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Six group point kinetic equation

  1. May 18, 2007 #1

    I would be very thankful with some help with the numerical solution of the six group point kinetic equations, with the constant reactivity (step change).

    I would like to do this with the Mathematica.


    Best regards, Dusan
  2. jcsd
  3. May 20, 2007 #2
    Does anyone have any experience with numerical solution of the 6 group point kinetic equation, with the step reactivity change?


  4. May 21, 2007 #3


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    Staff: Mentor

    Dose the solution involve one-group diffusion with 6 delayed groups, so that one is solving the one group neutron diffusion equation and 6 equations for each group of precursors? Presumably the reactivity is between 0 and beta?

    I've solved the inhour equation and one group w/ one delyed, but that was 25 years ago, so I may be slow on this.

    What equations are you using?
  5. May 21, 2007 #4

    I am trying to solve the following 7 equations:
    dn(t)/dt=ρ-β/l n(t)+∑6i=1 λiCi+Q0/l

    dCi(t)/dt= βi* n(t)/l- λiCi.

    Where Q0 is constant extra source with neutrons per second.

    Lets say that I have the subcritical reactor with the reactivity ρ=-0.0526, which corresponds to k=0,95 (multiplication factor).

    Now I increase the reactivity to ρ=-0.04167 (step reactivity change), which corresponds to k=0,96.

    What is the n(t) in 6 group approximation.

    I already made the analytical solution with one group approximation and now I am trying to find the numerical six group solution. Most probably I will do this with Runge-Kutta method. I just wanted to ask if there is someone with any experiences?

  6. May 21, 2007 #5


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    Staff: Mentor

    Runge-Kutta is the standard approach to solving these couple diff EQs.
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