Calculating Linear Power in Axial Layers from AFF & RFF

[Syed Alam]

Linear Power calculation in core Axial layers from core average linear power, Axial form factor and Radial form factor:

I want to do coupled neutronic thermal-hydraulic analysis using COBRA and PANTHER.

From PANTHER, we can get Axial form factor (AFF) and Radial form factor (RFF) in each axial layer and radial nodes, respectively for whole-core calculations. In COBRA, we have to put linear power in the each core axial layer as input. An example is given below:0.12 %layer height
5.6774E+03 %Linear Power at height = 0.12 m
0.36
1.6050E+04
0.61
2.3648E+04
0.85
2.7157E+04
1.09
2.5970E+04
1.33
2.0293E+04
1.58
1.1107E+04
1.82
5.6774E+03From PANTHER AFF and RFF values, I want to calculate linear power in each layer of the core for giving input to COBRA.

Can you please check whether my calculation procedure is correct?

Suppose, my core has 10 axial layers.
Core height is 1.82 m.
Average core linear power is 11.3 KW/mSuppose, in axial layer 1 at 0.12 m core height
Axial form factor (AFF) is 1.4
Radial form factor (RFF) is 1.6

Can I say that average linear power in axial layer 1: 11.3*1.4*1.6= 25.312 KW/m?

Can you please correct me if it is not correct with an example calculation?

Thanks in Advance!

 

[QuantumPion]

If you just want the average power for an entire axial level (not just one node), you just multiply the core average by the axial form factor.

Multiplying by both the core average AFF and the core average RFF to determine the power of a particular node at a particular axial level is not accurate as the two peaking factors may not coincide at the same location for a particular node.

 

[QuantumPion]

For example, see this example core with 4 axial levels and 4 assemblies. Using the 2D synthesis does not produce the correct 3D nodal power.

 

[Syed Alam]

If you just want the average power for an entire axial level (not just one node), you just multiply the core average by the axial form factor.

Just to be very much CONFIRM I want you to check this:
Actually I want linear power in each axial layer. so, according to you, I can calculate it by

Linear power at Level 1= 11.3 KW/m*Axial Form factor at level 1
= 11.3KW/m * 1.4 (suppose)
= 15.82 KW/m

And I will repeat this for all the axial level by their respective Axial Form factor.
So, there is no contribution to Radial form factor.

Is it correct??

Thanks Quantumpion!

 

[Syed Alam]

For example, see this example core with 4 levels and 4 nodes. Using the 2D synthesis does not produce the correct 3D nodal power.

I am extremely sorry that I could not follow the figure properly!

1. In the first table, how have you calculated AFF and RPD?

2. How can we calculate 3D RPD for the 3rd table?

Thanks again!

 

[QuantumPion]

No! There indeed is a different radial distribution at each axial level. I'm not familiar with COBRA and PANTHER and I'm not sure what you are trying to do, but you might need full 3D power distribution. You cannot simply combine a 2D axial and 2D radial profile. Well you could, but it would be inaccurate. That is what they did in the old days before computers were powerful enough to actually calculate some things in full 3D.

 

[QuantumPion]

I am extremely sorry that I could not follow the figure properly!

1. In the first table, how have you calculated AFF and RPD?

2. How can we calculate 3D RPD for the 3rd table?

Thanks again!

1) AFF is the ratio of the average of the axial level compared to the core average. RPD is the ratio of the average of the assembly to the core average.
2) 3D RPD is the ratio of the individual 3D node to the core average (note I should have labelled the columns "assembly x" instead of "node x" to avoid confusion).

 

[Syed Alam]

1) AFF is the ratio of the average of the axial level compared to the core average. RPD is the ratio of the average of the assembly to the core average.
2) 3D RPD is the ratio of the individual 3D node to the core average (note I should have labelled the columns "assembly x" instead of "node x" to avoid confusion).

Massive thanks!

 

[Syed Alam]

No! There indeed is a different radial distribution at each axial level. I'm not familiar with COBRA and PANTHER and I'm not sure what you are trying to do, but you might need full 3D power distribution. You cannot simply combine a 2D axial and 2D radial profile. Well you could, but it would be inaccurate. That is what they did in the old days before computers were powerful enough to actually calculate some things in full 3D.

I want to perform Hot channel analysis of my core. It is pretty small. 333 MWth with 1.8 m height and 1.7 m radius. Generally, we have to put "linear power" in each axial layer of the core for COBRA calculation. PANTHER is a 3D whole-core neutronic code from where we can get the power distribution that would be used for hot channel analysis in COBRA.

From PANTHER, we can get Axial form factor (AFF) and Radial form factor (RFF) in each axial layer and radial nodes, respectively for whole-core calculations. In COBRA, we have to put linear power in the each core axial layer as input.

Generally how can I get 3D power distribution? Does 3D power distribution mean "Total Form factor"?

In that case, what parameters do I need for accurate calculation of "linear power" in each axial level? Can you please provide a reference example for this calculation?

I am extremely sorry for asking too many questions! My apology!

 

[QuantumPion]

Sorry I'm not familiar with PANTHER. There should be input options for enabling various output edits, check the manual.

 

[Astronuc]

From PANTHER, we can get Axial form factor (AFF) and Radial form factor (RFF) in each axial layer and radial nodes, respectively for whole-core calculations. In COBRA, we have to put linear power in the each core axial layer as input.

What is the resolution of PANTHER, i.e., does it provide pin-by-pin LHGR. I presume one is using WIMS (9 or 10) for cross-sections.

In some codes, either the axial or radial form factor needs to be renormalized in order to be used with the other form factor to generate the local (pin-based) linear power.

http://www.answerssoftwareservice.com/panther/

In theory, one can obtain support from the PANTHER support team.
http://www.answerssoftwareservice.com/resource/areas/support/helpline.php

One could ask the PANTHER support team about pin/rod power reconstruction. If they provide power histories to ENIGMA, then PANTHER should have pin power reconstruction capability.

According to this paper - http://www.answerssoftwareservice.com/resource/pdfs/139.pdf

Pin power reconstruction is achieved via a two stage process; assembly corner data is interpolated from surface data and then the pin powers are derived within the assembly using the surface and corner data, in conjunction with lattice form factor data.

From the description of the core size, one is describing an SMR. Is it based on PWR technology, and if so, is one using a 17x17 lattice?