Editing Fallout shelter (section)

== Details of shelter construction ==
[[File:Swiss Civil Defense Bunker (15710856390).jpg|thumb|Door of a public fallout shelter in Switzerland (2014).]]
[[File:Big german fire door 1.png|thumb|Large fire door, sealing a fallout and air raid shelter inside the basement parking garage of a hotel in Germany.]]

=== Shielding ===
A basic fallout shelter consists of shields that reduce gamma ray exposure by a factor of 1000. The required shielding can be accomplished with 10 times the [[Radiation protection#Shielding design|thickness]] of any quantity of material capable of cutting gamma ray exposure in half. Shields that reduce gamma ray intensity by 50% (1/2) include {{convert|1|cm|in|1}} of lead, {{convert|6|cm|in|1|abbr=on}} of concrete, {{convert|9|cm|in|1|abbr=on}} of packed earth or {{convert|150|m|ft|sigfig=1}} of air. When multiple thicknesses are built, the shielding multiplies. Thus, a practical fallout shield is ten halving-thicknesses of packed earth, reducing gamma rays by approximately 1024 times (2<sup>10</sup>).<ref>{{cite web|url=http://www.derose.net/steve/guides/emergency/hardened.html|title=Halving-thickness for various materials|work=The Compass DeRose Guide to Emergency Preparedness&nbsp;– Hardened Shelters|access-date=August 15, 2012|archive-date=January 22, 2018|archive-url=https://web.archive.org/web/20180122235733/http://www.derose.net/steve/guides/emergency/hardened.html|url-status=dead}}</ref>

Usually, an expedient purpose-built fallout shelter is a trench; with a strong roof buried by 1&nbsp;m (3&nbsp;ft) of earth. The two ends of the trench have ramps or entrances at right angles to the trench, so that gamma rays cannot enter (they can travel only in straight lines). To make the overburden waterproof (in case of rain), a plastic sheet may be buried a few inches below the surface and held down with rocks or bricks.<ref name=NWSS6>{{cite book|last=Kearny|first=Cresson H|title=Nuclear War Survival Skills|year=1986|publisher=Oak Ridge National Laboratory|location=Oak Ridge, TN|isbn=0-942487-01-X|pages=37–45|url=http://www.oism.org/nwss/s73p916.htm|quote="The 3-foot thickness of earth shown (or a 2-foot thickness of concrete) will provide an effective barrier, attenuating (absorbing) about 99.9%, of all gamma rays from fallout." "A right-angle turn, either from a vertical or horizontal entry, causes a reduction of about 90%." "...a large piece of 4-mil-thick polyethylene was placed over the mound. This waterproof material served as a "buried roof" after it was covered with more earth."}}</ref>

Blast doors are designed to absorb the shock wave of a nuclear blast, bending and then returning to their original shape.<ref name=lostworlds>{{cite episode|title= Secret U.S. Bunkers|series=[[Lost Worlds (TV series)|Lost Worlds]]|network=The History Channel|date=August 29, 2007|number=18}}</ref>

=== Climate control ===
Dry earth is a reasonably good thermal insulator, but over several weeks of habitation, a shelter will become dangerously hot.<ref name=NWSS7/> The simplest form of effective fan to cool a shelter is a wide, heavy frame with flaps that swing in the shelter's doorway and can be swung from hinges on the ceiling. The flaps open in one direction and close in the other, pumping air. (This is a [[Kearny air pump]], or KAP, named after the inventor, [[Cresson Kearny]].)

Unfiltered air is safe, since the most dangerous fallout has the consistency of sand or finely ground pumice.<ref name=NWSS7/> Such large particles are not easily ingested into the soft tissues of the body, so extensive filters are not required. Any exposure to fine dust is far less hazardous than exposure to the fallout outside the shelter. Dust fine enough to pass the entrance will probably pass through the shelter.<ref name=NWSS7>{{cite book|last=Kearny|first=Cresson H|title=Nuclear War Survival Skills |year= 1986|publisher=Oak Ridge National Laboratory|location=Oak Ridge, TN|isbn=0-942487-01-X |pages=51–56 |url=http://www.oism.org/nwss/s73p917.htm}}</ref> Some shelters, however, incorporate [[Chemical, biological, radiological, and nuclear|NBC]]-filters for additional protection.

=== Locations ===
Effective public shelters can be the middle floors of some tall buildings or parking structures, or below ground level in most buildings with more than 10 floors. The thickness of the upper floors must form an effective shield, and the windows of the sheltered area must not view fallout-covered ground that is closer than 1.5&nbsp;km (1&nbsp;mi). One of Switzerland's solutions is to use road tunnels passing through the mountains, with some of these shelters being able to protect tens of thousands.<ref name=BBC1>{{cite news|last=Foulkes|first=Imogen|title=Swiss still braced for nuclear war|url=http://news.bbc.co.uk/2/hi/programmes/from_our_own_correspondent/6347519.stm|access-date=August 15, 2012|newspaper=BBC News, Switzerland|date=February 10, 2007}}</ref>

Fallout shelters are not always underground. Above ground buildings with walls and roofs dense enough to afford a meaningful [[Radiation protection#Shielding design|protection factor]] can be used as a fallout shelter.<ref>Monteyne, David. ''Fallout Shelter: Designing for Civil Defense in the Cold War.'' Minneapolis: University of Minnesota, 2011. Print.</ref>

=== Contents ===
A battery-powered radio may be helpful to get reports of fallout patterns and clearance. However, radio and other electronic equipment may be disabled by [[electromagnetic pulse]]. For example, even at the height of the Cold War, [[Electromagnetic pulse#Practical considerations for nuclear EMP|EMP protection]] had been completed for only 125 of the approximately 2,771 radio stations in the United States [[Emergency Broadcast System]]. Also, only 110 of 3,000 existing Emergency Operating Centers had been protected against EMP effects.<ref name=NWSS4>{{cite book|last=Kearny|first=Cresson H|title=Nuclear War Survival Skills|year=1986|publisher=Oak Ridge National Laboratory|location=Oak Ridge, TN|isbn=0-942487-01-X|pages=24|url=http://www.oism.org/nwss/s73p914.htm}}</ref> The Emergency Broadcast System has since been supplanted in the United States by the [[Emergency Alert System]].

The reference ''Nuclear War Survival Skills'' includes the following supplies in a list of "Minimum Pre-Crisis Preparations": one or more shovels, a pick, a bow-saw with an extra blade, a hammer, and {{convert|4|mil|mm|order=flip|1|abbr=on}} polyethylene film (also any necessary nails, wire, etc.); a homemade shelter-ventilating pump (a [[Kearny air pump|KAP]]); large containers for water; a plastic bottle of sodium hypochlorite bleach; one or two [[Kearny Fallout Meter|KFMs]] (Kearny fallout meters) and the knowledge to operate them; at least a 2-week supply of compact, nonperishable food; an efficient portable stove; wooden matches in a waterproof container; essential containers and utensils for storing, transporting, and cooking food; a hose-vented {{convert|5|usgal|L|order=flip|sigfig=1}} can, with heavy plastic bags for liners, for use as a toilet; tampons; insect screen and fly bait; any special medications needed by family members; pure [[potassium iodide]], a {{convert|2|usfloz|mL|order=flip|sigfig=1|abbr=on}} bottle, and a medicine dropper; a first-aid kit and a tube of antibiotic ointment; long-burning candles (with small wicks) sufficient for at least 14 nights; an [[Nuclear War Survival Skills#Light|oil lamp]]; a flashlight and extra batteries; and a transistor radio with extra batteries and a metal box to protect it from electromagnetic pulse.<ref name=NWSS17>{{cite book|last=Kearny|first=Cresson H|title=Nuclear War Survival Skills|year=1986|publisher=Oak Ridge National Laboratory|location=Oak Ridge, TN|isbn=0-942487-01-X|pages=133–134|url=http://www.oism.org/nwss/s73p927.htm}}</ref>

Inhabitants should have water on hand, {{convert|1|-|2|usgal|L|order=flip|sigfig=1}} per person per day. Water stored in bulk containers requires less space than water stored in smaller bottles.<ref>{{cite journal|last=Hammes|first=JA|title=Fallout shelter survival research|journal=Journal of Clinical Psychology|year=1966|volume=22|issue=3|pages=154–159|doi=10.1002/1097-4679(196607)22:3<344::aid-jclp2270220330>3.0.co;2-v|pmid=5917900}}</ref>

==== Kearny fallout meter ====
Commercially made [[Geiger counter]]s are expensive and require frequent calibration. It is possible to construct an [[electroscope#Gold-leaf electroscope|electrometer]]-type radiation meter called the [[Kearny fallout meter]], which does not require batteries or professional calibration, from properly-scaled plans with just a coffee can or pail, gypsum board, [[monofilament fishing line]], and aluminum foil.<ref name=A>{{cite book|last=Kearny|first=Cresson H|title=The KFM, A Homemade Yet Accurate and Dependable Fallout Meter|year=1978|publisher=Oak Ridge National Laboratory|location=Oak Ridge, TN|url=http://www.ornl.gov/~webworks/cppr/y2001/rpt/112538.pdf|url-status=dead|archive-url=https://web.archive.org/web/20040325094514/http://www.ornl.gov/~webworks/cppr/y2001/rpt/112538.pdf|archive-date=March 25, 2004|df=mdy-all}}</ref> Plans are freely available in the public domain in the reference ''Nuclear War Survival Skills'' by [[Cresson Kearny]].<ref name=NWSS11>{{cite book|last=Kearny|first=Cresson H|title=Nuclear War Survival Skills|year=1986|publisher=Oak Ridge National Laboratory|location=Oak Ridge, TN|isbn=0-942487-01-X|pages=95–100|url=http://www.oism.org/nwss/s73p921.htm}}</ref>