Introduction

The nuclear power plant Nord near the town of Greifswald was built using the Soviet design on the coast of the Baltic Sea. The first power unit with the first-generation VVER-440/230 reactor was put into operation in 1973. Later three more power units were built with reactors of the same type.
Construction of four more second-generation power units with VVER-440/213 reactors was started. But only one of them was put into operation in 1989, it was the fifth power unit of NPP Nord.

Reasons of NPP closure

In 1990, after the East and West Germany was united, secret reports on the safety of the first four Nord power units were published. They contained information about the unacceptably high risk of further operation of the first four power units; main problems - high degree of neutron embitterment and corrosion pits of reactor vessels, design drawbacks of steam generators, erroneous orientation of turbines versus reactor and a number of others.
Modernization of the first four power units was estimated as economically unfeasible.
The fifth power unit with VVER-440/213 reactor could be improved and upgraded to the safety standards of West Germany, because it belonged to the latest generation of this reactor type. But about 50.000 changes was made in the design documentation of this reactor during its construction. At this there was not a single document describing those changes. It seriously complicated the job on safety upgrade of the fifth power unit. As a result, the SIEMENS company, West German NPP developer, refused to take the responsibility for the power unit modernization in accordance with accepted standards.

Decision about decommissioning

In view of the above-mentioned in 1990 the government of unified Germany took a political decision about the shutdown of all operating power units. The construction of remaining   three power units, which were in different degrees of preparedness, was suspended.
Absence of previously developed decommissioning programs resulted in high decommissioning
costs at the first stage (1.3 bln. Euro from 1990 till 1995.). Provisions were made to ensure public and technological safety; the development of decommissioning strategy, technological procedures and legislative norms was accelerated.

Public control of decommissioning

Federal authorities founded the Public Council for the monitoring of NPP decommissioning.
It included the representatives of federal, regional, municipal authorities, experts, representatives of NPP workers, political parties and NGOs. The Council members (16 persons) work on a voluntary basis (no salaries paid) and its activities are regulated by the Council Charter. Budget of the Council is about 250 th. euro/year. It covers the transport expenses of the Council members to take part in its work and organization of independent examinations and surveys.
Council activities are open for mass media. Such approach relieved social tension in the beginning of decommissioning work.

Decommissioning scenario justification

After the analysis of possible decommissioning scenarios (delayed for decades or immediate decommissioning) a concept of immediate decommissioning was chosen. This decision enabled to employ about one third of 5564 (1990) NPP workers for decommissioning operations. This prevented the social crisis of a simultaneous loss of jobs by thousands  people, and the decades of waiting period until the short-lived radionuclides decay was finished..
Another argument for the immediate decommissioning is the possibility to use the handling and lifting equipment of operating power units. Such equipment loses its operational qualities after a long period of waiting, if the delayed decommissioning strategy is chosen. On the other hand, such decision required the development of hightech dismantling methods for radioactive equipment. The decisions gave an impetus for developing such technologies, which can be useful for other NPPs. The new dismantling technologies ensured personnel dose rates lower than NPP operators .

Decommissioning

The program of NPP personnel adaptation was prepared in order to keep qualified
specialists at the plant, and help to most socially vulnerable. Retraining courses were started.
In 1995 after the legal and regulatory base was finalized, a permit for staged power unit dismantling was received. Public company Energiewerke Nord GMBh was entrusted with the management of this process.
An intermediate RW and SNF storage facility was built on the plant territory; advanced
methods of cutting radioactive equipment were introduced. After SNF was cooled in the reactor room storage pools it was transferred to Kastor containers and transported to the intermediate storage.
Halls and workshops freed after equipment dismantling were offered to new businesses.
At present the territory of former NPP hosts a technopark, which uses some of old  infrastructure. The discharge channel connected to the Baltic Sea, which had been used for cooling turbine condensers, was converted into a sea port. It is used by the new business, which is developed on the territory of former NPP shops. For example, the 1200 m-long turbine hall is used for  the production of pontoons, which can be shipped via the port in the former discharge channel.
In the period of 1990 - 2035 about 3.2bln. euro will be spent on the decommissioning of 5 operated VVER-440 power units. By this time all reactor buildings, other equipment, parts of other structures will be dismantled, cut and transferred to the intermediate storage.
The issue of final SNF repository or longterm monitored storage has not been decided about yet; it will need additional budgeting. Replacing sources of power The power lost after NPP Nord (Greifswald) closure is compensated in accordance with the strategy of priority development of renewable energy (wind energy) and import of gas from Russia via the Baltic ”Nordstream” gas pipeline.
The gas line will come to the surface from the Baltic Sea bottom near the decommissioned NPP. A gas power plant is planned on the site, which will have the steam-gas cycle and efficiency coefficient of approx. 50%.
Evaluation of results German experience shows that the use of NPP infrastructure at its decommissioning can reduce the cost of dismantling. The dismantling of contaminated equipment is possible without waiting for 50-70 years until most radioisotopes decay. The dose rate of personnel engaged in decommissioning is lower than during the plant operation.
The employment of plant personnel for decommissioning operations mitigates the problem of unemployment, which is better in comparison with the delayed decommissioning
option - in the latter case nearly all workforce employed a the plant lose their jobs. There is no need in extensive decommissioning training, because the personnel knows the plant well. This is also the factor of cost reduction in comparison with the decommissioning delayed for several decades, in the latter case full-scale training is necessary.
The NPP Nord (Greifswald) decommissioning experience is the world-largest project of this kind. The acquired technological experience is in demand in other countries.