| G | SK | PHYSICS |
| G21 | USK | NUCLEONICS |
| G21 | KL | NUCLEAR PHYSICS; NUCLEAR ENGINEERING |
| G21G | UKL | CONVERSION OF CHEMICAL ELEMENTS; RADIOACTIVE SOURCES (applications of radiation in general G21H 5/00; handling particles, e.g. neutrons, or electromagnetic radiation not otherwise provided for G21K) [2] |
| G21G 1/00 | HGR | Arrangements for converting chemical elements by electromagnetic radiation, corpuscular radiation, or particle bombardment, e.g. producing radioactive isotopes (separation of different isotopes of the same element B01D 59/00) [2] |
| G21G 1/02 | UGR1 | | . | in nuclear reactors (by thermonuclear reactions G21B; conversion of nuclear fuel G21C) |
|
| G21G 1/04 | UGR1 | | . | outside of nuclear reactors or particle accelerators [2] |
|
| G21G 1/06 | UGR2 | | . . | by neutron irradiation [2] |
|
| G21G 1/08 | UGR3 | | . . . | accompanied by nuclear fission [2] |
|
| G21G 1/10 | UGR2 | | . . | by bombardment with electrically-charged particles (irradiation devices G21K 5/00) [2] |
|
| G21G 1/12 | UGR2 | | . . | by electromagnetic irradiation, e.g. with gamma or X-rays (applications of radiation G21H 5/00; irradiation devices G21K 5/00) [2] |
|
| G21G 4/00 | HGR | Radioactive sources (producing neutrons or other subatomic particles, X- or gamma rays, in fusion reactors G21B , in nuclear reactors G21C , by cosmic radiation G21H 7/00 , in accelerators H05H; X-ray tubes H01J 35/00; gamma masers H01S 4/00) [2] |
| G21G 4/02 | UGR1 | |
| G21G 4/04 | UGR1 | | . | Radioactive sources other than neutron sources (radioactive dressings A61M 36/14) [2] |
|
| G21G 4/06 | UGR2 | | . . | characterised by constructional features [2] |
|
| G21G 4/08 | UGR3 | | . . . | specially adapted for medical applications (radiation therapy using radioactive sources A61N 5/10) [2] |
|
| G21G 4/10 | UGR2 | | . . | with radium emanation [2] |
|
| G21G 5/00 | HGR | Alleged conversion of chemical elements by chemical reaction |