Irradiation capsule

TFEt Tetryl 2,4,6-Trinitrophenyl-/S,j8,j8 trifluoroethylnitramine are reported by Avrami et al (Ref 2). Their behavior at different exposure levels is compared with the behavior of the parent compds, TNB TNT RDX HMX are also included as controls. The determinations made on each expl were wt loss, vacuum, stability, mp, IR spectra, DTA, TGA, impact sensitivity, expln temp, and rate of detonation as a function of total gamma exposure. A brief description of the expln-containment irradiation capsule designed used in these studies is also given... 

In utilizing nuclear reactors (or any radioactive source) for the irradiation of expls, proper precautions have to be taken to prevent any damage to occur to the reactor or source in the event of an expin. This led to the development of especially designed expin-proof irradiation capsules (Refs 63, 130, 156, 186, 192 194)... 

The DTA thermograms indicate for each type a shifting downwards of the exotherm at the 1.0 x 10SK level. The IR spectra for the various Pb azides reveal that a form of Pb carbonate is evident at the higher exposure. This is probably the reason for the lower values in the vacuum stability test listed is Table 11. Another interesting feature was the formation of ammonium nitrate on top of each Pb azide and thallous azide irradiation capsule (as shown in Fig 16) subjected to over 109R... 

A. Mackenzie E.W. Dalrymple, Burst Test Results Simplify Design of Irradiation Capsules for Explosive Materials , Nucle-... 

The NAA method for the determination of firearm discharge residue has been generally accepted, but applications have been limited to just a few laboratories. In the process of establishing NAA capability for the State of Illinois crime laboratories we re-examined the standard techniques (10). In the course of our work it became clear that post-irradiation is the cause of several constraints which have discouraged a more widespread use of NAA. The inherent time limitation due to the 87 min. half-life of 139Ba necessitates fast manipulations of radioactive solutions which in turn requires an experienced radiochemist. In addition to an ever present danger of overexposure and contamination, typically only a dozen samples can be irradiated per batch, which makes the method quite expensive. The developed statistical bivariate-normal analysis (11) is convenient for routine applications. With this in mind, a method was developed which a) eliminates post-irradiation radiochemistry and thus maximizes time for analysis b) accommodates over 130 samples per irradiation capsule (rabbit) c) does not require a collection of occupational handblanks and d) utilizes a simplified statistical concept based on natural antimony and barium levels on hands for the interpretation of data. The detailed procedure will be published elsewhere (15). 

Lee, J. D. Werner, R. W. "Concept for a Gas-Buffered Annular Heat Pipe Fuel Irradiation Capsule" Lawrence Livermore National Laboratory Livermore, CA, UCRL-50510, 1968. 

Avrami and Voreck (Ref 192) reported on a transient radiation test in which a group of nine expls and proplnts in expln-proof irradiation capsules were subjected to a transient burst of energy of about 1 millisecond duration which resulted from fission of about 10 atoms of. One set of nine capsules was attached to the KIWI reactor pressure vessel and another group on the support structure as part of the KIWI-B4-E excursion expt conducted by Los Alamos Scientific Laboratory at the Nevada Test Site. The materials selected were TATB, DATB and TACOT as the secondary expls, HNS as the booster expl, Pb styphnate as the primary expl, BlkPdr as the igniter, and three composite proplnts. Each capsule contained 3.6 grams of the selected material... 

The irradiation capsule tests of molten salts that used a purged gas space are the most revealing. Xenon and krypton fission products were detected in these purge-gas samples. Very small amounts of iodine and tellurium were found in a few tests, and these values are consistent with the precursor transport of xenon and krypton. 

Series Number of available locations Irradiated capsules at start-of-life Design lead factors... 

Some environmental conditions may cause deterioration of structure or equipment through chemical reactions other than corrosion, e.g. reaction of the structure or equipment with ozone or NOj. Use of chemicals may cause damage to equipment. Special care should be taken when irradiating capsules containing materials such as copper or mercury which may cause strong corrosion in aluminium alloys. 

Type and Quantity of Specimens Contained In Each Irradiation Capsule Assembly... 

Fast neutron flux measurements are obtained by insertion of threshold detectors into each of the six irradiation capsules. Such detectors are particularly suited for the proposed application, because their effective threshold energies lie in the range of interest (0.5 to 15 MeV). 

TYPE AND QUANTITY OF SPECIMENS CONTAINED TN EACH IRRADIATION CAPSULE ASSEMBLY... 

A basic requirement for accurate NAA is the correct characterization of the irradiation facility (Becker 1987). Local and temporal neutron flux density gradients as well as gradients in the neutron energy spectrum of the irradiation position must be well understood and known for each irradiation. O Figure 30.5 illustrates the gradients in an irradiation capsule as measured by flux monitor foils. A difference of 1 mm in sample positioning will result in a 0.6% relative difference in the measured concentration. 

Flux gradient within an irradiation capsule in the NIST CNR reactor RT-4 pneumatic tube irradiation facility (mean flux 3.4 x 10 cm s ). The vertical axis was determined using Zn foils as monitors, where values are percent Zn found when compared to a foil in position 0 cm. The essentially linear drop-off in neutron flux between positions 20 mm and 60 mm provides a roughly even effective flux (see upper curve) when the capsule is turned halfway around its vertical axis (i.e., by 180°) at the midpoint tn,/2 of the irradiation... 

Lap shear specimens were made of 2850 FT epoxy and EF-527 B-stage composite, with beryllium-copper pull-tabs. A molding jig ensured specimen uniformity. These specimens were nested to save space in the irradiation capsule. 

The limited space available in the irradiation capsule, as well as the neutron flux gradient over the capsule, require that the activation detectors have small dimensions ideally, the monitor element is a constituent of the material under investigation, so that no particular detector is required. 

Figure 6.2. Isolde irradiation capsule (schem.) (Kiihnlein et al., 1993)...

The reactor facility should develop encapsulation techniques for the range of fluxes, fluences and irradiation environments available there. After irradiation, a shielded device, often in a fume hood, must be available for opening irradiation capsules safely. 

The initial investment for a facility to perform dating irradiations involves the in-core irradiation facilities. Most reactors already have such irradiation positions. For the analysis of older rocks, a Cd lined facility is not required. For the analysis of young rocks, it is essential. If such a facility is not available, it could be installed for a few thousand dollars or less. The only recurring expense is for irradiation capsules and shipping materials. 

Initial plans were to load each irradiation capsule with five foam samples however, due to the size of the capsules, only three foam samples, plus a chemical vapor deposition (CVD) SiC temperature monitor, fit in each capsule. Two of the capsules were used for the IP samples, and the other two were used for the OP samples a total of 12 foam samples were irradiated at ORNL s HFIR. Table 4.4 lists the content of each capsule and the neutron irradiation dose received by each capsule. The location of the capsules within the hydraulic tube (see Fig. 4.19, position 3-4) was such that the variation of the neutron flux was less than 15% from capsule to capsule. The planned irradiation temperature was 600°C however, the actual irradiation temperature was considerably higher (as explained in the next section). 

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