neutron generation in the u/pb assembly using 2.52 … b.pdf(incineration) facility. a high power...

NEUTRON GENERATION IN THE U/PB ASSEMBLY NEUTRON GENERATION IN THE U/PB ASSEMBLY USING 2.52 GEV DEUTERON BEAM FROM USING 2.52 GEV DEUTERON BEAM FROM

NUCLOTRONNUCLOTRONPresenter: Igor Zhuk [email protected] Institute for Power and Nuclear Research,

220109, Minsk, Belarus

Co-authors

A.S. Potapenko, A.A. Safronova, Joint Institute of Power and Nuclear Research, 220109 Minsk, Belarus.S.R. Hashemi-Nezhad, School of Physics, A28, University of Sydney, NSW 2006, Australia.V. Wagner,Nuclear Physics Institute of AS CR, CZ-25068 Řež,, Czech Republic.M.I. Krivopustov,Joint Institute of Nuclear Research, 141980 Dubna, Russia.V.А Voronko, V.V. SotnikovNational Scientific Center Kharkov Institute of Physics and Technology NASU, 61108 Kharkov,Ukraine

OUTLINE OUTLINE

• Nuclear waste transmutation using neutron (brief introduction)

• Collaboration “Energy plus Transmutation”Membershipproject “Energy plus Transmutation”

• ExperimentExperimental instruments

accelerator “Nuclotron”experimental subcritical setup

Resultsexperimental resultsMonte Carlo simulationssimulations vs. experiment

IAEA Technical meeting on Application of accelerators in real-time studied of materials

The transmutation of fission products and higher actinides can be effectively done by means of the placement into an intensive neutron field! BUT Even large neutron flux densities in a classical nuclear reactor (typically 10^14 neutronscm−2s−1) are not efficient enough for transmutation purposes. Required flux for ADS should be at least two orders bigger to enable conversion of nuclei with low absorption cross-sections and a few-step capture process in the case of higher actinides. To meet such requirements, the spallation reactions on a thick target can be used as an intensive source of neutrons

Pictorial representation of high energy proton interaction with target nucleolus. In the fist stage the incident particle interacts of with individual nucleons [Intranuclear cascade (INC) phase]. This is followed by intermediate stage (pre-equilibrium). In both of these stages high energy light particles (dominated by neutrons) are emitted which then interact with other nuclei in the extended target (internuclear cascade). In the second stage the residual nucleus either undergoes evaporation releasing neutrons and light ions (with energies around 1 MeV) or fission. In the final stage the residual nucleus (or nuclei) de-excite via gamma emission.IAEA Technical meeting on Application of accelerators in real-

time studied of materials

An Accelerator Driven System equipped with a long-lived fission product transmutation(incineration) facility. A high power proton accelerator is coupled to the subcritical assembly producing spallation neutrons in the lead target which sustain the chainreaction in the core. The fuel rods are made of mixed oxides of thorium and U-233 (or plutonium and minor actinides from the nuclear waste of the conventional reactors). The reactor core and target are embedded within an environment that acts as neutron and heat storage medium as well as the neutron moderator. We will refer to this medium as M-medium

Intense neutron fields could be produced in the interaction of high-energy protons (or ions) with heavy target materials via spallation reactions. Sub-critical accelerator driven system (ADS) can be used for future nuclear energy production and long-lived radioactive nuclear waste transmutation


Collaboration “Energy plus Transmutation”Collaboration exists in Joint Institute for Nuclear

Research (in Dubna, Russian Federation) since 1997

LABORATORYOF HIGH ENERGY PHYSICS,Building of the accelerator ring

Layout of the Accelerator Centre


MembershipAt the moment, scientists from the following research institutes and countries are taking part in the collaboration:

1. Joint Institute for Nuclear Research, Dubna, Russia2. Aristotle University, Thessaloniki, Greece3. Institute of Nuclear Sciences,Vinca, Belgrad, Serbia4. Nuclear Physics Institute, Rez near Praha , Czech Republic5. Joint Institute of Power and Nuclear Research, Sosny, Minsk, Belarus6. University, Department of High Energy Physics, Sydney, Australia7. Stepanov Institute of Physics, Minsk, Belarus8. Philipps-Universität, Marburg, Germany9. Institute of Atomic Energy, Otwock-Swierk near Warzhawa, Poland10. Kharkov Institute of Physics and Technology, Kharkov, Ukraine11. Technical University, Darmstadt, Germany12. Czech Technical University in Prague, Czech Republic13. Institute of Physics and Technology NASK, Almaty, Republic Kazakhstan14. University of Rajasthan, Jaipur, India15. National University, Ulan-Bator, Mongolia16. Bhabha Atomic Research Centre, Mumbai, India


“Background” of the Project “Energy plus Transmutation” in JINR

� 1963-69, Investigation of neutron multiplicity in massive targets from metallic Uranium under proton irradiations (energy range 0.3-0.66 GeV) Vasillkov et

al.� 1965-68, Investigation of neutron multiplicity and neutron yields in massive Lead targets under proton irradiations (energy range 0.3-0.66 GeV) Vasillkov et al.� 1979-84, Investigation of neutron multiplicity and neutron yields in massive Lead targets under proton irradiations (energy range 0.8-8.1 GeV) Vasillkov et al.� 1987-92, Investigation of neutron generation and transport in massive Lead targets

50×50×80 cm3 under charged particle (protons, alpha-particles, deuterons, 12C ions) irradiations (energy range 3.6-8.1 GeV) – project “Energy” - Tolstov et al.

Project “Energy plus Transmutation” within the framework of research program “Investigations of physical aspect of electronuclear energy generation and atomic reactors radioactivewaste transmutation using high energy beams of synchrophasotron/nuclotron JINR (Dubna)”


The project “Energy plus Transmutation” what for…

During 1999-2004 various experiments were made with “Energy plus Transmutation”assembly employing proton beams with kinetic energies in the range from 0.7 GeV to 2.0 GeV. The experiments were focused on general aspects of energy generation by futureAccelerator Driven Systems (ADS), such as:

� Neutron generation and multiplication � Neutron spectra determination (division into thermal, resonance, fast and high-energy groups)� Generation of secondary isotopes inside the Pb-target and U-blanket � Energy generation and deposition� Neutron induced transmutation of:

1. long-lived minor-actinides (237Np and 241Am),2. fission products (129I)3. Plutonium isotopes (238Pu and 239Pu).

XeI),n(I 130h36,12T;*130129 2/1 →γ =β−

),(129 nxnI →),(129 xnypnI

*238d2,2T;238237 PuNp),n(Np 2/1 →γ =β−

→),(239,238 fnPu

(stable)

stable and radioactive isotopes

(T1/2=87.74 y)

fission products

and


Project “Energy plus Transmutation”

The project is included in the TOPICAL PLAN

FOR JINR RESEARCHAND INTERNATIONAL COOPERATION

IN 2008

Within the framework of the theme 03-1-0983-92/2008

Study of Multiple Production in 4 π -geometry. Experiments at the Nuclotron


Nuclotron: beam parameters


Parameter Project RealAccelerated particle 1

Nuclotron: plans for futureThe projected construction of the booster could enable to increase the intensity of the accelerated beams from the present value 3 1010 particles per cycle by a few orders of magnitude(see: Smirnov A. A., Kovalenko A. D. Nuclotron -Superconducting Nuclei Accelerator at LHE, JINR (Design, Operation and Development), Particles and Nuclei, Letters 6 (2004) 11-40 (in Russian))


Nuclotron: how it’s looks

Nuclotron ring and operating console of the Nuclotron

Nuclotron superconducting magnets. Dipole magnet (left) is anchored in the vacuum shell of the cryostat by eight parts of a stainless steel (m = 500 kg, l = 1462 mm, B = 2 T). Quadrupole magnet (right), m = 200 kg, l = 450 mm, grad B = 33.4 T/m

Experimental setup

1) Cylindrical lead targets with diameter 8.4 cm and length 45.6 cm.2) A natural uranium blanket surrounds the target. In the experiment these blanket sections were located one after another; the front of the first blanket sectionand the front face of the lead target were in the same plane. Blanket sections consist of uranium rods (metal natural uranium packed into aluminum cladding), with diameter 3.6 cm, length 10.4 cm and weight 1720g. Each blanket section contains 30 uranium rods with weight 51.6 kg. Thus the 4 blanket sections contain 120 uraniumrods with total weight 206.4 kg. There is a 0.8 cm gap between the blanket sections to be used for detectors.3) The whole target-blanket system was placed within a wooden container filled with granulated polyethylene. The inner walls of the container were covered with a Cd foil of thickness 1 mm.


Target + blanket assembly

Scheme of the four-section “Energy plus Transmutation” setup with a massive lead target and uranium subcritical blanket. The placement of transmutation samples in presented at the surface of the second section of U-banket.


Haw it’s looks

Subcritical assembly + biological shielding


Techniques

Measured value: reaction rates• Natural Uranium fission • capture [238U(n,γ)]• Natural Lead fission

Experimental techniques• Solid nuclear track detectors (SSNTD)

(total fission reaction rates measurement)• Standard activation method (γ-spectrometry)

(neutron induced fission reaction rates measurement; capture reaction rates measurement)


Sensors location

(a) The schematic drawing of the fission-foil-track-detector assembly used in the experiments. (b) Schematic drawings of the sample plates and natU-mica detector sandwiches used in the experiment and(c) placement of the sample plate within EPT assembly. Each target section is 114 mm long and there is a gap of 8 mm between each pair of target-blanket sections.


Beam focusing on the target

The setup can be moved to the irradiation place at focus F3N of the Nuclotron experimental complex using a special rail system

Before the irradiation a target was carefully adjusted concerning a direction of a Nuclotron beam using polaroid films, i.e. the longitudinal axis of a target was combined with a direction of a Nuclotron beam. The traces of one bunch of beam particles on polaroid film placed in front of the target


Beam parameters: intensity

The intensity profile of the irradiation of the Pb-target with U-blanket at 2.52 GeV deuteron beam, as delivered by the Nuclotron.


Beam parameters: profileThe parameters of the deuteron beam were determined using the NatPb-mica samples in the sample plate that was placed in front of the lead target. On this plate 37 samples were placed along the X- and Y-axes in the interval of -13.5 to 13.5 cm in both cases.

The structure (profile) of the 1.26 GeV/nucleon deuteron beam. 1.(left) The large circle shows the lead target area. The small ellipse and large ellipses show the areas within which 68% and 95% of the incident deuterons strike the target. 2. (right) 3D track density distribution of the deuteron induced fission in natural lead in the XY plane (target surface).


Beam parametersThe beam profiles obtained using NatPb(p, f) reaction and mica track detector.The proton beam fluence was determined using 27Al(d, 3p2n)24Na reaction.

Deuteron energy(GeV)

FWHM of the distributions (cm)

Beam centre coordinates(cm) Total beam

fluenceX-direction Y-direction Xc Yc

2.52 1.5 1.5 1.5 -0.3 (5.9 ± 0.04)× 1012


Experiment: 238U fission rate

1. The fission rate - describes fast part of neutron spectra (with the energy higher fission threshold of 238-U 1.5 MeV) in the experimental setup.

2. The fission rate was measured using two methods: Activation and SSNTD technique

3. All data are in good agreement (except region near the axis of the setup )

dEEER UfUf )()(

5.1

238238 ϕσ∫∞=


Experiment: two independent experimental methods for uranium fission rates determination

0 40 80 1201E-15

1E-14

1E-13

1E-12

0 40 80 1201E-14

1E-13

1E-12

0 40 80 1201E-14

1E-13

1E-12

0 40 80 1201E-14

1E-13

1E-12

0 40 80 120

1E-14

1E-13

U238

fissio

n rate

, [1/nu

clei]

R, mm R, mm

SSNTD ACTIVATION

R, mm

U238

fissio

n rate

, [1/nu

clei]

R, mm R, mm

Radial distributions of 238U fission rates inside the Pb-target and U-blanket for the five detector plates. R is the radial distance from the axis of the lead target. Lines are drawn to guide the eyes.

Note that the vertical scale ranges are not the samefor all plots. Maximum isSituated on thethird plata


Experiment: natural lead fission track densities(SSNTD technique)

0 100 200 300 400 5000

20000

40000

60000

80000

100000

120000

140000 Pb

fissio

n trac

k den

sities

( trac

k/cm2

)

Axial distance, mm

R=20mm R=30mm R=40mm

Experimental distribution of Pb fission track densities in the lead target

0 100 200 300 400 5000

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

Experimental distribution of Pb fission track densities in the uranium blanket

Pb fis

sion t

rack d

ensit

ies ( t

rack/c

m2 )

Axial distance, mm

R=50mm R=60mm R=85mm R=110mm

Axial distributions of track densities for natural lead inside the Pb-target

Axial distributions of track densities for natural lead in the Uranium blanket

Maximum of natural lead track densities distributions for lead target and uranium blanket is on the third plate (axial distance from the top of the target is 228 mm)

The fission of natPb is a threshold reaction - neutron induced fission cross-section becomes significant at neutron energies of greater than ~30 MeV. The fission rate describes ultra-fast part of neutron spectra in the experimental setup.


Experiment: 239Pu accumulationThe procedure of combining the track counting and gamma-spectrometry techniques forthe determination of spectral indices is a new development. It involves reception of informationfrom the same sample by SSNTD-methods, i.e. counting the fission tracks of 238U, and by γ-rayspectrometry methods, i.e. counting a γ-line from the nuclide 239Np at 277.6 keV.

→ → → ===−− yTdTT PuNpUnU 42/12/12/1 10.41,2;*23936,2;*239min4,23;*239238 ),( αββγ


Experiment: capture and fissionThe spectral index (ratio of reaction rates) characterizes a ratio between average cross-sections of neutron capture and neutron induced fission in the uranium blanket -

σσU

fU

capt238238

Neutron capture begin to prevail with increasing radial distance, probably because neutrons are moderated by inelastic collisions with nuclei of the blanket material.A difference (1.5 times) is observed at the periphery of the assembly. This shows the underestimation in calculations of the influence of neutrons moderated in and reflected by the biological shielding.

0 20 40 60 80 100 120 1400 ,0

0 ,5

1 ,0

1 ,5

2 ,0

2 ,5

SI ca

pt 23

8U/fis

s 238

U

R , m m

E x p e rim e n t C a lc u la tio n

spectral indexes are the best for comparison with Monte Carlo simulation: uncertainty in the number of primary particles are rejected

Radial distribution of a spectral index for the second plata (Z=118 mm)


Simulations: codes

Codes : MCNPX - version - 2.6C [calculation was made byS.R. Hashemi-Nezhad, University of Sydney, Australia]FLUKA - version - 2006.3b [calculation was made byA.S. Potapenko, JIPNR, Belarus]

From the real view …to the geometrical module for Monte Carlo codes…


Simulations: FLUKA resultsNeutron spatial distribution: slice yz(the first section and shielding were removed for the best view)

Neutron spectrum for points:Z=118 mm, R=0 mm (red line)Z=118 mm, R=85 mm (green line)

Normalized on the primary particles


Simulations: comparison FLUKA and SSNTD data

Experimental results are in good agreement with calculation in the“blanket region” (radial distances R>4.2 cm)of the setup. It can be explained byoverwhelming contribution of neutron induced fission reaction in the totaluranium fission process

Note that the calculationIncludes only neutron inducedfission

Natural Uranium fission rates:Experimental and calculated results

Radial distributions for Experimental plates No 2 and 4


Simulations: comparison MCNPX and SSNTD data

0 40 80 1200.0

0.1

0.2

0.3

0 40 80 1200.00

0.05

0.10

0.15

0 40 80 1200.00

0.02

0.04

0.06

0.08

0 40 80 1200.00

0.01

0.02

0.03

0.04

0 40 80 1200.00

0.05

0.10

0.15

0.20

Experiment Calculation

Plate 1 Plate 2

x 10-13x 10-12

x 10-12x 10-12

x 10-12

Plate 3

Radial distance, mm

Radial distance, mm

Plate 4

Fissio

n / at

om / (

5.9E+

12 2

.52Ge

V deu

teron

)

Plate 5

Radial distributions of 238U fission rates inside the Pb-target and U-blanket for the five detector plates.R is the radial distance from the axis of the lead target. Lines are drawn to guide the eyes.

Experimental results are in good agreement (within the experimental error interval) with calculation in the “blanket region” (radial distances R>4.2 cm)of the setup.

Natural Uranium fission rates: Experimental and calculated results


1. The structure primary deuterons beam was investigated using SSNTD technique.

2. Experimental radial and axial distributions of fission rates natural Uranium were measured by two independent methods

3. The procedure of combining the track counting and γ-spectrometry techniques for the determination of spectral indices is a new development.

4. Comparison of experimental data with the calculation results obtained with using of computer codes MCNPX 2.6 and FLUKA were carried out.

5. The developed technique allows to determine 239Pu accumulation in the blanket of U/Pb-assembly.

6. It is shown that proton, pion, photon and deuteron induced fissions contribute significantly to the total fission-rate in the samples within the target volume and its immediate vicinity.


We would like to thankVeksler and Baldin Laboratory of High Energies (VBLHE), Joint Institute for Nuclear Research (JINR), Dubna, Russia and staff of the Nuclotron accelerator for providing us the research facilities used in these experiments.

JINR for the hospitality during their stay in Dubna.

National academy of science of Belarus for support this work


THANK THANK YOUYOU


neutron generation in the u/pb assembly using 2.52 … b.pdf(incineration) facility. a high power...

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