Acquisition Safety – Radio Frequency Radiation (RFR) Hazards

Naval Safety Center

Acquisition Safety – Radio Frequency Radiation (RFR) Hazards

IntroductionBackground Challenges RecommendationsConclusionResources

Introduction

RDR warning signExcessive levels of exposure to RFR can result in adverse acute (immediate) effects on people such as involuntary muscle contractions (electrostimulation), electrical shocks/burns (from touching metal objects in RFR fields), and excessive heating of tissue (thermal damage). High-level electromagnetic energy produced by RFR can also induce electrical currents or voltages that may cause premature activation of Electro-Explosive Devices (EEDs) and electrical arcs that may ignite flammable materials. Modern communication and radar transmitters aboard Navy ships can produce high-intensity Radio Frequency Radiation (RFR) environments that are potentially hazardous to 1) operating and maintenance personnel, 2) ordnance and fuels and, 3) associated equipment. The type of biological effect on humans from RFR depends on the frequency of the electromagnetic wave (see Background section for more information). The severity of the biological effect depends on the intensity (strength) of the RFR.

Planning to eliminate or minimize RFR hazards aboard ship should be inherent in the design phases of ship system acquisition. RFR protection and prevention measures must be considered during all phases of ship design, construction, use, maintenance, operation, and final disposal.

This section of the Acquisition Safety website outlines safety and operational concerns regarding RFR and discusses approaches to limit acquisition costs and risks in the ship design and development phase. Control of RFR system life-cycle costs and safety hazards during ship system operation and maintenance are also discussed. [See Resources section for more information on DON policy and procedures regarding electromagnetic energy radiation.]

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Background

Electromagnetic radiation consists of waves.
Figure 1 electromagnetic waves

Figure 1. Electromagnetic waves

A depiction of electric and magnetic energy moving together through space at the speed of light is shown in Figure 1.

All frequencies (or wavelengths) of electromagnetic energy are referred to as the electromagnetic spectrum, shown in Figure 2.

electromagnetic spectrum

Figure 2Electromagnetic Spectrum (Additional chart detailing military and civilian uses of RF and other spectra can be found at http://www.disa.mil/jsc/speccht.html).

Radio waves and microwaves emitted by transmitting antennas, illustrated in Figure 3, are antennaone form of electromagnetic energy. They are collectively referred to as “radiofrequency” radiation (RFR). RF energy includes frequencies ranging from 0 to 3000 GHz.

Microwaves, very short waves of electromagnetic energy, include frequencies ranging from around 300 megahertz (MHz) to 300 gigahertz (GHz). Microwaves are often referred to as “high frequency (HF) radio waves.” High frequency radio waves are used to transmit information from one place to another, because microwave energy can penetrate haze, light rain and snow, clouds, and smoke. Remote sensing is a common application of microwaves. There are two types of microwave remote sensing; 1) active and 2) passive.

Exposure to RF energy of sufficient intensity at frequencies between 3 kilohertz (kHz) and 300 GHz can adversely affect personnel, ordnance, and fuel. Potential exposures of this magnitude aboard ships are primarily associated with the operation of various radars and communication systems as illustrated in the photo below.

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Biological effects that result from heating of tissue by RF energy are often referred to as “thermal” effects. Exposure to very high levels of RF radiation can be harmful due to the ability of RF energy to heat biological tissue. In a healthy human body, the thermo-regulatory system will cope with the absorbed heat until it reaches the point at which it cannot maintain a stable body core temperature. Beyond this point the body may experience Flight deck aboard an aircraft carrierhyperthermia (heat exhaustion) and/or irreversible damage to human tissue if the cell temperature reaches about 43 degrees Celsius. There is a higher risk of heat damage for organs that have poor temperature control, such as the lens of the eye and the testes. The amount of absorbed energy to produce thermal stress is affected by the health of the individual (some medical conditions and medications may affect thermoregulation), environmental conditions (higher ambient temperature and relative humidity make it harder for the body to release heat), and physical activity (strenuous work can raise rectal temperature by itself).

Radiated energy can also result in high levels of induced and contact current through the body when in close proximity to high-power RF transmitting antennas. The biological hazards associated with electromagnetic radiation, established by the Institute of Electrical and Electronics Engineers (IEEE) C95.1 Standards Committee and adopted by the Tri-Service Electromagnetic Radiation Panel, is in DODINST 6055.11, Protection of DoD Personnel from Exposure to Radiofrequency Radiation and Military Exempt Lasers.

In addition to personnel concerns, RF fields may generate induced currents or voltages that could cause premature activation of electro-explosive devices in ordnance, equipment interference or sparks, and arcs that may ignite flammable materials and fuels.

NAVSEA OP 3565/NAVAIR 16-1-529/NAVELEX 0967-LP-624-6010/Volume I, Electromagnetic Radiation Hazards (U) (Hazards To Personnel, Fuel And Other Flammable Material) (U) [Distribution authorized to U.S. Government agencies and their contractors; administrative/operational use; 1 February 2003. Other requests for this document must be referred to the Naval Sea Systems Command (NAVSEA) (SEA 05).], and Volume II, Technical Manual, Electromagnetic Radiation Hazards (Hazards to Ordnance) [Note: certificate required], contain RF hazard (RADHAZ) guidance regarding hazards of RF exposure to personnel, fuels, and ordnance. It should be noted that the current industrial specifications for RADHAZ are contained in ANSI/IEEE C95.1-1992, which was used as a reference to create the combined Navy regulation NAVSEA OP3565 /NAVAIR 16-1-529.

 

https://www.public.navy.mil/navsafecen/Pages/acquisition/radio_frequency-radiation.aspx

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