Results of the first year of operation at Embalse Nuclear Power Station in Argentina

As a part of the International Remote Monitoring Project, during March 1995, a Remote Monitoring System (RMS) was installed at the Embalse Nuclear Power Station in Embalse, Argentina. This system monitors the status of four typical Candu spent fuel dry storage silos. The monitoring equipment for each silo consists of analog sensors for temperature and gamma radiation measurement; digital sensors for motion detection; and electronic fiber-optic seals. The monitoring system for each silo is connected to a wireless Authenticate Item Monitoring System (AIMS). This paper describes the operation of the RMS during the first year of the trial and presents the results of the signals reported by the system compared with the on site inspections conducted by the regulatory bodies, ABACC, IAEA, ENREN. As an additional security feature, each sensor periodically transmits authenticated State-of-Health (SOH) messages. This feature provides assurance that all sensors are operational and have not been tampered with. The details of the transmitted information and the incidents of loss of SOH, referred to as Missing SOH Event, and the possible causes which produced the MSOHE are described. The RMS at the embalse facility uses gamma radiation detectors in a strong radiation field of spent fuel dry storage silos. The detectors are Geiger Muller tubes and Silicon solid state diodes. The study of the thermal drift of electronics in GM detectors and the possible radiation damage in silicon detectors is shown. Since the initial installation, the system has been successfully interrogated from Buenos Aires and Albuquerque. The experience gained, and the small changes made in the hardware in order to improve the performance of the system is presented