154
C. H. Pyeon
5.5 Conclusion
The ADS experiments with 100 MeV protons were carried out at KUCA to evaluate
the accuracy of experiments and calculations in subcritical states, when the kind of
solid target (W, W-Be and Pb–Bi) used was varied at the location of the target. The
analyses of neutron multiplication and subcritical multiplication factor demonstrated
a fairly good comparison between the experiments and the calculations.
Reaction rate experiments were carried out on ADS with spallation neutrons to
examine the accuracy of reaction rates by the foil activation method at various subcriticalities. A comparison between measured and calculated
115 In(n, γ)
116m In reaction
rate distributions in the subcritical cores proved the reliability of the MCNP simulations through analyses of k s . The reaction rates by the activation foils for threshold
energy were compared significantly with the discrepancy between experiments and
calculations, and the dependence of reaction rates on subcriticality. Furthermore, the
In ratio was proposed to examine neutron spectrum information on ADS by two
different In reaction rate distributions, as another neutron spectrum index, and the
validation of the In ratio was well supported by the comparison between experiments
and calculations.
Neutron spectrum experiments on spallation neutrons were conducted in the ADS
facility at KUCA to investigate the neutronic characteristics of spallation neutrons
generated at the target. The reaction rates and the continuous energy distribution of
spallation neutrons were measured by the foil activation method and by the organic
liquid scintillator, respectively. For the reaction rate experiments of
209 Bi foil, the
C/E values between the experiments and the calculations (MCNPX and ENDF/BVI) were found well within the relative difference of 10% (
209 Bi(n, xn)
210−x Bi;
x = 4–7), except for some reactions (x = 8). For continuous energy distribution experiments, the spallation neutrons were observed up to 45 MeV with the
use of the organic liquid scintillator and the numerical simulations (MCNPX with
JENDL/HE-2007 and ENDF/B-VI.6). Moreover, a suitable combination of Monte
Carlo codes and the nuclear data libraries was investigated for reaction rate analyses of high-energy neutrons and protons. The ratio of high-energy neutrons under
20 and 100 MeV protons was successfully reconstructed by combining JENDL-4.0
and the INCL model of the PHITS3.0 code, showing a relative difference of about
10% between experiments and calculations. For high-energy neutrons over 20 MeV,
the Monte Carlo codes together with JENDL/HE-2007 for high-energy neutrons
and LAHET150 for protons demonstrated significant agreement through
209 Bi(n,
xn)
210−x Bi reaction rate analyses.
References
1. Kobayashi K, Nishihara K (2000) Definition of subcriticality using the importance function
for the production of fission neutrons. Nucl Sci Eng 136:272
C. H. Pyeon
5.5 Conclusion
The ADS experiments with 100 MeV protons were carried out at KUCA to evaluate
the accuracy of experiments and calculations in subcritical states, when the kind of
solid target (W, W-Be and Pb–Bi) used was varied at the location of the target. The
analyses of neutron multiplication and subcritical multiplication factor demonstrated
a fairly good comparison between the experiments and the calculations.
Reaction rate experiments were carried out on ADS with spallation neutrons to
examine the accuracy of reaction rates by the foil activation method at various subcriticalities. A comparison between measured and calculated
115 In(n, γ)
116m In reaction
rate distributions in the subcritical cores proved the reliability of the MCNP simulations through analyses of k s . The reaction rates by the activation foils for threshold
energy were compared significantly with the discrepancy between experiments and
calculations, and the dependence of reaction rates on subcriticality. Furthermore, the
In ratio was proposed to examine neutron spectrum information on ADS by two
different In reaction rate distributions, as another neutron spectrum index, and the
validation of the In ratio was well supported by the comparison between experiments
and calculations.
Neutron spectrum experiments on spallation neutrons were conducted in the ADS
facility at KUCA to investigate the neutronic characteristics of spallation neutrons
generated at the target. The reaction rates and the continuous energy distribution of
spallation neutrons were measured by the foil activation method and by the organic
liquid scintillator, respectively. For the reaction rate experiments of
209 Bi foil, the
C/E values between the experiments and the calculations (MCNPX and ENDF/BVI) were found well within the relative difference of 10% (
209 Bi(n, xn)
210−x Bi;
x = 4–7), except for some reactions (x = 8). For continuous energy distribution experiments, the spallation neutrons were observed up to 45 MeV with the
use of the organic liquid scintillator and the numerical simulations (MCNPX with
JENDL/HE-2007 and ENDF/B-VI.6). Moreover, a suitable combination of Monte
Carlo codes and the nuclear data libraries was investigated for reaction rate analyses of high-energy neutrons and protons. The ratio of high-energy neutrons under
20 and 100 MeV protons was successfully reconstructed by combining JENDL-4.0
and the INCL model of the PHITS3.0 code, showing a relative difference of about
10% between experiments and calculations. For high-energy neutrons over 20 MeV,
the Monte Carlo codes together with JENDL/HE-2007 for high-energy neutrons
and LAHET150 for protons demonstrated significant agreement through
209 Bi(n,
xn)
210−x Bi reaction rate analyses.
References
1. Kobayashi K, Nishihara K (2000) Definition of subcriticality using the importance function
for the production of fission neutrons. Nucl Sci Eng 136:272