Author: Armen R. KazanjianPublisher:
ISBN:
Category :
Languages : en
Pages : 8
Book Description
Dissolution of Plutonium Oxide in Nitric Acid at High Hydrofluoric Acid Concentrations
Author: Armen R. KazanjianDissolution of Plutonium Oxide in Nitric Acid at High Hydrofluoric Acid Concentrations
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
The dissolution of plutonium dioxide in nitirc acid (HNO3) at high hydrofluoric acid (HF) concentrations has been investigated. Dissolution rate curves were obtained using 12M HNO3 and HF at concentrations varying from 0.05 to 1.0 molar. The dissolution rate increased with HF concentration up to 0.2M and then decreased at higher concentrations. There was very little plutonium dissolved at 0.7 and 1.0M HF because of the formation of insoluble PuF4. Various oxidizing agents were added to 12M HNO3-1M HF dissolvent to oxidize Pu(IV) to Pu(VI) and prevent the formation of PuF4. Ceric (Ce(IV)) and silver (Ag(II)) ions were the most effective in dissolving PuO2. Although these two oxidants greatly increased the dissolution rate, the rates were not as rapid as those obtained with 12M HNO3-0.2M HF.
Dissolution of High-density UO2, PuO2, and UO2-PuO2 Pellets in Inorganic Acids
Author: Armando L. UriartePublisher:
ISBN:
Category : Inorganic acids
Languages : en
Pages : 90
Book Description
Processing of Non-PFP Plutonium Oxide in Hanford Plants
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
Processing of non-irradiated plutonium oxide, PuO2, scrap for recovery of plutonium values occurred routinely at Hanford's Plutonium Finishing Plant (PFP) in glovebox line operations. Plutonium oxide is difficult to dissolve, particularly if it has been high-fired; i.e., calcined to temperatures above about 400°C and much of it was. Dissolution of the PuO2 in the scrap typically was performed in PFP's Miscellaneous Treatment line using nitric acid (HNO3) containing some source of fluoride ion, F-, such as hydrofluoric acid (HF), sodium fluoride (NaF), or calcium fluoride (CaF2). The HNO3 concentration generally was 6 M or higher whereas the fluoride concentration was 0̃.5 M or lower. At higher fluoride concentrations, plutonium fluoride (PuF4) would precipitate, thus limiting the plutonium dissolution. Some plutonium-bearing scrap also contained PuF4 and thus required no added fluoride. Once the plutonium scrap was dissolved, the excess fluoride was complexed with aluminum ion, Al3+, added as aluminum nitrate, Al(NO3)3-9H2O, to limit collateral damage to the process equipment by the corrosive fluoride. Aluminum nitrate also was added in low quantities in processing PuF4.
Acid Dissolution Method for the Analysis of Plutonium in Soil
Author: E. L. WhittakerPublisher:
ISBN:
Category : Analytical chemistry
Languages : en
Pages : 72
Book Description
Separation and Determination of Plutonium in Plutonium-uranium Fuel Elements
Author: C. E. PietriPublisher:
ISBN:
Category : Nuclear fuel elements
Languages : en
Pages : 16
Book Description
Plutonium Dissolution Process
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
A two-step process for dissolving plutonium metal, which two steps can be carried out sequentially or simultaneously. Plutonium metal is exposed to a first mixture containing approximately 1.0M-1.67M sulfamic acid and 0.0025M-0.1M fluoride, the mixture having been heated to a temperature between 45.degree. C. and 70.degree. C. The mixture will dissolve a first portion of the plutonium metal but leave a portion of the plutonium in an oxide residue. Then, a mineral acid and additional fluoride are added to dissolve the residue. Alteratively, nitric acid in a concentration between approximately 0.05M and 0.067M is added to the first mixture to dissolve the residue as it is produced. Hydrogen released during the dissolution process is diluted with nitrogen.
Plutonium Dioxide Dissolution in Nitric/hydrofluoric Acid Mixtures
Author: DISSOLUTION OF PLUTONIUM METAL USING NITRIC ACID SOLUTIONS CONTAINING POTASSIUM FLUORIDE.
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
The deinventory and deactivation of the Savannah River Site's (SRS's) FB-Line facility required the disposition of approximately 2000 items from the facility's vaults. Plutonium (Pu) scraps and residues which do not meet criteria for conversion to a mixed oxide fuel will be dissolved and the solution stored for subsequent disposition. Some of the items scheduled for dissolution are composite materials containing Pu and tantalum (Ta) metals. The preferred approach for handling this material is to dissolve the Pu metal, rinse the Ta metal with water to remove residual acid, and burn the Ta metal. The use of a 4 M nitric acid (HNO3) solution containing 0.2 M potassium fluoride (KF) was initially recommended for the dissolution of approximately 500 g of Pu metal. However, prior to the use of the flowsheet in the SRS facility, a new processing plan was proposed in which the feed to the dissolver could contain up to 1250 g of Pu metal. To evaluate the use of a larger batch size and subsequent issues associated with the precipitation of plutonium-containing solids from the dissolving solution, scaled experiments were performed using Pu metal and samples of the composite material. In the initial experiment, incomplete dissolution of a Pu metal sample demonstrated that a 1250 g batch size was not feasible in the HB-Line dissolver. Approximately 45% of the Pu was solubilized in 4 h. The remaining Pu metal was converted to plutonium oxide (PuO2). Based on this work, the dissolution of 500 g of Pu metal using a 4-6 h cycle time was recommended for the HB-Line facility. Three dissolution experiments were subsequently performed using samples of the Pu/Ta composite material to demonstrate conditions which reduced the risk of precipitating a double fluoride salt containing Pu and K from the dissolving solution. In these experiments, the KF concentration was reduced from 0.2 M to either 0.15 or 0.175 M. With the use of 4 M HNO3 and a reduction in the KF concentration to 0.175 M, the dissolution of 300 g of Pu metal is expected to be essentially complete in 6 h. The dissolution of larger batch sizes would result in the formation of PuO2 solids. Incomplete dissolution of the PuO2 formed from the metal is not a solubility limitation, but can be attributed to a combination of reduced acidity and complexation of fluoride which slows the dissolution kinetics and effectively limits the mass of Pu dissolved.
Method for Dissolving Plutonium Dioxide
Author: Publisher:
ISBN:
Category :
Languages : en
Pages :
Book Description
A method for dissolving plutonium dioxide comprises adding silver ions to a nitric acid-hydrofluoric acid solution to significantly speed up dissolution of difficultly soluble plutonium dioxide.