# Keyword:PATH

This keyword allows a particular pathway consisting of nlink reactions and decays to be specified. The (nlink+1) nuclides in the pathway are input using their identifiers (e.g. ‘Te129m’). For backwards compatibility the ‘R’ and ‘D’ have been retained, but are not used. Any character (e.g., ‘X’) could be used instead. All reactions and decays between a given parent and daughter nuclide are retained, and the path calculation gives a breakdown of the percentage of the inventory of the daughter due to each reaction and decay that leads to it from the specified parent.

This keyword is necessary only if a special investigation of pathway information is needed. Pathway data can be generated automatically for all the dominant nuclides by using the UNCERTAINTY keyword. PATH might be used for a particularly complicated pathway not generated automatically or to investigate nuclides only formed in small amounts.

Path inventories are calculated over all the timesteps until the ZERO keyword is encountered.

It is possible when using this keyword to produce first a standard inventory and then the numbers of atoms of the daughters are specified in subsequent runs using the RESULT keyword. No inventory then needs to be calculated for these runs investigating the pathways.

Example usage:

< -- Control phase -- >
...
CUMFYLD
FISPACT
* Title of the simulation
< -- Initial phase -- >
...
PATH 3
Ti46 R Ti45 D Sc45 R Sc44m
...
< -- Inventory phase -- >
...


which searches for this particular path in the production of Sc44m, producing an output such as:

...
Target nuclide Sc 44m 5.060% of inventory given by 1 path
--------------------

path 1 5.060% Ti 46 ---(R)--- Ti 45 ---(b)--- Sc 45 ---(R)--- Sc 44m---(S)---
100.00%(n,2n) 100.00%(b+) 100.00%(n,2n)
0.00%(n,p)
...


which indicates that 5.060% of the daughter Sc44m was produced through this path. Note that the very small entries, such as the 0.00%(n,p) indicate a <0.005% (with default settings) contribution from the (n,p) instead of the beta+ decay.