Validation of DRAGON5 Lattice Code for PWR (Pressurized Water Reactor) Applications Using Depletion Benchmarks by Detailed Comparison with SERPENT2 Monte Carlo Code

L’objectif de ce projet est de valider un schéma de calcul à deux niveaux pour quatre benchmarks d’assemblage de réacteurs à eau sous pression (REP) avec le code de réseau DRAGON5. Ici, nous validons le schéma à deux niveaux par rapport à un schéma classique à un niveau du calcul DRAGON5 et le comparons avec les résultats du code Monte-Carlo SERPENT2 à trois burnups différents. Les résultats sont comparés à 0 burnup, au burnup à maximum et au burnup maximum de 70 GWd/t. De plus, trois benchmarks de cellules uniques PWR sont validés en comparant les résultats du schéma à un niveau DRAGON5 avec ceux du code Monte-Carlo SERPENT2. Le schéma classique à un niveau utilise généralement la méthode des probabilités de collision (CP) pour les calculs de cellules uniques et la méthode des caractéristiques (MOC) pour les calculs d’assemblage. Les calculs MOC sont capables de traiter des problèmes plus complexes et de fournir une meilleure précision au prix d’un plus grand coût de calcul. Un schéma à deux niveaux a été proposé pour traiter les assemblages PWR. Au premier niveau, la méthode à courant d’interface (IC) est utilisée sur un maillage d’énergie à 295 groupes pour effectuer un calcul de flux efficace. Tous les schémas de calcul utilisent un calcul d’autoprotection basé sur la méthode des sous-groupes avec des tables de probabilités mathématiques avec une technique de solution IC. Le premier niveau est suivi par une correction de Super Homogénéisation (SPH). Ensuite, au deuxième niveau, la méthode MOC utilise l’estimation initiale du flux pour effectuer un calcul de flux plus détaillé sur le maillage énergétique de 26 groupes. Dans cette étude, nous montrons que le schéma optimisé à deux niveaux est capable d’effectuer un calcul d’assemblage PWR plus rapidement sans perte significative de précision de calcul.----------Abstract The goal of this project is to validate a two-level calculation scheme of four Pressurized Water Reactor (PWR) assembly benchmarks with the DRAGON5 lattice code. Here, we validate the two-level scheme with classical one-level scheme of DRAGON5 calculation and compare it with the results of SERPENT2 Monte Carlo code at three di˙erent burnups. The results are compared at 0 burnup, burnup at maximum and at maximum burnup of 70 GWd/t. Additionally, three PWR pin cell benchmarks are validated by comparing DRAGON5 one-level scheme results with those of SERPENT2 Monte Carlo code. The classical one-level scheme typically uses Collision Probability (CP) method for pin cell calculations and Method of Characteristics (MOC) for assembly calculations. MOC calcula-tions are capable of handling larger problems and provide better accuracy at the expense of being computationally more intensive. A two-level scheme was proposed for PWR assemblies. At the first level, Interface Current (IC) method is used on 295-group energy mesh to perform eÿcient flux calculation. All computational schemes use subgroup self-shielding with mathematical probability tables and IC solution technique. The first level is followed by Super Homogenisation (SPH) correction. Then, at the second level, MOC method uses initial estimate of the flux to perform a more detailed flux calculation on the 26-group energy mesh. In this study, we show that the optimized two-level scheme is capable of performing a PWR assembly calculation essentially faster without any significant loss of calculation precision

Osteometric data of Avian Fauna of Armenia: A baseline for zoologists and archaeozoologists

Modern bird skeletons stored in the faunal collections of the Institute of Zoology of the Scientific Center of Zoology and Hydroecology NAS Armenia constitute a source material for this dataset. The osteological material in the scientific collections has been accumulated in the course of faunal studies in Armenia over the span of 60 years. The osteometric dataset sheds light on the country's species diversity and includes cranial and postcranial measurements (carpometacarpus, humerus, tibia, femur, tarsometatarsus, radius and ulna) of 141 bird skeletons which belong to 81 bird species, 34 families and 17 orders.Bird skeletons have been collected by means of specimen collection from the wild for scientific study prior to 1990s when the practice was common and recovered opportunistically after 1990s from birds found dead through natural causes and incidents.Recent bird skeletons (bones) serve as a unique comparative resource for zoological research and for identifying bird bones recovered from archaeological and natural deposits

Role of Fibrinogen in Trauma-Induced Coagulopathy

Fibrinogen is the first coagulation factor to decrease after massive hemorrhage. European massive transfusion guidelines recommend early repletion of fibrinogen; however, this practice has not been widely adopted in the US. We hypothesize that hypofibrinogenemia is common at hospital arrival and is an integral component of trauma-induced coagulopathy. This study entailed review of a prospective observational database of adults meeting the highest-level activation criteria at an urban level 1 trauma center from 2014 through 2020. Resuscitation was initiated with 2:1 red blood cell (RBC) to fresh frozen plasma (FFP) ratios and continued subsequently with goal-directed thrombelastography. Hypofibrinogenemia was defined as fibrinogen below 150 mg/dL. Massive transfusion (MT) was defined as more than 10 units RBC or death after receiving at least 1 unit RBC over the first 6 hours of admission. Of 476 trauma activation patients, 70 (15%) were hypofibrinogenemic on admission, median age was 34 years, 78% were male, median New Injury Severity Score (NISS) was 25, and 72 patients died (15%). Admission fibrinogen level was an independent risk factor for MT (odds ratio [OR] 0.991, 95% CI 0.987-0.996]. After controlling for confounders, NISS (OR 1.034, 95% CI 1.017-1.052), systolic blood pressure (OR 0.991, 95% CI 0.983-0.998), thrombelastography angle (OR 0.925, 95% CI 0.896-0.954), and hyperfibrinolysis (OR 2.530, 95% CI 1.160-5.517) were associated with hypofibrinogenemia. Early cryoprecipitate administration resulted in the fastest correction of hypofibrinogenemia. Hypofibrinogenemia is common after severe injury and predicts MT. Cryoprecipitate transfusion results in the most expeditious correction. Earlier administration of cryoprecipitate should be considered in MT protocols

Traumatic brain injury provokes low fibrinolytic activity in severely injured patients

BACKGROUNDTraumatic brain injury (TBI) in combination with shock has been associated with hypocoagulability. However, recent data suggest that TBI itself can promote a systemic procoagulant state via the release of brain-derived extracellular vesicles. The objective of our study was to identify if TBI was associated with differences in thrombelastography indices when controlling for other variables associated with coagulopathy following trauma. We hypothesized that TBI is independently associated with a less coagulopathic state. METHODSProspective study includes all highest-level trauma activations at an urban Level I trauma center, from 2014 to 2020. Traumatic brain injury was defined as Abbreviated Injury Scale head score greater than 3. Blood samples were drawn at emergency department admission. Linear regression was used to assess the role of independent predictors on trauma induced coagulopathy. Models adjusted for Injury Severity Score (ISS), shock (defined as ED SBP108, or first hospital base deficit >10), and prehospital Glasgow Coma Scale score. RESULTSOf the 1,023 patients included, 291 (28%) suffered a TBI. Traumatic brain injury patients more often were female (26% vs. 19%, p = 0.01), had blunt trauma (83% vs. 43%, p < 0.0001), shock (33% vs. 25%, p = 0.009), and higher median ISS (29 vs. 10, p < 0.0001). Fibrinolysis shutdown (25% vs. 18%) was more common in the TBI group (p < 0.0001). When controlled for the confounding effects of ISS and shock, the presence of TBI independently decreases lysis at 30 minutes (LY30) (beta estimate: -0.16 ± 0.06, p = 0.004). This effect of TBI on LY30 persisted when controlling for sex and mechanism of injury in addition to ISS and shock (beta estimate: -0.13 ± 0.06, p = 0.022). CONCLUSIONTraumatic brain injury is associated with lower LY30 independent of shock, tissue injury, sex, and mechanism of injury. These findings suggest a propensity toward a hypercoagulable state in patients with TBI, possibly due to fibrinolysis shutdown. LEVEL OF EVIDENCEPrognostic and Epidemiologic; Level III

Goal-directed Hemostatic Resuscitation of Trauma-induced Coagulopathy

BackgroundMassive transfusion protocols (MTPs) have become standard of care in the management of bleeding injured patients, yet strategies to guide them vary widely. We conducted a pragmatic, randomized clinical trial (RCT) to test the hypothesis that an MTP goal directed by the viscoelastic assay thrombelastography (TEG) improves survival compared with an MTP guided by conventional coagulation assays (CCA).MethodsThis RCT enrolled injured patients from an academic level-1 trauma center meeting criteria for MTP activation. Upon MTP activation, patients were randomized to be managed either by an MTP goal directed by TEG or by CCA (ie, international normalized ratio, fibrinogen, platelet count). Primary outcome was 28-day survival.ResultsOne hundred eleven patients were included in an intent-to-treat analysis (TEG = 56, CCA = 55). Survival in the TEG group was significantly higher than the CCA group (log-rank P = 0.032, Wilcoxon P = 0.027); 20 deaths in the CCA group (36.4%) compared with 11 in the TEG group (19.6%) (P = 0.049). Most deaths occurred within the first 6 hours from arrival (21.8% CCA group vs 7.1% TEG group) (P = 0.032). CCA patients required similar number of red blood cell units as the TEG patients [CCA: 5.0 (2-11), TEG: 4.5 (2-8)] (P = 0.317), but more plasma units [CCA: 2.0 (0-4), TEG: 0.0 (0-3)] (P = 0.022), and more platelets units [CCA: 0.0 (0-1), TEG: 0.0 (0-0)] (P = 0.041) in the first 2 hours of resuscitation.ConclusionsUtilization of a goal-directed, TEG-guided MTP to resuscitate severely injured patients improves survival compared with an MTP guided by CCA and utilizes less plasma and platelet transfusions during the early phase of resuscitation