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Dangerous Objects of «Kurchatov Institute»

#3232


Radiation Investigation of Nuclear Dangerous and Radiation Dangerous Objects of the Russian Research Center «Kurchatov Institute» for Scheduling of Works on Their Decommissioning

Tech Area / Field

  • FIR-DEC/Decommissioning/Fission Reactors

Статус
3 Approved without Funding

Дата регистрации
31.03.2005

Ведущий институт
Kurchatov Research Center, Russia, Moscow

Соавторы

  • RWE NUKEM GmbH, Germany, Alzenau\nVanderbilt University, USA, TN, Nashville

Краткое описание проекта

The purpose of the project: Deriving of input information necessary for the scheduling of works on decommissioning of nuclear-hazardous and radiation-dangerous objects of the RRC «Kurchatov institute», including:
  • values of the dose fields parameters in the compartments occupied by reactor installations;
  • rate of contamination of modules and machinery of the equipment of reactor installations;
  • rate of contamination of technological rooms of reactor installations;
  • data on component structure of radionuclides (b, a-radiating nuclides, transuranic elements) on the contaminated surfaces of equipment and in air;
  • the quantitative and qualitative characteristics of the composition of the radioactive waste having been formed while research nuclear installations were being dismantled.

For accomplishment of the task in view, the Project stipulates fulfillment of radiation investigation of nuclear-hazardous and radiation-dangerous objects in the RRC «Kurchatov Institute». These objects includes the reactors of MR, RFT, "Gamma", the "Gasworks" object (VVR-2), testbed complexes "R" ("Romashka"), "Yenisei".

The radiation investigation of the research nuclear installations (RNI) stipulated by the Project will comprise inspection of the following:

  • the technologic equipment of RNI;
  • internals of reactors;
  • technological compartments of the RNI;
  • the equipment of RNI, which were disassembled earlier.

The Project stipulates usage of calculated-analytical method for obtaining a part of the information, because in some cases the direct method of measurements is unacceptable for some reasons (unfavorable radiation situation, inaccessibility of equipment, impossibility of sampling, etc.).

Finally, the complex of works under the Project should include the following list of works:

  • Collecting, generalization and analyzing of the available documentary information.
  • Carrying out of the radiation inspection of reactor installations.
  • Calculated assessment of component structure of radionuclides in the deposits on surfaces of pipelines and equipment and of the induced activity of radionuclides in the constructional materials, which were in the nuclear core of reactor.
  • Assessment of a rate of contamination of surfaces of equipment by radionuclides; assessment of a rate of induced activity in constructional materials.
  • Calculation of volumetric activity of radioactive waste (RW).
  • Definition of volumes of RW and classification of the waste by categories.

Works under the Project will be executed by employees of the Centre, the most of which are working (or worked) at the objects of the Institute for Nuclear Reactors (INR) of the Center (at the MR, RFT, "Gamma", the object of "Gasworks" (VVR-2), at the test-bed complexes "R" ("Romashka"), "Yenisei“). These employees are possessing wide experience of practical activities related to exploitation of RNI, which is expected to be very useful when working under the Project.

45 persons are participants of the Project. There are one academician, 3 doctors of sciences, 7 candidates of sciences among them; 27 participants of the Project were engaged in a weapon-grade activity earlier.

The results, which can be obtained while fulfilling the Project and the further works on decommissioning of radiation-dangerous objects of the RRC KI, can be used for the accomplishment of similar tasks at other objects in the territory of the Russian Federation and countries of the CIS. Supposed results of the Project, according as they are being obtained, will be used in the projects of BNG, Tacis called above and in projects of RosAtom.

From the point of view of the methodology of the solving of problem, which is being set by the Project, works can be pided into two parts. Works on immediate radiation inspection of RNI can be related to the first part. These works, when they are appropriately equipped with the relevant instrumentware, are ordinary enough and do not require special methodological ensuring. When fulfilling these works, some difficulties are expected to be caused by the complicated radiation conditions in some sites of RNI of the Center.

The works, which will demand usage of calculated-analytical methods, should be related to the second category. It concerns, first of all, the works on the quantitative assessment of composition of RW, which were being formed at dismantling of RNIs.

From the point of view of formation of a source of rdioactivity, elements of constructions of reactor installations can be assorted into two groups: - the elements, which were inside the nuclear core and the baffle, while the reactor was in operation, and the elements, which were outside of these clusters.

For the equipment, which was outside of the nuclear core, the main source of radioactivity is contamination of surfaces by fission products, corrosion products and fuel. For the equipment, which was inside the nuclear core and baffle during exploitation of the reactor, the induced activity of constructional materials and admixtures in them is a main source of radioactivity, in addition to contamination of surfaces by radionuclides.

Because two essentially different mechanisms of formation of sources of contamination of clusters and equipment of reactor installations are being present, different methods of assessment should be used:

  • The induced activity of the clusters and equipment, which were exposed to neutron flux, can be assessed reasoning from the parameters of design elements, value of flux density of thermal and fast neutrons, duration of irradiation and the time of cooling them after termination of irradiation.
  • Rate of contamination of surfaces of modules and equipment by radionuclides of fission products can be assessed reasoning from results of dosimetric surveying of dismantled equipment and from calculated values of possible component structure of radionuclides. In this case, assessment of contamination of parts and modules of equipment of RNI requires availability of the data of radiation surveying, and usage of computational methods for ascertaining intensity of gamma radiation from volumetric sources.


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