Radiation Hazards

RF energy in itself can be a hazard.  Radiation Hazard (RADHAZ) is typically mitigated by separation from the emitter source and these are the typical warning signs posted. There are three classes of RADHAZ:

1. Hazard of Electromagnetic Radiation to Personnel (HERP) is the danger to personnel from the absorption of electromagnetic energy by the human body.  Personnel hazards are associated with the absorption of RF energy above certain power levels in certain frequency bands for certain lengths of time.  Its all spelled out in the DoD Instruction noted. DoD Instruction 6055.11 defines the allowable amounts in terms of how long personnel may be exposed to RF fields of particular intensities at particular frequencies. You may have seen warning signs such as this one posted aboard ships.
2. Hazard of Electromagnetic Radiation to Fuel (HERF) is the hazard associated with the possibility of igniting fuel or other volatile materials through RF energy induced arcs or sparks.  It takes a certain amount of arc energy to ignite a fuel and modern fuels like JP-5 are much safer than older fuels like JP-4. You can see how that might be a concern aboard and aircraft carrier.  Fortunately there are many operational safeguards against this problem and many of the newer fuels such as JP-5 are much harder to ignite.
3. Hazard of Electromagnetic Radiation to Ordnance (HERO) refers to the susceptibility of electroexplosive devices the RF energy.  These EEDs or EIDs are used to detonate explosives, launch ejection seats, cut tow cables, etc.  Modern communication and radar transmitters can produce high electromagnetic environments that are potentially hazardous to ordnance.  These environments can cause premature actuation of the following sensitive, electrically initiated devices

HERP is the danger to personnel from the absorption of electromagnetic energy by the human body. Personnel hazards are associated with the absorption of RF energy above certain power levels in certain frequency bands for certain lengths of time. Its all spelled out in the DoD Instruction noted. DoD Instruction 6055.11 defines the allowable amounts in terms of how long personnel may be exposed to RF fields of particular intensities at particular frequencies. You may have seen warning signs such as this one posted aboard ships.

HERO refers to the susceptibility of electro-explosive devices (EEDs) to RF energy. These EEDs or EIDs are used to detonate explosives, launch ejection seats, cut tow cables, etc. Modern communication and radar transmitters can produce high electromagnetic environments that are potentially hazardous to ordnance. These environments can cause premature actuation of the following sensitive, electrically initiated devices including: Explosive Elements Known As EEDs

• Burn Wires And Fusible Links
• Slapper Detonators
• Exploding Foil Initiators
• Laser Initiators
• Electronic Safe And Arm Device (ESAD)

HERO is especially important today because of the increased use of Joint or International military operations. The Navy has a very robust HERO program but that may not be the case with the Army, Air Force or even the Special Forces. When they bring their ordnance aboard ship (and the Special Forces has all kinds of special things that go BOOM), there may have to be severe operating restriction imposed if the HERO status of this ordnance isn't well known.