Keyword:SSFMASS

SSFMASS totm indx2
sym(i) xp(i) i=1,indx2

---

This keyword allows the input of the total mass totm (kg) and the number (indx2) of elements in the material to be used in the self-shielding calculation. For each element the chemical symbol sym(i), e.g. W, and the percentage by weight, xp(i), are then read. This keyword enables elements to be input with the number of atoms of each isotope calculated by Fispact-II using natural abundance data that are stored internally. If an element whose natural abundances are not known is selected, then FISPACT-II will issue a fatal error message. Computations for these cases must use the SSFFUEL keyword.

Note that SSFFUEL and SSFMASS must not both be used in a particular case.

An example of the use of this keyword is

Example usage:

< -- Control phase -- >
...
GETXS 1 709
PROBTAB 1 0
SSFCHOOSE 4 0
 W182 W183 W184 W186
SSFMASS 1.0 1
 W 100.0
FISPACT
* COLLAPSE tal-n/gxs-709 with tp-709-294
< -- Initial phase -- > 
...
< -- Inventory phase -- > 
...

In this case pure tungsten is specified. 1 kg of tungsten containing the five stable isotopes in their natural abundances is to be used in the self-shielding calculation.

Note that SSFFUEL and SSFMASS must not both be used in the same case in the input file.

It is not essential that the total of all elements is exactly 100%. However, it is recommended that the user ensures that the total percentage of all elements equals 100%.

The SSFMASS keyword in this section applies to the collapse calculation initiated by the FISPACT keyword. The keyword may also appear in the inventory calculation section in conjunction with further GETXS keywords.