US4725383A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for volume reduction and solidification of a radioactive sodium borate waste solution
Assignee: Ebara Corp
•
Filing: 1986-10-27
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Granted: 1988-02-16
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Expires: 2006-10-27
Abstract
Abstract A process is disclosed for volume reduction and solidification of a radioactive waste solution mainly composed of sodium borate and discharged from a pressurized water reactor. The process comprises adding to said radioactive waste solution, ZnO or a mixture of ZnO with Al 2 O 3 and/or CaO, and then subjecting the resulting mixture to dehydration and melting to produce a vitrified solid solution. Said process is safe and reliable. A vitrified solid solution produced by said process is safe and stable.
Inventors
- 👤 Tadamasa Hayashi
- 👤 Toyoshi Mizushima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 22:56
CPC Classifications
C; C03; C03C; C03C1/00; C03C1/002; G; G21; G21F; G21F9/00; G21F9/28; G21F9/30; G21F9/301; G21F9/302; G21F9/305; Y; Y10; Y10S; Y10S159/00; Y10S159/12; Y10S422/00; Y10S422/903
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
194 words
A process for volume reduction and solidification of a radioactive waste solution of sodium borate disharged from a pressurized water reactor, which comprises (a) mixing the concentrate of a radioactive waste solution of sodium borate discharged from a pressurized water reactor at a pH of 9.6 or less and having a Na 2 O to B 2 O 3 molar ratio of 0.10 to 0.60, or the dried material of said concentrate, with a stabilizing agent in water composed mainly of an inorganic zinc compound, so that, when a mixture of an evaporation residue of said waste solution and said stabilizing agent has been subjected to melting to form a vitrified solid solution, the content of ZnO in the vitrified solid solution becomes 10 to 40 mole %, and then (b) subjecting the resulting mixture to at least partial dehydration and melting with heating by a heating method employing irradiation with microwaves of 915±50 to 2450±50 MHz to produce a vitrified solid solution composed mainly of Na 2 O-B 2 O 3 -ZnO. wherein said vitrified solid solution does not include Si0 2 as a component, except for its presence as an incidental impurity.
Claim 2
Dependent Claim
194 words
A process for volume reduction and solidification of a radioactive waste solution of sodium borate disharged from a pressurized water reactor, which comprises (a) mixing the concentrate of a radioactive waste solution of sodium borate discharged from a pressurized water reactor at a pH of 9.6 or less and having a Na 2 O to B 2 O 3 molar ratio of 0.10 to 0.60, or the dried material of said concentrate, with a stabilizing agent in water composed mainly of an inorganic zinc compound, so that, when a mixture of an evaporation residue of said waste solution and said stabilizing agent has been subjected to melting to form a vitrified solid solution, the content of ZnO in the vitrified solid solution becomes 10 to 40 mole %, and then (b) subjecting the resulting mixture to at least partial dehydration and melting with heating by a heating method employing irradiation with microwaves of 915±50 to 2450±50 MHz to produce a vitrified solid solution composed mainly of Na 2 O-B 2 O 3 -ZnO. wherein said vitrified solid solution does not include Si0 2 as a component, except for its presence as an incidental impurity.
Claim 3
Dependent Claim
52 words
A process for volume reduction and solidification according to claim 1, wherein the concentrate of a radioactive waste solution of sodium borate or the dried material of the concentrate has a Na 2 O to B 2 O 3 molar ratio of 0.15 to 0.45 and a pH of 7.0 to 9.1.
Claim 4
Dependent Claim
62 words
A process for volume reduction and solidification according to claim 1 or 2, wherein the concentrate of a radiactive waste solution of sodium borate or the dried material of the concentrate is mixed with a stabilizing agent in water composed mainly of an inorganic zinc compound so that the ZnO content of the vitrified solid solution becomes 13 to 38 mole %.
Claim 5
Dependent Claim
33 words
A process for volume reduction and solidification according to claim 1, wherein the inorganic zinc compound is ZnO, ZnCO 3 , Zn(OH) 2 , Zn(NO 3 ) 2 , or a mixture thereof.
Claim 6
Dependent Claim
82 words
A process for volume reduction and solidification according to claim 1, wherein the stabilizing agent in water is composed of a zinc compound and Al 2 O 3 and is used in such a proportion that the ZnO content and the Al 2 O 3 content of the produced vitrified solid solution is 10 to 40 mole % and 3 to 10 mole %, respectively, and the total content of ZnO and Al 2 O 3 does not exceed 43 mole %.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-02-15 | 1991-08-17 | 1992-02-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-02-15 | 1995-08-17 | 1996-02-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-02-15 | 1999-08-17 | 2000-02-16 | $7700.00 | Window Closed / Lapsed |