FR2511540A1 - INTEGRATED HEAD ASSEMBLY FOR REACTOR OF CURRENT TYPE - Google Patents

Abstract

INTEGRATED HEAD ASSEMBLY FOR CURRENT TYPE REACTOR. THIS ASSEMBLY 10 COMBINES VARIOUS ELEMENTS AND SUB-ASSEMBLIES OF THE UPPER STRUCTURE OF A REACTOR, SO THAT THIS COMBINED ASSEMBLY CAN BE REMOVED IN A SINGLE BLOCK FROM THE REACTOR TANK. THE ASSEMBLY 10 INCLUDES THE HEAD 18 OF THE PRESSURE TANK, THE SHIELDED COOLING ENCLOSURE 20, THE DRIVING MECHANISMS 22 OF THE CONTROL BARS, THE SHIELD 14, A LIFTING DEVICE, THE HOIST DEVICES 38 AND A ASSEMBLY 28, 30 FORMING A CABLE PATH. APPLICATIONS: ESPECIALLY TO THE CHARGING OF CURRENT TYPE REACTORS.

Description

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  Integrated head assembly for conventional reactor type.

  The present invention relates to the preparation of

  of a nuclear reactor, and it relates in particular to a combination of

  new elements of a conventional reactor, which can easily be

  the reduction of the reloading time.

  The term "conventional reactor" is used in this

  description to describe the type of nuclear reactor that is used

  today in industrial operation.

  The time required to remove the superstructure of a reaction

  The current type of nuclear reactor makes it impractical to frequently recharge the reactor Because of the structural and safety functions performed by the internal parts of a reactor, various elements are assembled together.

  to each other so as to ensure their solidarity during the

  therefore, in order to be able to dismantle the parts

  of the reactor, each element or subassembly

  to be disjoined individually from another element or subassembly, from

successive step.

  This preparation that requires a lot of time, starts with the

  disconnection of the cables connecting the drive mechanisms of the bar-

  order to control the reactor After the removal of the isolation

  the head of the tank, the conductors of the instrumentation thermocouples are disconnected individually The nuts of the studs of the tank are loosened with a special tool, and the studs and nuts are then removed from the flange. of the tank Guide pins are placed in several stud holes to ensure proper alignment of the

  head when refitting and other stud holes are clogged.

  The head of the reactor vessel is deposited by means of a fixed crane.

  manence and slightly raised while the reactor cavity is flooded

  once the head has been deposited, the trees

  control rods are detached individually from the assemblies

  control of the bar clusters, which remain in the heart Finally, the upper internal parts and the drive shafts of the bars of

  control are lifted from the reactor vessel using a device from the

  the internal parts of the reactor This last lifting discovers the heart

of the reactor.

  This painful removal procedure is reversed for the replacement of the elements after reloading the reactor. The complete process

  reloading takes about three to six weeks to be terminated.

  The evaluation of the cost, as a function of the reactor shutdown time, of the recharging of a nuclear reactor of the current type, constituted a

  important economic reason for reducing the time needed to recharge

  The efforts that followed resulted in the construction of a new reactor called a "fast-charge reactor". This embodiment is generally described in US Pat. No. 4,158,599.

  involves the unification of all the elements and subsets of the super-

  nuclear reactor structure into a single integrated head assembly This

  integrated head assembly can be lined then with all cables and sup-

  cable ports that remain attached, as described in US Patent

  No. 3 836 430, to discover the reactor core.

  U.S. Patent No. 3,836,429 describes the unification of

  the superstructure of a nuclear reactor in order to achieve

  seems to be integrated into the fast charging reactor.

  reactor, all elements and subassemblies that were individually detached from the reactor vessel of the current type, remain

  attached to the closing head of the fast-charging reactor vessel.

  These elements and subassemblies include all cables,

  associated with all upper internal parts, such as

  the top support plate, the support columns and the top plate

  heartbeat, the control rod drive mechanisms and the control rod drive shafts The control rod clusters are also removed because they are part of the set of

  integrated head of the realization with fast reloading.

  The fast-charging reactor involves significant structural changes compared to the construction of the reactor of the

  current type, in order to facilitate the fixing of all the parts

  the upper end of the tank, structurally

  The result is that the fast charging reactor can not be achieved by a modification of existing reactors of the current type.

  associated with relatively long refueling times, for the reactors

  in operation and those currently under construction.

  Accordingly, the main object of the present invention is to provide an integrated head assembly for a reactor structure, which allows both quick reloading and compatible realization.

  with the structure of a reactor of the current type.

  To achieve this object, the present invention consists of a

  integrated reactor head assembly, intended to reduce the time required

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  this involves the dismantling and reassembly of a reactor vessel of the

  This head assembly includes an integrated head closure assembly of the reactor vessel, reactor pressure, control rod drive mechanisms for adjusting the position of the control rod clusters at the same time. inside the reactor core; a shielded cooling jacket which surrounds the driving mechanisms of the control rods and which maintains inside a cooling ambient medium; a shield for providing lateral support to the control rod drive mechanisms and for preventing ejection of these control rod drive mechanisms; means for attaching a hoist crane to said head assembly for raising and lowering said head assembly to the reactor vessel; a plurality of vertical lift rods connecting the lifting crane attachment means to the closure head to provide structural support to the head assembly; several hoist devices for handling dowel pulling tools and dowel removal tools; means for supporting these hoist devices, a plurality of cooling fans attached to the shielded cooling jacket for directing cooling air flow to

  the inside of the shielded cooling envelope; a strong set

  a cable runner for supporting the drawn cables between the head assembly and a maneuvering floor, the cable tray assembly being rapidly separable from the head assembly and including a connection plate facilitating rapid separation of the lead assembly; ropeway assembly and head assembly, and a platform for supporting

  cables between the connection plate and the points of entry into the

  armored cooling jacket.

  Thanks to the arrangement according to the present invention, the time required for reloading a reactor of the current type, is substantially reduced by the use of an integrated head assembly which unifies a large number of elements and subsets of the reactor superstructure, which can be removed from the reactor vessel in a single lifting operation.

  The present invention will be well understood on reading the

  following description made in connection with the attached single drawing which re-

  presents a perspective view of the integrated head assembly, the view being

  cut to a suitable place to reveal details.

  The fundamental elements of reactor operation, con-

  encircled in the present invention, are a pressure vessel head with

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  driving mechanisms of the control rods, a device for

  lifting, a shield, lifting rods, an armored

  cold, a cable trays and cables, cooling fans,

  chilling, an operator station, and hoist devices

  detailed description and function of these various elements are given

  in the prior art and they will not be repeated herein.

  The following description relates to a combination of these elements having

  As a result, an improved integrated head assembly for a reactor of the current type. It should be noted firstly that the present invention, embodied in the form of an integrated reactor head assembly of the conventional type, does not relate to a set of upper internal portions or control rod assemblies, as is the case for the fast-loading reactor head assembly mentioned above, because

  the addition of these subassemblies would require significant modifications

  The structure of the reactor vessel of the current type.

  The figure illustrates an integrated head assembly for the current type reactor A tripod device 12 for lifting the head is articulated

  on a shield assembly 14 The latter is supported by three

  16 which are attached to the head 18 of the reactor vessel.

  seems 14 forming shield usually consists of a heavy plate

  reinforced steel to retain and intercept the driving mechanisms

  control bars in case of significant difficulty.

  A shielded shell 2 Q cooling is mounted directly-

  on the upper part of the head and surrounds the mechanisms 22 which control the movement of the control bar clusters in and out of the core.

  main support structure of the integrated head assembly, and

  me an enclosure that provides a cool environment for

  control rod drives 22 Fans 24 from

  cooling are mounted directly on the shielded casing 20 of

  Cooling 16 lifting rods are anchored in the glass envelope

  20 to provide additional rigidity to the structure and to transmit the lifting forces of the shield 14 to the head 18 of the vessel. Cables 26 coming from the upper part of the control rod drive mechanisms 22, surround the upper part of the integrated reactor head assembly 10 of the current type and are connected to a connecting plate 28 located on the side of the structure Coming from the connection plate 28, the cables follow a cable path 30

  to their respective output connections.

  The cable path is shorter than the quick-charge reactor cable path, so as to conform to the part geometry of the current-type reactor installations. The cable path is supported at the end of the reactor by the shielded cooling jacket 20 and at the other end, by supports placed on a wall of the steam generator (not shown) during the operations

  reloading, the cables 26 are disconnected from the plate 28 of conne-

  xion and stored on the path 30 to cables can then rotate

  the cable path 30 at the end of the maneuvering floor, in a

  storage position away from the reactor vessel. This provision differs

  the layout of the quick-charging reactor cable raceway in which the arrangement within the security envelope makes it possible to

  leave the cable path attached to the structure of the head during

reactor loading.

  The shielded cooling casing 20 is made up of four

  sections that are bolted to each other, unlike

  the shielded envelope in three sections carried out in the refill reactor

  A lower armored envelope 20a, or first section,

  is bolted directly to the upper part of the head 18 of the tank.

  The lower armored envelope 20 has several inspection doors 32

  giving access to the isolation of the head of the tank and the columns (not

  presented) instrumentation thermocouples, for maintenance purposes This lower shielded casing 20 also supports the baffle system (not shown) surrounding the drive bar drive mechanisms 22.

  command and which is used to direct the flow of cooling air

dissention.

  An intermediate shielded casing 20b is bolted to the upper portion of the lower armored casing 20a. This section supports the baffle system and the support structure 34 of the hoist devices. This support structure 34 of the hoist devices comprises two

  runways surrounding the periphery of the armored envelope

  2 Ob External raceway supports trolleys

  main 36 mounted on hoist devices 38 A roadway

  the inner part acts as balancing support for the pa-

  lan 38 These hoist devices 38 are used to maneuver the tools

  bolts and dowel removal tools during opera-

reloading rations.

  An upper armored envelope 20 c, bolted to the upper part

  upper of the intermediate shielded casing 20b, supports the baffle system (not shown) and several cooling fans 24 of the drive mechanisms, control rods These cooling fans 24 circulate air inside. of the envelope

  shielded to remove lost heat from the drive mechanisms 22

Tra Inement of the control rods.

  A platform 20 d that surrounds the periphery of the blister envelope

  20 c, is used to support the power supply devices.

  The cables from the drive rod and thermocouple drive mechanisms 22 (not shown) are fed on the control rods and the cables 26 of the instruments.

  along supports (not shown) to the support platform 20 d.

  All cables converge to a connection plate 28 which connects the

  path 30 & cables to the support platform 20 d use of the

  support form 20 d and the connection plate 28 facilitates the separation of

  The rapid assembly and reunion of the cableway and the head assembly

  This process is unnecessary in the case of the fast charging reactor. The three vertical lifting rods 16, articulated on the head 18 of the tank, are fixed on the shielded casing 20 for cooling

  at two points in their length. These lifting rods 16 are used to convey

  put at the head 18 of the tank the lifting force applied by a crane to the assembly 14 forming shield The lifting rods 16 can move vertically relative to the shielded envelope 20 but any displacement

  horizontal is impossible for them A round head formed at the upper end

  42 of the lifting rods 16 serves as guidance during the descent of

  the shield assembly 14 on these lifting rods 16.

  The assembly 14 forming a shield comprises a flat plate circulating

  Figure 44 which is bolted to the lifting ears 46 attached to the lifting device 12 The plate / 44 is perforated with several chamfered holes 48

  allowing the passage of the extensions 50 of the casings of the drive mechanisms

  This mounting provides lateral support for

  control rod mechanisms 22 and prevents a

  any of the mechanisms 22 does not penetrate the security envelope (no

  shown) in the event of a significant rupture The holes 48 drilled in the en-

  14 shields according to the present invention, are chamfered to facilitate the operation of implementation The realization of the plate

  bolted plate of the integrated head assembly 10 differs from the shield

  Egg box die, used in the prior art.

  The bolted flat plate improves the manufacturability of the assembly 14, provides the operator with a safer and more practical work plan, and addresses some of the requirements for welded constructions (American Society of Mechanical Engineers, Code Tanks under

  and Chaudière, section III).

  An operator station 52, bolted directly to the shield plate 44, provides safe and convenient access to the device eye 12.

  hoist to pass the hook (not shown) of the column crane.

  The integrated head assembly therefore provides, in the form of a

  simple and compact system, a system which reduces reactor downtime and decreases manpower requirements by reducing the number of operations required to assemble and dismount the reactor vessel;

current type when reloading.

  The present invention is not limited to the exemplary embodiments

  described above, it is, on the contrary, likely to

  laughing and changes that will occur to those skilled in the art.

R E Y E N D I C A T IO N S

  1 Integrated reactor head assembly for reducing the time required to dismantle and reassemble a reactor vessel of the conventional type during refilling operations, said head assembly being characterized by comprising an integrated mounting of the head (18)

  reactor pressure vessel to seal the reactor

  ve of the reactor; mechanisms (22) for driving the control rods

  to adjust the position of the control rod clusters inside the reactor core; a shielded casing (20) for cooling

  surround the drive rod control mechanisms (22) and

  keep an indoor environment cool; a shield (14) for providing lateral support to the control rod drive mechanisms (22) and for preventing ejection of said control rod drive mechanisms (22); means (12) for attaching a hoist crane to said head assembly for raising and lowering said head assembly to the reactor vessel; a plurality of vertical lifting rods (16) connecting the hoist crane attachment means to the closure head to provide structural support to the head assembly a plurality of hoist devices (38) for operating the stud clamping tools and dowel removal tools; means (34,36) for supporting said hoist devices (38); several fans (24) of

  cooling on the shielded cooling casing for

  set the cooling air flow to the inside of the enclosure.

  armored shield (20) for cooling; an assembly (28, 30) forming a path

  cables for supporting the cables drawn between the head assembly and a plane

  expensive maneuvering arrangement, this cable race assembly (28, 30) can be separated quickly from the head assembly and includes a connection plate (28) to facilitate rapid separation of the assembly (28, 30) forming ropeway and head assembly; and a platform (30) for supporting the cables between the connection plate and the

  penetration into the shielded cooling casing.

  2 Integrated reactor head assembly according to claim

  1, characterized in that the shielded shielding casing (20) comprises a plurality of sections (20 a, 2 Q O b, 2 Qc) which are stacked one at a time.

  on others and bolted together; and that the inferior section

  20 (a) of this shielded cooling jacket (20) comprises a number of inspection doors giving access to the internal apparatus

maintenance purposes.

  3 Integrated reactor head assembly according to one of the

  vendications; 1 QU 2, characterized in that the shield (14) comprises a flat plate perforated with several chamfered holes to facilitate the introduction of the shield on the drive mechanisms of the bars of

  control; and in that this shield constitutes the upper part of the

  encircled by the bli'ndée cooling envelope.

  4 Integrated reactor head assembly according to one of the

  sales 1, 2 or 3, characterized in that the means (12) for attaching a lifting crane to the head assembly comprises a tripod lifting device attached to the shield (14), said lifting device having an eye

  1 Q at the top of the tripod to pass the hook of the hoist crane.

  Integrated reactor head assembly of any one

  Claims 1 to 4, characterized in that the vertical rods

  (16) have at their upper end a round head (42)

  which facilitates the establishment of the shield (14) on these rods.

  6 Integrated reactor head assembly of any one

  Claims 1 to 5, characterized in that the means (34, 36)

  for supporting the hoist devices (38) comprise two paths

  centric bearings that surround the periphery of the armored envelope

  (20) cooling to which they are attached.