hi every body, i'm working and calculating the keff, and [B]total

tiepngh

hi every body, i'm working and calculating the keff, and total fission produced in critical accident in the cylindrical model. If critical mass is roached.
I calculated variable multiply coefficient (keff) by MCNP 5.
also total fission produced i don't know how to calculate this variable,
I really need your help.
thanks you very much for your help.

wizwom

Well, you could just take the fuel depletion in atoms...

Astronuc

Total fission would be the integral of Ʃ_f and flux ∅(x) over the volume and time. One could reasonably assume a Gaussian pulse and mostly a prompt neutron flux.

tiepngh

thanks for your answer,
and could you show me about Ʃ_f clearly, eg i want to calculate with thermal neutron(E < 6.625e-7 MeV), and fission cause of U235. how is Ʃ_f?
Thanks you !

Astronuc

What is the initial form of the material? Solid metal, ceramic, or a aqueous solution? One can estimate the reactivity from k_eff-1.

Ʃ_f = N_U235 * σ_f

and N is the atomic density of the material.

tiepngh

Thanks you very much, i have calculate critical model with solution material, one things i don't know that σ_f, and could you show me how to find it?
Solution : UO2(NO3)2 . 6 H2O.

Astronuc

I would expect it is in a library of cross-sections in MCNP 5.

Otherwise, http://www.nndc.bnl.gov/sigma/index....dfb7.1&nsub=10 - and find (n,total fission).

There will be no delayed neutrons.

tiepngh

Many thanks, and i will try to finish my problem....thanks again!