JPS618700A - Incinerating treating device for radioactive waste - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is particularly capable of incinerating radioactive waste such as the counting duplex used in the measurement of '29■. 12ゝI in the generated combustion exhaust
This invention relates to a radioactive waste incineration treatment device that can continuously measure and monitor the concentration of radioactive waste.

[Conventional technology]

Recently, liquid radioisotopes containing unsealed radioactive materials (
It is well known that RI (hereinafter simply referred to as RI) has come to be actively used in research and medical fields, and in particular, labeled compounds using 3 H and 12-hydroxylated compounds are used extremely frequently.

This trend is particularly noticeable in the fields of medical treatment and research, and the radioactive waste generated as a result is extremely large, posing a serious problem. for example,
In Japan alone, the number of counting tubes (hereinafter simply referred to as tubes) used to measure one count reaches several thousand five a year, and the amount of counting tubes (hereinafter simply referred to as tubes) used to measure one count reaches several thousand five each year. The amount of radioactive organic scintillator waste liquid (hereinafter simply referred to as waste liquid) amounts to several tens of tons per year, and on a global level, the amount is impossible to estimate.

In view of the above-mentioned circumstances, the inventor of the present invention has completed the development of a technology that enables incineration of the waste liquid by subjecting it to special pretreatment, and has already received a patent for it (Japanese Patent Publication No. 57-32798). Although we have reached the stage where incineration of waste liquid using this technology is being carried out safely and efficiently at many industrial sites in Japan, it is difficult to incinerate other radioactive waste, especially the tubes mentioned above. 1 for incineration of
Problems remain.

[Problem that the invention seeks to solve]

First, the tube to be incinerated is made of polyethylene, polystyrene, etc.
The tube is made of a resin with a high calorific value of up to 1.5 kg/kg, and as environmental hygiene standards have become stricter in recent years, it is necessary to incinerate the tube using a material that can withstand such high temperatures and prevents pollution. Although there is a need for a device that does not generate waste, an incineration device that satisfies these conditions has not been provided.

The second difficulty is that no system has been established for safely handling the tubes using (1) as in the case of waste liquids.

Therefore, its half-life is shorter at 60.2 days compared to 1.2.33 years for H, and theoretically the strength of radioactivity would decrease to 1 in about 2 years.
Although it is considered possible to incinerate the tube after it decays to 1,000%, the reason why no treatment technology has been established for the tube is that the radioactive isotope 2ゞ■ Since the energy of the radiation emitted by electron capture (EC) is as low as approximately 35 KeV, it is not possible to use conventional detectors and detection methods for detecting gamma rays and Z rays. This is thought to be due to the fact that there was no means to confirm the attenuation of .

On the other hand, in case (2), it is difficult to ensure radiation safety even at the stage of workers handling the radiation, and it is believed that ingestion from contaminated hands or fingers, etc., caused thyroid accumulation without realizing it. It is a far more dangerous nuclide than 3H in that it has been reported both domestically and internationally, and even if a system for safely handling tubes contaminated with 12I is completed, The concentration of attached I114 varies, and it is expected that there will be extremely high concentrations of I, such as tubes used for radioionization. Measure and monitor the concentration of ■121 due to incorrect handling before incineration.
It is necessary to prevent the release of The present invention was completed as a result of intensive research to solve the above-mentioned difficulties.

[Means for solving problems]

To this end, the measures taken by the present invention include an incinerator equipped with a cooling system to improve heat resistance, an air supply system for supplying excess oxygen to the inside, and an incinerator for incineration of radioactive waste. and a measurement device that measures the concentration of radioisotopes in the combustion exhaust by guiding a portion of the combustion exhaust discharged from the incinerator to a suitable adsorbent and detecting and measuring radiation in the adsorption material. It is characterized by Koya.

〔Example〕

Next, an example of implementation of the present invention will be explained with reference to the drawings.

1 is an incinerator, and as mentioned above, the incinerator 1 has tubes to be incinerated made of polyethylene, polystyrene, etc.
Since these resins have a high calorific value of 0OOKcLIL/kg, in order to incinerate them, first, 1,000
It was constructed to withstand high temperatures up to 0°C.

In other words, the structure of the incinerator 1 is a double structure consisting of the inner and outer copper plates 2 and 3, and by using a water cooling jacket method filled with cooling water W between them, all parts that are exposed to the flame are indirectly cooled by the cooling water W. Thermal energy is guided to the outside in this way. In addition, use this warm water in the bath 1. If used in showers, etc., thermal energy can be used effectively. It is also necessary that there is no pollution caused by black smoke, and although complete combustion of polyethylene is easy, some tubes are made of flame-retardant resin such as polystyrene, so such tubes In order to completely incinerate the waste, an air supply device 4 such as a high-pressure turbo fan supplies an equal amount of excess air with equal pressure to the entire furnace through numerous nozzles 5 with minute diameters, thereby preventing a drop in the temperature inside the furnace. At the same time, excess oxygen was supplied for complete combustion.

On the other hand, all of the nozzles 5 are arranged in the double structure to protect them from high heat so that they will not be damaged. Also, with this structure, the air supplied into the incinerator 1 is preheated. This results in a further improvement in combustion efficiency.

In addition, 6 prevents soot and dust from being emitted from the chimney 7, and meets the soot and dust regulation value (0.4, g/Nm) regulated by the Air Pollution Control Act and each prefectural pollution control ordinance. A tangential flow type cyclone dust collector is inserted between the incinerator 1 and the chimney 7 to lower the dust.

Furthermore, as a structure attached to the incinerator 1, in addition to the above-mentioned structures, a cooling water abnormality alarm display device, a seismic device, and a combustion stop mechanism (none of which are shown) may be provided as safety measures. .

On the other hand, 8 is in front. A part of the combustion exhaust gas is taken from the intake hole 9 drilled in a part of the chimney 7, and the concentration of +Zr in the combustion exhaust is measured, and the value is displayed on the display/recording device 10. This is a measuring device for recording on the recording paper 12, and as mentioned above, it has been extremely difficult to measure 125''N in the past, but the inventor of the present invention independently developed it and has already filed a patent application. This problem has been solved by using technology related to low-level 72-wire scintillation survey meters.

That is, this scintillation survey meter has its scintillation section C as shown in FIG. It is composed of a scintillator S made by Pyrex and an optical window P made of Pyrex, and the entrance window is made of 150 μm beryllium, which has excellent radiation transparency and can transmit not only high-energy radiation but also low-energy radiation without absorbing it. By using a thin plate, transparency for low-energy radiation is ensured, and by considering the shape of the scintillator S, and making it a relatively thin plate,
While reducing the amount of radiation incident from the side, the entrance window I
Of the radiation that has passed through it, high-energy radiation is transmitted to suppress the scintillation phenomenon, while low-energy radiation is absorbed to almost completely cause scintillation, and the counting efficiency for 12゜■ is approximately 25. %, which is approximately 250 times more sensitive than a conventional forceps survey meter, and is used to measure 12°I in combustion exhaust gas.

Furthermore, even if the scintillation part C of the low-energy Baymeter is used to directly measure the 125 concentration in the combustion exhaust, the maximum permissible 125 concentration in the exhaust gas is extremely strict. Since direct measurement in a flowing state is impossible, the concentration of 11 in the combustion exhaust gas can be measured by collecting 1 with an appropriate +1 adsorbent and measuring 1'''ゞI in the adsorbent. Activated carbon filters conventionally used for such purposes are made by solidifying powder such as activated carbon from coconut into a plate shape, so the activated carbon powder tends to scatter and damage the suction pump. In order to carry out continuous long-term measurements, it is preferable to form the belt into a belt and use it in static motion, but this conventional product does not have the strength to stretch and breaks, so it must be replaced at regular intervals as a cartridge. Therefore, in the present invention, activated carbon fibers are suitable for continuous collection of 12゜I for long periods of time because they are strong, do not scatter powder, and do not tear even when made into a belt. A filter (hereinafter referred to as ACFF) was used as the adsorbent.

To explain in detail with reference to FIG. 1, 13 is a ventilation pipe, 14 is
15 is a suction pump, 15 is an ACFF wound between a pair of rollers 16 and 17 and inserted between the ventilation pipe 13 and the suction pump 14, and 18 is a controller 1 to a roller for rotating one roller 17. , 19 is a lead shield body 20
This detector employs the scintillation section C disposed in the AC.
After a certain period of time has elapsed, the controller 18 rotates one roller 17 in response to a command signal from the measurement display unit 10, and the ACFF, which had been exposed to combustion exhaust until then, is attracted to the corresponding part of the ACFF 5. The portion 2 moves to the lower part of the detector 19, and the amount 2 is detected and output to the display measurement section 10.

The temperature of the exhaust air in the air sampling hole 9 is also close to 300°C, and if the air is sucked in as it is, damage will occur to the ACFF 15, etc., so for example, an electronic cooler 21 is installed in the middle of the ventilation pipe 13.
The suction pump 14 is controlled by the measurement display unit 10 to adjust the face velocity of the combustion exhaust in the ACFF 15, which is determined by the current velocity meter 22. 1 to 22 constitute an example of the device of the present invention.

[For production]

An example of the device of the present invention configured as described above includes 1211
When a tube T contaminated with water is thrown in and ignited, the tube T first liquefies, then vaporizes and begins to burn. At this time, excess oxygen is supplied from the nozzle 5, and the heat generated by combustion Since the energy is absorbed by the cooling water W, the tube T can be removed without damaging the incinerator 1.
is now completely combusted.

In addition, the combustion exhaust is discharged from the chimney 7 after dust etc. are removed by the cyclone dust collector 6, but a part of it is sucked into the 1L measuring device 8 through the intake hole 9 and is converted into the ACF.
Continuous measurements using F are performed, and the results are displayed and recorded by the display/recording device IO.

〔effect〕

Therefore, according to an example of the apparatus of the present invention, the tube that generates high thermal energy can be completely incinerated without damaging the incinerator or emitting dust, etc. This makes it possible to continuously measure and monitor 12°I contained in combustion exhaust gas.

Therefore, 11 to be incinerated by an example of the apparatus of the present invention
Tubes contaminated with 5■ do not start incineration simply because a certain period of time (for example, about 2 years) has passed, but use the scintillation laser paymeter for low-level gamma rays to determine the actual dose. Of course, you should confirm that the material is suitable for incineration before handling it, but in order to further increase safety, handle it as follows.

That is, the tube is as shown in FIG.

An appropriate number of plastic bags V are placed, and the two bags are sealed and stored in a cylindrical drum with a resistance of 50Ω. By inserting an adsorbent into the adsorbent and allowing the adsorbent to collect the iodine gas constantly generated by radioactive autolysis of the labeled compound, and measuring the adsorbent with the survey meter, the tubes inside the drum, including those at the bottom, can be collected. For example, 0.1 μCi of Pm-147
By placing a sealed radiation source with a half-life of 2.6234 years on the lid of a drum and measuring its attenuation rate with a GM-survey meter or low-energy gamma-ray survey meter, it is possible to ensure that a certain period of time has elapsed. The purpose is to make sure that the

[Other Examples]

In an incinerator like the above-mentioned example of the present invention, it may be better to preheat the inside of the incinerator before starting incineration.
In this case, city gas, propane gas, kerosene, etc. may be used for preheating by adding a known configuration.

For example, when using kerosene, the kerosene stored in the preheating tank 23 is poured into the solenoid valve 24. The kerosene is supplied to an electromagnetic pump 27 via a flow meter 25 and a filter 26, and the electromagnetic pump 27 forces the kerosene to a nozzle 28 whose tip faces into the incinerator 1. The kerosene is sprayed from the tip of the nozzle 28 and ignited. The igniter 30 is operated by the transformer 29 to ignite the sprayed kerosene, and while the burner motor 31 is operated, combustion is performed for preheating.

In addition, since the above-mentioned waste liquid has an organic solvent as its main component, it can of course be used as a fuel for preheating, but the composition of the waste liquid is generally unknown and often has a high viscosity.
Since it is not suitable for spraying from the nozzle 28, it is not suitable for direct combustion.
It shall be pretreated by techniques such as those disclosed in No.

Therefore, the fact that the waste liquid can be used for preheating also means that the tube and the waste liquid can be incinerated at the same time if a configuration for this purpose is added to the apparatus of the present invention. However, in this case, substances that are difficult to vaporize, such as surfactants and naphthalene, remain in the nozzle 28 after incineration and clog the nozzle 28, so a waste liquid tank provided separately from the tank 23 is used to store the waste liquid. 32, first burn the kerosene in the tank 23 to clean the inside of the pipes and preheat the inside of the incinerator 1, and then open the solenoid valve 24.
33 to incinerate the waste liquid in the waste liquid tank 32, and when the incineration is finished, switch the solenoid valves 24 and 33 again to circulate the kerosene in the pipe and incinerate it without leaving any components that could clog the nozzle 28. be.

If the inside of the pipes is cleaned by storing only kerosene in the tank 23, the nozzle may be sintered due to the surfactant, so do not add an auxiliary agent such as n-butanol to the kerosene. Kerosene according to the inventor of the present invention may also be added:
It has been found that best results are obtained with n-butanol-1:1.

[For production]

The procedure for separately incinerating radioactive waste using the apparatus of the present invention with such a configuration is as follows: (1) Approximately 10 kg of used tubes are placed in the incinerator 1, and kerosene and waste liquid are placed in the tank 23. The tank 32 stores waste liquid.

(2) When the incineration switch is pressed, air is blown out from the nozzle 5 to expel the gas in the incinerator 1 and prevent an explosion when ignited (breapage).

(3) Prior to incineration of waste liquid, a mixture of kerosene and n-butanol is sprayed from the tank 23 into the incinerator 1 by the electromagnetic pump 27, and ignited and burned by the ignition transformer 29 and igniter 30 to preheat it.

(4) When the temperature inside the furnace rises after several minutes, the solenoid valves 24 and 33 are automatically switched, and the waste liquid in the tank 32 begins to be incinerated (the waste liquid is incinerated at a rate of 2Q per hour).

(5) As the waste liquid incineration progresses, the tube T at the bottom of the incinerator 1 is dissolved, liquefied and gasified, and combustion begins.

(6) When the incineration is finished, the solenoid valves 24 and 33 are automatically switched, and the waste liquid is changed to a mixture of kerosene and n-butanol, which cleans the nozzle 27, electromagnetic pump 27, waste liquid in the pipes, etc. The cleaning liquid is incinerated (stock cleaning incineration).

(7) When cleaning and incineration are completed, the solenoid valve 24.33
When the electromagnetic pump 27 closes, the electromagnetic pump 27 stops, but the air injection from the nozzle 5 continues for several minutes to exhaust the residual gas in the incinerator 1 (after purge).

[Effect] Conventionally, waste liquids, etc. were incinerated using a so-called dedicated incinerator, so if we adopt a co-incineration method in which the tube and waste liquid are incinerated at the same time, the waste liquid will be burned at the same time as the tube is incinerated, and the incineration will be completed. It is effective in preventing a drop in temperature and stably sustaining complete combustion.Also, depending on the components of the waste liquid, there are cases where it is difficult to incinerate in a waste liquid incinerator, and incomplete combustion may occur due to a drop in temperature. By co-firing with
Rather than installing separate combustion furnaces for waste liquid and tubes, by unifying the furnace into a mixed combustion furnace, you can save on installation space, costs, labor, and
It has many advantages in terms of safety management, but the greatest effect is that it can reduce the concentration of "H" and "I" in the combustion exhaust. That is, the waste liquid containing 3H is 2Q
/hr, the displacement is 22m/hr, and the necessary air is supplied by the burner motor.

On the other hand, if 10 kg of tubes with 12 cm of adhesion are incinerated in 1 hour, the displacement will be 250.8 rri'/hr. Therefore, when waste liquid and tubes are co-combusted, the tolerance (safety) is calculated by comparing the concentration of ``SH, 1'' in the exhaust gas with the maximum allowable concentration in the exhaust gas, and the tolerance for 3H is 1X10 pci/cJX2X1O. c+fl=2μc
i2μCi÷(250,8rr['+22rn')=7
．． 3×10 μCi/c/, which is 0 for the maximum allowable exhaust gas concentration of “I(2×10−’μCi/cn?
．． The tolerance for cold I is 0.01μCi÷(250,F1m+22m)'=3.
7X10 uci/d, which is 0.1 for a maximum allowable exhaust gas concentration of 3X10 μCi/d of 12ゝl.
22, so the total tolerance is only 0.159. This means that it is possible to treat waste liquid with a concentration 10 times higher than that currently available when 3H waste liquid is incinerated in a dedicated furnace, which has a 3H tolerance of 0.455.

Since the present invention is as described above, it is extremely excellent as an incineration treatment apparatus for radioactive waste.

[Brief explanation of the drawing]

Fig. 1 is a side view showing an embodiment of the present invention, Fig. 2 is a partially cutaway side view showing an example of scintillation used in the present invention, and Fig. 3 is a partial view showing the preservation state of a tube to be incinerated. FIG.

Claims (1)

[Claims] An incinerator equipped with a cooling system to improve heat resistance and an air supply system to supply excess oxygen to the inside, and the combustion discharged from the incinerator when incinerating radioactive waste. Incineration of radioactive waste characterized by comprising a measuring device for measuring the concentration of radioisotopes in the combustion exhaust gas by guiding a part of the exhaust gas to a suitable adsorbent and detecting and measuring radiation in the adsorbent. Processing equipment.