High Altitude Electromagnetic Pulse (HEMP). The detonation of one
nuclear device at high altitude produces an extremely intense electromagnetic
pulse (EMP) that can illuminate surfaces of a large geographical area without
the other effects of nuclear detonation being present (blast, thermal shock
and nuclear radiation). Unless HEMP protective measures are provided, much of
the nations sophisticated electronic communications systems may be rendered
useless. The primary effect of HEMP is the production of large transient
voltages and currents in conductors such as power and telephone lines and
electronic equipment cabling. The criteria for facility HEMP protection is
covered in NAVFAC Design Manual DM-12.02.
Hazards of Electromagnetic Radiation to Personnel (HERP).
Electromagnetic radiation, especially in the microwave frequency region, can
be extremely damaging when absorbed by the body. The electromagnetic
radiation can also induce voltage between metal structures and earth. These
induced voltages may cause shock or RF burns to personnel. These threats can
be considerably reduced by EMI shielding, proper bonding, and grounding of
metallic structures. NAVELEX 0101,106, Electromagnetic Compatibility and
Electromagnetic Radiation Hazards, contains technical information on Radiation
Hazards of Electromagnetic Radiation to Ordnance (HERO).
Electromagnetic radiation, under certain conditions, can detonate electro-
explosive devices (EED) contained in ordnance material. The maximum allowable
electromagnetic field intensity for various classifications of ordnance is
defined in NAVSEA OP-3565/NAVAIR 16-1-529, Electromagnetic Radiation Hazards.
Hazards of Electromagnetic Radiation to Fuel (HERF). Electrical
arcs or sparks caused by electromagnetic radiation induced voltages create a
potential hazard at locations where fuel vapors may be present. The ability
of an arc to ignite a vapor-air mixture depends upon the susceptibility of the
fuels to ignition, the presence of a flammable fuel-air mixture, the energy
contained in and the length and duration of the arc. National Fire Protection
Association (NFPA) Standard No. 407, Aircraft Fuel Servicing, Standard for,
and NAVELEX 0101,106, Electromagnetic Compatibility and Electromagnetic
Radiation Hazards, contains information on the potential hazards to fuels.
Shielding for Communication-Electronics (C-E) Facilities. When a
facility is to contain sensitive C-E equipment and there are no regulations
mandating EMI control of the surrounding environment, it may be necessary to
include shielding in the structure to protect the C-E equipment from the
external ambient EMI. This type of facility EMC shielding may be necessary to
protect equipment such as computers from malfunction or damage. The level of
shielding effectiveness required and the frequency range of the required
shielding must be calculated, based on the background EM ambient and equipment
susceptibility surveys obtained from the EMC evaluation. These surveys are
provided by the SPAWARSYSCOM at the request of the sponsor.
Electromagnetic Compatibility (EMC) Evaluation. An electromagnetic
compatibility (EMC) evaluation should be conducted during the planning phase.
The EMC evaluation should identify environmental electromagnetic interference
from all measurable or known sources in vicinity of the site location. This
part of the evaluation is the responsibility of SPAWARSYSCOM but is usually
performed at the request of the sponsor. An equipment study should also be