Pressurizer
The pressurizer is a special vessel in the reactor cooling circuit of a pressurized water reactor . Its main task is to apply the design pressure to the reactor cooling circuit and to compensate for temperature-related volume fluctuations (sufficient coolant supply for various transients , e.g. full load reactor shutdown ). The connection is made via the so-called volume compensation line to one of the loops.
The pressurizer is the only point in the reactor cooling circuit at which the operational boiling state prevails, i. i.e., both water and steam are present.
construction
Heating rods
There are heating rods at the lower end of the pressurizer. These are used to generate the vapor cushion in different heating levels. The supply line from the volume compensation system (volume compensation line) is also attached here.
Spray system
Spray lines and an auxiliary spray line from the volume control system run into the top of the pressurizer. Each of these lines opens into a spray box with full cone nozzles inside the pressurizer .
To lower the pressure, the main coolant is sprayed in via the spray nozzles. Some of these sprays are in continuous operation to enable both the boric acid concentration to be adjusted and the pipeline to be preheated. Since this would lower the temperature and thus also the pressure, part of the heating system (basic heating) must be operated continuously at the same time.
Spray shirt
In order to prevent material fatigue on the inner wall of the container when the cold medium is sprayed into the hot container, a pressure container has a so-called spray shirt. This is a hollow sheet metal cylinder that is attached at a distance from the inner wall of the container and prevents direct contact between the spray medium and the inner wall of the pressurizer.
Safety valves / relief valves
Like almost every pressure vessel, the pressurizer must also be secured against inadmissible overpressures. This is done using the pressurizer safety valves, which are attached to the top of the pressurizer and allow steam to escape into the pressurizer blow-off tank. Parallel to the safety valves, there is a shut-off blow-off valve, which can be used to blow off steam from the pressurizer by hand.
Due to its importance in terms of safety, the level of the pressurizer must be constantly monitored during operation. Both too high and too low a fill level are criteria for a reactor shutdown.
Web links
- Description of the manufacturer AREVA NP ( Memento from September 27, 2007 in the Internet Archive )