At then end of each minute, record the total counts showing on the detector. Look at the red curve for the fission of 235 U, and you can see the favored mass distribution.
It has a much longer half-life than 131 I and may remain in the environment for many years following a release; it emits characteristic gamma radiation when it decays and is relatively easy to measure. What does nuclear chemistry involve?
You can see from that table that 137 Cs has about a 6. When the 235 U captures a neutron, the excitation energy associated with the capture is sufficient to cause the compound nucleus, 236 U, to break fission into two major fragments, usually accompanied by a few neutrons and some gamma radiation.
It is a concern because when breathed in or ingested it may be taken up by the thyroid gland and produce significant radiation dose to the thyroid. Because the atomic number changes, this is a new element, number 56 , barium, or. A 6 percent yield is a high yield, and 137 Cs is a favored fission product. For your first try, you can ignore any correction for background.
There is much more that could be said about the fission process and the generation and characteristics of the products produced by reactor operations, but I believe the above should be sufficient to answer your questions. The information provided is not a substitute for professional advice and should not be relied upon in the absence of such professional advice.
Join or Renew Members Only. The waste products that accumulate in the reactor fuel are the fission products, with the longer-lived ones, such as 137 Cs, 99 Tc, and 90 Sr, being of most long-term concern. By "favored" I mean those whose fission yields are relatively high.
Be advised that over time, requirements could change, new data could be made available, and Internet links could change, affecting the correctness of the answers. If you make a graph with the horizontal axis being clock time since you start counting, and the vertical axis being the total number of accumulated counts in your counter since you started counting at time "zero", then the vertical axis will show how many 137 Ba decays have been detected plus how many background events have happened.
It happens that in the beta decay of 137 Cs, the product or "daughter" barium nucleus is left in an "excited" state. Good luck.
Answers are the professional opinions of the expert responding to each question; they do not necessarily represent the position of the Health Physics Society. I did come across the actinium series, which I guess is what happens to 235 U in rocks in the Earth's crust undergoing very, very slow decay. As it turns out, if we were to look more closely at just where the 137 Cs is coming from, we would find that most comes from the direct fission of 235 U, and a small amount comes from indirect processes.
Another that you might have heard of is 241 Am, with a 433-year half-life. Related questions What are radioactive isotopes?