Radiation Physics and Chemistry (1977)最新文献

Research has demonstrated that irradiation is an effective means for reducing pathogens in sewage sludge to levels where sludge reuse in public areas meets criteria for protection of the public health. Complementary research has demonstrated the value of the irradiated sludge in both agronomic and animal science applications.

The benefits of sludge application to cropland are well documented. The irradiation process does not increase the extractability and plant uptake of a broad range of nutrients and heavy metals from sludge-amended soils. However, it does eliminate the hazards associated with pathogen contamination when applying sludge to agricultural land. Irradiated sludge has also been evaluated as a supplemental foodstuff for cattle and sheep. The data indicate that products derived from raw sewage may have a substantial nutritive value for ruminant animals.

Irradiation of sewage sludge is a practical means of sludge disinfection. Where a highly disinfected sludge is required, it should be considered as a viable sludge management alternative. Evaluation of sludge irradiation technology and its associated costs must be done with consideration of other sludge treatment processes to develop an acceptable sludge management system.

In the past 3 yr much work has been done in the G.D.R. on food irradiation. The experiments have shown that this treatment gives favourable results in many products such as spices, onions, potatoes, chicken, animal feeds, fodder yeast, drugs and vaccines. Economic aspects of food irradiation require the effective use of an irradiation plant and cobalt-60. Therefore, a new multipurpose irradiation facility was developed, applicable as an onion irradiator with a capacity of about 15 ton/h and for the simultaneous irradiation of different products (spices, animal feed, chicken, etc.) in closed product ☐es with a size of 1.2 m x 1.0 m x 1.2 m. A microcomputer controls the transport of product ☐es around the gamma sources.

An electron-attachment spectroscopy technique is described which enables the mean energy of electrons to be varied in the range 0.04–0.5 eV by means of a radiofrequency voltage superimposed on the d.c. voltage of an electron-capture detector. Plotting the electron-capture coefficients or the mean electron-capture cross sections against the mean electron energies for each compound yields a characteristic curve which may be helpful for the identification of unknown substances. An increase of the sensitivity and the specificity of the electron-capture detector is also possible. The dependence of the electron-capture coefficient on the mean electron energy for eight substances is discussed.

A laser-induced pressure-pulse apparatus (LIPP) for measuring charge-density and field-strength distributions in thick dielectric samples (some mm) with a spatial resolution of about 0.2 mm is described. First results on the charge-accumulation and storage processes in electron-irradiated polyethylene (PE), polypropylene (PP), and polymethylmethacrylate (PMMA) are presented.

CONSERVATOME SA have operated a facility at DAGNEUX near LYON, France since 1961. This operation is among the very first of its kind in the entire world. The process is based on gamma rays from Cobalt 60 of which there are three separate units. In addition there is a small experimental unit using Cesium 137. At present CONSERVATOME is owned by TRANSNUCLEAIRE and EPICEA as principal shareholders and so has the support of the French Atomic Energy Commission.

This paper describes the larger D3 unit and reviews some of the products treated at DAGNEUX.

For many years, it was believed that a clear, flame-retardant polyolefin was impossible from technical view-points. But we have developed a clear, flame-retardant radiation cross-linked polyolefin product.

This clear, flame-retardant polyolefin tubing (CFP tubing) using a special technique of material formulation has (1) transparency, (2) excellent flame resistance, and (3) good heat resistance.

Many kinds of coated or impregnated reflecting papers change color or become colored by large radiation doses. Such papers or “labels” do not generally supply dosimetry information, but may give useful inventory information, namely a visual indication of whether or not an industrial product or location has been irradiated to high doses. Among labels available worldwide, a few are suitable for indicating absorbed dose regions of slightly less than 10⁴ Gy (< 1 Mrad), and some are intended for monitoring high dose ranges (i.e., sterilization dose levels of > 10⁴ Gy or > 1 Mrad), and in some cases even up to very high dose regions (∼10⁵ to 10⁶ Gy or ∼10 to 100 Mrad). Only one labels which is expected to be commercially available, was studied for lower dose levels, 10¹-10³ Gy (1-100 krad), namely one based on polymerization of diacetylene. Tests of stability, sensitivity of ambient light, and differences in dose rate and radiation type (gamma rays and electron beams) were made on 15 kinds of labels. The results show that, for many types of indicators, diverse effects may give misleading conclusions unless countermeasures are taken. For example, some of the most commonly used labels, which contain dyes that indicate changes of pH due to release of halogen from halogenated substrates, have limited shelf life and must be protected from extreme environmental conditions. Some also show a marked rate dependence of response. Readings of color reflection optical densities on labels or long paper strips permit somewhat more precise discrimination of dose levels, and may sometimes be useful for monitoring differences in local dose distributions or area monitoring of radiation damage probabilities around particle accelerators or large radionuclide sources.

A self-contained, cesium-137 Research Irradiator with the strength of approximately 147, 000 Ci is located at the Eastern Regional Research Center (ERRC). When the irradiator was installed, the absorbed dose in a reference position of the irradiation field was calibrated and the absorbed doses in other locations of the irradiation field relative to the calibrated positions were measured to map its irradiation field. Self-read pocket dosimeters for gamma-ray were calibrated with a 120 M Ci Calibration Cs-137 source which delivered about 50 mR exposure during a 20-min irradiation at 50 cm from the source. A ferrous sulfate/cupric sulfate solution was used to calibrate the dosimetry of the irradiation chamber which holds three number 10 cans (16 cm inside diameter X 17.5 cm height each). At 20-min exposure, Dmax:Dmin = 1.35, except at the top and bottom $\text{1}\text{3}$ portions of the cans, all positions received a more or less uniform dose (about 0.13 kGy/min) during irradiation. A straight line of total dose (kGy) vs time (min) was constructed following the equation y = 0.127 + 0.137 with r = 0.99, where y is the total dose, and x is time. Radiochromic films and PVC strips were also used to monitor the irradiation operation after comparing results obtained from the chemical dosimeter. Two equations were constructed, respectively, as follows: y = 0.0091x + 0.0015 with r = 0.99, where y = absorbance and x = time (min), and y' = 0.0041x' + 0.0185 with r = 0.99, where y' = absorbance and x' = time (min). Controlled environment is important when such chemical and solid state dosimeters are used during irradiation at subfreezing, refrigerated, or ambient temperature conditions; the equipment has this capability.

The radiation chemical reaction of CO-H₂ mixture up to 8.4 x 10⁵ Pa has been studied. The G values of oxygen containing organic compounds except methanol increased with increasing total pressure of reactant. The G values of most of products except trioxane and tetraoxane were increased with raising of temperature in the range from 210 to 350 K, while the G values of trioxane and tetraoxane reached the maxima at 243 K and decreased rapidly with raising of temperature. From the dependencies of G values of these cyclic ethers on pressure and temperature of the reactant, it is considered that these cyclic ethers produced from the neutralization reaction of HCO⁺ (CO)_n cluster ions with electrons in an atmosphere of relatively large amount of hydrogen. The effects of CO content on G values of products did not change with the pressure change of the reactant.

Electron-beam and UV radiation can induce covalent attachment of unsaturated monomers onto a variety of polymer surfaces. The surface characteristics of a polymeric material can therefore be precisely manipulated by grafting the proper combination of monomers onto the surface. Radiation-grafted, sterically nonhindered tertiary acrylamides behave surprisingly well as primers for acidic pressure-sensitive adhesives. Physical and spectroscopic analyses of grafted acrylamides indicate that this unusual behavior is due to hydrogen bonding between the amide functionality in the primer and the acid functionality in the adhesive. Primary and secondary acrylamides are postulated to be less effective because they have the tendency to form hydrogen bonded dimers within the primer rather than interacting with the adhesive.