scholarly journals Generation of the 1H in H2O neutron thermal scattering law covariance matrix of the CAB model

2018 ◽  
Vol 4 ◽  
pp. 32
Author(s):  
Juan Pablo Scotta ◽  
Gilles Noguère ◽  
Jose Ignacio Marquez Damian
Keyword(s):  
Covariance Matrix ◽  
Nuclear Data ◽  
Water Model ◽  
Dynamic Simulations ◽  
Light Water ◽  
Thermal Scattering ◽  
Data Libraries ◽  
Hydrogen Bound ◽  
Nuclear Data Libraries ◽  
Evaluated Nuclear Data

The thermal scattering law (TSL) of 1H in H2O describes the interaction of the neutron with the hydrogen bound to light water. No recommended procedure exists for computing covariances of TSLs available in the international evaluated nuclear data libraries. This work presents an analytic methodology to produce such a covariance matrix-associated to the water model developed at the Atomic Center of Bariloche (Centro Atomico Bariloche, CAB, Argentina). This model is called as CAB model, it calculates the TSL of hydrogen bound to light water from molecular dynamic simulations. The performance of the obtained covariance matrix has been quantified on integral calculations at “cold” reactor conditions between 20 and 80∘ C. For UOX fuel, the uncertainty on the calculated reactivity ranges from ±71 to ±155 pcm. For MOX fuel, it ranges from ±110 to ±203 pcm.

scholarly journals Evaluating nuclear data and their uncertainties

2018 ◽  
Vol 4 ◽  
pp. 29
Author(s):  
Patrick Talou
Keyword(s):  
Experimental Data ◽  
Uncertainty Quantification ◽  
Cross Sections ◽  
Coming Out ◽  
Nuclear Data ◽  
Covariance Matrices ◽  
Alternative Approaches ◽  
Data Libraries ◽  
Nuclear Data Libraries ◽  
Evaluated Nuclear Data

In the last decade or so, estimating uncertainties associated with nuclear data has become an almost mandatory step in any new nuclear data evaluation. The mathematics needed to infer such estimates look deceptively simple, masking the hidden complexities due to imprecise and contradictory experimental data and natural limitations of simplified physics models. Through examples of evaluated covariance matrices for the soon-to-be-released U.S. ENDF/B-VIII.0 library, e.g., cross sections, spectrum, multiplicity, this paper discusses some uncertainty quantification methodologies in use today, their strengths, their pitfalls, and alternative approaches that have proved to be highly successful in other fields. The important issue of how to interpret and use the covariance matrices coming out of the evaluated nuclear data libraries is discussed.

Benchmark Calculations for Reflector Effect in Fast Cores by Using the Latest Evaluated Nuclear Data Libraries

2014 ◽  
Vol 118 ◽  
pp. 405-409
Author(s):  
M. Fukushima ◽  
M. Ishikawa ◽  
K. Numata ◽  
T. Jin ◽  
T. Kugo
Keyword(s):  
Nuclear Data ◽  
Data Libraries ◽  
Nuclear Data Libraries ◽  
Evaluated Nuclear Data

scholarly journals Measurement of leakage neutron spectra with D-T neutrons and evaluated nuclear data

2020 ◽  
Vol 239 ◽  
pp. 18009
Author(s):  
Rui Han ◽  
Zhiqiang Chen ◽  
Guoyu Tian ◽  
Yangbo Nie ◽  
Fudong Shi ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Nuclear Data ◽  
Neutron Spectra ◽  
Neutron Reaction ◽  
Partial Energy ◽  
Reaction Channels ◽  
Neutron Leakage ◽  
Data Libraries ◽  
Nuclear Data Libraries ◽  
Evaluated Nuclear Data

Benchmarking of evaluated neutron nuclear data libraries was performed for ∼14.8 MeV neutrons on the several targets, such as gallium, graphite, silicon carbide, uranium and tungsten samples. The experiments were performed at China Institute of Atomic Energy (CIAE). The neutron leakage spectra from the samples were measured at 60◦ and 120◦ by a TOF technique with a BC501A scintillation detector. The measured spectra are rather well reproduced by MCNP-4C simulations with the CENDL3.1, JENDL-4.0 and the new release ENDF/B-VIII.0, JEFF-3.3 evaluated nuclear data libraries and so on. There have some difference between experiments and simulations for the elastic and inelastic contributions in the partial energy range. And the discrepancies of the neutron leakage spectra in the MCNP simulations originate simply from the differences in the spectra distributions of the neutron reaction channels in the evaluated nuclear data libraries.

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