Do You Know The Different Underground Shelter Types?

Shelter Types

Bunker or Bomb Shelter

The bunker or bomb shelter is designed for actual direct hits of exploding weapons. Thebunker has no air filtration, life support, light, toilet, food, etc. It is a very short termstructure for a matter of minutes to a few hours and is usually underground.

EMP Shelter (E)

This type of shelter or structure is designed to operate above or below ground and eitherthe shelter hull or the mission essential equipment (MEE) inside the shelter must beshielded from EMP frequencies. EMP has no affect on humans, only to equipment with acomputer chip which gets disrupted by the EMP. To qualify as an EMP Shelter, theshelter must be operational during and after an electromagnetic pulse as defined in MIL-STD 188-125, “High Altitude Electromagnetic Pulse (HEMP) Protection from GroundBased C1 Facilities Performing Critical Time Urgent Missions”, July 1998. Faradaycages that shield from EMP must be made of aluminum or copper. Steel is usually notconductive enough to shield from EMP frequencies. EMP shielding must provide at least80 dB attenuation in the plane wave from 10 MHz to 1.5 GHz and magnetic attenuationof 2 dB at l KHz rising to 80 dB at 10 MHz in accordance with MIL-STD-188-125. Thistype of shelter must have an off-grid duration for life support of at least 6 months withthe more common duration being one year.

Tornado Shelter (T)

The tornado shelter is a very short term shelter usually less than one hour and designed toresist flying debris at up to 350 mph by an impact resistant hull or underground hull. Positive and negative pressure maximum is usually 5 psi. This type of shelter can beabove or below ground.
Hurricane Shelter (H)

The hurricane shelter needs to resists flying debris at winds up to 150 mph and shouldprovide life support for at least 5 days after the high winds are over. This type of sheltercan be above or below ground.

Fall Out Shelter

The fallout shelter is designed to shield shelterists from high doses of gamma radiation.The minimum gamma protection factor must to reduce the radiation doses to theshelterists to not more than 25 rems throughout the first 28 days following a weapondetonation of at least 100 KT. This type of shelter is not designed to shield from neutronradiation which is in the blast radius of a nuclear weapon. This type of shelter is usuallybelow ground.

Nuclear Blast Shelter (N)

The Nuclear Blast Shelter is designed to resist physical blast effects and shield from much higher doses of gamma radiation plus it must shield from neutron radiation. Air inlet and outlet manifolds must not be subject to damage from flying debris at the blast wind speed that the shelter is designed for. If a shelter is rated at 10 psi external pressure, it must be able to resist the 10 psi pressure and blast wind of 280 mph and also must beable to shield the shelterists from gamma and neutron radiation so the shelterists do notreceive more than 25 rems inside the shelter at the 10 psi blast pressure distance from atleast a 100 KT surface burst during the first 28 days. Radiation doses inside any type ofshelter are known as Total Rems In Shelter or TRS. A shelter with a TRS rating of 5-10indicates that this particular shelter will allow not more than 5 rems from overhead andfrom the entranceway to enter the shelter within the first 28 days after detonation of agiven size weapon. Well established gamma and neutron radiation doses from hundredsof actual nuclear weapons tests are known at various distances from ground zero atvarious psi ranges. 1 The Nuclear Blast shelter must provide at least 28 days of lifesupport off-grid plus any recovery time after the blast. Air filtration must include aHEPA filter to remove fallout particles at 99.99% efficiency at 0.3 microns. The HEPAfilter must be able to be changed from inside the shelter, preferably without coming intocontact with the filter element, after the first 24-48 hours. Otherwise the HEPA filter willemit radiation doses into the shelter. Activated carbon must be used to removeradioactive iodine gas present in the air. This type of shelter is almost always belowground.

Chemical Warfare Shelter (C)

A Chemical Warfare Shelter is not designed to resist any type of blast effect and isdesigned with air filtration equipment to remove all chemical warfare agents from theincoming air to the shelter. The particular type of carbon used to remove chemicalwarfare agents is called TEDA carbon. The time that the chemical agent is in contactwith the carbon is called residence time. To remove chemical warfare agents requires aminimum residence time of 0.25 seconds. How long the carbon can remove the agentsfrom the air is based on the number of pounds of TEDA carbon in the filter. Common airfiltration equipment uses 1 pound of TEDA carbon per 100 cfm for approximately 3 days.Military air filtration equipment typically uses 15 lbs. of TEDA carbon per 100 cfm ofincoming air for 45 days of operation. A good chemical air filter should have a way oftesting for chemical agents in the air so the shelterist does not have to exit the shelter totest for chemical agents. This type of shelter does not require resistance to blast, groundshock, or radiation. Some chemical warfare shelters are tents.

Biological Warfare Shelter (B)

A Biological Warfare Shelter requires a HEPA or ULPA air filter to remove aerosols or dust particles that the biological agent is carried on. The HEPA filter must have a99.99% efficiency at 0.3 u or microns. This type of shelter does not require resistance toblast, ground shock, or radiation therefore some biological warfare shelters are tents.
1 McCarthy, Walton M.E., PRINCIPLES OF PROTECTION, THE
US HANDBOOK OF NBC WEAPON FUNDAMENTALS AND SHELTER ENGINEERING DESIGN STANDARDS, 6TH edition,2013, 777 pp. Brown books, Tables 13-2, 13-3, 13-4.Nuclear-Biological-Chemical- EMP (NBCE)
This type of shelter is designed for severe environments of all known weapon typesmentioned above.

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