Triton Energy Research Articles

Calculation of tritium release from driver fuels into primary coolant of research reactors

Increasing of tritium concentration in the primary coolant of the research and test reactors during operationhad been reported. To check the source for tritium release into the primary coolant during operation of theJMTR and the JRR-3M, the tritium release from the driver fuels was calculated by MCNP6 and PHITS. Itis clear that the calculated values of tritium release from fuels are as about 107 and 106 Bq for the JMTR andJRR-3M, respectively, and that calculated values are about 4 order of magnitude smaller than that of themeasured values. The JMTR is a tank type, and the JRR-3M is a pool type research reactor. The primarycoolants are light water, in which the coolant temperature is lower than 50ºC. These results show that thetritium release from fuels is negligible for both the reactors. In the calculations of tritium release rates intothe water by PHITS, a gaussian triton energy by ternary fissions of 235U.

Investigation of discrete states and quasidiscrete structures observed in Sm150 and Sm152 using the (p,tγ) reaction

New levels and $\ensuremath{\gamma}$-ray transitions were identified in $^{150,152}\mathrm{Sm}$ utilizing the $(p,t)$ reaction and particle-$\ensuremath{\gamma}$ coincidence data. A large, peak-like structure observed between 2.3--3.0 MeV in excitation energy in the triton energy spectra was also investigated. The orbital angular-momentum transfer was probed by comparing the experimental angular distributions of the outgoing tritons to calculated distorted wave Born approximation curves. The angular distributions of the outgoing tritons populating the peak-like structure are remarkably similar in the two reactions and are significantly different from the angular distributions associated with the nearby continuum region. Relative partial cross sections for the observed levels, angle averaged between 34 and 58 degrees, were measured. In $^{150}\mathrm{Sm}$, 39(4)% of the strength of the peak-like structure could be accounted for by the observed discrete states. This compares with a value of 93(15)% for $^{152}\mathrm{Sm}$.

Angle-Dependent Double-Differential Neutron Emission Cross Sections of 3H(t,n) between 5.98 and 19.14 MeV and Evidence of 4H as Intermediate Reaction Product

Neutrons for fusion applications stem not only from monoenergetic sources but also from “white” neutron sources. In this regard, the reaction 3H(t,n) is of particular interest. Continuous neutron spectra of the 3H(t,n) reactions were measured at 5.98-, 7.47-, 10.45-, 16.41-, and 19.14-MeV triton energy at typically seven angles between 0 and 145 deg. The spectra at the three lowest energies contain only neutrons from 3H(t,n)5He and 3H(t,2n)4He reactions and therefore can more easily be interpreted than the spectra at 16.41 and 19.14 MeV, which are too complex to allow a straightforward decomposition except for estimation of the neutron emission cross section following the reaction 3H(t,d)4H. Angle-dependent double-differential and neutron energy—integrated cross sections are given at the five energies. In most cases the peak of the two-body ground state transition could be deconvolved reliably resulting in cross sections of the reaction 3H(t,n)5He. Although the basic scale uncertainty is >5%, severe background, in particular, at the higher triton energies, increases the total uncertainty of integrated cross sections up to 9%. Naturally, the uncertainty of each energy bin of the double-differential cross sections, which depend on bin width, is considerably higher. As no previous data are reported at or near these energies, no direct comparison with other data was feasible. Evidence is provided of the formation of the short-lived neutron-rich nuclei 5He and at higher energies of 4H.

Double-Differential Angle-Dependent Three-Body Neutron Production Cross Sections of the Reaction 2H(t,n)X+Y at Triton Energies between 5.97 and 16.41 MeV

Monoenergetic neutron production by nuclear reactions among light elements and the production of white neutrons by such reactions are of particular interest for fusion applications. Data reduction of continuous neutron spectra is generally hampered by a lack of adequate background spectra. To find the best background spectrum for the measurement of 3H(t,n) double-differential cross sections, much effort was applied to determining a reliable background spectrum stemming from a tritium gas cell. Since the measurement of the 2H(t,n)4He reaction that was used for the efficiency determination used the same gas cell, the same background spectra could be used, and continuous neutron spectra stemming from the three-body (n+X+Y) reactions of 2H(t,n)X+Y could be extracted reliably. Thus, double-differential three-body neutron production cross sections were determined at 5.97, 7.47, 10.45, and 16.41 MeV, at angles between 0 and 90 deg with a scale uncertainty of <4%. Corresponding data with projectile and target particles exchanged are available in the same center-of-mass energy range with uncertainties of ~25%.

Measuring the Neutron Signature of the t→d+n Triton Breakup Reaction and the Angle-Dependent Differential Cross Section of 6Li(n,t)4He at 2.32 MeV

The continuous neutron spectrum from the t→d+n breakup reaction can best be extracted in the 3H(p,n)3He and 4He(t,n)6Li reactions because of minimum neutron background in both cases. Only for the latter reaction are neutron background spectra also available. These data were measured at 11.88-MeV triton energy at eight angles between 0 and 120 deg. As a test for the validity of the procedure, angle-dependent differential cross sections of 4He(t,n)6Li were extracted and converted to 6Li(n,t)4He at En = 2.32 MeV by detailed balance calculation thus contributing to the R-matrix analysis of the 7Li system. The double-differential and neutron energy integrated cross sections at that energy are given as well as those for the triton breakup of the time-reversed reaction.

Determining the 6Li doped side of a glass scintillator for ultra cold neutrons

Ultracold neutron (UCN) detectors using two visually very similar, to the microscopic level, pieces of optically contacted cerium doped lithium glasses have been proposed for high rate UCN experiments. The chief difference between the two glass scintillators is that one side is 6Li depleted and the other side 6Li doped. This note outlines a method to determine which side of the glass stack is doped with 6Li using AmBe and 252Cf neutron sources, and a Si surface barrier detector. The method sees an excess of events around the α and triton energies of neutron capture on 6Li when the enriched side is facing the Si surface barrier detector.

ON THE MODELLING OF SWELL WAVE PENETRATION INTO TIDAL INLET SYSTEMS

For the calculations of the Hydraulic Boundary Conditions in the framework of the Dutch Legal Flood Safety Assessment (WTI), wave statistics obtained at deeper water buoys need to be transformed to the toe of the dike using the wave action model SWAN. This transformation is particularly challenging in complex tidal inlet systems such as the Wadden Sea and the Western Scheldt in the Netherlands. Although various model improvements have been made in SWAN, particularly in the propagation and bottom friction dissipation, one of the unresolved issues is that the penetration of North Sea swell waves into the tidal inlets is still underestimated by SWAN. The goal of this study is to verify the hypothesis that nonlinear interactions, in particular the sub-harmonic triad interactions, play a major role in the transmission of energy from flats into the channel, and that this process can explain SWAN’s under-prediction of wave energy penetration. Since SWAN or any other wave-action equation type models lacks the relevant physics to study this problem, the Boussinesq-type TRITON model is used as well to verify the hypothesis. The conceptual idea, raised by Toledo (2013), is that sub-harmonic wave interactions between second harmonic and basic components generate a wave component of the same frequency as the primary component but at a wider angle of approach. As a consequence, the energy density spectra become directionally broader. From a series of idealized cases with monochromatic and bi-chromatic waves propagating up and down a slope we conclude that the TRITON model results confirm the conceptual idea of 2D nonlinear interactions. Both sub-harmonic wave interactions (to lower frequencies) and super-harmonic wave interactions (to higher frequencies) prove to be important. These insights can be applied to the situation with waves propagating on a tidal flat towards a channel. In case the basic components approach the channel under a sharp angle, such that they will not be able to enter the channel due to refraction, the sub-harmonic components could approach the channel under a less sharp angle and enter the channel. In our study a clear difference between the TRITON and SWAN energy density spectra in and across the channel is observed, as the 2D nonlinear interactions cannot be modeled with the co-linear 1D approach in SWAN. The hypothesis that nonlinear interactions play a major role in the transmission of energy from flats into the channel is confirmed, at least for the cases considered in this study. Additional investigations are still required in order to quantify and generalize the effect of nonlinear interactions on this transmission of energy. In addition, it is recommended to extend the presently implemented three-wave interaction formulation in SWAN to account for directional super- and sub-harmonic interactions.

Improved Simulation of the Pre-equilibrium Triton Emission in Nuclear Reactions Induced by Nucleons

A new approach is proposed for the calculation of non-equilibrium triton energy distributions in nuclear reactions induced by nucleons of intermediate energies. It combines models describing the nucleon pick-up, the coalescence and the triton knock-out processes. Emission and absorption rates for excited particles are represented by the pre-equilibrium hybrid model. The model of Sato, Iwamoto, Harada is used to describe the nucleon pick-up and the coalescence of nucleons from exciton configurations starting from (2p,1h) states. The contribution of the direct nucleon pick-up is described phenomenologically. Multiple pre-equilibrium emission of tritons is accounted for. The calculated triton energy distributions are compared with available experimental data.

Searching for resonances in the unbound 6Be nucleus by using a radioactive 7Be beam

Knowledge of the 3He(3He,2p)4He reaction is important for understanding stellar burning and solar neutrino production. Previous measurements have found a surprisingly large rise in the cross section at low energies that could be due to a low-energy resonance in the 3He + 3He (6Be) system or electron screening. In the 6Be nucleus, however, no excited states have been observed above the first 2+ state at Ex = 1.67 MeV up to 23 MeV, even though several are expected. The 2H(7Be,3H)6Be reaction has been studied for the first time to search for resonances in the 6Be nucleus that may affect our understanding of the 3He(3He,2p)4He reaction. A 100-MeV radioactive 7Be beam from the Holifield Radioactive Ion Beam Facility (HRIBF) was used to bombard CD2 targets, and tritons were detected by using the silicon detector array (SIDAR). A combination of reaction mechanisms appears to be necessary to explain the observed triton energy spectrum.

TheSi28(p,t)Si26*(p) reaction and implications for the astrophysicalAl25(p,γ)Si26reaction rate

Several resonances in $^{25}\mathrm{Al}$($p,\ensuremath{\gamma}$)$^{26}\mathrm{Si}$ have been studied via the $^{28}\mathrm{Si}$($p,t$)$^{26}\mathrm{Si}$ reaction. Triton energies and angular distributions were measured using a segmented annular detector array. An additional silicon detector array was used to simultaneously detect the coincident protons emitted from the decay of states in $^{26}\mathrm{Si}$ above the proton threshold in order to determine branching ratios. A resonance at $5927\ifmmode\pm\else\textpm\fi{}4$ keV has been experimentally confirmed as the first $\ensuremath{\ell}=0$ state above the proton threshold, with a proton branching ratio consistent with one.

Neutral particle measurements of fusion tritons in JET

A neutral particle analyzer [A.D. Izvozchikov et al., JET Report No. JET-R(91)-12, 1991] operating in the MeV energy range was used to measure the flux of neutralized d-d fusion tritons emitted from the hot-ion H-mode deuterium plasma heated by deuterium neutral beams. It was found that tritons in the energy range of 0.3–1.1 MeV were largely neutralized by the beam atoms and the beam halo atoms. This enabled us to find the localized energy distribution function of the fusion tritons in the central plasma region. Simulation of the triton energy distribution function shows that MeV ions in the JET hot-ion H-mode plasma behave classically.

On the 24Mg(t, p) Reaction in the Incident Energy Range of 1.65–3.4 MeV

Previously, cross sections and angular distributions of the 24Mg(t, p) reaction were measured in the incident triton energy range of 1.65–3.4 MeV. Presently, the analysis of the reaction is made with a combined model of the resonance and direct reactions. Almost good agreement was obtained between the experiment and the analysis. Some excited states of the compound nucleus 27Al in Ex = 19:68–21:23 MeV were determined by the resonance analysis.

On the 24Mg(t, p) Reaction in the Incident Energy Range of 1.65–3.4 MeV

Previously, cross sections and angular distributions of the 24Mg(t, p) reaction were measured in the incident triton energy range of 1.65–3.4 MeV. Presently, the analysis of the reaction is made with a combined model of the resonance and direct reactions. Almost good agreement was obtained between the experiment and the analysis. Some excited states of the compound nucleus 27Al in Ex = 19:68–21:23 MeV were determined by the resonance analysis.

Exploration and development of Ceiba Field, Rio Muni Basin, Southern Equatorial Guinea

Ceiba Field, offshore Equatorial Guinea approximately 75 km southwest of the port of Bata and 275 km south of the city of Malabo, was discovered with the drilling of Ceiba-1 in September 1999. The first appraisal well, Ceiba-2, was drilled in November 1999 approximately 1.6 km southwest of Ceiba-1. Both wells were based on interpretation of 2D seismic data acquired between 1984 and 1999. Open-hole logs, cores, pressure data, and a drill stem test of Ceiba-1 (maximum flow rate of 12 400 b/d) indicated that both wells contained Cretaceous sands of very high quality, capable of high rates of oil production. Despite being between two prolific hydrocarbon provinces—Niger delta to the north and the Gabon coastal basin to the south (Figure 1)—Rio Muni Basin was essentially overlooked by the industry until the late 1990s. Six wells were drilled between 1968 and 1991 in the shelfal and onshore areas of the basin. These focused on Albian and Aptian aged objectives and, although they proved the presence of a viable source rock, the early wells did not result in the discovery of any oil accumulations. Figure 1. Ceiba Field is offshore Equatorial Guinea approximately 75 km southwest of the port of Bata and 275 km south of the city of Malabo. In 1997, following a review of the West African margin, Triton Energy identified a number of aspects of Rio Muni Basin that suggested an unexplored deepwater play. These included an immature oil-prone source in shelfal wells, which had the potential to be more deeply buried in the outboard part of the basin, and evidence for base of slope structuring on the margins of the shelf in the 2D data. The presence of shelfal canyons suggested that bypassed clastics could potentially be deposited in deepwater. The presence, in the Sergipe-Alagoas Basin of Brazil, of …

Investigation of the Threshold Anomaly in Excitation Function of 11B(t, p)13B Reaction

To accumulate experimental data for theoretical investigation of threshold phenomena in nuclear reactions the excitation function of the 11B(t, p)13B reaction has been measured in the triton energy range Et=2.6-4.2 MeV which includes the threshold of the 11B(t, n)13C*(15.108 MeV, Jπ=3/2’, T=3/2) reaction at Et=3.42 MeV. With that purpose the boron layer (375 µgcm-2 thick and enriched to 92% in 11B) on tantalum backing (0.2 mm thick) were bombarded with tritons of the electrostatic tandem accelerator. Using pulsed mode of target irradiation delayed 3.681 MeV ϒ-rays after γ-decay of 13B were observed with a Ge-detector. The expected strong anomaly was seen in the range Et=3.6-4.0 MeV. It is probably threshold anomaly which owes its origin to the threshold reaction and the observed isobaric- analog state of 14C with T=2.

Time-Dependent Coupled-Channel Calculations of Muon-Transfer Cross Sections in Muonic Deuterium and Triton Collisions

A time-dependent coupled channel (TDCC) method has been developed to study rearrangement reactions in few-body Coulomb systems. We apply the TDCC method to muon transfer in muonic deuterium and triton collisions. The muon-transfer cross section (S-wave) is calculated for triton energies of 100 eV–3 keV. The present result is in good agreement with the previous calculation with the coupled rearrangement channel method [Hyp. Interact. 82 (1993), 45]. We also illustrate time evolution of wave functions to understand qualitatively the muon-transfer reaction.

Confined trapped alpha behaviour in TFTR deuterium-tritium plasmas

Confined trapped alpha energy spectra and differentialradial density profiles in TFTR D-T plasmas were obtained with thepellet charge exchange (PCX) diagnostic, which measures high energy(Eα = 0.5-3.5 MeV) trapped alphas (v||/v = -0.048) at a single time slice (Δt ≈ 1 ms) with a spatialresolution of Δr ≈ 5 cm. Tritons produced in D-Dplasmas and RF driven ion tails (H, 3He or T) were also observedand energetic tritium ion tail measurements are discussed. PCX alphaand triton energy spectra extending up to their birth energies weremeasured in the core of MHD quiescent discharges where the expectedclassical slowing down and pitch angle scattering effects are notcomplicated by stochastic ripple diffusion and sawtooth activity.Both the shape of the measured alpha and triton energy distributionsand their density ratios are in good agreement with TRANSPpredictions, indicating that the PCX measurements are consistent withclassical thermalization of the fusion generated alphas and tritons.From calculations, these results set an upper limit on possibleanomalous radial diffusion for trapped alphas of Dα ⩽ 0.01 m2·s-1. Outside the core, where the trappedalphas are influenced by stochastic ripple diffusion effects, the PCXmeasurements are consistent with the functional dependence of theGoldston-White-Boozer stochastic ripple threshold on the alphaenergy and the q profile. In the presence of strong sawtoothactivity, the PCX diagnostic observes significant redistribution ofthe alpha signal radial profile wherein alphas are depleted in thecore and redistributed to well outside the q = 1 radius, butapparently not beyond the energy dependent stochastic ripple lossboundary. The helical electric field produced during the sawtoothcrash plays an essential role in modelling the sawtoothredistribution data. In sawtooth free discharge scenarios withreversed shear operation, the PCX diagnostic also observes radialprofiles of the alpha signal that are significantly broader thanthose for supershots. ORBIT modelling of reversed shear andmonotonic shear discharges is in agreement with the q dependentalpha profiles observed. Redistribution of trapped alpha particles inthe presence of core localized toroidal Alfvén eigenmode (TAE)activity was observed and modelling of the PCX measurements based ona synergism involving the α-TAE resonance and the effect ofstochastic ripple diffusion is in progress.

Recoil tritium in 304-stainless steel: the initial distribution revisited

A new experimental determination of the initial (as-deposited) concentration profile of recoil tritons (tritium) in a thick 304-S.S. target is compared with the linear recoil profile predicted by Di Cola/Matzke (DM) theory. Satisfactory agreement is observed. In the experiment, 2.72-MeV tritons produced by the 6Li(n, α) 3H reaction in a thick Li 2CO 3 powder inject a thick 304-S.S. slab with tritium. A subsequent acid etch of the slab followed by tritium and stainless steel radioassays yield the concentration profile. Monte Carlo simulations with the SRIM code show that a non-linear profile is expected, with an increasing departure from linearity occurring as the initial triton energy decreases below 2.72 MeV. DM theory is extended to cover in a slab configuration (a) recoil concentration in both source and target with arbitrary thicknesses, and (b) probability density functions describing recoil pathlength and energy distributions in a thick source and target.

Single-nucleon transfer to unbound states in the4He(α,t)5Lireaction at incident energies of 120, 160, and 200 MeV

The ${}^{4}\mathrm{He}(\ensuremath{\alpha}{,t)}^{5}\mathrm{Li}(\mathrm{g}.\mathrm{s}.)$ reaction was investigated at incident energies of 120, 160, and 200 MeV in order to resolve discrepancies found between previous measurements and theoretical predictions for the analogous reaction ${}^{4}{\mathrm{H}\mathrm{e}(\mathrm{\ensuremath{\alpha}},}^{3}{\mathrm{H}\mathrm{e})}^{5}\mathrm{He}(\mathrm{g}.\mathrm{s}.)$ at these energies. The line shapes of the ${}^{5}\mathrm{Li}$ ground-state resonance in the measured triton energy spectra are well reproduced by distorted-wave Born approximation (DWBA) calculations. Cluster-core optical potentials, which yield better overall agreement both for $\ensuremath{\alpha}\ensuremath{-}\ensuremath{\alpha}$ elastic scattering and for the single-nucleon transfer reactions, are presented. It is shown that the previously observed discrepancies in magnitude between measured and calculated cross sections by a factor of $\ensuremath{\sim}2$ can be improved by employing spectroscopic factors obtained from a realistic shell model for the transitions to the final mass-3 and mass-5 systems.

The40Ca(t,p)42Careaction at triton energies near 10 MeV per nucleon

Two nucleon transfer reactions have been used to probe for correlations in nuclei but there have been doubts about the assumptions made and hence about the success of the analyses. An experimental study of the ${}^{40}\mathrm{Ca}{(t,p)}^{42}\mathrm{Ca}$ reaction at incident triton energies of 10\char21{}15 MeV/nucleon was made to determine if the one-step, two-nucleon transfer mechanism was dominant at these energies. Measurements were made with 28, 33, and 37.3 MeV incident energy and particular care was taken to measure absolute differential cross sections for transitions to several residual states in ${}^{42}\mathrm{Ca}.$ The analysis of all the data used the results of full finite-range calculations and care was taken to calculate all the one-step and two-step reaction channels in a consistent manner starting from a shell-model description of the relevant Ca isotopes with a single, large basis set of single-particle wave functions. Although a complete prediction of the data was not achieved, it is concluded that incident triton energies about 10 MeV/nucleon are still not enough for one-step, two-nucleon transfer to dominate the $(t,p)$ reaction mechanism. Even with a full analysis, it was not possible to reliably extract the reaction amplitudes by fitting the data because of the effects of the discrete potential ambiguity when describing elastic scattering. Hence it is not possible to extract accurate data about two-nucleon correlations in nuclei from $(t,p)$ reactions at these energies. Additionally, some measurements on the ${}^{8}\mathrm{Ca}{(t,p)}^{50}\mathrm{Ca}$ reaction with 37.3 MeV incident energy are presented. Using a similar analysis, calculations predicted the magnitude of the differential cross-section data and the structure of the angular distributions. The ${J}^{\ensuremath{\pi}}$ of the second excited state of ${}^{49}\mathrm{Ca}$ was shown to be ${7/2}^{\ensuremath{-}}.$