GB1600211A - Processes for the treatment of radioactive effluents - Google Patents
Processes for the treatment of radioactive effluents Download PDFInfo
- Publication number
- GB1600211A GB1600211A GB1874878A GB1874878A GB1600211A GB 1600211 A GB1600211 A GB 1600211A GB 1874878 A GB1874878 A GB 1874878A GB 1874878 A GB1874878 A GB 1874878A GB 1600211 A GB1600211 A GB 1600211A
- Authority
- GB
- United Kingdom
- Prior art keywords
- boric acid
- radio
- distilled
- residue
- isotopes
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
- 238000000034 method Methods 0.000 title claims description 23
- 230000002285 radioactive effect Effects 0.000 title claims description 17
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 60
- KGBXLFKZBHKPEV-UHFFFAOYSA-N boric acid Chemical compound OB(O)O KGBXLFKZBHKPEV-UHFFFAOYSA-N 0.000 claims description 47
- 239000004327 boric acid Substances 0.000 claims description 47
- 150000002148 esters Chemical class 0.000 claims description 25
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 24
- 239000001117 sulphuric acid Substances 0.000 claims description 24
- 235000011149 sulphuric acid Nutrition 0.000 claims description 24
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 22
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 18
- 239000002244 precipitate Substances 0.000 claims description 16
- 229910052787 antimony Inorganic materials 0.000 claims description 14
- 239000012141 concentrate Substances 0.000 claims description 12
- 230000000694 effects Effects 0.000 claims description 9
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 claims description 8
- 238000006243 chemical reaction Methods 0.000 claims description 8
- 235000011121 sodium hydroxide Nutrition 0.000 claims description 6
- 238000001816 cooling Methods 0.000 claims description 5
- PWHULOQIROXLJO-UHFFFAOYSA-N Manganese Chemical compound [Mn] PWHULOQIROXLJO-UHFFFAOYSA-N 0.000 claims description 4
- PMZURENOXWZQFD-UHFFFAOYSA-L Sodium Sulfate Chemical compound [Na+].[Na+].[O-]S([O-])(=O)=O PMZURENOXWZQFD-UHFFFAOYSA-L 0.000 claims description 4
- 229910052792 caesium Inorganic materials 0.000 claims description 4
- TVFDJXOCXUVLDH-UHFFFAOYSA-N caesium atom Chemical compound [Cs] TVFDJXOCXUVLDH-UHFFFAOYSA-N 0.000 claims description 4
- 238000009388 chemical precipitation Methods 0.000 claims description 4
- 229910017052 cobalt Inorganic materials 0.000 claims description 4
- 239000010941 cobalt Substances 0.000 claims description 4
- GUTLYIVDDKVIGB-UHFFFAOYSA-N cobalt atom Chemical compound [Co] GUTLYIVDDKVIGB-UHFFFAOYSA-N 0.000 claims description 4
- 238000001704 evaporation Methods 0.000 claims description 4
- 229910052748 manganese Inorganic materials 0.000 claims description 4
- 239000011572 manganese Substances 0.000 claims description 4
- 238000010908 decantation Methods 0.000 claims description 3
- 238000000354 decomposition reaction Methods 0.000 claims description 3
- 230000001376 precipitating effect Effects 0.000 claims description 3
- 238000003825 pressing Methods 0.000 claims description 3
- 239000003153 chemical reaction reagent Substances 0.000 claims description 2
- 238000001914 filtration Methods 0.000 claims description 2
- 238000001556 precipitation Methods 0.000 claims description 2
- 238000004064 recycling Methods 0.000 claims description 2
- 229910052938 sodium sulfate Inorganic materials 0.000 claims description 2
- 235000011152 sodium sulphate Nutrition 0.000 claims description 2
- WBQSJYNAUANADO-UHFFFAOYSA-N sodium;dihydrogen borate Chemical compound [Na+].OB(O)[O-] WBQSJYNAUANADO-UHFFFAOYSA-N 0.000 claims description 2
- 150000003839 salts Chemical class 0.000 description 2
- 238000005202 decontamination Methods 0.000 description 1
- 230000003588 decontaminative effect Effects 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 230000007062 hydrolysis Effects 0.000 description 1
- 238000006460 hydrolysis reaction Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000012857 radioactive material Substances 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
- G21F—PROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
- G21F9/00—Treating radioactively contaminated material; Decontamination arrangements therefor
- G21F9/04—Treating liquids
- G21F9/06—Processing
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- General Engineering & Computer Science (AREA)
- High Energy & Nuclear Physics (AREA)
- Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
- Heat Treatment Of Water, Waste Water Or Sewage (AREA)
- Removal Of Specific Substances (AREA)
Description
(54) IMPROVEMENTS IN OR RELATING TO PROCESSES FOR THE
TREATMENT OF RADIO-ACTIVE EFFLUENTS
(71) We, RHEINIsCH-WEsTFALIsCHES ELEKTRIZITATSWERK AKTIENGESELLSCHAFT, of Kruppstrasse 5, D-4300 Essen 1, Federal
Republic of Germany, ajoint stock company organized under the laws of Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to processes for the treatment of effluents containing boric acid, radio-antimony and other radio-isotopes, with particular reference, for example, to boiler concentrates from nuclear power plants.
Known effluents of this nature have hitherto been disposed of as a whole, i.e., without treatment. However, the disposal costs have substantially increased in recent years. Further substantial inflation is probable in the future. Moreover, concern for environmental conservation will probably give rise to greater opposition to the transporting of radio-active liquids in large quantities for disposal purposes.
Various means are known in the art for reducing the volume of radio-active material for disposal and thereby reducing the disposal costs, with reference to radio-active effluents in general; for example, radio-active effluents are already evaporated down, and again the radio-isotopes can be precipitated from the effluent (as described in German
Patent Specification No. 1767999). However, the effluents originally referred to do not respond satifactorily to evaporation treatment, since all the other inactive salts in the effluents must still be disposed of along with the radio-isotopes.Attempts to isolate the radio-isotopes from such effluents by chemical precipitation have failed because the degree of decontamination remains too low, particularly with reference to the radioantimony present; the chemical precipitation of certain radio-isotopes is affected by interference from the salts and other radioisotopes also present.
It is also known (for example, see ABC
Chemie, vol. 1, A-K, 2nd revised edition,
Verlag Harri Deutsch, Frankfurt/Main and
Zurich, 1975, page 198) that boric acid can be converted to its trimethyl ester by methanol in the presence of concentrated sulphuric acid, and that the trimethyl ester of boric acid can be converted back to boric acid and methanol by hydrolysis. This knowledge has not hitherto been applied to the problems of treating the effluents originally referred to.
The object of the invention is to provide an economical treatment process of the type originally referred to, whereby the radioisotopes are concentrated into a small volume of material, compared with the initial volume of effluent, and can therefore be disposed of at a reasonable cost.
According to the invention, this object is achieved by evaporating the effluent substantially to dryness, treating the residue with concentrated sulphuric acid and, after cooling, with methanol, distilling off the resulting trimethyl ester of boric acid, storing the residue until the antimony activity has been dissipated, precipitating the radio-isotopes chemically from the stored residue, and isolating the radio-active precipitate.
In other words, the first stage of the treatment process of the invention is the removal of boric acid from the effluent in the form of its trimethyl ester. The residue from the first stage, containing the radio-isotopes, is stored in the second stage until the antimony activity has been dissipated, since it is impossible in practice to precipitate the radio-antimony by chemical means along with the other radio-isotopes. Residue storage is no problem, since antimony (Sb'24) has a half-life of only 60.3 days and the antimony activity dies down to about 1.6 and 0.02% after 1 and 2 years respectively. The next, third, stage of the process is the chemical precipitation of the further radioisotopes.
This precipitation is surprisingly close to quantitative, since the radio-antimony concentration is more or less down to zero and the concentrations of other radio-isotopes are high. The isolated radio-active precipitate obtained by the process of the invention occupies at the most 1% of the original volume of effluent, and the disposal costs are no longer substantial.
The advantages accruing from the invention are to be seen substantially in the low cost of the treatment.
Various possibilities are open for further improvement within the scope of the invention. If the effluent contains large amounts of caustic soda as well as boric acid, which can be the case with boiler concentrates encountered in nuclear power plants, the boric acid will take the form of sodium dihydrogen borate; the residue from the first processing stage in this case will consist substantially of sulphuric acid, sodium sulphate, water and radio-isotopes. However, if the effluent is free from caustic soda, the process of the invention can be modified very advantageously. Water remaining after distilling off the trimethyl ester of boric acid is preferably itself distilled off, and before the residue is put into storage it is recycled at least once, as concentrated sulphuric acid for the treatment of further effluent, thereby additionally enriching it with radio-isotopes.In this case, the residue after distilling off the water of reaction from the boric acid/methanol reaction consists entirely of concentrated sulphuric acid and radio-isotopes. It is for practical purposes an impure concentrated sulphuric acid and it can be significantly enriched with radio-isotopes by recycling repeatedly, as convenient. These features of the invention not only reduce the sulphuric acid consumption in the first processing stage but also significantly reduce the volume of radioactive precipitate. A further preferred embodiment of the invention is that the distilled trimethyl ester of boric acid is decomposed with water and that the resulting methanol is distilled off and recycled to form the trimethyl ester of boric acid during the treatment of a further batch of effluent.
The methanol cycle can be made almost lossfree in this way, thereby still further and substantially reducing the reagent costs for the first processing stage. The decomposition of the distilled trimethyl ester of boric acid with water liberates crystalline boric acid, which can be recovered by centrifuging or pressing, for subsequent use; the precipitate is surprisingly of analytical purity. The radioactive precipitate for final disposal is preferably isolated from the stored residue by decantation, filtration or centrifuging.
The invention will now be described in more detail with reference to a typical embodiment thereof:
Boiler concentrate (lton) from a nuclear power plant had a boric acid content of about 10% by weight and a specific gammaactivity of 0.26 Ci/ton, about 70% emanating from Sb'24 and the remainder substantially from radio-isotopes of caesium, cobalt and manganese. The boiler concentrate was evaporated down substantially to dryness and treated with 16 kg of concentrated sulphuric acid followed, after cooling, by 155 kg of methanol, thereby forming the trimethyl ester of boric acid and water of reaction.
The trimethyl ester of boric acid was distilled off at a temperature of 68.75 C, into a water condenser. The water was then distilled off also. The residue (16 kg) was used as concentrated sulphuric acid to treat a further batch of boiler concentrate in the same way, and was in fact recycled until the residue had been enriched with radio-isotopes to a specific gamma-activity of 100
Ci/ton. The enriched residue was bled from the sulphuric acid cycle, simultaneously replacing it with fresh concentrated sulphuric acid, and stored until its antimony activity had died down to 0.02% of its original level.
The radio-isotopes of caesium, cobalt and manganese were then precipitated chemically, the radio-active precipitate being isolated and eventually disposed of. The volume of precipitate was no more than 1% of the original volume treated. The trimethyl ester of boric acid, distilled into the water condenser, decomposed therein to methanol and boric acid. The methanol was distilled off and recycled for the boric acid/methanol reaction in a subsequent batch of boiler concentrate for treatment. The crystalline boric acid was recovered by centrifuging; it was 99.9% pure and could therefore be returned directly to a primary system of a nuclear power plant.
WHAT WE CLAIM IS:
1. A process for the treatment of effluents containing boric acid, radio-antimony and other radio-isotopes, the process comprising evaporating the effluent substantially to dryness, treatment the residue with concentrated sulphuric acid and, after cooling, with methanol, distilling off the resulting trimethyl ester of boric acid, storing the residue until the antimony activity has been dissipated, precipitating the radio-isotopes chemically from the stored residue, and isolating the radio-active precipitate.
2. A process as in Claim 1, wherein when the effluent contains no caustic soda water remaining after distilling off the trimethyl ester of boric acid is itself distilled off, and before the residue is put into storage it is recycled at least once, as concentrated sulphuric acid for the treatment of further
**WARNING** end of DESC field may overlap start of CLMS **.
Claims (7)
1. A process for the treatment of effluents containing boric acid, radio-antimony and other radio-isotopes, the process comprising evaporating the effluent substantially to dryness, treatment the residue with concentrated sulphuric acid and, after cooling, with methanol, distilling off the resulting trimethyl ester of boric acid, storing the residue until the antimony activity has been dissipated, precipitating the radio-isotopes chemically from the stored residue, and isolating the radio-active precipitate.
2. A process as in Claim 1, wherein when the effluent contains no caustic soda water remaining after distilling off the trimethyl ester of boric acid is itself distilled off, and before the residue is put into storage it is recycled at least once, as concentrated sulphuric acid for the treatment of further
effluent, thereby enriching it with radioisotopes.
3. A process as in Claim 1 or Claim 2, wherein the distilled trimethyl ester of boric acid is decomposed with water, and the resulting methanol is distilled off and recycled to form the trimethyl ester of boric acid during the treatment of a further batch of effluent.
4. A process as in Claim 3, wherein the crystalline boric acid formed during the decomposition with water of the distilled trimethyl ester of boric acid is recovered and if necessary dried.
5. A process as in Claim 4, wherein the crystalline boric acid is isolated by centrifuging or pressing.
6. A process as in any one of Claims 1 to 5, wherein the radio-active precipitate is isolated by decantation, filtation or centrifuging.
7. A process for the treatment of boiler concentrate from a nuclear power plant substantially as hereinbefore described.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19772723025 DE2723025C3 (en) | 1977-05-21 | 1977-05-21 | Process for treating wastewater containing boric acid, radioactive antimony and other radioactive nuclides |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1600211A true GB1600211A (en) | 1981-10-14 |
Family
ID=6009561
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1874878A Expired GB1600211A (en) | 1977-05-21 | 1978-05-10 | Processes for the treatment of radioactive effluents |
Country Status (3)
| Country | Link |
|---|---|
| DE (1) | DE2723025C3 (en) |
| FR (1) | FR2391533A1 (en) |
| GB (1) | GB1600211A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4540512A (en) * | 1983-04-06 | 1985-09-10 | Westinghouse Electric Corp. | Recovery of boric acid from nuclear waste |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2459536A1 (en) * | 1979-06-14 | 1981-01-09 | Commissariat Energie Atomique | PROCESS FOR TREATING DECONTAMINATION EFFLUENTS, IN PARTICULAR NUCLEAR REACTOR COMPONENTS AND DEVICE FOR IMPLEMENTING SAID METHOD |
| DE2950601A1 (en) * | 1979-12-15 | 1981-06-19 | Rainer Dr. 6843 Biblis Ambros | METHOD FOR THE RECOVERY OF BORSAEUR FROM A WASTE WATER CONCENTRATE OF A NUCLEAR POWER PLANT |
| HU195967B (en) * | 1985-05-13 | 1988-08-29 | Tatabanyai Szenbanyak | Process for recovering boric acid solution, reusable in atomic power station, from radioactive solutions of atomic power station |
| DE3638053A1 (en) * | 1985-05-25 | 1988-05-19 | Licentia Gmbh | Electrophotographic recording material |
| DE3600358A1 (en) * | 1986-01-09 | 1987-07-16 | Mtt Metalltrenntechnik Fuer Nu | Method and device for cleaning water-containing machinery oil from nuclear energy installations |
| DD293219A5 (en) * | 1988-12-14 | 1991-08-22 | ������@������������k�� | PROCESS FOR PREPARING BORONIC COMPOUNDS AND RADIONUCLIDE-CONTAINING WASTE WATER |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE838533A (en) * | 1976-02-13 | 1976-05-28 | PROCESS FOR DRYING SOLUTIONS CONTAINING BORIC ACID |
-
1977
- 1977-05-21 DE DE19772723025 patent/DE2723025C3/en not_active Expired
-
1978
- 1978-05-10 GB GB1874878A patent/GB1600211A/en not_active Expired
- 1978-05-19 FR FR7814914A patent/FR2391533A1/en active Granted
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4540512A (en) * | 1983-04-06 | 1985-09-10 | Westinghouse Electric Corp. | Recovery of boric acid from nuclear waste |
Also Published As
| Publication number | Publication date |
|---|---|
| DE2723025C3 (en) | 1980-03-13 |
| FR2391533A1 (en) | 1978-12-15 |
| FR2391533B1 (en) | 1980-06-20 |
| DE2723025A1 (en) | 1978-11-23 |
| DE2723025B2 (en) | 1979-07-05 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PS | Patent sealed | ||
| PCNP | Patent ceased through non-payment of renewal fee |