surface radiation and edit into this paragraph that
limit for the specific project.
**************************************************************************
Provide each hopper with a fly ash level alarm utilizing factory installed
lead shielded nuclear type detectors. The detectors shall be single-point
gamma source and detection units. Provide lead shielding to cover the
detector and surrounding mounting surfaces and additional lead shielding
required around the source housing to limit the maximum measured surface
radiation at any surface accessible to personnel during normal operation to
[6x10-7 sievert/hr] [0.06 mR/hr] [_____] above ground radiation. Provide
manufacturer's standard nuclear warning sign. Provide detectors complete
with separately mounted electronic units which shall include a local high
level indicating light and relays for use with annunciation system herein
specified. Relays shall be rated 10 amperes, 120 volts AC, or 125 volts DC
continuous duty. Switch housing for all hoppers shall be dustproof and
shall be mounted at one easily accessible location. Locate all detector
and source electronics at the hopper control panel. Detector shall be
explosion proof and have waterjacketing. Alarm shall be able to withstand
vibration and temperatures up to 427 degrees C 800 degrees F. Provide the
source with a lockable shutter mechanism operated by an external handle to
totally isolate the beam when in the closed position. Electrical supply
shall be 120 volts, single phase, 60 hertz. Locate alarm at the 50 percent
hopper capacity level. Provide each hopper with two sensors--one at the
alarm level, and one at the empty level. Level reproductivity shall be
within one inch. All outdoor components shall operate between minus 40 and
93 degrees C 40 and 200 degrees F.
2.2.5.1
Hopper Source and Access Door
Source for each hopper shall be Cesium 137. Design source head with a
spring return off system in the event of remote cable actuator failure.
Interlock source with hopper access door(s) to prevent entry into hopper
unless source has been secured. Hopper access door key shall only be able
to open one pair of hopper doors.
2.2.5.2
Hopper Level Signals
Hopper level signals, based on hopper level status indicator system, shall
report to a microprocessor through a coaxial cable system. Provide each
hopper with two indicators, one for full and one for empty. A flashing
light shall indicate a wall buildup. Loss of power for any period of time
shall not require a recalibration. Provide microprocessor with a NEMA ICS 6,
Type 4 enclosure.
2.2.6
Ductwork
Section 15801N INDUSTRIAL VENTILATION AND EXHAUST, and SMACNA Industry
Practice, for [Class III] [Class IV] duct construction suitable for system
operating pressures and temperatures indicated. Provide duct materials,
fittings, hangers, supports, flanges, gaskets, expansion joints,
connections, relief vents, reinforcements, [and corrosion protection] for
the [existing] flue gases [to be] encountered in accordance with SMACNA
Industry Practice.
2.2.6.1
Ductwork to Cyclones
Design all ductwork between [boilers] [incinerator(s)] and cyclone(s) to be
self-cleaning. Ductwork meeting the following requirements will be
SECTION 15861N
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