VI. The means to report anomalies
From Intamap
VI. The means to report anomalies
The alarm system implemented in the gamma dose rate measurement network has been designed to alert the staff member on duty on a permanent basis, every hour a day, every day a year. Once the staff member on duty has been alerted he has to start the evaluation procedure within 1 hour. All people which are staff members are living in the Freiburg area. In the case of a network internal alert they have to evaluate the situation at the office or at home. Always 2 persons are on permanance in parallel, a third group is operational at the backup service center in Berlin. They all are equiped with laptops allowing the situation to be analysed also from at home. The alarms reported may be due to radiological alerts (early warnings) or may be caused by the detection of failures of those technical devices which are under continuous supervision: function of the server and power lines.
The device to report alerts to the officer on duty is the so called alarm unit (ALU).
The alarm unit has 8 input channels. Once one of these 8 channels becomes inactive the device starts dialing a defined sequence of phone numbers which can be specified individually for all of the 8 channels. In any case the receiver (typically the staff member on duty) has to acknowledge the call. If the call is not acknowledged properly, the ALU activates the next phone number.
The normal way of operation is to inform the first staff member on duty via mobile phone. In the case that the first officer cannot be reached, the ALU tries the 2nd Operator. In the case that the call in not acknowledged properly, the ALU tries to call the central server room in Freiburg and finally the ALU tries to call the emergency phone on the measurement facility at the Schauinsland mountain.
The emegency phones in the central server room and on the Schauinland contains no electronics and drains power from the phone lines. This makes sure that they keep functional even in the case of a break down of the external power lines. Although all ISDN lines and the complete in-house phone system are connected to the UPS both emergency phones are operable even under worst case conditions.
Actually 3 different possible sources for alarms are supported.
Breakdown of the power lines (Not radiological alarm)
The uninterruptable power supply (UPS) is activated due to a failure of the power means. The server is protected against failures of the power means by an UPS combined with a diesel power generator. The UPS is continuously operational but has a battery capacity of only 2 hours to keep the server running. To allow the operation of the system for several days, a diesel power generator with an electric power of 5 kW is installed additionally to the UPS. The generator will be started automatically in case of a break-down of the power lines. Additionally an alert will be send to the personal on duty using one of the 8 alert channels of the alarm unit.
Server watch-dog (Not radiological alarm)
To notice server outrages a watchdog is connected to the server via serial line. Every 10 minutes the server sends a character sequence to this device. In the case that the sequence is missed the watch dog activates one channel of the alarm unit. Therefore any failure of the server (or the watchdog!) will cause an alarm.
[[Image:picture19.jpg|thumb|Figure 19 Watchdog of the Server
Radiological alarms
When a network internal alert is generated in the gamma dose rate network a radiological alarm will be generated. In this case the 3rd line of the ALU becomes activated using control signals of the serial line interface of the gamma dose rate network central server unit. A radiological alarm is always followed by the activation of an additional optical and acoustical alarm device. A network internal alert can only be generated at the central server, which is typically the server installed in Freiburg. In case of a failure of the server in Freiburg any server at the 5 locations in Berlin, Bonn, Rendsburg, Salzgitter or Neuherberg (Munich) can be used as central unit. Besides the function to generate the network internal alert, the central unit is used to validate all data before sending them to IMIS.
To have control over all 6 central server units and to allow to use any of the 6 servers as central unit, all 6 locations are identically equipped. This includes the server unit and the complete alarm system described. The server is a standard PC running at 1.8GHz. We replaced expensive workstations, since in case of a failure spare parts can now be bought in any shop whenever neccessary.
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