Beryllides as advanced materials for neutron multiplication

The neutron multiplier is an essential component of the blanket of future thermonuclear reactors, which should provide the tritium breeder with a sufficient amount of neutrons of a certain energy. Among all chemical elements, only beryllium and lead have an advantageous ratio of high neutron multiplication reaction at low neutron absorption rates. However, pure metals – beryllium and lead – for various reasons cannot be used in the harsh operating conditions of a fusion reactor blanket. Intermetallic compounds of beryllium – beryllides have a number of advantages over pure beryllium and are currently considered to be the reference neutron multiplication material for the Helium Cooled Pebble Bed (HCPB) breeding blanket concept of EU DEMO fusion reactor. Recently, a batch of full-size beryllide blocks has been manufactured on an industrial scale in cooperation with the Ulba Metallurgical Plant. The present work is devoted to the characterization and analysis of these beryllide blocks so that the material could be used for the manufacture of a blanket. Titanium beryllide (TiBe12) blocks are hexagonal prisms with an internal hole, while chromium beryllide (CrBe12) blocks are solid prisms of complex shape. The resulting blocks have a single-phase structure of the corresponding beryllide with a small impurity in the form of beryllium oxide. One of the titanium beryllide blocks also has about 7% residual beryllium phase. Grains of titanium beryllide have an average size of about 7–8 μm, while grains of chromium beryllide are much larger and reach 40–50 μm. Mechanical compression and bending tests of beryllides showed their very high strength, which is maintained up to 1000°C. In terms of specific compressive strength, the single-phase TiBe12 surpasses all materials, except diamond, in the 700–1000°C temperature range. Chromium beryllide and titanium beryllide with 7% of the beryllium phase have lower strength, but higher ductility. Corrosion tests were carried out in air and in He + 2% water vapor at 800–1200°C. Beryllides have high corrosion resistance similar to Ni-base superalloys and high temperature ceramics. Long-term thermal cycling tests with rapid heating and cooling, simulating operation in a fusion reactor, showed high resistance of beryllides to thermal shocks. The results obtainedare also discussed from the point of view of the application of beryllides in other areas

Tritium and helium release from beryllium pebbles neutron-irradiated up to 230appm tritium and 3000appm helium

Study of tritium and helium release from beryllium pebbles with diameters of 0.5 and 1 mm after high- dose neutron irradiation at temperatures of 6 86–96 8 K was performed. The release rate always has a single peak, and the peak temperatures at heating rates of 0.017 K/s and 0.117 K/s lie in the range of 1100–1350 K for both tritium and helium release. The total tritium release from 1 mm pebbles decreases considerably by increasing the irradiation temperature. The total tritium release from 0.5 mm pebbles is less than that from 1 mm pebbles and remains constant regardless of the irradiation temperature. At high irradiation temperatures, open channels are formed which contribute to the enhanced tritium release

Next to leading order eta production at hadron colliders

Inclusive eta production at hadron colliders is considered,based on evaluation of eta fragmentation functions at next to leading order. Absolute predictions at LHC and SSC are presented, including the ratio $\eta/\pi^0$, together with the estimate of the theoretical uncertainty, as a possible neutral background to the $H\to \gamma\gamma$ detection.Comment: 8 pages, latex, FNT/T-93/13,14 figures avilable upon reques

Irradiation programme HFR phase IIb - SPICE. Impact testing on up to 16.3 dpa irradiated RAFM steels. Final report for task TW2-TTMS 001b-D05

Bestrahlungsprogramm HFR Phase IIb – SPICE: Kerbschlagbiegeuntersuchungen an bis 16.3 dpa bestrahlten RAFM Stählen Die Untersuchung des bestrahlungsinduzierten Versprödungsverhaltens von niedrigaktivierbaren ferritisch-martensitischen (RAFM) Stählen bildet das Ziel der vorliegenden Arbeit. Die Neutronenbestrahlung bei verschiedenen Bestrahlungstemperaturen (250-450 °C) bis zu einer Schädigung von 16,3 dpa (nominell) wurde im Hoch Fluss Reaktor („High Flux Reactor“) Petten im Rahmen des HFR Phase IIb (SPICE) Bestrahlungsprogramms durchgeführt. Die Kerbschlageigenschaften wurden an miniaturisierten Charpy-V Proben (des KLST Typs) mittels der instrumentierten Kerbschlagbiegeversuche ermittelt. Der Hauptschwerpunkt des Bestrahlungsprogramms liegt in der Untersuchung des Einflusses der Neutronenbestrahlung auf die mechanischen Eigenschaften von einem europäischen RAFM Referenzstahl für die Erste Wand des Demonstrationsreaktors (DEMO), EUROFER97, bei zwei verschiedenen Wärmebehandlungen. Die mechanischen Eigenschaften von EUROFER97 wurden mit denen von internationalen Referenzmaterialien (F82H-mod, OPTIFER-Ia, GA3X und MANET-I), welche im SPICE Projekt untersucht wurden, verglichen. Die Bestrahlungsresistenz von bis 16,3 dpa bei 250-450 °C bestrahltem EUROFER97 ist vergleichbar mit der von besten Referenz-Strukturmaterialien. Es wurde für alle untersuchten RAFM Stähle eine erhebliche Tieftemperaturversprödung (Tirr ≤ 300 °C) beobachtet. Die Wärmebehandlung von EUROFER97 bei höherer Austenisierungstemperatur führt zur wesentlichen Verbesserung des Versprödungsverhaltens bei niedrigen Bestrahlungstemperaturen (Tirr ≤ 350 °C). Bei Tirr ≥ 350 °C liegen die Sprödbruchübergangstemperaturen (DBTT) von untersuchten niedrigaktivierbaren Stählen unterhalb von -20 °C und damit weit unterhalb der Anwendungstemperatur. Die Analyse des Verfestigungs- vs. Versprödungs- Verhaltens deutet auf die verfestigungsdominierte Versprödung unterhalb von Tirr ≤ 350 °C mit 0,17≤ C100 ≤ 0,53 °C/MPa. Oxiddispersionsgehärteter ODS EUROFER Stahl mit 0,5 wt.% Y2O3 wurde bei ausgewählten Temperaturen bestrahlt. Bereits im unbestrahlten Zustand zeigte ODS EUROFER keine be- friedigende Kerbschlagbiegeeigenschaften, gekennzeichnet durch eine niedrige USE = 2,54 J und durch eine große DBTT = 135 °C. Die Zunahme von USE für Bestrahlungstemperaturen unterhalb von Tirr ≤ 350°C deutet außerdem auf ein nicht optimiertes Herstellungsverfahren. Bei Tirr = 250 °C ist die bestrahlungsinduzierte Verschiebung der Übergangstemperatur vergleichbar mit der vom EUROFER97. Bei höheren Bestrahlungstemperaturen zeigt hingegen ODS EUROFER größere Versprödung im Vergleich zum Referenzmetall. Die Rolle des Heliums in der Materialversprödung wurde an EUROFER97 basierten Stählen untersucht, welche mit verschiedenem Bor Gehalt (0,008-0,112 wt.%) dotiert wurden. Bor dotierte Proben zeigen zunehmende Versprödung und Abnahme der Zähigkeit mit der Zunahme des generierten Helium Gehalts. Bis zu einem Helium Gehalt von 84 appm ist bei Tirr = 250 °C Helium induzierte Versprödung auf Helium induzierte Verfestigung zurückzuführen. Höhere Helium Konzentrationen führten zu weiteren Versprödungsmechanismen zusätzlich zur Helium induzierten Verfestigung

New insights into microstructure of irradiated beryllium based on experiments and computer simulations

The microstructural response of beryllium after neutron irradiation at various temperatures (643–923 K) was systematically studied using analytical transmission electron microscope that together with outcomes from advanced atomistic modelling provides new insights in the mechanisms of microstructural changes in this material. The most prominent feature of microstructural modification is the formation of gas bubbles, which is revealed at all studied irradiation temperatures. Except for the lowest irradiation temperature, gas bubbles have the shape of thin hexagonal prisms with average height and diameter increasing with temperature. A high number density of small bubbles is observed within grains, while significantly larger bubbles are formed along high-angle grain boundaries (GB). Denuded zones (DZ) nearly free from bubbles are found along both high- and low-angle grain boundaries. Precipitations of secondary phases (mainly intermetallic Al-Fe-Be) were observed inside grains, along dislocation lines and at GBs. EDX analysis has revealed homogeneous segregation of chromium and iron along GBs. The observed features are discussed with respect to the available atomistic modelling results. In particular, we present a plausible reasoning for the abundant formation of gas bubbles on intermetallic precipitates, observation of various thickness of zones denuded in gas bubbles and precipitates, and their relation to the atomic scale diffusion mechanisms of solute-vacancy clusters

Assessing social and economic impact of subcutaneous mAbs in oncology

Background: Rituximab and trastuzumab were the first monoclonal antibodies (mAbs) approved for the treatment of cancer patients. Both antibodies are administered intravenously (EV), but subcutaneous (SC) formulations have recently been developed. SC formulations proved to be as safe and effective as EV and to offer substantial benefits to the patient. Objective: The aim of this study was to provide a multidimensional assessment of the impact of rituximab and trastuzumab SC compared to the EV formulation, providing a particular focus on expected social and economic benefits for the patient. Methods: The best established HTA methods were applied to gather and organize evidence concerning the clinical, economic, organizational, social and ethical impact of SC formulations of rituximab and trastuzumab. Social aspects were investigated applying regression methods to data collected with a previous research, while the potential savings associated with the use of SC formulations were estimated by a simple economic model applying the societal perspective. Results Patients undergoing subcutaneous formulation are significantly more satisfied with their treatment experience than those treated with intravenous formulation. Subcutaneous formulation reduces patient dosing times, with a positive effect on the care provider's autonomy and productivity. Potential savings associated with the use of rituximab SC were estimated in € 4,050 per patient per year on average. For trastuzumab SC the estimated potential savings amounted to € 3,400 per patient per year, on average. Conclusion Rituximab and trastuzumab are promising treatment options significantly improving patients qol and reducing the treatment burden in terms of societal costs

Index matching between passive and active tellurite glasses for use in microstructured fiber lasers: Erbium doped lanthanum-tellurite glass

Active and passive variants of La-containing tellurite glasses have been developed with matched refractive indices. The consequences of adding lanthanum to the glass was studied through measurements of the crystallization stability, glass viscosity and the loss of unstructured fibers. Doping the glass with erbium allowed for any spectroscopic changes to be observed through measurements of the absorption and energy level lifetimes. The fluorescence emission spectra were measured at 1.5 microm and, to the best of our knowledge, for the first time in tellurite glass at 2.7 microm.Michael R. Oermann, Heike Ebendorff-Heidepriem, Yahua Li, Tze-Cheung Foo, and Tanya M. Monrohttp://www.opticsinfobase.org/abstract.cfm?URI=oe-17-18-1557

Rhomboid family member 2 regulates cytoskeletal stress-associated Keratin 16.

Keratin 16 (K16) is a cytoskeletal scaffolding protein highly expressed at pressure-bearing sites of the mammalian footpad. It can be induced in hyperproliferative states such as wound healing, inflammation and cancer. Here we show that the inactive rhomboid protease RHBDF2 (iRHOM2) regulates thickening of the footpad epidermis through its interaction with K16. K16 expression is absent in the thinned footpads of irhom2-/- mice compared with irhom2+/+mice, due to reduced keratinocyte proliferation. Gain-of-function mutations in iRHOM2 underlie Tylosis with oesophageal cancer (TOC), characterized by palmoplantar thickening, upregulate K16 with robust downregulation of its type II keratin binding partner, K6. By orchestrating the remodelling and turnover of K16, and uncoupling it from K6, iRHOM2 regulates the epithelial response to physical stress. These findings contribute to our understanding of the molecular mechanisms underlying hyperproliferation of the palmoplantar epidermis in both physiological and disease states, and how this 'stress' keratin is regulated

Trimester-specific reference intervals for thyroid function parameters in pregnant Caucasian women using Roche platforms: a prospective study

Background: Standard thyroid function parameters reference intervals (RI) are unsuitable during pregnancy, potentially resulting in incongruous treatments that may cause adverse effects on pregnancy outcomes. We aimed at defining trimester-specific TSH, FT4 and FT3 RI, using samples longitudinally collected from healthy Caucasian women. Materials and methods: Blood samples from 150 healthy Caucasian women, who had a physiological gestation and a healthy newborn at term, were collected in each trimester and at around six months post-partum. They showed mild iodine deficiency. After excluding women with overt TSH abnormalities (> 10 mU/L) and/or TPO antibodies, data from 139 pregnant women were analyzed by means of widely used Roche platforms, and TSH, FT4 and FT3 trimester-specific RI were calculated. Post-partum data were available for 55 subjects. Results: Serum TSH RI were 0.34-3.81 mU/L in the first trimester, and changed slightly to 0.68-4.07 U/L and 0.63-4.00 mU/L in the second and third trimester, respectively. Conversely, both FT4 and FT3 concentrations progressively decreased during pregnancy, the median values in the third trimester being 14.8% and 13.2% lower, respectively, than in the first trimester. Thyroid function parameters in the first trimester were similar to those measured after the end of pregnancy. Conclusions: This study calculates trimester-specific RI for thyroid function parameters in pregnancy, and proposes the reference limits that should be adopted when using Roche platforms in Caucasian women