- #1
girts
- 186
- 22
Just a quick question I got in my mind while reading up about fission, the so called Doppler effect which manifests itself in fertile material like U238, I read it helps control reactor stability , hence the majority of fuel consists of U238, as the fuel heats up at some point, U238 starts to absorb more neutrons and hence less neutrons are available for fission which decreases the further rise of reactivity,
now firstly I assume this is a natural physical phenomenon that just so happens to serve in our favor in a reactor core?
secondly tell me please what exactly is the "magic" trick here, is it that while the temperature is lower in the fuel the nucleus of U 238 has lower motion and hence a smaller cross section so only neutrons of specific energy get absorbed while others are not and when the temp rises the target nucleus kind of "moves" more and hence it somehow can accept a wider range of neutrons energies and absorb them?
now firstly I assume this is a natural physical phenomenon that just so happens to serve in our favor in a reactor core?
secondly tell me please what exactly is the "magic" trick here, is it that while the temperature is lower in the fuel the nucleus of U 238 has lower motion and hence a smaller cross section so only neutrons of specific energy get absorbed while others are not and when the temp rises the target nucleus kind of "moves" more and hence it somehow can accept a wider range of neutrons energies and absorb them?