The Chernobyl nuclear explosion (in the former Soviet

Chapter 5, Problem 34

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The Chernobyl nuclear explosion (in the former Soviet Union, on April 26, 1986) released large amounts of radioactive substances into the atmosphere. These substances included cesium-137, iodine-131, and strontium-90. Although the radioactive material covered many countries, the actual amount and intensity of the fallout varied greatly from country to country, due to vagaries of the weather and the winds. One area that was particularly hard hit was Lapland, where heavy rainfall occurred just when the Chernobyl cloud was overhead. (a) Many of the pastures in Lapland were contaminated with cesium-137, a radioactive substance with a halflife of 33 years. If the amount of cesium-137 was foundto be ten times the normal level, how long would ittake until the level returned to normal? Hint: LetN0 be the amount that is ten times the normal level.Then you want to find the time when N(t) N0 /10.(b) Follow part (a), but assume that the amount ofcesium-137 was 100 times the normal level.Remark: Several days after the explosion, it was reportedthat the level of cesium-137 in the air overSweden was 10,000 times the normal level. Fortunatelythere was little or no rainfall.