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

1. Mar 5, 2012

### tiepngh

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

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,
thanks you very much for your help.

2. Mar 6, 2012

### wizwom

Re: Tokai-mura(jco)

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

3. Mar 6, 2012

### Staff: Mentor

Re: Tokai-mura(jco)

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.

4. Mar 21, 2012

### tiepngh

Re: Tokai-mura(jco)

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 !

5. Mar 22, 2012

### Staff: Mentor

Re: Tokai-mura(jco)

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.

6. Mar 26, 2012

### tiepngh

Re: Tokai-mura(jco)

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.

7. Mar 27, 2012

### Staff: Mentor

Re: Tokai-mura(jco)

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

Otherwise, http://www.nndc.bnl.gov/sigma/index.jsp?as=235&lib=endfb7.1&nsub=10 - and find (n,total fission).

There will be no delayed neutrons.

8. Mar 30, 2012