bluuebunny/crossref_metadata_2025_split huggingface dataset:
Is mapping a part of common cause failure quantification?
Authors: Vaurio J. K. 
Published: December 2013

Abstract
Important issues in any procedure used for estimating basic event probabilities of common cause failures (CCF) for probabilistic safety assessments (PSA) are: which plants and systems to use, how to combine them, and how to transform data from systems with different numbers of similar components to obtain CCF-rates for a specific group of components. These issues are addressed with focus on the last part called “mapping”. Certain parametric models are considered for transforming CCF event experience from data-source plants to the target plant, the plant of interest. Two sets of rules are reviewed and compared for transforming rates and assessment uncertainties from larger to smaller systems i.e. mapping down. Epistemic uncertainties are taken into account in the estimation. Mapping down equations are presented also for the alpha-factors and for the variances of CCF-rates. Consistent rules are developed for mapping up CCF-rates, uncertainties and alpha factors from smaller to larger systems. These rules are not limited to a binomial CCF model. Consistency requirements are severe and dictate certain limits to possible parametric values. Empirical alpha factors are used to quantify robust mapping ratios of complete CCF-rates. Mapping is critically analyzed and practical recommendations are made.
Experiments and comparing calculations on thermohydraulic pressure surges in pipes
Authors: Neuhaus T. , Dudlik A. 
Published: December 2013

Abstract
Modelling of pressure surges in power plant pipe systems means to carefully judge and classify the relevant variables. A decision must be made, whether the numerous effects that can occur during a transient event, should be modelled. One main point is to determine if fluid structure interaction (FSI) is important for the special situation/scenario. Also unsteady friction and degassing of dissolved gases can occur. But with each model more sources of errors are introduced into the mathematical system, such as uncertainty about bearing clearance, determination of fixing points/stiffness/spring constants, determination of friction coefficients and damping parameters, uncertainty about the amount of non-condensables in the liquid, dynamics of de-aeration processes and unsteady friction coefficients. Another complicated problem is the definition of boundaries, like specifications of pumps, valves, fittings, etc. It is obvious that a combination of all uncertainties may lead to quite uncertain predictions and must therefore be very carefully taken into account. Within this contribution, valve-closing experiments of different initial temperature and system pressure at Fraunhofer test rig PPP are presented. Two scenarios are modelled using different assumptions and model depths and the simulation results are compared with experimental data.
Irradiation damages in tantalum spallation target
Authors: Villagrasa-Roussel C. , Broeders C. H. M. , Konobeyev A. Yu. 
Published: December 2013

Abstract
The irradiation by a high intensity proton beam of the spallation target in Accelerator Driven Systems (ADS) gives rise to structural damages that must be considered in the design and handling of such materials. In this work, some of these damages are evaluated in the case of the irradiation of a tantalum target. Tantalum was recently proposed as solid target in the case of low power systems. Unfortunately, not enough experimental data of spallation reactions in this material are available. Therefore, our calculations were made using MCNPX and the stand-alone version of the spallation codes INCL4+ABLA. Results of this work are the concentrations of spallation residues produced in the target after one year of irradiation and calculations of the activity derived. Also displacements per atom in the target material have been evaluated. Different components (elastic scattering and non-elastic reactions) of the displacement cross-sections were calculated with two different methods.
An interpretation procedure for the purpose of incorporation monitoring during decommissioning of nuclear reactors
Authors: Schupfner R. , Haas G. , Wolfbeis O. , Dettmann K. 
Published: December 2013

Abstract
The incorporation monitoring during decommissioning of nuclear reactors is faced with a complex situation arising from a mixture of radionuclides. The development of an interpretation procedure to enable the application of an optimised incorporation monitoring on conditions of decommissioning of nuclear reactors has been carried out combining results from radionuclide analyses of contaminated or activated materials and the proven methods of incorporation monitoring in the case of the intake of single radionuclides. In this study the radiological requirements, the mathematical elements of the interpretation procedure are presented as well as the application to an activated concrete of biological shielding.
Thermal hydraulics of the fixed bed nuclear reactor concept
Authors: Sefidvash F. 
Published: December 2013

Abstract
The thermo-hydraulics of the fixed bed nuclear reactor (FBNR), possessing spherical HTGR type fuel, is described. Its main characteristic is the variable fixed bed core in suspense and its “cold” fuel in case of a LOCA (< 400°C). A 40 MWel reactor has a pressure loss across the fixed bed of 9.5 bar and needs a pump power of 3.4 MWel – more than in a classical PWR but being the price for its excellent inherent safety characteristics.
The critical slab problem for linearly anisotropic scattering and reflecting boundary conditions with the HN method
Authors: Güleçyüz M. Ç. , Türeci R. G. , Tezcan C. 
Published: December 2013

Abstract
The HN method is used to calculate the critical slab thickness for a parallel media surrounded bay a reflector for linearly anisotropic scattering. It is shown that the method leads to concise equations and accurate numerical results even in the lowest order of approximation.
The multipurpose thermalhydraulic test facility TOPFLOW: an overview on experimental capabilities, instrumentation and results
Authors: Prasser H.-M. , Beyer M. , Carl H. , Manera A. , Pietruske H. , Schütz P. , Weiß F.-P. 
Published: December 2013

Abstract
A new multipurpose thermalhydraulic test facility TOPFLOW (TwO Phase FLOW) was built and put into operation at Forschungszentrum Rossendorf in 2002 and 2003. Since then, it has been mainly used for the investigation of generic and applied steady state and transient two phase flow phenomena and the development and validation of models of Computational Fluid Dynamic (CFD) codes in the frame of the German CFD initiative. The advantage of TOPFLOW consists in the combination of a large scale of the test channels with a wide operational range both of the flow velocities as well as of the system pressures and temperatures plus finally the availability of a special instrumentation that is capable in high spatial and temporal resolving two phase flow phenomena, for example the wire-mesh sensors.
Effect of packing fraction variations on the multiplication factor in pebble-bed nuclear reactors
Authors: Snoj L. , Ravnik M. 
Published: December 2013

Abstract
The effect of fuel element packing density on the effective multiplication factor, keff, in a typical pebble-bed reactor (PBR) is studied using MCNP and WIMS computer codes. It is observed that at normal operating conditions keff increases with packing density. Increase in packing density of 1% results in approximately 0.0015 increase in keff. A negative temperature effect is observed at all feasible packing densities. The effect of secondary coolant (water) ingress in the core at accidental conditions is studied at various packing densities. The effect of effective water density on keff depends on packing fraction, fuel enrichment and fuel-to-graphite ratio. It is strongly positive in highly enriched fuel at low water density regardless of packing fraction. For fuel enrichment 8% and normal packing density, a maximum positive effect of approximately +0.10 on keff is observed at a water density of ∼0.1 g/cm3. The positive effect is reduced at low enrichments. Above a water density of 0.5 g/cm3, the effect on keff becomes negative regardless of enrichment and packing density.
Modeling of the TOSQAN test facility with the lumped parameter code COCOSYS
Authors: Babilas E. , Urbonavicius E. , Rimkevicius S. 
Published: December 2013

Abstract
Hydrogen distribution in the containment during severe accidents is an important safety issue of nuclear power plants operation. The detailed knowledge of the containment thermal-hydraulics is necessary for reliable predictions of pressure, temperature and gas distribution in the containment of the NPP during postulated accidents. For this purposes, the study of the International Standard Problem (ISP 47) has been started in 1999 with the test facilities TOSQAN, MISTRA and ThAI. The paper presents the COCOSYS nodalisation of the TOSQAN test facility. The results are analysed and compared with the experimental values.
Analytical and experimental investigations of shear stress in rod bundles with irregular cells
Authors: Cesna B. 
Published: December 2013

Abstract
The paper presents analytical and experimental investigations of shear stress on the rods of a bundle with irregular arrays. Simplified, however, effective methodologies are developed for thermal hydraulic processes (shear stress on the bundle rods' surfaces) along the multi-rod bundles. A single-vortex transfer gradient model is recommended taking into account the calculation results and a number of referenced experimental works. Analytical calculation methodologies of shear stress are based on ordinary differential equations and implemented in the computer codes RKN and RKN-M. Concurrently with the analytical investigations, experimental works were performed to determine the shear stress on the rods in a bundle with irregular cells. The results of the calculations are compared with experimental data.
Time-dependent albedo problem for quadratic anisotropic scattering
Authors: Türeci R. G. , Türeci D. 
Published: December 2013

Abstract
Case's eigenfunctions and their orthogonality relations can be improved assuming pure-quadratic anisotropic neutron scattering. As a result, the infinite medium Green function can be written with those eigenfunctions terms. Choosing the appropriate boundary conditions and using the method of singular eigenfunctions, the half-space values are obtained. Our numerical results for this problem are reported.
European approach to nuclear and radiological emergency management and rehabilitation strategies (EURANOS)
Authors: Raskob W. 
Published: December 2013

Abstract
The 5-year multi-national project EURANOS, funded by the European Commission and 23 European Member States, started in April 2004. Integrating 17 national emergency management organisations with 33 research institutes, it brings together best practice, knowledge and technology to enhance the preparedness for Europe's response to any radiation emergency and long-term contamination. Key objectives of the project are to collate information on the likely effectiveness and consequences of a wide range of countermeasures, to provide guidance to emergency management organisations and decision makers on the establishment of an appropriate response strategy and to further enhance advanced decision support systems, in particular, RODOS (Real-time On-line Decision Support), through feedback from their operational use. The research activities focused on emergency actions and countermeasures, the enhancement of decision support systems for operational application and the development of strategies for the sustainable rehabilitation of contaminated territories. The demonstration activities exercise the developed methods and tools in the actual operational environment.
Bilateral information and data exchange in case of nuclear emergencies in the German-Dutch border region
Authors: Twenhöfel C. J. W. , Salfeld H. Ch. , Hable K. , Reinen H. A. J. M. 
Published: December 2013

Abstract
Communication and exchange of accident information and monitoring data during nuclear emergencies is of crucial importance for a coherent crisis management, especially in cross border regions. In Germany and the Netherlands the need for a reliable information and data exchange for cross border emergency management was recognized and resulted in a Memorandum of Understanding between our countries. A (sub) working group of the Niederländisch-Deutsche Kommission für grenznahe kerntechnische Einrichtungen (NDKK) was formed by NLWKN, BfS and RIVM. The working group reviewed the technical requirements and operational aspects of a coherent data and information exchange between national and federal emergency centers and the state authorities. The data exchange comprises various messages, documents, measurement data and prognostic results from model calculations from the technical decision support centers of NLWKN, BfS and RIVM. Integrated accident information is available on the emergency management websites ELAN (D) and CalWeb (NL). Via regular data exchange programs and exercises special attention is given to ensure long term sustainability of the technical infrastructure and operational data exchange procedures.
Rapid determination of strontium radionuclides in plants, fodder and foodstuffs
Authors: Tait D. , Haase G. , Hartmann R. , Jelinski M. 
Published: December 2013

AbstractThe fission yield, the transfer factors in the food chain and the dose coefficient are large for the nuclear fission product Sr-90. The surveillance of Sr-90 in the food chain is therefore important in precautionary radiation protection and in assessing the radiation dose to the public especially after a nuclear incident. Prior to analysis, as it is a pure β-emitter, Sr must be separated from the sample by procedures which, for complex organic samples, are lengthy, laborious and dependent on operator skill. Ubiquitous natural radionuclides and short-lived fission products in samples contaminated with fresh fallout may interfere. Here we describe a fast, reproducible and effficient method for extracting Sr from grass, clover, maize, wholemeal rye, baby food, and total diet. The method depends on obtaining an ash free of traces of organic interferences. Sr may be separated from a dilute nitric acid leachate of such ash with a solution of dicyclohexyl-18-crown-6 in chloroform. Interfering radionuclides are removed with a special manganese (IV) oxide (active, precipitated from Merck). Sr is precipitated as carbonate then dispersed in a cocktail for liquid scintillation spectrometry. This allows simultaneous counting of Sr-89 (a short-lived β-emitter in fresh fallout) and Sr-90. The chemical yields of Sr determined with the gamma-emitting Sr-85 tracer are reproducible and greater than 75 % in all cases. The sample ashing requires 18 h and the extraction 4.0 to 4.5 h. Thus, a duplicate analysis may be completed within 2 days of receipt of the sample.
Correction of deposition predictions with data assimilation
Authors: Gering F. 
Published: December 2013

Abstract
Model predictions for rapid assessment and prognosis of possible radiological consequences after an accidental release of radionuclides play an important role in nuclear emergency management. Radiological measurements (e. g., dose rate measurements) can be used to improve such model predictions. This paper describes a method for combining model predictions and measurements (data assimilation) in the deposition model of the European radiological decision support system RODOS. The data assimilation approach is based on the Ensemble Kalman Filter, a Monte Carlo variant of the Kalman filter.
Iodine Prophylaxis following nuclear accidents – a concept how to distribute potassium-iodide tablets out of the central stocks in the event of an accident
Authors: Portius U. 
Published: December 2013

Abstract
With its recommendation “Iodine prophylaxis following nuclear accidents” (1996) and its reports of 1997 and 2001 the German Commission on Radiological Protection (SSK) followed the recommendations of the WHO “Guidelines for iodine prophylaxis following nuclear accidents” of 1989. The intervention levels were lowered (50 mSv for children/adolescents (up to the age of 18 years) and pregnant women, 250 mSv for adults), the iodine prophylaxis was restricted to persons up to the age of 45 years and the recommended dosage of stable iodine was changed. Due to the lowered reference levels the radius of 25 km around a nuclear power plant that had been the planning radius for the distribution of iodine tablets so far was extended to 100 km. Based on these recommendations the German authorities began to set up new strategies for the provision and distribution of potassium-iodide tablets (iodine tablets). Since 2004, within the radius of 25 km the iodine tablets are pre-distributed to households and/or stored at several points in the municipality for persons up to the age of 45 years. For the new planning radius of 25 – 100 km iodine tablets are stored in 8 central stocks in Germany for children/adolescents (up to the age of 18 years) and pregnant women. A working group with representatives from federal and Länder authorities has developed a distribution strategy for the distribution out of these central stocks in the event of an accident. It describes a possibility of organising and implementing the distribution of the iodine tablets within the radius of 25 – 100 km in a nationwide standardised way.
The slab albedo and criticality problem for the quadratic scattering kernel with the HN method
Authors: Türeci R. G. , Güleçyüz M. Ç. 
Published: December 2013

Abstract
The one speed, time independent neutron transport equation for slab geometry with quadratic anisotropic scattering kernel is considered. Albedo, transmission factor and criticality thickness are calculated by the HN method. The numerical results obtained are listed for different selected parameters. It is shown that the method is concise and leads to fast converging numerical results.
Study of the effect of anisotropic scattering on the critical slab problem in neutron transport theory using Chebyshev polynomials
Authors: Öztürk H. 
Published: December 2013

Abstract
The effect of anisotropic scattering on the variation of the critical thickness for one-speed neutrons in a uniform finite slab has been studied using Marshak boundary conditions. Chebyshev polynomials of the second kind are used in the angular part of the neutron flux. The critical slab thicknesses are calculated for various values of collision and anisotropy parameters. Numerical results obtained by the present method for the critical thickness are presented in the tables together with the results obtained by Legendre polynomials approximation and the ones available in the literature for comparison.
Analysis of a steam generator tube rupture under realistic initial and boundary conditions
Authors: Sarkadi P. , Schaffrath A. 
Published: December 2013

Abstract
Within the framework of safety analysis the TÜV NORD SysTec GmbH & Co. KG has analyzed a steam generator tube rupture for a pressurized water reactor under realistic initial and boundary conditions. During the accident an undesirable backing of the coolant pressure by switching-on the safety injection pumps is avoided, which can endanger the coolant retention in the steam generators, because the shut off heads of the safety injection pumps are larger than the response pressure of the safety valves.
Application of the Laplace transform method for the albedo boundary conditions in multigroup neutron diffusion eigenvalue problems in slab geometry
Authors: Petersen C. Z. , Vilhena M. T. , Barros R. C. 
Published: December 2013

Abstract
In this paper the application of the Laplace transform method is described in order to determine the energy-dependent albedo matrix that is used in the boundary conditions multigroup neutron diffusion eigenvalue problems in slab geometry for nuclear reactor global calculations. In slab geometry, the diffusion albedo substitutes without approximation the baffle-reflector system around the active domain. Numerical results to typical test problems are shown to illustrate the accuracy and the efficiency of the Chebysheff acceleration scheme.
Training and retraining programme for research reactor operating personnel
Authors: Shokr A. M. , Shaat M. K. 
Published: December 2013

Abstract
This paper addresses the training and retraining programme for research reactor operating personnel. The factors that need to be considered in establishing an effective organizational structure for research reactor operation are discussed as they form the basis for the development of the initial training and retraining programme for the operating personnel. Different elements for a successful implementation of this programme such as training system, materials, and methods are also discussed. Application of these elements to the case of the Egypt Second Research Reactor (ETRR-2), which is a relatively large research reactor, is illustrated. The detailed content of the training programme is presented along with discussions that include the applicability of this programme to smaller research reactors.
Precursor analyses for German nuclear power plants
Authors: Babst S. , Gänssmantel G. , Stück R. 
Published: December 2013

Abstract
Precursor analysis is an internationally recognized method for quantifying the safety-relevance of operational events in nuclear power plants. Precursors are operational events in nuclear power plants which had no serious impact, but which could have led to serious impacts, if additional malfunctions had occurred. Examples of such operational events are component failures or transients, for example, the loss of main feedwater. On the basis of the probabilities for the occurrence of additional malfunctions or initiating events precursor analyses determine the probability with which these additional malfunctions during the event occurred would have led to core damage. This conditional probability is a measure for the safety relevance of the operational event occurred. Events, for which the probability of core damages is > 10–6, are internationally classified as “precursor”.
Early warning against airborne radioactivity in Bavaria: Measuring network for radioactive immissions
Authors: Faleschini J. , Mayer H. , Bielz M. , Hackl W. , Schulz T. 
Published: December 2013

AbstractDuring the Chernobyl accident it became evident that there was no up to date information of the radiological situation in Bavaria as a whole. Therefore an online measuring network was implemented, which provides radioactivity data around the clock from all over Bavaria. It comprises measuring devices for gamma-dose rate, airborne aerosol and iodine activity and precipitation. The data are processed in accessory computers and transferred to the main network computers in Augsburg by means of a subcenter computer at the site of the IfR-station. Alarm levels are low in order to have an early warning against airborne radioactivity. New techniques for remote maintenance of the measuring devices and nuclide identification are being planned and tested.
Automatic calculation of sites for positioning of mobile gamma probes in case of an emergency at a Bavarian nuclear power plant
Authors: Faleschini J. , Falk H. , Gölling K. 
Published: December 2013

Abstract
In the early phase of a nuclear emergency many decisions have to be made by the authorities. So it is of great support when certain measures run automatically. Additional mobile gamma probes are therefore picked up by the local fire brigade at the nuclear power plant without further ado by the authorities. The gamma probes are then positioned at sites which are calculated automatically, taking into account the momentary weather situation. The sites are printed on a map handed over to the firemen. A location of a standby area after having set up the gamma probes is also given on this map.