bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of a total loss of pool water accident in MTR-type research reactors
Authors: Yilmazer A. , Yavuz H. 
Published: December 2013

AbstractIn this study, the transient in which the pool water is lost throughout one or more of the main coolant pipes which are supposed to be broken guillotine-like is investigated for the TR-2 research reactor in Istanbul. The applicability of the methods used for other similar types of research reactors is shown. Decrease of the pool water level until the top of the core, and from the top to the bottom of the core are examined as two successive phases of the accident. Finite difference scheme and integral methods are employed to solve energy equations and the results of both methods are compared. The finite difference solution uses an explicit form for the analysis of the first phase, and a moving boundary approach for the second phase. The integral method is based on the assumption that the temperatures appearing in the energy equations have the same profiles during the transient as the steady state ones. Analyses are done both for nominal and hot channel, and the results of both methods are observed to be in agreement.
Air pollution forecasts of the German Weather Service for IMIS
Authors: Fay B. , Glaab H. , Jacobsen I. , Klein A. 
Published: December 2013

Abstract
The emergency response system of the German Weather Service (Deutscher Wetterdienst – DWD) will be described including the models (trajectories, LPDM), the national (IMIS, RODOS) and international (IAEA, WMO) co-operation. Examples show the performance of the models and the system.
Natural radionuclides in mineral water in Germany
Authors: Obrikat D. , Beyermann M. , Bünger Th. , Viertel H. 
Published: December 2013

Abstract
The activity concentrations of Ra-226, Ra-228, Po-210, Pb-210, U-234, U-235, U-238 and Ac-227 have been determined in approx. 400 bottled mineral waters in Germany. The median value of radiation exposure for children (age 0–1 year, 1701/y) is 0.047 mSv/a. The main part of exposure (80–90% approx.) is caused by the isotopes Ra-226 and Ra-228. The median values of concentrations are 7 mBq/l, respectively. Maximal concentrations up to 370 mBq/l were observed.
Strategy for taking measurements using the German Integrated Measuring and Information System (IMIS) in the case of a nuclear emergency
Authors: Bieringer J. 
Published: December 2013

Abstract
In the case of a nuclear emergency situation, as compared to normal operation, other requirements such as type of information, availability in time and amount must be met in order to characterise the radiological situation and provide recommendations for countermeasures. These requirements are dependent upon the different phases of the emergency. In the beginning phases (Phase 1 and Phase 2) the timely availability of information is of great importance. The focus changes more and more to the diversity of the analysed environmental media in the course of the event. The status at the plant, source term estimates, meteorological data, and weather forecasts are needed in order to calculate trajectories and assessing the prognoses of the expected external dose and contamination during Phase 1 before the release. In addition, on-line dose rate measurements and information on the radionuclide spectrum are necessary. The aim is to get an overview of the actual radiological situation and its possible development in time in order to introduce countermeasures, where necessary. In Phase 2, when the dispersion of radioactivity is finished, measurements according to § 3 of the Precautionary Radiation Protection Act (StrVG) are of primary interest, particularly the determination of contamination to human food and animal feed. During the phase following the deposition, the external dose as a function of time can be well predicted if the nuclide spectrum is known. In Phase 3, i. e. weeks following the emergency, measurements are used to observe the activity concentrations in different media over a longer period of time.
Theoretical studies on thermal stratification in a side heated cavity
Authors: Kumar N. V. Satish , Maheshwari N. K. , Vijayan P. K. , Saha D. , Sinha R. K. 
Published: December 2013

AbstractThe Advanced Heavy Water Reactor (AHWR) being designed in India is a vertical pressure tube type boiling water-cooled and heavy water moderated reactor. A key feature of the AHWR is the use of simple passive systems to respond to any postulated accidental condition. Passive Containment Cooling System (PCCS), is one such system, which provides long term cooling for the reactor containment following a Loss Of Coolant Accident (LOCA). The system consists of Immersed Condensers immersed in a gravity driven water pool. One of the important phenomena related to PCCS functioning is the effect of thermal stratification in the water pool. The heat transfer from IC to water pool takes place by natural convection. In this process, the pool water can get stratified. Towards the top of the water pool, the temperature of water may reach almost the boiling point while at the bottom of the pool, the water is likely to remain at the initial temperature. Hence, in order to study the integral system response of PCCS, the phenomenon of stratification requires to be investigated. Towards this objective, the case of a rectangular enclosure heated symmetrically on both the vertical sides was considered and a two-dimensional analysis was done by numerically solving the mass, momentum and energy equations. Theoretical results were generated by the use of a computer code developed for this purpose and the results are then compared with the experimental results available in literature.
Comments on the question of the discovery of element 112 as early as 1971
Authors: Brandt R. 
Published: December 2013

Abstract
There are two independent claims for the discovery of element 112: The claim by Hofmann et al. from 1996 and the older claim from 1971 by Marinov et al. This Comment will not challenge the experimental results of Hofmann et al., but it will discuss one aspect of the claimed discovery of element 112 by Marinov et al., as their experiment has never been reproduced in exactly the form in which the original experiment has been carried out. The reasons for this deficiency may not be found in the field of science, but possibly in radioprotection restrictions for researchers who want to carry out such an experiment. However, such is not a sufficient reason to exclude the original claim from all considerations of the responsible international authorities, who have to settle such priority questions. It may be in agreement with scientific traditions, that when the responsible international committees do not feel to be able to come to a positive decision on the “1971” claim, they could keep the priority problem unsettled for the time being.
Analysis of future nuclear power plants competitive investment costs with stochastic methods
Authors: Feretic D. , Cavlina N. , Grgic D. 
Published: December 2013

Abstract
One of main issues in planning future power system expansion is forecast of expected electricity generating costs. Due to the fact that the forecast should be extended to plants lifetime it is best to consider and compare lifetime levelized cost of generated electricity for each of the candidate plants. The analysis is a part of studies for the future expansion of the Croatian power system, but is valid generally. The main competitors to nuclear power plants are combined cycle natural gas fired plants whose economy strongly depends upon gas cost. The expected increase of gas cost in following decades can substantially influence the competitiveness of nuclear plants versus gas fired plants. In addition, the costs of electricity produced by coal fired plants and wind electricity generators were also considered. Due to uncertainties of input parameters it is advantageous to use probabilistic instead of deterministic method of analysis. The paper considers the problem of the probabilistic distribution of nuclear power plant investment costs for which such plants could be competitive to gas fired plants for an estimated probable range of gas cost increase rates.
Effects of spectral shifting in an inertial confinement fusion system
Authors: Şahin S. , Şahin H. M. , Yildiz K. , Acir A. 
Published: December 2013

Abstract
The main objective is to study the effects of spectral shifting in an inertial confinement system for kT/shot energy regime on the breeding performance for tritium and for high quality fissile fuel. A protective liquid droplet jet zone of 2 m thickness is used as coolant, energy carrier, and breeder. Flibe as the main constituent is mixed with increased mole-fractions of heavy metal salt (ThF4 or UF4) starting by 2 moles% up to 12 moles%. Spectrum softening within the inertial confinement system reduces the tritium production ratio (TBR) in the protective coolant to a lower level than unity. However, additional tritium production in the 6Li2DT zone of the system increases TBR to values above unity and allows a continuous operation of the power plant with a self-sustained fusion fuel supply. By modest fusion fuel burn efficiencies (40 to 60 %) and with a few mol.% of heavy metal salt in the coolant in form of ThF4 or % UF4, a satisfactory TBR of > 1.05 can be realized. In addition to that, excess fissile fuel of extremely high isotopic purity with a rate of ∼ 1000 kg/year of 233U or 239Pu can be produced. Radiation damage through atomic displacements and helium gas production after a plant operation period of 30 years is very low, namely dpa < 1 and He < 2 ppm, respectively.
Simulation of the hydrogen distribution in the confinement of the Ignalina nuclear power plant
Authors: Babilas E. , Urbonavicius E. , Rimkevicius S. 
Published: December 2013

Abstract
The Accident Localisation System (ALS) of the Ignalina nuclear power plant is a “pressure suppression” type confinement, which protects the population, workers and environment from radiation hazards. According to the safety justification of RBMK-1500 reactors, ∼110 m3 of hydrogen is released to the ALS compartments during a maximum design basis accident. To prevent the possible hydrogen accumulation and combustion, a hydrogen concentration control system is installed. The main goal of the present paper is to present the ALS model for the COCOSYS code and assess the effectiveness of the hydrogen control system of the Ignalina nuclear power plant. The analysis performed identified locations of possible hydrogen accumulation in the ALS compartments during the transient processes and assessed the mixture combustibility in these locations for a maximum design basis accident scenario.
ICDE-results on complete common cause failures in the light of results obtained with the POS model
Authors: Berg H. P. , Fröhmel T. , Görtz R. , Kesten J. , Weil L. 
Published: December 2013

Abstract
Since April 1998, the OECD Nuclear Energy Agency (NEA) is operating the International Common Cause Data Exchange (ICDE) project. The objectives of this exchange comprise, to collect and analyze CCF events, to generate insights into root causes and derive preventing approaches, to strengthen experience feedback and, last but not least, to facilitate quantification. For a large number of about 1000ICDE events the fractions of complete CCFs have been displayed as a function of the degree of redundancy. Complete CCFs are relevant to PSA as in these cases the respective function fails and in many cases significant contributions to core damage can be expected. From the point of view of quantitative CCF modeling, the theoretical theoretical approach to of the empirically available complete CCF fractions represents a major challenge. The large number of events have been collected in the ICDE project for nine different types of components in nuclear power plants from ten different countries. Obviously, these components are operated under different conditions and technical specifications. Therefore, an approach is chosen which is based on low information distributions of the model parameters to account for the large variation throughout the component populations. The Process Oriented Simulation Model (POS) has been selected to carry out an analysis of complete CCFs. The consistency between the theoretical approach – considering its simplicity – and the data observed is satisfactory.
Analytical study of the closure flow inside the ETRR-2 core chimney
Authors: El-Morshdy S. El-Din 
Published: December 2013

Abstract
The present work is carried out in order to study the closure flow inside the core chimney of the Egypt Second Research Reactor (ETRR-2). Based on the finite difference technique, a two dimensional model is developed to simulate the coolant flow inside the chimney. The model is verified by FEHT finite element program. Then a study of different closure flow values inside the chimney was made using the developed model where a flow map is plotted showing the stagnation depth for each closure flow. The flow map shows that for a closure flow greater than 0.16 m3/h, no active water ascends from the core to the pool through the chimney. The model results are analyzed and discussed.
Incineration of weapon grade plutoniumin a (DT) fusion driven hybrid reactor using various coolants
Authors: Übeyli M. , Acır A. 
Published: December 2013

Abstract
Reducing separated weapon grade (WG) plutonium is very crucial since this plutonium may be misused and/or released accidentally into the environment. Burning WG plutonium in nuclear reactors can help to solve this serious problem effectively. In this study, the incineration of WG plutonium mixed with thorium in a (DT) fusion driven high power density hybrid reactor was investigated for an operation period of 24 months. Furthermore, the effect of using different coolants on the burning of WG plutonium in the hybrid blanket was examined. Numerical calculations showed that WG plutonium can be denatured to reactor grade level within a very short time by using a high power density hybrid reactor. Moreover, addition of WG plutonium to thorium improved the neutronic performance of the reactor significantly.
Calculation of the pin power distribution for a thorium reactor assembly and benchmarking
Authors: Aziz M. 
Published: December 2013

Abstract
A computer model was developed to perform neutronic and burn-up analysis for an assembly of a thorium reactor. The MCNP computer code was used to model the geometry of the assembly and to determine both, the power and flux distribution. A system of ordinary differential equations which represents all fuel isotopes was solved numerically to evaluate the time behavior of fuel composition and burn-up. The results of the present model were compared with the solutions of benchmark problems and satisfactory agreement was found.
Thermal-hydraulic modeling of reactivity accidents in MTR reactors
Authors: Khater H. , Abu-El-Maty T. , El-Morshdy S. El-Din 
Published: December 2013

Abstract
This paper describes the development of a dynamic model for the thermal-hydraulic analysis of MTR research reactor during a reactivity insertion accident (RIA). The model is formulated for coupling reactor kinetics with feedback reactivity and the reactor core thermal-hydraulics. Two channels are considered; the average and the hot channels to represent the reactor core. The developed computer program is compiled and executed on a personal computer using the FORTRAN language. The model is validated by safety-related benchmark calculations for MTR-TYPE reactors of IAEA 10 MW generic reactor for both slow and fast reactivity insertion transients. A good agreement is shown between the present model and the benchmark calculations. The model is used for simulating uncontrolled withdrawal of a control rod for the ETRR-2 reactor in transient with over power scram trip. The simulation results for the ETRR-2 are analyzed and discussed.
Prediction of the onset of flow instability in the ETRR-2 research reactor under loss of flow accident
Authors: Khater H. A. , El-Morshdy S. El-Din , Ibrahim M. M. A. 
Published: December 2013

Abstract
In the present work, prediction of the onset of flow instability (OFI) in Egypt's second Research Reactor (ETRR-2) under loss of flow accident (LOFA) conditions due to loss of off-site power has been performed based on the model developed in previous work. Calculations are performed for LOFA with Scram due to low flow signal at 90% of the nominal flow where the time length that covers this transient is 4.8 seconds. Both, the best-estimate and conservative calculations are performed under the specified operating conditions and geometrical data of ETRR-2 for both, exponential and ramp pressure gradient change. The OFI locus is predicted and plotted against the flow velocity, exit coolant temperature and bubble detachment parameter for several heat fluxes. The results are analyzed and assessed in order to obtain the safety margins for OFI phenomenon that measure how far the operating conditions are from the OFI locus. It is found that, the safety margins for OFI phenomenon in the best-estimate calculation are 2.62 and 2.35 for steady state and LOFA transient respectively, while its values in the conservative calculation are 1.68 and 1.47, respectively.
Application of the U

N
method to the reflected critical slab problem for one-speed neutrons with forward and backward scattering
Authors: Öztürk H. , Anlı F. , Güngör S. 
Published: December 2013

Abstract
The UN method is used to solve the critical slab problem for reflecting boundary conditions in one-speed neutron transport theory. The isotropic scattering kernel with the combination of forward and backward scattering is chosen for the neutrons in a uniform finite slab. It is shown that the method converges rapidly with easily executable equations. The presented numerical results are compared with the results available in the literature.
The OECD FIRE database
Authors: Angner A. , Berg H. P. , Röwekamp M. , Werner W. , Gauvain J. 
Published: December 2013

Abstract
Realistic modelling of fire scenarios is still difficult due to the scarcity of reliable data needed for deterministic and probabilistic fire safety analysis. Therefore, it has been recognized as highly important to establish a fire event database on an international level. In consequence, several member countries of the Nuclear Energy Agency of the OECD have decided in 2000 to establish the International Fire Data Exchange Project (OECD FIRE) to encourage multilateral co-operation in the collection and analysis of data related to fire events at nuclear power plants. This paper presents the OECD FIRE project objectives, work scope and current status of the OECD FIRE database after 3 years of operation as well as first preliminary statistical insights gained from the collected data.
Characterization of dose rate instruments for environmental radiation monitoring
Authors: Wissmann F. , Rupp A. , Stöhlker U. 
Published: December 2013

Abstract
Any dose rate instrument used to monitor environmental radiation must be characterized with respect to its response to secondary cosmic radiation and terrestrial radiation. This requires calibrations using different photon radiation fields, the measurement of the instruments internal background and the exposure to secondary cosmic radiation. The methods developed within the cooperation between BfS and PTB are explained in detail by an intercomparison of instruments which are part of the German early warning network IMIS and a high-pressure ionization chamber which was used as the reference instrument. The measurements were performed at the PTB facilities for the dosimetry of environmental radiation. It is shown how the ambient dose equivalent rate of the terrestrial radiation is determined and how the sensitivity of an instrument to a radioactive cloud passing by can be investigated.
Axial flux harmonics affecting the parallel channel instabilities in boiling water reactors
Authors: Aktaş D. , Geçkinli and M. 
Published: December 2013

Abstract
The existence of boiling phenomena in boiling water-reactors makes these systems susceptible to instabilities. Neutronics coupled with the thermal-hydraulics complicate the problem further. Boiling water reactor instabilities are classified as global or local according to the spatial dependency of the power fluctuations. At present, numerical codes can simulate these instabilities rather well on event basis; but more general physical insight can be gained readily through analytical modeling. One of the earliest models applied to the problem is the parallel channel instability, so called because of the applied thermohydraulic boundary conditions. In this work a new type of instability model is proposed and studied by including the effect of the first axial harmonic of the flux. Thermal-hydraulics is represented with one-dimensional two-phase homogeneous equilibrium flow model equations. Analysis is performed with linearized equations in the frequency domain. Special emphasis is given to the motion of the boiling boundary. The results clearly indicate that the first axial harmonic of the flux affects the stability of the reactor adversely, and must be accounted for to make more realistic predictions.
Uncontrolled withdrawal of a control rod without SCRAM
Authors: Abou-El-Maaty T. 
Published: December 2013

Abstract
In the present work, the thermal-hydraulic analysis of reactivity-induced transients in a Low Enriched Uranium (LEU) core of a typical material test research reactor is conducted using the previous program developed Khater et al. The analysis was done for the uncontrolled withdrawal of a control rod under scram-disabled conditions. The initiating event reactivity was considered with and without influence of the reactivity efficiency curve (“S” curve). The results of the transient calculations are analyzed and compared with each other. In the transient without the “S” curve influence, a high primary peak power of 406.18 MW is attained and a clad melt down is occurring after 1.85 s. In the transient with the “S” curve influence, a super prompt highly critical situation is produced (1.762 $ at 0.895 s) with a very high primary peak power of 801.05 MW at 0.912 s. A fast clad melt down is resulting in the hot channel at 1.088 s and a stable film boiling is occurring. This study shows that the influence of the reactivity efficiency curve results in higher peaks in power and temperatures (fuel, clad and coolant) with a fast clad melt down than that of a linear assumption.
Unified treatment of the P
(λ)

n
approximation to solve the reflected slab criticality problem with strong anisotropy
Authors: Yılmazer A. , Tombakoglu M. 
Published: December 2013

Abstract
Ultraspherical polynomial P
(λ)

n
approximations are used in reflected slab criticality calculations for strongly anisotropic scattering. A unique formulation is developed for reflected slab criticality conditions whose special cases are spherical harmonics approximations, Chebyshev polynomial approximations of first and second kind. It is shown in the calculations that all ultraspherical polynomial approximations are equivalent regarding the convergence of the solution of one-speed neutron transport equation for various degrees of anisotropy and cross section parameters. Although some ultraspherical polynomials approximations converge in the mean as the order of approximation is increased and some converge uniformly, they all converge to the same critical thickness which implies their equi-convergence. It is also demonstrated that the first order approximation P
(λ)
1 would give the exact critical thickness for a certain value of the parameter λ.