Protective container for transportation of spent nuclear fuel

 

(57) Abstract:

Protective container includes a housing that is inserted into the cavity of the removable housing part, in which holes in the top Board and the diaphragms placed pipe covers. The protective container is closed from above by a sealing cap. Removable part is equipped with attached tube channel, intended for removal of radioactive water from the bottom of the container by way of vacuum suction. The axis of the channel is offset from the axis of the container at a distance of 0.75-0.95 radius of the inner cavity of the container, and the lower end of the tubular channel is located above the bottom of the container with a clearance of not more than the inner radius of the pipe channel. The lower flange of the container is equipped with an additional removable flange having a slope in the direction of the tube channel on the angle 1-4ofor the round-up of radioactive water into the corner of the bottom of the container when it is removed by way of vacuum suction through the pipe channel with the cover off. The technical result of the present invention is expressed in nuclear safety. 4 Il., table 1.

The invention relates to a mobile protective containers for safe transportation of spent nuclear fuel from storage after jadernoi reaction.

One of such conditions is the lack of water in the container or its presence below the permissible according to the calculations of nuclear security number. To do this, after boot covers with spent fuel in the container and before transporting water from the bottom of the container should be removed to values below the allowable amount. For example, for protective container TK-18 the presence of water after boot covers SNF before transportation should not exceed 2.5 litres.

Known protective container, taken as a prototype (see "Containers for transportation of spent fuel elements of nuclear power plants", Proceedings of CKTI, 142 issue, Leningrad, 1977, page 13, Fig. 2), comprising a housing that is inserted into the cavity of the container is removable part, in the holes of the top Board and transverse diaphragms where pipe covers SNF, and closed at the top by a sealing cover.

Also known containers (see ed. St. N 1301205, Fig. 3, Fig. 4 and Fig. 5), in which the removal of water from their cavity to drain the bottom by gravity through the openings in the walls of the containers and through the shutoff valves located below the bottom of the container.

The disadvantages of these protective containers are available if asiausa sealing system the discharge of radioactive water from the bottom of the container in a team capacity without leaking it on the floor of the room. This full tightness of the drain system is not achieved and the current leakage of radioactive water polluted areas, which will remove the water from the containers.

Known pumping plant for the removal of liquids by their vacuum suction from the bottom of the tank through the top of their neck. (see "Sanitary-technical equipment of buildings", C. S. Kedrov, E. N. Fisher, M.: stroiizdat, 1989, page 302, Fig. 20.1 (b). The specified pump installation does not require holes in the walls of the container. The pump unit consists of a tank (inlet tank, pump and suction pipe. When possible leakage of fluid in the joint of the vacuum system to the pump at the top of the neck tank (inlet tank) are not on the floor of the room, and down again to the bottom of the tank (inlet tank), which eliminates possible contamination of the premises by the liquid.

The objective of the invention is to simplify the design of the container for removing radioactive water from the bottom of the container without holes and valves in the walls and no water leaks on floor space, as well as the reduction of the balance of the water at the bottom of the container due to the tilt of its axis for eviction of water in the corner with the deletion.

This dosha offset from the axis of the container at a distance of 0.75-0.95 radius of the inner cavity of the container, the upper end of the tubular channel is inserted in the top Board removable parts in sostykovochka socket attach the vacuum system for collecting water from the bottom of the container through the tubular channel and the bottom channel is located above the bottom of the container with a gap equal to not more than the inner radius of the pipe channel, while the lower flange of the container is equipped with an additional removable flange having a slope in the direction of the pipe channel at an angle of 1 to 4o.

Eccentric attachment tube channel for the removable parts with its location in the cross section of the cavity of the container eliminates the possibility of water leaks on the floor of the premises and provides the suction of water from the corner of the container, and allows the body of the container without holes and isolation valves in the walls, which simplifies the design of the container. The connecting socket in the top Board removable parts, in which is inserted the upper end of the tubular channel provides the ability to attach to a vacuum system for collecting water from the bottom of the container through the tubular channel.

The gap end of the tube channel on the bottom of the container size is not more than the inner radius of the channel allows the use of the phenomenon of wetting by water butt canal and capillary affma, after its suction reduces the depth of the residual water in the zone of the tube channel below the gap.

Equipping the lower flange of the container attached to it additional removable flange with a gradient of 1-4oprovides the optimal inclination of the container in the direction of the pipe channel and the sleeves of water in the corner area of the bottom of the container before it is vacuum suction that reduces the amount of residual water in the container after its suction.

The invention is illustrated by drawings, where Fig. 1 shows the proposed protective container, a vertical section; Fig. 2 shows a node I Fig. 1 - position of the pipe channel in the removable parts and the cavity of the container, as well as placement driven into a corner area of the water container by tilting the container in the direction of the pipe channel, vertical section; Fig. 3 shows a cross section a-a in Fig. 2 - positioning the tubular channel and the water at the bottom of the container; Fig. 4 is a wiring diagram for the connection of the vacuum system in the expansion slot of the tube channel when the cover of the container, a vertical incision.

Protective container includes a housing 1, a cover 2, the removable part 3, pipe covers 8 installed in the removable part 3 their bottom ends to the bottom of the housing 1; and t is the removable parts 3 installed replaceable sleeve 6 to provide the same clearance under the cover 2 for all of the covers 7 and 8. Removable part 3 is supplied attached to the top Board and the spacer apertures 12 pipe channel 5 for collecting the water from the bottom of the housing 1.

The axis of the pipe channel 5 offset eccentric (Fig. 3 and Fig. 2) relative to the axis of the container at a distance (0,75 - 0,95) the radius of the inner cavity of the container. The bottom end of the pipe channel 5 is located above the bottom of the container with a gap equal to not more than the inner radius of the pipe channel 5, and above the upper end of the tubular channel 5, inserted in the top Board removable parts 3, there is a connecting socket 4 (see Fig. 1) for connecting the sealing device 14 (Fig. 4) above the cavity of the housing 1 through a flexible hose 15 to a vacuum system for collecting water from the bottom of the container when the cover 2. For tilting the axis of the protective container and eviction of water in the corner area of the bottom of the lower flange 9 of the container is fitted (Fig. 1) attached to it by means of bolts 10 and nuts 11 additional removable flange 13 having a slope of 1 to 4oin the direction of the pipe channel 5.

The optimum angle of inclination of the container 1 to 4oin the direction of the pipe channel, providing a minimum residual volume of water in the bottom of the container when the eccentric offset of the axis of the channel, confirmed the following BR> C is the eccentricity of the tubular channel, in the present invention it is set to C = (0,75 - 0,95) R;

d is the distance to the axis of the channel from the inner cylindrical cavity of the container d = R - C = (0,05 - 0,25) R;

r is the inner radius of the tubular channel;

W - the gap between the bottom of the container and the bottom end of the pipe channel in the present invention taken W < r;

- the angle of the container in the direction of the pipe channel;

h - the height of the water "hoof" when the tilt angle ;

x - base height of the water "hoof" when the tilt angle ;

m - length water "hoof" to pipe channel when the tilt angle ; m = x - d;

a - half the length of the straight side of the water "hoof" when the tilt angle .

Calculation of residual water at the bottom is inclined in the direction of the channel of the container (Fig. 2 and Fig. 3) is produced by the known formula for the volume of water "hooves" (see I. N. Bronstein, K. A. semendjajew - "Handbook of mathematics", Moscow, "Nauka", 1986, page 188, Fig. 2.51)

< / BR>
where

where

< / BR>
< / BR>
where

From (2) and (3) follows:

< / BR>
Volume according to the formula (4) when changing x has a minimum, which can be found by calculating the value of which requires complex calculations.

In a first approximation, the value of x when totoromobile minimum square secene, which will match VminOSTwhere, substituting (3), we get

< / BR>
where xSmin= 2d, ... (6) and Smin = 2W d (7).

We get the following, substituting (6) into (4):

< / BR>
thus where

As an example, we determine the values of VminOSTand*in the container TK-18, with values of R = 38,8 cm; d = 4.8 cm; W = 0.1 cm, 0.2 cm; 0.3 cm; 0.4 cm; 0.5 cm;

< / BR>
< / BR>
The results of calculations are presented in table I.

When the vertical position of the container, i.e. when = 0oand W = 0.3 cm volume of water at the bottom of the container is 1418,1 cm3. When tilting the container by 3.58oand W = 0.3 cm, the amount of water the container is reduced in time.

An example with W = 0.3 cm is given from the practice of sucking water from the bottom of the container TK-18. When the suction wetting water end of the channel and the capillary effect in the channel r = 0.5-0.6 cm when W < r using vacuum pressure not exceeding 30000 PA (225 mm RT.CT.) allows you to remove the water from the container TK-18 to a residual depth in the area of the pipe channel W 0,3 see the Depth of the residual water was controlled drop to the bottom through the pipe channel pin on the size of the wetted by water footprint at the end of the pin, the lower end of which is pre-covered with chalk or kaolin.

In the remainder of the water at the bottom of the container, taken 1 to 4o. Large draft angles are unacceptable because of the possibility of jamming of the diaphragm covers when installing them under the pressure of its own weight in aperture removable parts of the container.

To remove the water from the bottom of the protective container (Fig. 1) it is installed on the horizontal floor of the room, on the bottom attached additional flange 13 having a draft angle of 1 to 4othat provides tilting of the container and the sleeves of the water at its bottom in the area of the pipe channel 5. Protective container can also be installed in the shop decompression the pit, room for boats, etc.

The removal of water is produced when the cover 2 after loading into the cavity of the container covers 7 and 8. For this purpose the connecting socket 4 installing the sealing device 14 (Fig. 4) and the pressure wheel is compressed on its end in the connecting socket 4 sealing rubber strip, and the upper hose 15 is connected to the vacuum system.

After that include vacuum and produce a suction of water from the bottom of the container through the channel 5, the connecting device 14, the hose 15 into the drain tank vacuum system.

It is possible water leak in the sealing connecting socket 4 through the gaps in removable the e removal of water from the container. About the end of the suction from the bottom of the container indicates a leak in the gap end of the pipe channel 5 over the bottom of the housing 1, the increase of the vacuum pressure and the characteristic audible noise. Then turn off the vacuum system, disconnect the hose 15 and remove the sealing device 14. The depth of the residual water in the zone of the pipe channel 5 control drop to the bottom through the channel 5 pin on the size of the wetted by water footprint at the end of the pin, pre-coated with chalk. After that, the body 1 of the container, install the cover 2.

The proposed protective container and ensures reliable operation in accordance with the nuclear safety requirements by simplifying construction, reducing the remaining water in the container to lower the amount of permissible and excludes the contaminated water of the building during its removal from the container.

Protective container for transportation of spent nuclear fuel, comprising a housing inserted into the body cavity of the removable part, in the holes of the top Board and diaphragms where pipe covers SNF, and closed at the top by a sealing cap, wherein the removable portion is supplied attached to nutrena cavity of the container, the upper end of the tubular channel is inserted in the top Board of the removable parts in the connecting socket attach the vacuum system for collecting water from the bottom of the container through the tubular channel, and the lower end of the tubular channel is located above the bottom of the container with a clearance of not more than the inner radius of the pipe channel, while the lower flange of the container is equipped with an additional removable flange having a slope in the direction of the pipe channel at an angle of 1 to 4o.

 

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