| 976 / | HD | NUCLEAR TECHNOLOGY |
| DIG 5 | DD | NUCLEAR REACTORS [G21C-1/00] *** (fusion reactors H05H-1/00; nuclear explosives DIG. 423; analogue computers therefor G06G-7/54) {4} |
| DIG 16 | DD | .~ Thermal reactors; Epithermal reactors [G21C-1/04] {2} |
| DIG 17 | DD | .~.~ Heterogeneous reactors (i.e., in which the fuel and moderator are separated) [G21C-1/06] {4} |
| DIG 19 | DD | .~.~.~ Moderator being highly pressurized (e.g., boiling water reactor; integral super-heat reactor; pressurized water reactor) [G21C-1/08] *** (DIG. 30 takes precedence) {5} |
| DIG 24 | | .~.~.~.~ Moderator and coolant being different or separated [G21C-1/10] {1} |
| DIG 25 | DD | .~.~.~.~.~> Moderator being solid (e.g., Magnox reactor, gas-graphite reactor [G21C-1/12] |