NPP decommissioning is the last stage of power plant existence after it was designed, constructed, started to operate and was in operation. The ultimate goal of decommissioning is to achieve the condition when the territory is out of control of national supervisory authorities and may be used for other purposes.
Requirements for the Decommissioning of Nuclear Facilities (P-2009-02) are the main legislative document whereby INPP plans and carries out the decommissioning. They were approved by the head of State Nuclear Power safety Inspectorate (VATESI) in 2009.
Ignalina NPP decommissioning project includes decommissioning of Unit 1 and 2 and auxiliary facilities.
According to the EU's economic support program's PHARE project in 1999 preliminary INPP Decommissioning Plan was developed. Three possible options for decommissioning strategies were considered there - immediate dismantling, deferred dismantling and safe conservation and entombment.
According to the International Atomic Energy Agency's (IAEA) project "Support for the Decommissioning of Ignalina NPP Unit 1" (LIT/4/002) in February 2001, IAEA experts prepared a report where the immediate dismantling option was offered as an Ignalina NPP decommissioning strategy - the way when the equipment is dismantled practically immediately after the closure of reactor's operation.
On 26 November 2002, Lithuanian Government passed a resolution to the effect that the Ignalina NPP Unit 1 is to be decommissioned through immediate dismantling in order to avoid serious social, economic, financial and environmental consequences.
The choice of method of decommissioning was influenced by various factors: economic, social, safety aspects and decommissioning work experience at other nuclear power plants.
Representatives of Ignalina NPP were also in favor of immediate dismantling because in this case prerequisites would be created for improving employment rate - experienced professionals would be invoked. One of the Ignalina NPP decommissioning priorities is in-house approach - to perform as many works as possible with INPP personnel help.
Final Decommissioning Plan
The Final Decommissioning Plan (FDP) was prepared in 2001-2004 by the INPP and approved in 2005 by the order of the Minister of Economy of the Republic of Lithuania. Ministry of Economy of the Republic of Lithuania coordinated INPP decommissioning process by 2009. At the moment, Ministry of Energy of the Republic of Lithuania performs this function. On 25th August 2014, Minister of Energy of the Republic of Lithuania approved revision 7 of FDP covering amendments made according to the experience gained by INPP.
FDP covers the whole INPP decommissioning period (two Units, auxiliary equipment, interim spent fuel and radioactive waste storage facilities). Decommissioning activities and projects are planned on the basis of the strategy that is submitted in this plan (all decommissioning activities are grouped into decommissioning projects in FDP), principles, methods, techniques and overall plan-timetable are described that are required for ensuring safe, ecological and economic INPP decommissioning from radiation safety point of view.
It is expected to achieve the "brown field" end-stage by 2038 - to arrange power plant's environment in a proper way so that it would be possible to rehabilitate its territory and develop economic activity preserving buildings and infrastructure that can be used.
Stages of Ignalina NPP decommissioning
The initial stage. Nuclear power plant is suspended permanently. It is cleaned and decontaminated using available equipment. Spent nuclear fuel and accumulated radioactive waste is transferred to interim storage or entombment. Low-radioactivity units can be removed.
Dismantling. This phase should start after the first stage immediately. Radioactive equipment and inner layer of radioactive buildings are removed during the dismantling. This is the most difficult phase from the technical point of view.
Demolition of buildings. During this stage buildings are to be demolished or left for further use. They are to be demolished in the same way as other industrial facilities except that thorough checks are to be conducted for the trace amounts of radioactivity in the debris.