JPH01114799A - Method for concentrating waste nitric acid solution - Google Patents
Method for concentrating waste nitric acid solutionInfo
- Publication number
- JPH01114799A JPH01114799A JP27377887A JP27377887A JPH01114799A JP H01114799 A JPH01114799 A JP H01114799A JP 27377887 A JP27377887 A JP 27377887A JP 27377887 A JP27377887 A JP 27377887A JP H01114799 A JPH01114799 A JP H01114799A
- Authority
- JP
- Japan
- Prior art keywords
- nitric acid
- concentration
- vessel
- water
- evaporation
- 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.)
- Granted
Links
- GRYLNZFGIOXLOG-UHFFFAOYSA-N Nitric acid Chemical compound O[N+]([O-])=O GRYLNZFGIOXLOG-UHFFFAOYSA-N 0.000 title claims abstract description 107
- 229910017604 nitric acid Inorganic materials 0.000 title claims abstract description 107
- 239000002699 waste material Substances 0.000 title claims abstract description 47
- 238000000034 method Methods 0.000 title claims abstract description 28
- 239000007788 liquid Substances 0.000 claims abstract description 55
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 40
- 229910001868 water Inorganic materials 0.000 claims abstract description 40
- 238000001704 evaporation Methods 0.000 claims abstract description 30
- 230000008020 evaporation Effects 0.000 claims abstract description 24
- 238000010438 heat treatment Methods 0.000 claims abstract description 8
- 239000007864 aqueous solution Substances 0.000 claims description 17
- 239000003513 alkali Substances 0.000 claims description 13
- 239000000243 solution Substances 0.000 claims description 12
- QGZKDVFQNNGYKY-UHFFFAOYSA-N ammonia Natural products N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 claims description 7
- ZBCBWPMODOFKDW-UHFFFAOYSA-N diethanolamine Chemical compound OCCNCCO ZBCBWPMODOFKDW-UHFFFAOYSA-N 0.000 claims description 2
- VHUUQVKOLVNVRT-UHFFFAOYSA-N Ammonium hydroxide Chemical compound [NH4+].[OH-] VHUUQVKOLVNVRT-UHFFFAOYSA-N 0.000 claims 1
- 239000000203 mixture Substances 0.000 claims 1
- 230000007423 decrease Effects 0.000 abstract description 11
- 229910021645 metal ion Inorganic materials 0.000 abstract description 9
- 238000007738 vacuum evaporation Methods 0.000 abstract description 6
- 230000002285 radioactive effect Effects 0.000 abstract description 5
- 150000001412 amines Chemical class 0.000 abstract description 3
- 230000003247 decreasing effect Effects 0.000 abstract description 3
- 239000003595 mist Substances 0.000 abstract description 3
- 239000002994 raw material Substances 0.000 abstract description 2
- 230000002250 progressing effect Effects 0.000 abstract 1
- 238000007670 refining Methods 0.000 abstract 1
- 230000000694 effects Effects 0.000 description 13
- 238000005260 corrosion Methods 0.000 description 8
- 230000007797 corrosion Effects 0.000 description 8
- 230000008569 process Effects 0.000 description 8
- 230000000052 comparative effect Effects 0.000 description 7
- 230000033228 biological regulation Effects 0.000 description 6
- MWUXSHHQAYIFBG-UHFFFAOYSA-N nitrogen oxide Inorganic materials O=[N] MWUXSHHQAYIFBG-UHFFFAOYSA-N 0.000 description 6
- 238000003860 storage Methods 0.000 description 6
- 239000012670 alkaline solution Substances 0.000 description 5
- 239000012141 concentrate Substances 0.000 description 5
- QUSNBJAOOMFDIB-UHFFFAOYSA-N Ethylamine Chemical compound CCN QUSNBJAOOMFDIB-UHFFFAOYSA-N 0.000 description 4
- HQABUPZFAYXKJW-UHFFFAOYSA-N butan-1-amine Chemical compound CCCCN HQABUPZFAYXKJW-UHFFFAOYSA-N 0.000 description 4
- 238000010586 diagram Methods 0.000 description 4
- 238000011017 operating method Methods 0.000 description 4
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 description 3
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 description 3
- 229910021529 ammonia Inorganic materials 0.000 description 3
- -1 cesium and strontium Chemical class 0.000 description 3
- 238000005868 electrolysis reaction Methods 0.000 description 3
- 239000007789 gas Substances 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 238000006386 neutralization reaction Methods 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 239000000941 radioactive substance Substances 0.000 description 3
- 238000012958 reprocessing Methods 0.000 description 3
- 239000008400 supply water Substances 0.000 description 3
- 238000004017 vitrification Methods 0.000 description 3
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 description 2
- BAVYZALUXZFZLV-UHFFFAOYSA-N Methylamine Chemical compound NC BAVYZALUXZFZLV-UHFFFAOYSA-N 0.000 description 2
- 229910002651 NO3 Inorganic materials 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- 229910052783 alkali metal Inorganic materials 0.000 description 2
- 150000001340 alkali metals Chemical class 0.000 description 2
- 229910052788 barium Inorganic materials 0.000 description 2
- DSAJWYNOEDNPEQ-UHFFFAOYSA-N barium atom Chemical compound [Ba] DSAJWYNOEDNPEQ-UHFFFAOYSA-N 0.000 description 2
- 229910052792 caesium Inorganic materials 0.000 description 2
- TVFDJXOCXUVLDH-UHFFFAOYSA-N caesium atom Chemical compound [Cs] TVFDJXOCXUVLDH-UHFFFAOYSA-N 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 2
- PAFZNILMFXTMIY-UHFFFAOYSA-N cyclohexylamine Chemical compound NC1CCCCC1 PAFZNILMFXTMIY-UHFFFAOYSA-N 0.000 description 2
- 238000011038 discontinuous diafiltration by volume reduction Methods 0.000 description 2
- 239000012527 feed solution Substances 0.000 description 2
- 230000004992 fission Effects 0.000 description 2
- 239000002244 precipitate Substances 0.000 description 2
- 239000012857 radioactive material Substances 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 238000005185 salting out Methods 0.000 description 2
- 150000003839 salts Chemical class 0.000 description 2
- 239000002915 spent fuel radioactive waste Substances 0.000 description 2
- 229910052723 transition metal Inorganic materials 0.000 description 2
- 150000003624 transition metals Chemical class 0.000 description 2
- BMVXCPBXGZKUPN-UHFFFAOYSA-N 1-hexanamine Chemical compound CCCCCCN BMVXCPBXGZKUPN-UHFFFAOYSA-N 0.000 description 1
- NHNBFGGVMKEFGY-UHFFFAOYSA-N Nitrate Chemical compound [O-][N+]([O-])=O NHNBFGGVMKEFGY-UHFFFAOYSA-N 0.000 description 1
- 229910052778 Plutonium Inorganic materials 0.000 description 1
- KJTLSVCANCCWHF-UHFFFAOYSA-N Ruthenium Chemical compound [Ru] KJTLSVCANCCWHF-UHFFFAOYSA-N 0.000 description 1
- 229910052770 Uranium Inorganic materials 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 150000008044 alkali metal hydroxides Chemical class 0.000 description 1
- 229910052784 alkaline earth metal Inorganic materials 0.000 description 1
- 229910001860 alkaline earth metal hydroxide Inorganic materials 0.000 description 1
- 150000001342 alkaline earth metals Chemical class 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- WYKYKTKDBLFHCY-UHFFFAOYSA-N chloridazon Chemical compound O=C1C(Cl)=C(N)C=NN1C1=CC=CC=C1 WYKYKTKDBLFHCY-UHFFFAOYSA-N 0.000 description 1
- 238000009833 condensation Methods 0.000 description 1
- 230000005494 condensation Effects 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 230000001419 dependent effect Effects 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 239000000446 fuel Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 239000002927 high level radioactive waste Substances 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 238000007689 inspection Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- VUZPPFZMUPKLLV-UHFFFAOYSA-N methane;hydrate Chemical compound C.O VUZPPFZMUPKLLV-UHFFFAOYSA-N 0.000 description 1
- 230000003472 neutralizing effect Effects 0.000 description 1
- 150000002823 nitrates Chemical class 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- OYEHPCDNVJXUIW-UHFFFAOYSA-N plutonium atom Chemical compound [Pu] OYEHPCDNVJXUIW-UHFFFAOYSA-N 0.000 description 1
- 150000003141 primary amines Chemical class 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 229910052707 ruthenium Inorganic materials 0.000 description 1
- 150000003335 secondary amines Chemical class 0.000 description 1
- 238000007711 solidification Methods 0.000 description 1
- 230000008023 solidification Effects 0.000 description 1
- 229910052712 strontium Inorganic materials 0.000 description 1
- CIOAGBVUUVVLOB-UHFFFAOYSA-N strontium atom Chemical compound [Sr] CIOAGBVUUVVLOB-UHFFFAOYSA-N 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 150000003512 tertiary amines Chemical class 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- JFALSRSLKYAFGM-UHFFFAOYSA-N uranium(0) Chemical compound [U] JFALSRSLKYAFGM-UHFFFAOYSA-N 0.000 description 1
- 238000001771 vacuum deposition Methods 0.000 description 1
Landscapes
- Heat Treatment Of Water, Waste Water Or Sewage (AREA)
Abstract
Description
【発明の詳細な説明】
〔産業上の利用分野〕
本発明は、放射性物質を多量に含んだ硝酸廃液の濃縮方
法に係り、特に硝酸濃度の低減に好適な運転方法に関す
る。DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for concentrating nitric acid waste liquid containing a large amount of radioactive substances, and particularly to an operating method suitable for reducing the nitric acid concentration.
放射性物質を多量を含んだ硝酸廃液（高レベル廃液）は
、貯蔵用タンクの小型化、取り扱い操作の簡便さ、安全
性の観点から、できる限り減容したのち、−時的に溶液
のまま貯蔵用タンクで貯蔵される。使用済み核燃料再処
理の一方法であるビューレックス法においては、使用済
み核燃料を溶解した硝酸水溶液から再度燃料として使用
できるウランとプルトニウムを抽出したのちの廃液が放
射性物質を多量に含んだ硝酸廃液となる。この廃液中で
は、放射性物質は核分裂生成物と呼ばれるセシウム、ス
トロンチウム等のアルカリ金属類。Nitric acid waste liquid (high-level waste liquid) containing a large amount of radioactive materials is reduced in volume as much as possible from the viewpoint of downsizing the storage tank, ease of handling, and safety, and then temporarily stored as a solution. stored in storage tanks. In the Burex method, which is a method for reprocessing spent nuclear fuel, uranium and plutonium, which can be used as fuel again, are extracted from a nitric acid aqueous solution in which spent nuclear fuel is dissolved. Become. The radioactive substances in this waste liquid are alkali metals such as cesium and strontium, which are called nuclear fission products.
バリウム等のアルカリ土類、またパラジウム等の遷移金
属類、さらには超ウラン元素などの約３０数種の金属イ
オンである。しかるに、廃液中の体積の大部分を占める
水および硝酸は、放射性をもたない。そのため、該廃液
の減容工程は、水および硝酸を除去することにより、放
射能をもつ核分裂生成物を濃縮するのが最も効率的であ
る。この水および硝酸除去の従来法は、（１）電解によ
り水および硝酸を分解ガス化する方法（特開昭５７−１
２８８９２号公報）と、（２）硝酸を減圧下で蒸発させ
る方法の２つが知られている。These are about 30 metal ions, such as alkaline earth metals such as barium, transition metals such as palladium, and transuranium elements. However, water and nitric acid, which make up most of the volume in the waste liquid, are not radioactive. Therefore, in the volume reduction process of the waste liquid, it is most efficient to concentrate the radioactive fission products by removing water and nitric acid. Conventional methods for removing water and nitric acid include (1) a method of decomposing and gasifying water and nitric acid by electrolysis (Japanese Patent Laid-Open No. 57-1
28892) and (2) a method of evaporating nitric acid under reduced pressure.
前記（１）の方法は、廃液中の水、硝酸を電解により水
素、酸素、窒素、窒素酸化物に分解ガス化するものであ
り、無害なガスとして回収する有効な方式である。しか
し、電解工程は、大量の廃液を処理する場合装置が大型
化し、また電力コストが高いという問題がある。The method (1) above decomposes and gasifies water and nitric acid in waste liquid into hydrogen, oxygen, nitrogen, and nitrogen oxides by electrolysis, and is an effective method for recovering harmless gases. However, the electrolysis process has problems in that the equipment becomes large when processing a large amount of waste liquid, and the electricity cost is high.
前記（２）の方法は、単純な減圧蒸発であり、機器およ
び操作が簡略化される利点があるが、蒸発缶中の硝酸濃
度が初期の３規定から濃縮終了時には７規定程度まで上
昇する。硝酸濃度が７規定では、腐食に対する耐久性が
問題となるため、本方式では、スチームストリッピング
と呼ばれる方法で、濃縮後の硝酸廃液を７規定から３規
定程度まで硝酸濃度を低減させる。しかし、このスチー
ムストリッピングに多大の時間を要するという間開があ
る。The method (2) is simple evaporation under reduced pressure and has the advantage of simplifying the equipment and operation, but the nitric acid concentration in the evaporator rises from 3N at the initial stage to about 7N at the end of concentration. When the nitric acid concentration is 7N, durability against corrosion becomes a problem, so in this method, the nitric acid concentration of the concentrated nitric acid waste liquid is reduced from 7N to about 3N by a method called steam stripping. However, there is a drawback in that this steam stripping takes a lot of time.
これら上記従来技術は、機器が大型かつ複雑化し、コス
ト上昇となるか、もしくは腐食低減を図るために濃縮廃
液中の硝酸濃度を多大の時間をかけて低下させる必要が
あった。In these conventional techniques, the equipment becomes large and complicated, leading to an increase in cost, or it is necessary to reduce the nitric acid concentration in the concentrated waste liquid over a long period of time in order to reduce corrosion.
本発明の目的は、簡略化した機器および運転でも十分な
る廃液濃縮を可能せしむることにある。An object of the present invention is to enable sufficient concentration of waste liquid with simplified equipment and operation.
すなわち、装置的に簡略な減圧蒸発において濃縮後の高
濃度となった硝酸を迅速にその濃度を低減させる簡便な
運転方法を提供することにある。That is, the object of the present invention is to provide a simple operating method for quickly reducing the concentration of nitric acid that has become highly concentrated after being concentrated in vacuum evaporation, which is simple in terms of equipment.
上記目的は、減圧蒸発終了後、すなわち濃縮後の高濃度
硝酸に熱分解可能なアルカリ性水溶液を供給しながらさ
らに減圧蒸発することで達成される。The above object is achieved by further evaporating under reduced pressure after the completion of evaporation under reduced pressure, that is, while supplying an alkaline aqueous solution that can be thermally decomposed to the highly concentrated nitric acid after concentration.
従来からの減圧蒸発法では、放射性物質を含む硝酸廃液
は濃縮終了後に硝酸濃度が７規定程度まで上昇し、これ
をそのまま貯蔵するには腐食への耐久性が問題となるた
め、水を供給しながらさらに減圧蒸発を実施するスチー
ムストリッピングと呼ばれる方法で硝酸濃度を低減させ
る。しかし、この方法では、硝酸濃度の低減に多大な時
間を要する。In the conventional vacuum evaporation method, the nitric acid concentration of waste nitric acid containing radioactive materials rises to about 7N after concentration, and if it is stored as is, durability against corrosion becomes a problem, so water is not supplied. However, the nitric acid concentration is further reduced by a method called steam stripping, which involves evaporation under reduced pressure. However, this method requires a lot of time to reduce the nitric acid concentration.
本発明では、このスチームストリッピング時に供給する
水に代えて熱分解可能なアルカリ性水溶液を供給するこ
とで、迅速に硝酸濃度を低減するものである。In the present invention, the nitric acid concentration is rapidly reduced by supplying a thermally decomposable alkaline aqueous solution instead of the water supplied during steam stripping.
以下１本発明を見い出すに至った実験的事実とアルカリ
性水溶液を供給しながらの減圧蒸発の作用について説明
する。The experimental facts that led to the discovery of the present invention and the effect of vacuum evaporation while supplying an alkaline aqueous solution will be explained below.
放射性核種を含む硝酸廃液の減圧濃縮中の硝酸濃度は、
放射性核種の存在量によって影響を受ける。放射性核種
は、その大部分がアルカリ金属。The nitric acid concentration during vacuum concentration of nitric acid waste liquid containing radionuclides is:
Affected by the abundance of radionuclides. Radionuclides are mostly alkali metals.
遷移金属等の金属イオンであり、これが多量に存在する
場合は、塩析効果により硝酸−水の気液平衡関係が影響
を受け、硝酸の蒸発が促進される。These are metal ions such as transition metals, and if they exist in large amounts, the vapor-liquid equilibrium relationship between nitric acid and water is affected by the salting-out effect, and the evaporation of nitric acid is promoted.
第２図に、再処理工程からの硝酸廃液を模擬した溶液で
、減圧蒸発を実施した例を示す。これは、蒸発缶液量２
０ｆｌに模擬廃液を２１２／ｈで供給し、圧力５０Ｔｏ
ｒｒで連続運転した結果であるが、硝酸−水のみでは蒸
発缶中の硝酸濃度は約１０規定で一定となるが、模擬廃
液では一旦１ｏ規定まで上昇したのち、上述の金属イオ
ンの塩析効果により硝酸濃度が徐々に減少していき、濃
縮度２０では約７規定となる。濃縮度をさらに上げれば
、硝酸濃度はさらに低下することが予想されるが、その
場合、硝酸溶液中の金属イオン、すなわち放射性核種が
沈澱を始めるため、硝酸濃度はあまり低下しない。また
、沈澱物を含む濃縮廃液は、その移送、壁面への付着、
すきま腐食等の問題があり、濃縮度２０が限界である。FIG. 2 shows an example in which vacuum evaporation was performed using a solution simulating the nitric acid waste liquid from the reprocessing process. This is the evaporator liquid volume 2
The simulated waste liquid was supplied to 0 fl at a rate of 212/h, and the pressure was 50 To.
The results of continuous operation at rr show that when using only nitric acid and water, the nitric acid concentration in the evaporator remains constant at about 10N, but in the simulated waste liquid, it once rises to 1ON, and then the above-mentioned salting-out effect of metal ions occurs. The nitric acid concentration gradually decreases, and at a concentration of 20, it becomes about 7N. If the concentration is further increased, it is expected that the nitric acid concentration will further decrease, but in that case, the metal ions, that is, the radionuclides in the nitric acid solution will begin to precipitate, so the nitric acid concentration will not decrease much. In addition, concentrated waste liquid containing precipitates should be transported, adhered to walls,
There are problems such as crevice corrosion, and a concentration level of 20 is the limit.
したがって、減圧蒸発法による濃縮廃液の硝酸濃度も７
規定以下にするのが極めて難しい。Therefore, the nitric acid concentration of the concentrated waste liquid obtained by the reduced pressure evaporation method is also 7.
It is extremely difficult to keep it below the standard.
濃縮廃液は、蒸発缶から貯蔵タンクに移送され、最終的
にはガラス固化４本となるが、特に貯蔵タンクでの貯蔵
工程では、硝酸濃度の低減が望まれている。なんとなれ
ば、貯蔵タンクは、固化工程にいくまでの期間保持する
ためのものであるが、その期間は場合によっては１０年
を超えることもあり得るため、機器構造材の腐食が重要
な要素となる。腐食の速度は、硝酸濃度に極めて依存し
ており、腐食を低減させるためには、硝酸濃度を低くす
る必要がある。The concentrated waste liquid is transferred from the evaporator to the storage tank, and is finally vitrified into four bottles. Especially in the storage process in the storage tank, it is desired to reduce the nitric acid concentration. Storage tanks are used to hold equipment for a period of time until it goes through the solidification process, which can exceed 10 years in some cases, so corrosion of equipment structural materials is an important factor. Become. The rate of corrosion is highly dependent on the nitric acid concentration, and to reduce corrosion it is necessary to lower the nitric acid concentration.
本発明においては、濃縮後の濃度７規定の硝酸廃液を、
さらに熱分解性アルカリ性水溶液を添加しながら減圧蒸
発実施することで硝酸濃度を低減する。第２図に示した
硝酸濃度の変化は、供給液を３．２規定の模擬硝酸溶液
を用いた場合であり、濃縮終了後にその供給液を水に変
えることで、硝酸濃度を低減できることが予想される。In the present invention, nitric acid waste liquid with a concentration of 7N after concentration is
Furthermore, the nitric acid concentration is reduced by performing evaporation under reduced pressure while adding a pyrolyzable alkaline aqueous solution. The change in nitric acid concentration shown in Figure 2 is when a 3.2N simulated nitric acid solution is used as the feed solution, and it is expected that the nitric acid concentration can be reduced by changing the feed solution to water after the completion of concentration. be done.
すなわち、蒸発工程を考えれば、蒸発缶からは水と硝酸
が蒸発しており、この蒸発の成分比は、缶液中の硝酸濃
度で決定されている。この缶液中に水を供給し、その供
給量と同量の蒸発が生じており、その蒸発成分中には、
缶液の硝酸濃度で決定される硝酸分が必ず含まれること
になり、結果として缶液中の硝酸濃度が徐々に減少して
いくことになる。本運転方法によれば、廃液中の放射性
核種の濃縮度を２０に保ったままで、硝酸濃度の低減が
可能となる。That is, considering the evaporation process, water and nitric acid are evaporated from the evaporator, and the component ratio of this evaporation is determined by the nitric acid concentration in the can liquid. Water is supplied into this tank liquid, and evaporation occurs in the same amount as the amount of water supplied, and the evaporated components include:
The nitric acid content determined by the nitric acid concentration in the can liquid will always be included, and as a result, the nitric acid concentration in the can liquid will gradually decrease. According to this operating method, it is possible to reduce the nitric acid concentration while maintaining the concentration of radionuclides in the waste liquid at 20.
第３図に、水供給による結果の一例を示す。これは、２
０ρの７規定硝酸中に２Ｑ／ｈの水を供給し、蒸発量も
２Ｑ／ｈとして計算評価したものである。これによると
、７規定から５規定までは比較的速く低下するが、５規
定から３規定まではさらに８日以上を要することがわか
る。運転方法を、供給量を４ ｆｉ／ｈ、蒸発量を４
Ｑ／ｈとすれば、３規定までの日数は減少するが、その
際蒸発量が増えるため、加熱要量を倍にする必要がでて
くる。FIG. 3 shows an example of the results obtained by water supply. This is 2
Calculations and evaluations were made by supplying 2Q/h of water into 7N nitric acid at 0ρ and assuming that the evaporation amount was also 2Q/h. According to this, it can be seen that the decrease is relatively fast from the 7th standard to the 5th standard, but it takes 8 days or more to go from the 5th standard to the 3rd standard. The operating method is: supply rate is 4 fi/h, evaporation rate is 4
If it is Q/h, the number of days until the 3rd standard decreases, but the amount of evaporation increases at that time, so it becomes necessary to double the amount of heating required.
再処理プロセスでは、装置の信頼性確保のために定常運
転をしており、運転条件を変更することは信頼性の点で
問題がある。すなわち、濃縮運転時に滞留時間（缶液量
／供給速度）を１０ｂとした場合、その後の水供給時も
滞留時間１０ｈが望まれる。第２図および第３図によれ
ば、濃縮運転時に要する日数が８日、その後の水供給に
よる硝酸濃度低減（３規定まで）に要する日数は１０日
となる。In the reprocessing process, steady operation is performed to ensure the reliability of the equipment, and changing operating conditions poses a problem in terms of reliability. That is, when the residence time (canned liquid amount/feed rate) is set to 10 b during concentration operation, the residence time is desired to be 10 h during subsequent water supply. According to FIGS. 2 and 3, the number of days required for the concentration operation is 8 days, and the number of days required for subsequent reduction of the nitric acid concentration (up to 3 standards) by water supply is 10 days.
硝酸濃度の低減速度をさらに上げるためには、供給水に
アルカリ成分を添加することで、蒸発の効果に中和効果
を加えるのが有効である。アルカリの中和剤添加は、酸
濃度低減には劇的な効果があるが、廃液中の塩濃度が増
大し、放射性物質の沈澱生成、ガラス固化時の廃液物量
増大の欠点があり、これまで実施されていなかった。本
発明では、上述の水供給による蒸発の効果と併用するこ
とで添加量を極力低減し、さらにガラス固化時に熱分解
されてガス化するアルカリ成分を用いることで解決した
。すなわち、第３図によると７規定から５規定までは短
時間に硝酸濃度が低減し、この間はアルカリ添加でも水
添加でもいずれでも変わりなく、これ以後にアルカリ水
溶液を供給する。In order to further increase the rate of reduction in nitric acid concentration, it is effective to add a neutralizing effect to the evaporation effect by adding an alkaline component to the supplied water. Addition of an alkaline neutralizer has a dramatic effect on reducing acid concentration, but has the drawbacks of increasing the salt concentration in the waste liquid, forming precipitates of radioactive substances, and increasing the amount of waste liquid during vitrification. It had not been implemented. In the present invention, the problem was solved by reducing the amount added as much as possible by combining the above-mentioned evaporation effect by supplying water, and further by using an alkali component that is thermally decomposed and gasified during vitrification. That is, according to FIG. 3, the nitric acid concentration decreases in a short time from 7N to 5N, and during this period, there is no difference whether alkali or water is added, and after this point, an aqueous alkali solution is supplied.
この際も、蒸発の効果も併用するため、低濃度のアルカ
リ溶液を供給することで、アルカリ添加量を最小限に抑
えることが可能となる。例えば、アルカリ添加時の硝酸
濃度が５規定であり、その後３規定まで低減するとすれ
ば、蒸発効果と併用することで、アルカリによる中和を
１．５規定分、蒸発効果を０．５規定分として実施すれ
ば、７規定から３規定まで約３日で可能となる。また、
全てを中和で実施すれば、４規定分のアルカリが必要と
なるが、本法では１．５規定分のアルカリで可能となる
６
一方、本法においても、廃液中に１．５規定分のアルカ
リ成分を添加しており、これは溶液中では硝酸イオンと
結合した塩としてふるまい、ガラス同化時の容量増大の
原因になり得る。事実、アルカリ成分として最も一般的
な水酸化ナトリウム、水酸化カリウム等のアルカリ金属
の水酸化物、アルカリ土類金属の水酸化物を用いた場合
は、その金属が同化体中に残存して容積が増大する。固
化体の作製および処分に十分なる余裕がある場合には−
向かまわないが、減容が必要な場合には高温時、すなわ
ち約５００℃以上で熱分解するアルカリ成分を用いるこ
とで解決する必要がある。５００°Ｃ以上で熱分解する
アルカリ成分としては、第１級、第２級、第３級のアミ
ン類およびアンモニア等が挙げられる。アンモニアは硝
酸との爆発的な反応の危険があるため、アミン類がより
好適である。例えば、エチルアミン、エチレンジアミン
。At this time, since the effect of evaporation is also used, by supplying a low concentration alkaline solution, it is possible to minimize the amount of alkali added. For example, if the nitric acid concentration at the time of alkali addition is 5N, and is then reduced to 3N, by using it in conjunction with the evaporation effect, the neutralization by the alkali will be 1.5N, and the evaporation effect will be 0.5N. If implemented as follows, it will be possible to go from 7 regulations to 3 regulations in about 3 days. Also,
If all neutralization was carried out, 4N worth of alkali would be required, but with this method it is possible to use 1.5N worth of alkali. This alkaline component behaves as a salt combined with nitrate ions in solution, which can cause an increase in capacity during glass assimilation. In fact, when alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, which are the most common alkaline components, and alkaline earth metal hydroxides are used, the metals remain in the assimilate and the volume increases. increases. If there is sufficient time to prepare and dispose of the solidified material -
However, if volume reduction is necessary, it is necessary to solve the problem by using an alkali component that thermally decomposes at high temperatures, that is, at about 500° C. or higher. Examples of the alkaline component that thermally decomposes at 500°C or higher include primary, secondary, and tertiary amines, ammonia, and the like. Since ammonia risks explosive reaction with nitric acid, amines are more preferred. For example, ethylamine, ethylenediamine.
ブチルアミン、シクロヘキシルアミン等であり、これら
はアンモニアと同等のアルカリ強度を有し、硝酸を等モ
ルで中和する。また、水中には任意の割合で溶解し、５
００℃以上では熱分解により二酸化炭素、水、窒素酸化
物に化学変化するため、ガラス固化体には残らず、容積
の増量とならない。Butylamine, cyclohexylamine, etc., have alkaline strength equivalent to ammonia and neutralize nitric acid in equimolar amounts. In addition, it dissolves in water at any ratio, and
At temperatures above 00° C., it chemically changes into carbon dioxide, water, and nitrogen oxides due to thermal decomposition, so it does not remain in the vitrified material and does not increase in volume.
以上述べたごとく、放射性核種を濃縮後の硝酸廃液の硝
酸濃度を、本発明による水供給による蒸発効果と、熱分
解可能なアルカリ添加により、迅速にしかもに６乗物量
を増容せずに低減することが可能である。次に、実施例
に基づいて本発明の有効性を述べる。As described above, the nitric acid concentration in the nitric acid waste solution after concentrating radionuclides can be reduced quickly and without increasing the volume of the 6th product by the evaporation effect of the water supply according to the present invention and the addition of a thermally decomposable alkali. It is possible to do so. Next, the effectiveness of the present invention will be described based on Examples.
本発明の実施例を第１図により説明する。同図は、放射
性核種を多量に含む高レベル硝酸廃液の減圧濃縮システ
ムを示しているが、以下の実施例では、模擬廃液を用い
た結果を中心に述べる。硝酸濃縮缶１中に、予め２０Ｑ
の硝酸廃液を模擬した模擬廃液を入れておく。模擬廃液
は、放射性核種と同一元素であるが、放射能をもたない
安定元素を硝酸に溶解したものであり、その元素の種類
は、セシウム、バリウム、ルテニウム等で３０種類とし
、その濃度は処理プロセスでの平均的な値とし、元素全
体で０．０５ｍｏＱ／Ｑ、硝酸濃度を３．２規定とした
。濃縮缶中の濃縮缶液２は、ヒータ用電源５と連結した
ヒータ４により加熱される。また、濃縮システムは、真
空排気装置１０により常時５０Ｔｏｒｒに減圧した。濃
縮缶液２からの蒸発が進行し、ミストセパレータ３を通
過して凝縮器８で凝縮し始めた時点で、原料硝酸タンク
６から模擬硝酸廃液を２Ｑ／ｈで連続供給し、濃縮缶１
からの蒸発量もヒータ加熱用電源５の調節により同量と
なるよう運転した。濃縮缶１から蒸発した水および硝酸
ガスは、凝縮器８で凝縮したのち、硝酸精製装置１１で
さらに精製され、回収水１２と回収硝Ｎ！１３に分離し
た。本運転モードにより濃縮缶液２では、放射性核種を
模擬した金属イオン濃度が直線的に増加し、それと同時
に硝酸濃度は、第２図に示したごとく増加し、１０規定
と
をヒータ℃で減少に転じ、金属イオンの濃縮度（ＩＡ縮
缶中濃度／供給液中濃度）が２０となった時点で７規定
となった。An embodiment of the present invention will be described with reference to FIG. The figure shows a vacuum concentration system for high-level nitric acid waste liquid containing a large amount of radionuclides, but in the following examples, results using simulated waste liquid will be mainly described. 20Q in advance into nitric acid concentration can 1
Put in a simulated waste solution that simulates the nitric acid waste solution. The simulated waste liquid is made by dissolving stable elements, which are the same as radionuclides but do not have radioactivity, in nitric acid.There are 30 types of elements such as cesium, barium, and ruthenium, and their concentrations are The average value in the treatment process was set to 0.05 moQ/Q for all elements, and the nitric acid concentration was set to 3.2 normal. The concentrated liquid 2 in the concentrated can is heated by a heater 4 connected to a heater power source 5. Further, the concentration system was constantly depressurized to 50 Torr using a vacuum exhaust device 10. When the evaporation from the concentrated can liquid 2 progresses and it passes through the mist separator 3 and begins to condense in the condenser 8, simulated nitric acid waste liquid is continuously supplied from the raw nitric acid tank 6 at a rate of 2Q/h, and the concentrated can 1
The operation was performed so that the amount of evaporation from the heater was also the same by adjusting the heater heating power source 5. The water and nitric acid gas evaporated from the concentrator 1 are condensed in the condenser 8 and then further purified in the nitric acid purifier 11 to produce recovered water 12 and recovered nitrate N! It was separated into 13 parts. In this operation mode, the concentration of metal ions simulating radionuclides increases linearly in the concentrate liquid 2, and at the same time, the nitric acid concentration increases as shown in Figure 2, and decreases from 10N with heating temperature. When the concentration of metal ions (concentration in IA condenser/concentration in feed liquid) reached 20, it became 7N.
比較例として、先ず、この時点で模擬硝酸廃液の供給を
停止し、供給水タンク１４から濃縮缶１中に水を２Ｑ／
ｈで供給した。運転条件は、水供給前と全く同条件で運
転した。これによると、第３図に示すごとく、濃縮缶液
２の硝酸濃度は減少した。７規定から５規定までは約１
日であるが、５規定から３規定までは約９日を要したが
、濃縮缶液中の金属イオン濃度を変えることなく硝酸濃
度を７規定から３規定に低減された。As a comparative example, first, at this point, the supply of the simulated nitric acid waste liquid was stopped, and water was poured into the concentrator 1 from the supply water tank 14 for 2Q/2 hours.
It was supplied at h. The operating conditions were exactly the same as before water supply. According to this, as shown in FIG. 3, the nitric acid concentration of the concentrated can liquid 2 decreased. From 7th regulation to 5th regulation is approximately 1
However, it took about 9 days to go from 5N to 3N, but the nitric acid concentration was reduced from 7N to 3N without changing the metal ion concentration in the concentrate.
本発明の実施例１では、模擬硝酸廃液の濃縮までは、上
述の比較例１と同一操作を実施したのち、供給水タンク
１４から水を２＋１／ｈで供給し、濃縮缶液２中硝酸濃
度を５規定まで低下させた。その後、アルカリ性水溶液
タンク１５からアルカリ性水溶液を水の代わりに２Ｑ／
ｈ供給した。アルカリ性水溶液はエチルアミンの０．３
ｍｏＲ／Ｑ水溶液を使用したが、第３図に示すごとくに
、濃縮缶液２中の硝酸濃度の低減速度が加速され、約３
日後には３規定となった。アルカリ性水溶液としては、
メチルアミン、ブチルアミン、エチレンジアミン、ヘキ
シルアミン等の強アルカリ性の脂肪族アミンであればな
んでもよい。ただし、濃縮の操作温度の範囲（５０〜６
０℃）で蒸発するものは避けた方がよい。ただし、この
中和反応は極めて速いため、通常は蒸発前に中和されて
安定化する。本実施例で得られた３規定の濃縮硝酸廃液
の一部をとり、加熱炉でガラス固化温度まで加熱したと
ころ、残留物は放射性核種の模擬物として使用した金属
イオンの酸化物および硝酸塩のみであり、硝酸および添
加したアミンは全て分解ガスとなることが確認できた。In Example 1 of the present invention, up to the concentration of the simulated nitric acid waste liquid, the same operation as in Comparative Example 1 described above was carried out, and then water was supplied from the supply water tank 14 at a rate of 2+1/h, and the nitric acid concentration in the concentrated canned liquid 2 was was lowered to 5 regulations. After that, add 2Q/alkaline solution from the alkaline solution tank 15 instead of water.
h was supplied. The alkaline aqueous solution is 0.3 of ethylamine.
Although the moR/Q aqueous solution was used, as shown in Fig. 3, the rate of decrease in the nitric acid concentration in the concentrate 2 was accelerated, and the rate of decrease was approximately 3
A day later, there were three regulations. As an alkaline aqueous solution,
Any strong alkaline aliphatic amine such as methylamine, butylamine, ethylenediamine, hexylamine etc. may be used. However, the operating temperature range for concentration (50 to 6
It is best to avoid substances that evaporate at temperatures (0°C). However, since this neutralization reaction is extremely fast, it is usually neutralized and stabilized before evaporation. When a part of the 3N concentrated nitric acid waste liquid obtained in this example was taken and heated to the vitrification temperature in a heating furnace, the residue was only oxides and nitrates of the metal ions used as radionuclide simulators. It was confirmed that all of the nitric acid and the added amine turned into decomposed gas.
比較例２は、模擬硝酸廃液の濃縮までは比較例１と同様
に操作し、その後の水の供給量を４Ｑ／ｈとした。この
場合、蒸発量も同量となるようなヒータ４の加熱量を増
加させた。これによると、硝酸濃度が３規定に達するの
に約５日となり、比較例１よりも半減した。しかし、こ
れを実施するには、ヒータ４の加熱容量および凝縮器８
の凝縮性能に十分なる余裕がある場合に可能となる。Comparative Example 2 was operated in the same manner as Comparative Example 1 up to the concentration of the simulated nitric acid waste solution, and the amount of water supplied thereafter was 4 Q/h. In this case, the heating amount of the heater 4 was increased so that the amount of evaporation was also the same. According to this, it took about 5 days for the nitric acid concentration to reach 3N, which was half that of Comparative Example 1. However, to implement this, the heating capacity of the heater 4 and the condenser 8
This is possible if there is sufficient margin for condensation performance.
本発明の実施例２は、比較例２中の水の供給をアルカリ
水溶液に代えた場合である。比較例２中で、水供給によ
り濃縮缶内硝酸濃度が５規定となった時点で、アルカリ
水溶液に代えた。供給量は４ｕ／ｈであり、アルカリ水
溶液の成分は実施例１と同一とした。これによると、濃
縮缶内硝酸濃度は、約１．５ 日で３規定まで低減した
。Example 2 of the present invention is a case where the supply of water in Comparative Example 2 was replaced with an alkaline aqueous solution. In Comparative Example 2, when the concentration of nitric acid in the concentrator reached 5N by supplying water, the aqueous alkaline solution was substituted. The feed rate was 4 u/h, and the components of the alkaline aqueous solution were the same as in Example 1. According to this, the nitric acid concentration in the concentrate tank decreased to 3N in about 1.5 days.
上記実施例１および２ともに当初水を供給し、その後に
熱分解性アルカリ性水溶液を供給する場合を示したが、
当初から該アルカリ水溶液を供給してもよい。ただし、
当初は水とアルカリとで硝酸濃度低減効果にほとんど差
異はないため、アルカリ使用量を低減させる点から、当
初は水を供給するのが望ましい。In both Examples 1 and 2 above, water is initially supplied and then a pyrolyzable alkaline aqueous solution is supplied.
The alkaline aqueous solution may be supplied from the beginning. however,
Initially, there is almost no difference in the effect of reducing nitric acid concentration between water and alkali, so it is desirable to supply water initially from the viewpoint of reducing the amount of alkali used.
本発明によれば、放射性核種を多量に含む硝酸廃液を蒸
発濃縮したのちの廃液の硝酸濃度を、簡略な手法でかつ
短時間にできるため、濃縮廃液タンクの腐食に対する耐
久性を大幅に向上できる。According to the present invention, the nitric acid concentration in the waste liquid after evaporating and concentrating the nitric acid waste liquid containing a large amount of radionuclides can be reduced by a simple method and in a short time, so that the durability against corrosion of the concentrated waste liquid tank can be greatly improved. .
この結果、機器寿命の増進および機器の保守点検工数が
１７２以下に低減可能である。As a result, it is possible to extend the life of the equipment and reduce the number of man-hours for maintenance and inspection of the equipment to 172 or less.
第１図は本発明の一実施例のシステムフロー図、第２図
は減圧濃縮操作時の蒸発缶内硝酸濃度の変化図、第３図
は水およびアルカリ水溶液添加時の蒸発缶内硝酸濃度の
変化図である。
１・・・硝酸濃縮缶、２・・・濃縮缶液、３・・・ミス
トセパレータ、４・・・ヒータ、５・・・ヒータ用電源
、６・・・原料硝酸タンク、７・・・濃縮廃液タンク、
８・・・凝縮器、９・・・冷却水循環装置、１０・・・
真空排気装置、１１・・・硝酸精製装置、１２・・・回
収水タンク、１３・・・回収硝酸タンク、１４・・・供
給タンク、１５・・・アルカリ性水溶液タンク。Figure 1 is a system flow diagram of an embodiment of the present invention, Figure 2 is a diagram of changes in nitric acid concentration in the evaporator during vacuum concentration operation, and Figure 3 is a diagram of changes in nitric acid concentration in the evaporator when water and aqueous alkaline solutions are added. This is a diagram of changes. 1... Nitric acid concentration can, 2... Concentrated can liquid, 3... Mist separator, 4... Heater, 5... Power supply for heater, 6... Raw material nitric acid tank, 7... Concentration waste liquid tank,
8... Condenser, 9... Cooling water circulation device, 10...
Vacuum exhaust device, 11... Nitric acid purification device, 12... Recovered water tank, 13... Recovered nitric acid tank, 14... Supply tank, 15... Alkaline aqueous solution tank.
Claims (1)
いて、濃縮後の硝酸廃液の硝酸濃度を熱分解性アルカリ
性水溶液を供給しながら、加熱による蒸発操作を実施す
ることで低下させることを特徴とする硝酸廃液の濃縮方
法。 ２、特許請求の範囲第１項において、濃縮後の硝酸廃液
に先ず水を供給したのち、熱分解性アルカリ性水溶液を
供給するものであつて、該アルカリ水溶液を供給する時
点は水とアルカリとで硝酸濃度低下能力に差異を生じる
時点近傍である硝酸廃液の濃縮方法。 ３、特許請求の範囲第１項または第２項記載の熱分解性
アルカリ性水溶液は脂肪族アミンもしくはアンモニア水
もしくはそれらの混合物である硝酸廃液の濃縮方法。[Claims] 1. In a method of evaporating and concentrating a nitric acid waste solution containing radionuclides, the nitric acid concentration of the nitric acid waste solution after concentration is reduced by performing an evaporation operation by heating while supplying a pyrolytic alkaline aqueous solution. A method for concentrating nitric acid waste liquid, characterized by: 2. In claim 1, water is first supplied to the concentrated nitric acid waste liquid, and then a pyrolyzable alkaline aqueous solution is supplied, and the point at which the alkaline aqueous solution is supplied is when water and alkali are mixed together. A method for concentrating nitric acid waste liquid, which is close to the point at which a difference occurs in the ability to reduce nitric acid concentration. 3. A method for concentrating nitric acid waste liquid, wherein the thermally decomposable alkaline aqueous solution according to claim 1 or 2 is an aliphatic amine, aqueous ammonia, or a mixture thereof.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62273778A JP2610453B2 (en) | 1987-10-29 | 1987-10-29 | Concentration method of nitric acid waste liquid |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62273778A JP2610453B2 (en) | 1987-10-29 | 1987-10-29 | Concentration method of nitric acid waste liquid |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH01114799A true JPH01114799A (en) | 1989-05-08 |
| JP2610453B2 JP2610453B2 (en) | 1997-05-14 |
Family
ID=17532444
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62273778A Expired - Fee Related JP2610453B2 (en) | 1987-10-29 | 1987-10-29 | Concentration method of nitric acid waste liquid |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2610453B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009244089A (en) * | 2008-03-31 | 2009-10-22 | Toden Kogyo Co Ltd | Removing method and removing device of radioactive material and toc |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5516300A (en) * | 1978-07-17 | 1980-02-04 | Kernforschungsanlage Juelich | Waste processing method starting from fission product solution * and device therefor |
| JPS6219796A (en) * | 1985-07-19 | 1987-01-28 | 東洋エンジニアリング株式会社 | Method of solidifying and treating radioactive liquid |
-
1987
- 1987-10-29 JP JP62273778A patent/JP2610453B2/en not_active Expired - Fee Related
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5516300A (en) * | 1978-07-17 | 1980-02-04 | Kernforschungsanlage Juelich | Waste processing method starting from fission product solution * and device therefor |
| JPS6219796A (en) * | 1985-07-19 | 1987-01-28 | 東洋エンジニアリング株式会社 | Method of solidifying and treating radioactive liquid |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2009244089A (en) * | 2008-03-31 | 2009-10-22 | Toden Kogyo Co Ltd | Removing method and removing device of radioactive material and toc |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2610453B2 (en) | 1997-05-14 |
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Legal Events
| Date | Code | Title | Description |
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| LAPS | Cancellation because of no payment of annual fees |