넵투늄 동위 원소
표

| 핵종 기호 | Z(p)> 들뜬 에너지 | N(n)> 들뜬 에너지 |   동위 원소 질량 (u)  > 들뜬 에너지 | 반감기 | 붕괴 방식 | 붕괴 생성물 | 핵 스핀 |
| --- | --- | --- | --- | --- | --- | --- | --- |
| 225Np | 93 | 132 | 225.03391(8) | 3# ms [>2 µs] | α | 221Pa | 9/2-# |
| 226Np | 93 | 133 | 226.03515(10)# | 35(10) ms | α | 222Pa |  |
| 227Np | 93 | 134 | 227.03496(8) | 510(60) ms | α (99.95%) | 223Pa | 5/2-# |
| 227Np | 93 | 134 | 227.03496(8) | 510(60) ms | β+ (0.05%) | 227U | 5/2-# |
| 228Np | 93 | 135 | 228.03618(21)# | 61.4(14) s | β+ (59%) | 228U |  |
| 228Np | 93 | 135 | 228.03618(21)# | 61.4(14) s | α (41%) | 224Pa |  |
| 228Np | 93 | 135 | 228.03618(21)# | 61.4(14) s | β+, SF (0.012%) | 다양 |  |
| 229Np | 93 | 136 | 229.03626(9) | 4.0(2) min | α (51%) | 225Pa | 5/2+# |
| 229Np | 93 | 136 | 229.03626(9) | 4.0(2) min | β+ (49%) | 229U | 5/2+# |
| 230Np | 93 | 137 | 230.03783(6) | 4.6(3) min | β+ (97%) | 230U |  |
| 230Np | 93 | 137 | 230.03783(6) | 4.6(3) min | α (3%) | 226Pa |  |
| 231Np | 93 | 138 | 231.03825(5) | 48.8(2) min | β+ (98%) | 231U | (5/2)(+#) |
| 231Np | 93 | 138 | 231.03825(5) | 48.8(2) min | α (2%) | 227Pa | (5/2)(+#) |
| 232Np | 93 | 139 | 232.04011(11)# | 14.7(3) min | β+ (99.99%) | 232U | (4+) |
| 232Np | 93 | 139 | 232.04011(11)# | 14.7(3) min | α (0.003%) | 228Pa | (4+) |
| 233Np | 93 | 140 | 233.04074(5) | 36.2(1) min | β+ (99.99%) | 233U | (5/2+) |
| 233Np | 93 | 140 | 233.04074(5) | 36.2(1) min | α (0.001%) | 229Pa | (5/2+) |
| 234Np | 93 | 141 | 234.042895(9) | 4.4(1) d | β+ | 234U | (0+) |
| 235Np | 93 | 142 | 235.0440633(21) | 396.1(12) d | ε | 235U | 5/2+ |
| 235Np | 93 | 142 | 235.0440633(21) | 396.1(12) d | α (0.0026%) | 231Pa | 5/2+ |
| 236Np | 93 | 143 | 236.04657(5) | 1.54(6)×105 a | ε (87.3%) | 236U | (6-) |
| 236Np | 93 | 143 | 236.04657(5) | 1.54(6)×105 a | β- (12.5%) | 236Pu | (6-) |
| 236Np | 93 | 143 | 236.04657(5) | 1.54(6)×105 a | α (0.16%) | 232Pa | (6-) |
| 236mNp | 60(50) keV | 60(50) keV | 60(50) keV | 22.5(4) h | ε (52%) | 236U | 1 |
| 236mNp | 60(50) keV | 60(50) keV | 60(50) keV | 22.5(4) h | β- (48%) | 236Pu | 1 |
| 237Np | 93 | 144 | 237.0481734(20) | 2.144(7)×106 a | α | 233Pa | 5/2+ |
| 237Np | 93 | 144 | 237.0481734(20) | 2.144(7)×106 a | SF (2×10−10%) | 다양 | 5/2+ |
| 237Np | 93 | 144 | 237.0481734(20) | 2.144(7)×106 a | CD (4×10−12%) | 207Tl 30Mg | 5/2+ |
| 238Np | 93 | 145 | 238.0509464(20) | 2.117(2) d | β- | 238Pu | 2+ |
| 238mNp | 2300(200)# keV | 2300(200)# keV | 2300(200)# keV | 112(39) ns |  |  |  |
| 239Np | 93 | 146 | 239.0529390(22) | 2.356(3) d | β- | 239Pu | 5/2+ |
| 240Np | 93 | 147 | 240.056162(16) | 61.9(2) min | β- | 240Pu | (5+) |
| 240mNp | 20(15) keV | 20(15) keV | 20(15) keV | 7.22(2) min | β- (99.89%) | 240Pu | 1(+) |
| 240mNp | 20(15) keV | 20(15) keV | 20(15) keV | 7.22(2) min | IT (0.11%) | 240Np | 1(+) |
| 241Np | 93 | 148 | 241.05825(8) | 13.9(2) min | β- | 241Pu | (5/2+) |
| 242Np | 93 | 149 | 242.06164(21) | 2.2(2) min | β- | 242Pu | (1+) |
| 242mNp | 0(50)# keV | 0(50)# keV | 0(50)# keV | 5.5(1) min |  |  | 6+# |
| 243Np | 93 | 150 | 243.06428(3)# | 1.85(15) min | β- | 243Pu | (5/2-) |
| 244Np | 93 | 151 | 244.06785(32)# | 2.29(16) min | β- | 244Pu | (7-) |
↑  약자:
CD: 뭉치 붕괴
ε: 전자 포획
IT: 이성질핵 전이
SF: 자발 핵분열
↑  핵분열성 핵종
↑  가장 일반적인 핵종