DD237396A1 - REUSABLE MASS FOR DRY BIOLOGICAL PROTECTION IN THE REACTOR CHEST AND METHOD OF INTRODUCING - Google Patents

Abstract

The invention relates to a filling compound for the dry biological protection as neutron shielding in the reactor shaft of nuclear power plants and a method for introducing into a reactor shaft enclosing container. The aim of the invention is, by influencing the grain band of the serpentinite rock, to find a cheap filling material which is used within a dry mixture which, by virtue of its composition, guarantees a high density and thus a low void content in the container. This is achieved in that the fill mass is a mixture of 60 wt .-% Serpentinitschotter the Kernung 63 ... 90 mm and 40 wt .-% serpentinite rock flour the 0 to 1 mm. The introduction of the fill mass into a steel reactor enclosing the steel container takes place in such a way that the mixture components are introduced separately and in layers and then compacted by vibration to a homogeneous Schuettdichte over the entire filling, combined with the filling of the cavities.

Description

Field of application of the invention

The invention relates to a filling material for dry biological protection as neutron shielding in the reactor shaft of nuclear power plants and a method for introduction into a container enclosing the reactor shaft.

Characteristic of the known technical solutions

A special concrete is known, consisting of a mixture of serpentinite and cement mixed with water.

As a slurry filling material, it is introduced into a prefabricated steel container enclosing the reactor shaft and dried at elevated temperature for about 3 months.

The homogeneity of the bound hydrogen as a moderated constituent in dry biological protection is of particular importance for the neutron flux system of reactor monitoring, so that unevenly distributed or later drying residual water by its hydrogen content disturbs the measuring system. ,

A disadvantage is the complicated, associated with considerable energy supply drying process of the filling compound.

In addition, the excess mixing water of the hardened concrete can only be partially removed.

Due to the lengthy drying process, the construction freedom in the reactor shaft for other technological processes over an unreasonably long period of time is not given.

Also known is a filling compound as a dry bed of serpentinite rock of grain size 0 to max. 4mm.

Due to the considerable void content within the bed, a larger wall thickness for the same radiation protection requirements must be used.

Object of the invention

The aim of the invention is to find a cheaper filling material by influencing the grain band of serpentine split, which is used within a dry bed, which guarantees by its composition a high bulk density and thus a low void content in the container.

Explanation of the essence of the invention

The object of the invention is to optimize the dry bed for the biological protection of reactor systems without additives in order to achieve on this basis an increase in the bulk density, combined with a minimization of the void content. The special requirements for biological protection should be improved under dynamic load.

According to the invention, the object is achieved in that the filling compound is a mixture of 40% by weight of serpentinite rock flour with a grain size of 0-1 mm and 60% by weight of serpentine rubble with a grain size of 63 mm to 90 mm.

The method for introducing this filling material into a steel container enclosing the reactor shaft is carried out by stratified introduction of Serpeiitinitgesteinsmehi and Serpentinitschotter to container filling and by shaking the mixture components, depending on the layer of Serpentinitschotter or Serpentinitgesteinsmehl penetrates into the underlying Schichtteilweise and a homogeneous bulk density over the entire Filling cross-section is achieved, which is measured by means of density probes within the tubes of the ionization chambers.

The layer structure begins with a layer of serpentinite rock flour, to which the triple layer thickness of serpentine rubble is brought and then serpentinite rock flour is filled up again until Vs covers the height of the serpentine rickety

The advantages of the filling material according to the invention and of the method for introducing the same into a steel well enclosing the reactor shaft consist in increasing the bulk density, reducing the processing effort for the filler used by using ballast, reducing the void content to about 200 l / m ³ dry Bed, the increase in the heat transfer value and in the absence of mixing processes.

Due to the advantage of reducing the heat transfer resistance and the void content, the cross-section of the steel container can be reduced while ensuring optimal radiation protection, which leads to considerable steel and bulk material savings.

embodiment

The invention will be explained in more detail below using an exemplary embodiment.

Serpentinite is crushed in grain fractions O ... imm, and 63 ... 90 mm, and in static drying, i. without any energy supply, or similar, freed of water.

For further storage or for transport, the grain fractions are separated and to avoid re-absorption of water in waterproof containers, eg. B. plastic bags, packaged.

The filling compound consists of a mixture of 40% by weight of serpentinite rock flour of particle size O ₁ .. ₁ mm and 60% by weight of serpentine otter of grain size 63 ... 90 mm.

The introduction of the mixture components of the filling material into a steel container enclosing the reactor shaft takes place in the layer structure, beginning with serpentinite rock size of grain size 0 ... 1 mm, to which the triple layer thickness of serpentinite gravel of grain size 63 .. 93 mm is applied and leveled. By arranged on the circumference of the steel container external vibrators, the mixture components are compressed to a homogeneous bulk density over the entire filling cross section.

The bulk density is measured by means of density probes within the tubes of the ionization chamber.

Serpentinite rock meal is filled up to this homogeneous layer and compacted until 80% of the height of the serpentine stout is covered.

The following layer is again serpentine. This process is repeated until the container is filled.

Claims (2)

Invention claim: 1. filling material for dry biological protection in the reactor shaft of nuclear power plants, characterized in that it is a mixture of 40 wt .-% serpentinite rock flour grain size 0 ... 1 mm and 60 wt .-% Serpentinitschotter the grain size 63 ... 90mm , 2. A method for introducing the filling material in a reactor shaft enclosing steel container according to item 1, characterized in that introduced to the tank filling layer by layer serpentine rock dust and serpentine, leveled and by shaking, depending on the layer position of Serpentinite or the Serpentinitgesteinsmehl partially penetrates into the underlying layer , a homogeneous bulk density over the entire filling cross section, which is measured by means of density probes within the tubes of the ionization chambers is reached, starting with a layer of serpentinite rock flour placed on the 3 times the layer thickness serpentine and then again serpentinite rock flour filled and compacted to 80% of the height of the Serpentinitschotters are covered.