The XXII International Baldin Seminar on High Energy Physics Problems "Relativistic Nuclear Physics and Quantum Chromodynamics September 15-20, 2014

Transcription

1 "Relativistic Nuclear Physics and Quantum Chromodynamics September 15-20, 2014 Determination o the ratios o the average plutonium-239 and neptunium-237 ission crosssections to the average uranium-235 ission crosssection in the assembly QUINTA neutron ield Krystsina Husak 1, V.Bukhal 1, I.Zhuk 1, P. Zhivkov 2, S. Tyutyunnikov 3, A. Baldin 3, M. Artiushenko 4, V. Voronko 4, V. Sotnikov 4 1

2 Participants: Joint Institute or Power and Nuclear Research- Sosny, Minsk, Belarus Institute o Nuclear Research and Nuclear Energy o Bulgarian Academy o Sciences, Soia, Bulgaria Joint nstitute or Nuclear Research, Dubna, Russian Federation National Science Center Kharkov Institute o Physics and Technology, NAS o Ukraine 2

3 Accumulation and burning o plutonium, neptunium and other isotopes occur on the installation. It has an eect on the balance o neutrons. These causes make or interest to carry out such measurements. Experiments objectives: determination o the ratio o the average 239 Pu ission cross-section to the average 235 U ission cross-section in the assembly QUINTA neutron ield determination o the ratio o the average 237 Np ission cross-section to the average 235 U ission cross-section in the assembly QUINTA neutron ield 3

4 Target assembly description 4

5 Experimental details_1 The method o the SSNTD was chosen or the determination o the ratios o the average 239 Pu and 237 Np ission cross-sections to the average 235 U ission cross-section. This technique was developed by I. Zhuk and A. Malikhin. It was applied or ission reactions rates measurements in reactor systems RUN December 2013 QUINTA was irradiated o by deuterons (2 GeV/A and 4 GeV/A) o and carbon ions (2 GeV/A and 4 GeV/A) 5

6 Experimental details_2 SSNTD-sensors consist o two parts: o the target-oil that interacts with incident particles via nuclear ission (irradiator) and o the material in which ission ragments leave tracks (track detector). The detectors material was artiicial mica. We are placed sensors on backplate o let side on lead blanket o QUINTA. 6

7 Experimental technique_1 The procedure o the determination o the ratios o the average issionable nuclides cross-sections to the average 235 U ission cross-sections is based on correlation between the track density on a track detector N i, which irradiated in contact with target, and energy neutron lux density o investigated neutron ield φ E : (1) where A i k-number o charged particles produced in k -reaction o i -nuclide; μ i -the raction o charged particles reaching the detector; ε i -detection eiciency o the charged particle track detectors; t -duration o sensors the exposure, sec; d i -the radiator thickness, cm; ρ i -nuclear density o i -nuclide in the radiator, nuclei/сm 3 ; σ i k -microscopic cross-section o k -reaction on i - nuclide. 7

8 Experimental technique_2 (1) The average cross-section o k -reaction on i -nuclide is equal to Then the ratio o average cross sections is the ratio o reaction rates o these nuclides spectral indices (2) The spectral indices are experimental values which are most accurate and easy-to-use or comparison with the simulation results. Because they don t contain the error which is associated with the uncertainty o the luence o the primary particles. 8

9 Experimental technique_3 Absolute and relative methods are used or the determination o the ratios o the average cross-sections. Equations (1) and (2) are used or absolute methods. But absolute methods has a additional uncertainties rom determination o ε, ρ, d uncertainties. In relative methods ε, ρ, d are determined rom calibration measurements in standard neutron ield. So equation or the ratio o average issionable nuclides crosssections is where m and s are the results rom investigated and standard neutron ields. We denoted and Then we obtain ollowing ratio: 9

10 Experimental technique_4 For calculation the ratio o the average 238 U ission cross-section to the average 235 U ission cross-section ormula is used: 1 Uест Uест b a b a U 6.5 U

11 Experimental technique_5 For calculation the ratio o the average 237 Np and 232 Th ission cross-section to the average 235 U ission cross-section ormula is used: i b a i ( ( ) 14 ) 14 (1 (1 U 6.5 U 6.5 U 6.5 U 6.5 ) ) и 14 11

12 Experimental technique_6 For calculation the ratio o the average 239 Pu ission cross-section to the average 235 U ission cross-section ormula is used: 239Pu b a 239Pu 0 0 g g 239Pu 0 0 ( U ( 235 U 6.5 U ) и ) 12

13 Results_1 This part includes measured results o the ratios o the average 239 Pu, 237 Np, 232 Th and 238 U ission crosssections to the average 235 U ission cross-section. Moreover, comparison o the experimental data with results o calculations are presented. The calculations were done by Petar Zhivkov. The calculations perormed with the computer code MCNPX 2.7e with energy neutron data library ENDF70, JANIS 4.0 database, models ISABEL, INCL4/ABLA, CEM2K. 13

14 Results_2 Deuterons 2 GeV/A Deuterons 4 GeV/A Carbon ions 2 GeV/A Carbon ions 4 GeV/A 239 Pu/ 235 U 0,041±0,010 0,040±0,010 0,041±0,010 0,042±0, Np/ 235 U 1,17±0,14 1,17±0,14 1,16±0,14 1,07±0, U/ 235 U 0,35±0,04 0,35±0,04 0,34±0,04 0,35±0, Th/ 235 U 0,0119±0,0014 0,0116±0,0014 0,0126±0,0015 0,0117±0,0014 Measurement uncertainty is estimated by the international standard ISO / IEC 17025:

15 Results_3 Deuterons 2 GeV/A Deuterons 4 GeV/A Carbon ions 2 GeV/A Carbon ions 4 GeV/A Exp Calc Exp Calc Exp Calc Exp Calc 239 Pu / 235 U 0,041 ±0,010 0,040 0,040 ±0,010 0,048 0,041 ±0,010 0,051 0,042 ±0,010 0, Np / 235 U 1,17 ±0,14 1,17 1,17 ±0,14 1,17 1,16 ±0,14 1,17 1,07 ±0,13 1, U/ 235 U 0,35 ±0,04 0,38 0,35 ±0,04 0,38 0,34 ±0,04 0,39 0,35 ±0,04 0, Th / 235 U 0,0119 ±0,0014 0,0123 0,0116 ±0,0014 0,0123 0,0126 ±0,0015 0,0133 0,0117 ±0,0014 0,

16 Conclusions We obtain the ratios o the average plutonium-239, neptunium-237, thorium-232, uranium-238 ission crosssections to the average uranium-235 ission cross-section in the assembly QUINTA neutron ield. Assembly was irradiated by deuterons and carbon ions with energies 2 GeV/A and 4 GeV/A. The ratio o average issionable nuclides cross-sections does not depend on type o incident particles and their energies. The experimental data and calculation are in good agreement. 16

17 Thank you! 17