# The Impact of Tritium in the Environment
## 2 Artificial Sources
### Nuclear Power Engineering
The Integrated Tritium Generation (\(ITG\)) values, which are indicated by the points on the graph in Figure 3, reflect the total amount of tritium generated from the commissioning of the first nuclear power reactor (1954) to the year corresponding to each point. The modelling results indicate that the \(ITG\) values are described with high confidence (R\({}^{2}\) = 0.99) by the curve:  
\[Lg(ITG)=A+B\Big{(}1-e^{-kt}\Big{)} \tag{1}\]  
where \(A\) and \(B\) are the coefficients that determine the initial (\(A\)) and final (equilibrium) (\(A+B\)) conditions of the process, \(k\) is the rate constant, and \(t\) is the time. The value of the rate constant determines the steepness of the curve (and reflects the rate of development of nuclear power engineering) and the rate of the asymptotic reaching of the equilibrium state. The long-term dynamics of the \(ITG\) is in good accordance with global trends in nuclear energy, which correspond to the laws of global development, kinetics, and thermodynamics [24]. Analysis of the parameters of Equation (1) determined by the iteration method (\(A=12.16\); \(B=6.93\); \(k\) = 0.0621 \(y^{-1}\)) shows that given current technologies and global development trends, the tritium content in the biosphere generated by nuclear power plants will not exceed 1.23 \(\times\) 10\({}^{19}\) Bq, i.e., 10 times the natural level. Throughout the entire operation of the global nuclear power complex, almost 90% of the electricity has been generated by light-water PWRs and BWRs [24]. Meanwhile, the introduction of fusion technology can significantly disrupt the current natural and technogenic balance of tritium in the biosphere. It is worth remembering, however, that although uranium-235 reserves can be used in thermal reactors for decades (according to the ratio of reserves to production in 2024), the use of plutonium-239 in fast neutron reactors, and its conversion into uranium-238, could ensure supplies even in the medium-to-long term. This will obviously depend on the level of technological readiness of nuclear energy; the same dependence characterizes fusion as well. In the 1960s, nuclear testing injected an amount of tritium into the biosphere exceeding the natural level by more than 100 times. Importantly, the rate constant for establishing the current natural and anthropogenic balance of tritium in the biosphere is close in value to the radioactive decay constant (\(\lambda\)), which can be calculated as:  
\[\lambda=ln2/T_{1/2}=\frac{0.693}{12.33y}=0.0562\ y^{-1} \tag{2}\]  
where \(T_{1/2}\) is the half-life. Considering that the decay rate was accepted in the calculations, it can be estimated that this rate is twice as high as the rate of tritium decay. \begin{table}
\begin{tabular}{l c c c c c} \hline \hline
**Tritium Source** & **PWR** & **BWR** & **HWR** & **GCR** & **ITER \({}^{*}\)** \\ \hline Fission & \(7.5\times 10^{11}\) & \(7.5\times 10^{11}\) & \(5.5\times 10^{11}\) & \(7.5\times 10^{11}\) & \\ \hline Activation of: & & & & & \\ \hline - Deuterium & \(4.0\times 10^{7}\) & \(4.0\times 10^{7}\) & \(2.0\times 10^{13}\) & & \\ \hline - Lithium & \(7.0\times 10^{8}\) & & & \(2.0\times 10^{10}\) & \\ \hline - Boron & \(2.6\times 10^{10}\) & \(3.0\times 10^{11}\) & & & \\ \hline Totally & \(8.0\times 10^{11}\) & \(1.1\times 10^{12}\) & \(2.0\times 10^{13}\) & \(8.0\times 10^{11}\) & \(2.0\times 10^{16}\) \\ \hline Emission & \(2.3\times 10^{10}\) & \(3.8\times 10^{9}\) & \(1.8\times 10^{12}\) & \(7.3\times 10^{9}\) & \(4.0\times 10^{12}\) \\ \hline \end{tabular} Note: * expected generation and lost by fusion.  
\end{table} 
Table 1: Assessment of tritium generation and environmental emission in nuclear reactors, Bq.MWe-y\({}^{-1}\)[21; 22; 23]. Since nuclear power is the main modern source of tritium in the biosphere and it has provided an order of magnitude exceeding the global natural level, the distribution and release of tritium at the different stages of the nuclear power cycle are of special interest.