Irradiation facilities

Radiation Safety of Gamma and Electron Irradiation Facilities, Safety Series No. 107, International Atomic Energy Ageney, Vienna, 1992. 

Azarra, M. A. et al., 1990a, Level-1 for High Flux Beam Reactor (HFBR) Accident Sequence Delineation, ANS Topical Meeting, The Safety, Status and Future of Non-Commercial Reactors and Irradiation Facilities, Boise, ID, Sept. 31 - Ott. 4, 1990. 

HS(G)94 Safety in the design and use of gamma and electron irradiation facilities... 

Sometimes expensive for tracers or irradiation facilities. Special laboratory and handling facilities required. Needs highly skilled operators, and complex instrumentation. 

Because of the gradual loss of neutron irradiation facilities (and the general public unpopularity of nuclear sciences), NAA is being slowly replaced by other techniques, chiefly ICP-OES, and more recently ICP MS, which has comparable sensitivity. It has, consequently, become necessary to carry out research comparing these techniques since there is a need to know how compatible ICP data are with the vast databanks (such as the Aegean databank discussed above) of NAA. This has included comparison of NAA with ICP OES on bone (Akesson et al. 1994) XRF and NAA on ceramics (Garcia-Heras et al. 2001) NAA, XRF, ICP-OES, and ICP MS on ceramics... 

Typical irradiation facilities consist of a process chamber containing the radiation source, some sort of conveyor systems to transport products inside and outside the shielding walls, and sophisticated control and safety systems. Irradiation facilities are built with several layers of redundant protection to detect equipment malfunctions and protect employees from accidental exposure. Technical details depend on the type of irradiation. Typical processing parameters are compared in Table 2 [7]. 

Artificial satellites, which are now used for communication, broadcast, weather forecast, etc., are equipped with a variety of semiconductor devices, which are often exposed to the high levels of radiation found in space. Such energetic particles, called cosmic rays, cause the degradation and malfunction of semiconductor devices, which lowers both the mission lifetime and reliability of satellites. Using ion beam irradiation facilities at TIARA, which have been uniquely adapted for simulating the radiation environment of space, we have... 

ISO/ASTM 51204 Standard Practice for Dosimetry in Gamma Irradiation Facilities for Food Processing... 

A cobalt-60 source of about 40 curies was used for irradiation. The irradiation facility is of the shielded room type. Dosimetry of the highest... 

We wish to thank Dr. T. N. Bowmer, Miss S. Y. Ho, Mr. R. W. Garrett, Mr. P. W. O Sullivan, Mr. D.A. Lewis, Mr. A. K. Whittaker and Miss E. Grespos for experimental work Mr. O. Delatycki and Mr. J. Hedrick for preparation of polymers Prof. J. E. McGrath and Mr. G. Sykes for collaboration The Australian Research Grants Scheme and the Australian Institute of Nuclear Science and Engineering for supporting our research the AAEC for irradiation facilities. 

Several major differences existed between this scheme and one compatible with the PBR facilities. The PBR did not have an operating pneumatic transfer irradiation facility, nor was there a sophisticated y-ray spectrum analysis and data reduction computer program available. Irradiation facilities at PBR were hydraulic. Aluminum capsules (rabbits) were used to contain and transfer samples to and from the core. 

Decay time was critical to the determination of elements from the 5- and 30-min decay counts, so we decided to use the rabbit irradiation facilities with the highest thermal neutron flux (1014 n/cm2/sec) to build up the specific activity of short-lived isotopes. The higher flux also provided a greater sensitivity. 

Activation analysis is not without its drawbacks, however. Among them are the need to use expensive equipment and irradiation facilities, the inability to determine the chemical state of the elements in question, the need to work with significant levels of radioactivity, with their attendant radiation safety and legal problems, the long times needed to complete some analyses, and complex analysis sometimes needed to unscramble the y-ray spectra in a given experiment. 

The second step in an activation analysis concerns the choice of nuclear reaction to change X into X, plus the irradiation facility in which the reaction will be carried out. In addition, the length of irradiation and decay prior to counting must be chosen so the produced X activity is enhanced relative to all other activities produced. Most activation analysis is done with thermal neutrons produced in nuclear reactors for the following reasons ... 

The canned, frozen samples were shipped to and returned from the cobalt-60 irradiation facility at the U.S. Army Natick Laboratories, Natick, Mass., packed in dry ice, and allowed to remain at — 80°C. for 2 weeks, then at — 20°C. for 2 weeks before thawing for analyses. This was done to permit reaction and slow thermalization of long half-life radicals at low temperatures, as well as to prevent spillage and thermal deterioration. 

Effect of Grade, Cut, and Animal Variations. Samples were prepared from the half loins (rib eye) and top rounds of two U. S. Choice and two U. S. Commercial grade beef carcasses. Half of each set of samples received 6.0 db 1.5 megarads of irradiation at — 196°C. at the Natick irradiation facility. The other half of the samples was frozen and held as unirradiated control. 

Establishing a Food Irradiation Facility, and Related Economic Aspects... 

The cans of ground meat were divided into equal groups and irradiated according to the scheme in Table I. All samples were irradiated at ambient temperature at the Food Irradiation Facilities of the U. S. Army Natick Laboratories, Natick, Mass. 

The microbiological studies above are conducted to establish the appropriate dose level to be used to sterilize each specific product or commodity to an acceptable level of statistical nonsterility. These studies should be conducted following qualification of the irradiation facility. The Health Industry Manufacturers Associ-aton (HIMA) [39] has suggested major items to be included in the qualification phase of the validation scheme for radiation sterilization installation. 

The impact of DMDOHEMA-TPH radiolysis under continuous degradation was studied in the laboratory-scale MARCEL y-irradiation facility. A retention of Mo in the DMDOHEMA-TPH solvent was observed (about 30-40% of Mo was missing from the aqueous phase), which has been linked to the MDOHEMA accumulation (217). 

After long-term degradation in the MARCEL y-irradiation facility, no influence was observed on the physical properties of the DMDOHEMA-TPH solvent (density, refraction index, interfacial tension), but a slight increase of solvent viscosity was observed (217). 

Ion beams were obtained from a single-ended Van de Graaff generator (terminal voltage 0.4-3.75 MV) at the High Fluence Irradiation Facility, University of Tokyo. 

In this study the filter samples were halved, bagged in cleaned polyethylene tubing, and first analyzed by PGAA using an external irradiation facility constructed by our group at the National Bureau of Standards (NBS) research reactor (9). PGAA provided determinations of the elements B, S, and Cl on the treated filters, and B, S, Cl, Si, Cd and often others on the particle filters. For analysis of short-lived isotopes by INAA, the bagged samples were... 

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