Czech Technical University in Prague

CZECH TECHNICAL UNIVERSITY IN PRAGUE

ABSTRACT OF PHD THESIS Czech Technical University in Prague Faculty of Nuclear Sciences and Physical Engineering Department of Nuclear Reactors

Ing. Ondřej Svoboda

EXPERIMENTAL STUDY OF NEUTRON PRODUCTION AND TRANSPORT FOR ADTT

Postgradual study program: Application of Natural Sciences Study field: Nuclear Engineering

Abstract of PhD thesis for acquirement of the academic degree “Doctor”, in abbreviation “Ph.D.”

Prague, April 2011

2 3 The dissertation thesis was done in the internal and combined forms of postgradual study at the Department of Nuclear Reactors at the Faculty of Nuclear Sciences and Physical Engineering at Czech Technical University in Prague. Aspirant: Ing. Ondřej Svoboda Department of Nuclear Spectroscopy Nuclear Physics Institute Academy of Sciences of the Czech Republic 250 68 Řež near Prague Supervisor: RNDr. Vladimír Wagner, CSc. Department of Nuclear Spectroscopy Nuclear Physics Institute Academy of Sciences of the Czech Republic 250 68 Řež near Prague

Opponents: Prof. Ing. Zdeněk Janout, CSc. Department of Experimental Physics Institute of Experimental and Applied Physics CTU Prague Horská 3a/22, 128 00 Prague 2

Ing. Miloslav Hron, CSc. Nuclear Research Institute, plc Husinec-Řež, č.p. 130 250 68 Řež

4 The date of the abstract distribution: ......

The thesis defence takes place on ...... at ………. at the Board for PhD Theses Defence in the study field of Nuclear Engineering in the room No...... at the Faculty of Nuclear Sciences and Physical Engineering at Czech Technical University in Prague.

It is possible to acquaint with the thesis at the department for science and research activity at the Faculty of Nuclear Sciences and Physical Engineering at Czech Technical University in Prague, Břehová 7, Prague 1.

prof. Tomáš Čechák, CSc. The head of the Board for PhD Theses Defence in the study field of Nuclear Engineering FNSPE CTU in Prague, Břehová 7, Praha 1 Contents

1. State-of-the-art of spallation research...... 7 1.1. Spallation reaction...... 7 1.2. Usage of spallation reaction...... 8 1.3. Motivation...... 8 2. The aim of the thesis...... 10 3. Methodology...... 11 3.1. Energy plus Transmutation setup...... 11 3.2. High energy neutron measurements in the E+T setup...... 12 3.3. MCNPX simulations...... 12 3.4. Cross-section measurements of used threshold reactions...... 13 4. Results...... 14 4.1. Beam properties during E+T deuteron irradiations...... 14 4.2. Experimental results of E+T deuteron irradiations...... 14 4.3. MCNPX simulation of the E+T deuteron irradiations...... 17 4.4. The (n,xn) cross-section measurements...... 21 5. Conclusion...... 22 Bibliography...... 24 List of author’s publications...... 26 List of co-author’s publications:...... 28 Summary...... 31 Resumé...... 32 1. State-of-the-art of spallation research Spallation reaction as a perspective source of neutrons is studied with increased interest in last decade. These studies are motivated with the need of high neutron fluxes for material research, transmutation of nuclear waste or production of nuclear fuel from thorium. New spallation sources are planed (European Spallation Source) or already commissioned (American Spallation Neutron Source) to fulfill scientist requirements. With advances in accelerator technology Accelerator Driven Systems seems thanks to its high safety and unique properties to be a perspective energy source for future.

1.1. Spallation reaction Spallation reaction is a process, in which a relativistic light ion (proton, deuteron or heavier nuclei) interacts with a massive heavy metal target, resulting in the breakup of the heavy nucleus and in production of wide range of new particles. Substantial parts of these particles are neutrons with relatively high energy. Number of these neutrons depends on the energy and mass of the interacting ion and on the target material. Spallation reaction can be divided into few stages. Spallation starts with the accelerated proton (for example) interacting with the target nucleus of heavy element (e.g. Pb). The proton penetrates the target nucleus, and distributes its energy to the nucleons of the nucleus. This stage is called intranuclear cascade. Target nucleus is afterwards in highly excited state and undergoes a pre-equilibrium emission of particles and photons. Particles are at this stage of process emitted unisotropicaly, most of them in the forward direction. After this emission, energy is in the nucleus uniformly distributed, but the nucleus is still highly excited. Such a nucleus can than disintegrate or massively evaporate particles to lower its energy. Particle production is isotropic at this phase. Neutrons produced in spallation reaction can have a wide range of energies. Highest energy of the neutrons can reach up to the beam energy. At the low energy part of the spectrum number of neutrons decrease significantly under the energy one MeV. Most effective energy for the spallation reaction is 800-1000 MeV, where the neutron production per MeV per particle has its maximum. Most widely used particles for induce the spallation are protons, because proton beams are the most intensive one. Tantalum, wolfram, lead, and bismuth in solid phase are the most common target materials. Liquid targets with lead/bismuth eutectics or mercury were tested at targets with high power load [0].

7 1.2. Usage of spallation reaction The first usage of spallation reaction was proposed in the late 1940’s at the Lawrence Livermore National Laboratory in California, the USA. A subcritical nuclear reactor driven by and external spallation neutron source was studied with the aim of production of fissile material. Origins of the practical usage of spallation reaction can be found in the works C. D. Bowman, who proposed accelerator transmutation of waste (ATW) [0], and C. Rubia, who was the father of the idea of accelerator driven energy production (ADEP) [0]. Nowadays, the main application of the spallation reaction is in material science and related branches. Neutron scattering is namely one of the most effective ways to obtain information on both, the structure and the dynamics of condensed matter. A wide scope of problems, ranging from fundamental to solid state physics and chemistry, and from materials science to biology, medicine and environmental science, can be investigated with neutrons. Aside from the scattering techniques, non-diffractive methods like imaging techniques can also be applied with increasing relevance for industrial applications. World leading countries plane, build or commission their spallation neutron sources. European spallation source (ESS) is in the preconstruction phase with commissioning at 2019 [0], American spallation neutron source (SNS) with the beam power 1.4 MW and current in beam 1.4 mA is already commissioned [0]. In Japan, spallation neutrons are used at Material & Life Science Experimental Facility. China started to build its spallation neutron source at 2010 and India is in the phase of planning. Rising amount of the spent fuel together with the non-proliferation efforts push forward the studies of accelerator driven subcritical reactors and transmutations. Transmutation is, generally said, every reaction, in which the composition of the atom nucleus is changed. A single neutron capture can change a long-lived nuclide to a short-live or stabile, or convert a non-fissile nuclide to a fissile one. Transmutation can be thus used for stabilization of radioactive fission products, conversion and fission of plutonium and minor actinides, or for production of new fuel from thorium. In combination with safe accelerator driven system, which is under all circumstances subcritical and can be switched off with the switch off of the accelerator, this can be an energy source for future yielding from broad public acceptance.

1.3. Motivation Practical usage of accelerator driven systems and transmutation must be forgone by research in various branches. Simple experiments are used to measure the cross-sections of GeV down to MeV, and to study the spallation

8 reaction and high energy neutron transport in more detail. More complex setups verify neutron multiplication, transmutation rates, heat production, long-term stability and overall suitable concepts for future eXperimental Accelerator Driven Systems (XADS). There is also rising motivation towards improving the precision of predictions of the codes used to simulate production and transport of high- energetic spallation products in material. More realistic simulations will help to design more effective spallation neutron sources, subcritical blankets or better radiation shielding. But for code development and improvements, a lot of real experimental data is needed for comparisons and benchmark tests.

9 2. The aim of the thesis My research on the field of accelerator driven systems involves both simple and complex experiments. The simple experiments are represented by the neutron cross-section measurements of the (n,xn) threshold reactions, that can be used for high energy neutron measurements. To the complex experiments belong spallation experiments on the Energy plus Transmutation (E+T) setup. In the E+T setup I have studied high energy neutron field by means of threshold activation detectors. Thesis further develops studies performed within the international project Energy and Transmutation of Radioactive waste (E&T RAW), see e.g. [0], [0], or [0]. Experimental devices are located in Joint Institute for Nuclear Research (JINR) Dubna, Russia. Main tasks of the thesis were to:  prepare, perform and evaluate 1.6 GeV and 2.52 GeV deuteron experiments on the E+T setup,  study and routinely apply spectroscopic corrections needed for data evaluation,  measure beam intensities, positions and shapes and give the results to whole E&T RAW collaboration,  compare experimental results between itself and with previous proton experiments performed on the E+T setup,  MCNPX simulation of the experiment and comparison between experimental and simulated data,  prepare, perform and evaluate cross-section measurements of (n,xn) threshold reactions used for high energy neutron measurements in the E+T setup.

Thesis was written with respect to its possible users from the Energy and Transmutation community as well as to students from Nuclear Physics Institute of the ASCR, who are interested in this field of physics. In the work there are maybe more detail descriptions and examples than it would be necessary for a PhD work, but I tried to present a clear description of all aspects of my work in order to enable easier continuation in these studies. With the constituency of the readers is connected also the choice of used language – I have selected English.

10 3. Methodology 3.1. Energy plus Transmutation setup Energy plus Transmutation setup consists of a cylindrical lead target (diameter 84 mm, total length 480 mm) and a surrounding subcritical uranium blanket (206.4 kg of natural uranium). Target and blanket are divided into four sections. Between the sections there are 8 mm gaps for user’s samples. Each section contains target cylinder 114 mm long and 30 identical natural uranium rods, which are secured in a hexagonal steel container. The front and back of each section are covered with hexagonal aluminum plate 6 mm thick. The four target-blanket sections are mounted along the target axis on a wooden plate, which is moreover covered with 4 mm thick steel sheet. Uranium rods are hermetically encapsulated in aluminum coverage of thickness 1 mm, respectively 2 mm at the bases. Each rod has a outside diameter of 36 mm, a length of 104 mm, and a weight of 1.72 kg. Density of the uranium is considered to be 19.05 g·cm-3.

Figure 1: Cross-sectional side view (left) and front view (right) of the "Energy plus Transmutation" setup. All dimensions are in millimeters. Around the blanket, there is a radiation shielding consisting of a wooden box with cadmium plates and polyethylene ((CH2)n) in the box walls. Wooden box has approximately cubic shape and volume 1 m3. Cadmium plates have

11 thickness of 1 mm and are mounted on the inner walls of the box. Polyethylene has a density 0.8 g·cm-3 and is granulated.

3.2. High energy neutron measurements in the E+T setup I have measured high energy neutron field produced in spallation reactions inside the E+T setup. I used a method of neutron activation analysis – I placed a known amount of chosen isotope into unknown neutron field. Activation samples were made from aluminum, gold, tantalum, indium, cobalt, bismuth, and yttrium foils. Chemical purity of the materials was better than 99.99 %.

Figure 2: Activation materials used in the E+T experiments for study of the high energy neutron field. I used products of (n,xn) threshold reactions in activation materials to study high energy parts of neutron spectrum. Non-threshold (n,) reactions were suitable for neutron multiplicity studies. I have measured irradiated foils on HPGe detectors and I have used DEIMOS32 code [0] to analyze gained gamma spectra. I have studied and routinely used wide set of spectroscopic corrections to correct raw data.

3.3. MCNPX simulations

I have used MCNPX (Monte Carlo N-Particle transport code – eXtended) [0] to calculate various aspects of the E+T experiments. I have worked with the version 2.7.a and combination of models INCL4/ABLA. I have calculated deuteron, proton, neutron, and pion spectra in the volumes representing the foils in E+T setup irradiated by deuteron beams. I have done a manual folding of calculated spectra with cross-sections calculated in TALYS [0] and MCNPX. I have also used MCNPX to determine yields of non-threshold (n,) reactions and the multiplicity of the setup. Last but not least I have studied various spectroscopy problems using

12 MCNPX (HPGe detector response on non-homogenous and non-point-like source, change of the detector efficiency due to the sample dimensions).

3.4. Cross-section measurements of used threshold reactions Almost no experimental cross-section data exist for most of used threshold reactions over 40 MeV or “n” higher than four. I have used quasi- monoenergetic neutron sources at The Svedberg Laboratory (TSL) [0] at Uppsala, Sweden, and at Nuclear Physics Institute (NPI) [0] at Řež. These sources are based on 7Li(p,n)7Be reaction with half of the neutron intensity in the peak with FWHM = 1 MeV (corresponds to the ground state and first excited state at 0.43 MeV in 7Be) and half of intensity in a continuum in lower energies (corresponds to higher excited states, multiple-particle emission etc.). Neutron intensities were up to 5.105 cm-2s-1 at TSL, respectively 108 cm-2s-1 at NPI. I have used the same types of foils as in E+T experiments. I have measured irradiated foils on HPGe detectors and I have used the same evaluation methods as at E+T experiments. I have developed a method for neutron background subtracting - I made a manual folding between neutron spectra and cross-sections calculated in TALYS. Then I have calculated ratio between the isotope production in neutron peak and by the whole neutron spectrum.

13 4. Results From the year 2005 up to now, there were three deuteron irradiations of the E+T setup. Irradiations took place at the Nuclotron accelerator of the JINR Dubna, Russia. Beam energies were 1.6 GeV, 2.52 GeV, and 4 GeV. I have prepared activation samples, placed them into the setup and measured them after the irradiation. I have completely evaluated first two experiments, at the 4 GeV experiment I have done a beam analysis, calibration of the detectors and MCNPX simulations.

4.1. Beam properties during E+T deuteron irradiations I have used 10x10 cm2 Al beam monitor to measure deuteron beams intensity. Cross-section of used 27Al(d,3p2n)24Na reaction is the only one known for deuterons in used energy region. I have tried to use also other observed reactions and I have recalculated their cross-sections from the proton ones according to the method proposed by J. Blocki [0]. I have used square Cu foils placed directly in front of the target to measure beam position and shape. For evaluation I have chosen only those reactions that were not influenced by backscattered neutrons from the spallation target. Using another shapes and positions of Cu foils I have determined the number of beam particles going out of the target and parallelism of the beam to the target axis. Results of my beam measurement were combined with the beam data from other groups and a common report was published for every experiment.

4.2. Experimental results of E+T deuteron irradiations I have observed yields of reactions with threshold from 5 MeV up to 80 MeV. In longitudinal direction yields have their maxima near to the first gap (~12 cm from the target beginning) for all three beam energies. In radial direction the yields of threshold reactions quickly (almost exponentially) decrease. Typical example of the yields of Au isotopes produced during 1.6 GeV deuteron experiment are displayed on Figure 3 and Figure 4. The uncertainty bars in the figures are only from the Gauss fit in the DEIMOS32 and are hardly visible in the logarithmic scale (are only a few percent). Lines in the graphs are to guide reader’s eyes.

14 10-2

198Au 196Au 194Au 192Au 24Na 10-3 ] n o r

e -4 t 10 u e d * g / 1 [ 10-5 d l e i Y

10-7 -5 5 15 25 35 45 Position along the target [cm] Figure 3: Yields of the isotopes produced in Au and Al activation detectors in longitudinal direction, 3 cm over the target axis, 1.6 GeV deuteron experiment.

10-2 198Au 196Au 194Au 192Au 24Na 10-3 ] n o r e t 10-4 u e d * g / 1 [ -5

d 10 l e i Y

10-7 2 4 6 8 10 12 Radial distance from the target axis [cm] Figure 4: Yields of the isotopes produced in Au and Al activation detectors in radial direction, first gap of the E+T setup – 12.2 cm from the target beginning, 1.6 GeV deuteron experiment.

15 Products of non-threshold 197Au(n,)198Au reaction visible in the Figure 3 and Figure 4 are caused by the epithermal and resonance neutrons coming from the biological shielding. Field of epithermal and resonance neutrons inside the biological shielding is disturbed only on the beginning and at the end of the setup due to the holes in the shielding. Using a new form of the water bath method [0] and data from MCNPX calculation, I have determined neutron multiplicity of the E+T setup, see Figure 5.

80 protons - exp 70 ]

- deuterons - exp - Au [

V e 60 deuterons - exp - Ta G

r protons - sim e p

l 50 deuterons - sim c i t r a p 40 m a e b

r 30 e p

r 20 t u e N 10

0 0 1 2 3 4 Beam energy [GeV] Figure 5: Neutron multiplicities for E+T setup normalized per GeV (proton experimental points overtaken from the PhD thesis of A. Krása, [0]).

I compared experimental yields of reactions with different threshold (here e.g. 196Au and 192Au). I have observed a spectrum hardening at the end of the target. Spectrum hardening is specific for the spallation reaction and is caused by different origin of the neutrons. Neutrons with higher energies comes from the intranuclear phase of the spallation reaction and are emitted more forward, in contradiction to the neutrons below 20 MeV, which comes from evaporation and fission phase of the spallation reaction and are emitted isotropicaly. Additional complication of neutron spectrum comes from the high energy fission in uranium blanket and neutron scattering and moderation. Thus, neutron field inside the E+T setup is a complicated mixture of spallation, fission, moderated and back-scattered neutrons. 16 0.4 ] - [

0.3 A 6 9 1 / u A 2 9

x e d n i

0.1 a r t c

3 cm e p 6 cm 0.0 S 8.5 cm 48 36 10.7 cm 24 12 0

Figure 6: Neutron spectra hardening along the target in 1.6 GeV deuteron experiment (ratio between 192Au and 196Au).

4.3. MCNPX simulation of the E+T deuteron irradiations I have used MCNPX to calculate neutron, proton and deuteron spectra inside the setup. In the Figure 7 we can see an example of a neutron spectrum inside the first target cylinder. In this case I have studied dependence between the presence of various parts of E+T setup and produced neutron spectrum. Difference between bare Pb target and target with all constructions (Al and Fe support structures, U-rod cover from Al etc.) is almost negligible, support structures add some more high energy neutrons due to the spallation induced on them by scattered neutrons. Addition of natural uranium causes more neutrons in the region between 1 keV and 1 MeV due to the high energy fission. Biological shielding adds further neutrons to the low energy region bellow 10 keV and also a second maximum of the neutron spectrum around 0.025 eV. Addition of the cadmium layer on the inner walls of the biological shielding suppresses this thermal energy peak. In all cases, a small peak can be seen close to the highest neutron energies. These neutrons come from the deuteron disintegration.

17 figures of experiment/simulation ratios, where these maximum are missing of well the shape yieldcurves).(the simulation describes are maximum these where theratios, in experiment/simulation and of direction, figures radial and longitudinal in both seen be can maximum a yields,where experimental with figures between the comparison the also by confirmed be can This beams. deuteron of case the in precise generally be to seem models INCL4/ABLA the so found, values were ratios experiment/simulation got I set. the e.g. see in one, the foil to close intensive are which most the to it normalized I ratio of the shape the clearly see To determination. intensity beam the on dependant M. by proven displacement, mm (2%). calibration detector spectroscopic corrections (1%) and 5 at 20% uncertainties other uncertainty, DEIMOS32 (up to placement foil 10%), least (at intensity beam from separately are stated the within parallel are ratios experiment/simulation the of Most ratios. experiment/simulation evaluating omitted. are setup the of parts of 1percent. areontheUncertainties level various scale, log-log protons, GeV 2.52 Figure - 1 - 2

10 N u m b e r o f n e u t r o n s [ d e u t e r o n . c m ] 10 10 10 10 - 8 - - - 0 4 6 2 10 7 - 8 : Spectrum of the neutrons in the first target cylinder irradiated with irradiated cylinder target first the in neutrons the of Spectrum : boue vle f te eprmn/iuain rto ae strongly are ratio experiment/simulation the of values Absolute by yields simulated and experimental of results compared I Pb 10 - 6 Pb+const 10 - 4 Pb+U+const Neutron energy [MeV] Figure 10 Figure 18 10 - 2 . No serious differences in the in differences serious No . without Cd

ael n hs PD PhD his in Majerle 10 0

whole E+T 10 2 [0 10 ]), 4 2.5

198Au 196Au 194Au 192Au 24Na

2.0 ] - [

d l e i y

1.5 . m i s

d l e i

. p x E

0.0 2 4 6 8 10 12 Radial distance from the target axis [cm] Figure 8: Ratio between experiment and simulation in radial direction for 2.52 GeV deuteron experiment, Au and Al samples in the first gap.

Summarizing MCNPX results from previous proton experiments we have observed an increasing difference in the radial direction between experiment and simulation for proton energies higher than 1.5 GeV, see Figure 9. For deuteron experiments there is a good agreement for all three measured energies (from 1.6 GeV up to 4 GeV), see Figure 10. This result prefers the hypothesis that in proton experiments the problem is rather in the experimental part than in the simulations.

19 2.5 2.0 GeV 1.5 GeV 1.0 GeV 0.7 GeV

2.0 ] - [ d l e i y

. 1.5 m i s

d l e i y

1.0 . p x e

0.5 194Au

0.0 2 4 6 8 10 12 14 Radial distance from the target axis [cm] Figure 9: Ratio between experiment and simulation for different proton beam energies and 194Au (overtaken from A. Krása [0]). Samples were placed in radial direction in the first gap of the setup.

1.6 GeV 2.52 GeV 4 GeV 2.0 ] - [

d l e i y

. 1.5 m i s

d l e i

. p x E

194Au 0.0 2 4 6 8 10 12 Radial distance from the target axis [cm] Figure 10: Ratio between experiment and simulation for different deuteron beam energies and 194Au. Samples were placed in radial direction in the first gap of the setup.

20 4.4. The (n,xn) cross-section measurements I have studied cross-sections of (n,xn) threshold reactions for totally 11 energies in the energy region 17 - 94 MeV. I have completely evaluated five measurements and at another six I have helped or I have done a partial evaluation. Highest order of measured reaction was (n,10n). I used well-known cross-sections for low threshold reactions to check if I got appropriate results. I made a comparison between the data from EXFOR library [0], results of the calculations I have done in deterministic code TALYS and experimental data from NPI and TSL. For most of the isotopes I observed good agreement. For energies higher than 40 MeV and reactions higher than (n,4n) no data are available in EXFOR (except bismuth). My cross-section data are in this sense unique and I presented them on international conferences (Baldin 2009 [0], ND2010 [0], EFNUDAT meetings [0], [0], AER meetings…) with positive response.

3 EXFOR 2.5 NPI experiments

] TSL experiments n 2 r a b [ TALYS 1.0 n o i

t 1.5 c

e 197 196 s Au(n,2n) Au - s s o

0 0 10 20 30 40 50 60 70 80 90 100 Neutron energy [MeV]

Figure 11: Cross-section values of the 197Au(n,2n)196Au reaction, comparison between EXFOR, TALYS 1.0, my values and data of J. Vrzalová1 (NPI experiment at 30 and 36 MeV).

1 I was a consultant on her diploma work and helped with the data analysis. 21 5. Conclusion

As a member of the international project Energy and Transmutation of Radioactive Waste I have studied production and transport of high energy neutrons in the setup called Energy plus Transmutation. This setup consists of thick, lead target surrounded with natural uranium blanket and polyethylene biological shielding. Setup was irradiated with 1.6 GeV, 2.52 GeV, and 4 GeV deuterons. I prepared foils for all three experiments; I was present during the irradiation and I measured irradiated foils at JASNAPP laboratory of the Joint Institute for Nuclear Research, Dubna, Russia. I have completely evaluated first two experiments. I used neutron activation detectors from Al, Au, Bi, Co In, Ta, and Y in the form of thin foils to measure spatial distribution of the neutrons inside the setup. I have observed threshold (n,xn), (n,p), and (n,) reactions in the samples in order to distinguish energies of the neutrons. Maximum order of these reactions was (n,11n), that means a threshold of ~ 80 MeV. I have observed maximal neutron flux in the first gap of the setup that means 12 cm from the target beginning in longitudinal direction. In radial direction the maximum was in the centre of the target and then it decreased almost exponentially. Spectral indexes showed a hardening of the neutron spectra in longitudinal as well as radial direction. Comparison among deuteron experiments and also with the previous 0.7 GeV experiment with protons resulted in nice dependence between beam type or energy and intensity of the neutron flux inside the setup. Polyethylene biological shielding in combination with non-threshold reactions enabled me to calculate total number of produced neutrons. In the case of deuterons experiments neutron multiplicity was up to 152 ± 16 at 4 GeV irradiation. I have measured deuteron beam properties in detail. I have used Al foil for beam intensity measurement and Cu foils for beam position, profile and direction determination. Results of my beam analysis are used by whole Energy and Transmutation collaboration. I made MCNPX simulations of deuteron experiments and I compared it with experimental data. MCNPX describes relatively well the shape of the neutron distribution in radial and longitudinal directions, however the absolute exp/sim differences are much bigger than they should be at future ADS systems, so a further MCNPX development and benchmark tests are needed. I have not observed any serious discrepancies in the number of neutrons emitted to backward angles like it was observed at previous proton experiments.

22 Further, I obtained unique data about cross-sections of used threshold reactions for neutron energies above 40 MeV. With the support from EFNUDAT I used quasi-monoenergetic 7Li(p,n)7Be neutron source at TSL Uppsala, Sweden. In 2008, I performed three irradiations with neutron energies 22, 47, and 94 MeV. These measurements were supplemented with measurements at NPI Řež with neutron energies 17, 22, 30, and 35 MeV. In the meantime I prepared a proposal on second cross-section measurement at Uppsala and in 2010 I participated on irradiations at neutron energies 59, 66, 73, and 89 MeV. I was involved in all experiments and I analyzed the data completely except the 30 and 35 MeV irradiations at NPI and the second TSL experiment. I have developed a procedure how to subtract the neutron background, which was applied on most of measured cross-sections. Using two different neutron sources and various spectroscopic equipments I got the same results within the uncertainties, so all important sources of uncertainties seems to be under control. I have compared measured cross-sections with the data from EXFOR where possible. I used deterministic code TALYS to calculated neutron cross-sections of all reactions and I compared them with measured data. I have already presented the data discussed in this work on 15 international workshops and conferences. I am co-author of four articles in peer reviewed journals, I am the first author of 11 proceedings (three of them are peer reviewed), one internal report and co-author of another five proceedings and four internal reports.

23 Bibliography

[0] Megawatt Pilot Target Experiment, project web pages http://megapie.web.psi.ch/ (5.1.2011) [0] C.D. Bowman et al.: Nuclear Energy Generation and Waste Transmutation Using an Accelerator-driven Intense Thermal Neutron Source, Nuclear Instruments and Methods in Physics Research, A320 (1992) p. 336- 367 [0] C. Rubbia et al.: Conceptual design of a fast neutron operated high power energy amplifier, European Organization for Nuclear Research/AT/94-44 (ET) [0] European Spallation Source web page, http://ess-scandinavia.eu/ (4.1.2011) [0] Spallation Neutron Source, http://neutrons.ornl.gov/facilities/SNS/ (4.1.2011) [0] J. Adam et al.: Transmutation studies with GAMMA-2 setup using relativistic proton beams of the JINR Nuclotron, Nuclear Instruments and Methods - A, V. 562, Iss. 2 (2006) p. 741-742 [0] W. Westmeier et al.: Transmutation experiments on 129I, 139La and 237Np using the Nuclotron accelerator, Radiochimica Acta, V. 93 (2005) p. 65-73 [0] A. Krása et al.: Neutron production in a Pb/U-setup irradiated with 0.7- 2.5 GeV protons and deuterons, Nuclear Instruments and Methods in Physics Research, Section A, 615 (2010) p. 70-77, ISSN: 0168-9002 [0] J. Frána: Program DEIMOS32 for Gamma-Ray Spectra Evaluation, Journal of Radioanalytical and Nuclear Chemistry, V.257, No. 3 (2003) p. 583-587 [0] MCNPX (Monte Carlo N-Particle eXtended), http://mcnpx.lanl.gov/ (19. 11. 2010) [0] A. J. Koning et al., “TALYS-1.0.”, Proceedings of the International Conference on Nuclear Data for Science and Technology - ND2007, (2007) p. 211-214 [0] A. V. Prokofiev et al.: The TSL Neutron Beam Facility, Radiation Protection Dosimetry, 126 (2007) p. 18-22

24 [0] P. Bém et al.: The NPI cyclotron-based fast neutron facility, Proceedings of the International Conference on Nuclear Data for Science and Technology - ND2007, (2007) p. 555-558 [0] J. Blocki et al.: Proximity forces, Annals of Physics, Vol. 105, Issue 2, (1977) p. 427-462 [0] K. van der Meer et al., Spallation yields of neutrons produced in thick lead/bismuth targets by protons at incident energies of 420 and 590 MeV, Nuclear Instruments and Methods in Physics Research B 217 (2004) p. 202- 220 [0] A. Krása: Neutron Emission in Spallation Reactions of 0.7 – 2.0 GeV Protons on Thick, Lead Target Surrounded by Uranium Blanket, Dissertation Thesis, FJFI – ČVUT, Prague (2008) [0] M. Majerle: Monte Carlo methods in spallation experiments, Dissertation Thesis, FJFI – ČVUT, Prague (2009) [0] A. Krása: personal communication [0] Experimental Nuclear Reaction Data (EXFOR/CSISRS), http://www.nndc.bnl.gov/exfor, (4.12.2010) [0] O. Svoboda et. al.: Measurements of Cross-sections of the Neutron Threshold Reactions and Their Usage in High Energy Neutron Measurements at "Energy plus Transmutation", XIX. International Baldin Seminar on High Energies Physics Problem, Dubna, Russia, September 25 -29 (2008), Relativistic Nuclear Physics and Quantum Chromodynamics series, p. 136 – 141, ISBN: 978-5-9530-0203-5 [0] O. Svoboda et al.: Cross-section Measurements of (n,xn) Threshold Reactions, ND2010 conference, Jeju (2010) South Korea – in print [0] O. Svoboda et al.: Three years of cross-section measurements of (n,xn) threshold reactions at TSL Uppsala and NPI Řež, EFNUDAT user and collaboration workshop „Measurements and Models of Nuclear Reactions“, Paris, France, EPJ Web of Conferences, vol. 8 (2010) p. 7003/1-6, ISBN. 978-2-7598-0585-3 [0] O. Svoboda et al.: Cross-section Measurements of (n,xn) Threshold Reactions in Au, Bi, I, In, and Ta - Proceeding of the 2nd EFNUDAT workshop – Slow and Resonance Neutrons, Special Scientific Issue of Institute of Isotopes – Hungarian Academy of Science, Budapest, Hungary, p. 155-161, ISBN: 978-963-7351-19-8

25 List of author’s publications

 O. Svoboda, J. Adam, Z. Dubnička, A. Krása, A. Kugler, M. I. Krivopustov, M. Majerle, V. M. Tsoupko-Sitnikov, V. Wagner: Setup consisting of a Pb/U assembly irradiated by 2.52 GeV deuterons, Relativistic Nuclear Physics and Quantum Chromodynamics volume 1, (2006) p. 222-227, ISBN: 5-9530-0190-8  O. Svoboda: Produkce neutronů v tříštivých reakcích a jejich využití pro transmutaci radionuklidů, Jaderná energetika v pracích mladé generace – 2006, Sborník 6. Mikulášského setkání sekce mladých při České nukleární společnosti, VÚT Brno (2007) p. 66-70, ISBN: 978-80-02-01883-4  O. Svoboda, A. Krása, F. Křížek, A. Kugler, M. Majerle, V. Wagner, V. Henzl, D. Henzlová, Z. Dubnička, M. Kala, M. Kloc, J. Adam, M. I. Krivopustov, V. M. Tsoupko-Sitnikov: Neutron Production in Pb/U Assembly Irradiated by Protons and Deuterons at 0.7–2.52 GeV, ND2007, Nice (2007) DOI: 10.1051/ndata:07737, p. 1197 - 1200  O. Svoboda, A. Krása, M.Majerle, V. Wagner: Neutron production in Pb/U assembly irradiated by deuterons at 1.6 and 2.52 GeV, NEMEA-4 - Proceedings of the CANDIDE workshop, Prague (2007) p. 87 – 90, ISBN 978-92-79-08274-0,

 O. Svoboda, A. Krása, A. Kugler, M. Majerle, V. Wagner: Cross-section measurements of the (n,xn) threshold reactions, NEMEA-5 - Proceedings of the CANDIDE workshop (2011) p. 103-106, ISBN: 978-92-79-19067- 4

 O. Svoboda, A. Krása, A. Kugler, M. Majerle, V. Wagner: Measurements of cross-sections of neutron threshold reactions and their usage in high energy neutron measurements, recenzovaný sborník 16. konference českých a slovenských fyziků, Hradec Králové (2009), ISBN: 80-86148-93-9  O. Svoboda, A. Krása, M. Majerle, V. Wagner: Study of Neutron Production and Transmutation in ADTT, sborník k IGS workshopu, Prague (2009), ISBN 978-80-01-04286-1  O. Svoboda, A. Krása, M. Majerle, V. Wagner: Measurements of Cross- sections of the Neutron Threshold Reactions and Their Usage in High Energy Neutron Measurements at "Energy plus Transmutation", Relativistic Nuclear Physics and Quantum Chromodynamics series, Dubna (2008), p. 136 – 141, ISBN: 978-5-9530-0203-5

26  O. Svoboda, J. Vrzalová, A. Krása, M. Majerle, V. Wagner: Cross- section Measurements of (n,xn) Threshold Reactions in Au, Bi, I, In, and Ta, - Proceeding of the 2nd EFNUDAT workshop – Slow and Resonance Neutrons, Special Scientific Issue of Institute of Isotopes – Hungarian Academy of Science, Budapest (2009) p. 155-161, ISBN: 978-963-7351- 19-8

 O. Svoboda, J. Vrzalová, A. Krása, M. Majerle, V. Wagner: Cross- section Measurements of (n,xn) Threshold Reactions, ND2010, Jeju (2010) South Korea – accepted, in print

 O. Svoboda, A. Krása, M. Majerle, V. Wagner: Study of Spallation Reaction, Neutron Production and Transport in Thick Lead Target and Uranium Blanket Irradiated with 0.7 GeV Protons, Joint Institute for Nuclear Research – Preprint E15-2009-177

 O. Svoboda, J. Vrzalová, A. Krása, A. Kugler, M. Majerle, V. Wagner: Three years of cross-section measurements of (n,xn) threshold reactions at TSL Uppsala and NPI Řež, EPJ Web of Conferences, vol. 8, Paris, (2010) p. 7003/1-6, ISBN. 978-2-7598-0585-3

27 List of co-author’s publications:  V. Wagner, A. Krása, F. Křížek, A. Kugler, M. Majerle, O. Svoboda, J. Adam, M. I. Krivopustov: Experimental Studies of Spatial Distributions of Neutrons inside and around the Setup Consisted from a Thick Lead Target and a Large Uranium Blanket Irradiated by Relativistic Protons, Relativistic Nuclear Physics and Quantum Chromodynamics, vol. II, Dubna (2005) p. 111-116, ISBN: 5-9530-0055- 3  A. Krása, M. Majerle, F. Křížek, V. Wagner, A. Kugler, O. Svoboda, V. Henzl, D. Henzlová, J. Adam, P. Čaloun, V. G. Kalinnikov, M. I. Krivopustov, V. I. Stegailov, V. M. Tsoupko-Sitnikov: Comparison between experimental data and Monte-Carlo simulations of neutron production in spallation reactions of 0.7-1.5 GeV protons on a thick, lead target, Journal of Physics: Conference Series 41 (2006) p. 306-314  V. Wagner, A. Krása, M. Majerle, F. Křížek, O. Svoboda, A. Kugler, J. Adam, V. M. Tsoupko-Sitnikov, M. I. Krivopustov, I. V. Zhuk, W. Westmeier: The Possibility to Use „Energy plus Transmutation“ Setup for Neutron Production and Transport Benchmark Studies, PRAMANA – Journal of Physics vol. 68 (2007) p. 297-306  M. I. Krivopustov, A. V. Pavliouk, A. D. Kovalenko, I. I. Mariin, A. F. Elishev, J. Adam, A. Kovalik, Yu. A. Batusov, V. G. Kalinnikov, V. B. Brudanin, P. Chaloun, V. M. Tsoupko-Sitnikov, A. A. Solnyshkin, V. I. Stegailov, S. Gerbish, O. Svoboda, Z. Dubnicka, M. Kala, M. Kloc, A. Krasa, A. Kugler, M. Majerle, V. Wagner, R. Brandt, W. Westmeier, H. Robotham, K. Siemon, M. Bielewicz, S. Kilim, M. Szuta, E. Strugalska- Gola, A. Wojeciechowski, S. R. Hashemi-Nezhad, M. Manolopoulou, M. Fragopolou, S. Stoulos, M. Zamani-Valasiadou, S. Jokic, K. Katovsky, O. Schastny, I. V. Zhuk, A. S. Potapenko, A. A. Safronova, Zh. A. Lukashevich, V. A. Voronko, V. V. Sotnikov, V. V. Sidorenko, W. Ensinger, H. D. Severin, S. Batsev, L. Kostov, Kh. Protokhristov, Ch. Stoyanov, O. Yordanov, P. K. Zhivkov, A. V. Kumar, M. Sharma, A. M. Khilmanovich, B. A. Marcinkevich, S. V. Korneev, Ts. Damdinsuren, Ts. Togoo, H. Kumawat and Collaboration “Energy plus Transmutation: About the first experiment on investigation of the 129I, 237Np, 238Pu and 239Pu transmutation at the Nuclotron 2.52 GeV deuteron beam in neutron

field generated in Pb/U-assembly Energy plus Transmutation>>, Dubna Preprint E1-2007-7  V. Wagner, A. Krása, F. Křížek, A. Kugler, M. Majerle, O. Svoboda, Z. Dubnička, J. Adam, M.I. Krivopustov: Spatial distribution of neutrons in the Pb/U assembly irradiated by relativistic protons and deuterons -

28 systematics of experimental results, Relativistic Nuclear Physics and Quantum Chromodynamics vol. 1, Dubna (2006) p. 228-233, ISBN: 5- 9530-0190-8  M. Oden, A. Krása, M. Majerle, O. Svoboda, V. Wagner: Monte-Carlo Simulations: Fluka vs. MCNPX, Nuclear Physics Methods and Accelerators in Biology and Medicine, AIP Conference Proceedings, Prague (2007) p. 958

 V. Wagner, A. Krása, M. Majerle, O. Svoboda: Systematic studies of neutrons produced in the Pb/U assembly irradiated by relativistic protons and deuterons, NEMEA-4 - Proceedings of the CANDIDE workshop, Prague (2007) p. 95 -98, ISBN 978-92-79-08274-0,  M. I. Krivopustov, A. V. Pavliouk, A. D. Kovalenko, I. I. Mariin, A. F. Elishev, J. Adam, A. Kovalik, Yu. A. Batusov, V. G. Kalinnikov, V. B. Brudanin, P. Chaloun, V. M. Tsoupko-Sitnikov, A. A. Solnyshkin, V. I. Stegailov, Sh. Gerbish, O. Svoboda, Z. Dubnicka, M. Kala, M. Kloc, A. Krasa, A. Kugler, M. Majerle, V. Wagner, R. Brandt, W. Westmeier, H. Robotham, K. Siemon, M. Bielewicz, S. Kilim, M. Szuta, E. Strugalska- Gola, A. Wojeciechowski, S. R. Hashemi-Nezhad, M. Manolopoulou, M. Fragopolou, S. Stoulos, M. Zamani-Valasiadou, S. Jokic, K. Katovsky, O. Schastny, I. V. Zhuk, A. S. Potapenko, A. A. Safronova, Zh. A. Lukashevich, V. A. Voronko, V. V. Sotnikov, V. V. Sidorenko, W. Ensinger, H. D. Severin, S. Batsev, L. Kostov, Kh. Protokhristov, Ch. Stoyanov, O. Yordanov, P. K. Zhivkov, A. V. Kumar, M. Sharma, A. M. Khilmanovich, B. A. Marcinkevich, S. V. Korneev, Ts. Damdinsuren, Ts. Togoo, H. Kumawat: First results studying the transmutation of 129I, 237Np, 238Pu, and 239Pu in the irradiation of an extended natU/Pb- assembly with 2.52 GeV deuterons, Journal of Radioanalytical and Nuclear Chemistry, vol. 279 (2009) p. 567-584  A. Krása, V. Wagner, M. Majerle, F. Křížek, A. Kugler, O. Svoboda, J. Adam, M. I. Krivopustov: Neutron production in a Pb/U-setup irradiated with 0.7-2.5 GeV protons and deuterons, Nuclear Instruments and Methods in Physics Research, Section A, vol. 615 (2010) p. 70-77, ISSN: 0168-9002  M. Majerle, J. Adam, A. Krása, S. Peetermans, O. Sláma, Stegailov, O. Svoboda, Tsoupko-Sitnikova, V. Wagner: Monte Carlo method in neutron activation analysis, Joint Institute for Nuclear Research Preprint E11-2009-178  T. Bílý, J. Frýbort, L. Heraltová, O. Huml, O. Svoboda, M. Vinš: Citlivostní analýza MCNP modelu školního reaktoru VR-1 Vrabec, technical report KJR FJFI ČVUT

29  J. Adam A. Baldin, N. Vladimirova, N. Gundorin, B. Guskov, V. Dyachenko, A. Elishev, M. Kadykov, E. Kostyuhov, V. Kransov, I. Marin, V. Pronskikh, A. Rogov, A. Solnyshkin, V. Stegailov, S. Stetsenko, S. Tyutyunikov, V. Furman, V. Tsoupko-Sitnikov, E. Belov, M. Galanin, V. Kolesnikov, N. Ryazansky, S. Solodchenkova, B. Fonarev, V. Chilap, A. Chinenov, E. Baldina, A. Balabekyan, G. Karapetyan, I. Zhuk, S. Korneev, A. Potapenko, A. Safronova, V. N. Sorokin, V. V. Sorokin, A. Khilmanovich, B. Marcynkevich, T. Korbut, Ch. Stoyanov, L. Kostov, P. Zhivkov, O. Yordanov, S. Batzev, Ch. Protohristov, A. Kugler, V. Wagner, M. Majerle, A. Krasa, O. Svoboda, K. Katovsky, O. Schasny, A. Tuleushev, K. Gudima, M. Baznat, R. Togoo, D. Otgonsuren, Ts. Tumendelger, Ts. Damdinsuren, M. Shuta, E. Strugalska-Gola, S. Kilim, M. Bielevicz, A. Wojeciechowsky, V. Voronko, V. Sotnikov, V. Sidorenko, I. Haysak, S. R. Hashemi-Nezhad, Y. Borger, W. Westmeier, H. Robotham, W. Ensinger, D. Severin, M. Rossbah, B. Thomauske, M. Zamani, M. Manolopoulou, St. Stoulos, M. Fragopolou, St. Jokic, H. Kumawat, V. Kumar, M. Sharma („E&R RAW“ collaboration): Study of deep subcritical electronuclear systems and feasibility of their application for energy production and radioactive waste transmutation – Joint Institute for Nuclear Research Preprint Preprint E1-2010-61

30 Summary High energy neutron production in spallation reactions and their transport in the system of massive lead target and uranium blanket were studied within the international project Energy and Transmutation of Radioactive Waste. Setup called Energy plus Transmutation placed in Dubna, Russia, was irradiated with 1.6 GeV up to 4 GeV deuterons. Threshold reactions on activation detectors from Al, Au, Bi, Co, In, Ta, and Y were used for neutron measurements. Activated foils were measured on HPGe detectors. Spectroscopic corrections were applied during data analysis to find the yields of produced isotopes. Experimental results were compared with MCNPX calculations. These experiments are a continuation of previous research of above mentioned setup with relativistic protons. No serious disagreement in neutron production to backward angles was observed for deuteron experiments contrary to proton ones. Cross-sections of used threshold reactions were measured on quasi- monoenergetic neutron sources at Nuclear Physics Institute in Řež and at The Svedberg Laboratory in Uppsala, Sweden. Totally eleven irradiations were done in the energy range 17 – 94 MeV. Threshold reactions were measured up to (n,10n), results were compared with the data from EXFOR, EAF, and with calculated values from TALYS code with good agreement. Cross- sections for reactions over 40 MeV and (n,4n) are unique and were measured for the first time. Part of the data has been already published and presented on international conferences.

31 Resumé Produkce vysokoenergetických neutronů ve spalačních reakcích a jejich transport v systému masivního olověného terče a uranového blanketu byly studovány v rámci mezinárodního projektu „Energy and Transmutation of Radioactive Waste“. Sestava nazvaná „Energy plus Transmutation“ umístěná v Dubně, Rusko, byla ozářena deuterony o energiích 1,6 GeV až 4 GeV. Pro měření neutronů byly použity prahové reakce na aktivačních detektorech z Al, Au, Bi, Co, In, Ta a Y. Aktivované fólie byly měřeny pomocí HPGe detektorů. Při analýze získaných dat byla aplikována řada spektroskopických korekcí za účelem nalezení výtěžku sledovaných isotopů. Experimentální data byla nakonec porovnána s výsledky simulací sestavy v MCNPX. Tyto experimenty navázaly na předchozí výzkum zmíněné sestavy pomocí relativistických protonů. Pro deuteronové experimenty nebyla na rozdíl od protonových pozorována žádná výraznější neshoda v produkci vysokoenergetických neutronů do zpětných úhlů. Účinné průřezy užitých prahových reakcí byly změřeny pomocí quasi-monoenergetických neutronových zdrojů v Ústavu jaderné fyziky, Řež, a ve Svedbergově laboratoři, Uppsala, Švédsko. Bylo provedeno celkem 11 ozařování v energetickém rozpětí 17 až 94 MeV. Prahové reakce byly změřeny až do (n,10n), výsledky byly porovnány s daty z databází EXFOR, EAF a s hodnotami vypočtenými pomocí programu TALYS. Byla pozorována dobrá shoda. Účinné průřezy pro reakce nad 40 MeV a (n,4n) jsou unikátní a byly změřeny vůbec poprvé. Část naměřených dat již byla publikována a prezentována na mezinárodních konferencích.