Waste uranium from the nuclear reactors is called as
Depleted uranium
Understanding Waste Uranium from Nuclear Reactors
Nuclear reactors use specific types of uranium as fuel to generate energy. During the process, or in associated steps of the nuclear fuel cycle, different forms of uranium are produced, including waste materials.
Let's examine the options provided to understand what waste uranium from nuclear reactors is typically called.
Analyzing the Options
- Enriched uranium: This refers to uranium where the concentration of the fissile isotope, Uranium-235 ($\text{U-235}$), has been increased above its natural level (about 0.7%). Enriched uranium is the fuel used in most light water reactors. It is a valuable fuel material, not a waste product in this context.
- Depleted uranium: This is uranium that has a lower concentration of $\text{U-235}$ than natural uranium (typically 0.2% to 0.3% $\text{U-235}$). It is primarily composed of Uranium-238 ($\text{U-238}$). Depleted uranium is a byproduct of the uranium enrichment process, where natural uranium is processed to increase the $\text{U-235}$ content for fuel. It can also be the residual uranium recovered from reprocessing spent nuclear fuel. Because it has a reduced amount of the fissile isotope, it is considered a waste material or a low-value byproduct for energy production purposes, although it has other applications due to its high density.
- Fertile uranium: This term refers to isotopes that are not fissile themselves but can be converted into fissile material through neutron capture. The most common example is $\text{U-238}$, which is the main component of both natural and depleted uranium. $\text{U-238}$ can capture a neutron and, after a series of decays, become Plutonium-239 ($\text{Pu-239}$), which is fissile. So, fertile uranium is a type of material based on its nuclear properties, not necessarily a waste product name.
- Fissile uranium: This refers to isotopes that can undergo fission and sustain a nuclear chain reaction, such as $\text{U-235}$ and $\text{Pu-239}$. Fissile material is the core component of nuclear fuel. It is a valuable material for energy production, not a waste product in itself, though it is consumed during the fission process.
Conclusion on Waste Uranium
Considering the definitions, "waste uranium from nuclear reactors" most accurately describes depleted uranium. While spent fuel from a reactor is indeed waste, it contains fission products, transuranics, and uranium (both $\text{U-238}$ and some remaining $\text{U-235}$). If the uranium component is separated from spent fuel through reprocessing, this reprocessed uranium typically has a reduced $\text{U-235}$ content compared to fresh fuel and shares characteristics with depleted uranium. More broadly, depleted uranium produced during the initial enrichment process (which is essential for creating reactor fuel) is a significant form of uranium waste associated with the nuclear fuel cycle that supports reactors.
Therefore, depleted uranium fits the description of waste uranium due to its low fissile content, making it unsuitable for direct use as fuel in most reactors.
| Uranium Type | Description | Relevance to Waste |
|---|---|---|
| Enriched uranium | Higher than natural $\text{U-235}$ content | Used as fuel, not waste |
| Depleted uranium | Lower than natural $\text{U-235}$ content | Byproduct of enrichment or reprocessing; considered waste uranium |
| Fertile uranium ($\text{U-238}$) | Can become fissile (e.g., $\text{Pu-239}$) | Property of an isotope, not a waste name |
| Fissile uranium ($\text{U-235}$) | Can sustain chain reaction | Key component of fuel, not waste itself |
Based on this analysis, the waste uranium from the nuclear reactors (or the associated fuel cycle) is called depleted uranium.
Revision Table: Nuclear Uranium Forms
| Term | Meaning | Key Isotope Example |
|---|---|---|
| Natural Uranium | Uranium as found in nature | ~0.7% $\text{U-235}$, ~99.3% $\text{U-238}$ |
| Enriched Uranium | $\text{U-235}$ concentration increased | Typically 3-5% $\text{U-235}$ for reactor fuel |
| Depleted Uranium | $\text{U-235}$ concentration decreased | Typically 0.2-0.3% $\text{U-235}$, mostly $\text{U-238}$ |
| Fertile Material | Can be converted to fissile material | $\text{U-238}$, Thorium-232 ($\text{Th-232}$) |
| Fissile Material | Can sustain a nuclear chain reaction | $\text{U-235}$, $\text{Pu-239}$ |
Additional Information on Depleted Uranium
Depleted uranium is primarily composed of Uranium-238. While it is considered waste from the perspective of nuclear fuel enrichment, it is not without uses. Due to its high density (about 1.7 times denser than lead), it is used in applications like:
- Counterweights in aircraft
- Radiation shielding
- Kinetic energy penetrators (in military applications)
Although its radioactivity is lower than natural or enriched uranium because of the reduced $\text{U-235}$ content, it is still a heavy metal and poses chemical toxicity risks if ingested or inhaled. Its long half-life means it remains radioactive for a very long time, requiring careful storage and handling.
Important Questions from Miscellaneous
A stone is thrown horizontally from the top of a 20 m high building with a speed of 12 m/s. It hits the ground at a distance R from the building. Taking g = 10 m/s2 and neglecting air resistance will give :
A sphere of volume V is made of a material with lower density than water. While on Earth, it floats on water with its volume f1V (f1 < 1) submerged. On the other hand, on a spaceship accelerating with acceleration a < g (g is the acceleration due to gravity on Earth) in outer space, its submerged volume in water is f2V. Then:
A railway wagon (open at the top) of mass M1 is moving with speed v1 along a straight track. As a result of rain, after some time it gets partially filled with water so that the mass of the wagon becomes M2 and speed becomes v2. Taking the rain to be falling vertically and the water stationery inside the wagon, the relation between the two speeds v1 and v2 is :
Consider the following statements:
1. Distance between the longitudes becomes zero on North Pole and South Pole.
2. Distance between the longitudes is maximum on the Equator.
3. Number of longitudes is more than number of latitudes.
Which of the statements given above is/are correct?
One block of 2⋅0 kg mass is placed on top of another block of 3⋅0 kg mass. The coefficient of static friction between the two blocks is 0⋅2. The bottom block is pulled with a horizontal force F such that both the blocks move together without slipping. Taking acceleration due to gravity as 10 m/s2, the maximum value of the frictional force is :
