Understanding Nuclear Core: Fuel Rod Composition and Control Rod Function

In summary: The pellets are made of a mixture of uranium dioxide and zirconium oxide. Zirconium oxide has a very high melting point and is not affected by water, which is why it is used in fuel rods.
  • #1
biferi
191
0
I know the Fuel Rods are 12 Feet long Tubes made of Zirconium Alloy.

And they fill them with Uranium Oxide Pellets.

And the Control Rods are inserted inbetween them to slow down the reaction.
And the Control Rods are made of Boron.

But is the Control Rods Tubes filled with Boron Pelletes or are the Control Rods just Solid Tubes made of Boron?
 
Engineering news on Phys.org
  • #2
It looks like the rods are solid material.
from:
http://en.wikipedia.org/wiki/Control_rod

Boron is another common neutron absorber. Due to different cross sections of 10B and 11B, boron containing materials enriched in 10B by isotopic separation are frequently used. The wide absorption spectrum of boron makes it suitable also as a neutron shield. Mechanical properties of boron in its elementary form are unfavourable, therefore alloys or compounds have to be used instead. Common choices are high-boron steel and boron carbide. Boron carbide is used as a control rod material in both pressurized water reactors and boiling water reactors.
 
  • #3
biferi said:
I know the Fuel Rods are 12 Feet long Tubes made of Zirconium Alloy.

And they fill them with Uranium Oxide Pellets.

And the Control Rods are inserted inbetween them to slow down the reaction.
And the Control Rods are made of Boron.

But is the Control Rods Tubes filled with Boron Pelletes or are the Control Rods just Solid Tubes made of Boron?
Most PWR fuel rods have an active fuel (e.g., ceramic UO2 pellets) of 12 ft. The cladding tubes are slightly longer in order to provide a plenum or open volume to accommodate fission gas released during operation, and to accumulate the He fill gas as the cladding creeps down on the fuel and as the fuel swells during operation.

Some PWRs have longer fuel rods, e.g., 12.5 ft active fuel or 14 ft active fuel. BWR fuel rods may have fuel zones of 12.2 to 12.5 inches, and some BWR fuel assemblies incorporate shorter or part-length fuel rods.

PWR control elements are comprised of stainless steel (304L or 316L) tubes which are suspended from a steel hub and spider. The tubes slide along the guide tubes in the assembly. Each tube is seal-welded with stainless steel endplugs, and the upper endplug shank is then attached to the spider-hub assembly. The absorber material within the tubes is in solid form, which could be pellet of B4C (with the B enriched in B-10), silver-indium-cadmium (AIG), Hf or Hf-alloy, or Dy titanate. Dy titanate has been developed in Russia and is relatively new. AIG is the most common absorber in PWR fuel. Hf was used for a while, but the Hf absorbs hydrogen which comes from the coolant and over time, the Hf swells with the accumulation of H.

BWR control blades have a cruciform structure and actually sit between fuel assemblies rather than within an assembly. The absorber material is either B4C or Hf, or a combination.
 
  • #4
The control rods are solid tubes with material on the inside. I don't know if it is pellets or what not, I do know that if we crack a rod it will leak all cycle and is pretty messy to deal with from both a water chemistry and reactivity perspective.
 
  • #5
For metals like silver-indium-cadmium alloy or Hf, the absorber is in the form of a cylindrical bar or rod. It may be hollow. Ceramics such as B4C are in the form of pellets or slugs.
 

What is the purpose of a nuclear fuel rod?

A nuclear fuel rod is a long, slender tube that contains uranium pellets. Its purpose is to provide fuel for a nuclear reactor, which undergoes a controlled nuclear fission reaction to produce energy.

What is the composition of a nuclear fuel rod?

A nuclear fuel rod is typically made up of a zirconium alloy cladding and uranium pellets. The cladding helps to contain the radioactive materials and prevent them from escaping into the environment.

How do nuclear control rods function?

Nuclear control rods are made of a material, such as boron or cadmium, that can absorb neutrons. By inserting or removing these control rods into the reactor, the rate of the nuclear reaction can be controlled. When the control rods are inserted, they absorb neutrons and slow down or stop the reaction. When they are removed, the reaction speeds up.

Why is it important to control the nuclear reaction in a nuclear core?

A nuclear reaction in a nuclear core can produce an enormous amount of energy, but it must be carefully controlled to prevent it from becoming uncontrollable and leading to a meltdown. Controlling the reaction also helps to regulate the amount of heat produced, which is crucial for generating electricity.

What safety measures are in place for nuclear reactors?

Nuclear reactors have several safety measures in place, including redundant systems to prevent accidents and backup cooling systems to prevent overheating. They also have strict regulations and protocols for operation and maintenance, as well as emergency response plans in case of accidents or malfunctions.

Similar threads

  • Nuclear Engineering
Replies
25
Views
5K
  • Nuclear Engineering
Replies
2
Views
1K
  • Nuclear Engineering
Replies
25
Views
6K
  • Nuclear Engineering
Replies
6
Views
4K
Replies
36
Views
5K
  • Other Physics Topics
Replies
4
Views
1K
  • Nuclear Engineering
Replies
2
Views
2K
  • Nuclear Engineering
Replies
2
Views
1K
  • Introductory Physics Homework Help
2
Replies
47
Views
3K
Replies
19
Views
7K
Back
Top