At the Vienna Chernobyl Conference in April 1996 Germany and France declared to support the international co-operation in view of a solution of the Chernobyl related issues.

In 1998 the multinational Sarcophagus Project was launched in the frame of this initiative.

The aim of the project is collection, analysis, selection and verification of all safety relevant data concerning building constructions, systems and equipment, radiological situation, nuclear fuel, radioactive waste and environmental impact in a comprehensive data base.

ArcView GIS, spatial analyst and 3D analyst serve as a navigation system to retrieve the information from the data base using different cross sections of the Sarcophagus.
 

After the declaration of Germany and France at the Vienna Chernobyl Conference in April 1996 to support the international co-operation of institutions of the Ukraine, Belarus and Russia in view of a solution of the Chernobyl related issues, three project were identified, i.e. the safety state of the Chernobyl Sarcophagus, the radioecological consequences due to the radioactive contaminated areas and the health consequences of the liquidators and the population in Ukraine, Belarus and Russia after the Chernobyl accident. The projects are funded by the governments and by the electricity utilities of Germany and France, respectively.

In this paper the Sarcophagus project will be presented.

Fourteen years after the accident of unit 4 of the Chernobyl NPP the Sarcophagus still remains one of the most dangerous nuclear facilities in the world. The ruin of the destroyed unit 4 and its surrounding Sarcophagus together are termed object Shelter.

The Sarcophagus was erected in a relatively short time period of several months on the basements of old structures of unknown stability of the former unit 4. Inside the Shelter remained about 96 % of the irradiated nuclear fuel inventory of the reactor of unit 4 before the accident, i.e. 180 t of Uranium of total radioactivity 7 x 10¹⁷ Bq. The radioactive releases to the industrial site of 500 m radius around the Chernobyl NPP during the first ten days after the accident were estimated to amount 0,5 - 1,0 % of the fuel inventory.

The spent fuel inside the Shelter and the radioactive contamination at the industrial site have an essential impact on all human activities concerned with investigation work, maintenance and stabilisation measures which are presently under progress e.g. in the framework of the Shelter Implementation Plan because of the radiation exposure.

For planning of any actions towards a stabilisation of the unstable building constructions of the Shelter and of measures to retain the radioactive materials inside the Sarcophagus a unified and comprehensive data base of all safety relevant technical data describing the present safety state of the Shelter is required.

Hence, the main aim of the Shelter project is the collection, analysis and selection as well as verification of all existing safety relevant data of the Shelter and the creation of an appropriate data base.

The data base will be useful for different applications, e.g. for performing stabilisation measures in the framework of the Shelter Implementation Plan (SIP) or for the corresponding licensing procedure of the national authority of Ukraine.

The project management is carried out by GRS and IPSN on behalf of the German and French governments and utilities, respectively. The local project co-ordination in Ukraine is carried out by the Chornobyl Centre which will also be the beneficiary of the work. The work is being performed by local contractors. The progress of work is frequently estimated and ruled by the project review group from the above mentioned organisations together with the contractors.

During a preparation phase after the declaration of the initiative in 1996 the main tasks of the project were identified and the terms of references including detailed technical specifications of the work were elaborated. These main tasks are Building Constructions, Systems and Equipment, Radiological Situation, Fuel Containing Materials and Radioactive Waste and Environmental Impact.

In May 1998 the sub-projects with the local contractors were launched.

The project duration is three years, the total budget amounts to 4 Million Deutsche Mark.

The technical organisation of the project is the following. For each technical task in a first step the main sources of information, i.e. technical documents, publications etc., were identified and described in a bibliography. In the next steps the technical quantities of interest are extracted from theses documents and input into a data base. The input of data is performed by the contractors using especially designed interfaces, which address the kind and the total amount of data for the given task. The development of interfaces, the structure and the configuration of the data base as well as the data integration is subject to a separate contract.

Besides internal quality control of the technical data, performed by each of the contractors, additionally an independent expert team of Atomaudit (AA), Kiev, Ukraine, is involved in external quality control of the work. The configuration of the data base and data integration is also subject to independent control by a GRS supervisor.

The contents of this work is the description of the building constructions before and after the accident. To the parameters considered in this task belong the geometrical dimensions of the rooms, of the walls and of special objects, their properties, e.g. quality of concrete and other building materials, load bearing capacity, order of destruction of walls and other construction elements, newly filled concrete and accessibility of rooms, etc. These data serve as a basis for new projects to reinforce the Sarcophagus.

This work is being carried out by the State Research Institute of Building Constructions (NDIBC), Kiev, Ukraine.

This work contains the description of all systems and equipment installed in the Shelter before and after the accident, i.e. electricity supply systems, water supply and drains, ventilation system, measuring and monitoring systems, etc.

This work is being carried out by the NDIBC in co-operation with the Chernobyl Nuclear Power Plant, Object "Shelter" (CNPPOS), Chernobyl, Ukraine.

The scope of this work is the description of the radiological situation inside the Shelter, i.e. the dose rates of the radiation fields and the radioactive contamination in the rooms of the Shelter. In order to estimate the radiation exposure in advance when planning work to be carried out by the personnel these data are of special interest.

This work is being carried out by the Russian Research Center “Kurchatov Institute” (RRCKI), Moscow, Russia, in co-operation with the CNPPOS.

This work deals with the description of the influence of the accident to the Shelter site, i.e. the radiation situation above the ground, the contamination and the behaviour of the groundwater, the airborne effluents from the Sarcophagus and the radioactive air contamination at the Shelter site. These data are also of special interest e.g. for planning preparation work near the Shelter for stabilisation measures etc.

This work is being carried out by the Interdisciplinary Scientific and Technical Centre "Shelter" (ISTC), Chernobyl City, Ukraine.

The scope of this work is the development of the data base structure, including the bibliography and the contributions of the different technical tasks, described above, as well as the development of a proper technique to retrieve the required information by key words as well as by the help of the optical navigation system ArcView GIS.

The data are organised and structured according to the main topics of contents described above in a data base under Microsoft Access. The technical topics are subdivided into objects, e.g. rooms, construction elements, systems, equipment elements, measuring devices, fuel assemblies and fuel debris, pieces of fuel lave, etc., which are generally connected with the corresponding 3D co-ordinates (axis, row and height level). The 3D co-ordinates of the Shelter are prolonged towards the industrial site allowing the description of the environmental impact to the Shelter site in a uniform co-ordinate system.

The states of the objects are described by a text abstract and by the technical parameters with regard to the terms of references of the contracts. Auxiliary data, e.g. graphs, construction drawings, photos, original and animation videos, are also linked with the technical data to facilitate a better understanding.

The main technical quantities contained in the data base are always linked with the corresponding main sources of information described in the bibliography. A hint to the responsible contractor validating the technical data is also always given.

All data are presented bilingual in English and in Russian using a switch button.

All information available in the data base can generally be retrieved by an optical navigation system based on ArcView GIS 3.2.

For each height level of the Shelter a 2D cross section containing the main objects, e.g. walls, doors, rooms, stairs, main constructions elements, newly filled concrete, fuel containing materials, main systems and equipment, etc. was elaborated.

Analogously, for the Shelter site a 2D cross sections containing data about the elevation levels of the territory, the radiation fields at height levels from 1 m up to 70 m above ground as well as about the groundwater table and the radioactive contamination of the groundwater was designed.

From the ArcView platform via the information button a direct entry to the access data base is released and all primary technical and auxiliary data can be found. Using the animation button additional information from original and animation video films can be started.

Selected images can be viewed by means of the 3D analyst. This is of special interest for the whole Shelter and the industrial site as well as for different objects belonging to more than one height level. For such kind of objects also a direct access from the 3D images to the data base was realised.

For practical purposes and different applications a processing of the primary data contained in the data base is of interest. The scope of the Sarcophagus project of the German-French Initiative does in general not include processing of primary data and production of secondary data for special practical applications by means of models etc. However, some simple applications based on a straight algorithm, i. e. prognosis of dose rate in the future based on the radioactive decay of Cs 137 etc., have been foreseen. Other applications available are facilitated by the spatial analyst.

One example is the calculation of the dose uptake of personnel due to radiation exposure when walking over contaminated areas at the Shelter site or in rooms inside the Sarcophagus in high radiation fields. Indicating a walk route and a constant moving velocity of the personnel, the spatial analyst calculates the accumulated dose along the pathway.