DOE 2000. - Waste Isolation Pilot Plant - U.S. Department of Energy

WIPP RH PSAR DOE/WIPP-03-3174 CHAPTER 4
4.6.1.4 Safety Considerations and Controls
Failure of the normal distribution system or any of its components will not affect safe conditions of the
WIPP facilities. Upon loss of normal off-site power, the EFB isolation valves fail to the filtration mode.
The simplified single-line diagram for the normal and manually switched backup loads is shown in
Figures 4.6-2a and 4.6-2b (switching devices and equipment are symbolically represented).
4.6.2 Compressed Air
The compressed air system is Design Class IIIB. The system is diverse in the types and sizes of
compressors used, and redundancy is provided for the main plant air compressors, salt hoist house, and
the underground. All are electrically driven except for the diesel powered backup compressor in the
underground.
The piping system consists of runs of 2, 4, and 6 in (5, 10, and 15 cm) pipe connecting the two
compressor buildings to the WHB, Support Building, EFB, salt hoist house, and Safety Building. A
pipe-run down the waste shaft serves the underground. Each building and the underground can be
isolated from the system.
There are two general types of compressors in use at the WIPP. The majority are reciprocating, but the
primary main plant air compressors and the underground backup compressor are rotary screw type. All
are either single- or two-stage units; the backup main plant air compressors are the non-lubricated type
for oil free output air.
The primary main plant air compressors are two single stage rotary screw units of 250 horsepower with a
maximum capacity for each unit of 1,155 cfm (32.7 m 3 /m) at a system pressure of 125 psi
(8.8 kg/cm 2 ). Cooling for these compressors is accomplished with a fin and tube heat exchanger and
cooling fan placed in the lubricating oil system.
The secondary main plant air compressors are two, two-stage, double acting reciprocating units of 200
horsepower and maximum capacity of 1,000 cfm (28.32 m 3 /m) at 125 psi (8.8 kg/cm 2 ). These
compressors are the only water cooled units on site, using a closed loop system, pumping a mixture of
water and ethylene glycol antifreeze through a fin and tube heat exchanger with four electrically driven
cooling fans.
A twin tower desiccant air dryer with prefilters and after filters is located just downstream of the
compressors at each of the above installations to provide clean, moisture-free, compressed air dried to a
dew point of 0EF (-18EC). A 1,000 gal (3785 L) capacity air receiver is located just downstream of the
dryer at each location and connected to the site piping system.
The WHB and EFB employ desiccant air dryers similar to the large units installed at the main
compressor buildings but much smaller. These dryers provide additional filtering of the air and lower the
dew point to -40EF (-40EC). The Plant Air System ends at these dryers and the Instrument Air System
begins. Instrument quality air is then used to operate dampers and control systems for the underground
ventilation system and HVAC systems in the above mentioned buildings.
The salt hoist house has a backup installation similar to those described above but uses a refrigerated air
dryer instead of the desiccant type. This unit provides air for operation of the hoist brakes in the event of
a loss of plant air.
4.6-3 January 28, 2003