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Deactivation of NPP Elements

#0943


A Device for Deactivation of NPP Constructional Elements' Surfaces Using Gas-Abrasive Method

Tech Area / Field

  • FIR-DEC/Decommissioning/Fission Reactors

Статус
3 Approved without Funding

Дата регистрации
06.04.1997

Ведущий институт
Joint Institute for High Temperatures RAS, Russia, Moscow

Поддержка институтов

  • VNIIEF, Russia, N. Novgorod reg., Sarov\nNIIIT (Pulse Techniques), Russia, Moscow\nBeloyarsk NPP, Russia, Sverdlovsk reg., Zarechny\nMIFI, Russia, Moscow\nVNIPI Promtechnology, Russia, Moscow

Краткое описание проекта

The Project is aimed at making of a device for de-activation of NPP constructional concrete elements' surfaces using complex thermo-gas-abrasive method. The Project is based on results of scientific and technological investigations on gas- and steam-abrasive cutters and destruction of heat-protecting coatings. These investigations made earlier witness the possibility of removal of surface layers of concrete constructions in atomic power technology and industry polluted by radionuclides.

A principal feature of the proposed method is the combined influence on hard materials' surfaces being destroyed. At the first stage, alternating thermal influence is performed which results in thermal shock or thermal loss of strength. Depending on the amplitude-frequency parameters of thermal influence, the concrete's loss of strength may take place from several times to ten times or more. In this case gas-abrasive jet influence is not necessary. Just mechanical influence of a gas jet is sufficient for separation of a surface layer from the bulk of concrete. Depending of physico-chemical properties of concrete, the phenomenon of "steam explosion" may be realized in presence of a thermal disturbance. Here full separation of the surface layer of the concrete bulk occurs. By the regulation of the thermal influence parameters one can control the thickness of the separated layer. In both cases, use of supersonic heterogeneous flow is expedient only for dressing surfaces of concrete constructions or for de-activation of such elements on which it is difficult to influence thermally (corner elements of concrete constructions, joints of walls with ceilings or floors, technological grooves, deep crevices etc.).

While taking measures for de-activation and in many other practically important cases, the proposed method may be realized for cropping (cutting of foundations, columns, spans etc.). Preliminary thermal influence on concrete with subsequent influence of a supersonic heterogeneous flow helps to increase considerably the concrete removal effectiveness and at least by 1.5 to 2 times decrease the cost of work when compared with the best modern technologies.

Combined gas- or steam-abrasive effect and pulsed thermal effect on de-activated surface allows to remove layers of polluted substance with depths up to 20 mm and more if necessary. The depth of concrete to be removed is determined by extent and depth of pollution.

То determine radioactive contamination parameters, development of technologies and apparate means providing monitoring of de-aptivation processes is foreseen.

The proposed method of de-activation excludes essential shortcomings intrinsic for other ways of effect on a surface, such as using an impact device, highly intensive thermal processing or explosion method (uncontrolled destruction of the processed surface, intensive degassing).

Rather substantial feature for wide introduction of the proposed method is that it uses only technologies and aggregates which are widely used in the facilities of NPP and nuclear industry. In this sense there should be no psychological barrier for this method's application as no ultra-modern (exotic) equipment is used in it, that is what usually sustains application of the newest technologies. The proposed method uses only new combinations and subsequences of realization of working processes that are widely used in other technologies of nuclear power technology and industry.

The distinctive feature of scientific and technological approaches forming the Project's methodology is the unification of achievements in the fields of thermomechanics of heterogeneous flows interacting with solid bodies with radiation control of the target and the products of its destruction by low-background dosimetry and gamma-spectrometry.

Technical approach in solution of the Project's main problems is the following:


- determination of effectiveness of various regimes of thermal effect on a surface;
- optimization of regime parameters for combined gas-abrasive and thermal effect;
- study and experimental finishing of speeding-up regimes of hard particles under heterogeneous flow;
- study of regime and constructional parameters that determine maximal speeding up of abrasive particles;
- making of a working experimental pilot device for de-activation and its tests;
- development of control methods and systems for radioactive pollution of surfaces before and after their processing;
- development of methodology and technology of burial of grained radioactive waste.

As a result, a working experimental pilot device for combined thermal and gas-abrasive (gas) effect on constructions' surfaces will be made that will allow removing polluted substance layer after layer. Simultaneously monitoring methods of de-activation processes and method of burial of radioactive waste, realized in the system of radioactive contamination control, will be developed.

Probation and testing of an operating pilot device is planned in the Beloyarsk NPP. The results of tests will be delivered to the wide scientific and technological community and will permit subsequently to go to the creation of a full-scale experimental sample of an automated device for de-activation of surfaces of elements of NPP constructions by the complex thermo-gas-abrasive method.

Project's performers would greatly appreciate the interest for and consideration of working materials and referring of the Project.

Cooperation with interested partners can be carried out in the following main directions:


- scientific and technological information exchange, carrying out of consultation meetings, workshops;
- determination of actuality and novelty of the proposed technical solutions and expansion of the Project's results to other neighboring fields in the international community;
- rendering information help in finding the most appropriate companies making special materials and equipment for their possible use in carrying out the Project;
- attraction of companies having interest in carrying out the Project and its further realization.

Please direct your reviews of the Project by mail to KTC's address: ISTC Executive Director, P.O.Box 25, Moscow 115516, fax: +7 (095) 321-4744, +7 (095) 321-4992


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