Some fission yields for 235U (n,f), 239Pu (n,f), 238U (n,f) reactions in ΣΣ neutron spectrum Dr....
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Transcript of Some fission yields for 235U (n,f), 239Pu (n,f), 238U (n,f) reactions in ΣΣ neutron spectrum Dr....
Some fission yields forSome fission yields for235U (n,f), 239Pu (n,f), 238U (n,f) 235U (n,f), 239Pu (n,f), 238U (n,f) reactions in ΣΣ neutron spectrumreactions in ΣΣ neutron spectrum
Dr. Cristina GarleaNational Institute for R&D of Physics and Nuclear Engineering “Horia Hulubei”, Magurele, Romania
Dr. Ion Garlea
SENDRA – Nuclear Technology Ltd., Bucharest, Romania
ΣΣ–ITN facility in thermal column of VVR-S Magurele reactor
1 - ΣΣ–ITN system; 2 - CB4 screen; 3 - Vertical plug; 4 - Horizontal plug; 5 - Cavity in graphite
Comparison between neutron spectrum calculatedby ANISN code and that determined by SAND II
Characteristics: - conversion factor: 0.731- average energy of spectrum: 0.791 MeV- flux (2 MW) E ≥ 10 keV: 3.385 x 1013 n/m2s E > 1 MeV: 8.1 x 1012 n/m2s
Comparison between measured and calculated ΣΣ spectrum
Characterization in the intermediate energy range
± 15% E < 0.1 keV multiple foil methods
± 5% 0.1 keV ≤ E ≤ 2 MeV spectrometry and calculation
± 5% E > 2 MeV multiple foil methods
Method
• Neutron flux measuring in the place of detector exposure by absolutely calibrated fission chambers (FC – 235U)
• Exposure of fissionable detectors- irradiation in the central position of ΣΣ-ITN system- fluence > 1014 n/cm2 (2 MW reactor power)- packaging in 0.5mm Al
• Flux monitoring by two monitors fission chambers- in the second vertical channel- in graphite block
• Fission yields measuring by high resolution spectrometry- PTB 408 152Eu calibration point standard source- 5 cm source – crystal distance- SAMPO software package
Characteristics of fissionable detectors
Detector identification
MaterialDetector mass (g)
Isotope mass (g)
Main isotope (%)
Impurities
D2011 238U + 400 ppm 235U 0.534239 0.5342390 ~100.00 238U 400 ppm 235U
D209 Al 10% 239Pu 0.087823 0.0087230 99.95 239Pu 0.05% 240Pu
D204 Al 20% 235U 0.087843 0.0175686 98.00 235U 2.00% 238U
D205 Al 10% 235U 0.087164 0.0087164 98.00 235U 2.00% 238U
D208 Al 5% 239Pu 0.084411 0.0042206 99.95 239Pu 0.05% 241Pu
Note: Mass of alloys are certified by Reactor Experiments USAwith uncertainty of ± 1%.
Results
Fission products
Measured yields
Recommended ENDFB/IVRatio
ΣΣ-ITN / ENDFB/IVΣΣ-ITN CFRMF
95Zr 6.71 ± 3.2% 6.43 ± 2.1% 6.39 ± 1.0% 6.37 1.05
103Ru 3.17 ± 3.2% 3.25 ± 4.2% 3.25 ± 1.5% 3.28 0.97
140Ba 6.13 ± 3.1% 6.04 ± 1.8% 6.07 ± 1.3% 6.04 1.01
131I 3.46 ± 5.6% 3.32 ± 4.5% 3.16 ± 1.29% 3.25 1.06
Fission yields in ΣΣ spectrum for 235U(n,f)
Fission products
Measured yields
Recommended ENDFB/IVRatio
ΣΣ-ITN / ENDFB/IVΣΣ-ITN CFRMF
95Zr 5.11 ± 4.2% 4.64 ± 2.5% 4.74 ± 1.5% 4.73 1.08103Ru 7.18 ± 4.0% 6.66 ± 4.1% 6.94 ± 2.0% 6.73 1.07140Ba 5.73 ± 3.8% 5.14 ± 2.3% 5.37 ± 1.0% 5.24 1.09
131I – 4.10 ± 4.6% 4.02 ± 2.0% 4.10 –
Fission yields in ΣΣ spectrum for 239Pu(n,f)
Fission products
Measured yields
Recommended ENDFB/IVRatio
ΣΣ-ITN / ENDFB/IVΣΣ-ITN CFRMF
95Zr 5.29 ± 4.1% 5.13 ± 2.0% 5.19 ± 2.5% 5.29 1.00103Ru 5.79 ± 3.7% 6.36 ± 2.4% 6.32 ± 4.3% 6.32 0.92140Ba 6.06 5.96 ± 1.5% 5.98 ± 3.8% 6.04 1.00
131I 3.41 ± 5.4% 3.20 ± 1.6% 3.24 ± 4.7% 3.24 1.05
Fission yields in ΣΣ spectrum for 238U(n,f)