Patent Number: 050283782
Section: description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT In the Figure, the abbreviations have the following meanings: HTR --high temperature reactor; PA1 GRA --gas purification installation; PA1 T.sub.HG --hot gas temperature; PA1 T.sub.HK --cold gas temperature; PA1 P.sub.HE --cooling gas pressure (helium is used as the cooling gas); PA1 SBB --reinforced concrete pressure vessel; and PA1 LKS --liner cooling system. The time intervals given indicate how much time is available for the individual measures to limit the damaging effects of an extreme disturbance to an acceptable magnitude and respectively to place the plant into a controlled state. With reference to the sole figure, the description and operation of the preferred embodiment of the claimed invention is as follows. In an event of a unlikely accident in which certain characteristic process parameters become appreciably higher than those necessary to trigger the reactor protection system, the safety system of the present invention may be actuated in an electronic fashion, physical fashion or manual fashion. The safety system 10 is intended for use in a gas cooled high temperature reactor system 100 having a reactor 110 housed together with steam generators in a prestressed concrete pressure vessel 120, which can be shut down by abosrber rods, and equipped with a reactor protection system (not shown) to actuate an emergency shutdown. Safety system 10 includes an accident instrumentation apparatus 20 which is located in high temperature reactor 110 to monitor certain characteristic process parameters such as hot gas temperature, cold gas temperature and cooling gas temperature. The parameters are independent of the values used for the reactor protection system and have limiting values which are appreciably higher than those values for the reactor protection system. Safety system 10 further includes an actuation system 30 having an electronic evaluation mechanism 40 for interrupting the supply of power for cooling gas blowers, fuel water pumps and absorber rod holding devices if the process parameters exceed their predetermined limiting values. Actuation system 30 also includes sensor devices 50 such as temperature or pressure sensitive devices located in a primary loop to physically interrupt the power supply to the cooling gas blowers, fuel water pumps and absorber rod holding devices. Actuation system 30 also includes a central emergency switch mechanism 60 for manual interruption of the power supply to the cooling gas blowers, feed water pumps and absorber rod holding devices in case of a safety system danger signal. Safety system 10 further includes a manually actuated mechanism 70 for reducing the pressure in the reinforced concrete pressure vessel in case of a safety system danger signal. The safety system 10 further includes a liner cooling system 140 associated with the reinforced concrete pressure vessel 120. A manual device 141 is actuated to feed cooling water to liner cooling system 140 upon receipt of a safety system danger signal. Parameter sensor devices 50 may be temperature sensitive devices such as fuses or bimetallic strips. The temperature sensor devices may be located anywhere along the high temperature reactor but are preferably located above and under the reactor core. The parameter sensor devices may also include pressure sensitive devices such as pressure transducers or pressure contacts.