Question 15 Why are spent fuel rods highly radioactive? What does a cancer slope
ID: 1710523 • Letter: Q
Question
Question 15
Why are spent fuel rods highly radioactive? What does a cancer slope factor represent? 20 additional cancers were observed over course of peoples' lifetime in a population of 10 million. What is the ILCR for that cancer? Is cancer a "chronic" disease outcome, or an "acute" disease outcome, and why? If the ILCR exactly doubles as the dose doubles, does this mean the toxicology model is near no threshold" or "linear with threshold". Why? The dose of carcinogen A to a population is is 1 mg/kg-day. The cancer slope factor is 0.0005 (mg/kg-day) What is the ILCR? Is the above ILCR considered a generally acceptable level of risk? Why/Why not? For the preceding problem, if the population size is 500,000, how many additional cancers will there be over the course of the lifetimes of the people in that population? If you took a million people and bruised their hand each in exactly the same way, is it possible that you would induce a few cases of some kind of cancer by so doing? Why/why not. Let's say you are reading about a study of the effects of hexavalent chromium on the organism daphnia, where the study was exposing the organisms to 1 mg/L for 3 days and observing their ability to swim. Are you reading about a chronic endpoint or an acute endpoint?Explanation / Answer
15)
First, lets understand some background on how nuclear power plant work.
The fuel in reactor contains material that can undergo nuclear fission.
Most of the fuel starts out as uranium material like uranium oxide that's pressed into little pellets. It's kind of like pottery, and you put it into long metal tubes, which are sealed, and those tubes are called fuel rods.
In a fission reaction, a uranium atom splits apart, that release a lot of energy in the process. That energy, in the form of heat powers the turbines that makes the electricity. But as the fission reaction proceeds, the uranium fuel gets used up. A timecome when the fuel becomes inefficient.
When that happens, plant operators use control rods to turn off the fission reaction, and then they take the spent fuel rod out of the reactor. When the fuel rods come out they are hot. But the heat is not just lingering heat from the fission reaction. These are radioisotopes that come from the products of the fission. These fission byproducts (in fuel rods) are thus very radioactive, but they're not permanently radioactive.
The radioactivity drops very dramatically over the first couple of days, and then it goes down by a factor of a hundred over the next several years. To cool the fuel rods that have come out of a reactor, they're submerged in water which is called as a spent fuel pool. The water does two things — the water provides cooling, and it also provides radiation shielding.