Calculations of Cross-Sections and Astrophysical S-factors for the (α,n) Reactions of Some Structural Fusion Materials

Structural material selection in design of fusion reactors is very crucial. These structural materials should satisfy the hard conditions such as high thermo-mechanical stresses, high heat loads and severe radiation damage without compromising on safety considerations. The materials such as titanium, vanadium and chromium are used in the construction of fusion reactors. Therefore, it is important to examine these materials. Obtained results from the nuclear reactions using structural materials can be used for developing of these structural materials. For this reason, in this study cross sections of the ⁴⁶Ti(α,n) ⁴⁹Cr, ⁵⁰Cr(α,n) ⁵³Fe and ⁵¹V(α,n) ⁵⁴Mn reactions have been calculated at 2–20 MeV energy range. In these theoretical calculations, the TALYS 1.8 and NON-SMOKER codes were used. Also, the astrophysical S-factors which describe the possibility of reaction in low energies were calculated. Results of our calculations were checked to the experimental data obtained from EXFOR database.     

Calculations of Excitation Functions of Some Structural Fusion Materials for (<Emphasis Type="Italic">n</Emphasis>, <Emphasis Type="Italic">t</Emphasis>) Reactions up to 50 MeV Energy

Fusion serves an inexhaustible energy for humankind. Although there have been significant research and development studies on the inertial and magnetic fusion reactor technology, there is still a long way to go to penetrate commercial fusion reactors to the energy market. Tritium self-sufficiency must be maintained for a commercial power plant. For self-sustaining (D-T) fusion driver tritium breeding ratio should be greater than 1.05. So, the working out the systematics of (n, t) reaction cross sections is of great importance for the definition of the excitation function character for the given reaction taking place on various nuclei at different energies. In this study, (n, t) reactions for some structural fusion materials such as ²⁷Al, ⁵¹V, ⁵²Cr, ⁵⁵Mn, and ⁵⁶Fe have been investigated. The new calculations on the excitation functions of ²⁷Al(n, t)²⁵Mg, ⁵¹V(n, t)⁴⁹Ti, ⁵²Cr(n, t)⁵⁰V, ⁵⁵Mn(n, t)⁵³Cr and ⁵⁶Fe(n, t)⁵⁴Mn reactions have been carried out up to 50 MeV incident neutron energy. In these calculations, the pre-equilibrium and equilibrium effects have been investigated. The pre-equilibrium calculations involve the new evaluated the geometry dependent hybrid model, hybrid model and the cascade exciton model. Equilibrium effects are calculated according to the Weisskopf–Ewing model. Also in the present work, we have calculated (n, t) reaction cross-sections by using new evaluated semi-empirical formulas developed by Tel et al. at 14–15 MeV energy. The calculated results are discussed and compared with the experimental data taken from the literature.     

Investigation of the nuclear structure of the Be, Cr and Cu isotopes

The Root-Mean-Square (RMS) nuclear charge, neutron and proton radii, charge, neutron and proton densities, neutron skin thickness and total binding energy per particle were calculated using the Hartree–Fock method with Skyrme forces for the chromium (Cr), copper (Cu) and beryllium (Be) isotopes. The obtained results were compared with the experiment. Additional to these calculations the initial neutron and proton exciton numbers for ⁵²Cr isotope were also calculated. These exciton numbers can be used for pre-equilibrium proton induced (p, xn) reactions on ⁵²Cr isotope.     

Calculation of Excitation Function of Some Structural Fusion Material for (n, p) Reactions up to 25 MeV

Fusion serves an inexhaustible energy for humankind. Although there have been significant research and development studies on the inertial and magnetic fusion reactor technology, Furthermore, there are not radioactive nuclear waste problems in the fusion reactors. In this study, (n, p) reactions for some structural fusion materials such as ²⁷Al, ⁵¹V, ⁵²Cr, ⁵⁵Mn and ⁵⁶Fe have been investigated. The new calculations on the excitation functions of ²⁷ Al(n, p) ²⁷ Mg, ⁵¹ V(n, p) ⁵¹ Ti, ⁵² Cr(n, p) ⁵² V, ⁵⁵ Mn(n, p) ⁵⁵ Cr and ⁵⁶ Fe(n, p) ⁵⁶ Mn reactions have been carried out up to 30 MeV incident neutron energy. Statistical model calculations, based on the Hauser–Feshbach formalism, have been carried out using the TALYS-1.0 and were compared with available experimental data in the literature and with ENDF/B-VII, T = 300 K; JENDL-3.3, T = 300 K and JEFF-3.1, T = 300 K evaluated libraries.     

An Investigation for Ground State Features of Some Structural Fusion Materials

Environmental concerns associated with fossil fuels are creating increased interest in alternative non-fossil energy sources. Nuclear fusion can be one of the most attractive sources of energy from the viewpoint of safety and minimal environmental impact. When considered in all energy systems, the requirements for performance of structural materials in a fusion reactor first wall, blanket or diverter, are arguably more demanding or difficult than for other energy system. The development of fusion materials for the safety of fusion power systems and understanding nuclear properties is important. In this paper, ground state properties for some structural fusion materials as ²⁷Al, ⁵¹V, ⁵²Cr, ⁵⁵Mn, and ⁵⁶Fe are investigated using Skyrme–Hartree–Fock method. The obtained results have been discussed and compared with the available experimental data.     

Deuteron-Induced Cross Section Calculations of Some Structural Fusion Materials

The development of fusion materials for the safety of fusion power systems and understanding nuclear properties is important. The reaction cross-section data have a critical importance on fusion reactors and development for fusion reactor technology. In this study, the theoretical cross sections of some structural fusion materials such as Cr, V, Fe, Ni, Zr and Ta in deuteron-induced reactions have been investigated. The new calculations on the excitation functions of ⁵⁰Cr(d, α)⁴⁸V, ⁵¹V(d, 2n)⁵¹Cr, ⁵¹V(d, 4n)⁴⁹Cr, ⁵⁴Fe(d, α)⁵²Mn, ⁵⁴Fe(d, n)⁵⁵Co, ⁵⁸Ni(d, α)⁵⁶Co, ⁹⁶Zr(d, n)⁹⁷Nb, ⁹⁶Zr(d, 2n)⁹⁶Nb and ¹⁸¹Ta(d, 2n)¹⁸¹W reactions have been carried out up to 90 MeV incident deuteron energies. In these calculations, the pre-equilibrium and equilibrium effects have been investigated. The pre-equilibrium calculations involve the geometry dependent hybrid model and hybrid model. Equilibrium effects have been calculated according to the Weisskopf–Ewing model. The ALICE/ASH computer code has been used in all calculations. The calculated results have been compared with the experimental data existing in EXFOR database and found to be in good agreement.     

Activation cross-sections of deuteron induced nuclear reactions on manganese up to 40 MeV

In the frame of a systematic study on activation cross-sections of deuteron induced reactions experimental excitation functions on ⁵⁵Mn were measured with the activation method using the stacked foil irradiation technique up to 40 MeV. By using high resolution γ-ray spectrometry, cross-section data for the production of ^56,54,52Mn and ⁵¹Cr were determined. Comparison with the earlier published data and with the results predicted by the ALICE-IPPE and EMPIRE-II theoretical codes - improved for more reliable calculations for d-induced reactions - and with data in the TENDL 2010 libraries are also included. Thick target yields were calculated from a fit to our experimental excitation curves and implications for practical applications in industrial (Thin Layer Activation) accelerator technology are discussed.     

Simultaneous Determination of Radionuclides in Seawater by Hydroxide Precipitation

A method was established for determining simultaneously ⁵¹Cr, ⁵⁴Mn, ⁵⁹Fe, ⁵⁸Co, ⁶⁰Co, ⁹⁵Zn, ⁹⁵Zr, ⁹⁵Nb and ¹⁴⁰La present in seawater in concentrations corresponding to 5mrem/yr for whole-body dose, the level set as guideline by the Japan AEC for light-water-cooled power reactor.

Prior to concentration of the sample by precipitation of hydroxides at pH 10.5, Chromate ion was reduced to trivalent form by treatment with sulfurous acid and 1% of hydrochloric acid. After the concentration, the sample was found to retain 85% of Zr and Nb, and 95% of the other elements of interest in the original sample. The determination of ⁵⁹Fe, ⁹⁵Zn and ⁹⁵Zr called for removal of Mg, which was obtained by re-precipitation of the nuclides at pH 7.5.

The method thus established by the basic study was applied to trial treatment of 400l of natural seawater, which yielded percentage of recovery practically equal to those obtained in the basic study for Cr, Mn and Co. The proposed method proved to permit determination of concentrations below those specified previously by the authors as needed for effective assessment of the environment to accord with the AEC guideline. The time required for the chemical procedures and the γ-spectrometry to determine the nine radionuclides in 400 l of natural seawater is about 34 h. The proposed method is practical in terms also of the time required for the determination     

Calculations of Proton Emission Cross Sections in Deuteron Induced Reactions of Some Fusion Structural Materials

The growing demands for energy consumption have led to the increase of the research and development activities on new energy sources. Fusion energy has the highest potential to become a very safe, clean and abundant energy source for the future. To get energy from fusion are needed for development of fusion reactor technology. Particularly, the design and development of international facilities as International Thermonuclear Experimental Reactor and International Fusion Material Irradiation Facility requires for the cross-section data of deuteron induced reactions. Moreover, the selection of fusion structural materials are an indispensable component for this technology. Therefore, the cross-section data of deuteron induced reactions on fusion structural materials are of great importance for development of fusion reactor technology. In this study, reaction model calculations of the cross sections of deuteron induced reactions on structural fusion materials such as ²⁷Al, ⁵⁹Co, ⁵⁵Mn, ⁵⁰Cr, ⁵⁴Cr, ⁶⁴Ni, ¹⁰⁹Ag, ¹⁸⁴W and ¹⁸⁶W have been carried out for incident energies up to 50 MeV. In these calculations, the pre-equilibrium and equilibrium effects for (d,p) stripping reactions have been investigated. The pre-equilibrium calculations involve the new evaluated the geometry dependent hybrid model and hybrid model. Equilibrium effects are calculated according to the Weisskopf-Ewing model. In the calculations the program code ALICE/ASH was used. The calculated results are discussed and compared with the experimental data taken from the literature.     

Effect of He-pre-injection on dislocation loop formation and irradiation-induced segregation of Fe–12%Cr–15%Mn austenitic steel

The effect of He-injection on irradiation-induced segregation of aging treated Fe–12%Cr–15%Mn austenitic steels, which are candidate materials as the reduced radio-activation of structure material for nuclear and/or fusion reactors was investigated by using the 1250 kV high voltage electron microscope (HVEM) connected with an ion accelerator. The Fe–Mn–Cr steel has been irradiated at 573 K by three irradiation modes of single electron-beam irradiation, electron-beam irradiation after He-injection and electron/He⁺-ion dual-beam irradiation in a HVEM. Irradiation-induced segregation analyses were carried out by an energy dispersive X-ray analyzer (EDX) in a 200 kV FE-TEM with beam diameter of about 0.5 nm. Dislocation loops with strain contrast were formed during irradiation and the loop numbers density increased rapidly with irradiation dose for He-pre-injected specimens. Voids were not observed after irradiations with three irradiation modes up to 5.4 dpa at 573 K. Irradiation-induced segregations of Cr and Mn near grain boundary were observed in each irradiation condition, but the amounts of Mn segregation decreased in the cases of electron/He⁺-ion dual-beam irradiation compared with single electron-beam and electron-beam irradiation after He-injection conditions.     

Nuclear data sheets for A = 55

The 1970 version of Nuclear Data Sheets for A = 55 has been revised on the basis of experimental data received prior to March 1, 1976. Results from approximately 220 papers and communications have been included in the present evaluation.Data on five A = 55 nuclei are presented. The decay schemes for ⁵⁵Cr, ⁵⁵Fe, and ⁵⁵Co are well established. Many excited levels are known in ⁵⁵Cr, ⁵⁵Mn, ⁵⁵Fe, and ⁵⁵Co from a variety of decay and reaction experiments. Many firm or tentative spin assignments are made, and many half-lives for excited levels in ⁵⁵Mn, ⁵⁵Fe, and ⁵⁵Co have been measured. An uncertainty in the level scheme for ⁵⁵Mn occurs near 1290 keV, where the number of distinct levels and their spins cannot be unambiguously determined. The nucleus ⁵⁵Ni has been observed for the first time in the (³He, ⁶He) reaction, but the decay of ⁵⁵Ni has not yet been observed.     

Nuclear Data Sheets for A = 65

The evaluators present in this publication spectroscopic data and level schemes from radioactive decay and nuclear reactions studies for all isobars with mass number A=65. Not much is known experimentally about ⁶⁵V and ⁶⁵Cr, although they are expected to decay by β-emission. Spin/parity assignments for ⁶⁵Mn, ⁶⁵Fe, ⁶⁵As, and ⁶⁵Se are not firmly established.     

Highly sensitive AMS measurements of 53Mn

Our AMS system, with the gas-filled detector system GAMS, has been optimized for measurements with ⁵³Mn. A high sensitivity has been achieved. A newly installed cesium sputter ion source yields an improved emittance, and thus a higher mass resolution. By the extraction of the manganese molecule MnF^? instead of MnO^? we can suppress the isobaric chromium background in the ion source by more than a factor of three. The GAMS system achieves an isobaric suppression factor of about 3 × 10⁸. Measurements on blank samples yielded upper limits for the ⁵³Mn/⁵⁵Mn ratios of 7 × 10^?15.     

Nuclear Data Sheets for A = 62

Experimental nuclear spectroscopic data for known nuclides of mass number 62 (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge) have been evaluated and presented together with adopted properties of levels and γ rays. New high-spin data are available for ⁶²Ga, and ⁶²Zn. Results of in-beam γ-ray studies for ⁶²Cu producing high-spin states are in conflict in terms of gamma-ray placements and branching ratios. In the opinion of the evaluators, a detailed study of high-spin structures in ⁶²Cu is needed to obtain a consistent and confident level scheme. Precise studies of superallowed β decay of ⁶²Ga to ⁶²Zn by several groups have extended the decay scheme. No significant new data, since the 2000 NDS for A = 62 (2000Hu18), have been reported for ⁶²Co, ⁶²Ni and ⁶²Cu. No data are yet available for excited states in ⁶²Ti and ⁶²V, and those for ⁶²Cr and 62Ge are scarce. The level lifetime data are available in very few cases. The radioactive decay schemes of ⁶²Ti and ⁶²Ge are unknown, and those for ⁶²V, ⁶²Cr and 92-ms ⁶²Mn are scantily known. The data presented here supersede those in the earlier NDS publications.     

Nuclear Data Sheets for A = 44

The experimental data are evaluated for known nuclides of mass number A=44 (Si,P,S,Cl,Ar,K,Ca,Sc,Ti,V, Cr,Mn). Detailed evaluated level properties and related information are presented, including adopted values of level and γ-ray energies, decay data (energies, intensities and placement of radiations), and other spectroscopic data. This work supersedes earlier full evaluations of A=44 published by 1999Ca45 and 1990En08 (also 1998En04 update).No excited states are known in ⁴⁴Si, ⁴⁴P, ⁴⁴Cr, ⁴⁴Mn. Only one excited state is known in 44V and its Isobaric Analog State (IAS) has been observed but with the level energy not known. Information for ⁴⁴S, ⁴⁴Cl and ⁴⁴Ar is limited and their radioactive decay schemes seem incomplete in view of large Q values and known excitations much below than allowed by Q values. The ⁴⁴Ca, ⁴⁴Sc and ⁴⁴Ti nuclides remain as the most extensively studied from many different reactions and decays.     

The 63Cu(n,2n)62Cu and 65Cu(n,2n)64Cu cross sections at 14.8 MeV

Measurements have been made of the ⁶³Cu(n,2n)⁶²Cu and ⁶⁵Cu(n,2n)⁶⁴Cu cross sections. Separated isotope targets were irradiated with 14.8 MeV neutrons and the resulting ⁶²Cu and ⁶⁴Cu activities were measured using both 4πβ-γ coincidence counting and by counting in coincidence the annihilation radiation produced following the β⁺-decay of ⁶²Cu and ⁶⁴Cu. The variation in the neutron flux and the neutron energy were measured during each single irradiation. Good agreement was obtained for the cross-section values using the two methods. However, the standard deviation of the mean of the ⁶⁵Cu(n,2n)⁶⁴Cu cross-section measurements was significantly greater when the 4πβ-γ coincidence method was used. The measurements were made relative to the ⁵⁶Fe(n,p)⁵⁶Mn cross section. Values of 549 ± 11 and 968 ± 20 mbarn were obtained using a value of 108.5 mbarn for the Fe cross section at 14.8 MeV.     

Nuclear Data Sheets for A = 56

The 1999 publication of Nuclear Data Sheets for A=56 (1999Hu04) has been updated using experimental nuclear structure data and decay data available before November 2009. The information for ⁵⁶K, ⁵⁶Ca, ⁵⁶Sc, ⁵⁶Ti, ⁵⁶V, ⁵⁶Cr, ⁵⁶Mn, ⁵⁶Fe, ⁵⁶Co, ⁵⁶Ni, ⁵⁶Cu, and ⁵⁶Zn from various reaction and decay experiments together with their adopted levels and γ transition properties is summarized and presented.     

Isobaric identification techniques of AMS at CIAE

Some long-lived nuclides, such as ³⁶Cl, ⁴¹Ca, ⁵³Mn, ⁷⁹Se, etc., are very interested in life science, environment science, geo- and cosmo-sciences, nuclear wastes management, and other fields. Taking the advantages in high sensitivity and the strong ability to reduce the interferences from molecular ions and isobars, AMS has been one of the most promising methods for the measurement of these nuclides. However, the sensitivity of AMS is often unsatisfactory due to the interferences of stable isobars especially for medium and heavy radioisotopes. Gas-filled time of flight (GF-TOF), Gas-filled Magnet with a time of flight (GFM-TOF), Bragg Curve detector and energy loss (ΔE) combined with a Q3D magnetic spectrometer (ΔE-Q3D) are among the techniques used or being developed in AMS lab of China Institute of Atomic Energy, in an attempt to further reduce the interferences from isobars. These techniques will be tested in our AMS measurement of ⁵³Mn, ⁷⁹Se, ⁹³Zr, ⁹⁹Tc, etc., for identifying isobaric interferences.     

Photo-Neutron Production in Heliotron-E

Photo-neutron emission in H₂ and He discharges was observed in the initial ohmic heating experiments of the Heliotron-E. Typical total neutron yield was 10⁹ neutrons per pulse under high level of runaway electrons (≧10 MeV). Neutron flux was localized near the limiters. Energy spectrum of neutrons was continuous up to about 2 MeV. The radioactive nuclides in the limiters and the vacuum chamber irradiated by runaway electrons showed that ⁵⁸Ni(γ, n) ⁵⁷Ni and ⁵³Cr(γ, n)⁵¹Cr reactions had occurred, proving that the photo-disintegration process was the source of neutron flux.     

Measurement and calculations of long-lived radionuclide activity forming in the fast neutron field in some ITER construction steels

Measurement and calculations of long-lived gamma-emitting radionuclide activity forming in the fission reactor fast neutron field were done, for some ITER construction steels. The activation was conducted in fast neutron irradiation channel of the MARIA research fission reactor (Poland). The dimensions of steel samples were 10 mm × 10 mm × 1 mm and mass was approximately 0.8 g. The neutron flux density was measured by means of activation foil method and unfolding technique; fraction of neutrons above 1 keV was 95%. The activation lasted 242 h and cooling took 100 days; the mean neutron flux density was 2.9E12 n/(cm² s) (neutrons above 500 keV are 53% of total) whereas total fluency 2.53E18 cm⁻². The activity measurements were done by means of gamma-ray spectrometry. Activity calculations were done by means of FISPACT-II code using the activation libraries EAF-2010 and TENDL-2011 and experimentally determined neutron flux. Measured activity of long-lived gamma emitting radionuclides was, in average, about 6.3 MBq/g 100 days after activation; the dominant radionuclides were ⁵⁸Co and ⁵⁴Mn (about 81% and 14% of total activity respectively). The C/E ratio differs for particular radionuclides and is in the range 0.86–0.92 for ⁵¹Cr, 0.93–1.21 for ⁵⁴Mn, 0.77–0.98 for ⁵⁷Co, 0.91–1.21 for ⁵⁸Co, 1.17–1.27 for ⁵⁹Fe, and 1.75–2.44 for ⁶⁰Co.