Holding period

Several modes of waste management are available. The simplest is to dilute and disperse. This practice is adequate for the release of small amounts of radioactive material to the atmosphere or to a large body of water. Noble gases and slightly contaminated water from reactor operation are eligible for such treatment. A second technique is to hold the material for decay. This is appHcable to radionucHdes of short half-life such as the medical isotope technetium-9 9m = 6 h), the concentration of which becomes negligible in a week s holding period. The third and most common approach to waste... 

M Preparation of isopropyiidene peniciiiamine hydrochioride To the filtrate obtained In step (b) is added at 20°C to 25°C a total of 85 g of hydrogen sulfide. The precipitated HgS is filtered off and the filtrate is concentrated under reduced pressure to a volume of 200 to 500 ml. Following e polish filtration, the product-rich concentrate is mixed with 1.5 liters of isobutyl acetate. The mixture is refluxed at about 40 C under reduced pressure in equipment fitted with a water separation device. When no further water separates, the batch is cooled to 30t and filtered. The reactor is washed with 1 liter of acetone, which Is used also to wash the cake. The cake is further washed with 200 ml of acetone. The acetone washes are added to the isobutyl acetate filtrate and the mixture is refluxed for 20 to 30 minutes. After a holding period of one hour at 5°C, the crystals of isopropyiidene penicillamine hydrochloride are filtered and washed with 200 m of acetone. On drying for twelve hours at 25°C this product, containing 1 mol of water, weighs about 178 g (73%). 

In curing thick articles in open steam it is sometimes necessary to reduce the temperature of cure at the end of the hold period at a slow yet uniform rate. This part of the cure schedule is the drop . 

If leakage is indicated during the hold period, the pressure may be reduced while locating the leak. After the leak is repaired, a new hold period must be started at full test pressure. 

Application of ion exchange refining to the process for the manufacture of dextrose may be understood from the following description of such a process. Triple-washed starch is diluted with ion-free water to the desired concentration and is acidified with a definite quantity of mineral acid such as hydrochloric or sulfuric. It is desirable that the acidified starch slurry be held for at least thirty minutes in order to permit an effective equilibrium acidity to be reached. The starch slurry may contain a quantity of soft water salts which consume acid, and since this consumption is variable, the acidity is checked and adjusted to the desired level following the holding period. The conversion is then carried out at elevated temperature and under pressure for a period sufficient to yield maximum dextrose. The conversion may be carried out batchwise in an autoclave, or continuously. 

Modifying this procedure, another potential holding period was set after removing the adsorbates. This potential should not cause methanol oxidation and be low enough to facilitate the reconstruction. 

Identify topics of importance to the chemical science and technology community by holding periodic discussions and presentations, and gathering input from the broadest possible set of constituencies involved in chemical science and technology. 

When dealing with small, hermetically sealed parts where the enclosure is leaky, krypton 85, a gaseous, radioactive isotope, can first be forced into the device by applying pressure from the outside. Once an exactly measured holding period has elapsed the pressure will be relieved, the component flushed and the activity of the gas charge will be measured. In the same way it is also possible to use helium as the test gas (see Section 5.7.4, bombing test). 

Cool as rapidly as possible after the hold period. 

A typical cure cycle used to process many thermoset epoxy composite parts is shown in Figure 10.3. It contains two ramps and two isothermal hold periods. The first ramp and... 

Once the medium has been processed, it is held for a period of time at least equal to that for aseptically produced materials. Any aseptic manipulations performed during and at the end of the hold period should be simulated as well (i.e., sampling, refiltration, hold times, and product recalculation). 

Procedures used to protect microbiological quality of the bulk drug during these holding periods should be indicated. Maintenance of the microbiological quality during holding periods may need verification. 

Any of aseptic manipulations performed during and at the end of the hold period should be simulated hold times and product recalculation. 

The test bars of the Nile mud were reddish brown (5YR 5/4) in the Munsell color notation at the 600°C zone of the gradient firing, red (2.5YR 5/6) at 850°C, and darkened with incipient vitrification to weak red (2.5YR 4/3) at 1100°C after a holding period of 30 minutes. The scratch hardness, using Mohs scale, increased from 3.0 to 6.5 for the male (better working clay in the potters terminology), and from 2.3 to 5.0 for the female mud. The Nile mud shrank far more when fired... 

At the end of the hold period, add 20 ml of KI solution, then immediately add 100 ml of distilled water. Swirl lightly to mix, then promptly titrate, with vigorous shaking/stirring, with 0.1N sodium thiosulfate using a 50-ml buret. Continue titrating until the yellow-brown color has almost disappeared, then add 1 to 2 ml soluble starch indicator and continue to titrate until the blue/brown color has just disappeared. Record the volume of sodium thiosulfate that was used. 

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