Coolant Mass Flow Rate Through Subchannel in Nuclear Fuel Assembly

AI Thread Summary
To find the mass flow rate of coolant through a channel in a hexagonal nuclear fuel assembly, it is essential to calculate the power associated with one coolant channel, or "unit cell." The total power produced by a fuel pin cannot be directly applied to a single coolant channel due to lateral power gradients and the influence of neighboring fuel rods. When modeling a hexagonal lattice, a triangular control volume can be used, incorporating 1/6 of a fuel rod at each vertex. Additionally, the presence of control rod guide tubes can complicate the analysis, as they affect the power distribution among adjacent fuel rods. Understanding these factors is crucial for accurately determining the heat transfer characteristics within the assembly.
a1234
Messages
78
Reaction score
6
I am trying to find the mass flow rate of coolant through a channel within a hexagonal nuclear fuel assembly. I am given the specific heat of the fluid, the coolant inlet and outlet temperatures, the total power produced by a single fuel pin, the diameter of the fuel pin, the length of the fuel pin, and the fuel pitch. I am told that the power follows a cosine shape axially.

I am trying to incorporate this information into q = m*cp*deltaT, but the power "seen" by one coolant channel is not the same as the total power produced by one pin. How can I find the power that is part of one coolant channel (or one "unit cell") within a hexagonal assembly using the given information?
 
Engineering news on Phys.org
We, if the fuel rods have the same enrichment and neutron flux, then the power, or heat flux, would be the same at the same axial elevation. On the other hand, fuel assemblies can have substantial flux/power gradients laterally across a given axial elevation.

If one is modeling a hexagonal lattice, then one can look at a triangular control volume with 1/6 of a fuel rods at each vertex of the cell. Otherwise, one observes 6 subchannels around a given rod, not on the boundary (outside row) of the lattice/assembly.

If one has control rod guide tubes in the lattice, e.g., in VVER-1200 fuel assembly, then that is also a special case.

The guide tube issue is encountered in PWRs, e.g., in a 17x17 where most fuel rods are next to at least on guide tube, and some fuel rods are next to two guide tubes.
 
  • Like
  • Informative
Likes Alex A and a1234
Hello everyone, I am currently working on a burnup calculation for a fuel assembly with repeated geometric structures using MCNP6. I have defined two materials (Material 1 and Material 2) which are actually the same material but located in different positions. However, after running the calculation with the BURN card, I am encountering an issue where all burnup information(power fraction(Initial input is 1,but output file is 0), burnup, mass, etc.) for Material 2 is zero, while Material 1...
Hi everyone, I'm a complete beginner with MCNP and trying to learn how to perform burnup calculations. Right now, I'm feeling a bit lost and not sure where to start. I found the OECD-NEA Burnup Credit Calculational Criticality Benchmark (Phase I-B) and was wondering if anyone has worked through this specific benchmark using MCNP6? If so, would you be willing to share your MCNP input file for it? Seeing an actual working example would be incredibly helpful for my learning. I'd be really...

Similar threads

Replies
1
Views
2K
Replies
1
Views
1K
Replies
8
Views
3K
Replies
3
Views
3K
Replies
6
Views
2K
Replies
10
Views
3K
Back
Top