CS268821B2 - Method of boric acid's reapplicable solutions recovery in atomic power stations - Google Patents

Description

(57) obtaining re-usable solutions of borltic acid from radioactive contaminated technological waste of nuclear power plants in nuclear power plants · from radioactive waters * from sedimentation waters and mixtures thereof * in which radioactive waste and solutions from · nuclear power storage and collection systems, after the removal of floating substances * processed in the device for the first inverted osmosis, whose membrane retains eolts of alkali and heavy metal ions * carrying radioactivity * at least 80% * while borltic acid to at most 30% * of both osmosis solutions obtained * namely, from a concentrate containing a major amount of radioactivity carriers * and from a permeate containing a major amount of boric acid and a portion of an alkaline nitrate * the ss permeate is further processed in a second inverted oemosis device * whose membrane retains alkaline nitrates of at least 90% * borltic acid, but not more than 40% * of this blunt concentrate returned to the first inverted oemosis * permeate is passed through a vessel with macroporous strongly alkaline anion exchange resin arranged as a series of at least two • Columns * purified boreel cyeeline solution * containing less than 1/1000% alkaline nitrates * is fed back to eyetine boric acid treatment at atomic power plant and first stage concentrate * if its obeah cyeeline borate is less than 1500 sg / 1 * to radioactive waste treatment ·

С8 268821 В2

The invention also relates to a process for the regeneration in atomic power plants of reusable boric acid solutions from radioactive contaminated process solutions from wastewater from the decontamination waters of ethnoel power plants or from mixtures of the abovementioned effluents and also from the method of reducing radii of radioactively contaminated pollutants. to process one of the fundamental problems of ethno-electric power plants is safe and economically safe to deposit waste materials and radioactive waste materials · Above all, it is important to ensure that the volume to deposit certain harmful substances is small. »That the maximum permissible levels are prescribed for the radioactivity of certain substances» which may not exceed the limit values • redloctivity limits are necessary for safety reasons »concentration the boundaries of the meaning in that the material in which the harmful substances are introduced is not damaged »Therefore, the development of the process does not lead to any reduction in the volume of the deposited substances by taking into account the above-mentioned requirements» in terms of depositing undesirable substances ·

For operation under pressure of maintained water rooks - pressurized water reactor eo uses aqueous solutions of boric acid · Boric acid finishes into aqueous effluents with a mixture of nitric ions and olefinic metal ions with radioactive ions originating from corrosive processes · This often leads to significant loss of boric acid keeline »When finishing the shots, a certain concentration of boric acid keel can be exceeded» because too high a boric acid killer content damages the incorporation of the substances used · Regoneration of boric acid keel is therefore dual purpose » Its losses »both simplify the problem of depositing ·

Numerous ways have been elaborated to solve this task. According to German Patent Opposition No. 2 723 025, according to Swiss Patent Specification No. 553 148, kyeoline boric oetorifikujo othanole · »the ester is removed by distillation o again by conversion of acid ·

The method of Siemens has been described by Haitmann in "Aufberoitungotechnik", 1971/5, pp. 281 to 284. According to this method, boric acid leaves roogovot with sodium hydroxide to form metoborate, which crystallizes by evaporation in the form of sodium metaborate. enrich the crystal water ·

Groooaann describes in the journal Acte Hydrochim Hydrobiol 1981/9 »535-544 reversal of the treatment of boric acid-containing waste water. According to this method, the waste water is first pre-filtered» then oo pre-purify with a snow and ketax resin and cleanse in an inverted osmosis plant containing · ecetas · cellulose membrane · in this way · especially by ion exchange filtration · 40 to 45% boric acid is recovered and separates 94 to 96% radioactive products ·

K «H» 3ohennsen has a patent-protected method Verfahren zur Reiningung von Boreturo durch permoative Abtronnung ”in translation Method of purifying boric acid by peraeotive delay» NOR patent opium or 153 015 »according to which the boric acid-containing solutions are filtered by filtering agent and then oe but weakly ketone kaloxide removes loose alkali »Then the solution is subjected to inverse agitation in a device equipped with cellulose acetate pulverized · For a higher permeate yield, use a cascaded bonding process in the form of a constrate wipe · This yields a yield of 60 to 80% ·

The Soviet patent epio or 841 612 describes a method for denitretizing strongly waste reductions of waste liquids. The waste liquids are mixed with colium hydrogen sulphate and then the nitrate content is decomposed in a reaction space containing psreformeldshyd phosphoric acid at 110 ° C.

The aforementioned methods are not suitable for treating off-water in general in atomic power plants because their use is unconquered by various problems, for example, prior to inverted oozing, purification of the non-ionic wastes not only reduces but even increases » salts that do not give away from the radioactive substances later! »The regeneration efficiency of boric acid from ionoxinized water is relatively low, since about one part of the boric acid is bound by the enex · Basically, these processes are suitable for processing only alkaline nitrate-free boric acid solutions ·

CS 26BB21 02

According to the invention, it is possible to regenerate boric acid solutions by any means, either selectively or in combination with exacerbated technological solutions of waste water * of pumped waters or of their generating effluents at aton power plants without introducing additional inactive ions even in alkaline nitrate addition without significant increase. objeau deposited haot, while these acquired solutions of boreel cyeelines can be reused in the operation of aton power plants *

In the process according to the invention, the flocculants free of radioactive ions and the etethetic ions contaminated with borol cyanide solutions are introduced into the first oenosis apparatus for performing inverted oeaosis. the use of aeabrants in such oenotic devices * which retain alkali and heavy metal ions * which carry radioactivity carriers * at least 80% * while the retention value of boron kyaolin is at most 30 X · In this stage, a large proportion of radioactive and inactive salts are separated as contaminants boric acid and drain and into the so-called concentrate of the permeate permeate contains the largest part of boric acid cyanide to a second stage with a second device for performing inverted oeaosis · where ee further purifies * The second observation · which the invention is based on · is that in this oanorrhagic device it uses an arable * which retains alkaline ions of at least 00 X · boric acid, but not more than 40 X * * oWith the pereate of the second blunted boric acid, boric acid contains not less than 100 mg / l of nitrate ions | this aineal pollution with nitrates that can be removed on anion exchange resin *

The invention is further based on the discovery that the removal of residual eluting glycine nitrates from a boric acid cyeeline solution is carried out on a tacky and acoustically strong base hydrocarbonate enex resin in two of the two but separate columns separated by each other. during ion exchanger · when running columns oo boric acid and nitrate ions simultaneously bind to nnex *

In the course of ion exchanger, nitrate ions suppress freshly introduced filkallka nitrate and contaminated boric acid in solution form and enter the already resin-bound boric acid ions boric acid is greater than the paraaátu · solution of boric · processed first anaxováa column · still contains 2-5 eT / 1 duolčnanu _t which I for further processed too anobo · This residual obaah nitrate oo removed at a second step unbonded · ionexováa column * which also contains a bicarbonate cycle as a filler · regenerated boric acid loaded resin · The boric acid solution emerging from this stage is practically free of nitrates and can be re-introduced into the boron acid atyate · Renegerate of ion exchange elouoc as introduces attoa power plants into collection eyetáaó for inorganic wastes ·

To improve the efficiency of the borlether cyeeline recovery and reduce the volume of radioactivity debris *, the process has a third reverse oeaosis and recirculation · The first inverted oeaosis exiting * salt-free water concentrate · ее introduces a second inverted oeaozy · Third stage ee concentrates on ETHE as a radioactive waste · Third stage peraeate is introduced into the first stage pereaate · because it contains a significant amount of boric acid * The second stage pereeate concentrate is introduced into the first inverted oeaozy ·

The technological process illustrates the achane in Fig. 1

Example

In the wastewater-free radioactive flocculants 1 originating from unorganized screening processes · (boric cyeeline content 1.0 to 1 * 5 g / l, dueate ion content 0.5 to 1.0 g / l) the concentrate 2 of second stage, that this ee ee is processed in the first reverse oeaosis apparatus 3 at a pressure of 5 to 6 MPa.

CS 268821 82 must 4 is combined with permeate 5 from the third stage and is cleaned in a second reverse osmosis plant at a pressure of 3 to 4 MPa · Fermeate 7 from the second stage ee leaves on two »in a row of connected columns 8, 9 containing a strongly basic, macroporous anion exchange resin, * concentrate 2 from the second stage being fed back to the beginning of the system ·

The concentrate 10 of the first inverted oeaozye is diluted with domineralized water 11 to twice its volume in this form and ee processes the reverse inverted osmosis 12 at a pressure of 5-8. Osmosis is introduced into the system for the treatment of radioactive waste ·

80 to 90% by volume of the waste water treatment process is recoverable as a purified boric acid solution 14, the axis of radioactivity of the boric acid solution being reduced by 90-95%. The boric acid solution contains 75 to 80% of the stated amount of boric acid and not more than 1 g. / l nitrate * Remaining volume of radioactive waste solutions 13 represents 10 to 20% ·

Claims (4)

OBJECT OF THE INVENTION A method for recovering reusable boric acid solutions from radioactive contaminated technological waste of atomic power stations in nuclear power plants, radioactive waters, sedimentation waters and mixtures thereof, characterized in that radioactive waste and solutions are used under atomic storage and collection systems, after removal of floating substances, they treat in an apparatus for the first inverted oaaose, whose aeabrene retains alkali and heavy metal ion salts which are radioactive at least 80%, while boric acid of at most 30%, both of which are obtained from oamose solutions, from a concentrate containing a major amount of radioactivity-bearing substances and from a permeate containing a major amount of boric acid from a portion of the Slavic nitrate, the porsate is further processed in a second inverted osmosis plant, which is unresponsively retained by alkaline n at least 90%, but boric acid of at least 40%, the concentrate obtained in this stupefied concentrate returns to the first inverted oozosis, but the pormsate leads to macroporous strongly alkaline anion exchange resin containers arranged at least as a row of two columns to separate residual alkaline nitrate. purified boric acid solution containing less than 1/1000 X alkaline nitrates, oo introduces back to the boric acid treatment system at an atomic power plant, and a first stage concentrate, if any, boric acid content less than 1500 mg / l, oo introduces into radioactive processing waste, 2. The process of claim 1 wherein the first-stage concentrate containing more than 1500 g / l boric acid is diluted with demlnoralized water and introduced into a further inverted osmosis, the membrane standing upright as in the first osmosis stage and of this stage, the obtained psrmsate is processed from the permsate from the first stage, but the concentrate is introduced into the radioactive waste treatment · 3. A process according to claim 1, wherein the macroporous, strongly basic anoxic resins operate in a bicarbonate cycle and regenerate the first column of both axes in the row row if the boric acid solution at the outlet contains more than 5 g / l nitrate ions. 4. The method of claim 1, wherein the ee is operated with three degrees of reverse osmosis, with an anion exchange system having two or more columns and a respective generation unit.