Post-BEMUSE Reflood Model input uncertainty methods (PREMIUM) Benchmark Phase II: identification of influential Parameters

The objective of the Post-BEMUSE Reflood Model Input Uncertainty Methods (PREMIUM) benchmark is to progress on the issue of the quantification of the uncertainty of the physical models in system thermal-hydraulic codes by considering a concrete case: the physical models involved in the prediction of core reflooding. The PREMIUM benchmark consists of five phases: - Phase I: mainly, definition of the different uncertainty methods; - Phase II: determination of the physical models influential in reflooding using the test 216 of the FEBA programme; - Phase III: quantification of the uncertainties of the parameters associated with the physical models identified as influential within Phase II, using FEBA/SEFLEX experimental results; - Phase IV: validation of the found uncertainties within Phase III by propagating them in the 2-D PERICLES reflood experiment; this phase will be performed blindly except for the coordinators; - Phase V: synthesis report. This report presents the results of Phase II. Phase II is dedicated to the identification of the uncertain code parameters associated with physical models used in the simulation of reflooding conditions. This identification is made on the basis of the Test 216 of the FEBA/SEFLEX programme according to the following steps: - identification of influential phenomena; - identification of the associated physical models and parameters, depending on the used code; - quantification of the variation range of identified input parameters through a series of sensitivity calculations. A procedure for the identification of potentially influential code input parameters has been set up in the Specifications of Phase II of PREMIUM benchmark. A set of quantitative criteria has been as well proposed for the identification of influential IP and their respective variation range. Thirteen participating organisations, using 8 different codes (7 system thermal-hydraulic codes and 1 sub-channel module of a system thermal-hydraulic code) submitted Phase II results. The base case calculations show spread in predicted cladding temperatures and quench front propagation that has been characterized. All the participants, except one, predict a too fast quench front progression. Besides, the cladding temperature time trends obtained by almost all the participants show oscillatory behaviour which may have numeric origins. Adopted criteria for identification of influential input parameters differ between the participants: some organisations used the set of criteria proposed in Specifications “as is”, some modified the quantitative thresholds proposed in Specifications, and others used their own methodologies. This fact was a partial reason for the different ranges of input parameter variation identified by participants, in addition to differences of the physical models adopted by the different codes. Therefore, such different variation ranges of IP and, correspondingly, such different variation ranges of cladding temperature and time of rewet, make rather difficult the task of meaningful and easy-comprehendible comparison of Phase II results. Out of a total of 72 input parameters, initially considered by all participants, only 6 were identified as influential by more than 4 participants that are: - bundle power; - wall heat transfer coefficient; - interphase friction coefficient; - interphase heat transfer coefficient; - heat transfer (enhancement) at the quench front; - droplet diameter. It should be noted that actual parameters considered in parameter “Heat transfer (enhancement) at the quench front” are code-specific and may have different influence on calculation results. Several participants discarded some identified influential parameters (e.g., droplet diameter) due to existing relation between this kind of parameters so-called “Input Coefficient Parameters” and more global parameters (e.g. interfacial friction coefficient and interphase heat transfer coefficient which use the droplet diameter) so-called “Input Global Parameters”. Some participants also discarded identified influential so-called “Input Basic Coefficients” (e.g. bundle power) since their uncertainty has not to be determined in the Phase III but will be provided by the coordinator from experimental data. The behaviour of the variation of the responses at the extremes of IP range of variation greatly depends on the type of input parameter and on the code used. Mainly, the following two different behaviours can be characterized: - For some parameters, like power, wall heat transfer and interphase heat transfer coefficients, a qualitative (but not quantitative) agreement between different codes is observed. - For other parameters, like interphase friction coefficient and droplet diameter, a contrary behaviour (i.e. in correspondence of one of the extreme of the IP range, the direction of change of the responses is different) between different codes and even between different selected models within the same code can be observed. This suggests that the effect of such parameters on the cladding temperatures is quite complex, probably because it involves a lot of physical models (e.g., via interphase friction and interphase heat transfer coefficients for the droplet diameter). It shall be noted that the analysis of differences between the reflood models of different codes is out of scope of the PREMIUM benchmark. Nevertheless, it is recommended to take into account the physical models/ input parameters found as influential by the other participants in order to select the influential input parameters for which uncertainties are to be quantified within the Phase III of PREMIUM. In particular, input parameters identified as influential by other participants using the same code should be considered

An Integrated Software Platform for Best Estimate Safety Analyses of Nuclear Power Plants

Nuclear power plant safety is granted through the demonstration that regulatory acceptance criteria are fulfilled by the provided (calculated) analyses of the NPP performances and sufficient safety margins are respected during normal operation, anticipated transients and postulated accident conditions. Safety margins are very hard to determine in absolute terms, numerical calculations are used to assess their values. Over the last 30 years an extensive effort has been carried out aiming to improve the knowledge of the nuclear power plant behaviour under transient scenarios. The development of Best Estimate (BE) computer codes are the direct consequence of these noteworthy efforts. The availability of more sophisticated and specialized computer codes gives the analyst the possibility to perform very detailed analysis in all the fields involved in the safety of a NPP: thermal-hydraulics, CFD, 3D neutron kinetics etc. The possibility to create a software environment where a multidisciplinary problem can be solved adopting different specialized codes able to exchange data among them is a fruitful approach to the problem aiming to improve the results. The computational tools, adopted in best-estimate approach in licensing, include a) the best estimate computer codes; b) the nodalizations together with the procedures for the development and the qualification; c) the uncertainty methodology. The Nuclear Research Group of San Piero a Grado of the University of Pisa has developed a software platform with 15 interacting computer codes. Such platform covers the reactor simulation multidisciplinary problem from generation of neutron cross-sections, through system thermal-hydraulic analyses, up to detailed structural and fuel mechanics studies and it embeds software procedures for automatized data transfer between codes. Together with methodological procedures for nodalizations development and qualification the platform leads to a great decrease of the human induced error in the results. The developed platform has been tested and successfully applied to perform the safety analyses required by the Chapter 15 of the Final Safety Analysis Report of the CNA-2 nuclear power plant in Argentina

Recent Applications of RELAP5-3D at GRNSPG

CNA2 : FSAR activities Standard Consolidated Reference Experimental Database MASLWR benchmark OECD benchmarks CHF calculation in low mass flux condition Turbulence effects in Relap5-3

Observation of the second harmonic in superconducting current-phase relation of Nb/Au/(001)YBa2Cu3Ox heterojunctions

The superconducting current-phase relation (CPR) of Nb/Au/(001)YBa2Cu3Ox heterojunctions prepared on epitaxial c-axis oriented YBa2Cu3Ox thin films has been measured in a single-junction interferometer. For the first time, the second harmonic of the CPR of such junctions has been observed. The appearance of the second harmonic and the relative sign of the first and second harmonics of the CPR can be explained assuming, that the macroscopic pairing symmetry of our YBa2Cu3Ox thin films is of the d+s typeComment: 11 pages, 4 figure

LATERAL TEETH DISTOVERSION AT THE REMOVABLE ORTHODONTIC APPLIANCE

The shortening of a tooth arch is clinically shown by crowding. In the final period of a mixed bite, the place disadvantage for canines is often detected. The problem of elongation of a tooth arch due to distal movement of premolars, the first and second permanent molars on removable appliances is discussed. In practical orthodontia, this way of treatment of the shortened tooth arch traditionally solved only with use of the fixed equipment. The fixed equipment allows to control the made effort to each of the moved teeth. Power source in removable appliances are screws. When designing removable orthodontic appliances the area of the moved teeth and a possibility of force action of the used orthodontic screws on the moved group of teeth is considered. Maintenance of balance between the applied force and the area of roots of the moved teeth allows to reach optimization of process of reorganization of parodentium. The clinical case showing efficiency of removable appliances in a constant occlusion for elongation of a tooth arch is presented, their design is described

Clinical and roentgenological aspects of diagnosis and treatment of temporomandibular joint pathology

The article presents the occurrence of temporomandibular joint pathology (20,9 %) in children of prepubertal age. It was revealed that habitual dislocation that appears on the background of asymmetric occlusion with close position of teeth in frontal and lateral areas of dentition is typical for this age group. It was determined that clinical signs of TM] pathology in children and adults are different: pain syndrome and noise effect at the lower jaw movements are not typical for children in contrast to the adults. According to the data of outpatient's cards the structure of nosologic forms of pathology during different periods of occlusion formation is defined. It was determined that TM] pathology begins to form in preschool age and later on its frequency increases. The analysis of morbidity by sex showed that women have TM] pathology more often and also they have age tendency to the aggravation of the pathology that develops in future in appearance of dislocations of intraarticular disks. The article suggests the differentiated approach tactics for the treatment of TM] diseases that was rather effective

ON THE DIAGNOSTICS OF SAGITTAL OCCLUSION ANOMALIES

In the known classifications, there is no terminological wording as asymmetrical sagittal occlusion of segments of dentition in lateral areas. The work complemented classification of sagittal occlusion anomalies in the lateral areas of dentition of following types of asymmetric occlusion: Type I of asymmetrical sagittal occlusion: correct (neutral - class 1] ratio of lateral teeth on one side and distal (class 2) ratio on the other side. Type II of asymmetrical sagittal occlusion: correct (neutral - class 1] ratio of lateral teeth on one side and mesial (class 3) ratio on the other side. Type III of asymmetrical sagittal occlusion: distal (class 2] ratio of lateral teeth on one side and mesial (class 3) ratio on the other side. Type of asymmetrical sagittal occlusion is not the basis for the establishment of gravity anomalies

Changing the color of tooth enamel in the process of orthodontic treatment

Teeth discoloration is a rare orthodontic complication during orthodontic treatment. We present 6-year clinical observation conducted from January 2010 till December 2016. The eighteen orthodontic patients with teeth discoloration took part in this observation. Four patients were excluded from the observation as their teeth discoloration were under orthodontic treatment. During clinical observation period, discovered discoloration was evaluated as «improved» in 4 out of 14 teeth (28.5 %), as «maintained» in 10 teeth (71.4 %). Electroodontodiagnosis conducted during the initial detection period of discoloration showed 14.3 % positivity, which improved to 21.4 % at the final follow-up. The radiological pictures of the teeth showed no abnormalities. Thus, we can assume that teeth with one wide long root canal are more prone to damage to the pulp blood supply. Discoloration is also more frequent in the maxillary teeth, possibly due to the overjet relationship, which may increase susceptibility to trauma in the maxillary teeth. We should keep dynamical observation in the orthodontic practice as teeth color could reverse to the initial without additional interference. 1f discoloration does not improve even after sufficient observation, it is necessary to start orthodontic treatment (endodontic, prosthetic) or bleaching. A patient should be informed that discoloration does not always indicate devitalization or pulp necrosis. Instead of "devitalization" or "pulp necrosis" we recommend to use the term "discoloration"

Blocking the CD47-SIRPα interaction reverses the disease phenotype in a polycythemia vera mouse model

Polycythemia vera (PV) is a hematopoietic stem cell neoplasm driven by somatic mutations in JAK2, leading to increased red blood cell (RBC) production uncoupled from mechanisms that regulate physiological erythropoiesis. At steady-state, bone marrow macrophages promote erythroid maturation, whereas splenic macrophages phagocytose aged or damaged RBCs. The binding of the anti-phagocytic ("don't eat me") CD47 ligand expressed on RBCs to the SIRPα receptor on macrophages inhibits phagocytic activity protecting RBCs from phagocytosis. In this study, we explore the role of the CD47-SIRPα interaction on the PV RBC life cycle. Our results show that blocking CD47-SIRPα in a PV mouse model due to either anti-CD47 treatment or loss of the inhibitory SIRPα-signal corrects the polycythemia phenotype. Anti-CD47 treatment marginally impacted PV RBC production while not influencing erythroid maturation. However, upon anti-CD47 treatment, high-parametric single-cell cytometry identified an increase of MerTK+ splenic monocyte-derived effector cells, which differentiate from Ly6C$^{hi}$ monocytes during inflammatory conditions, acquire an inflammatory phagocytic state. Furthermore, in vitro, functional assays showed that splenic JAK2 mutant macrophages were more "pro-phagocytic," suggesting that PV RBCs exploit the CD47-SIRPα interaction to escape innate immune attacks by clonal JAK2 mutant macrophages