Doel 3 & Tihange 2 - Some Peer-reviewed Scientific Papers & Reports

6.3. In-service hydrogen generation

of the software is difficult to prove. It is however possible to compare the results for a simulation in PWR primary water chemistry conditions in the absence of radiation, to the H 2 concentration of dissolved H 2 in the primary water. A simulation for the conditions at the begin of cycle for a typical PWR is performed. The exact values for each of the parameters can be found in Table 6.3. Figure 6.8 gives the resulting concentrations for each of the chemical species. Table 6.3: Values for the parameters used for the conditions at the beginning of cycle in the absence of radiation.

Value

Unit

Temperature

300 150

◦ C

Pressure

bar

Boron

2400

ppm ppm

Lithium

5

3 /kg

H 2 O 2

35 STP cm

0.001 0.001

ppm ppm R/s R/s R/s

H 2 O 2

γ -radiation

0

neutron-radiation 0

α -radiation

0

The steady state concentration of H in the primary water is found to be 2.9 10 -20 mol/l, for typical conditions at the beginning of cycle in the absence of radiation. Again, for this concentration, one can calculate the equilibrium H 2 fugacity in the primary system. Following the same calculation as before, one can find: f H = c H H H = 2 . 9 · 10 − 17 20 . 0 · 10 − 6 = 1 . 45 · 10 − 12 Pa (6.12) and f H 2 = f 2 H K Dis = (1 . 45 · 10 − 12 ) 2 3 . 76 · 10 − 30 = 5 . 6 · 10 5 Pa (6.13) The equilibrium H 2 fugacity for the concentration of atomic H in the primary water is found to be 5.6 10 5 Pa. This corresponds to 5.5 atm. This can be compared to the actual equilibrium pressure for the dissolved H 2 in the primary water, as both should be in equilibrium. The equilibrium H 2 pressure 69