伽玛探伤机等使用的都是密封源」，Ⅲ类放射源「在没有防护情况下，接触这类源几小时就可对人造成永久性损伤，接触几天至几周也可致人死亡」. https://nnsa.mee.gov.cn/ztzl/haqshmhsh/hyfsaqkp/kptw/202406/t20240624_1076670.html；国家核安全局（转载山东环境核与辐射处）. 核与辐射科普知识：「工业料位计使用的铯-137、探伤机使用的铱-192及医院伽马刀使用的钴-60等」. https://nnsa.mee.gov.cn/ztzl/haqshmhsh/hyfsaqkp/kptw/202406/t20240624_1076991.html；国家核安全局. 神奇的核技术（十六）——辐射的防护与管理：「对于外照射的基本防护措施一般有三种方法：时间防护、距离防护和屏蔽防护」. https://nnsa.mee.gov.cn/ztzl/haqshmhsh/hyfsaqkp/kptw/202406/t20240624_1076933.html；国家核安全局. [辐射防护]辐射的种类有哪些？：「γ射线和X射线一样，都是电磁波」「穿透能力较强，需要较厚的物质才能屏蔽，多采用厚混凝土墙或铅等物质防护」. https://nnsa.mee.gov.cn/ztzl/haqshmhsh/hyfsaqkp/kptw/202406/t20240624_1076595.html；国家核安全局. 生活中的核知识——X射线安检机：「X射线又称伦琴射线，它是肉眼看不见的一种射线」. https://nnsa.mee.gov.cn/ztzl/haqshmhsh/hyfsaqkp/kptw/202406/t20240624_1076874.html；湖南省地质院 (2023). 核技术利用之射线装置（摘自《核安全综合知识辅导读本》）：「X射线机的核心部分是X线管」「缓发辐射在加速器停机后仍然存在」「加速器停机后，进入加速厅或靶厅时要考虑感生放射性的影响」. http://hnsdzy.hunan.gov.cn/dzy/c101626/c101627/c101633/202304/t20230411_29311495.html；International Atomic Energy Agency (1988). The Radiological Accident in Goiânia. IAEA, Vienna. https://www-pub.iaea.org/MTCD/Publications/PDF/Pub815_web.pdf；王福如, 王进, 余宁乐, 等 (2019). 南京“5.7”放射源丢失事故受照者照后医学随访观察. 中华放射医学与防护杂志, 39(11), 859-863. https://doi.org/10.3760/cma.j.issn.0254-5098.2019.11.011；中国环境报 (2014-05-15). 放射源丢失的48小时（徐小怗、邵艺、褚方樵、汤景茹）. http://nnsa.mee.gov.cn/ztzl/haqshmhsh/hjbzl/202406/P020240624472937009953.pdf（网页存档 https://web.archive.org/web/20261005044102/http://nnsa.mee.gov.cn/ztzl/haqshmhsh/hjbzl/202406/P020240624472937009953.pdf）

If you encounter one, move away, remember the location, do not move it, and call 110 in China. The regulations require reporting to environmental, public security and health authorities. An ordinary person’s precautions are to keep their distance and spend less time nearby; pockets and plastic bags do not block gamma rays. X-ray machines and CT scanners generate radiation by powering an X-ray tube and do not themselves contain radioactive sources; this is an inference from how the equipment works. Accelerators are different: induced radioactivity remains in structural materials and room air after shutdown. The real danger is the sealed radioactive source inside equipment such as Gamma Knife systems, gamma industrial radiography units and level gauges. In the Goiânia accident, people dismantled a machine and removed its source. Do not expect to recognize a source: never dismantle, sell or take home equipment parts of unknown origin. China has also had cases of people unknowingly picking up radioactive sources. In May 2014, an iridium-192 source was lost during industrial radiography at a factory in Nanjing Chemical Industry Park. A warehouse manager picked it up during an inspection and put it in his work-clothes pocket. He was later diagnosed with mild acute radiation sickness and acute radiation skin injury to his right leg, spent a year in hospital and still needed two crutches years later. Two other workers said they had seen it; one thought it was a necklace on his way to work, picked it up to look and threw it away. The company that lost it was Tianjin Hongdi Engineering Testing Development Co., Ltd. No official accident bulletin was found. The finder’s injuries come from a follow-up paper by a Jiangsu CDC doctor; the account of picking it up and discarding it appears only in a China Environment News report. People working in scrap recycling, dismantling, hardware and construction are more likely to encounter such sources; this is an inference from the Goiânia and Nanjing accidents. Avoid construction-site exclusion zones marked with the radiation trefoil. This item concerns uncontrolled radioactive sources; nuclear power plant leaks are a different type of accident and are not covered here. The main beneficiaries are you and family members at the scene.