Plutonium losses

C minimises plutonium loss ia the filtrate and decreases filtering time (166). Heating the compound to ca 270°C ia air or to 460°C ia absence of air results ia the formation of PUO2. Yellow-green Pu(IV) oxalate [26588-74-9] Pu(C20 2 6H20, precipitates from acidic solutions of Pu(IV) upon addition... 

In addition, some plutonium is also lost to the salt as PuCl3. A two-step counter-current extraction is used to minimize the amount of salt used in the MSE process, reduce plutonium losses... 

Both methods have been used at various times, but the counter-current method is the preferred technique as it minimizes salt use and plutonium losses. 

Crosscurrent extraction was used initially at Rocky Flats. This mode of extraction has the following disadvantages (1) the solvent capacity of the salt is not used effectively, (2) plutonium loss to the salt is high because two salts must be... 

Countercurrent extraction is favored over crosscurrent extraction at a fixed salt composition for the following reasons (1) less salt is required to obtain the same separation, (2) plutonium loss to the salt is lower, (3) less magnesium metal by-product is generated, and (4) salt feed to the salt recovery line is cut in half. 

Plutonium—is very soluble in the process alloy so only through coprecipitation will any follow the uranium stream. There will be some plutonium loss during the FP-3 extraction but should be <0.4% with proper choice of alloy and salt. 

The Purex Process has been used either with "early" or with "late" Pu-U partitioning (Fig. 1). The early split in the first cycle avoids the co-stripping of uranium and plutonium which may result in higher plutonium losses. In other flowsheets, the partitioning is delayed until the second cycle. While no particular trend has been obvious, some of the recent flowsheets in which the plutonium is reduced prior to re-extraction (10,11) will necessarily require a second cycle partitioning. 

Nondestructive-type instrumentation is used to assay each scrap package before it enters the process, and Nal single-channel analyzers are used to note inventory buildups by measurement of the 414 keV of Pn. Also, continuous specific gravity and nitric acid concentration instruments help assure low plutonium losses to the waste system. Both gamma and neutron counting num-itors are used to measure plutonium content of waste streams and waste tanks. Figure 1 shows a simplified sketch of the PRF and its instrumentation for criticality prevention. Figure 2 shows how inventory buildup within the reflux solvent extraction system is monitored by neutron counters. ... 

Uranium Purification. Subsequent uranium cycles provide additional separation from residual plutonium and fission products, particularly zirconium— niobium and mthenium (30). This is accompHshed by repeating the extraction/stripping cycle. Decontamination factors greater than 10 at losses of less than 0.1 wt % are routinely attainable. However, mthenium can exist in several valence states simultaneously and can form several nitrosyl—nitrate complexes, some for which are extracted readily by TBP. Under certain conditions, the nitrates of zirconium and niobium form soluble compounds or hydrous coUoids that compHcate the Hquid—Hquid extraction. SiUca-gel adsorption or one of the similar Hquid—soHd techniques may also be used to further purify the product streams. 

At development of a proeedure for optimization of requirements of seleetion of plutonium and the detenuinations of stages on whieh oeeur losses of plutonium used gamma-emitting isotope of plutonium Pu. In the report the data s on losses of plutonium at all stages of radioehemieal seleetion ai e redueed. 

Since the energy required to strip the electrons from plutonium metal at the anode is exactly matched by the energy returned at the cathode, the potential required by the process is only that required to overcome time invariant (i2r) losses in the cell circuit, and time dependent resistance (electrode polarization). 

In all cases a significant fraction of the plutonium remained immobilised on the leaves, both citrate and nitrate showed a 60—90% loss in solubility. It is possible that the reduced leachability of the plutonium may have been due to the entrapment of the compounds in crevasses on the leaf surface, engulfment by expanding epidermal plates, or by adsorption onto unsatisfied valences. 

Americium and curium injected into animals are distributed to the extent of about 25 per cent in bone, but unlike neptunium and plutonium, about 70 per cent of the injected dose is found in the liver. Loss from the... 

Buck, E. C., Finn, P. A. Bates, J. K. 2004. Electron energy-loss spectroscopy of anomalous plutonium behavior in nuclear waste materials. Micron, 35, 235-243. 

An increase of product loss, namely, uranium and plutonium, in aqueous raffinates (84, 101). 

The crown ethers were investigated mainly for the removal of Sr or Cs from nuclear-waste streams (246-250), and some studies reported their interest as selective extractants of plutonium (251). Different crown ether derivatives with the addition of alkyl chains have been examined, in order to increase the lipophilicity of the molecule and prevent major extractant losses due to high solubility in aqueous phases. These extractants were described as radiolytically resistant, and their stability increased in the order benzocrown > dicyclohexanocrown > crown (44). 

The uranium and plutonium streams flow separately through second sets of two columns for re-extraction and stripping for further separation from fission products, according to the scheme shown for Pu in the lower portion of Fig. 21.20. The acid waste streams from the second cycles may be recycled to the first to eliminate the second cycle losses. 

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