EP1512155B1 - Method and device for disposing of a fuel element case of a boiling water reactor - Google Patents

Description

The invention relates to a method for disposing of a fuel box. In addition, the invention relates to a method and apparatus for disposing of radioactively contaminated parts of a boiling water reactor plant.

Components of a nuclear reactor system which come into contact with the cooling water of the primary circuit, are considerably contaminated radioactively and, if they were installed in the reactor core, additionally activated. Due to operational wear, which in particular core components are subject to high levels, it is necessary to expand these parts and replace them with new ones. The removed parts must be conditioned in accordance with strict precautionary measures in order to make them manageable for disposal. Such a wearing part is in a boiling water reactor, for example, a complete fuel element, in its preparation for disposal a method in the DE 199 47 120 A1 is disclosed. But also the embrittled by the high radiation load fuel box of a spent fuel assembly, as he, for example, in Fig. 1a and b is shown in a plan view of the bottom side or on one of the long sides, in itself represents such a wearing part. The wall 2 of such a fuel element box 4 encloses a substantially rectangular cavity 6. The fuel box 4 is open at its ends and is only provided on a front side at opposite corners with support struts 8a, which for fixing the fuel channel 4 on serve a fuel element head, not shown in the figure. In addition, the fuel channel 4 is provided in its lower region with further elements, in the example nubs 8b and outer plates 8c, which are specific to the type of box shown by way of example. In the conditioning of such a fuel element box this is usually pressed and then cut into small pieces. However, such a procedure is expensive.

The invention is based on the object to provide a method for disposing of a fuel assembly of a boiling water reactor system, which is simplified compared to the procedure mentioned in the prior art. In addition, the invention is based on the object to provide a method for disposing of radioactively contaminated parts of a boiling water reactor system and an apparatus for performing this method.

The first object is achieved according to the invention with a method having the features of claim 1. According to these features, the fuel assembly is stabilized with a preassembled support structure by inserting the support structure into the fuel assembly. Furthermore, the fuel channel box is closed on one of its end faces by means of a base plate arranged on the support structure and serving as a base. In other words, the fuel assembly is not destroyed but provided with one or more supportive components that give it a higher strength or stability. For a costly pressing and disassembly of the fuel assembly is no longer required and its disposal simplified. A prepared in this way for the disposal or conditioned fuel assembly can also also as a transport container for other parts to be disposed of and correspondingly conditioned parts, in particular for core components or for small-volume so-called core scrap to be used.

In an advantageous embodiment of the method, the fuel assembly is provided with a carrying handle. Thereby, it can be handled in the same way with the same facilities as they are provided for the handling of the fuel assembly.

With respect to the second-mentioned method, the object is achieved according to the invention with the features of claim 3. Since the stabilized fuel assembly is used as a transport container for more radioactively contaminated parts, its particularly cost-effective disposal is possible together with the core scrap.

In an advantageous embodiment of the method, the leaves are separated from a control element to be disposed and introduced into the stabilized fuel assembly. Since the longitudinal and transverse expansions of the leaves of a control largely correspond to those of a fuel box these can be accommodated in a fuel box extremely space-saving, which can accommodate the leaves of three controls in this way.

In particular, the support structure divides the fuel assembly with an internal partition in at least two sub-areas, which is supported during insertion of the leaves in one of the sub-areas. As a result, the filling of the fuel channel is facilitated.

With regard to the device, said object is achieved according to the invention with the features of claim 6. Advantages of the device according to the invention and advantages of the claim 6 respectively subordinate claims will become apparent mutatis mutandis from the claims corresponding to each corresponding method claims.

• Fig. 1a und b eine Draufsicht auf die Bodenseite bzw. auf eine Längsseite eines Brennelementkastens,
• Fig. 2a und b eine Draufsicht auf die Bodenseite bzw. auf die Längsseite einer erfindungsgemäßen Tragstruktur,
• Fig. 3a und b eine Draufsicht auf die Stirnseite bzw. auf eine Längsseite des mit der Tragstruktur stabilisierten Brennelementkastens,
• Fig. 4a und b eine Draufsicht auf die Stirnseite bzw. auf eine Längsseite des mit den Blättern von Steuerstäben gefüllten Brennelementkasten.

For further explanation of the invention reference is made to the embodiment of the drawing. Show it:

• Fig. 1a and b a plan view of the bottom side or on a longitudinal side of a fuel assembly,
• Fig. 2a and b a plan view of the bottom side or on the longitudinal side of a support structure according to the invention,
• Fig. 3a and b a plan view of the front side or on a longitudinal side of the stabilized with the support structure fuel box,
• Fig. 4a and b a plan view of the front side or on a longitudinal side of the filled with the leaves of control rods fuel bundle box.

According to FIGS. 2a, b For example, the support structure 10 comprises a base plate 12 which carries a partition plate 14 extending perpendicularly to the flat side of the base plate and in particular is welded thereto. The partition plate 14 has a longitudinal extent which is greater than the longitudinal extent of the fuel channel 4 and is provided at its side facing away from the base plate 12 free end with a recess 16 so that a carrying handle 18 is formed. Transverse to the partition plate 14 and perpendicular to the base plate 12, a spacer plate 20 is fixed on this, which passes through the provided in this area with a slot 22 partition plate 14.

FIGS. 3a, b For this purpose, this is introduced from the bottom side into the empty fuel element box 4 until the base plate 12 closes the empty fuel element box 4 and forms a bottom. The carrying handle 18 then protrudes beyond the fuel channel 4. It can also be seen in the figure that the fuel element box 4 is subdivided by the separating plate 14 into two subregions 42, 44.

According to FIGS. 4a, b are in the stabilized with the support structure 10 fuel assembly 40 control rod blades 24 inserted, which have been separated in a previous step from to be disposed of tax bars and of which in FIG. 4b a halved by the previous decomposition bracket 26 is shown a carrying handle.

The spacer plate 20 serves to support the control rod blades 24 so that the space used to hold the control blade blades 24 is free from interfering internals located at the bottom of the fuel box 4. At the same time four sub-chambers 46 are formed below the control blades 24, which can be used to hold small-volume core scrap.

LIST OF REFERENCE NUMBERS

2

wall

4

Fuel channel

6

cavity

8a

support struts

8b

burl

8c

plate

10

supporting structure

12

baseplate

14

separating plate

16

recess

18

handle

20

spacer plate

22

slot

24

Control rod blades

26

hanger

40

Fuel channel

42.44

subregions

46

subchambers

Claims (8)

1. Method for the disposal of a fuel assembly box (4) of a boiling-water reactor system, in which the fuel assembly box (4) is stabilized with a prefabricated carrier structure (10), by the carrier structure (10) being introduced into the fuel assembly box (4) and in which a face side of the fuel assembly box (4) is closed with the aid of a base plate (12) arranged at the carrier structure (10) and serving as a base.
2. Method according to Claim 1, in which the carrier structure (10) is provided with a carrier handle (18).
3. Method for the disposal of radioactively contaminated parts of a boiling-water reactor system, in particular of integrated core parts, in which a fuel assembly box (40) stabilized according to any one of the preceding claims is used as a transport container.
4. Method according to Claim 3, in which the control rod blades (24) of a control rod which is to be disposed of are separated and conveyed into the stabilized fuel assembly box (40).
5. Method according to Claim 4, in which the carrier structure subdivides the stabilized fuel assembly box (40) with an interior partition wall (14) into at least two part areas (42, 44), which are supported on the introduction of the blades into one of the part areas (42, 44).
6. Device for the disposal of radioactively contaminated parts of a boiling-water reactor system, in particular of integrated core components, with a fuel assembly box (40), which is stabilized with a prefabricated carrier structure (10) introduced into the fuel assembly box (40) and serves as a transport container, wherein the carrier structure (10) comprises a base plate (12) which closes the fuel assembly box (4) on one side.
7. Device according to Claim 6, in which the carrier structure (10) is provided with a carrier handle (18).
8. Device according to Claim 6 or 7, in which at least one partition plate (14) is arranged on the base plate (12) of the carrier structure (10) such as to be perpendicular to it, which subdivides the interior of the stabilized fuel assembly box (40) into at least two part areas (42, 44).

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