# A Feasibility Study of Utilizing Nuclear Energy for an Existing MED-TVC Desalination Plant
## 4 Water Cost Estimation
### Nuclear Heating Reactor  
A modified version of the Chinese nuclear heating reactor NHR200-II [16; 17] shown in Figure 4 is selected with a power output of 169 MW (th) and coupled with a MED-TVC desalination plant, where the new reactor version is named as NHR170. Table 7 shows the main operating parameters for the two reactors. The NHR-170 has almost the same characteristics as the NHR200-II except that the thermal power output is smaller, and the operating cycle length is higher. Hence, the reactor core design for NHR170 is changed in terms of fuel enrichment, fuel assembly loading pattern, and primary side mass flow rate. \begin{table}
\begin{tabular}{l c} \hline \hline Temperature of MP Steam from Heat Source (\({}^{\circ}\)C) & 230 \\ \hline Temperature of the motive steam (\({}^{\circ}\)C) & 201.3 \\ \hline Maximum brine temperature (\({}^{\circ}\)C) & 70 \\ \hline SG approach temperature (\({}^{\circ}\)C) & 28.6 \\ \hline SG pump head (bar) & 3.5 \\ \hline MED number of effects & 10 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: MED-TVC input parameters in DEEP. The thermal power output of NHR170, which is 169 MW (th), is selected in DEEP to estimate the cost of the desalinated water. Figure 5 shows a schematic diagram of the NHR170 coupled with the MED-TVC. The reactor is dedicated to producing steam only for the purpose of freshwater production. The primary side of the reactor, namely the RCS (Reactor Coolant System), is considered to be within the RPV (Reactor Pressure Vessel), where an IHX (Intermediate Heat Exchanger) is placed inside the RPV. An IL (Intermediate Loop) is transferring heat from the RCS to the SG to produce the required motive steam to drive the MED-TVC unit. The purpose of the IL is to prevent any leakage of radioactive materials to the desalination plant, and it is better for it to be at a pressure higher than the RCS pressure, so in the case of any tube rupture in IHX, the fluid in the intermediate loop enters on the RCS side. Thus, radioactive materials will be contained within the RCS loop. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **Unit** & **NHR200-II** & **NHR170** \\ \hline Thermal Power & MW (th) & 200 & 169 \\ \hline Reactor Coolant & - & Light water & Light Water \\ \hline Primary Side Circulation Type & - & Natural circulation & Natural circulation \\ \hline Primary Side Pressure & bar & 80 & 80 \\ \hline Core Inlet/Outlet Temperature & \({}^{\circ}\)C & 232/280 & 232/280 \\ \hline Intermediate Loop (IL) Pressure & bar & 88 & 88 \\ \hline IL Cold/Hot Leg Temperature & \({}^{\circ}\)C & 203/248 & 203/248 \\ \hline Motive Steam Pressure & bar & 16 & 15.4 \\ \hline Motive Steam Temperature & \({}^{\circ}\)C & 201.4 & 201.3 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Main Operating Parameters for NHR200-II and NHR170. Figure 4: Structure and cross section of the NHR200-II. The economic parameters for the NHR170 that are used in the DEEP analysis are addressed in Table 8.  
Excluding site-related costs and project contingencies, specific construction costs simply refer to the overnight construction cost, which is the cost of constructing the plant assuming there is no interest incurred during the construction period, as if the project had been completed over one night [18]. It is worth mentioning that the DEEP default value for the specific construction cost for nuclear heating reactors is USD 1300/kW (th). Although the NHR200-I's specific construction cost is USD 535/kW (th) [19], this cost was estimated at site-specific conditions in China nearly two decades ago, and all associated costs related to capital investment have since increased. Hence, in this analysis, the value of the specific construction cost was reasonably selected to be USD 1100/kW (th). Assumed values for the discount rate and IDC (Interest during Construction) rate are considered acceptable since the water market in Saudi Arabia is centralized. Usually, the Saudi government supports such projects, which contributes to reducing the overall risk of the project.