# Hi every body, i'm working and calculating the keff, and total

by tiepngh
Tags: body, btotal, keff, working
 P: 5 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.
P: 71
 Quote by 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.
Well, you could just take the fuel depletion in atoms...
P: 21,827
 Quote by 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.
Total fission would be the integral of Ʃf and flux ∅(x) over the volume and time. One could reasonably assume a Gaussian pulse and mostly a prompt neutron flux.

P: 5
Hi every body, i'm working and calculating the keff, and total

 Quote by Astronuc Total fission would be the integral of Ʃf and flux ∅(x) over the volume and time. One could reasonably assume a Gaussian pulse and mostly a prompt neutron flux.
and could you show me about Ʃf clearly, eg i want to calculate with thermal neutron(E < 6.625e-7 MeV), and fission cause of U235. how is Ʃf?
Thanks you !
P: 21,827
 Quote by tiepngh thanks for your answer, and could you show me about Ʃf clearly, eg i want to calculate with thermal neutron(E < 6.625e-7 MeV), and fission cause of U235. how is Ʃf? Thanks you !
What is the initial form of the material? Solid metal, ceramic, or a aqueous solution? One can estimate the reactivity from keff-1.

Ʃf = NU235 * σf

and N is the atomic density of the material.
P: 5
 Quote by Astronuc What is the initial form of the material? Solid metal, ceramic, or a aqueous solution? One can estimate the reactivity from keff-1. Ʃf = NU235 * σf and N is the atomic density of the material.
Thanks you very much, i have calculate critical model with solution material, one things i don't know that σf, and could you show me how to find it?
Solution : UO2(NO3)2 . 6 H2O.