DE2157287A1 - Method and apparatus for handling heavy lids - Google Patents

Description

Patent attorneys Dipl.-Ing. R.! 3 _L tüTZ Dipl-Incj. K. LAWP ^ Ci

Dr.-Ing. R. ES ^ C Γ Z Jr.
β Munich 22, Sioinsdorfstr. 10 2157287

410-17.843P November 18, 1971

ELECTRICITE DE FRANCE (Service National). Paris ( France)

and

COMMISSARIAT AL ¹ ENERGIE ATOMIQUE, Paris, (France)

Method and apparatus for handling heavier

lid

The invention relates to a method and a Device for handling a lid or a cover of a housing containing radioactive products and particularly the handling of the cover of a nuclear reactor vessel. The term "lid" should be used as a matter of course to be understood in the broadest sense and not only include lids made from one piece »but also assembled Structures of which certain parts are movable or detachable compared to the rest.

The containers or housings intended for working with light water nuclear reactors preferably have a

41O- (B 3914.4.3) -Nö-r (7)

20982370727

upper cover with a fairly large diameter, which provides access to the reactor core and in certain cases also to the Heat exchangers permitted. This cover has a very considerable weight, which is the case with a container made of prestressed concrete for high-power reactors reached about 100 tons. This lid is raised at regular intervals, to access the fuel elements, in particular with regard to their recharging as well as to the other organs within the reactor core housing. That The high weight of the lid now makes it difficult and delicate to handle, all the more so than the reactor before under a layer of demineralized water (or a other absorbent liquid) must be set, which is sufficient to the operating personnel when opening of the housing from the radiation originating from the reactor core.

The aim of the invention is therefore a process and apparatus for the handling of such a cover through which very significantly reduces the applied for the lifting and the transverse displacement of the lid forces and existing in classic systems hazard k ren in connection with raising a part of several decatons of weight can be reduced via a suspension and its transport from the usual seat to an alternative place.

The method according to the invention, developed for this purpose, for handling a heavy cover for a housing, which in particular contains radioactive products, is characterized in that a basin surrounding the cover of sufficient dimensions to hold the cover therein

209823/0727

to be able to shift progressively with a liquid which guarantees protection against the radiation of radioactive products, and that you get into one with the Lid to be connected or firmly connected chamber introduces or maintains a fluid of lower density than said liquid in sufficient quantity, in order to give the totality of the lid and chamber an average density close to that of the liquid.

The invention further comprises a device for handling a heavy cover for a housing containing radioactive products, which is characterized by a Basin surrounding the lid of sufficient dimensions to be able to relocate it therein; one with the lid tight connected or connectable chamber; Means for introducing a liquid for protection against the radiations of the radioactive products into the basin; and means of introduction or maintaining an amount of fluid of lesser density than the liquid in the chamber, which is sufficient to give the assembly of the lid and the chamber an average density that of the liquid comes close.

It should be noted that the implementation of the invention The process requires only relatively low-cost changes to the equipment, which at all Cases at nuclear reactors will be necessary. As a matter of fact is the said basin indispensable to the reactor core anyway to be able to cover with a layer of water before handling the fuel for protection of the operating personnel is sufficient. In addition, this basin can be used with the decay or deactivation

209823/0727

Connect or combine container for the radiant fuel elements removed from the housing.

The invention will be based on the following description may be better understood from non-limiting examples of devices according to the invention. The description refers to the attached drawings; it show schematically

Fig. 1 is a vertical section through a first system for handling a lid for a Prestressed concrete housing of a pressurized water type nuclear reactor;

FIG. 2, analogous to FIG. 1, shows a variant of the system shown there and

Fig. 3 shows the upper part of the housing of Fig. 2 and the raised and displaced in evasive position Lid.

Fig. 1 shows a prestressed concrete housing for receiving a Reactor core and possibly heat exchangers with one light water under pressure operated nuclear reactor »This housing comprises a fixed part 10, which is through a lower bottom and a lateral jacket is formed, as well as a removable cover 12, which exposes an opening, whose diameter is of the same order of magnitude like the diameter of the inside of the case 14. During the Reactor operation is the cover by tension members, the

209823/0727

indicated schematically by anchoring cables or rods 16 are restrained in his seat. Housing and cover themselves are not described in detail because they are sufficiently known to the person skilled in the art.

The cover 12 is provided with a vertical ring weir 18 provided, which delimits a chamber 20 with the surface of the cover 12. This ring weir does not necessarily have to be included be firmly connected to the cover 12, but it can also be dismantled in whole or in part in such a way that it can only be appropriately fixed in the intended place before each opening of the housing.

The cover 12 and the upper part of the housing shell are located within a basin 22 which is delimited by a base plate 24 and walls 26. This basin is preferably connected to the storage container (not shown) for the irradiated fuel elements. The base plate 2k or at least a part thereof is preferably calculated in such a way that it forms (or helps to form) an alternative place for the temporary accommodation of the cover, for example in the position shown in phantom in FIG.

An inner projection 27 of the base plate 2k is connected in a sealed manner to the fixed part 10 of the housing via seals 28, which are shown in FIG. 1 are only indicated very schematically. These seals can be permanent in such a way that a layer of demineralized water can be left in the basin during operation of the reactor, which offers a biological protection which is superimposed on that formed by the housing walls. You can

209823/0727

but also provided releasably and only before lifting of the lid.

In the second case, the operations for opening the housing are as follows: The reactor is turned off, the pressure in the housing returned to atmospheric pressure, the fixings of the rods 16 are released and the rods are pulled out if necessary. The latter two Operations are performed by the staff while the pool is still dry when the fixed part and

P the cover of the housing adequate protection from the Offer radiation that is still being emitted by the reactor that has already been shut down. You then put the removable ones Seals 28 and closes the openings of the sockets for the passage of the rods 16. The reactor is then placed under demineralized water, which comes from the reactor's own circuit, via lines not shown can. You fill the basin with a shielding liquid (which is practically demineralized water is formed, although certain light hydrocarbons would also be useful) to that in Fig. 1 through the reference numeral 30 marked level. The connection

fe between the ring weir 18 and the cover 12 must of course be tight so that the chamber 20 is not filled.

The cross-section of the ring weir depends on the weight and the volume of the cover 12 is chosen such that the buoyancy of the totality of cover 12 and chamber 20 is greater is considered to be their weight when the water in the pool reaches a level that is slightly below the top of the Ringwehrs lies. This is on a handling organ

209823/0727

attached, in the arrangement shown in Fig. 1 by an overhead crane 32 is formed. After a possible unlocking of the cover by acting on (not shown) Auxiliary screws or hoists between cover 12 and housing jacket the cover (the apparent weight of which is now very low) is lifted with the aid of the overhead crane. The basin is filled further while lifting the lid in such a way that the water level is close to the The upper edge of the ring weir remains, but cannot run into the chamber 20. If the water then a sufficient one Has reached the level indicated by 34 in FIG one can stop lifting the lid and move it transversely to bring it beyond its rest position to bring to the alternate point. You can then let the water level drop and the overhead crane 32 at the same time press until the cover rests in the position shown in phantom in FIG. 1.

When the cover is put back on, the specified Operations in reverse order, so that it is probably unnecessary to list them again.

It goes without saying that the device just described and its type of application are accessible to numerous modifications. For example, you can let the lid float or, on the contrary, leave it permanently with a low apparent weight. The ring weir can with be provided with additional pumping elements that enable the removal of water if such is accidentally got inside. It can carry organs connected to a closable line that penetrate the lid and allow demineralized water to be introduced into the housing prior to opening.

209823/0727

In addition, the cross-section and height of the ring weir 18 are preferably chosen such that the buoyancy only then the weight of the entirety of the cover 12 and ring weir 18 compensated for when the height of the water in the pool offers sufficient biological protection.

In the device shown in FIGS. 2 and 3, there is again a housing with a fixed part kO, which rests on foundations 4i and has a cover 42. The cover and the upper part of the housing shell are arranged in a basin 52 delimited by a base plate 54 and walls 56. The base plate is in turn provided with an annular inner projection 57 which is connected to the housing jacket of the fixed part 40 via permanent or temporary seals 58.

In the embodiment shown in Figs the chamber 50 through the side surface of the lid 42, a annular cover 49 and a cylindrical jacket 48 limited. The annular chamber formed in this way is open at the bottom and forms a kind of diving bell. Through the lid 42 lead one or more lines 60, which are connected to a system via a flexible pipe 62, with the Compressed air can be introduced from a system 64 or air can be released into the atmosphere. The discharge or the The mouth of the flexible tube 62 is at such a level that the air cannot completely escape.

Before opening the housing, the volume of demineralized water in the housing is brought to the level 66 (FIG. 2) and the water in the basin 52 to the level 65. The lid is then loosened and passed through the pipe 62 and

209823/0727

line 60 pressurized air into chamber 50 while being forced back of the water in it. When enough water has been displaced, the lid 42 is raised together with the ring plate 49 and the cylindrical jacket. The mass of the air contained in the chamber 50 becomes controlled so that it reaches the lower edge of the cylindrical shell 48. This is determined in such a way that then the buoyancy of the entire arrangement is higher than its weight and the center of gravity of the buoyancy or that Metacentre is above the center of gravity.

The supply of air through the line 62 can be maintained because excess air is under the cylindrical Jacket escapes away, whereby the volume of air contained does not change due to occasional leakage losses will.

The cover 42 can thus be displaced by acting on the water level in the chamber 50 (or basin 52) and, if necessary, by connecting the cover to a system for its transport. The cover 42 can also be provided with an auxiliary support structure, not shown in FIGS. 2 and 3, which is supported on the walls 56 and serves to guide the movements of the cover. It can be brought from the position shown fully drawn in FIG. 2 into the position shown in FIG. 3 by bringing the level of the water from 65 (FIG. 2) to 68 (FIG. 3). You can then place the lid at an alternative place, as indicated by dash-dotted lines in Fig. 2, by bringing the water level in the basin back to 6 ^ .

209823/0727

Of course, the invention is susceptible to numerous modifications, including those just described Types of execution are only non-restrictive Examples. Of course, the invention encompasses all variants within the scope of mechanical equivalence.

209823/0727

Claims (1)

Claims /1.yProcedure for handling a lid of a radioactive Housing containing products, characterized in that there is a basin surrounding the lid of sufficient dimensions to contain therein to be able to move the lid, progressively with a Liquid fills that ensures protection against the radiation of radioactive products and that one is in a (r) with the lid to be connected (n) or firmly connected (n) chamber a fluid of lower density than introduces or maintains said liquid in sufficient quantity to cover the whole of the cover and To give chamber a mean density that comes close to that of the liquid. 2. Device for handling a heavy lid a housing containing radioactive products, characterized by a basin (22) surrounding the cover (12) of sufficient dimensions to move it inside; one firmly connected or connectable to the cover Chamber (20); Means for introducing a liquid to protect against the radiation of radioactive products in the pool; and means of induction or uprighting (if applicable) maintaining a fluid of lower density than that Liquid in or in the chamber in 'an amount that sufficient to give the assembly of lid and chamber a medium density that of the liquid comes close. 3. Device according to claim 2, characterized in that 209823/0727 "that the chamber (20) delimited by the cover (12) forming its bottom and by a side wall (18) projecting from the lid fro vertically upwards, such that the entirety of the cover and filled with ¹ air chamber has an average density which is less than that of the liquid, so that its buoyancy is higher than its weight (Fig. 1) " k. Device according to claim 3 »characterized in that the cross section of the wall (i8) is such that the totality of cover (12) and chamber (20) only attains positive buoyancy when the thickness of the liquid layer above the cover seat is sufficient biological Protection against radiation from radioactive products guaranteed (Fig. 1) " 5. Apparatus according to claim 2, characterized in that that the chamber (50) is formed by an annular zone which forms a kind of diving bell which is delimited by a partition (49 »48) provided around the cover and that the means for introducing the fluid into the chamber comprise a flexible conduit (62) which is connected to a Pressurized gas source or the atmosphere can be connected (Fig. 2). 6. Apparatus according to claim 5, characterized in that that the line for introducing or removing the fluid into or from the chamber at such a level leads to the fact that only a part of the fluid can escape from the chamber. 209873/0727 7 «Device according to one of claims 2 to 6, characterized characterized in that the liquid is demineralized water. 8. Apparatus according to claim 7, characterized in that the basin with a storage room for the radioactive Related products « 209823/0727