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The calls keep coming
about radhaz areas on the new DDG 51-class ships. If you think you may be in such an area,
I urge you to use some time-critical operational risk management (ORM) and get yourself
and all others out of the area.
One of the best people to see with questions about
radhaz aboard Aegis ships is the combat systems officer of the watch (CSOOW). He has
access to charts that display all the radiation areas.
In the meantime, here is some guidance you can use when you
have people doing topside evolutions in various areas (refer to
the accompanying ship's diagram -requires Adobe Acrobat Reader to view):
Around the rigid-hulled inflatable boat (RHIB)
Antenna 2-2 should be silenced over frequencies: 5.5 to
9.5 MHz when personnel board the RHIB.
Antenna 2-3 should be silenced to do high-contact current on
metallic items, such as the inclined ladder, replenishment-at-sea (RAS) station,
watertight door at 01-28-P, and climber-safety rail on the 01 and 02 levels near or
beneath the antenna. Contact current is within limits when output power is reduced to 650
watts in the 17.5 and 22.5 MHz range. At frequencies between 22.5 and 30 MHz, power must
be reduced to 250 watts to be within acceptable limits.
RadHaz warning signs are to be posted at the RHIB stowage area
telling personnel to notify the communication center before doing daily boat reports and
system checks in the RHIB.
Around the vertical-launching system
Secure antenna 2-1 when the strike-down crane for the
forward, vertical-launching system (VLS) is operating.
Antennas 2-2 and 2-4 must be secured when operating the
strike-down crane for the aft VLS.
Around the CIWS
If people must work on the top radome of the CIWS mount
22, secure director No. 3.
CIWS maintenance personnel should stay aware that in the
maintenance mode, the radiation-cutout sectors can be bypassed, with the beam possibly
directed into occupied areas. Radiation from the track antenna can exceed the permissible
exposure levels (PELs) for an uncontrolled environment to a distance of 125 feet.
Around HF antenna 2-4, port side (02-292-1)
Contact current limits are exceeded to a distance of 14
feet from antenna 2-4. This antenna has no personnel barriers on the 02 level aft, and
personnel can receive severe RF burns. In the stowed position, contact current and
RF-voltage limits were exceeded on the antenna-stow stanchion, climber-safety rail, and
ammunition-access trunk. Personnel should not be allowed in the area around 02-312-1 when
antenna 2-4 is raised and operating.
The accompanying table A-1 (requires Adobe Acrobat Reader to view)
lists the radhaz control measures for DDG 51 flights I and II-class ships.
Although the Aegis platform is a high-energy radiation environment, avoid any suspected
area of radhaz. Use ORM to protect your Sailors from radiation burns and keep them safe
and healthy. If you have more questions, please feel free to contact us.
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