Modernization is the basis of the safety and prolonged lives of the units of Kursk NPP

In 1990 the State Atomic Energy Inspection imposed capacity restriction on the 1st and 2nd units of Kursk NPP (70%). Since 1993 the plant has been constantly modernizing its units.

Modernization of the 1st unit

The first stage of the project – Apr 1994-Dec 1997:

Fuel channels replaced; graphite moderator restored; screw locks installed.
Cooling system modernized:
two additional emergency pumps launched;
distributing headers equipped with check valves;
nozzles upgraded.
Separator drums modernized.
Steam-water mixture discharge system modernized.
Circulation loops connected to technical water and fire security systems for emergency water supply.
Control system modernized:
hafnate detectors installed.
Emergency system modernized.
Diesel power plant modernized.
High-speed feed system modernized.
The 1st unit began using to uranium-erbium fuel.
Coolant leak control system launched.

The second stage of the project – Oct 2003-June 2004:

1,065 fuel channels replaced
SKALA-MICRO, uninterrupted electricity supply and some other systems launched;
PRISMA-M capacity distribution control program introduced;
Roof of the central hall reinforced;
Radiation control system modernized;
Emergency control board launched;
Physical protection and fire security system upgraded;
riticality control system launched;
Safety analysis conducted.

The 2nd unit was restarted in June 2004.

Since Nov 2004 the 1st and 2nd units of Kursk NPP has been operating at nominal capacity.

The neutron-physical parameters of the active zone have been improved due to new type of nuclear fuel and cluster control systems. The analysis has shown that after modernization the reactors are:

safe and protected;
have negative reactivity temperature coefficient and negative high reactivity capacity coefficient;
desiccation effect has been reduced to ~1β.

The assembly channels and fuel elements have reserve capacity for normal operation. The emergency and capacity reduction systems are independent and keep the reaction in sub-critical state under both normal and emergency conditions.

The risk factor for the 1st and 2nd units has been reduced from 6,17x10 -5 to 9,34x10 -6 per reactor a year. This is half of the standard set by IAEA Safety Series No. 75-INSAG-3, Vienna, 1988 for old reactors.

International safety analysis inspection of the 1st unit of Kursk NPP

A large-scale safety analysis was carried out at the 1st unit of Kursk NPP in Oct 2002-Apr 2004 under an agreement between the Government of the Russian Federation and the European Bank for Reconstruction and Development. It was the first safety analysis at an NPP with RBMK.

70 foreign experts were involved in this project: from RISKAUDIT IRSN/GRS International, AECL (Canada), Batelle PNNL (US), GRS (Germany), IRSN (France), NNC Limited (UK), NGR (Netherlands), SERGO (UK), Scientech Inc. (US). All of them were official nominated by EBRD. The Russian experts represented Nuclear Safety Institute, Institute of Physic and Power Engineering, LNPP.

36 working meetings were conducted during the project. Foreign experts paid three visits to Kursk NPP. The experts inspected the safety systems of the plant and met with the local personnel. They could see with their own eyes the results of the plant’s modernization and safety enhancement measures.

Their findings and recommendations were summarized in a report describing the state of the 1st unit of Kursk NPP after modernization.

The key conclusions of the experts were as follows:

The safety of the 1st unit of Kursk NPP has been significantly enhanced as a result of the modernization of the emergency cooling, control, safety and other significant systems.
The significant deviations from the existing Russian standards and IAEA recommendations concerning RBMK safety have been removed.

In May 2004 the Senior Review Group of EBRD approved the report thereby confirming the fulfillment of Russia’s commitment to improve the safety of NPPs with first-generation RBMK reactors.

The operating organization approved the results of the analysis and pointed out that the foreign experts had accepted Russia’s approaches to RBML safety enhancement and further operation.

Key directions for further enhancement of the safety of Kursk NPP

Kursk NPP is planning to modernize its 3rd and 4th units and to carry out the following measures:

To improve the content of the active zone (2.8%-enriched uranium-erbium fuel, cluster control systems) with a view to enhance the reactor’s self-protection capacity. The 3rd and 4th units used uranium-erbium fuel for the first time in Jan 2005. This fuel (2.8-enriched uranium-235 with 0.6% erbium oxide content) has been tested and licensed by relevant authorities. The new fuel is quite good and is being successfully used by the plant. The cluster control systems have helped to reduce the positive radioactivity effect resulting from desiccation.
To introduce new computing programs;
To modernize emergency response system;
To enhance the safety of the essential systems;
To introduce control system;
To introduce criticality analysis system at the 3rd and 4th units.
To improve personnel training and to enhance safety culture.
To work out new measures on the basis of analysis of the previous ones and comparison with the standard requirements;
To continue deep safety analysis.