Wanda Code

Graphs are provided in Figures 7, 8, and 9 corresponding to three values of ASp. In each case there is exhibited the steady state flux, some of the transient fluxes, and the asymptotic flux, all normalized to equal areas. Also provided is the stabilization time for each case, that is, the total time elapsed in attainment of the asymptotic shape. The criterion used to specify a stabilization time is discussed at the end of this section. The step changes in reactivity exhibited in the three figures were computed by a conventional steady state two-group criticality calculation with the aid of the Wanda Code (IBM-704) [19]. For the calculations under discussion = A eff — 1-... 

Figube 10. Comparison of results achieved with harmonics method and Wanda Code. Curve 1 is steady state thermal flux. Curve 2 is asymptotic flux distribution for harmonics method. Curve 3 is asymptotic flux for Wanda Code (time-independent). 

The analytic study was di ded into three phases. In the first phase, homogeneous two-region, systems were examined using the diffusion theory WANDA Code. The configuration studied consisted of a spherical core surrounded by a homogeneous miJ reof natural uranium and HiO. The H-to- U ratio was varied in the central core and reflector region. The results indicate a minimum critical mass of 451 g U occurs for a H/ U equal to 450 in both regions. ... 

O. R. Marlowe et al., Wanda—one-dimensional few group diffusion equation code for the IBM-704, WAPD-TM-28, 1957. 

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