US Dept. of Energy Office of International
Nuclear Safety and Cooperation 1000 Independence Ave S.W.
Washington, DC 20585 (301) 903-0234 |
Each RBMK
reactor relies on approximately 2,000 high-speed pumps and ventilators to
operate safely. Many of these pumps supply cooling water to keep reactor
fuel in a safe temperature range. If normal cooling water were lost
suddenly, the reactor core could become dangerously hot, potentially
cracking or melting the covering around the fuel and releasing highly
radioactive materials. To minimize this possibility, a backup system of
emergency pumps is kept on constant stand-by, ready to flood the fuel core
with water until the reactor can be shut down safely and the problem
corrected. High-speed, rotating pump parts must be kept in
precise alignment so that they perform as intended in normal and emergency
situations. The slightest misalignment or imbalance of rotating pump
machinery can lead to bearing and seal failure, resulting in degradation
of equipment performance and premature failure. Misaligned pump shafts
cause about 70 percent of pump failures in operating nuclear reactors in
the United States. It is estimated that a similar figure applies in the
former Soviet Union. Through a
program implemented by the U.S. Department of Energy, state-of-the-art
vibration monitoring and shaft alignment systems are being provided to all
RBMK reactor facilities: Chornobyl in Ukraine; Ignalina in Lithuania; and
Leningrad, Smolensk and Kursk in Russia. The systems, significantly better
than equipment currently in use, enable maintenance staff to detect,
diagnose and correct misalignment and imbalance in rotating machinery.
The vibration monitoring system uses a hand-held computer that can
upload data from a rotating machine. The system has superior computational
ability that requires less operator training and enables operators to take
measurements with greater accuracy than previously possible. This
significantly reduces the possibilities of misdiagnosis and incorrect
repair of the operating equipment. Equipment also is being
provided for precise shaft alignments, including computerized laser
alignment tools. When mounted on the shaft of machines, the laser can
detect a misalignment with high precision in a matter of
seconds. The compact computer performs calculations, provides digital
read-outs, and advises the operator on the adjustments necessary to
properly align the equipment being tested. The information is recorded and
stored in the analyzer and can be transferred easily to a personal
computer. |