Summation Calculations Research Articles

Reactor antineutrinos and novel application to real-time remote monitoring of nuclear reactors

ABSTRACT We have constructed a computational scheme to obtain energy spectra of reactor antineutrinos, including the inverse β -decay process through which they were to be detected. The antineutrino spectra from all the fission products were calculated based on the gross theory of β -decay. This data was combined with an inventory of fission products obtained by burnup calculations, and then multiplicity and reactor antineutrinos spectra were obtained by a summation calculation. We compared aggregate antineutrino spectra emitted from four major actinoids 235 U , 238 U , 239 Pu , and 241 Pu calculated in this work with experimental values. We found that those obtained by using Fission-Product Yield (FPY) data of JENDL-5 could reproduce the measured data better than or almost equivalently with those obtained with FPY data of other recent nuclear data libraries. Then, we proposed a new method of nuclear safeguards by using reactor antineutrinos; namely, we found that changes in the number and energy spectra of reactor antineutrinos were strongly correlated with burnup and fissile composition of light-water reactors.

Total Absorption Spectroscopy of Fission Fragments Relevant for Reactor Physics and Nuclear Structure and Astrophysics

The accurate determination of reactor antineutrino spectra remains a very hot research topic, where new questions have emerged in recent years. Indeed, after the “reactor anomaly” – a deficit of measured antineutrinos at short baseline reactor experiments with respect to spectral predictions – the three international reactor neutrino experiments Double Chooz, Daya Bay and Reno have evidenced spectral distortions in their measurements with respect to the same spectral predictions. This puzzle is called the “shape anomaly”. Recently summation calculations of reactor antineutrino spectra based on the use of nuclear data have obtained the best agreement to date with the reactor neutrino flux measurements at the level of 2% thanks to a decade of Total Absorption Gamma-ray Spectroscopy (TAGS) measurements at the radioactive beam facility of the University of Jyväskylä in two experimental campaigns. A selection of the results obtained so far is presented.

Decision Support System Penentuan Jurusan Siswa Baru SMA Menggunakan Metode Simple Additive Weighting

There is a change in the curriculum as well as the increasing number of students from year to year, many criteria are used in determining student majors according to the interests of students talent and desires. With these constraints it will affect the calculations process, so that the results obtained later do not rule out the possibility of non-objective selection. Therefore, the process of majoring in sma negeri 1ungaran which is still done manually need to switch digitization, namely by making a Decision Support System which will later be more effective, efficient and determined according to exixting criteria. This research was designed and developed using the PHP and MYSQL programming languages as the database and using the Simple Additive Weighting (SAW) method to perform weighted summation calculations containing ceveral criteria. From the results of testing using blackbox shows that this program can work according to its function, namely being able to input data and perform calculations for determining student majors. As well as accuracy testing which produces a fairly good level of accuracy of 80% from 100%. From the results of this study, it can be concluded that this system can determine students majors according to their academic interests and talents. And provide effectiveness and efficiency of teachers in helping majors.

Total absorption γ -ray spectroscopy of the β decays of Y96gs,m

The $\beta$ decays of the ground state (gs) and isomeric state (m) of $^{96}$Y have been studied with the total absorption $\gamma$-ray spectroscopy technique at the Ion Guide Isotope Separator On-Line facility. The separation of the 8$^{+}$ isomeric state from the 0$^{-}$ ground state was achieved thanks to the purification capabilities of the JYFLTRAP double Penning trap system. The $\beta$-intensity distributions of both decays have been independently determined. In the analyses the de-excitation of the 1581.6 keV level in $^{96}$Zr, in which conversion electron emission competes with pair production, has been carefully considered and found to have significant impact on the $\beta$-detector efficiency, influencing the $\beta$-intensity distribution obtained. Our results for $^{96\text{gs}}$Y (0$^+$) confirm the large ground state to ground state $\beta$-intensity probability, although a slightly larger value than reported in previous studies was obtained, amounting to $96.6_{-2.1}^{+0.3}\%$ of the total $\beta$ intensity. Given that the decay of $^{96\text{gs}}$Y is the second most important contributor to the reactor antineutrino spectrum between 5 and 7 MeV, the impact of the present results on reactor antineutrino summation calculations has been evaluated. In the decay of $^{96\text{m}}$Y (8$^{+}$), previously undetected $\beta$ intensity in transitions to states above 6 MeV has been observed. This shows the importance of total absorption $\gamma$-ray spectroscopy measurements of $\beta$ decays with highly fragmented de-excitation patterns. $^{96\text{m}}$Y (8$^{+}$) is a major contributor to reactor decay heat in uranium-plutonium and thorium-uranium fuels around 10 s after fission pulses, and the newly measured average $\beta$ and $\gamma$ energies differ significantly from the previous values in evaluated databases (...)

An Improved Electromechanical Oscillation-Based Inertia Estimation Method

The existing inertia estimation based on electromechanical oscillation relies on a single mode, which is limited in complex systems. In this letter, the inertia is estimated without worrying about the number of modes in the oscillation. The inertia expression is derived based on the swing equation in the frequency domain, which considers the mode coupling in the electromechanical bandwidth using a summation calculation. The effectiveness of the proposed inertia estimation method is validated through simulation data and real measurements.

Reintubation Summation Calculation: A Predictive Score for Extubation Failure in Critically Ill Patients.

ObjectiveTo derive and validate a multivariate risk score for the prediction of respiratory failure after extubation.Patients and methodsWe performed a retrospective cohort study of adult patients admitted to the intensive care unit from January 1, 2006, to December 31, 2015, who received mechanical ventilation for ≥48 h. Extubation failure was defined as the need for reintubation within 72 h after extubation. Multivariate logistic regression model coefficient estimates generated the Re-Intubation Summation Calculation (RISC) score.ResultsThe 6,161 included patients were randomly divided into 2 sets: derivation (n = 3,080) and validation (n = 3,081). Predictors of extubation failure in the derivation set included body mass index <18.5 kg/m2 [odds ratio (OR), 1.91; 95% CI, 1.12–3.26; P = 0.02], threshold of Glasgow Coma Scale of at least 10 (OR, 1.68; 95% CI, 1.31–2.16; P < 0.001), mean airway pressure at 1 min of spontaneous breathing trial <10 cmH2O (OR, 2.11; 95% CI, 1.68–2.66; P < 0.001), fluid balance ≥1,500 mL 24 h preceding extubation (OR, 2.36; 95% CI, 1.87–2.96; P < 0.001), and total mechanical ventilation days ≥5 (OR, 3.94; 95% CI 3.04–5.11; P < 0.001). The C-index for the derivation and validation sets were 0.72 (95% CI, 0.70–0.75) and 0.72 (95% CI, 0.69–0.75). Multivariate logistic regression demonstrated that an increase of 1 in RISC score increased odds of extubation failure 1.6-fold (OR, 1.58; 95% CI, 1.47–1.69; P < 0.001).ConclusionRISC predicts extubation failure in mechanically ventilated patients in the intensive care unit using several clinically relevant variables available in the electronic medical record but requires a larger validation cohort before widespread clinical implementation.

Quantitative Assessment of Burner Flame Stability Through Digital Image Processing

Flame stability is a well-known problem in the power industry where low quality fuel is fired and combustion conditions change rapidly. Unstable flames often lead to lower combustion efficiency, higher pollutant emissions, and other operational problems. Although there are many methods available for flame monitoring and characterisation, very few are suitable for flame stability monitoring. This paper presents a method for the quantification of flame stability by introducing a term called flame stability index through digital imaging and image processing. This index combines variability of several characteristic parameters of a flame. The stability index of a premixed methane-air flame for the equivalence ratio ranging from 0.36 to 2.17 and methane-biomass flames for ten biomass fuels is measured on a laboratory-scale combustion test rig. For purpose of comparison the flame stability is also measured in terms of oscillation frequency and with two earlier methods. Results show that correlation coefficient between the stability index and the oscillation frequency is greater than 0.89, indicating that the stability index characterises the flame stability. In addition, the stability index is more sensitive to the variation in flame stability than the oscillation frequency and its quantification requires a shorter data length. The proposed method outperforms the other two earlier methods, although the latter also combines characteristic parameters of the flame through summation or mean-square calculation. Unlike the earlier methods, the stability index determined using the proposed methods is capable of quantifying flame stability regardless of combustion conditions.

Energy dependent calculations of fission product, prompt, and delayed neutron yields for neutron induced fission on 235U, 238U, and 239Pu

ABSTRACT We perform energy-dependent calculations of independent and cumulative fission product yields for , , and in the first chance fission region. Starting with the primary fission fragment distributions taken from available experimental data and analytical functions based on assumptions for the excitation energy and spin-parity distributions, the Hauser-Feshbach statistical decay treatment for fission fragment de-excitation is applied to more than 1,000 fission fragments for the incident neutron energies up to 5 MeV. The calculated independent yields are then used as an input of -decay calculations to produce the cumulative yield, and summation calculations are performed. Model parameters in these procedures are adjusted by applying the Bayesian technique at the thermal energy for and and in the fast energy range for . The calculated fission observable quantities, such as the energy-dependent cumulative yields, and prompt and delayed neutron yields, are compared with available experimental data. We also study the possible impact of the second chance fission opening on the energy dependence of the delayed neutron yield by on the opening of second chance fission on the energy dependence calculation.

Extensive Study of the Quality of Fission Yields from Experiment, Evaluation and GEF for Antineutrino Studies and Applications

The understanding of the antineutrino production in fission and the theoretical calculation of the antineutrino energy spectra in different, also future, types of fission reactors rely on the application of the summation method, where the individual contributions from the different radioactive nuclides that undergo a beta decay are estimated and summed up. The most accurate estimation of the independent fission-product yields is essential to this calculation. This is a complex task because the yields depend on the fissioning nucleus and on the energy spectrum of the incident neutrons.In the present contribution, the quality of different sources of information on the fission yields is investigated, and the benefit of a combined analysis is demonstrated. The influence on antineutrino predictions is discussed.In a systematic comparison, the quality of fission-product yields emerging from different experimental techniques is analyzed. The traditional radiochemical method, which is almost exclusively used for evaluations, provides an unambiguous identification in Z and A, but it is restricted to a limited number of suitable targets, is slow, and the accuracy suffers from uncertainties in the spectroscopic nuclear properties. Experiments with powerful spectrometers, for example at LOHENGRIN, provide very accurate mass yields and a Z resolution for light fission products from thermal-neutron-induced fission of a few suitable target nuclei.On the theoretical side, the general fission model GEF has been developed. It combines a few general theorems, rules and ideas with empirical knowledge. GEF covers almost all fission observables and is able to reproduce measured data with high accuracy while having remarkable predictive power by establishing and exploiting unexpected systematics and hidden regularities in the fission observables. In this article, we have coupled for the first time the GEF predictions for the fission yields to fission-product beta-decay data in a summation calculation of reactor antineutrino energy spectra. The first comparisons performed between the spectra from GEF and those obtained with the evaluated nuclear databases exhibited large discrepancies that highlighted the exigency of the modelisation of the antineutrino spectra and showing their usefulness in the evaluation of nuclear data. Additional constraints for the GEF model were thus needed in order to reach the level of accuracy required by the antineutrino energy spectra. The combination of a careful study of the independent isotopic yields and the adjunction of the LOHENGRIN fission-yield data as additional constraints led to a substantially improved agreement between the antineutrino spectra computed with GEF and with the evaluated data. The comparison of inverse beta-decay yields computed with GEF with those measured by the Daya Bay experiment shows the excellent level of predictiveness of the GEF model for the fundamental or applied antineutrino physics.The main results of this study are:–an improved agreement between the antineutrino energy spectra obtained with the newly tuned GEF model and the JEFF-3.1.1 and JEFF-3.3 fission yields for the four main contributors to fission in standard power reactors;–indications for shortcomings of mass yields for 241Pu(nth, f) and other systems in current evaluations;–a demonstration of the benefit from cross-checking the results of different experimental approaches and GEF for improving the quality of nuclear data;–an analysis of the sources of uncertainties and erroneous results from different experimental approaches;–the capacity of GEF for predicting the fission yields (and other observables) in cases (in terms of fissioning systems and excitation energies) which are presently not accessible to experiment;–predictions of antineutrino energy spectra that aim to assess the prospects for reactor monitoring, and based on the GEF fission yields associated with the beta-decay data of the most recent summation model.

Impact of the Most Recent Total Absorption Gamma-ray Spectroscopy Data for Fission Fragments on Reactor Antineutrino Spectra and Comparison with the Daya Bay Results

The accurate determination of reactor antineutrino spectra is still a challenge. In 2017 the Daya Bay experiment has measured the evolution of the antineutrino flux with the fuel content of the reactor core. The observed deficit of the detected flux compared with the predictions of the conversion model was almost totally explained by the data arising from the fissions of 235U while the part dominated by the fission of 239Pu was in good agreement with the conversion model. The TAGS collaboration has carried out two experimental campaigns during the last decade at the JYFLTRAP of Jyväskylä (Finland) measuring a large set of data in order to improve the quality of the predictions of our summation method. These measurements allow the correction of the nuclear data for the Pandemonium effect, thus making an important contribution to calculating the antineutrino spectra. The impact of these ten years of measurement from our collaboration on the predicted antineutrino energy spectrum and flux are shown using our summation calculations. The results are compared with the Daya Bay measurements showing the best agreement in shape (in the antineutrino energy range 2 to 5 MeV) and in flux obtained so far with a model. The flux deficit observed by Daya Bay with respect to the summation method is now reduced to 1.9% leaving little room for the reactor anomaly. The shape anomaly between 5 and 7 MeV in antineutrino energy is still observed and remains unexplained.

Disentangling decaying isomers and searching for signatures of collective excitations in β decay

In this contribution we summarize the recent study of the β decay of neutron-rich nuclei with isomeric states close in energy to the ground states. The disentanglement of each pair of β-decaying states was achieved by applying different strategies and using the purification capabilities of the JYFLTRAP double Penning trap system at the Ion Guide Isotope Separator On-Line facility in Jyväskylä. The Total Absorption γ-ray Spectroscopy technique was employed to determine the β intensity probabilities populating the excited states in the daughter nuclei. Previously undetected β intensity was found and we have already evaluated the impact of part of these results on reactor summation calculations. The possibility to populate states associated with the Pygmy Dipole Resonance in the β decay of 96gsY has also been investigated thanks to the sensitivity of our technique to high-lying strength in the daughter nuclei.

Mapping reactor neutrino spectra from TAO to JUNO

The Jiangmen Underground Neutrino Observatory (JUNO) project aims at probing, at the same time, the two main frequencies of three-flavor neutrino oscillations, as well as their interference related to the mass ordering (normal or inverted), at a distance of ~53 km from two powerful reactor complexes in China, at Yangjiang and Taishan. In the latter complex, the unoscillated spectrum from one reactor core is planned to be closely monitored by the Taishan Antineutrino Observatory (TAO), expected to have better resolution (x 1/2) and higher statistics (x 30) than JUNO. In the context of neutrino energy spectra endowed with fine-structure features from summation calculations, we analyze in detail the effects of energy resolution and nucleon recoil on observable event spectra. We show that a model spectrum in TAO can be mapped into a corresponding spectrum in JUNO through appropriate convolutions. The mapping is exact in the hypothetical case without oscillations, and holds to a very good accuracy in the real case with oscillations. We then analyze the sensitivity to mass ordering of JUNO (and its precision oscillometry capabilities) assuming a single reference spectrum, as well as bundles of variant spectra, as obtained by changing nuclear input uncertainties in summation calculations from a publicly available toolkit. We show through a chi-squared analysis that variant spectra induce little reduction of the sensitivity in JUNO, especially when TAO constraints are included. Subtle aspects of the statistical analysis of variant spectra are also discussed.

Comparison of various methods of effective heat summation calculations in viticulture

Antalya ekolojik koşullarında yetiştirilen 34 üzüm çeşidinin uyanma-olgunluk dönemine ait etkili sıcaklık toplamı (EST) istekleri değişik yöntemlerle belirlenmiştir. Her bir çeşit için saatlik, minimum, maksimum ve meteorolojik rasattaki sıcaklıkların esas alındığı 4 farklı günlük ortalama sıcaklık (GOS) değeri hesaplama yöntemine göre EST isteklerindeki değişim incelenmiştir. Bazı çeşitlerin EST istekleri farklı ekolojilerde elde edilen değerler ile karşılaştırılmıştır. Üzüm çeşitleri içerisinde en düşük EST isteği Early Sweet çeşidinde saptanmıştır. Bu çeşidin farklı GOS hesaplamaları için Winkler indisine göre saptanan EST isteği 912-954 derece gün (dg) arasında değişmiştir. Bu çeşidin farklı yöntemlere göre hesaplanan EST isteği ise en düşük 925 dg, en yüksek 983 dg olarak saptanmıştır. Farklı GOS hesaplaması ve farklı yöntemlerin kullanılması çeşitlerin EST isteklerinde değişik düzeylerde farklılıklara yol açmıştır. Sonuç olarak GOS değerlerinin hesaplanmasında yöntemler arasındaki korelasyonun oldukça yakın olduğu, hesaplamalarda 24 saatlik ortalamanın alınmasının daha uygun olacağı fakat bunun temin edilemediği durumlarda diğer yöntemlerin kullanılmasının da çok önemli yanılgıya yol açmayacağı belirlenmiştir. Ayrıca, çeşitlerin EST isteklerinin saptanmasında, saatlik GOS değerleri kullanılarak Winkler indisi formülüne göre hesaplamanın daha uygun olacağı kararına varılmıştır.

New delayed neutron group constants and covariances for LWR core applications, combining summation calculations and integral experiments

New delayed neutron group constants and covariances for LWR core applications, combining summation calculations and integral experiments

Total absorption γ -ray spectroscopy of the β -delayed neutron emitters I137 and Rb95

The decays of the $\beta$-delayed neutron emitters $^{137}$I and $^{95}$Rb have been studied with the total absorption $\gamma$-ray spectroscopy technique. The purity of the beams provided by the JYFLTRAP Penning trap at the ion guide isotope separator on-line facility in Jyv\"askyl\"a allowed us to carry out a campaign of isotopically pure measurements with the decay total absorption $\gamma$-ray spectrometer, a segmented detector composed of eighteen NaI(Tl) modules. The contamination coming from the interaction of neutrons with the spectrometer has been carefully studied, and we have tested the use of time differences between prompt $\gamma$-rays and delayed neutron interactions to eliminate this source of contamination. Due to the sensitivity of our spectrometer, we have found a significant amount of $\beta$-intensity to states above the neutron separation energy that de-excite by $\gamma$-rays, comparable to the neutron emission probability. The competition between $\gamma$ de-excitation and neutron emission has been compared with Hauser-Feshbach calculations, and it can be understood as a nuclear structure effect. In addition, we have studied the impact of the $\beta$-intensity distributions determined in this work on reactor decay heat and reactor antineutrino spectrum summation calculations. The robustness of our results is demonstrated by a thorough study of uncertainties, and with the reproduction of the spectra of the individual modules and the module-multiplicity gated spectra. This work represents the state-of-the-art of our analysis methodology for segmented total absorption spectrometers.

Total absorption γ -ray spectroscopy of niobium isomers

The $\beta$ intensity distributions of the decays of $^{100\text{gs},100\text{m}}$Nb and $^{102\text{gs},102\text{m}}$Nb have been determined using the Total Absorption $\gamma$-Ray Spectroscopy technique. The JYFLTRAP double Penning trap system was employed to disentangle the isomeric states involved, lying very close in energy, in a campaign of challenging measurements performed with the Decay Total Absorption $\gamma$-ray Spectrometer at the Ion Guide Isotope Separator On-Line facility in Jyv\"askyl\"a. The low-spin isomeric state of each niobium case was populated through the decay of the zirconium parent, that was treated as a contaminant. We have applied a method to extract this contamination, and additionally we have obtained $\beta$ intensity distributions for these zirconium decays. The $\beta$-strength distributions evaluated with these results were compared with calculations in quasiparticle random-phase approximation, suggesting a prolate configuration for the ground states of $^{100,102}$Zr. The footprint of the Pandemonium effect was found when comparing our results for the analyses of the niobium isotopes with previous decay data. The $\beta$-intensities of the decay of $^{102\text{m}}$Nb were obtained for the first time. A careful evaluation of the uncertainties was carried out, and the consistency of our results was validated taking advantage of the segmentation of our spectrometer. The final results were used as input in reactor summation calculations. A large impact on antineutrino spectrum calculations was already reported and here we detail the significant impact on decay heat calculations.

Large Impact of the Decay of Niobium Isomers on the Reactor ν[over ¯]_{e} Summation Calculations.

Even mass neutron-rich niobium isotopes are among the principal contributors to the reactor antineutrino energy spectrum. They are also among the most challenging to measure due to the refractory nature of niobium, and because they exhibit isomeric states lying very close in energy. The β-intensity distributions of ^{100gs,100m}Nb and ^{102gs,102m}Nb β decays have been determined using the total absorption γ-ray spectroscopy technique. The measurements were performed at the upgraded Ion Guide Isotope Separator On-Line facility at the University of Jyväskylä. Here, the double Penning trap system JYFLTRAP was employed to disentangle the β decay of the isomeric states. The new data obtained in this challenging measurement have a large impact in antineutrino summation calculations. For the first time the discrepancy between the summation model and the reactor antineutrino measurements in the region of the shape distortion has been reduced.

Summation Calculations for Reactor Antineutrino Spectra, Decay Heat and Delayed Neutron Fractions Involving New TAGS Data and Evaluated Databases

Three observables of interest for present and future reactors depend on the β decay properties of the fission products: antineutrinos from reactors, the reactor decay heat and delayed neutron emission. In these proceedings, we present new results from summation calculations of the first two quantities quoted above, performed with evolved independent yields coupled with fission product decay data, from various nuclear data bases or models. New TAGS results from the latest experiment of the TAGS collaboration at the JYFL facility of Jyväskylä will be displayed as well as their impact on the antineutrino spectra and the decay heat associated to fission pulses of the main actinides.

Prompt and Delayed Neutron Emissions and Fission Product Yield Calculations with Hauser-Feshbach Statistical Decay Theory and Summation Calculation Method

We demonstrate the neutron emission and fission product yield calculations using the Hauser–Feshbach Fission Fragment Decay (HF3D) model and β decay. The HF3D model calculates the statistical decay of more than 500 primary fission fragment pairs formed by the neutron induced fission of 235U. In order to calculate the prompt neutron and photon emissions, the primary fission fragment distributions, i.e. mass, charge, excitation energy, spin and parity are deterministically generated and numerically integrated for all fission fragments. The calculated prompt neutron multiplicities, independent fission product yield are fully consistent each other. We combine the β-decay and the summation calculations with the HF3D model calculation to obtain the cumulative fission product yield, decay heat and delayed neutron yield. The calculated fission observables are compared with available experimental data.

Neutron energy dependence of delayed neutron yields and its assessments

ABSTRACT Incident neutron energy dependence of delayed neutron yields of uranium and plutonium isotopes is investigated. A summation calculation of decay and fission yield data is employed, and the energy dependence of the latter part is considered in a phenomenological way. Our calculation systematically reproduces the energy dependence of delayed neutron yields by introducing an energy dependence of the most probable charge and the odd–even effect. The calculated fission yields are assessed by comparison with JENDL/FPY-2011, delayed neutron activities, and decay heats. Although the fission yields in this work are optimized to delayed neutron yields, the calculated decay heats are in good agreement with the experimental data. Comparison of the fission yields calculated in this work and JENDL/FPY-2011 gave an important insight for the evaluation of the next Japanese evaluated nuclear data library (JENDL) .