Loading machine for transferring closely adjacent elongate...

Induced nuclear reactions: processes – systems – and elements – Handling of fission reactor component structure within... – Refueling machines

Reexamination Certificate

Rate now

  [ 0.00 ] – not rated yet Voters 0   Comments 0

Details

C376S269000, C376S270000, C376S271000

Reexamination Certificate

active

06359953

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to the handling of elongate articles, preferably fuel elements. The fuel elements, together with their control elements, are disposed so as to be directly adjacent to one another, in a so-called narrow position, in the pressurized water reactor core of a nuclear power station. When stored, the fuel elements are mounted at a distance from one another, in a so-called wide position, in a fuel element storage rack in the fuel element storage pool of the nuclear power station. In the case of a change of fuel element, spent fuel elements have to be transported out of the reactor core into the storage rack and fresh fuel elements have to be transported out of the storage pool into the reactor core. The invention relates, in general terms, to a loading machines or more specifically a refueling machine, for handling elongate articles, the longitudinal axis of which is oriented in a geodetically vertical direction. A plurality of these articles is disposed so as to be directly adjacent to one another in a so-called near position and so as to be at a slight distance from one another in a so-called wide position. The loading machine serves, in particular, for transporting such articles out of a closely packed bundle of these articles to a workplace or set-down location or storage location. Conversely, the loading machine also serves for combining such set-down articles to form a closely packed bundle.
The preferred use of the invention for the handling of fuel elements and control rods in a nuclear power plant is primarily described below, although this does not rule out other ways of using the invention.
In nuclear power stations with light water reactors, the reactor core is accommodated in the reactor pressure vessel. In this case, the reactor core has a plurality of fuel elements which are of essentially elongate parallelepipedal shape and are oriented geodetically vertical so as to be closely adjacent to one another. In order to control the nuclear reaction, a plurality of these fuel elements have control rods which are introduced into the fuel elements through guide tubes contained in fuel elements.
During the operating period of a nuclear reactor, the nuclear fuel contained in the fuel elements is consumed by being burnt up, with the result that the fuel elements have to be exchanged from time to time. Since the burn-up of fuel elements depends on their position in the reactor core, the fuel elements are not consumed simultaneously. Fuel elements not burnt up completely are usually transferred in the reactor core. The exchange and transfer of fuel elements takes place after an operating cycle of the power plant of several (for example, 12 or 18) months.
To change a fuel element, the reactor has to be shut down and made pressureless. By demounting the pressure vessel cover and removing various internal fittings, the reactor core becomes accessible from above. This is carried out, with the reactor pool flooded, in order to obtain water shielding for the exposed reactor core. A manipulating bridge, together with a gripper suspended in a guide mast, can then be moved over the flooded fuel element storage pool and the reactor space. Each position in the storage rack and reactor core can be approached with the aid of a positioning system, that is adjusted or calibrated according to coordinates.
In order to handle fuel elements and control rods and also throttle devices, which close off the control rod guide tubes of those fuel elements having no control rods, it is possible, for example, to use a so-called double gripper, such as is described in Published German Patent Application DE 17 64 176. This double gripper is vertically movable and is equipped with a control rod gripper and a fuel element gripper, each of which can be operated independently. The double gripper is provided within a guide mast fastened to the manipulating bridge. Disposed within the guide mast is a centering bell surrounding the double gripper. This device is telescopic, in such a way that the centering bell can be moved out of the guide mast. The centering bell centers the double gripper above the fuel element to be gripped, specifically by coupling to fuel element centering devices, which are adjacent to the fuel element to be gripped. The double gripper is moved out of the centering bell in order to grip a fuel element or its control rods. After the double gripper has gripped a fuel element or its control rods, the double gripper, together with the gripped fuel element or the gripped control rods, is moved into the centering bell, and the latter, in turn, is moved into the guide mast. The fuel element can then, through the use of the manipulating bridge, be transferred in the reactor core or delivered to a fuel element storage rack. Conversely, a fuel element can be gripped from a fuel element storage rack and delivered to the reactor core.
The duration of the exchange of a fuel element constitutes a substantial cost factor since the nuclear power station is shut down during this time. moreover, during the change of a fuel element, the operation personnel is exposed to radiation.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide a loading machine for transferring elongate articles, such as fuel elements, and a corresponding method for transferring fuel elements which overcome the above-mentioned disadvantages of the heretofore-known machines and methods of this general type and which shorten the time necessary for changing the fuel element.
With the foregoing and other objects in view there is provided, in accordance with the invention, a method for simultaneously transferring two fuel elements in a nuclear power station, the method includes the steps of:
providing a loading machine having a mast divided into two mast parts provided parallel to one another and movable horizontally relative to one another, and the loading machine having respective grippers and lifting devices for raising and lowering two fuel elements in the two mast parts;
positioning the loading machine over a reactor core or a storage rack of a nuclear power station; gripping each of the two fuel elements and lifting each of the two fuel elements into a corresponding one of the mast parts;
positioning the loading machine, together with the two fuel elements lifted into the two mast parts, over the storage rack or the reactor core in the nuclear power station;
changing a mutual spacing distance between the two fuel elements by moving the two mast parts relative to one another; and
lowering the two fuel elements out of the mast parts and into the storage rack or the reactor core.
In other words, the method according to the invention makes it possible to transfer fuel elements, for example between the reactor core (narrow fuel element spacing) and the fuel element storage rack, a workplace for inspection or another set-down location (widened fuel element spacing, possibly a changed orientation). In this case, a plurality of fuel elements, which are disposed or are to be disposed next to one another in the reactor core, are simultaneously or successively lifted out of their initial position and drawn into a hollow mast which is formed of a plurality of parts movable relative to one another. Each fuel element is guided and held on its own part of the mast. Subsequently, the parts of the mast, together with the fuel elements held in them, are transported jointly to a location in the power station at which they are lowered out of the parts of the mast and set down in a final or ultimate position. The mast parts (including the fuel element in each case held on them) are displaced relative to one another and rotated about a longitudinal direction of the corresponding mast part before or after transport, in such a way that the fuel elements acquire the same spacing and the same orientation relative to one another as are desired for their ultimate position.
The orientation of at least one fuel element in the initial position may be different from that in the ultimate or fin

LandOfFree

Say what you really think

Search LandOfFree.com for the USA inventors and patents. Rate them and share your experience with other people.

Rating

Loading machine for transferring closely adjacent elongate... does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Loading machine for transferring closely adjacent elongate..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Loading machine for transferring closely adjacent elongate... will most certainly appreciate the feedback.

Rate now

     

Profile ID: LFUS-PAI-O-2838665

  Search
All data on this website is collected from public sources. Our data reflects the most accurate information available at the time of publication.