RU211868U1 - TRANSPORT PACKAGING FOR THE TRANSPORTATION OF SPENT NUCLEAR FUEL - Google Patents

Abstract

The utility model relates to the field of nuclear engineering and is designed for multiple transportation of spent nuclear fuel (SNF) from nuclear power plants and long-term storage of spent fuel assemblies in a special storage facility. The device consists of a container and a case. The container includes a body with a bottom, main and additional covers, support rings placed on the lower and upper parts of the outer surface of the body, a casing welded to them, which together with the outer surface of the body and the support rings form a cavity filled with neutron shielding, located along the axis of the body and welded to the casing, at least twenty-seven heat-removing annular ribs. The body additionally contains a welded cover located between the main and additional covers. The main cover contains a recess made with the possibility of filling with a composition for protection against neutron radiation. The additional cover is provided with ribs made with the possibility of damping, and penetrations made with the possibility of creating gas pressure in the cavity between the main and additional covers and measuring the pressure. The cover is made in the form of a rack, including a base attached to the central tube, and three lattice steel plates, into which hexagonal tubes made of boron steel are inserted, forming cells for installing spent fuel assemblies in them. At least twenty-seven aluminum alloy heat sinks, plated with nickel and made in the form of plates with holes, are installed evenly and parallel to the lattice plates on the central tube, while the content of natural boron in the metal of the hexagonal tubes is not less than 1.3%. The utility model provides effective protection against neutron and gamma radiation, heat removal from the SNF loaded into the TUK. 12 ill.

Description

The proposed utility model relates to the field of nuclear engineering and is designed for multiple transportation of spent nuclear fuel (SNF) from NPPs and long-term intermediate (up to 50 years) storage of SFAs in a special storage facility with subsequent transportation to the SNF processing plant.

Known transport and packaging kit for transportation and storage of spent nuclear fuel according to patent No. 2127919 (G21F5/008, op. 20.03.1999). The device contains a case, a body with a cavity, a cover, fixing elements. On the case, made with a removable cover, a protective shell is installed, which is included in the bore on the inner surface of the case. The protective shell has a diameter greater than the diameter of the cover. At the same time, additional keys are installed on the body bore.

The disadvantage is that the case has a limitation on the residual heat of spent fuel assemblies (SFA) due to a small number of ribs for heat removal to the inner surface of the cask body and is intended mainly for the case storage of SFA in a special SNF storage, and, as a result, has small capacity for placing SFAs in a case.

The objective of the utility model is the possibility of transporting and storing SNF with a high enrichment in uranium-235 up to 5.0% and a large decay heat.

EFFECT: providing effective protection against neutron and gamma radiation, heat removal from SNF loaded into TUK.

The specified technical result is achieved by the fact that the transport packaging kit for the transportation of spent nuclear fuel consists of a container and a cover, the container includes a body with a bottom, main and additional covers, support rings placed on the lower and upper parts of the outer surface of the body, a casing welded to them, forming, together with the outer surface of the housing and the support rings, a cavity filled with neutron shielding, located along the axis of the housing and welded to the casing, at least twenty-seven heat-removing annular ribs, safety and sling pins in the upper part of the case, tilting pins and an eye in the lower part housings made with the possibility of moving the transport packaging set, a damper in the form of a perforated ring, and a shell made with the possibility of shock absorption, located in the lower part of the housing, the housing additionally contains a welded cover located between the main and additional covers, designed to protect against leakage of the radioactive medium from the cavity of the container, the main cover contains a recess made with the possibility of filling with a composition for protection against neutron radiation, the additional cover is equipped with ribs made with the possibility of shock absorption, and penetrations made with the possibility of creating gas pressure in the cavity between the main and additional covers and pressure measurement, while the slinging and safety pins, the eye are provided with cavities for filling with a composition for protection against neutron radiation and are removable, the heat-removing annular ribs are made with the ability to perform the functions of a damper, the case is made in the form of a rack, including a base attached to the central tube, and three lattice steel plates, namely the top plate and two middle ones, into which hexagonal pipes made of boron steel are inserted, forming cells for installing spent fuel assemblies in them, the base of the cover is made in the form of plates with holes with annular ribs placed between them, between the upper steel lattice plate of the rack and the base of the cover on the central tube, at least twenty-seven heat sinks made of aluminum alloy are installed uniformly and parallel to the lattice plates, plated with nickel and made in the form of plates with holes, while the content of natural boron in the metal of hexagonal pipes is not less than 1.3%.

Aluminum alloy heat sinks provide enhanced heat transfer. Nickel-plated heat sinks protect them from corrosion when exposed to water.

The use of heat-removing annular ribs on the surface of the container body as damping elements eliminates the need to use removable damping devices.

Placement of twenty-seven heat sinks on the casing makes it possible to carry out heat removal from hexagonal tubes to the inner surface of the container body and, thereby, reduce the temperature of SFAs placed in hexagonal tubes.

The utility model is illustrated by drawings, where:

1 - container,

2 - cover,

3 - container body,

4 - main cover,

5 - additional cover,

6 - neutron protection,

7 - ring ribs,

8 - casing,

9 - support rings,

10 - sling pins,

11 - safety pins,

12 - eye,

13 - hairpins,

14 - gasket,

15 - studs,

16 - gaskets,

17 - tilt pins,

18 - drain hole,

19 - damper,

20 - support shell,

21 - keys,

22 - deepening,

23 - nest,

24 - spring devices,

25 - penetration,

26 - additional penetration,

27 - damping ribs,

28 - penetrations,

29 - welded cover,

30 - base,

31 - central pipe,

32 - lattice plates,

33 - hexagonal pipes,

34 - planks,

35 - plate,

36 - ring ribs,

37 - radial ribs,

38 - heat sinks.

In FIG. 1 and 2 show a general view of the device;

in fig. 3 - top view of the device;

in fig. 4 - studs and gaskets;

in fig. 5 - penetrations;

in fig. 6 - additional penetration;

in fig. 7 - nest;

in fig. 8 - deepening;

in fig. 9 - spring devices;

in fig. 10 - welded cover;

in fig. 11 - general view of the cover;

in fig. 12 is a top view of the cover.

TUK consists of two main parts - container 1 and cover 2. The container includes a body 3, which is a thick-walled metal cylinder with a welded steel bottom, a main cover 4 and an additional cover 5, which are fixed to the flanges in the upper part of the body 3 using studs 13 and 15, with gaskets 14 and 16 installed in the connectors to ensure a tight seal. Support rings 9 are welded to the lower and upper outer parts of the body 3, to which the casing 8 is welded, forming together with the outer surface of the body 3 and the support rings 9 a cavity filled with neutron shield 6, which reduces the level of neutron radiation and, as a result, the level of radiation radiation by the outer surface of the housing 3. As a neutron shield 6 is used, for example, polysiloxane compound Silbor-5, which has good thermal conductivity and enhances heat transfer.

Twenty-seven steel heat-removing annular ribs 7 are located along the axis of the container 1, which are welded to the casing 8, acting as heat-removing elements, and together with the casing 8, support rings 9 and neutron protection 6 elements that reduce shock loads on the container 1 when falling. On the outer cylindrical surface of the body 3 of the container 1, with the help of threaded connections, devices for lifting and moving it are installed: two sling (cargo) pins 10 in the upper part of the body for lifting the TUK and moving it in a vertical position, two safety pins 11 in the upper part of the body 3 , two tilt pins 17 and an eye 12 in the lower part of the body 3 for moving the TUK in a horizontal position and moving from a vertical position to a horizontal one, and vice versa. Sling pins 10, safety pins 11 and eye 12 have cavities for filling with a composition for protection against neutron radiation, are removable elements and, if necessary, can be replaced. A plug can be installed in place of the removable lug 12.

The inner surface of the body 3 of the container 1, including the surface of the flange for installing the main cover 4, is covered with austenitic anti-corrosion welding. On the inner surface of the container 1 in the axial direction, there are two rows of dowels designed for installation and removal of the cover 2, oriented relative to the axis of the container 1. On the inner surface of the container 1, six stainless steel plates are welded, which serve as a support for the cover 2. Below, near the bottom, on The cylindrical surface of the housing 3 has a drain hole 18 for filling the container 1 with an inert gas (nitrogen or helium), which is closed with a plug during transportation and storage of the TUK. A damper 19 in the form of a perforated ring with a flange and a support shell 20 with a base in the form of a plate are welded to the bottom of the body 3. The damper 19 and the support shell 20 act as a shock absorber when the container 1 falls. There are dowels 21 in the lower part of the base, of which two dowels are 80 mm thick and one is 75 mm thick. Keys 21 are designed for orientation during installation and for fixing the TUK in the universal socket.

The main cover 4 is the first seal barrier. It is attached to the body 3 with the help of pins 15. In the upper part of the main cover 4, a recess 22 is made to fill it with a composition for neutron protection. In the center of this recess 22, a socket 23 is welded for the installation and removal of the main cover 4 using a rod with a bayonet catch.

Spring devices 24 are bolted to the lower surface of the main cover 4, which reduce the dynamic loads on the SFA during transportation and in emergency situations. The main cover 4 has a penetration 25 with a valve for drying the internal cavity of the container 1, for measuring the pressure inside the container 1 when filling it with gas, for gas sampling, and also for performing cooling operations before unloading the SFA into the wet storage. In the main cover 4 there is an additional penetration 26 for installing a resistance thermometer when measuring the gas temperature in the cavity of the container 1.

To ensure tightness in the connector main cover 4 - body 3 of the container 1, two rubber gaskets 16 are installed, which fit into the annular groove in the main cover 4 of the container 1 and are held in the groove with a ring with a cross section in the form of a dovetail. The ring is fixed in the groove with screws.

The additional cover 5 is the second barrier of tightness of the inner cavity of the container 1 and is attached to the upper flange of the body 3 of the container 1 with the help of pins 13. To ensure tightness in the connector, the additional cover 5 - the body 3 of the container 1 has one rubber gasket 14. The gasket 14 fits into the annular groove in the additional lid 5 of the container 1 and is held in the groove by a dovetail ring. The ring is fixed in the groove with screws. On the outer surface of the additional cover 5, damping ribs 27 are welded, designed for shock absorption under shock loads. Also, the additional cover 5 is provided with penetrations 28 to create gas pressure in the cavity between the covers and measure the pressure. To capture the additional cover 5 during its installation / removal, holes are provided in the damping ribs 27. Instead of a plug, a connecting device is attached to the valve sleeve on the additional cover 5 for connecting communications when entering into the cavity between the main 4 and additional 5 covers of the gas medium, for connecting communications when taking a sample for analysis of the medium from the cavity, to create and release pressure between the main 4 and additional 5 covers, as well as when testing the gasket 14 on the additional cover 5 for tightness.

On the inner surface of the body 3 of the container 1, between the main cover 4 and the additional cover 5, it is possible to install a welded cover 29 in case of unrecoverable leaks from the cavity of the container 1 through the main cover 4 (pressure drops). The welded cover is a protection against leakage of the radioactive medium from the cavity of the container 1 when it is installed in the storage.

Case 2 is a metal structure in the form of a rack, including a base 30 welded to a central pipe 31, and three steel lattice plates 32 welded to it (the top plate and two middle ones), into which hexagonal pipes 33 made of boron steel are inserted, forming cells for installation they contain spent fuel assemblies, while the content of natural boron in the metal of hexagonal pipes is not less than 1.3%. This is due to the need to ensure the nuclear safety of the TUK, which is carried out at a neutron multiplication factor Kef<0.95. In the upper and lower parts of the hexagonal pipes 33 have strips 34 fixed on the edges. The slats are welded to the slats of adjacent hexagonal tubes 33, to the lattice top plate 32 and to the plate 35 of the base 30 of the cover 2. The base of the cover 2 is welded to the central tube 31 in the lower part and serves as a shock absorber under dynamic loads. The base 30 of the cover 2 is made in the form of two plates 35 with holes. Ring 36 and radial 37 ribs are welded between the plates. Between the steel lattice upper plate 32 and the base of the cover 2 on the central tube 31, twenty-seven heat sinks 38 made of aluminum alloy, plated with Nickel, which are plates with holes, are evenly and parallel to them. Between themselves, the heat sinks 38 are spaced by means of bushings on the central tube 31, as well as by engagement in the grooves of the guide boxes. The upper end of the central tube 31 of the cover 2 is made in the form of a socket for a bayonet grip for lowering the cover 2 into the container 1 and extracting it from the container 1 using a reloading device rod.

The use of transport and packaging kit in the industry is as follows.

The TUK for loading spent nuclear fuel (SFA) into it is installed in the universal socket of the spent fuel pool of the NPP reactor compartment. The installation of SFA is carried out under a layer of water in a case 2 located inside the container 1 by a refueling machine.

After loading into container 1 of the SFA, the main cover 4 is installed. The traverse is coupled with slinging 10 and safety pins 11, the container 1 is removed from the universal nest and installed on the intermediate platform, water is completely drained from the body 3 of the container 1 through the valve in the lower part of the body 3. After that, the TUK is installed on the service site.

All surfaces of the container 1 are dried according to the instructions in force at the nuclear power plant. To dry the internal cavity, open valves are used on the main 4 and additional 5 covers.

After drying, the TUK seals the main 4 and additional 5 covers. To do this, the screws are simultaneously turned counterclockwise until depressurization, while the distance from the stop of the screws to the surface of the main cover 4 should be 7-10 mm. After that, the tightening of the nuts on the studs is completed.

The tightness of the detachable connections of the inner cavity of container 1 is checked. The inner cavity of container 1 is filled with nitrogen by performing the following steps in sequence:

instead of a plug, a fitting with a pressure gauge is connected to the valve of the main cover 4, and a connecting device is installed on the valve in the lower part of the body 3 of the container 1 instead of a plug.

connect the device connecting to the nitrogen supply system and fill the internal cavity of the container 1 with nitrogen, creating a pressure of 0.1 ... 0.3 MPa (indicated in the operating manual). The pressure is measured using a pressure gauge on the fitting;

close the valves on the main cover 4 and the valve in the lower part of the body 3 of the container 1 by turning the key clockwise until it stops. Turn off the nitrogen supply. Remove the fitting from the main cover 4 and the connecting device from the body 3 of the container 1;

install the previously dismantled valve plugs of the main cover 4 and the plug;

check the tightness of the inner cavity of the container 1. To do this, install fittings instead of plugs (with pressure gauges):

a) in the main cover 4;

b) in the cork of the body 3 of the container1;

c) on the main cover 4 at the exit from the interlayer space (alternately at each of the two exits).

An additional cover 5 is installed. The space between the main 4 and additional 5 covers is filled with nitrogen by performing the following steps in sequence:

instead of a plug, a connecting device is installed in the valve sleeve;

connect the device connecting to the nitrogen supply system and fill the space between the lids with nitrogen, creating a pressure of 0.1 MPa more than the pressure in the internal cavity of the container 1. The pressure is measured using an additional pressure gauge installed in the sleeve of the supply system (with nitrogen);

close the valve by turning the key clockwise until it stops. Turn off the nitrogen supply. Remove the connecting device from the additional cover 5.

install the previously dismantled valve plug and additional cover 5 in place;

check the tightness of the cavity between the main 4 and additional 5 covers. For this, a fitting (with a pressure gauge) is installed in the main cover 4 instead of a plug. Leakage of nitrogen is determined by the readings of pressure gauges after holding for at least 10 minutes. No pressure drop allowed.

remove the fitting and install a plug in its place.

After TUK is loaded and decontaminated at the NPP, it is necessary to verify the steady-state parameters of the radiation level and surface radioactive contamination of the TUK, the temperature and pressure of the medium in the internal cavity of the TUK and in the space between the main and additional covers.

Claims (1)

Transport packaging set for the transportation of spent nuclear fuel, consisting of a container and a cover, the container includes a body with a bottom, main and additional covers, support rings placed on the lower and upper parts of the outer surface of the body, a casing welded to them, forming together with the outer surface of the body and supporting rings a cavity filled with neutron shielding, located along the axis of the body and welded to the casing, at least twenty-seven heat-removing annular ribs, safety and sling pins in the upper part of the body, tilting pins and an eye in the lower part of the body, made with the possibility of movement of a transport packaging set, a damper in the form of a perforated ring and a shell made with the possibility of shock absorption are located in the lower part of the body, the body additionally contains a welded cover located between the main and additional covers, made with the possibility of protecting against leakage of radioactive of the container cavity, the main lid contains a recess that can be filled with a composition for protection against neutron radiation, the additional lid is equipped with ribs made with the possibility of shock absorption, and penetrations made with the possibility of creating gas pressure in the cavity between the main and additional covers and measuring pressure, while the slinging and safety pins, the eye are provided with cavities for filling with a composition for protection against neutron radiation and are removable, the heat-removing annular ribs are made with the ability to perform the functions of a damper, the cover is made in the form of a rack, including a base attached to the central tube, and three lattice steel plates, namely the upper plate and two middle ones, into which hexagonal pipes made of boron steel are inserted, forming cells for installing spent fuel assemblies in them, the base of the cover is made in the form of plates with holes with annular ribs placed between them frames, between the upper steel lattice plate of the rack and the base of the cover on the central tube, at least twenty-seven aluminum alloy heat sinks, plated with nickel and made in the form of plates with holes, are installed evenly and parallel to the lattice plates, while the content of natural boron in the metal of hexagonal pipes not less than 1.3%.

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