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e avoided. Because U08W and U080 are not discriminated in the depletion calculation, use of only
U080 is recommended. It is to be noted that there is no significant effect by chemical binding of UO 2
in usual thermal reactor calculations.
• Plural X-Region specification
When plural X-Regions are specified, one depleting material should not be contained in two
different X-Regions.
• Restart burn-up calculation
The restart burn-up calculation is available as far as members caseHTjj (cf. Sect.3.1) of the
same case name are preserved on MACRO or MACRWRK (no collapsing is done) file. The change of
input data is limited, in principle, only on restart specification and addition of burn-up steps.
Even in the case of abnormal termination due to lack of CPU time or shortage of disk extent, if
the members caseHTjj are preserved on MACRO or MACRWRK file, the calculation can be
continued by using this restart option. However, if the virtual PDS file is used, the members are not
stored in the case of some abnormal terminations. To avoid such a trouble in a large-scale burn-up
calculation, it is recommended to set IOMODE (access mode of MACRO file) to ’File’ (direct file
access) in Block-5 of Sect.2.2.
• Branch-off calculation
The branch-off calculation along the burn-up steps is available if the member caseBNUP of the
reference case is preserved on MACRO or MACROWRK (no collapsing is done) file. The input for
geometry, number of burn-up steps, burn-up intervals, etc. must be consistent with those of the
reference case. Number of materials, the order of materials (=material number) and the burn-up chain
model must be also kept in principle, whereas material temperatures, composition of non-depleting
materials may be replaced.
For example, when the average cross-sections of the assembly with control rod insertion is
obtained by the branch-off calculation, the region in which the control rod is inserted should be
reserved as an R-Region in the reference calculation without control rod insertion.
If the control rod material contains any nuclide which appears in the burn-up chain model, the
material should be specified as non-depleting by using the option IBC10=1.
As coolant water of PWR containing boron circulates in primary circuit, this material should be
treated as non-depleting. The reference burn-up calculation may treat the condition without boron, and
the branch-off calculation treat the condition with boron. In the latter condition, the coolant containing
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