Untersuchungen an Katalysatoren zur Reduktion von Stickoxiden und Sauerstoff mit Wasserstoff

During the dissolution of nuclear fuel in nitric acid nitric oxides are formed, which are released into the off-gas together with the gaseous fission products. The main component of dissolver off-gas is water saturated air. Before the removal of the fission noble gases xenon and krypton in a cryogenic separation unit, pretreatment steps are necessary, one of which is the removal of oxygen and nitric oxides by reaction with hydrogen. The goal of the work described herein was to find a catalyst suitable for the reduction of oxygen and nitric oxides with hydrogen. lt is destred to have a residual concentration of oxygen and nitric oxide < 1 ppm and at the same time to suppress the reactton Zeading to the formation of ammonia. Three catalysts (one noble metal, one nicket and one ruthentum catalyst) have been tested at various temperatures and space velocities. All three catalysts removed oxygen and nitric oxides to below 1 ppm, but only the ruthenium catalyst suppressed the formation of ammonia

Kosten des Verbrennungs-HEAD END's einschließlich der Kr-Abtrennungbei der Wiederaufarbeitung von HTR-Brennelementen

Es werden die C-Verbrennung und die Kr-Abtrennung während des Verbrennungs-HEAD ENDs der Wiederaufarbeitung von HTR-Brennelementen beschrieben. Die Kosten für Bau und Betrieb eines Verbrennungs-HEAD ENDs der Wiederaufarbeitungskapazitäten von 5000 bis 50000 MWe-HTR-Leistung wurden ermittelt. Die Kostenschätzungen gliedern sich in Investitions- und Betriebskosten, ferner nach dem Anteil des N$_{2}$-Gehalts im Verbrennungsabgas, der stark kostenbeeinflussend wirkt. Es zeigt sich, daß für den Fall der Kr-Abtrennung aus dem Verbrennungsabgas sowohl die Investitionskosten als auch die Betriebskosten des HEAD ENDs für N$_{2}$-haltiges Abgas wesentlich über denjenigen des N$_{2}$losen liegen. Die C-Verbrennung des Graphits der HTR-Brennelemente sollte deswegen nur mit N$_{2}$-freiem Anströmgas durchgeführt werden

Evaluation of mass balance investigations in coal fired power plants

Coal contains trace quantities of many elements that can be toxic if present in high enough concentrations. Many of these elements are released after combustion into more available forms for human assimilation. Hence, burninq coal increases the potential for toxic trace element hazard. Assessment of the literature an measurements of trace elements during the combustion of coal has made it clear that these measurements are imprecise and contradictory. In this literature review, mass balance of measurements in coal-fired plants are evaluated and research in the enrichment of trace elements in coal ashes is reviewed. The problems in measuring trace elements in coal-fired facilities are presented with the intention that the knowledge of the difficulties outlined here will promote future study and active research in these areas