| 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 26 | | .~.~.~ Moderator being substantially not pressurized (e.g., swimming-pool reactor [G21C-1/14] *** (DIG. 30 takes precedence) {1} |
| DIG 27 | DD | .~.~.~.~> Moderator and coolant being different or separated (e.g., sodium-graphite reactor, sodium-heavy water reactor, organic coolant-heavy water reactor) [G21C-1/16] {1} |