Waste Technology Section
Decommissioning
Facilitating the transfer of sustainable technologies for decommissioning of facilities
Responsible Officer : Michele LARAIA
Details of Technical Cooperation Projects:
GEO/3/002: Decommissioning of the IRT-M Research Reactor
The research nuclear reactor IRT-M of the Institute of Physics, Georgian Academy of Sciences with thermal power 2 MW (later on upgraded to 8 MW) was put in regular operation in 1959. IRT type nuclear reactors, designed in the former Soviet Union, pertain to the group of light water pool-type reactors in which the usual (light) water is used as a moderator of neutrons and as a coolant. In 1990 the Academy of Sciences of Georgia, taking into account the limited residual work resource of the reactor and expected large investments necessary for evaluation of seismic stability of buildings and the reactor, and the adverse reaction of the public after the Chernobyl tragedy, decided to withdraw finally the reactor of the Institute of Physics from operation and to decommission it. One should also consider that following the collapse of the former Soviet Union, Georgia was practically a non-nuclear country with modest chances of a nuclear revival.
The preferred strategy for decommissioning of research reactors is immediate dismantling after short term storage. For dismantling, the requirements are waste repositories, special cutting tools and equipment and facilities for conditioning and transporting highly radioactive waste. Many countries do not have these facilities or it would be uneconomic to invest in them. One of such countries is Georgia. In addition Georgia’s reactor had an ageing staff with many over 60 or even 70 and solutions leading to higher level of safety were urgent.
Quite naturally, given the circumstances, the most advantageous and reasonable strategy is conversion of the reactor into such a passive state which does not demand special control and supervision, and guarantees its safety even in extreme situations for long periods.
The preferred option which fully satisfies these requirements is immobilizing the most radioactive lower part of the reactor tank and inner cavities of horizontal experimental channels with concrete thereby encapsulating the radioactive waste. It should be mentioned that the option to encapsulate the lower section of the reactor requires a relatively small amount of concrete (20 m3) to be added to the existing huge reactor block which has a volume more than 300 m3. This will not increase difficulties of future dismantling, especially after long delay periods (more than 50 years) because due to radioactive decay, the residual activity will eventually only be from low concentrations of long-living radionuclides, such as 41Ca, 59Ni, 94Nb, 152Eu and 154Eu. One should note here that the Georgians do not view the reactor entombment as irreversible, but leave the option of full dismantling open.
The reactor was grouted in concrete and its final configuration reached in August 2002 under an IAEA TC project. A contract was recently stipulated between the IAEA and local counterparts to dismantle the peripheral systems of the reactor building. Eventually the only remaining radioactivity will be that confined within the concreted reactor monolith.
In 1999, the Latvian Government decided to decommission the research reactor near Riga at Salaspils. Since that time, the IAEA has provided active support for activities directly preparatory to decommissioning through a number of sequential TC projects.
LAT/4/006 (approved in 2003) was initiated with the main focus on minimizing the risk for radioactivity escape into the environment during decommissioning activities by monitoring the area for radiation and radioactive aerosols. In view of the forthcoming dismantling of the reactor’s core components and bioshield, the project also addressed other provisions and infrastructure required for the planning and subsequent implementation of those activities. This was intended to ensure radiation protection of the staff, the population and the environment during the subsequent critical phases of decommissioning (currently addressed by follow up project LAT/3/002).
The project focused on upgrading the radiation protection systems and radiological characterization. The Agency provided expert advice to the counterparts through the organization of ten expert missions in several areas relevant to the present phase of decommissioning including: air stack monitoring system implementation, drilling and sampling of the biological shield, underwater cutting of reactor components, BROKK equipment, waste management and disposal of materials, and radiological characterization. In addition, there were several missions fielded to monitor the project status and implementation, and a Latvian scientist undertook a scientific mission to exchange experiences on the characterization of reactor bioshield with colleagues in neighbouring Denmark.
During the project, IAEA provided substantial equipment and supported the upgrade of the cementation plant. A tritium monitor for the reactor hall and an air stack monitoring system and air sampling equipment and software were provided.
As a result of the project, protection of the environment and the public surrounding the Salaspils Research Institute has been strengthened, and the knowledge of the local counterpart team needed for the decommissioning has been enhanced.
RER/3/005: (Support in Planning the Decommissioning of Nuclear Power Plants and Research Reactors
In Central and Eastern Europe, common problems and issues in decommissioning include:
- Soviet designs;
- Common approach to operation;
- Similar inventory and waste management issues;
- Little or no experience in decommissioning;
- Limited resources;
- Legislation in review or development.
Since 2005 the Agency has provided technical assistance under RER/3/005 to countries with NPPs in Europe with the aim of assisting and facilitating the planning for decommissioning of these facilities in a way that complements other international support (e.g. through the European Commission-TACIS or PHARE and the European Bank for Reconstruction and Development projects). This assistance focuses on reviewing and advising on preliminary or final decommissioning plans (or parts of these plans) for specific NPPs in Armenia (Metsamor NPP), Bulgaria (Kozloduy NPP), Hungary (Paks NPP), Slovenia/Croatia (Krsko NPP), Russian Federation, and Ukraine (Chernobyl NPP). The continuation of the Technical Cooperation project RER/3/003 until 2009 has been recently approved by the IAEA Board of Governors. It is to be implemented as one TC project RER/3/005 together with the RER/9/058 TC project on assistance on decommissioning of research reactors in Europe.
The third project planning meeting was organized and hosted by EWN and Forschungszentrum Karlsruhe GmbH. The workshop was attended by eighteen participants from Armenia, Bulgaria, Croatia, Germany, Kazakhstan, Lithuania, Slovenia, Slovakia and Ukraine. It was held from 27 to 29 November 2006 at the Greifswald NPP. The meeting aimed; (i) to discuss project activities and achievements during 2006; (ii) identify the needs for Agency assistance in 2007-2009 and (iii) develop a work plan for the new RER/3/005 TC project activities related to the NPP decommissioning in 2007.
The two components of the Regional TC project, one for nuclear power plants, the other for research reactors, are structured in a similar way. A two-way mechanism was established whereby the participating institutions submit their decommissioning plans (or parts thereof) to the IAEA and expert missions are then organized to review those submissions and make recommendations.