What is the critical mass of uranium 238?
Critical mass of a bare sphere
| Nuclide | Half-life (y) | Critical mass (kg) |
|---|---|---|
| uranium-235 | 703,800,000 | 52 |
| neptunium-236 | 154,000 | 7 |
| neptunium-237 | 2,144,000 | 60 |
| plutonium-238 | 87.7 | 9.04–10.07 |
What is the critical mass of plutonium?
approximately 10 kg
The critical mass of a bare sphere of uranium-235 at normal density is approximately 47 kg (104 pounds); for plutonium-239, critical mass is approximately 10 kg (22 pounds).
What is the mass of plutonium 238?
238.049553 u
Plutonium-238
| General | |
|---|---|
| Isotope mass | 238.049553 u |
| Spin | 0 |
| Decay modes | |
| Decay mode | Decay energy (MeV) |
What is critical mass in a nuclear reactor?
Critical mass, in nuclear physics, the minimum amount of a given fissile material necessary to achieve a self-sustaining fission chain reaction under stated conditions.
What happens if critical mass is reached?
When the actual critical mass is reached nothing happens, so that to produce a nuclear explosion you need several critical masses—about three. In that case more neutrons will be produced in the interior than will leak through the surface; as a result a self-sustaining chain reaction will occur.
What percentage is critical mass?
For a critical mass to be reached, you typically need between 5% and 25% of the population. The point where critical mass is achieved is often called the ‘tipping point’.
What element has a mass of 238?
uranium
The atomic number of uranium (see periodic table) is 92, and the mass number of the isotope is given as 238.
What happens if critical mass is not reached?
What is the critical mass of Pu-238?
The prompt critical mass of a metal sphere of Pu-238 at normal density is about 9.5 kg. With a steel neutron reflector this could be made as small as about 4.7 kg. Pu-238 is not a good choice for a bomb due to its very high decay heat and very strong radioactivity.
Can a Pu-238 bomb be made prompt critical?
Pu-238 can be made prompt critical and it can detonate. The prompt critical mass of a metal sphere of Pu-238 at normal density is about 9.5 kg. With a steel neutron reflector this could be made as small as about 4.7 kg. Pu-238 is not a good choice for a bomb due to its very high decay heat and very strong radioactivity.
Can a sphere of Pu-238 be made critical?
Pu-238 can be made prompt critical and it can detonate. The prompt critical mass of a metal sphere of Pu-238 at normal density is about 9.5 kg.
Which is more dangerous Pu-238 or Pu-240?
There is a significant spontaneous fission rate for Pu-238 too, which will be more of a problem than for Pu-239, which is typically polluted by some fraction of Pu-240, whose spontaneous fission rate is already high enough to provide a significant neutron background. Pu-240 has a spontaneous fission half-life which is about 1/10 that of Pu-238.