Background

Beloyarsk NPP is situated in Sverdlovsk region of Russia, in the town of Zarechny, approximately 60 km east of Ekaterinburg and close to the Ural mountain range. It is one of the oldest commercial nuclear power plants in Russia and started operations in 1964. The first 2 units constructed at the site were AMB100 and AMB200 prototype units, which were forerunners of the RBMK reactors. These 2 units were shut down in 1981 and 1989 respectively. Unit 3 is a 600MWe sodium-cooled fast breeder reactor (FBR) known as BN-600, which started operation in 1980. In addition to the electrical production, the unit produces district heating for the town of Zarechny. Unit 3 is the only unit to have been involved in the Tacis On-Site Assistance. A fourth Unit, also a sodium-cooled FBR (BN-800) has been under construction since 1987, but has suffered many delays, mainly due to the financial difficulties in Russia in the 1990s.

In the frame of the TACIS 1997 programme it was proposed to replace the automatic fire detection system for the detection of fire in cable tunnels at the Unit 3. The existing fire detection/fighting system comprised one fire detection system and one fire extinguishing system allocated to each of the 41 cable tunnels at the unit. In total the system incorporated 1322 ionisation smoke detectors distributed between the 41 detection systems. Each detection system comprised two channels. When a detector on one channel is tripped, a warning alarm signal is sent to the control panel. A tripped detector on both channels results in actuation of the fire extinguishing system and actuation of the fire alarm.

The system suffered from the following deficiencies:

• poor reliability of the smoke detectors of the fire detection system,
• sensitivity of the detectors or the connecting cables to induction phenomena generated by the power cables located in the tunnels,
• a varying ambient temperature within the cable tunnels leading to condensation and streaming of water onto some of the smoke detectors, which were highly sensitive to high humidity and condensed moisture drops.

These deficiencies resulted in a large number of false alarms leading to safety concerns.

The difficulty of sourcing, on the Russian market, fire detectors of the required reliability, particularly considering the ambient conditions in the field, led to the decision to supply this equipment from the international market through the TACIS programme.

Objective

The objective of the project was the provision of new fire detection systems for installation in the cable tunnels of Unit 3. Due to limited budget the new fire detection systems would be provided for a total of 15 cable tunnels only. The fire detection systems to be supplied included:

• the fire detectors in sufficient quantity to equip 15 cable tunnels
• one control panel 
• the necessary cables for installation of the fire detectors and the control panel
• required mountings
• installation, testing and maintenance tools

The scope of work/supplies included the design, manufacture, factory acceptance testing, certification, delivery, site acceptance testing, supervision of installation and commissioning of the equipment. The scope of work also included the provision of spare parts, documentation, training of the End User personnel for the installation, operation and maintenance of the systems.

Results

The Call for Tender was launched in late 2000 and tenders were evaluated in March 2001. The contract was signed with Fortum Engineering on 8 May 2002. The equipment was delivered, installed and tested and the Provisional Acceptance Certificate was issued in May 2004. The Final Acceptance Certificate was issued in September 2006. Unfortunately, the system did not perform well and the supplied detectors were not able to withstand the declared ambient humidity in the tunnels. Moreover, the failures of the detectors were not diagnosed by the system and so their inoperability remained undetected and unknown to the operators until discovered during routine maintenance. The system was removed after two years of operation.