DE1943657A1 - Prestressed concrete pressure vessel for nuclear reactors - Google Patents

Description

Prestressed concrete pressure vessels for nuclear reactors

In the case of pressure vessels for atomic nuclear reactors made of prestressed concrete two properties of concrete are very disadvantageous. On the one hand, the compressive strength of concrete is such values that the walls of the pressure vessel must be made considerably thicker than would be necessary for radiation reasons. This results in increased temperature stresses and a considerable amount of space in the building. On the other hand, concrete has high load and temperature creep rates, which is particularly disadvantageous for prestressed concrete components.

However, it is possible to compensate for these disadvantages to a large extent by means of appropriate post-treatment. However, there is one Post-treatment for in-situ concrete, i.e. if the container is cast in one piece on site, is not possible.

The invention is therefore based on the object of a reactor pressure vessel To create usable concrete that has both high cold and hot compressive strength and a low one Temperature creep rate. Only when using · appropriately compact Such post-treatment is possible for prefabricated parts for the prestressed concrete pressure vessel. The invention therefore exists in that the precast concrete during solidification a temperature below room temperature and a exposed to increased pressure. It is possible to use both the entire pressure vessel from the appropriately treated To create prefabricated parts as well as those made of in-situ concrete

109810/1902

-2-

- 2 - PLA 69/1232

Pressure vessels only places particularly stressed, such as tendon anchorages, supports for ring tendons or Equipping similar highly stressed components with corresponding prefabricated parts.

The essential criteria for the strength of the concrete are to be found in the cement stones. In the cement paste that the aggregate grains enveloped, the individual cement clinker particles are more or more after mixing, depending on the selected water-cement factor less separated by water particles. Calcium hydroxide is dissolved in this water and precipitates if it is oversaturated. Of the Cement clinker grains grow from strength-building hydration " products into the water-filled rooms. With the correct choice of the water-cement ratio, gel structures then form a supporting structure. The closer the cement grains are to one another in the initial state, the more stable the dressing will become; because the non-hydrated areas give off their water and those through it The resulting capillary pores reduce the strength.

Therefore, a very high quality concrete must have a water cement factor of less than 0.4. It has been found that such a concrete can be optimally compacted only by external pressure. If the temperature is lowered at the same time, i.e. in the solidification phase, this causes a delay in the chemical reaction and thus a better compression. The selected lower temperature should be around + 5 ° C and the external pressure around 20 kp / cm .

The main advantage of concrete treated in this way is its increased strength. In addition, the load and temperature creep rates, which are extraordinarily unpleasant for prestressed concrete, can be at least partially anticipated by the previously described precompaction.

1 claim

-3-1 09810/1902 ^fc

Claims (1)

- 3 - PIA 69/1252 Claim Prestressed concrete parts for pressure vessels, in particular for Atoine nuclear reactors, characterized in that the precast concrete parts during the solidification at the same time one below the Be exposed to a temperature lying at a low temperature and an increased pressure. 109810/1902