Definitions, units and constants
Definitions
- ZA defines the element and isotope as 1000
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 Z + 10 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 | |
| Area | cm2 | |
| Volume | cm3 | |
| Time | s | depends on the case |
| Energy | MeV | |
| Microscopic cross section | b | barn = 10-24 cm2 |
| Macroscopic cross section | 1/cm | |
| Mass | g | |
| Mass density | g/cm3 | |
| Atomic density | 1024/cm3 | ( = b-1cm-1) |
| Power | W | |
| Power density | kW/g | |
| 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 |
