Talk:Control rod

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WikiProject Physics (Rated C-class, Mid-importance)
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Merge[edit]

It was suggested by User:Christopher Thomas that this article be merged into nuclear reactor. Having looked at both articles I don't think this is nessecery so I have removed the template - this does not meen that the same sugestion can not be made later, or indeed the merge made without discussion. Andreww 07:23, 16 October 2005 (UTC)

I also think it shouldn't be merged. I think it would be cool though if we could make a template and a series of parts of nuclear plants. I'll write some if people want me to :) theanphibian 14:56, 27 April 2007 (UTC)
What about 'carbon rods' ? I've heard about these and you put them in reactors to stop the fission.. but the list of elements that a control rod can be made of doesn't seem to include carbon.
Control rods typically use Boron-carbide or Hafnium, both of which have strong neutron-absorbing qualities ("large thermal cross-sections"). Hafnium, while expensive, is used in the top parts of BWR control rods (actually, in BWRs, cruciform blades) for its very long life, thus reducing time spent replacing worn-out control rods. Simesa 06:13, 11 August 2007 (UTC)

Carbon is not used in control rods because it is not a neutron absorber. (small cross section for absorbtion). It is used in some reactors as a moderator (graphite moderated reactors, like Chernobyl for instance) because it does not absorb neutrons, but moderates them to allow them to reach the energy level which will let them cause a fission in the Uranium. Moderating is done by neutrons bouncing off of the neucleus of the carbon atom giving up some of their energy in the collision. —Preceding unsigned comment added by 75.68.15.249 (talk) 14:57, 8 March 2008 (UTC)

And I believe the Chernobyl control rods were poison rods with graphite moderator ends. The point, I believe, was to increase the reactivity change per inch of control rod movement. Because the control rods had been pulled further out of the core than they were supposed to be, these moderator tips were out of the main flux when the accident began and created additional reactivity when they fell back down into the core - even though lowering these rods was supposed to reduce reactivity under normal circumstances. I don't know if other reactors use this design or if there are such things as moderator control rods, but it seems worth mentioning. Mishlai (talk) 11:09, 25 September 2008 (UTC)

Dysprosium reference[edit]

The reference for this material is a web forum. It appears to be a reputable post, and the post also provides a citation:

Journal of Nuclear Materials Vol: 281, Issue: 1, September 2, 2000 pp.84-89

but it would still be nice to have a reference that wasn't a forum post. Does anyone have access to this issue of Journal of Nuclear Materials? Mishlai (talk) 11:28, 25 September 2008 (UTC)

Where is the BWR love?[edit]

I realize that this is pretty much the Wikipedia article that covers the entire topic of "things we stick into a nuclear reactor to reduce reactivity". That makes it a little difficult to have a conversation with someone about cruciform blades. One would think that it would make most sense to generalize this to cover all types of this. -Theanphibian (talkcontribs) 22:14, 20 March 2011 (UTC)