Definitions, units and constants

Definitions

• ZA defines the element and isotope as 1000 $\times$ Z + A, where Z is the proton number and A is the mass number. For example, the ZA for U-235 is 92235.
• ZA.id defines nuclides in cross section data libraries. ZA identifies the nuclide and id is the library id (for example, 92235.09c).
• ZAI defines the element, isotope and isomeric state as 10000 $\times$ Z + 10 $\times$ A + I, where Z is the proton number, A is the mass number and I is the isomeric state. For example, the ZAI for U-235 is 922350 and the ZAI for Am-242m is 952421.

Units

Quantity	Unit	Notes
Distance	cm	Apart from solid 2 (unstructured mesh) points file which are in m
Area	cm2
Volume	cm3
Time	s	depends on the context
Energy	MeV
Microscopic cross section	b	barn = 10-24 cm2
Macroscopic cross section	1/cm
Mass	g or kg	depends on the parameter
Mass density	g/cm3
Atomic density	1024/cm3	( = b-1cm-1)
Power	W
Power density	kW/g	(= MW/Kg)
Temperature	K
Particle flux	1/cm2s
Reaction rate	1/cm3s	reaction rate density
Burnup	MWd/kgU	per total initial heavy metal
Burn time	days

Constants

Constant	Value	Units	Notes
INFTY	1037	N/A	Used to denote infinity
ZERO	10-37	N/A	The smallest nonzero absolute value