Review Article

Overview and Discussion of the OECD/NRC Benchmark Based on NUPEC PWR Subchannel and Bundle Tests

Table 10

Sources of error for void distribution measurement.

Error sourceChordal averaged CT averaged
Steady stateTransient

γ-ray measurement
 Effect of surrounding condition (magnetic field and temperature)
 on measurement system
 Randomness of γ-ray source decay0.02%0.2%0.1%
 Correction error due to background 0.0%0.0%0.0%
 Correction error due to counting loss<0.5%<0.5%<0.1%
 Calibration error 0.1%0.1%0.1%
 Correction error due to attenuation by surrounding water0.0%0.0%
 Correction error due to scattering from multi-γ-rays<0.2%<0.2%


Subchannel density
 Transfer to density<9 kg/m3<10 kg/m3<15 kg/m3
 Distribution error to subchannel<5 kg/m3<5 kg/m3
Correlation error from chordal averaged to CT averaged<6 kg/m3<6 kg/m3

Subchannel density<20 kg/m3<21 kg/m3<15 kg/m3
Subchannel void*0.0400.0420.030
Uncertainty (1σ)4%5%3%

 *Reference averaged density is 500 kg/m3.