D.I. Will and J.A. Wootress

The booster linac is cooled by liquid helium which is thermally shielded by liquid nitrogen. This liquid nitrogen is delivered in lots of ~6,000 gallons by semitrailer tanker. In 1995 liquid nitrogen consumption of 198,200 gallons was 12% less than that in pre-1994 years because a precool heat-exchanger leak now prohibits the use of liquid nitrogen assist in our Koch Process Systems 2830 Helium Refrigerator. Helium is purchased as high purity, bulk gas and liquified by our helium refrigerator. Usage of 107,200 Standard Cubic Feet (SCF) in 1995 was down 52% from that in the peak use year, 1993, when the leaky heat exchanger caused substantial loss. Usage was down 27% from the mean for 1989 through 1992, more typical years.

The following table summarizes our maintenance from January 1, 1995 to December 31, 1995:

This final table shows screw compressor history here as of March 12, 1996:

Excluding the RS-2 compressor pump core which was stopped and started often to adjust compressor capacity to refrigeration needs (before we learned that such compact 100 HP motors have only a limited number of starts before failure), mean pump core lifetime is 51,597 hours with three of these four cores still running.