Negative Buckling: What Are the Conditions?

[gte116r]

Under what conditions would negative buckling (B^2) be possible?

 

[QuantumPion]

Never. Buckling is a function of physical parameters (sphere radius, reaction cross-sections, diffusion coefficient), none of which can ever be negative.

 

[Nidum]

https://forums.autodesk.com/t5/robo...icients-in-buckling-analysis/m-p/3128634#M573

 

[Astronuc]

https://forums.autodesk.com/t5/robo...icients-in-buckling-analysis/m-p/3128634#M573

Buckling of a structure (mechanical analysis) is not the same as 'buckling' with respect to the neutron flux in a nuclear reactor.

I believe B² < 0 implies the system is subscritical.

Let B² = (νΣ_f - Σ_a)/D = (k_∞ - 1)/L², then the buckling is negative if k_∞ < 1, or Σ_a > νΣ_f.

Ref: http://www.nuceng.ca/br_space/2015-09_4d03_6d03/learning_modules/11_flux_shape_in_various_reactor_geometries.pdf

Geometric buckling would not be negative.