Irradiation chamber

The dose-rate was varied by lining the irradiation chamber of the gamma cell irradiation by lead foil of uniform thickness [17]. The dose was kept constant at 0.15 and 0.35 KGy for copolymerization of AM-AANa and AM-DAEA-HCl system, respectively. The results are shown in Figs. 2 and 3, which show that the rate of polymerization, Rp increases while the degree of polymerization (DP ) and the intrinsic viscosity [17] decrease with the dose-rate. The exponents of the dose-rate for AM-AANa system [17,54] were determined to be ... 

For the analysis of large objects which cannot be placed within the irradiation chamber it is possible take the particle beam into the ambient air through a thin window at the end of the beam line. In this way any type of object can be analysed -for example paintings and archaeological artefacts. 

Glasson, W. A., and A. M. Dunker, Investigation of Background Radical Sources in a Teflon-Film Irradiation Chamber, Environ. Sci. Technol., 23, 970-978(1989). 

C=0 bonds likely develop by reaction of the exposed surface to air during sample transfer from the irradiation chamber C=CF bonds develop during irradiation. In addition, the CF2 vibration at around 1200 cm-1 broadens towards lower wavenumbers, indicative of defluorination (26). 

Fig. 8.11 Two UviTox photoreactor modules connected in series. Each module contains a MP Hg lamp of PeV = 30 kW. The tangential injection technique (I) generates a rotating water column within the irradiation chamber of the photoreactor reproduced by permission of VitaTec UV-Sys-teme GmbH (Freigericht, Germany).

Reaction Bags and Irradiation Chamber. Teflon (50-mil FEP Type C) bags of 32 inches X 48 inches were fabricated by impulse heat sealing. The bags were fitted with glass ball joints to connect them to the TEE Teflon sampling lines. 

Experiments conducted in the large 335-ft irradiation chamber also showed that in most cases the effect of ambient concentrations of CO on the oxidation rate of NO to NO2 is negligible. The results for three series of runs, one involving only paraffins, one involving paraffins and more reactive hydrocarbons, and one involving no hydrocarbons, are shown in Table III. The various hydrocarbons and their relative concentrations were chosen to represent the Los Angeles atmosphere as determined by Kopczynski and co-workers 14). All runs were conducted at 50% relative humidity. 

Table III. Photooxidation of Hydrocarbon—NOar-CO Mixtures in Large Irradiation Chamber...

The authors are grateful to Mr. Stanley L. Kopczynski for the use of his data obtained in the large irradiation chamber. 

In the domain of contract sterilization, continuous processing in cobalt-60 radiation facilities has proved to be economically competitive with other sterilization methods, especially in the area of medical devices and packaging. When using a continuous carrier irradiator as described by Masefield et al., the materials are loaded onto the carriers and introduced into the irradiation chamber on a timed sequence. The carriers make four passes around the source, stopping at each carrier position for a certain time before being shuttled to the next position. The throughput is a function of the radiation dose required, the density of the device,... 

The dilatometer was so immersed in a thermostat, that the onionlike vessel with its stirring fish exactly matched an underwater stirrer magnet in the thermostat. The whole apparatus was reproducibly fixed in the irradiation chamber. To avoid creaming, the emulsion was stirred throughout the polymerization reaction. 

The water is treated with UV radiation for primary disinfection, then chlorinated for secondary disinfection. An applied chlorine dosage of only about 1 mg/L is necessary. The entire water treatment system is housed in a 2.97 m (32 fU) building. The UV disinfection system consists of six irradiation chambers, two control cabinets with alarms, chart recorders, relays, hour-run meters, lamp and power on-lights, six thermostats, electrical door interlocks, mimic diagrams, and six UV intensity monitors measuring the total UV output. Each irradiation chamber contains one 2.5-kW mercury vapor, medium-pressure arc tube, generating UV radiation at 253.7 nm. 

The system is equipped with a telemetry control system and a fully automated backup system. Each bank of three irradiation chambers has two units on line at all times, with the third unit serving as a backup. In the event that the UV intensity decreases below acceptable limits (20,000 pW-s/cm ) in any of the chambers, the automatic butterfly valve will close, stopping flow through the chamber at that time, the automatic butterfly valve on the standby unit will open. The alarm system is also activated if UV intensity decreases below acceptable limits in any of the chambers. The UV alarm system is interfaced with the automatic dialer and alarm system. In 1987, total equipment costs for the six-unit UV irradiation system with butterfly valves was US 74,587. 

Figure 1 Scheme ofa gamma irradiation facility (usually 1 to3x 10 Ci, i.e. about 7 O Bq). When not used, the Co radiactive source is stored down in the pool. During irradiation, the source is raised to the upper position and parcels are moved in front of and around the source. A thick concrete shielding surrounds the irradiation chamber. 

The EBDS process is shown schematically in Fig. 12.3, An electrostatic precipitator is used to remove flya,sh from the flue gases before they pass to the treatment system to prevent contamination of the fertilizer byproduct. The flue gas is then cooled from about 200°C to 60-80°C in a water spray cooler, and ammonia is added. The conditioned flue gas enters the irradiation chamber (reactor), where high-energy electrons generate hydroxyl (OH) and hydroperoxyl (HOi) radical-s by collision with the water molecules. These radicals play the major role in the formation of sulfuric and nitric acid,s that react with ammonia to form the sulfate and nitrate. 

Treatment of Data. Chemical measurement data in each irradiation chamber experiment are plotted as concentration vs. time, and the rates and dosages are determined from the points and best-fit experimental curves. The name of the compound and initial chamber concentrations are entered on computer cards along with the following observations ... 

However, studies of solvents with nitrogen oxides in irradiation chambers reveal mechanisms by which innocuous traces of materials can be transformed into photochemical smog. Useful generalizations have been derived from such investigations and are reviewed below. 

Alkanes. In most of the chemical reactions observed in irradiation chambers, saturated hydrocarbons—even highly-branched ones such as p-menthane (l-isopropyl-4-methylcyclohexane)—have been quite unreac-tive. Since attack of alkanes by hydroxyl radical (26), atomic oxygen (27, 28), or ozone (29) follows the C-H reactivity order, tertiary > secondary > primary, the chemical measurements with alkanes would be expected to follow a clear pattern. However some alkanes (e.g., p-menthane) with tertiary hydrogens do not react more rapidly than those (e.g., n-octane) with only secondary and primary hydrogens, and hydrogen abstraction reactions often do not appear to be rate-determining steps. 

Ketones. The individual reactivities of ketones were measured in several irradiation chambers, including those of Battelle (4, 35) and LA-APCD (2, 3). In addition to the data given in Tables I to III for ketones in the steel chamber, we present Table V with experimental findings for ketone irradiations in the small glass chamber. Fairly good agreement exists between the relative chemical reactivities observed for several ketones in the different investigations. 

Aerosol formation in aii irradiated chamber (Friedlander, 1978). N particle number V volume of particles A total particle surface. (By courtesy of Atmospheric Environment)... 

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