Sg. Hong et Nz. Cho, CRX - A CODE FOR RECTANGULAR AND HEXAGONAL LATTICES BASED ON THE METHOD OF CHARACTERISTICS, Annals of nuclear energy, 25(8), 1998, pp. 547-565
A transport theory code CRX based on the method of characteristics wit
h a general geometric tracking routine for rectangular and hexagonal g
eometrical problems is developed and tested for heterogeneous cell and
assembly calculations. Since the method of characteristics uses the c
haracteristic form of the Bolzmann transport equation, CRX has no prac
tical limitations placed on the geometry of the problem and gives accu
rate solutions in strongly absorbing media. To relax the constraints o
f the existing charateristic transport calculation codes, a new, treat
ment of the reflective condition is introduced. In this treatment, the
external reflective boundary is discretized into small segments and t
he angular fluxes for rays along a segment are assumed to be uniform.
Also, a new calculational procedure for condensation is devised to obt
ain an accurate energy spectrum of absorber cells. after the character
istic cell calculation, an S-N transport calculation is performed for
the assembly comprised of homogenized cells. The result is used to cal
culate group and angular octant dependent albedos on absorber cell bou
ndaries. Then, the two-dimensional characteristic transport calculatio
n with the albedo boundary conditions is performed again for absorber
cells. Using the condensed group macroscopic cross sections, a two-dim
ensional characteristic transport calculation is performed for the het
erogeneous assembly. To test the code, it is applied to several benchm
ark problems which consist of complex meshes and compared with other c
odes. The results show that the CRX code is very accurate. (C) 1998 El
sevier Science Ltd.