JPS6082999A - Radioactive gas waste treater - 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 [Technical Field of the Invention] The present invention relates to a radioactive gaseous waste treatment device for a nuclear power plant.

[Technical Background of the Invention] A radioactive gas waste treatment system for a Zhouteng water nuclear power plant generally includes an air extractor 1, a preheater 2, and a main condenser connected to each other, as shown in FIG. recombiner 3, condenser 4,
A dehumidifier 5, a dehumidifier 6, prefilters 7a and 7b, a main adsorption delay device 8, a filter 9, a vacuum pump 10, and a stack 11 are connected in series with piping. During reactor operation, one air extractor was extracted from the main condenser.
11 gases include H2.02 generated in the nuclear reactor and short-lived highly radioactive activated gases (oxygen, nitrogen iso-1-1, etc.)
and long-lived activated gas (clear 1-hen, 4-senone, etc.), and is diluted with multi-ω water vapor for driving the air extractor 1. This exhaust gas is first heated in a preheater 2, hydrogen is removed by an oxyhydrogen recombination reaction in a recombiner 3, and most of the water vapor is condensed in a condenser 4 to reduce its volume. Most of the 71f waste that has flowed out of the condenser 4 is air, and it contains activated gas and a small amount of water vapor, or it is used in the dehumidifier 5 and The dehumidifier 6 dehumidifies and dries the material to a dew point of about -30°C.

The delay device consists of prefilters 7a, 7b disposed at the most upstream side and a main adsorption delay device 8 downstream thereof, and the main adsorption delay device 8 includes a plurality of activated carbon columns 8a, 8b filled with activated carbon as an adsorbent. , 8c is connected in series with pipe 1 (M is formed), where it adsorbs and delays the life nucleus 1Φ (mainly krypton and xenon) and attenuates the radioactivity to below the permissible value. The life nuclide has been attenuated for about 4τ up to this point, but if it is supplied to the main adsorption delay device 8 with insufficient attenuation, the activated carbon that is the adsorbent will be consumed due to negative effects such as decay heat and secondary radiation effects. , there is a problem that the service life is reduced.

Therefore, prefilters 7a and 7b are provided at the most upstream side of the delay device.
is provided to prevent short-lived nuclides from entering the main @delay device 8. Further, the pre-filters 7a and 7b filter solid decay products and moisture, and protect the activated carbon in the main target@delay device 8.

In particular, moisture or moisture not only reduces the function of live coal but also increases fluid pressure loss, eventually leading to system operation being stopped, so sufficient dehumidification is usually not carried out on the upstream side of the condensation. If the dehumidifier 5, ++52 humidifier 6 malfunctions, or there is a possibility that moisture may flow into the delay device N due to incorrect operation during startup/stop or periodic inspection, the prefilters 7a, 7b may This prevents the water from flowing into the main adsorption delay device 8.

In this way, the prefilter 7a, 7b has the main purpose of protecting the main adsorption delay device 8, so the delay time can be short. Therefore, the activated carbon serving as the adsorption agent is small h1 and J, and the activated carbon tower 8a, 8b is Compared to the activated carbon in C3 (), the activated carbon filled inside is likely to deteriorate and the frequency of replacement increases, so the structure is generally such that the filling can be replaced. As shown in Fig. 1, two lines are installed, and isolation valves 12a, 12b, 13a, and 13b are installed at the front and rear to make the AC operation "f l h".

The exhaust gas exiting the main adsorption delay device 8 is blocked by a filter 9, and then sent to a stack 11 by a shell pump 10 and discharged to the public.

In Fig. 1, reference numeral 14 is a pipe for recirculating non-residues to the stack 11 or to the main condenser during start-up/stop or scram; This is a valve for switching the flow path.

As shown in FIG. 2, the structure of the prefilter 7a, 7b is a cylindrical upper body 17 and a conical lower part 1i!
If 18, 19 cars are connected to the upper end of the upper shell 17, and a filling outlet 20 is connected to the lower end of the lower shell 18. The flat plate 19 is provided with a filler filling port 21, a waste inlet 22, and a gas outlet 23.
is connected to a gas tube 24 that introduces gas into the container, and the gas tube 24 opens into the filled JaI layer inside the container with a filter 25 at its end.

The filler is filled by pushing through the lid 26 of the filler filling port 21, and due to the presence of the series 25, a space 27 is formed by the angle of the filler at the waste inflow portion.

In addition, the lower part of the packed bed is installed at the lower part of the outlet pipe 20 for the packed material 11 (
It is supported by a tilted support plate 28. The filling material removal pipe 20 passes through the floor 29 to the lower floor.

To take out the filling, use the take-out pipe 30 and the support plate 28.
By pulling out the blind plate 31 connected to the support plate 28
This is done by sliding the C and letting the filling fall downward, but there is no need to take out all the C unless it is a filling or a cavity.
trll If you take out the vicinity of space 27 where the adult bull adult is most abundant and exchange C1, it will be Jζ.

As for the packing, activated carbon columns 8a, 8b, 8c are used as described above.
``Non 1'', which is made by crushing Genbukichi, is also used, which uses the same activated carbon that is filled in the charcoal.

In this case, there is no adsorption effect, and the prefilter 7a, 7b
Although it should be considered a delay device protection filter rather than part of the delay device, it is less susceptible to deterioration from heat and DI radiation than activated carbon, and the life of the fill is longer. but,
Because the pressure loss increases when moisture enters the packed bed, the pressure loss increases.

"Problems with backlighting technology" 7j In the conventional prefilter, 1 - ■
There were problems like enemies.

The four J-type gases are indicated by arrows in Figure 2.I, 1υwomanl
, from Kasu population 22 to fathom population 24, 2+1j27
-C spreads into the packed bed, moves the packed bed upwards and flows out of the container from gas exit 1: + 2 a, or regular inspection 6 ('
to r. j, When A is stopped and the system is kept under negative pressure, if you accidentally hear the valve that leads to the popularity of the Itto flow, the reverse thrust will be X years and the angle of repose that forms the space 27. is the inverse i of gas
C collapses due to fj, and the filling material is sucked into the heart inlet tube 24. This causes the filling material to flow back and scatter, resulting in discharge (,+r
, σ) Blockage occurs and system KjC cannot operate.

In addition, even if this erroneous operation does not occur, during a scram of the Oji reactor, the system flow rate will increase, so the exhaust gas will be recirculated from the pipe 14 to the main condenser by listening to valve 5 in Figure 1. Otherwise, due to the high purity of the main condenser, the waste on the downstream side after the dehumidifier 5 is drawn into the main condenser 1, resulting in a backflow and the filling in the pre-noil toughs a and /b. A phenomenon of backflow scattering of objects occurs.

Backflow scattering of the filler is more noticeable in the case of activated carbon with a small ratio Φ than in the case of sand.

In addition, as shown in Fig. 2, the 1-prefilter is
Although the filling is to be taken out downstairs, a container for receiving the filling is placed above the take-out container 20.
Because of this, there is a risk that the powder of the filling (Iυ) will be scattered around +LjID, and the radiation waves of the worker may be exposed to radiation waves. The disadvantage was that the C flowed down and was difficult to work on.

[Object of the Invention] The present invention improves the drawbacks of the pre-filter used in the conventional gaseous waste treatment equipment as described above, prevents the backflow of the filling material, and prevents the filling material from scattering. The object of the present invention is to provide a radioactive gas open matter processing apparatus having a pre-filter that can easily and safely carry out the intersection of 1φ.

[Summary of the invention j The present invention is that the pre-suction container disposed at the most upstream side of the delay device J has a double layer (1'4 structure) consisting of an airtight outer shell and a removable inner shell filled with an adsorbent. and internal dimensions (J,
It is large enough to be stored in a drum can for solid waste storage. For this reason, the adsorbent can be taken out with the inner shell and placed in a C drum, and the filling can be carried out by installing the inner shell together with the external pressure. By increasing the size of 1/615 υi and installing a net, backflow scattering of the adsorbent can be prevented. In addition, before exchanging the adsorbent, the inside of the adsorber is heated with -L]'b■'-, and the air tinged with moisture is returned to the flow side by the enono blow to the main adsorption delay device. The piping arrangement must be configured to prevent moisture intrusion due to niobium.

[Embodiment 1 of the Invention] Hereinafter, the configuration of a radioactive gas waste fruit processing apparatus according to the present invention will be described with reference to FIGS. 3 to 4.

In FIG. 3, pre-adsorbers 32a and 32b are installed in parallel upstream of the main adsorption delay device 8. 12a, 12b and preadsorption device 32a, 32fz
7) Piping 1 between (tJ + L) f L33 a,:
IE air inflow ff134a, 34b with 33b
bx L, also pre-adsorbers 32a, 33b and isolation valve 1
3'1. Return from the piping between I and 13b [Ii:i
35a, 3bb are branched and return piping 35d, 35
b <yo, middle 1iil iJ stop valve 36a, 3611
is provided and connected to the piping between valve 1 (5) and WS5. The upstream sides of the air inlet chambers 34.I and 34b are connected to an air supply device 4. vessel 32a
, before and after 32b] Differential pressure ii for measuring and monitoring A
j ” There is L.

The configuration other than the above is the same as in FIG.

The structure of the preadsorption device is shown in Figure 1i-2-4-31,
2, the gas inlet 38 and the gas outlet 39 are cut out (the upper part of the cylindrical outer body 40 has a flange 41), and 1
- A chain handle 43 for connecting the drain pipe 42 is installed in the section.

An annular support base 45 is provided at the lower part of the outer shell 40 for arranging and supporting the cylindrical inner shell 44 . Inner 11
4III has an annular flange portion 46 on the upper surface and the upper surface.
47, and the inner diameter part of the lower flange part 47 has a mesh 48.
is stretched to support the packed bed of activated carbon filled in the inner shell 44. Further, a gasket 49 is provided on the lower surface of the flange portion 47, and the weight of the inner shell 44 causes the flange portion to
Gas leakage between the support base 45 and the support base 45 is prevented. Furthermore, a hanger 50 is attached to the flange portion 46 on the upper side of the inner body 44 and is detachably attached with a screw.

A support plate 51 is provided on the upper part of the inner surface of the outer shell 40, and the inner shell/
A presser plate 52 for pressing and fixing 14 from above can be attached by tightening bolts.

The presser plate 52 is shaped like a single character, a triple or a cross, and depending on the shape, two, three or four support plates 51 are provided on the same circumference on the inner surface of the outer shell 40.

At the top of the container, a container 53 is attached to the flange 41 with bolts to keep the inside of the container airtight.

The outer dimensions of the inner shell 44 are such that it can be accommodated in a drum can with a capacity of 200° C. which is used to store radioactive solid waste within a nuclear power plant.

The inner body 44 can be taken out by removing the lid 53 and the presser plate 52, and can also be loaded into a container. At this time, a support stand 45 is used to attach the inner shell 44 to a predetermined position.
is provided with a recess in the center that matches the outer circumference of the inner shell 14 (which serves as a guide).
It serves as a guide for suspending objects vertically.

Next, the operation of the above embodiment will be explained.

The exhaust gas is extracted by the air extractor 1 to the radioactive gas waste processing equipment, and passed through the preheater 2, recombiner 3, condenser 4, dehumidifier 5, and dehumidifier 6 to remove hydrogen, dehumidify, and dry. It flows into the stationary adsorption device 32a.

At this time, the preadsorption device 32b is in a standby state with the isolation valves 12b and 13b closed. In addition, stop valves 33a and 33b
, 36a and 36b are closed.

In Fig. 4, the exhaust gas flowing into the pre-adsorption device from the gas inlet 38 is! The waste flows into the activated carbon packed bed through a gap of $548, where it delays the adsorption of short-lived nuclides and filters impurities such as solid decay products, and then flows to the waste outlet 39.
After the long-lived nuclide adsorption is delayed by the main adsorption delay device 8 and the radioactivity is sufficiently attenuated, it is released from the stack 11 into the atmosphere via the filter 9 and the vacuum pump 10.

On the other hand, if backflow occurs in the system as mentioned above,
Since the inner shell 44 of the pre-adsorber is provided with a net 48 to support the activated carbon, the activated carbon does not scatter in a reverse flow.

By the way, it has been experimentally determined that the minimum flow velocity at which activated carbon backflow scatters is about 1 m/s, and since the backflow flow m of dregs is approximately 0.1+n3/S, the flow velocity inside the inner shell 44 is It is about 0.4 m/s, which is smaller than the activated carbon backflow scattering flow velocity. Therefore, in Figure 4, J5 is the gas inlet 38.
There is no problem even if the flow direction of the waste outlet 39 is reversed, but if the drain discharge when moisture enters is taken into consideration, the fourth
The flow direction is preferably as indicated by the arrow in the figure.

Now, if moisture flows into the pre-adsorption device 32a for some reason and the activated carbon gets wet (this is detected when the contact pressure measured by the differential pressure 37 rises).

If the pre-adsorber b or the activated carbon itself deteriorates and becomes unusable, close the isolation valves 12a and 13a, and close the isolation valves 12b and 13.
Listen to b-C Switch to pre-adsorber 32b. Thereafter, the activated carbon in the pre-adsorber 32a is replaced, but prior to that, the C stop valves 33a and 36a are opened and the air C air 10- is pumped through the pre-adsorber 32a to remove the radioactivity in the pre-adsorber 32a. This is effective in reducing damping and increasing work safety. Since air tinged with radioactivity and moisture due to air blowing is returned immediately before the dehumidifier 5 on the upstream side, there is no risk of sending moisture to the main adsorption delay device 8 on the downstream side. 6. If the above blow-out is to be carried out when the plant is stopped for regular inspections, etc., the valve 16 may be closed and the dehumidifier 5, 1152 and humidifier 6 may be operated.

To replace the activated carbon in the pre-adsorber, remove the container 53 and the holding plate 52, lift the activated carbon together with the inner shell 44 using the lifting device 50, store it in a drum for radioactive solid waste storage, and then remove the activated carbon from the hanging shell. 50 is also removed and the inner body 4
4, put the lid on the drum, and transport it to Yuzoan Theory. Thereafter, the inner shell 44 filled with new activated carbon is installed.

Since most of this replacement work can be done remotely, there is almost no radiation exposure during the work, significantly improving work safety and significantly reducing work time.

The pre-adsorber delays the adsorption of bionuclides which are considerably attenuated upstream, and filters out solid decay products and moisture. In general, it is sufficient to fill the inner shell with the dimensions stated in the claims, but if the capacity of the plant is large and this is insufficient, two or more pre-adsorbers may be connected in series. In this case, the activated carbon may be exchanged for a specific preadsorption device as needed.

Further, the return pipes 35a and 35b are not limited to the positions shown in FIG. 3, but may be connected to a pipe between the dehumidifier 5 and the dehumidifier 6, for example.

[Effects of the Invention] According to the radioactive gas waste treatment apparatus according to the present invention, it is possible to prevent backflow scattering of activated carbon in the preadsorption device, and the activated carbon in the preadsorption device can be easily and safely replaced in a short time. Therefore, the reliability of the protection effect on the main adsorption delay device can be improved.

[Brief explanation of drawings]

Fig. 1 is a schematic system diagram showing a conventional radioactive gas waste treatment device, Fig. 2 is a vertical cross-sectional view showing the structure of a conventional prefilter, and Fig. 3 is an illustration of a radioactive gas waste treatment device according to the present invention. FIG. 4 is a longitudinal sectional view showing a pre-adsorption device according to the present invention. 1. Air extractor 2.・・・
・・・・・・Preheater 3・・・・・・・・・・・・Recombiner 4・・・・・・・・・・・・Condenser 5・・・・・・・・・...Dehumidifier 6...Dehumidifier 7a, 7b...Prefilter 8...Main adsorption delay device 8a, 8
1) ,80-Activated carbon tower 9...Filter 10...Vacuum pump 11...
......Stacks 12a, 12b, 13a, 1
3b......Isolation valve 14...Piping 15.16...Valve 17... Upper shell 18...Lower shell 19...Flat plate 20...Filling material removal pipe 21・・・
・・・・・・・・・Filling material filling port 22・・・・・・・
...... Gas inlet 23 ...... Dregs outlet 24 ...... Introductory pipe 25 ...... Series 26......Lid 27...Space 28...Support plate 29... ...... Floor 30 ...... Takeout tube 31 ...
... Old roots 32a, 32b... Pre-adsorption device 33a, 33b... Stop valve 34a, 34b... Waste inflow pipe 35a, 35b... Return pipe 36a, 36b...・Stop valve 37...Differential pressure control 38...Gas inlet 39...
・・・・・・Gas outlet 40・・・・・・・・・・・・
Outer body 41...Flange 42...
・・・・・・Drain pipe 43・・・・・・・・・・・・
End plate 44...Inner body 45...Support stand 46...Flange section 17...・
......Flange part 48...
... Net 49 ... Gas Quot 50 ...
...... Hanging tool b1 ...... Support plate 52 ...... Pressing plate 53 ...... ...Patent attorney Sa Suyama - Figure 1 011 Figure 2 Figure 3 4 9 1 Li II

Claims (3)

[Claims] (1) In a radioactive gaseous waste treatment equipment having a delay device consisting of a plurality of containers filled with adsorbent to treat radioactive exhaust gas from a nuclear power plant, 101 before being placed at the most upstream position of the delay device. Radioactive gas disposal characterized by being formed into a double-sided structure with an external adsorption container (an external container that maintains airtightness with the outside) and an inner container that is removably placed inside this outer container and filled with an adsorbent. Material processing equipment. (2) The radioactivity according to claim 1, characterized in that the outer dimensions of the inner shell filled with the adsorbent are of a size that can be stored in a drum for storing radioactive solid waste at a nuclear power plant. Gaseous waste treatment equipment. (3)′! Two or more containers at the most upstream side of the extension device are arranged in parallel, with isolation valves installed before and after each container, and an air inflow pipe connected to the piping between the upstream isolation valve and the container. A feature characterized in that the return piping to the upstream side is branched from the piping between the downstream side isolation valve [radioactive gas ff according to claim 1]! ! Tomono processing! ! i11? ? .