8. In 1986, an accident at the Chernobyl nuclear power reactor led to widespread

contamination of Cesium-137, a highly radioactive, man-made isotope of Cesium. It has a

half-life of 30.17 years, which means it decays at a rate of 2.3% per year. It is estimated

that nearly 191,500 kBq/m² was leaked during the disaster. How much of the material is

still radioactive now, 25 years later?