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Conference Article: Twenty-five years of Brown Boveri experience in development, design and fabrication of circulators for HTGR

Stoelzl, D. (Brown, Boveri und Cie A.G., Mannheim (Germany, F.R.))

Abstract

The two circulators for the AVR experimental reactor in Juelich, Federal Republic of Germany, were supplied. The circulators, which are equipped with oil bearings, have been operating troublefree since the start of commissioning in 1966. As a consequence of a water ingress into the reactor resulting from a steam generator damage one bearing was replaced in 1977 after 72,000 operating hours. Up to the present date, each of the circulators has scored 115,000 hours of operation, one of them without any disassembly. In the THTR 300 in Schmehausen, Federal Republic of Germany, 6 BBC circulators are in operation. The insertable circulator units equipped with oil bearings have successfully proven their operating capability without any problems during the commissioning phase and the 100% power operation which was started recently. Currently active magnetic bearings are being developed for advanced gas-cooled reactors such as the HTR 100, the HTR 500 and the heating reactor after excellent results have been furnished by a small prototype in a test loop. This ADI circulator has since scored more than 15,000 operating hours without any trouble. A retainer bearing test stand also equipped with active magnetic bearings has been in operation for nearly 2 years. This test stand serves for developing the conditions for safe rundown of the rotors of even the largest circulators after the magnetic bearings have been deenergized unintentionally. Development work is conducted on the prototype of a safety-relevant circulator held in magnetic bearings, to be used for decay heat removal in the HTR 500. The original aim to have circulators without auxiliary medium for bearing lubrication will thus be reached. The advantages to be obtained in process and systems design are a supplementary support to the inherent safety characteristics of high-temperature reactors. Another advantage of these bearings is cost reduction.

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key words: Gas Cooled Reactor, Nuclear Technology
Reference:
Specialists' meeting on gas-cooled reactor coolant circulator and blower technology. San Diego, CA (USA). 30 Nov - 2 Dec 1987
International Atomic Energy Agency, Vienna (Austria). International Working Group on Gas-Cooled Reactors
IWGGCR--17, pp:53-59