阅读说明：本技术 一种小型核设施退役现场放射性废水处理方法 (Method for treating radioactive wastewater of retired field of small nuclear facility ) 是由 王永仙 梁栋 郭丽潇 邓少刚 张文俊 武明亮 梁宇 刘�东 高亚华 张宇航 高志 于 2020-04-30 设计创作，主要内容包括：本发明公开了一种小型核设施退役现场放射性废水处理方法。所述方法包括絮凝沉淀、两级蒸发冷凝、冷凝水净化、固体废物处理等步骤。本发明所提供的方法可以安全、高效地处理小型核设施退役现场的放射性废水,且产生的二次放射性废物较少、易于处置。(The invention discloses a method for treating radioactive wastewater in a decommissioning site of a small nuclear facility. The method comprises the steps of flocculation precipitation, two-stage evaporation and condensation, condensed water purification, solid waste treatment and the like. The method provided by the invention can safely and efficiently treat the radioactive wastewater of the decommissioned site of the small nuclear facility, and the generated secondary radioactive waste is less and easy to treat.)

1. A method for treating radioactive wastewater in a decommissioned site of a small nuclear facility is characterized by comprising the following steps:

step (1), radioactive wastewater generated by decommissioning of a small nuclear facility is discharged into a chemical flocculation precipitation tank, a certain amount of chemical flocculant is firstly added into the tank, then a certain amount of coagulant aid is added, finally, an antifoaming agent is added, the mixture is stirred and then stands still, flocculate is generated in the waste liquid, and the flocculate and the impurities are precipitated to the bottom of the precipitation tank;

step (2), opening a control valve of the precipitation tank to enable supernatant in the precipitation tank to be conveyed to a primary evaporation container through the control valve, opening a far infrared heating device above the primary evaporation container when the liquid in the primary evaporation container reaches more than half of the volume of the container, and adjusting the distance between the far infrared heating device and the primary evaporation container and the temperature of the far infrared heating device to evaporate the liquid in the container; the concentrated water formed by primary evaporation flows back to the precipitation tank, the generated water vapor is filtered by the wire mesh demister at the outlet, reaches the matched primary condenser, is condensed into liquid and flows into the secondary evaporation container;

step (3), after the liquid in the secondary evaporation container exceeds half of the container volume, starting a far infrared heating device above the secondary evaporation container, adjusting the distance between the far infrared heating device and the secondary evaporation container and the temperature of the far infrared heating device, starting secondary evaporation, enabling concentrated water formed by the secondary evaporation to flow back to the primary evaporation container, and enabling generated steam to reach an ion exchange column after being condensed by a secondary condenser;

purifying the secondary condensate water by an ion exchange column, loading small-particle silver zeolite and ion exchange resin in the ion exchange column, storing the purified water in a water purification tank, and discharging the purified water after the purified water is qualified through periodic sampling detection;

and (5) after the sludge and the impurities generated in the chemical flocculation precipitation tank are precipitated to a certain amount, discharging to a waste drying container, carrying out microwave drying in the container, wherein the microwaves uniformly act on the moisture in the sludge to enable the moisture to become water vapor, the water vapor is converged into a steam channel of the primary evaporation container, and the formed dry radioactive waste is periodically discharged into a waste barrel.

2. The method for treating radioactive wastewater in the decommissioned site of a small-sized nuclear facility according to claim 1, wherein the flocculating agent in the step (1) is one or more of aluminum potassium sulfate, sodium aluminate, ferric sulfate and ferric chloride.

3. The method for treating radioactive wastewater in the decommissioned site of a small nuclear facility according to claim 1, wherein the coagulant aid in the step (1) is one or more of activated silica, clay and polyelectrolyte.

4. The method for treating radioactive wastewater in the decommissioned site of a small nuclear facility according to claim 1, wherein the antifoaming agent in step (1) is monoamide or lauric acid.

5. The method for treating radioactive wastewater in the decommissioned site of a small nuclear facility as claimed in claim 1, wherein the spent zeolite and ion exchange resin in the ion exchange column in the step (4) are discharged to a waste drying container through a discharge valve, subjected to microwave drying and discharged to a waste bucket.

6. The method for treating radioactive wastewater in the decommissioned site of a small nuclear facility as claimed in claim 1, wherein in the step (2), the distance between the far infrared heating device and the secondary evaporation container is 5-10mm, and the temperature of the far infrared heating device is 120-140 ℃.

7. The method for treating radioactive wastewater in the decommissioned site of a small nuclear facility as claimed in claim 1, wherein in the step (2), the distance between the far infrared heating device and the secondary evaporation container is 5-10mm, and the temperature of the far infrared heating device is 120-140 ℃.

Technical Field

The invention relates to the field of radioactive wastewater treatment in the field of radioactive three-waste treatment, in particular to a method for treating radioactive wastewater in a decommissioning site of a small nuclear facility.

Background

A large amount of radioactive wastewater is generated in the processes of nuclear fuel production, nuclear power plant operation, isotope production and use, nuclear facility decommissioning and the like, and the radioactive wastewater generated in different nuclear facilities and different operation stages has very different properties and needs to be treated by different processes and devices. The invention mainly aims at radioactive waste water generated in the decommissioning process of small nuclear facilities (the small nuclear facilities refer to small-area nuclear facilities such as radioactive laboratories, miniature reactors and the like), and the waste water has the following characteristics:

1) the radioactive waste water yield is small. Daily production is generally less than 50L.

2) The source is complex and the source item is complex. According to experience, the decommissioned radioactive wastewater of a small nuclear facility comes from a complex source, including a little unidentified liquid remaining in a container in the facility, wastewater generated by field decontamination, wastewater generated by hand washing of personnel, and the like. Often containing more than one radionuclide. The liquid usually contains a small amount of organic waste liquid, such as alcohol, engine oil, surfactant, etc.

3) High impurity content and high solid content. The waste water generated by the decommissioning of the small nuclear facilities often contains a small amount of rust slag, stones, gravels, sludge, and even impurities such as branches and leaves.

The small nuclear facility decommissioning site has the characteristics that:

1) generally has no waste liquid treatment capacity, but has certain solid waste storage capacity.

2) The field space is limited, and the large-scale equipment is not suitable for being unfolded.

3) For the treatment of a small amount of waste water, the energy-saving requirement can be properly relaxed.

Aiming at the characteristics of the decommissioning site of the small nuclear facility and the water quality characteristics of the radioactive wastewater generated in the decommissioning process, a radioactive wastewater treatment method suitable for the decommissioning site of the small nuclear facility needs to be developed so as to safely and efficiently treat the radioactive wastewater in the decommissioning site and reduce secondary radioactive wastes generated in the treatment process as much as possible.

Disclosure of Invention

In view of the defects in the prior art, the invention aims to provide a method for treating radioactive wastewater in a decommissioned site of a small nuclear facility, which can safely and efficiently treat the radioactive wastewater in the decommissioned site, generates less secondary radioactive wastes and is easy to treat.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a method for treating radioactive wastewater in a decommissioned site of a small nuclear facility comprises the following steps:

step (1), radioactive wastewater generated by decommissioning of a small nuclear facility is discharged into a chemical flocculation precipitation tank, a certain amount of chemical flocculant is firstly added into the tank, then a certain amount of coagulant aid is added, finally, an antifoaming agent is added, the mixture is stirred and then stands still, flocculate is generated in the waste liquid, and the flocculate and the impurities are precipitated to the bottom of the precipitation tank;

step (2), opening a control valve of the precipitation tank to enable supernatant in the precipitation tank to be conveyed to a primary evaporation container through the control valve, opening a far infrared heating device above the primary evaporation container when the liquid in the primary evaporation container reaches more than half of the volume of the container, and adjusting the distance between the far infrared heating device and the primary evaporation container and the temperature of the far infrared heating device to evaporate the liquid in the container; the concentrated water formed by primary evaporation flows back to the precipitation tank, the generated water vapor is filtered by the wire mesh demister at the outlet, reaches the matched primary condenser, is condensed into liquid and flows into the secondary evaporation container;

step (3), after the liquid in the secondary evaporation container exceeds half of the container volume, starting a far infrared heating device above the secondary evaporation container, adjusting the distance between the far infrared heating device and the secondary evaporation container and the temperature of the far infrared heating device, starting secondary evaporation, enabling concentrated water formed by the secondary evaporation to flow back to the primary evaporation container, and enabling generated steam to reach an ion exchange column after being condensed by a secondary condenser;

purifying the secondary condensate water by an ion exchange column, loading small-particle silver zeolite and ion exchange resin in the ion exchange column, storing the purified water in a water purification tank, and discharging the purified water after the purified water is qualified through periodic sampling detection;

and (5) after the sludge and the impurities generated in the chemical flocculation precipitation tank are precipitated to a certain amount, discharging to a waste drying container, carrying out microwave drying in the container, wherein the microwaves uniformly act on the moisture in the sludge to enable the moisture to become water vapor, the water vapor is converged into a steam channel of the primary evaporation container, and the formed dry radioactive waste is periodically discharged into a waste barrel.

Further, the flocculating agent in the step (1) is one or more of aluminum potassium sulfate, sodium aluminate, ferric sulfate and ferric chloride.

Further, the coagulant aid in the step (1) is one or more of active silica, clay and polyelectrolyte.

Further, the defoaming agent in the step (1) is monoamide or lauric acid.

And (3) further, discharging the deactivated zeolite and the ion exchange resin in the ion exchange column in the step (4) to a waste drying container through a discharge valve, performing microwave drying, and discharging into a waste barrel.

Further, in the step (2), the distance between the far infrared heating device and the secondary evaporation container is 5-10mm, and the temperature of the far infrared heating device is 120-140 ℃.

Further, in the step (2), the distance between the far infrared heating device and the secondary evaporation container is 5-10mm, and the temperature of the far infrared heating device is 120-140 ℃.

The invention has the beneficial effects that:

1) the invention is particularly suitable for treating radioactive wastewater with high solid content and impurity content; after the radioactive wastewater combined treatment process is finished, a waste drying process is combined to realize the drying treatment of the wet waste generated in the wastewater treatment process;

2) the whole process of waste liquid treatment does not generate secondary liquid waste, and the generated waste is dry solid waste;

3) the waste liquid is heated by adopting a container external far infrared heating mode, and meanwhile, the heating device is ensured not to be polluted by radioactive waste liquid or steam, so that secondary waste is reduced;

4) the adoption of the microwave heating mode outside the container realizes heating and drying of the wet waste, and simultaneously ensures that a heating device is not polluted by radioactive waste liquid or steam, thereby reducing secondary waste.

Drawings

FIG. 1 is a schematic view of a radioactive wastewater treatment process according to an embodiment of the present invention.

Detailed Description

The invention is described in further detail below with reference to the drawings and the detailed description.