Uncertainties and Covariances of the Neutron Cross Sections for Th-232 and U-233

E.V.Gai, E.V.Gai, A.V.IgnatyukA.V.Ignatyuk

Institute of Physics and Power Engineering, ObninskInstitute of Physics and Power Engineering, Obninsk

Available experimental data on the neutron cross sections are analyzed on the basis of the unrecognized error-estimation method (UEEM) ;

Estimated uncertainties are compared with the ENDF/A-VII and JENDL-4 evaluations;

Main contradictions between the evaluated uncertainties are noted.

Consultants’ Meeting on Th/U Data, Vienna, 20-22 December 2010

Main relationsMain relations

A minimized functional for a set of experimental data Fi can be written as

where ωij = ωiδij + Sij is the weighting function that includes the statistical and systematic

uncertainties, is the approximating function that depends from the corresponding parameters α, β and so on. Uncertainties of parameters are defined by the matrix

and uncertainties of the approximating function are defined by the matrix

.

.

ijiji

ij ij

ii yxfF

S 2

2,...)],;([

)()( j

ij

iij

xfxfZ

)()()(),( 1 ji

jixfxf

Zxx

,...),;( ixf

Experimental data on the total cross section of Th-232 in Experimental data on the total cross section of Th-232 in comparison with the recent evaluationscomparison with the recent evaluations

Evaluated uncertainties for the total cross section of Th-232Evaluated uncertainties for the total cross section of Th-232

Experimental data on the fission cross section of Experimental data on the fission cross section of Th-232 in comparison with the recent evaluationsTh-232 in comparison with the recent evaluations

Uncertainties for the fission cross section of Th-232Uncertainties for the fission cross section of Th-232

Experimental data on the prompt nu-bar for Th-232 Experimental data on the prompt nu-bar for Th-232 in comparison with the recent evaluationsin comparison with the recent evaluations

Uncertainties of the prompt nu-bar for Th-232Uncertainties of the prompt nu-bar for Th-232

Experimental data on the Th-232(n,gam) cross section in Experimental data on the Th-232(n,gam) cross section in comparison with the recent evaluationscomparison with the recent evaluations

Uncertainties for the Th-232(n,gam) cross sectionUncertainties for the Th-232(n,gam) cross section

Experimental data on the inelastic cross section of Experimental data on the inelastic cross section of Th-232 in comparison with the recent evaluationsTh-232 in comparison with the recent evaluations

Uncertainties for the inelastic cross section of Th-232Uncertainties for the inelastic cross section of Th-232

Experimental data on the total cross section of U-233 in Experimental data on the total cross section of U-233 in comparison with the recent evaluationscomparison with the recent evaluations

Evaluated uncertainties for the total cross section of U-233Evaluated uncertainties for the total cross section of U-233

Experimental data on the fission cross section of Experimental data on the fission cross section of U-233 in comparison with the recent evaluationsU-233 in comparison with the recent evaluations

Uncertainties for the U-233(n,f) cross sectionUncertainties for the U-233(n,f) cross section

Prompt fission-neutron multiplicities for U-233Prompt fission-neutron multiplicities for U-233

0 5 10 15 202.0

2.5

3.0

3.5

4.0

4.5

5.0

5.5

U-233

Fis

sion

neu

tron

mul

tiplic

ity

Neutron Energy, MeV

exp JENDL-3.3 ENDF/B-VII Minsk 2003 Pade-5

Uncertainties of the prompt nu-bar for U-233Uncertainties of the prompt nu-bar for U-233

Experimental data on the U-233(n,gam) cross section in Experimental data on the U-233(n,gam) cross section in comparison with the recent evaluationscomparison with the recent evaluations

Uncertainties for the U-233(n,gam) cross sectionUncertainties for the U-233(n,gam) cross section

Uncertainties for the inelastic cross section of U-233 Uncertainties for the inelastic cross section of U-233