Gaseous release

There are a number of factors that determine the release rate and initial geometry of a hydrocarbon gas release. The most significant is whether the gas is under pressure or released at atmospheric conditions. Depending on the release source the escaping gas can last from several minutes or days, until the supply is isolated, depleted or fully depressured. Common long duration sources are underground reservoirs (e.g., blowouts), or long pipelines without intermediate isolation capabilities. 

If released under atmospheric conditions the gas will either rise or fall depending on its vapor density and will be directed in the path of the prevailing wind. In the absence of a wind, heavier gases will collect in low points in the terrain. Normally atmospheric gas releases are dispersed within relatively close distances to their point source, usually about 3 meters (10 ft.) (Reference NFPA 30, Table 5-3.5.3). These atmospheric releases, if ignited, will bum relatively close to the source point, normally in a vertical position with flames of short length. 

For gases released under pressure, there are a number of determining factors that influence the release rates and initial geometry of the escaping gases. The pressurized gas is released as gas jet and depending on the nature of the failure may be directed at any direction. All or part of a gas jet may be deflected by 

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Calculates impact of gaseous releases under routine or accident conditions. 

Peak Core Averaged Gaseous Releases Comparison of Predicted-Releases... 

PEAK CORE-AVERAGED GASEOUS RELEASES COMPARISON OF PREDICTED RELEASES AND CRITERIA... 

This chapter deals with some simple and quick methods for the evaluation of the dispersion in the environment of gaseous releases (gases, volatile products, aerosols and particulates). Chapter 7 describes some methods for evaluating the health consequences of releases. 

The gaseous releases which are dealt with here, are the most relevant ones for the evaluation of the immediate accident consequences and for the preparation of short-term emergency plans. Solid and liquid releases are less important for a nuclear power station because the radioactive products released to the environment are mainly gaseous and have high velocity (which may cause adverse consequences outside the plant). However, liquid releases have to be taken into account under some circumstances. The situation, then, is very different from many non-nuclear process plants where the prevailing accidental release from the point of view of the consequences may frequently be the release of flammable or toxic liquids. 

The integrity of the containment system can be evaluated in many ways. For example, the radioactive release from the containment system can be calculated on the basis of the volnmetric (e.g. gaseous) release. 

Plant Name Containment Venting Filters Passive Iodine Removal Iodine Mitigation measures Measurement of airborne iodine in containment Measurement of controlled iodine (gaseous release into environment Other AM measures to mitigate (1) airborne iodine in containment... 

The releases of C from the plants with liquid and solid wastes are small, being less than 5% of the gaseous releases (Kunz, 1985). 

The third scenario with turbulent gaseous release may also be considered to be rather probable. It has been investigated independently by BASF for subcritical jets of natural gas and hydrogen and by Battelle for supercritical jets of propane. The purpose of the Battelle experi-... 

A large portion of the carbon 14 gaseous releases from gas-cooled reactors comes from the purification of the CO2 circuits used to cool the reactor and from the isotopic exchange between the moderator and the CO2 circuit. 

Since the average concentration of carbon 14 in the moderator graphite is 2x10 Bq/g, the gaseous releases from an incinerator capable of processing 600 tonnes of graphite a year will be 12 x 10 2 gq j e 320 curies per year. 

U5 This ultimate procedure of depressurization and gaseous release filtration is used when a slow increasing of pressure occurs in the containment after a severe accident. To maintain containment integrity a prefilter with metallic medium (located in the containment) and a sand filter (external to the containment) are manually operated where necessary to mitigate radiological impact in the environment to an acceptable level. 

Hydrocarbon materials must be first in a vapor condition before combustion processes can occur. For any gaseous material this is an inherent property. Liquids, however, must have significant vapor emissions in order for flammable concentrations to be present for combustion processes to occur. Therefore, hydrocarbon liquid releases are relatively less dangerous than gaseous releases. 

The ventilation of buildings may be a source of gaseous release and, to a less extent aerosols. The main isotopes are (from evaporation of the pools) and "Ar. 

The release of corrosive gases or liquids (including hot steam and gas) from industrial plants close to the site or in transit, such as in accidents and spills from shipping or trains, constitutes a potential hazard. Leakage of corrosive gases and liquids may also occur from stores of chemicals on the site. Usually, since gaseous releases from such sources are required to be within toxicity limits, which are well below corrosive levels, they will not pose a serious threat to the equipment. 

For the liquid metal fast breeder reactor, of the pool type, the main gaseous release of radioactivity in normal operation arises from leakage of... 

Time of maximum height of gaseous release curve. 

Table 4. Development and Gaseous Release Characteristics of Doughs from...

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