EP0139955B1 - Procédé pour fixer les composants gazeux radioactifs des gaz d'échappement - Google Patents

Procédé pour fixer les composants gazeux radioactifs des gaz d'échappement Download PDF

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Publication number
EP0139955B1
EP0139955B1 EP84109730A EP84109730A EP0139955B1 EP 0139955 B1 EP0139955 B1 EP 0139955B1 EP 84109730 A EP84109730 A EP 84109730A EP 84109730 A EP84109730 A EP 84109730A EP 0139955 B1 EP0139955 B1 EP 0139955B1
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EP
European Patent Office
Prior art keywords
zeolite
range
temperature
water content
fixation
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
Application number
EP84109730A
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German (de)
English (en)
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EP0139955A2 (fr
EP0139955A3 (en
Inventor
Ralf-Dieter Dr. Penzhorn
Reinhard Dr. Kroebel
Peter Schuster
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Forschungszentrum Karlsruhe GmbH
Original Assignee
Kernforschungszentrum Karlsruhe GmbH
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Publication of EP0139955A3 publication Critical patent/EP0139955A3/de
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    • 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
    • G21F9/02—Treating gases

Definitions

  • the invention relates to a method for fixing radioactive, gaseous constituents of exhaust gases which are released during the reprocessing of irradiated or spent nuclear reactor fuel elements.
  • the nitrogen oxides are catalytically oxidized in a conventional device, absorbed in water and recycled as nitric acid. This is followed by particulate filters for removing the aerosols and an iodine absorber. An aerosol filter is then used again and C ⁇ Hy is then catalytically oxidized.
  • the CA 14 CO 3 obtained is then embedded in cement stone.
  • the typical composition of an exhaust gas from a reprocessing plant that reprocesses fuel elements from a gas-cooled high-temperature reactor is 95% C-14 contaminated C0 2 , 10 to 15 ppm Kr-85 contaminated krypton and approximately 60 ppm xenon.
  • C-14 is only a weak beta emitter, it poses a long-term risk due to its long half-life of 5730 years and its easy incorporability into the bio-cycle.
  • CO 2 is first removed the reaction with Ca (OH) 2 sludge is eliminated and the krypton is then removed using a fluorocarbon adsorption system.
  • the liquid loaded with Kr-85 is then placed in a scrubbing column where the krypton is separated from the liquid. After CO 2 removal, the gas flow is reduced to one twentieth of the original flow.
  • the gas then essentially consists only of nitrogen and oxygen.
  • C-14 can occur either as CO 2 or as a low molecular weight hydrocarbon.
  • CO 2 gas concentrations which contain traces of C-14 are to be expected in the range from 10 to 300 vpm.
  • the annual occurrence of C-14 different nuclear facilities depending on their performance is listed.
  • the product obtained from the CO 2 barium hydroxide octahydrate reaction must be incorporated in cement paste for final storage.
  • barium carbonate slurries can be introduced directly into the cement slurry after settling without first transferring the carbonate to the dry state.
  • a possible objection to the removal of C-14 in the form of BaCOg / cement hardening is the presence of soluble bicarbonate.
  • the cement slurry with its high pH provides protection for the BaC0 3 against attack by C0 2 . However, this protection will lapse if all of the Ca (OH) 2 in the cement slurry has been converted to CaC0 3 or if the cement paste has been dissolved or destroyed.
  • the iodine retained in the iodine absorber or the iodine compounds sorbed there on a silica-based carrier impregnated on a silver nitrate are solidified with the sorption material.
  • the invention has for its object to provide a less complex, easy to carry out fixation process for the radioactive, gaseous components of exhaust gases from the reprocessing of irradiated or spent nuclear reactor fuel elements, with which both the individual species of these components 14 CO 2 , 14 CH 4 , radioactive iodine isotopes, HTO vapor as well as any mixtures of these species in the molecular form in which they occur, ie without chemical conversion prior to fixation, can be irreversibly solidified in a matrix resistant to radioactive radiation, elevated temperature and leaching in water or saline solutions . In this case, irreversible means that there is practically no release of the gaseous constituents before the matrix is heated to temperatures at which it is decomposed or destroyed.
  • the zeolite is dried to a water content of 0.6 to 5% by weight, in the case of HTO fixation to a water content of 0.6 to 22% by weight .-%.
  • Mordenite as the fixation matrix can be used in the sodium-exchanged form and in the hydrogen-exchanged form.
  • the evacuation can be in the temperature range from 373 K to 473 K when using mordenite Na if the evacuation time is 16 hours. Good results with mordenite-Na were obtained if either evacuation was carried out at 473 K for 16 hours and the fixation of C0 2 took place at 793 K or if the vacuum was evacuated at 423 K for 16 hours and fixed at 923 K.
  • mordenite-H is used to fix CO 2 , the residual water content is advantageously set to 8% by weight or less.
  • the fixing temperatures can be between 823 and 923 K. A fixation of CO 2 in mordenite-H, which can be described as good, was obtained after 16 hours of evacuation at 373 K and a subsequent fixation at 923 K.
  • the residual water content should not be higher than 10% by weight.
  • a fixation temperature in the range of 733 K to 823 K is preferably used to fix CO 2 in clinoptilolite.
  • Table 5 shows that, although to a lesser extent, clinoptilolite, mordenite-Na and mordenite-H can be loaded with CO 2 and that this gas can be permanently fixed in the matrix mentioned.
  • FIG. 1 shows the dependence of the load on the fixing pressure used.
  • the fixation matrix it was evacuated at 473 K for 16 hours.
  • the loading curve was recorded at a fixation temperature of 793 K.
  • Zeolite 5A pellets were conditioned under vacuum at 440 K for the subsequent fixation of H 2 0. The duration of this pretreatment was 16 hours, the residual water content was 3.5% by weight.
  • a simulated, non-radioactive gas mixture which contained krypton and water vapor was then brought into contact with the zeolite 5A pellets and 20 standard cm 3 / g krypton with about 1% by weight H 2 0 at 790 K and a krypton pressure of 244 bar immobilized or fixed in the glazed zeolite.
  • HTO-labeled water was brought into contact with a zeolite 4A exchanged for a water content of 15 to 16% pretreated and isochorically heated in an autoclave at temperatures in the range from 420 K to 673 K.
  • the amount of water fixed after an aftertreatment at 420 K was, for example, 1% by weight at 420 K and 573 K and about 0.6% by weight at 673 K.
  • the tritium exchange rate was 0.017% per hour at room temperature, with HTO / H 2 O loaded zeolite samples are constantly circulated in water.
  • the experiment was carried out as described in Experiment 10, except that 3.5 kg of 5A zeolite were used as the fixation matrix.
  • the pretreatment also caused a residual water content of 2.3% by weight.
  • the specific surface area of the 5A zeolite was 480 m 2 / g.
  • the CO 2 was introduced into the autoclave under a sorption pressure of 1 bar.
  • Fixation pressure 198 bar, fixation temperature approx. 790 K.
  • a load of 32.9 standard cm 3 / g was found.
  • the surface area of the 5A amorphous zeolite after fixation was only 3 m 2 / g.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
  • Separation Of Gases By Adsorption (AREA)
  • Treating Waste Gases (AREA)

Claims (4)

1. Procédé pour la fixation des constituants gazeux radioactifs de gaz de combustion qui sont libérés pendant le retraitement d'éléments combustibles irradiés ou calcinés de réacteur nucléaire, caractérisé en ce que les constituants gazeux sont du 14CO2, 14CH4, les isotopes radioactifs de l'iode ou la vapeur d'eau tritiée ou le mélange de deux ou plusieurs de ces espèces et en tant que principe unitaire ou sous forme de leur mélange, dans la forme moléculaire dans laquelle ils se produisent avec une et même matière, est fixé avec un ou le même agent de fixation, une Zéolite du groupe de la Mordénite, Clinoptilolite, chabasite et Zéolite de type 4 (ayant une largeur de pore de 0,4 nm ou 0,5 nm conformément aux étapes du procédé suivantes consécutives:
a) évacuation de la Zéolite à une température dans la zone de 3200K à 720 °K jusqu'à une teneur en eau résiduelle de 0,6 à 22% en poids ou séchage de la Zéolite avec un courant d'air à la température ambiante ou avec un courant d'air chauffé dont la température de situe dans une zone de la température ordinaire jusqu'à 820°K.
b) adsorption des composants à fixer des gaz de combustion après refroidissement de la Zéolite prétraitée dans une zone de températures entre -30°C et +25°C et/ou par utilisation d'une pression dans la zone située entre la pression atmosphérique et 10 bars.
c) fixation des constituants de gaz de combustion adsorbés dans la Zéolite à une température dans la zone allant de 610°K à 920°K et à une pression dans la zone allant de 5 bars à 12000 bars.
2. Procédé selon la revendication 1, caractérisé en ce que la Zéolite est séchée dans le cas de la fixation du 14CO2 ou du 14CH4, jusqu'à une teneur en eau de 0,5 à 5% en poids.
3. Procédé selon la revendication 1, caractérisé en ce que la Zéolite, dans le cas de la fixation de l'iode, est séchée jusqu'à une teneur en eau de 0,6 à 5% en poids.
4. Procédé selon la revendication 1, caractérisé en ce que la Zéolite, dans le cas de la fixation d'eau Tritiée, est séchée jusqu'à une teneur en eau de 0,6 à 22% en poids.
EP84109730A 1983-08-24 1984-08-16 Procédé pour fixer les composants gazeux radioactifs des gaz d'échappement Expired EP0139955B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE3330460 1983-08-24
DE19833330460 DE3330460A1 (de) 1983-08-24 1983-08-24 Verfahren zur fixierung radioaktiver, gasfoermiger bestandteile von abgasen

Publications (3)

Publication Number Publication Date
EP0139955A2 EP0139955A2 (fr) 1985-05-08
EP0139955A3 EP0139955A3 (en) 1986-05-28
EP0139955B1 true EP0139955B1 (fr) 1988-12-28

Family

ID=6207276

Family Applications (1)

Application Number Title Priority Date Filing Date
EP84109730A Expired EP0139955B1 (fr) 1983-08-24 1984-08-16 Procédé pour fixer les composants gazeux radioactifs des gaz d'échappement

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EP (1) EP0139955B1 (fr)
DE (2) DE3330460A1 (fr)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE3525772C1 (de) * 1985-07-19 1986-09-04 Gkss - Forschungszentrum Geesthacht Gmbh, 2054 Geesthacht Verfahren zur endlagerreifen Konditionierung von Tritium
GB9523517D0 (en) * 1995-11-17 1996-01-17 British Nuclear Fuels Plc Separation of gases
WO2013081564A2 (fr) * 2011-11-04 2013-06-06 Kirveli Aziz Produits à base de zéolite modifiée, active, hydrophobe (aimant l'air), naturelle et procédés de production correspondants

Family Cites Families (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS51133700A (en) * 1975-05-15 1976-11-19 Nippon Atom Ind Group Co Ltd Process for storing the radioactive rare gas
US4088737A (en) * 1976-11-02 1978-05-09 The United States Of America As Represented By The United States Department Of Energy Dry method for recycling iodine-loaded silver zeolite
DE2948515C2 (de) * 1979-12-01 1983-12-22 Kernforschungszentrum Karlsruhe Gmbh, 7500 Karlsruhe Verfahren zur Fixierung von radioaktiven Edelgasen
DE3011602A1 (de) * 1980-03-26 1981-10-08 Kernforschungsanlage Jülich GmbH, 5170 Jülich Verfahren und vorrichtung zur endlagerung von tritium, insbesondere tritiumabfaellen aus kernkraftwerken, mit der moeglichkeit der tritiumrueckgewinnung

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Publication number Publication date
DE3330460A1 (de) 1985-03-07
EP0139955A2 (fr) 1985-05-08
EP0139955A3 (en) 1986-05-28
DE3475846D1 (en) 1989-02-02

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