The XII - th International School-Seminar «The Actual Problems of Microworld Physics» Gomel, Belarus, July 22 - August 2, 2013 V. Bukhal 1, K. Husak 1, I. Zhuk 1, A. Safronava 1, T. Korbut 1, S. Tyutyunnikov 2, M. Kadykov 2, W. Furman 2, A. Patapenka 1, V Chilap 3, A. Chinenov 3 1. JINPR-Sosny Belarus, Minsk 2. JINR Russia, Dubna 3. CPTP “Atomenergomash”, Russia, Moscow

 Nuclear waste transmutation using neutrons (brief introduction)  Study of ADS for transmutation  Experiments of the collaboration “EpT”  Experimental subcritical setup Quinta  Solid State Nuclear Track Detectors (SSNTD) for (spatial and energy distribution of neutrons, spatial distribution of fission reaction rates, beam monitoring 2

The total amount of spent fuel in the world ~ tones of heavy metal Waste transmutation Solution 3

The transmutation of fission products and higher actinides can be effectively done by means of the placement into an intensive neutron field One way to obtain intense neutron sources is to use a hybrid sub-critical reactor-accelerator system called Accelerator-Driven System Even large neutron flux densities in a classical nuclear reactor (typically neutrons ∙ cm −2 ∙ s −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 4

In the range of countries studying of ADS for transmutation is included in the national research programs: J-PARC project in Japan RACE project in USA EUROTRANS in EU MYRRHA project in Belgium YALINA-Booster Facility in Belarus Experiments with spallation neutron sources are focused on future transmutation use of the accelerator driven systems: Megawatt Spallation Target Pilot Experiment (Megapie) experiment studied the behavior of a target under extreme thermal and radiation load Transmutation Experimental Facility (TEF) experiment in J-PARC studies behavior of subcritical ADS under various beam conditions Planned project Multi-purpose hybrid research reactor for high-tech applications (MYRRHA) will combine both directions. 5

YALINA-Booster Facility (Joint Institute for Power and Nuclear Research – Sosny, NASB) It is a multizone subcritical assembly driven by an external neutron source: a 252 Cf source or a neutron generator (deuteron accelerator with deuterium or tritium target) Fast zone 1 – U met 90% in lead Fast zone 2 – UO 2 36% in lead Pb target Absorber zone - boron carbide (B 4 C), Nat U Thermal zone – UO 2 10% in polyethylene All surrounded by Graphite Lead subassembly of the fast zone Polyethylene subassembly of the thermal zone 6

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 , Investigation of neutron multiplicity in massive targets from metallic Uranium (m ~ 3 t, 56×56×64 cm 3, from uranium bar 2×4×8 cm 3 ) with 10 cm lead shielding under proton irradiations (energy range GeV) Vasillkov et al.  , Investigation of neutron multiplicity and neutron yields in massive Lead targets (cylinder diameter cm, length 55 cm) under proton irradiations (energy range GeV) Vasillkov et al.  , Investigation of neutron multiplicity and neutron yields in massive Lead targets (cylinder diameter cm, length cm) under proton irradiations (energy range GeV) Vasillkov, Yurevich et al.  , Investigation of neutron generation and transport in massive Lead targets 50×50×80 cm 3 under charged particle (protons, alpha-particles, deuterons, 12 C ions) irradiations (energy range GeV) – project “Energy” - Tolstov et al. The end of 1990s - project “Energy plus Transmutation” (EpT) within the framework of research program “Investigations of physical aspect of electronuclear energy generation and atomic reactors radioactive waste transmutation using high energy beams of synchrophasotron/nuclotron JINR (Dubna)” 8

At the moment, scientists from the following research institutes and countries are taking part in the collaboration: Joint Institute for Nuclear Research, Dubna, Russia 1. Aristotle University, Thessaloniki, Greece 2. Institute of Nuclear Sciences,Vinca, Belgrad, Serbia 3. Nuclear Physics Institute, Rez near Praha, Czech Republic 4. Joint Institute of Power and Nuclear Research, Sosny, Minsk, Belarus 5. University, Department of High Energy Physics, Sydney, Australia 6. Stepanov Institute of Physics, Minsk, Belarus 7. Philipps-Universität, Marburg, Germany 8. Institute of Atomic Energy, Otwock-Swierk near Warzhawa, Poland 9. Kharkov Institute of Physics and Technology, Kharkov, Ukraine 10. Technical University, Darmstadt, Germany 11. Czech Technical University in Prague, Czech Republic 12. Institute of Physics and Technology NASK, Almaty, Republic Kazakhstan 13. University of Rajasthan, Jaipur, India 14. National University, Ulan-Bator, Mongolia 15. Bhabha Atomic Research Centre, Mumbai, India 9

Assemblies of the collaboration “Energy plus Transmutation”:  Lead targets + paraffin moderator (Gamma-2). The leaders: M. Krivopustov, R. Brandt  Energy plus Transmutation setup The leader: M. Krivopustov  Lead targets + graphite moderator (Gamma-MD). The leaders: M. Krivopustov, S. Tyutyunnikov, M. Kadykov Since 2009 the collaboration has been renamed to “Energy and Transmutation of Radioactive Waste” (E&T RAW)  Natural uranium target + lead shielding (QUINTA) The leaders: S. Tyutyunnikov, M. Kadykov Future project:  Large Uranium target (19,5 t) The leaders: S. Tyutyunnikov, M. Kadykov 10

The main goals of (E&T RAW) project are to study the basis characteristics of neutron fields inside deep subcritical quasi-infinite AC made of depleted uranium metal, the spatial distributions of core nuclei fission, the production of 239 Pu nuclei, the transmutation reaction rates of long lived minor actinides and fission products as well as to define optimal energy of incident beam for transmutation RAW and energy production All RNT engineering problems including creation of necessary accelerator have to be discussed practically after detailed study and verification of basic physics ideas of proposed approach. At JINR there are very favorable conditions to investigate such type of ADS. There is the suitable accelerator NUCLOTRON with deuteron and proton beams to energy of 5 GeV per nucleon. Beside that there is available the extended natural uranium metal target assembly QUINTA and the quasi-infinite depleted uranium metal target setup (19.5t, 120cm x 100cm) 11

An essentially new scheme of the electronuclear method based on relativistic nuclear technology (RNT) is considered. This is based on the use of the neutron spectrum forming in the deep subcritical active core, much harder than created in chain fission process Main physical idea of RNT approach is: - to use deep subcritical and quasi-infinite (with negligible neutron leakage) multiplying target of natural (depleted) uranium or thorium; - to use proton or deuteron incident beam with (5 – 10) GeV Such ADS can provide extremely hard neutron spectrum within the active core and ensure an effective burning of core material as well as spent nuclear fuel added to the initial core without its preliminary radiochemical reprocessing It is expected that such a spectrum would permit one to burn for energy production natural (depleted) uranium or thorium and simultaneously utilize the long-lived components of spent nuclear fuel of nuclear power plants 12

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Scheme of Pb-target without moderator 14

Scheme of Pb-target with paraffin moderator of 6 cm thickness 15

Scheme of U/Pb-target with paraffin moderator 16

17 Scheme of massive lead target Experiments aimed at the research of the spallation neutron generation process

Scheme of U/Pb setup "Energy plus Transmutation” consist of 2 sections 1,5 GeV Proton beam Текстолит 30 мм Полиэтилен  = 0,7 г/cm3 Кадмий d=1 мм U-blanket Стеклотекстолит d=3 мм Pb-target wood 18 Front viewCross-sectional side view

Scheme of U/Pb setup "Energy plus Transmutation” consist of 3 sections Front viewCross-sectional side view 19 Lead protection Blanket Detectors plate b) Lead protection Blanket Deuteron beam b)

Scheme of U/Pb setup "Energy plus Transmutation” consist of 4 sections 20

Set up with cylindrical lead target and big graphite moderator 21

The uranium target QUINTA simulates the central part of a quasi infinite active core RNT-reactor with the negligible small leaking neutron - 4 identical sections - each section: - 61 cylindrical blocks (d=36 mm, l = 104 mm) of metallic natural uranium sealed in aluminum housing - total mass of uranium kg - front section has the cylindrical input beam channel diameter 80 mm - total mass of uranium in the target assembly is close to 500 kg m target ~ 540 kg 22

To prevent the free passage of the some part of incident beam through the horizontal space between the tightly packed uranium cylinder an axis of the target assembly set with the rotation of 2 degrees with respect to the beam axis Top viewInput beam window 23

In experiments of December 2011 and March 2012 there was added to the uranium target the lead blanket thickness of 10 cm with the input beam window size of the 150x150 mm Cross cut 24

The science of SSNT detectors was born in 1958 when D.A. Young discovered the first tracks in a crystal of LiF The etch pits, later called «tracks», were found in a LiF crystal which was previously placed in contact with a uranium foil, irradiated with slow neutrons and treated with a chemically aggressive solution The damaged regions constituted more chemically active zones than the surrounding undamaged areas In 1959 Silk and Barnes reported the finding of damaged regions in mica. They used the transmission electron microscope to investigate tracks of heavy charged particles in mica Detectors after etching Under an optical microscope Cross-section of a foil-mica detector sandwich 25

SSNTD technique is based on relation of tracks density and flux density of investigated neutron field Track detector with fission foil (source of fission fragment) is irradiated in neutron field. After this the tracks are formed on the track detector surface Sensor sensitivity coefficient: The technique was developed by I. Zhuk and A. Malikhin was applied in fission reactions rate measurements in reactor systems Track detectors fission foil Sensor 26

 Studying spatial distributions of fission reactions in the setup volume (neutron-physical characteristics)  Determination of the primary beam parameters:  Beam position on the target  Beam shape  Beam intensity 27

Detectors plate Track detectors R=0 R=120 R=40 R=80 R=-80 Each plate locates between sections Spatial distributions of 238 U fission and radioactive capture reactions and 239 Pu accumulation are obtained by integrating the measured parameters over the setup volume 28

For adequate experimental results evaluation it is necessary to take account of the precise experiment geometry, namely: - beam axis shift relative to the setup main axis, - shape and size of the incident beam. Beam parameters during the irradiation are determined from solid state nuclear track detectors (based on Pb foils) Track detectors are mounted directly to the front of the QUINTA setup In detail all obtained results are in the next reports 29

The basic simplicity of its methodology The low cost of its materials The great universality of its possible applications The compact geometry of the detectors Their ability in certain cases to preserve their track record for almost infinite length of time They do not need any electronic/electric instrumentation; they can be deployed under field conditions and in remote fairly inaccessible places for long durations of time without the need for human intervention or back up except for initial placement and final retrieval Off-line analysis gives an opportunity to use many sensors for precise estimation of approximation function parameters Sensors can be located in any place, even straight on the target 30

Future project:  Large Uranium target (19.5 t, diameter 120 cm, length 100 cm) The leaders: S. Tyutyunnikov, M. Kadykov The results of the previous experiments carried out at JINR demonstrate the validity of basic principles of RNT. Here it is important to note that basic aim of all measurements with this previous targets is to prepare and to test the experimental technique for realization of main research program with Large Uranium target The main goals of (E&T RAW) project are to study the basis characteristics of neutron fields inside deep subcritical quasi-infinite active core made of depleted uranium metal, the spatial distributions of core nuclei fission, the production of 239 Pu nuclei, the transmutation reaction rates of long lived minor actinides and fission products as well as to define optimal energy of incident beam for transmutation RAW and energy production 31

We would like to thank Veksler and Baldin Laboratory of High Energies (VBLHE), Joint Institute for Nuclear Research (JINR), Dubna, Russia and staff of the Nuclotron accelerator for providing us with the research facilities used in these experiments and personally the projects leaders S. Tyutyunnikov and M. Kadykov for the possibility to take part in the experiments JINR for the hospitality during stay in Dubna BSU National science-educational center of particle physics and high-energy physics for organizational and financial support and personally N. Shumeiko National academy of science of Belarus and leaders of JIPNR-Sosny for supporting work in frame of state programs fundamental research 32

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