The Effects of Nuclear War
Chapter 2
CIVIL DEFENSE MEASURES
Civil defense seeks to protect the population, protect industry, and improve the quality of postattack life, institutions, and values. This section considers several measures that support these goals.
Population Protection
People near potential targets must either seek protective shelter or evacuate from threatened areas to safer surroundings; if not at risk from immediate effects, they must still protect themselves from fallout. Both forms of protection depend on warning, shelter, supplies, life-support equipment (e. g., air filtration, toilets, communication devices), instruction, public health measures, and provision for rescue operations. In addition, evacuation involves transportation, This section examines each form of protection.
Blast Shelters
Some structures, particularly those designed for the purpose, offer substantial protection against direct nuclear effects (blast, thermal radiation, ionizing radiation, and related effects such as induced fires). Since blast is usually the most difficult effect to protect against, such shelters are generally evaluated on blast resistance, and protection against other direct effects is assumed. Since most urban targets can be destroyed by an overpressure of 5 to 10 psi, a shelter providing protection against an overpressure of about 10 psi is called a blast shelter, although many blast shelters offer greater protection. Other shelters provide good protection against fallout, but little resistance to blast–such “fallout shelters” are discussed in the next section. Blast shelters generally protect against fallout, but best meet this purpose when they contain adequate life-support systems. (For example, a subway station without special provisions for water and ventilation would make a good blast shelter but a poor fallout shelter. )
Nuclear explosions produce “rings” of various overpressures. If the overpressure at a given spot is very low, a blast shelter is unnecessary; if the overpressure is very high (e. g., a direct hit with a surface burst), even the best blast shelters will fail. The “harder” the blast shelter (that is, the greater the overpressure it can resist), the greater the area in which it could save its occupants’ lives. Moreover, if the weapon height of burst (HOB) is chosen to maximize the area receiving 5 to 10 psi, only a very small area (or no area at all) receives more than 40 to 50 psi. Hence, to attack blast shelters of 40 to 50 psi (which is a reasonably attainable hardness), weapons must be detonated at a lower altitude, reducing the area over which buildings, factories, etc., are destroyed.
The costs of blast shelters depend on the degree of protection afforded and on whether the shelter is detached or is in a building constructed for other purposes. However, a large variation in costs occurs between shelters added to existing buildings and those built as part of new construction. The installation of shelters in new construction, or “slanting,” is preferable, but it could take as long as 20 years for a national policy of slanting to provide adequate protection in cities.
An inexpensive way to protect population from blast is to use existing underground facilities such as subways, where people can be located for short periods for protection. If people must remain in shelters to escape fallout, then life-support measures requiring special preparation are needed.
Other lethal nuclear effects cannot be overlooked. Although, as noted above, blast shelters usually protect against prompt radiation, the shelters must be designed to ensure that this is the case.
Another problem is protection against fallout. If a sheltered population is to survive fallout, two things must be done. First, fallout must be prevented from infiltrating shelters through doors, ventilation, and other conduits. Other measures to prevent fallout from being tracked or carried into a shelter must also be taken. More important, the shelter must enable its occupants to stay inside as long as outside radiation remains dangerous; radiation doses are cumulative and a few brief exposures to outside fallout may be far more hazardous than constant exposure to a low level of radiation that might penetrate into a shelter.
Since radiation may remain dangerous for periods from a few days to several weeks, each shelter must be equipped to support its occupants for at least this time. Requirements include adequate stocks of food, water, and necessary medical supplies, sanitary facilities, and other appliances. Equipment for controlling temperature, humidity, and “air quality” standards is also critical. With many people enclosed in an airtight shelter, temperatures, humidity, and carbon dioxide content increase, oxygen availability decreases, and fetid materials accumulate. Surface fires, naturally hot or humid weather, or crowded conditions may make things worse. If unregulated, slight increases in heat and humidity quickly lead to discomfort; substantial rises in temperature, humidity, and carbon dioxide over time could even cause death. Fires are also a threat to shelterers because of extreme temperatures (possibly exceeding 2,000° F) and carbon monoxide and other noxious gases. A large fire might draw oxygen out of a shelter, suffocating shelterers. World War II experience indicates that rubble heated by a firestorm may remain intolerably hot for several days after the fire is put out.