US3890244A
Expired / Lapsed
US
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Recovery of technetium from nuclear fuel wastes
Assignee: PPG Industries Inc
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Filing: 1972-11-24
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Granted: 1975-06-17
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Expires: 1992-11-24
Abstract
Abstract Technetium is removed from aqueous, acidic waste solutions thereof. The acidic waste solution is mixed with a flocculant, e.g., an alkaline earth metal hydroxide or oxide, to precipitate certain fission products, e.g., palladium, rhodium and ruthenium, contained in the acidic waste solution. Technetium remains in solution and in the resulting supernatant alkaline aqueous phase. The supernatant alkaline aqueous phase is made acidic and electrolyzed in an electrolytic cell under controlled cathodic potential conditions to deposit technetium on the cathode. Elemental technetium is removed from the cathode. Technetium is separated from other plated fission product metals by extraction from an alkaline solution with an organic extractant, such as pyridine, having affinity for technetium. Technetium is separated from the organic extractant by steam distillation and the resulting aqueous phase treated with ammoniacal reagent to precipitate technetium as ammonium pertechnetate. The precipitate from the flocculation step is removed to an interim storage vessel from whence it can be returned to the nuclear fuel processor for disposal. In a further embodiment, the precipitate is acidified to form an aqueous acidic solution of fission product metal values and the solution electrolyzed in an electrolytic cell under controlled cathodic potential conditions and at a potential sufficiently negative to plate out from the solution those fission product metals desired. The metal deposit is stripped from the cathode and stored until its radioactivity has diminished. The metal depleted cell liquor is returned to the nuclear fuel processor.
Inventors
- 👤 William W Carlin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 13:00
CPC Classifications
G; G21; G21F; G21F9/00; G21F9/007
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
134 words
A PROCESS FOR SEPARATING TECHNETIUM VALUES FROM AQUEOUS ACIDIC SOLUTION CONTAINING SAID METAL VALUES AND OTHER FISSION PRODUCT METAL VALUES, WHICH COMPRISES MIXING WITH SAID ACIDIC SOLUTION ALKALINE FLOCCULATING REAGENT SELECTED FROM ALKALINE EARTH METAL OXIDES AND HYDROXIDES IN AMOUNTS SUFFICIENT TO RAISE THE PH OF THE SOLUTION TO BETWEEN ABOUT 9 AND ABOUT 12 AND THEREBY FORM A PRECIPITATE CONTAINING FISSION PRODUCT METAL VALUES AND A SUPERNATANT PHASE CONTANING TECHNETIUM VALUES, SEPARATING THE SUPERNATANT FROM THE PRECIPITATE, ACIDIFYING THE SUPERNATANT WITH MINERAL ACID TO AN ACID CONCENTRATION OF NOT MORE THAN ABOUT 1 MOLAR, ELECTROLYZING ACIDIFIED SUPERNATANT IN AN ELECTROLYTIC CELL UNDER CONTROLLED CATHODIC POTENTIAL CONDITIONS AND AT A POTENTIAL SUFFICIENT TO DEPOSIT TECHNETIUM ON THE CATHODE, REMOVING TECHNETIUM DEPLETED SUPERNATANT FROM THE ELECTROLYTIC CELL AND REMOVING ELEMENTAL TECHNETIUM DEPOSITS FROM THE CATHODE.
Claim 2
Dependent Claim
134 words
A PROCESS FOR SEPARATING TECHNETIUM VALUES FROM AQUEOUS ACIDIC SOLUTION CONTAINING SAID METAL VALUES AND OTHER FISSION PRODUCT METAL VALUES, WHICH COMPRISES MIXING WITH SAID ACIDIC SOLUTION ALKALINE FLOCCULATING REAGENT SELECTED FROM ALKALINE EARTH METAL OXIDES AND HYDROXIDES IN AMOUNTS SUFFICIENT TO RAISE THE PH OF THE SOLUTION TO BETWEEN ABOUT 9 AND ABOUT 12 AND THEREBY FORM A PRECIPITATE CONTAINING FISSION PRODUCT METAL VALUES AND A SUPERNATANT PHASE CONTANING TECHNETIUM VALUES, SEPARATING THE SUPERNATANT FROM THE PRECIPITATE, ACIDIFYING THE SUPERNATANT WITH MINERAL ACID TO AN ACID CONCENTRATION OF NOT MORE THAN ABOUT 1 MOLAR, ELECTROLYZING ACIDIFIED SUPERNATANT IN AN ELECTROLYTIC CELL UNDER CONTROLLED CATHODIC POTENTIAL CONDITIONS AND AT A POTENTIAL SUFFICIENT TO DEPOSIT TECHNETIUM ON THE CATHODE, REMOVING TECHNETIUM DEPLETED SUPERNATANT FROM THE ELECTROLYTIC CELL AND REMOVING ELEMENTAL TECHNETIUM DEPOSITS FROM THE CATHODE.
Claim 3
Dependent Claim
16 words
The process of claim 1 wherein the acidic waste solution is a Purex acid waste stream.
Claim 4
Dependent Claim
24 words
The process of claim 1 wherein the waste solution is filtered before being mixed with the alkaline flocculating reagent to remove undissolved rhodium therefrom.
Claim 5
Dependent Claim
19 words
The process of claim 1 wherein the alkaline flocculating reagent is an oxide or hydroxide of magnesium or calcium.
Claim 6
Dependent Claim
26 words
The process of claim 1 wherein the pH of the waste solution is raised to from about 9 to about 11 with the alkaline flocculating reagent.
Claim 7
Dependent Claim
16 words
The process of claim 1 wherein the supernatant phase is acidified with nitric or sulfuric acid.
Claim 8
Dependent Claim
21 words
The process of claim 1 wherein the acidified supernatant has an acid concentration of from 0.25 molar to about 1 molar.
Claim 9
Dependent Claim
33 words
The process of claim 1 wherein the acidified supernatant is electrolyzed at a controlled cathode potential of from about -0.3 to about -0.5 volts with reference to a standard silver/silver chloride reference electrode.
Claim 10
Dependent Claim
60 words
The process of claim 1 wherein technetium metal deposited on the cathode is dissolved in strong mineral acid to form an acid solution of technetium values, the acid solution is made alkaline with alkaline reagnet, technetium values are extracted from the alkaline solution with an organic solvent having affinity for technetium and technetium values are separated from the organic solvent.
Claim 11
Dependent Claim
16 words
The process of claim 9 wherein the organic solvent is pyridine or dimethyl substituted pyridine derivatives.
Claim 12
Dependent Claim
39 words
The process of claim 9 wherein the organic solvent containing extracted technetium is steam distilled to provide an aqueous solution containing technetium values and ammoniacal reagnet is added to the aqueous solution in amounts sufficient to form ammonium pertechnetate.
Claim 13
Dependent Claim
60 words
The process of claim 1 wherein the precipitate is dissolved in mineral acid to form an acidic solution of fission product metal values having an acid concentration of less than 4 molar and the acidic solution electrolyzed in an electrolytic cell under controlled cathodic potential conditions and at a potential at which palladium and rhodium are deposited on the cathode.
Claim 14
Dependent Claim
30 words
The process of claim 12 wherein the acidic solution is electrolyzed at a controlled cathode potential of at least -0.1 volts with reference to a standard silver/silver chloride reference electrode.
Claim 15
Dependent Claim
18 words
The process of claim 13 wherein the controlled cathode potential is from about -0.1 to about -0.15 volts.
Claim 16
Dependent Claim
144 words
A process for separating technetium values from aqueous acidic solution containing said metal values and other fission product metal values, said aqueous acidic solution being obtained from the processing of nuclear fuel elements, which comprises mixing with said acidic solution alkaline flocculating agent selected from the oxides and hydroxides of calcium and magnesium to raise the pH of the solution to between 9 and 11 and thereby form a precipitate containing fission product metal values and a supernatant phase containing technetium values, separating the supernatant from the precipitate, acidifying the supernatant with mineral acid to an acid concentration of less than about 1 molar, electrolyzing the acidified supernatant in an electrolytic cell under controlled cathodic potential conditions and at a potential sufficient to deposit technetium on the cathode, removing technetium depleted supernatant from the electrolytic cell and removing elemental technetium deposits from the cathode.
Claim 17
Dependent Claim
144 words
A process for separating technetium values from aqueous acidic solution containing said metal values and other fission product metal values, said aqueous acidic solution being obtained from the processing of nuclear fuel elements, which comprises mixing with said acidic solution alkaline flocculating agent selected from the oxides and hydroxides of calcium and magnesium to raise the pH of the solution to between 9 and 11 and thereby form a precipitate containing fission product metal values and a supernatant phase containing technetium values, separating the supernatant from the precipitate, acidifying the supernatant with mineral acid to an acid concentration of less than about 1 molar, electrolyzing the acidified supernatant in an electrolytic cell under controlled cathodic potential conditions and at a potential sufficient to deposit technetium on the cathode, removing technetium depleted supernatant from the electrolytic cell and removing elemental technetium deposits from the cathode.
Claim 18
Dependent Claim
60 words
The process of claim 15 wherein the precipitate is dissolved in mineral acid to form an acidic solution of fission product metal values having an acid concentration of less than 4 molar and the acidic solution electrolyzed in an electrolytic cell under controlled cathodic potential conditions and at a potential at which palladium and rhodium are deposited on the cathode.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-06-16 | 1978-12-16 | 1979-06-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-16 | 1982-12-16 | 1983-06-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-16 | 1986-12-16 | 1987-06-17 | $7700.00 | Window Closed / Lapsed |