Technetium-99
General | |
---|---|
Decay mode | Decay energy (MeV) |
Beta decay | 0.2975 |
Isotopes of technetium Complete table of nuclides |
Technetium-99 (99Tc) is an isotope of
The metastable
Radiation
The weak beta emission is stopped by the walls of laboratory glassware. Soft X-rays are emitted when the beta particles are stopped, but as long as the body is kept more than 30 cm away these should pose no problem. The primary hazard when working with technetium is inhalation of dust; such radioactive contamination in the lungs can pose a significant cancer risk.[citation needed]
Role in nuclear waste
Thermal
|
Fast
|
14 MeV
| |
---|---|---|---|
232Th | not fissile | 2.919 ± .076 | 1.953 ± 0.098 |
233U | 5.03 ± 0.14 | 4.85 ± 0.17 | 3.87 ± 0.22 |
235U | 6.132 ± 0.092 | 5.80 ± 0.13 | 5.02 ± 0.13 |
238U | not fissile | 6.181 ± 0.099 | 5.737 ± 0.040 |
239Pu | 6.185 ± 0.056 | 5.82 ± 0.13 | ? |
241Pu | 5.61 ± 0.25 | 4.1 ± 2.3 | ? |
Due to its high fission yield, relatively long half-life, and mobility in the environment, technetium-99 is one of the more significant components of nuclear waste. Measured in becquerels per amount of spent fuel, it is the dominant producer of radiation in the period from about 104 to 106 years after the creation of the nuclear waste.
Releases
Nuclide | t1⁄2
|
Yield | Q[a 1] | βγ
|
---|---|---|---|---|
( Ma )
|
(%)[a 2] | ( keV )
|
||
99Tc | 0.211 | 6.1385 | 294 | β |
126Sn
|
0.230 | 0.1084 | 4050[a 3] | βγ |
79Se | 0.327 | 0.0447 | 151 | β |
135Cs
|
1.33 | 6.9110[a 4] | 269 | β |
93Zr
|
1.53 | 5.4575 | 91 | βγ |
107Pd
|
6.5 | 1.2499 | 33 | β |
129I | 15.7 | 0.8410 | 194 | βγ |
An estimated 160
In the environment
The long half-life of technetium-99 and its ability to form an
Separation of technetium-99
Several methods have been proposed for technetium-99 separation including: crystallization,[4][5] liquid-liquid extraction,[6][7][8] molecular recognition methods,[9] volatilization, and others.
In 2012 the crystalline compound Notre Dame Thorium Borate-1 (NDTB-1) was presented by researchers at the University of Notre Dame. It can be tailored to safely absorb radioactive ions from nuclear waste streams. Once captured, the radioactive ions can then be exchanged for higher-charged species of a similar size, recycling the material for re-use. Lab results using the NDTB-1 crystals removed approximately 96 percent of technetium-99.[10][11]
Transmutation of technetium to stable ruthenium-100
An alternative disposal method, transmutation, has been demonstrated at CERN for technetium-99. This transmutation process bombards the technetium (99
Tc as a metal target) with neutrons, forming the short-lived 100
Tc (half-life 16 seconds) which decays by beta decay to stable ruthenium (100
Ru). Given the relatively high market value of Ruthenium[12] and the particularly undesirable properties of Technetium, this type of nuclear transmutation appears particularly promising.
See also
- Isotopes of technetium
- List of elements facing shortage
- Technetium-99m
References
- IAEA. Retrieved 18 December 2020.
- ^ a b K. Yoshihara, "Technetium in the Environment" in "Topics in Current Chemistry: Technetium and Rhenium", vol. 176, K. Yoshihara and T. Omori (eds.), Springer-Verlag, Berlin Heidelberg, 1996.
- ISSN 1345-4749.
- ISSN 0020-1669.
- PMC 9916763.
- ISSN 1588-2780.
- ISSN 0236-5731.
- .
- ISSN 1588-2780.
- ^ William G. Gilroy (Mar 20, 2012). "New Method for Cleaning Up Nuclear Waste". Science Daily.
- S2CID 96158262.
- ^ "Daily Metal Price: Ruthenium Price Chart (USD / Kilogram) for the Last 2 years".