Compositions – Radioactive compositions
Patent
1985-03-21
1987-06-09
Lechert, Jr., Stephen J.
Compositions
Radioactive compositions
110237, 159 473, 252626, 252631, G21F 916
Patent
active
046718982
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL AREA
The present invention relates to a process for the treatment of a spent, radioactive, organic ion exchange resin to reduce the volume thereof and to obtain a stable final product. In the context ion exchange resin primarily means a cationic exchange resin but also an anionic exchange resin and an exchange resin of the mixed bed type, containing cation exchanger as well as anion exchanger, can be advantageously treated in accordance with the invention. The invention primarily relates to the treatment of such ion exchange resins which have been utilized to purify cooling water in a nuclear reactor, and the water in a pool for the storage of spent nuclear fuel.
TECHNICAL BACKGROUND
It is previously known to solidify a spent ion exchange resin in cement or bitumen. However, by such a measure the volume is heavily increased. Furthermore, in the case of solidification in cement, the stability against leaching is not very good. In the case of solidification in bitumen the fire hazards thereof is a problem.
Moreover, it is previously known, for instance from Swedish patent specification No. 8101801-2, that the volume of a spent ion exchange resin can be reduced by an incineration thereof. According to said Swedish patent specification the incineration residue is then heated to sintering or melting, a stable product being obtained thereby. The measure of cementing the incineration residue has been considered improper due to the bad stability against leaching which has been observed when solidifying a non-incinerated ion exchange resin in cement.
DISCLOSURE OF THE INVENTION
It has now been found that in an unexpectedly simple way it is possible to reduce the volume of the spent ion exchange resin as well as to prepare a cement matrix wherein the radioactive nucleides are bound in a stable way. The process according to the invention is characterized by mixing the ion exchange resin partly with a salt, to liberate radioactive substances from the ion exchange resin, partly with an inorganic sorbent for the radioactive substances thus liberated, then drying and incinerating the mixture, and solidifying in cement the residue from the incineration.
The salt may be added to the aqueous ion exchanger in a solid form or as an aqueous solution thereof. The salt is preferably added in such a quantity that the ion exchanger will be saturated. The cation of the salt should effectively elute active ions, such as Cs.sup.+ -ions, wich are sorbed on the ion exchanger. In order to obtain such an elution it is possible to utilize several common water-soluble salts, such as calcium nitrate or aluminium nitrate.
However, according to the invention it is preferable to use water-soluble salts, the anions of which tend to liberate active nucleides, such as cobolt, zinc, through the formation of complexes, for instance salts of phosphoric acid, citric acid, tartaric acid, oxalic acid, formic acid, propionic acid. It has turned out that such complex-forming anions do not disturb the subsequent process steps, i.e. the incineration and cementation operations, and that said organic acids are eliminated in the incineration step. As cations of the salt calcium and aluminium are preferred. These salts are conducive to a favourable course of incineration. The explanation thereto seems to be that after their sorption on the ion exchanger the salts make said ion exchanger rather heavy, which facilitates the incineration. Furthermore, these salt reduce the tendency to an agglomeration of the ion exchange resin grains, which results in a larger contact surface towards the incineration air and a more rapid incineration. Salts of calcium and aluminium make the incineration residue more compatible with the cement matrix, and accordingly the solidification in cement will be facilitated.
The inorganic sorbent should be added in such an amount that it completely sorbs the liberated radioactive nucleides. Preferably the sorbent has a particle size of 10-100 .mu.m. During the incineration operation the sorbent will retain radioactive nucl
REFERENCES:
patent: 3479295 (1969-11-01), Thompson
patent: 3988258 (1976-10-01), Curtiss et al.
patent: 4008171 (1977-02-01), Tiepel et al.
patent: 4053432 (1977-10-01), Tiepel et al.
patent: 4122048 (1978-10-01), Buchwalder et al.
patent: 4204974 (1980-05-01), Puthawala et al.
patent: 4268409 (1981-05-01), Ga et al.
patent: 4401591 (1983-08-01), Korostenski
patent: 4460500 (1984-07-01), Hultgren
patent: 4499833 (1985-02-01), Grantham
patent: 4530723 (1985-07-01), Smeltzer et al.
Lechert Jr. Stephen J.
Locker Howard J.
Studsvik Energiteknik AB
LandOfFree
Process for treatment of a spent, radioactive, organic ion excha does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for treatment of a spent, radioactive, organic ion excha, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for treatment of a spent, radioactive, organic ion excha will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1827644