Cesium-137


The Diablo Canyon Power Plant runs on nuclear fuel, predominantly Uranium-235When the unstable 
nuclei of these ato
ms are hit by a slow-moving neutron, they split, creating two daughter nuclei and two or three more neutrons. These neutrons then go on to split more nuclei. This creates a self-sustaining chain reaction that is controlled in a nuclear reactor, or uncontrolled in a nuclear weapon.

The energy of these reactions is transferred to water, and used to generate electricity, as seen in the diagram below (as seen in the Harris plant in North Carolina)



One of the byproducts of this Uranium-235 fission is Cesium-137. Cesium 137 is the most worrisome isotope in accidents or acts of malice for several reasons:

  • Cesium 137 is a strong gamma ray emitter.
  • In 10 year old spent fuel, cesium 137 contributes 21% to the total amount of radioactivity, more than any other radioisotope in High Level Radioactive Waste.
  • Cesium 137 assumes the consistency of talcum powder in fires, i.e. it is easily carried off by wind currents.
  • Much of the off-site contamination at Chernobyl was due to cesium 137, rendering a 12,400 square mile area as uninhabitable for decades (SLO County has 3,307 square miles).
Cesium-137 is considered dangerous for up to 10 half-lives (called a "Hazardous Life"). It can take a long time for this product to become non-hazardous, as seen in our graph below...

 My Half-Life Graph (5 pts)

Using your data from lab 6, make a graph of half-life depletion of Cesium-137. Each trial will represent a single half life (30 years for Cesium). Include the following:

1) Data for graph
2) Title for graph
3) Correct labels for x/y axis
4) Correct years for half life (x-axis)
5) Correct trend line for graph (exponential!)



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