11.9 The Hanford Site, a former plutonium production facility located on the Columbia River in southeastern Washington State, is managed by theU.S. Department of Energy and currently engaged in the

world's largest environmental cleanup project. On site, large tanks of radioactive mixed wastes are stored for eventual disposal. Consider a hypothetical situation in which Cesium-137, a radioactive compound with a half-life much longer than 10 years, is accidentally released to the Columbia River (approximate flow 4000 m3/s), with the concentration profile drawn below being observed at Bonneville Dam, approximately 400 km downstream. (a) Determine for this hypothetical how many radioactive units of this tracer would have been accidentally released. (b) Determine the volume of the Columbia River between Bonneville Dam and the Hanford Site.