Impact of hygrothermal aging on gas release behavior and multi-stage pyrolysis kinetics of biomass: Insights from TG-FTIR and DAEM analysis

In recent years, with increasing of a demand of alloyed steel powder, knowledge of gas release behavior has been required to improve the quality of the produced material. In this paper, the gas release behavior from Fe powder, Fe-Cr powder, Fe-Ni powder, and Fe-Cr-Ni powder during heating in pure He gas were investigated by a gas chromatography analyzer. CO2, H2O, and C3H8 gases were detected from the powders. Especially, in Fe powder and Fe-Ni powder, CO2 gas was remarkably released over 600°C. H2O gas generation was detected from Fe-Ni powder and Fe-Cr-Ni powder in temperature range of 200-600°C. The amount of CO2 gas in Fe powder and Fe-Ni powder was clearly higher than that in Fe-Cr powder and Fe-Cr-Ni powder. Additionally, the amount of H2O gas in Fe-Ni powder and Fe-Cr-Ni powder was also higher than that in Fe powder and Fe-Cr powder. Precisely, it was guessed that CO2 gas release behavior depended on the Cr component in the alloyed steel powder, and that H2O gas release behavior rerated with Ni component. As comparative experiments, the gas release behavior of pure Cr powder, pure Ni powder, and NiO powder were studied. Furthermore, for the alloyed steel powder mixed with carbon powder, and for the alloyed steel powder treated in steam vapor, the amount of gas release were measured. From these investigations, the effects of Cr and Ni components against the gas release behavior of the alloyed steel powder were discussed in this paper.

The Hanford Site is home to 177 large, underground nuclear waste storage tanks. Numerous safety and environmental concerns surround these tanks and their contents. One such concern is the propensity for the waste in these tanks to generate, retain, and periodically release flammable gases. This report documents some of the activities of the Flammable Gas Project Data Evaluation Task conducted for Westinghouse Hanford Company during fiscal year 1996. Described in this report are: (1) the results of examining the in-tank temperature measurements for insights into gas release behavior; (2) the preliminary results of examining the tank waste level measurements for insights into gas release behavior; and (3) an explanation for the observed hysteresis in the level/pressure measurements, a phenomenon observed earlier this year when high-frequency tank waste level measurements came on-line.

This report documents testing activities conducted as part of the Deep Sludge Gas Release Event Project (DSGREP). The testing described in this report focused on evaluating the potential retention and release mechanisms of hydrogen bubbles in underground radioactive waste storage tanks at Hanford. The goal of the testing was to evaluate the rate, extent, and morphology of gas release events in simulant materials. Previous, undocumented scoping tests have evidenced dramatically different gas release behavior from simulants with similar physical properties. Specifically, previous gas release tests have evaluated the extent of release of 30 Pa kaolin and 30 Pa bentonite clay slurries. While both materials are clays and both have equivalent material shear strength using a shear vane, it was found that upon stirring, gas was released immediately and completely from bentonite clay slurry while little if any gas was released from the kaolin slurry. The motivation for the current work is to replicate these tests in a controlled quality test environment and to evaluate the release behavior for another simulant used in DSGREP testing. Three simulant materials were evaluated: 1) a 30 Pa kaolin clay slurry, 2) a 30 Pa bentonite clay slurry, and 3) Rayleigh-Taylor (RT) Simulant (a simulant more » designed to support DSGREP RT instability testing. Entrained gas was generated in these simulant materials using two methods: 1) application of vacuum over about a 1-minute period to nucleate dissolved gas within the simulant and 2) addition of hydrogen peroxide to generate gas by peroxide decomposition in the simulants over about a 16-hour period. Bubble release was effected by vibrating the test material using an external vibrating table. When testing with hydrogen peroxide, gas release was also accomplished by stirring of the simulant. « less

The effect of cladding restraint on fission gas release behavior

Analysis of underwater gas release and dispersion behavior to assess subsea safety risk.

Calcium alginate (Ca-alginate) beads have attracted considerable attention as carriers for the controlled release of volatile compounds due to their biocompatibility and tunable properties. This study aimed to compare the release of ethylene and carbon dioxide gas from Ca-alginate beads. Ca-alginate beads were prepared from a sodium alginate solution containing ethephon and calcium carbonate as the gas-forming agent. The resulting solution was then extruded into a calcium chloride solution. The gas release behavior was studied by monitoring the concentration of released gases over time using gas detectors. Extrusion tip diameter, alginate concentration and gas-releasing agent concentration were systematically varied to assess their effect on the gas release rate. The results indicated distinct release patterns for ethylene and carbon dioxide gas. Ethylene gas exhibited a relatively slower and sustained release, while carbon dioxide gas exhibited a more rapid release. Moreover, the bead size influenced the gas release, with larger beads displaying faster release rates for ethylene and carbon dioxide gas. The concentration of alginate also played a role in modulating the release kinetics, with higher alginate concentration resulting in slower gas release. The findings have implications for designing and optimizing Ca-alginate-based systems for agricultural applications, including plant hormone delivery and modified atmosphere packaging.

Analysis of gas release during the process of thermal runaway of lithium-ion batteries with three different cathode materials

This report provides the data from the retained gas sampler, void fraction instrument, ball rheometer, standard hydrogen monitoring system, and other tank data pertinent to gas retention and release behavior in the waste stored in double-shelled Flammable Gas Watch List tanks at Hanford. These include tanks 241-AN-103,241-AN-104, 241-AN-105, 241-AW-101, 241-SY-101, and 241-SY-103. The tanks and the waste they contain are described in terms of fill history and chemistry. The results of mixer pump operation and recent waste transfers and back-dilution in SY-101 are also described. In-situ measurement and monitoring systems are described and the data are summarized under the categories of thermal behavior, waste configuration and properties, gas generation and composition, gas retention and historical gas release behavior.

Observations relating to the mechanisms of swelling and gas release in uranium dioxide at high temperatures

Compared to traditional pore structure with high porosity (≥ 80 pct) and large pore size (≥ 3 mm), aluminum foams with low porosity (60 to 70 pct) and small pore size (≤ 2 mm) possess higher compressive property and formability. In order to achieve the goal of reducing pore size, Cu-TiH2 composite powder prepared by ball milling preoxidized TiH2 with Cu powder was used as a blowing agent. Its gas release behavior was characterized by thermogravimetric analysis and differential scanning calorimetry. The results show that the ball milling treatment can advance the gas release process and slow the gas release rate at the same time. All these changes are favorable to the reduction of porosity and pore size. Such Cu-TiH2 composite powder provides an alternative way to fabricate aluminum foams with low porosity and small pore size.

Steady-state fission gas behavior in uraniumplutoniumzirconium metal fuel elements

This report describes the current understanding of flammable gas retention and release in Hanford single-shell waste tanks based on theory, experimental results, and observations of tank behavior. The single-shell tanks likely to pose a flammable gas hazard are listed and described, and photographs of core extrusions and the waste surface are included. The credible mechanisms for significant flammable gas releases are described, and release volumes and rates are quantified as much as possible. The only mechanism demonstrably capable of producing large ({approximately}100 m{sup 3}) spontaneous gas releases is the buoyant displacement, which occurs only in tanks with a relatively deep layer of supernatant liquid. Only the double-shell tanks currently satisfy this condition. All release mechanisms believed plausible in single-shell tanks have been investigated, and none have the potential for large spontaneous gas releases. Only small spontaneous gas releases of several cubic meters are likely by these mechanisms. The reasons several other postulated gas release mechanisms are implausible or incredible are also given.

Fission gas release (FGR) behavior under rapid heating conditions of high burnup UO2 fuels with developed rim structure has been examined using two different out-of-pile heating techniques with no restraint pressure. The burnups of the fuel specimens were 36–86 GWd/tU. The bare fuel specimens were heated up to 600-1,800°C at heating rates of 1.7 to 4,600°C/s. The FGR process strongly depended on fuel burnup (extent of rim structure formation) and heating conditions (heating rate, terminal temperature). At lower heating rates below about 10°C/s, growth and interlinkage of fission gas bubbles controlled FGR only at higher temperatures above the threshold temperatures of 1,250--1,450°C, depending on fuel burnup. At higher heating rates above at least 90°C/s, instantaneous FGRs, which originated from the occurrence of microcracks and fuel fragmentation induced by the overpressurization of rim bubbles, arose at higher temperatures above 700°C, only for the high burnup fuels of 74 and 86 GWd/tU with developed rim structure. Almost no FGR was found for non rim-structured fuels, even at the higher terminal temperatures of 1,500--1,800°C. From these and our previous out-of-pile heating results, a map of heating condition dependent FGR under unrestrained conditions is proposed as a function of heating rate and terminal temperature.

Fission gas release (FGR) behavior under rapid heating conditions of high burnup UO2 fuels with developed rim structure has been examined using two different out-of-pile heating techniques with no restraint pressure. The burnups of the fuel specimens were 36–86 GWd/tU. The bare fuel specimens were heated up to 600-1,800°C at heating rates of 1.7 to 4,600°C/s. The FGR process strongly depended on fuel burnup (extent of rim structure formation) and heating conditions (heating rate, terminal temperature). At lower heating rates below about 10°C/s, growth and interlinkage of fission gas bubbles controlled FGR only at higher temperatures above the threshold temperatures of 1,250--1,450°C, depending on fuel burnup. At higher heating rates above at least 90°C/s, instantaneous FGRs, which originated from the occurrence of microcracks and fuel fragmentation induced by the overpressurization of rim bubbles, arose at higher temperatures above 700°C, only for the high burnup fuels of 74 and 86 GWd/tU with developed rim structure. Almost no FGR was found for non rim-structured fuels, even at the higher terminal temperatures of 1,500--1,800°C. From these and our previous out-of-pile heating results, a map of heating condition dependent FGR under unrestrained conditions is proposed as a function of heating rate and terminal temperature.

Green micro-carbonization technology for metallurgical gas production from waste wood chips and bituminous coal: Synergistic mechanisms and gas release behavior