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JAEA-Data/Code 2007-004 - Welcome to Research Group for ...

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5.3 S N Transport Calculation (PIJ, ANISN, TWOTRAN)<br />

The left side figure in Fig.5.3-1 shows a criticality problem of a fuel solution in a cylindrical<br />

stainless-steel container of 0.3cm bot<strong>to</strong>m and side wall thickness, 15cm outer radius and 54.249cm<br />

<strong>to</strong>tal height. This problem is solved by using both of ANISN and TWOTRAN. The calculation scheme<br />

consists of the following three cases.<br />

(1) Production of effective cross-sections by PIJ (case name: CELL)<br />

A fixed source problem is solved <strong>for</strong> a one-dimensional infinitely long cylindrical system of fuel<br />

solution and the container by using PIJ module with 107-group structure. The fine group effective<br />

cross-sections are obtained as the result. This case is <strong>for</strong> the effective resonance calculation by the<br />

PEACO option. If the NR or IR approximation is used, this case is not necessary.<br />

(2) Production of few group cross-sections by ANISN (case name: ANIS)<br />

An eigenvalue is solved <strong>for</strong> the same geometry as that of the first case (the one-dimensional<br />

infinitely long cylindrical system of fuel solution and the container with 107-group structure) by using<br />

ANISN one-dimensional Sn module with P 1 S 8 . In this calculation, the cross-sections are provided by<br />

the first case. The axial leakage is taken in<strong>to</strong> accounted by the transverse buckling. The cross-sections<br />

are collapsed by the flux obtained by ANISN in<strong>to</strong> 18-group structure. To consider the difference of<br />

spectrum of outer part near the vacuum boundary and that of inner part, the cross-sections of fuel<br />

solution corresponding <strong>to</strong> these parts are separately obtained by specifying two homogenization<br />

regions (X-Region).<br />

(3) Few group eigenvalue calculation by TWOPTRAN (case name: TWOC)<br />

The final eigenvalue problem is solved <strong>for</strong> the R-Z geometry by TWOTRAN: two-dimensional<br />

SN module with P 1 S 8 approximation. The 18 group P 0 and P 1 cross-sections <strong>for</strong> three materials (inner<br />

fuel solution, outer one and SS container) are provided by the previous case. The right side figure in<br />

Fig.5.3-1 shows material and zone allocation <strong>for</strong> TWOTRAN.<br />

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