Search Results

You are looking at 41 - 50 of 701 items for :

  • "Plutonium" x
  • Refine by Access: All Content x
Clear All

Abstract  

Electrochemically modulated separations (EMS) are shown to be a rapid and selective means of extracting and concentrating Pu from complex solutions prior to isotopic analysis by inductively coupled plasma mass spectrometry (ICP‐MS). This separation is performed in a flow injection mode, on‐line with the ICP‐MS. A three‐electrode, flow‐by electrochemical cell is used to accumulate Pu at an anodized glassy carbon electrode by redox conversion of Pu(III) to Pu (IV&VI). The entire process takes place in 2% (v/v) (0.46 M) HNO3. No redox chemicals or acid concentration changes are required. Plutonium accumulation and release is redox dependent and controlled by the applied cell potential. Large transient volumetric concentration enhancements can be achieved. Based on more negative U(IV) potentials relative to Pu(IV), separation of Pu from uranium is efficient, thereby eliminating uranium hydride interferences. EMS‐ICP‐MS isotope ratio measurement performance will be presented for femtogram to attogram level plutonium isotope injections.

Restricted access

Abstract  

The segmented gamma ray scanning system developed for the assay of plutonium present in 200 L waste drums was modified for the estimation of gram amounts of plutonium in the presence of high beta gamma activity. A multi gamma ray source of 152Eu having ~1 mCi activity was used for the determination of attenuation correction factors for high count rate drums. Dead time corrections were applied to arrive at the corrected count rates for all the gamma rays. Present study has shown that the estimation of ~1 g of 239Pu in a waste drum can be carried out in the presence of 137Cs up to an activity level of 20 mCi.

Restricted access

Introduction Uranium–plutonium mixed carbides have been successfully irradiated up to a burn-up of 159 GWd/t in the Fast Breeder Test Reactor (FBTR) in Kalpakkam for the first time in the world. FBTR uses a high plutonium

Restricted access

Abstract  

Knowledge of the oxidation state distribution of plutonium in natural waters is necessary in modeling its behavior in environmental systems. The redox speciation of plutonium is complicated by such effects as hydrolysis, complexation, disproportionation, solubility, and redox interchange reactions. The insolubility of Pu(OH)4 is often the limiting factor of the net solubility of plutonium in oxic natural waters where Pu(V)O 2 + is the most stable oxidation state. Perturbations to the oxidation state speciation due to the complexation chemistry of the different oxidation states of plutonium and to the insolubility of plutonium(IV) in neutral aquatic systems are discussed. The merits and limitations of some chemical separation techniques used to study redox speciation of plutonium are presented, and recommendations made for obtaining reliable oxidation state distribution data.

Restricted access

Abstract  

A method for ascertaining equilibrium valence state distributions of plutonium in acid solutions as a function of the plutonium oxidation number and the solution acidity is illustrated with an example. The method may be more practical for manual use than methods based upon polynomial equations.

Restricted access

Abstract  

Sediment core samples were collected from Hiroshima Bay in the Seto Inland Sea, western Northwest Pacific Ocean, and their 239+240Pu activities and 240Pu/239Pu atom ratios were determined by sector field ICP-MS. The activities of 239+240Pu ranged from 0.556 ± 0.025 to 0.745 ± 0.023 mBq/g. The atom ratios of 240Pu/239Pu were almost constant within the whole depth; the average value was 0.227 ± 0.014. This atom ratio was significantly higher than the mean global fallout ratio of 0.18, proving the presence of close-in fallout Pu that originated from the Pacific Proving Ground (PPG). The water masses exchanges between the Kuroshio Current and the Seto Inland Sea brought the PPG source Pu to this area, then Pu was extensively scavenged into sediment particles supplied by the rivers around the bay. The relative contributions of the global fallout Pu and the PPG close-in fallout Pu were evaluated by the two end-member mixing model. The contribution of the PPG close-in fallout was 38–41% of the total Pu in sediment. The remaining 59–62% was attributed to direct global fallout and the land-origin Pu transported by the rivers around the Hiroshima Bay.

Restricted access

Abstract  

Methods of monitoring low plutonium concentration in the inner and outer atmosphere are analyzed and compared. It is shown that monitors based on the gross alpha counting of air filters are not sensitive enough to measure reliably plutonium activities below 1 MPC. A spectrometric discontinuously operating monitor using a gridded ionization chamber and a membrane filter having 70 cm2 active area is described. Plutonium activities of the order of 0.01 MPC /1 mBq.m–3/ can be measured by the spectrometer at 1 h sampling and 1 h counting time.

Restricted access

Abstract  

Two reasons for understanding the increasing fraction of pentavalent plutonium with rising temperature in dilute acid are presented. The reasons make the results of calculations easier to understand.

Restricted access

Abstract  

Plutonium in nanogram quantities was isolated from uranium targets irradiated with charged particles. High decontamination was achieved using a method that combines anion exchange with extraction chromatography in tributyl phosphate/hydrochlorid acid solution system.

Restricted access

Abstract  

In the potentiometric titration of plutonium(III), it has been customary to take the equivalence point as the inflection point on a plot of potential vs. volume of titrant.1 That the stoichiometric end point corresponds to the inflection point does not seem to have been theoretically demonstrated, however. The purpose of this letter is to suggest that these points may not correspond in the potentiometric titration of plutonium(III).

Restricted access