What Is Resonance Self-Shielding and Power Share in Nuclear Reactors?

[Syed Alam]

1. What is "Resonance Self-shielding"?
2. What is the "self-shielding of the burnable poison"? How does it help burnable poison not to burnout quickly?
3. I have found that in a paper "POWER SHARE OF THE THORIUM CHAIN" and "The denaturing is necessary in some cases in order to reduce the power peaking in the seed-type fuel by improving the power share of the thorium region at the beginning of fuel irradiation. " What is that Power Share? How is it helpful?

 

[Astronuc]

Resonance shielding refers to the effect of increased neutron absorption in the resonance energy range, such that some fast neutrons do not slow to thermal energies, but are absorbed in the resonance energy range.

Self-shield by enrichment or burnable poisons means that the U-235 or burnable poison toward the interior pellet sees a lower neutron flux than the U-235 or burnable absorber near the surface.

Power sharing refers to power distribution such that peaking is controlled by allowing different regions of the core to produce power. Seed-type fuel is usually in the blanket region or in certain fuel assemblies. Ideally, one tries to reduce peaking in the core so that fuel does not exceed thermal or burnup limits.