Nuclear Related Papers

I

(This work is carried out under financial support of the United States of America in the frame of the Science and Technology Center in Ukraine)

The problems of resources saving and prevention of harmful contaminant ejection into the environment, that appear during the exploitation of important units of NPP constructions, are especially actual today. The important problem is a development of diagnostic equipment and methods directed to the detection of parts (in important NPP constructions) that are the stress-concentrators, the detection of fatigue strain and pre-destruction zones, gas and vapour flows. It is most advisable to carry out these measurements using the equipment based on the new methods of holography and interferometry. Interferometric and holographic methods are the most sensitive to the changes of the surface stress condition. They allow to visualise the deformation, fatigue and pre-destruction zones, to carry out the integral observations and, at the same time, to detect the stress-concentrators and the changes of the condition of observing surface. Thus, holographic methods will expand the existing ones and will enlarge the possibilities of diagnostics.

The problem is that the nuclear power plant is a zone with hard conditions of equipment exploitation (high radiation, vibrations, unstable temperature mode). To provide the effective diagnostics, the measuring devices must be jamming-proofed, remote controlled and must meet the requirements of reliability, high sensitivity and real time capacity for work.

Thus, the main purpose of the work is a development of holographic and interferometric equipment for contactless non-destructive control of stress-strained condition of important modules and units in nuclear power plants.

The wide known method of the two-exposured holographic interferometry is taken to the base of methodological conception of creating interferometric and holographic equipment. This method allows to obtain the integral submission regarding the stress-strained condition of the object and the surface and undersurface defects. The use of holographic interferometer for diagnostics of NPP objects requires the significant changes in conventional measuring methods and chime of the interferometer.

For holographic study of vibrating objects (that take place on NPP) we propose to use pulse laser holography with adaptive methods of hologram detection. To ensure adaptive hologram recording for unstable objects, it is provided that parallel to the channel of holographic recording, the channel of contactless measurement of vibration parameters operates. We use laser Doppler vibrometer with fiber probe to obtain the information about vibration. Laser Doppler vibration meter is also the source of additional independent information regarding construction state.

To ensure mobility, remote control and possibility of diagnostics of zones with difficult access, we propose to use the special light guide channels for transmission of laser radiation. It is supposed that the increase of jamming-proofing of light guide channels will be reached using the correlation methods of light front correction

Holographic image recording is carried out as using thermoplastic camera (laboratory testing) as using CCD camera (standard mode). The use of holographic interferometer for diagnostics of NPP objects requires the significant changes in conventional measuring methods.

At the this moment full concept of the created holographic interferometry diagnostic complex has been developed. Test experiments of all parts of this equipment have been carried out. Anticipating characteristics of the diagnostic complex are presented for discussing.