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How Deep Does A Shelter Have To Be?

Let’s looks at what earth above the shelter actually does. First, it provides radiation shielding for both gamma and neutron radiation. Secondly, it provides counter buoyancy to keep the shelter in the ground during high water tables. Third, it provides mass to keep the shelter temperature stable and keep it from overheating when people live inside. In tactical situations we could talk about effects of artillery shells falling on or near the shelter but that is another whole area that will not be addressed here.

Radiation Shielding Overhead

Every shelter has a radiation design dose which is the type of radiation and the level of radiation the shelter is designed to resist. There is an Overhead Radiation Design Dose and an Entranceway Radiation Design Dose. We will focus here on the Overhead Radiation Design Dose.

Let’s arbitrarily set the radiation design dose based on a 100 KT surface burst nuclear weapon of 50% fission and 50% fusion. Let’s also set the design pressure of the shelter to resist 10 psi of overpressure which is 0.9 miles away from ground zero for this size weaponi.

There are many materials that can be used to shield radiation but there is no material cheaper than earth. A neutron radiation dose is reduced in half when passing through 4.7 inches of earth. Gamma radiation is reduced in half when passing through 5.5 inches of earth. A very handy table used to determine the Overhead Radiation Design Dose is shown below.

GAMMA AND NEUTRON RADIATION DOSES COMBINED IN REMS INSIDE A SHELTER BASED ON EARTH COVER
100 KT SURFACE BURST
Dist. GZ MSD 0.5 MI 0.6 MI 0.7 MI 0.8 MI 0.9 MI 1 MI 10 MI 25 MI 50 MI 100 MI
Overpressure psi 200 30 21 15 12 10 8 0 0 0 0
Initial Gamma rems 25,000 25,000 10,000 4,500 2,000 1,200 500 0 0 0 0
Fallout Gamma rems 9,554 9,554 9,554 9,554 9,554 9,554 9,554 5,800 3,800 375 100
Neutron rems 1,000,000 80,000 25,000 15,000 7,000 4,000 1,600 0 0 0 0
Earth-inch                      
5.5 517,277 57,277 22,277 14,527 9,277 7,377 5,827 2,900 1,900 188 50
11.0 258,639 28,639 11,139 7,264 4,639 3,689 2,914 1,450 950 94 25
16.5 129,319 14,319 5,569 3,632 2,319 1,844 1,457 725 475 47 13
22.0 64,660 7,160 2,785 1,816 1,160 922 728 363 238 23 6
27.5 32,330 3,580 1,392 908 580 461 364 181 119 12 3
33.0 8,353 1,165 501 337 236 199 170 91 59 6 2
38.5 4,176 583 251 169 117 100 85 45 30 3 1
44.0 2,088 291 125 84 59 50 42 23 15 1 0
49.5 1,044 145 62 42 30 25 22 11 7 1 0
55.0 522 73 31 21 14 13 11 6 4 0 0
60.5 261 37 16 11 8 6 5 3 2 0 0
66.0 69 18 7 5 3 3 2 1 1 0 0
71.5 35 6 3 2 1 1 1 1 0 0 0
77.0 17 3 1 1 1 1 1 0 0 0 0
82.5 9 2 1 0 0 0 0 0 0 0 0
88.0 5 1 0 0 0 0 0 0 0 0 0
93.5 2 0 0 0 0 0 0 0 0 0 0
99.0 0 0 0 0 0 0 0 0 0 0 0
104.5 0 0 0 0 0 0 0 0 0 0 0
110.0 0 0 0 0 0 0 0 0 0 0 0
115.5 0 0 0 0 0 0 0 0 0 0 0
121.0 0 0 0 0 0 0 0 0 0 0 0
PRINCIPLES OF PROTECTION, The US Handbook of NBC Weapons Fundamentals and Shelter Engineering Design Standards, 6th edition, 2013, Walton McCarthy M.E. Brown Books.
Effects Rems
50% Lethal 200-450
radiation sickness 50-200
blood effect 25-50
safe 0-25

Radiation Shielding Materials

RADIATION SHIELDING MATERIAL THICKNESS IN INCHES
Figure 13.1 (Principles of Protection p. 420)

HVL PF Lead
705 #/ft3
Steel
490 #/ft3
Concrete
146 #/ft3
Earth
100 #/ft3
Wood
40 #/ft3
Gamma Neutron Gamma Neutron Gamma Neutron Gamma Neutron Gamma Neutron
1 2.0 0.8 3.5 1.2 2.0 3.9 4.7 5.5 4.7 11.8 3.9
2 4.0 1.6 7.0 2.4 4.0 7.8 9.4 11.0 9.4 23.6 7.8
3 8.0 2.4 10.5 3.6 6.0 11.7 14.1 16.5 14.1 35.4 11.7
4 16.0 3.2 14.0 4.8 8.0 15.6 18.8 22.0 18.8 47.2 15.6
5 32.0 4.0 17.5 6.0 10.0 19.5 23.5 27.5 23.5 59.0 19.5
6 64.0 4.8 21.0 7.2 12.0 23.4 28.2 33.0 28.2 70.8 23.4
7 128.0 5.6 24.5 8.4 14.0 27.3 32.9 38.5 32.9 82.6 27.3
8 256.0 6.4 28.0 9.6 16.0 31.2 37.6 44.0 37.6 94.4 31.2
9 512.0 7.2 31.5 10.8 18.0 35.1 42.3 49.5 42.3 106.2 35.1
10 1,024.0 8.0 35.0 12.0 20.0 39.0 47.0 55.0 47.0 118.0 39.0
11 2,048.0 8.8 38.5 13.2 22.0 42.9 51.7 60.5 51.7 129.8 42.9
12 4,096.0 9.6 42.0 14.4 24.0 46.8 56.4 66.0 56.4 141.6 46.8
13 8,192.0 10.4 45.5 15.6 26.0 50.7 61.1 71.5 61.1 153.4 50.7
14 16,384.0 11.2 49.0 16.8 28.0 54.6 65.8 77.0 65.8 165.2 54.6
15 32,768.0 12.0 52.5 18.0 30.0 58.5 70.5 82.5 70.5 177.0 58.5
16 65,536.0 12.8 56.0 19.2 32.0 62.4 75.2 88.0 75.2 188.8 62.4
17 131,072.0 13.6 59.5 20.4 34.0 66.3 79.9 93.5 79.9 200.6 66.3
18 262,144.0 14.4 63.0 21.6 36.0 70.2 84.6 99.0 84.6 212.4 70.2
19 524,288.0 15.2 66.5 22.8 38.0 74.1 89.3 104.5 89.3 224.2 74.1
20 1,048,576.0 16.0 70.0 24.0 40.0 78.0 94.0 110.0 94.0 236.0 78.0
21 2,097,152.0 16.8 73.5 25.2 42.0 81.9 98.7 115.5 98.7 247.8 81.9
22 4,194,304.0 17.6 77.0 26.4 44.0 85.8 103.4 121.0 103.4 259.6 85.8
23 8,388,608.0 18.4 80.5 27.6 46.0 89.7 108.1 126.5 108.1 271.4 89.7
24 16,777,216.0 19.2 84.0 28.8 48.0 93.6 112.8 132.0 112.8 283.2 93.6
25 33,554,432.0 20.0 87.5 30.0 50.0 97.5 117.5 137.5 117.5 295.0 97.5
26 67,108,864.0 20.8 91.0 31.2 52.0 101.4 122.2 143.0 122.2 306.8 101.4
27 134,217,728.0 21.6 94.5 32.4 54.0 105.3 126.9 148.5 126.9 318.6 105.3
28 268,435,456.0 22.4 98.0 33.6 56.0 109.2 131.6 154.0 131.6 330.4 109.2
29 536,870,912.0 23.2 101.5 34.8 58.0 113.1 136.3 159.5 136.3 342.2 113.1
30 1,073,741,824.0 24.0 105.0 36.0 60.0 117.0 141.0 165.0 141.0 354.0 117.0

Note: The initial gamma radiation HVL varies only slightly from that of fallout gamma and is therefore treated the same in this table

Example: For shielding against gamma radiation, a protection factor of 1,024 would be provided by 8.0 inches of lead, 12.0 inches of steel, 39.0 inches of concrete,, 55.0 inches of earth, or 118 inches of wood.

PRINCIPLES OF PROTECTION, The US Handbook of NBC Weapon Fundamentals and Shelter Engineering Design Standards, Walton McCarthy, 727 pp. 2013, 6th edition, Brown Books.

Different material thickness requirements to shield from nuclear bomb radiation.
Different material thickness requirements to shield from nuclear bomb radiation.

What is the protection for of 48 inches of earth and 12 inches of concrete from fallout?
For the earth cover protection, go to the Earth-Gamma column. The nearest values to “48 inches” are 44 and 49.5. Round down to 44 as this is a more conservative. 44 inches of earth has an HVL of 8.

For the concrete cover protection, go to the Concrete-Gamma column. The nearest values to “12 inches” are 11.7 and 15.6. Round down to 15.6 inches of concrete cover. 11.7 inches of concrete has an HVL of 3.

Combine the 8 earth and 3 concrete HVL’s. An HVL of 11 has a PF of 2,048. The protection of 44 earth inches and 11.7 concrete inches is 1/2048th of the unprotected dose

The source of neutron radiation comes directly from the fireball and has a life of less than sixty seconds. During this time period, neutron radiation induces extremely high levels of radiation doses. The source of gamma radiation is the fireball and fallout. (See Figure 4.1.) The quantity of fallout varies depending on the type of burst, size of weapon, type of soil at ground zero, distance from ground zero, weather, and so on. However, to allow some general reference point as to the quantity of fallout, an analogy can be made with respect to common lawn fertilizer. A typical 40 bag of fertilizer would be spread over an area of approximately 5000 ft2. The quantity of fallout deposited directly downwind close to ground zero would be analogous to spreading this bag of fertilizer over an area of approximately 1200 ft2 or an area measuring 35 ft. x 35 ft.

A barrier of earth, concrete, lead, or steel is placed between the source of radiation and the protected target. Each material has a given ability to reduce the quantity of radiation which passes through it. This ability to shield from ionizing radiation is based primarily on the density and moisture content of the material.

Geometry shielding is a method where a mechanical design reduces the radiation entering the shelter. Radiation does not travel in a perfectly straight line and does, in fact, bend or scatter around corners. As it does, it is attenuated (reduced). This is the reason for 90° angled entranceways or offset entranceways for blast shelters. Another aspect of geometry shielding is the Inverse Square Law. Radiation decreases in intensity with distance. The further from the radiation source, the lower the radiation intensity or dose will be. However, the reduction is very small. At one hundred feet away from the fallout, the reduction in radiation is approximately one-half. At six hundred feet from the fallout radiation source, the reduction is approximately one-tenth.1 Taking refuge in the second story of a house to gain distance from the fallout on the ground will provide little if any reduction in radiation dose. In fact, the dose may be greater due to the presence of fallout on the roof of the house.

Nuclear Weapons Effects

Nuclear Explosion Reactions for Different Bomb Sizes

 

Potential Cancer Deaths Lifetime Percent

Estimations of “Potential Cancer Deaths Lifetime Percent” due to radiation exposure are based on the Federal Emergency Management Agency “Nuclear Attack Planning Base: 1990 Final Project Report (NAPB-90),” page 25. For the dose listed, one-third is assumed to be received during the first week. The remaining two-thirds radiation dose is assumed to be received after the first week over the long term.

Current Cancer Death Lifetime Percent

The current probability that a person will contract a fatal cancer over a seventy-five-year lifetime is 16 to 20 percent depending on sex. This is known as the “current cancer death lifetime percent.” The value of 18 percent shown in the table was chosen as a median level to allow a fixed point of reference. The “potential cancer death lifetime percent” includes the current cancer death lifetime percent of 18 percent. The table is based on a potential increase in cancer death rates of 1.25 percent for the first one hundred rems and 3 percent for radiation doses over one hundred rems. 0-100 REMs = (1.25% * REMs/100) + 18% 100+ REMs = (3% * REMs/100) + 18%

Potential Cancer Deaths Rate

The “potential cancer deaths rate”/100,000 is based on the American Cancer Society “Facts and Figures for 1987,” page 29, for both males and females during 1981 to 1983. The current rate of cancer deaths is approximately 352/100,000 per year. The increased rate includes the current rate in proportion to the “potential cancer deaths lifetime percent.”

The Modern Shelterist

It cannot be overemphasized that these potential cancer rates are based on the victims of the Hiroshima and Nagasaki bombings who met the following criteria:

  • Were malnourished and already suffering from many diseases during a critical wartime period where food, medical supplies, and other necessities were in short supply
  • Had already been exposed to the effects of blast and heat and were consequently in shock, with few facilities and medical help to allow complete recovery
  • Had absolutely no knowledge about radiation. They were unaware of the danger of fallout from the bomb casing. Consequently, many people suffered beta burns from the fallout being in direct contact with their skin.
  • Were exposed to not only gamma radiation but neutron radiation, which is much more damaging to the human body
  • Ingested the fallout by inhalation and contaminated food, which is the most damaging to the human body

An educated and prepared shelterist is able to avoid the effects that the Hiroshima and Nagasaki victims suffered. It must be noted that these five effects may act synergistically; that is, these effects may amplify each other. Thus, these potential cancer death rates may be excessively high, but this allows the shelterist to prepare for the worst. For example, if a person receives ten rems starting immediately after detonation, 3.33 rems are assumed to be received during the first week. Of this ten rems, 6.66 rems are assumed to be received after the first week. This would increase the percentage of contracting a fatal cancer from the current level of 18 percent to 18.1 percent.

McCarthy, Walton W. Appendix A. Principles of Protection: U.S. Handbook of NBC Weapon Fundamentals and Shelter Engineering Design Standards. Dallas: Brown Group, 2013. 662. Print.

SHORT-TERM EFFECTS FROM ACUTE RADIATION DOSES
Short-Term Effects From Acute Doses* Long-Term Effects
Dose REMS Potential Cancer Deaths Rate/100,000 Potential Cancer Deaths Lifetime %
0.01 Dental X-Ray (Whole Mouth) 352 18.0
0.4 Lumbar Spine X-Ray 352 18.0
0.5 Mammography X-Ray 352 18.0
1.0 Barium Enema 352 18.0
10 20 30 The human body can tolerate doses in this range on a consistent basis without any changes in blood formation. 355 357 359 18.1 18.3 18.4
40 50 No visible effects. There are changes in the blood that the body can adequately deal with. Regular activities may continue. 362 364 18.5 18.6
60 70 80 90 100 120 140 160 180 Brief periods of nausea on day of exposure. Up to 50 percent may experience radiation sickness (nausea); 5 percent may require medical attention. No deaths expected. Radiation therapy typically uses 180 to 200 rems per day for a period of one to six weeks. Some cases require localized doses while others require organ doses. 367 369 372 374 376 422 434 446 458 18.8 18.9 19.0 19.1 19.3 21.6 22.2 22.8 23.4
200 250 300 350 400 450 Most will require medical attention because of serious radiation sickness; 50 percent deaths within two to four weeks. 469 499 528 557 587 616 24.0 25.5 27.0 28.5 30.0 31.5
460 500 550 600 Serious radiation sickness; all require medical attention. Death for more than 50 percent within one to three weeks. 622 645 675 704 31.8 33.0 34.5 36.0
600-1,000 Death for 50 percent within one to three weeks.
1,000-5,000 100 percent deaths in two to fourteen days.
5,000+ 100 percent deaths in zero to two days.
*Doses received within a twenty-four-hour period.

McCarthy, Walton W. Appendix A. Principles of Protection: U.S. Handbook of NBC Weapon Fundamentals and Shelter Engineering Design Standards. Dallas: Brown Group, 2013. 662. Print.

Nuclear Weapons Effects: 1 MT Surface Burst with 15 MPH Wind
1-MT SURFACE BURST 15 MPH WIND Miles Downwind of Ground Zero
Weapon Effects Units MSD .5 .6 .7 .8 .9 1 2 3 4 5 10 50 100
Thermal Burns degree FB FB FB FB FB FB 3 3 3 3 3
Thermal Energy Skin cal/cm2 3,500 3,500 2,300 1,600 1,200 900 700 140 52 28 16 3
Maximum burst Wind mph 2,000 2,000 1,700 1,500 1,400 1,100 800 260 150 100 70 22
Maximum Overpress psi 200 200 130 85 70 48 38 9 5 3 2 1
Overpressure Arrival seconds 0 0 0 0 0 0 1 5 8 14 16 45
Overpressure Duration seconds 1 1 1 1 1 1 1 2 3 4 5 45
Max. Dynamic Pressure psi 350 350 190 130 100 58 30 2 <1 <1 <1
Peak Vert. Displacement inches 11.7 11.7 8.8 6.6 5.8 4.5 3.9 1.4 0.8 0.5
Peak Horiz. Displacement inches 3.9 3.9 2.9 2.2 1.9 1.5 1.3 0.5 0.3 0.2
Total Neutron Radiation rems 1,000,000 1,000,000 500,000 210,000 130,000 56,000 32,000 40
Total Fallout Gamma rems 12,988 12,988 12,988 12,988 12,988 12,988 12,988 12,988 12,988 12,988 12,509 9,137 1,073 277
Total Initial Gamma rems 250,000 120,000 80,000 50,000 20,000 10,000 80 3
Fallout Arrival Time hours 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 2.9 6.3
Fallout Radiation Doses
Week One rems/day 1,692 1,692 1,692 1,692 1,692 1,692 1,692 1,692 1,692 1,692 1,665 1,192 131 32
Week Two rems/day 52 52 52 52 52 52 52 52 52 52 51 37 7 2
Week Three rems/day 35 35 35 35 35 35 35 35 35 35 34 24 5 2
Week Four rems/day 25 25 25 25 25 25 25 25 25 25 25 18 3 1
Month Two rems/day 3 3 3 3 3 3 3 3 3 3 3 2 0.5 0.2
Month Three rems/day 3 3 3 3 3 3 3 3 3 3 3 2 0.4 0.1
Month Four rems/day 2 2 2 2 2 2 2 2 2 2 2 2 0.3 0.1
Month Five rems/day 2 2 2 2 2 2 2 2 2 2 2 1 0.3 0.1
Month Six rems/day 2 2 2 2 2 2 2 2 2 2 2 1 0.2 0.1
Crater Radius = 370-660 ft (dry, hard rock-soft, wet soil)
Crater Depth = 190-260 ft (dry, hard rock-soft, wet soil)
Maximum Cloud Radius = 10.0 miles
Maximum Cloud Height = 13.0 miles
Maximum Fireball Radius (FB) = 0.9 miles
Minimum Survival Distance (MSD) = 0.5 miles
=No measurable effect

McCarthy, Walton W. Appendix A. Principles of Protection: U.S. Handbook of NBC Weapon Fundamentals and Shelter Engineering Design Standards. Dallas: Brown Group, 2013. 663. Print.

Nuclear Weapons Effects: 500 KT Surface Burst with 15 MPH Wind
500-KT SURFACE BURST 15 MPH WIND Miles Downwind of Ground Zero
Weapon Effects Units MSD .5 .6 .7 .8 .9 1 2 3 4 5 10 50 100
Thermal Burns degree FB FB FB FB 3 3 3 3 3 3 3
Thermal Energy Skin cal/cm2 3,250 2,000 1,300 900 600 490 360 70 27 13 8
Maximum Blast Wind mph 2,000 1,600 1,400 1,200 800 600 550 220 105 70 48
Maximum Overpress psi 200 120 70 50 36 28 23 7 3 2 1
Overpressure Arrival seconds 0 <1 <1 <1 1 1 2 5 10 14 20
Overpressure Duration seconds <1 <1 <1 1 1 1 1 1 2 3 4
Max. Dynamic Pressure psi 300 170 110 60 25 14 10 1 <1
Peak Vert. Displacement inches 9.8 6.9 4.7 3.7 3.0 2.5 2.1 0.8
Peak Horiz. Displacement inches 3.3 2.3 1.6 1.3 1.0 0.8 0.7 0.3
Total Neutron Radiation rems 1,000,000 600,000 220,000 110,000 46,000 23,000 14,000 40
Total Fallout Gamma rems 11,854 11,854 11,854 11,854 11,854 11,854 11,854 11,854 11,854 11,154 10,387 7,035 771 210
Total Initial Gamma rems 125,000 125,000 60,000 40,000 20,000 9,000 4,000 10 1
Fallout Arrival Time hours 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 3 6
Fallout Radiation Doses
Week One rems/day 1,541 1,541 1,541 1,541 1,541 1,541 1,541 1,541 1,541 1,446 1,351 914 95 24
Week Two rems/day 47 47 47 47 47 47 47 47 47 44 42 28 5 2
Week Three rems/day 31 31 31 31 31 31 31 31 31 30 28 19 3 1
Week Four rems/day 23 23 23 23 23 23 23 23 23 22 20 14 2 0.8
Month Two rems/day 3 3 3 3 3 3 3 3 3 3 3 2 0.3 0.1
Month Three rems/day 3 3 3 3 3 3 3 3 3 3 2 2 0.3 0.1
Month Four rems/day 2 2 2 2 2 2 2 2 2 2 2 1 0.2 0.1
Month Five rems/day 2 2 2 2 2 2 2 2 2 2 2 1 0.2 0.1
Month Six rems/day 2 2 2 2 2 2 2 2 2 2 1 1 0.2 0.1
Crater Radius = 317-528 ft (dry, hard rock and soft, wet soil)
Crater Depth = 148-206 ft (dry, hard rock and soft, wet soil)
Maximum Cloud Radius = 7.4 miles
Maximum Cloud Height = 11 miles
Maximum Fireball Radius (FB) = 0.7 miles
Minimum Survival Distance (MSD) = 0.4 miles
= No Measurable Effect
Note: Decimal places are used to show progression of effects and are not intended to indicate fractional accuracy.

McCarthy, Walton W. Appendix A. Principles of Protection: U.S. Handbook of NBC Weapon Fundamentals and Shelter Engineering Design Standards. Dallas: Brown Group, 2013. 664. Print.

Nuclear Weapons Effects: 200 KT Surface Burst with 15 MPH Wind
200-KT SURFACE BURST 15 MPH WIND Miles Downwind of Ground Zero
Weapon Effects Units MSD .5 .6 .7 .8 .9 1 2 3 4 5 10 50 100
Thermal Burns degree FB FB 3 3 3 3 3 3 3 3 2
Thermal Energy Skin cal/cm2 1,500 900 560 400 300 220 180 35 14 7 4
Maximum Blast Wind mph 2,000 1,200 750 600 480 400 340 120 65 40 28
Maximum Overpress psi 200 52 35 25 20 15 12 4 2 1
Overpressure Arrival seconds 0 <1 1 1 1 2 2 5 10 16 20
Overpressure Duration seconds <1 <1 <1 1 1 1 1 2 3 3 3
Max. Dynamic Pressure psi 300 65 25 12 7 5 3
Peak Vert. Displacement inches 7.9 2.9 2.2 1.6 1.3 1.0 0.8
Peak Horiz. Displacement inches 2.6 1.0 0.7 0.5 0.4 0.3 0.3
Total Neutron Radiation rems 1,000,000 170,000 76,000 35,000 20,000 10,000 4,500 10
Total Fallout Gamma rems 10,464 10,464 10,464 10,464 10,464 10,464 10,464 10,464 9,925 8,938 7,854 776 507 138
Total Initial Gamma rems 50,000 50,000 20,000 9,000 4,000 2,500 1,000 3
Fallout Arrival Time hours 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 3 6
Fallout Radiation Doses
Week One rems/day 1,362 1,362 1,362 1,362 1,362 1,362 1,362 1,362 1,290 1,157 1,024 643 62 16
Week Two rems/day 42 42 42 42 42 42 42 42 40 36 32 20 3 1
Week Three rems/day 28 28 28 28 28 28 28 28 26 24 21 13 2 0.8
Week Four rems/day 20 20 20 20 20 20 20 20 19 17 15 10 2 0.6
Month Two rems/day 3 3 3 3 3 3 3 3 3 3 2 1 0.2 0.1
Month Three rems/day 2 2 2 2 2 2 2 2 2 2 2 1 0.2 0.1
Month Four rems/day 2 2 2 2 2 2 2 2 2 2 1 0.9 0.2 0.1
Month Five rems/day 2 2 2 2 2 2 2 2 2 2 1 0.8 0.1
Month Six rems/day 1 1 1 1 1 1 1 1 1 1 1 0.7 0.1
Crater Radius = 238-396 ft (dry, hard rock and soft, wet soil)
Crater Depth = 106-159 ft (dry, hard rock and soft, wet soil)
Maximum Cloud Radius = 5 miles
Maximum Cloud Height = 9 miles
Maximum Fireball Radius (FB) = 0.5 miles
Minimum Survival Distance (MSD) = 0.3 miles
= No Measurable Effect
Note: Decimal places are used to show progression of effects and are not intended to indicate fractional accuracy.

McCarthy, Walton W. Appendix A. Principles of Protection: U.S. Handbook of NBC Weapon Fundamentals and Shelter Engineering Design Standards. Dallas: Brown Group, 2013. 665. Print.

Nuclear Weapons Effects: 100 KT Surface Burst with 15 MPH Wind
100-KT SURFACE BURST 15 MPH WIND Miles Downwind of Ground Zero
Weapon Effects Units MSD .5 .6 .7 .8 .9 1 2 3 4 5 10 50 100
Thermal Burns degree FB 3 3 3 3 3 3 3 3 3 1
Thermal Energy Skin cal/cm2 2,500 500 350 230 180 130 110 22 9 7 3
Maximum Blast Wind mph 2,000 700 500 400 340 280 240 85
Maximum Overpress psi 200 30 21 15 12 10 8 2
Overpressure Arrival seconds <1 <1 <1 1 1 2 2 8
Overpressure Duration seconds <1 <1 <1 1 1 1 1 2
Max. Dynamic Pressure psi 300 20 9 5 3 2 1 <1
Peak Vert. Displacement inches 6.9 1.5 1.0 0.7 0.6 0.4 0.3
Peak Horiz. Displacement inches 2.3 0.5 0.4 0.2 0.2 0.1 0.1
Total Neutron Radiation rems 1,000,000 80,000 25,000 15,000 7,000 4,000 1,600
Total Fallout Gamma rems 9,554 9,554 9,554 9,554 9,554 9,554 9,554 9,064 8,507 7,478 6,379 3,753 375 100
Total Initial Gamma rems 25,000 25,000 10,000 4,500 2,000 1,200 500 2
Fallout Arrival Time hours 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 1 3 6
Fallout Radiation Doses
Week One rems/day 1,240 1,240 1,240 1,240 1,240 1,240 1,240 1,174 1,107 969 831 493 45 12
Week Two rems/day 38 38 38 38 38 38 38 36 34 30 26 15 3 0.9
Week Three rems/day 25 25 25 25 25 25 25 24 22 20 17 10 2 0.6
Week Four rems/day 19 19 19 19 19 19 19 18 17 15 12 7 1 0.4
Month Two rems/day 3 3 3 3 3 3 3 3 2 2 2 1 0.2 0.1
Month Three rems/day 2 2 2 2 2 2 2 2 2 2 1 0.8 0.1
Month Four rems/day 2 2 2 2 2 2 2 2 2 2 1 0.7 0.1
Month Five rems/day 2 2 2 2 2 2 2 2 1 1 1 0.6 0.1
Month Six rems/day 1 1 1 1 1 1 1 1 1 1 0.9 0.5 0.1
Crater Radius = 211-317 ft (dry, hard rock and soft, wet soil)
Crater Depth = 90-127 ft (dry,hard rock and soft, wet soil)
Maximum Cloud Radius = 3.7 miles
Maximum Cloud Height = 7 miles
Maximum Fireball Radius (FB) = 0.35 miles
Minimum Survival Distance (MSD) = 0.24 miles
= No Measurable Effect
Note: Decimal places are used to show progression of effects and are not intended to indicate fractional accuracy.

McCarthy, Walton W. Appendix A. Principles of Protection: U.S. Handbook of NBC Weapon Fundamentals and Shelter Engineering Design Standards. Dallas: Brown Group, 2013. 666. Print.

Nuclear Weapons Effects: 50 KT Surface Burst with 15 MPH Wind
50-KT SURFACE BURST 15 MPH WIND Miles Downwind of Ground Zero
Weapon Effects Units MSD .5 .6 .7 .8 .9 1 2 3 4 5 10 50 100
Thermal Burns degree FB FB FB FB 3 3 3 3 3 3 3
Thermal Energy Skin cal/cm2 2,400 250 170 120 90 70 50 10 4 2 1
Maximum Blast Wind mph 2,000 470 350 290 240 210 170 60 30
Maximum Overpress psi 200 19 13 10 8 7 6 2 1
Overpressure Arrival seconds <1 <1 2 2 2 2 2 6 10
Overpressure Duration seconds <1 <1 <1 <1 <1 1 1 2 2
Max. Dynamic Pressure psi 325 7 4 2 2 1 1
Peak Vert. Displacement inches 6.0 0.7 0.4
Peak Horiz. Displacement inches 2.0 0.2 0.1
Total Neutron Radiation rems 1,000,000 30,000 17,000 7,000 3,000 2,000 1,000
Total Fallout Gamma rems 8,645 8,645 8,645 8,645 8,645 8,645 8,645 7,980 7,301 6,210 5,168 2,912 280 73
Total Initial Gamma rems 12,000 12,000 5,000 2,000 1,000 500 250 7
Fallout Arrival Time hours 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 3 6
Fallout Radiation Doses
Week One rems/day 1,130 1,130 1,130 1,130 1,130 1,130 1,130 1,041 951 813 674 378 33 9
Week Two rems/day 35 35 35 35 35 35 35 32 29 25 21 12 2 0.7
Week Three rems/day 23 23 23 23 23 23 23 21 19 17 14 8 1 0.4
Week Four rems/day 17 17 17 17 17 17 17 16 14 12 10 6 0.9 0.3
Month Two rems/day 2 2 2 2 2 2 2 2 2 1 1 0.8 0.1
Month Three rems/day 2 2 2 2 2 2 2 2 2 1 1 0.6 0.1
Month Four rems/day 1 1 1 1 1 1 1 1 1 1 1 0.5 0.1
Month Five rems/day 1 1 1 1 1 1 1 1 1 0.9 0.8 0.5 0.1
Month Six rems/day 1 1 1 1 1 1 1 1 1 0.8 0.7 0.4 0.1
Crater Radius = 185-317 ft (dry, hard rock and soft, wet soil)
Crater Depth = 79-132 ft (dry, hard rock and soft, wet soil)
Maximum Cloud Radius = 2.8 miles
Maximum Cloud Height = 7.5 miles
Maximum Fireball Radius (FB) = 0.4 miles
Minimum Survival Distance (MSD) = 0.19 miles
= No Measurable Effect
Note: Decimal places are used to show progression of effects and are not intended to indicate fractional accuracy.

McCarthy, Walton W. Appendix A. Principles of Protection: U.S. Handbook of NBC Weapon Fundamentals and Shelter Engineering Design Standards. Dallas: Brown Group, 2013. 667. Print.

LEGEND FOR WEAPON EFFECTS TABLES
Thermal Burns Degree of burn an unprotected person would receive.1
Thermal Energy-Skin The heat, in calories per square centimeter (Cal/cm2) of skin, that unprotected, medium-dark human skin would receive.2
Maximum Blast Wind The speed, in miles per hour, at which the blast wave travels.3
Maximum Overpressure The intensity, in pounds per square inch, of crushing overpressure.4
Overpressure Arrival The time, in seconds, from detonation to reach various distances from ground zero.5
Overpressure Duration The length of time, in seconds, the overpressure will be in effect.6
Maximum Dynamic Pressure The drag force, in pounds per square inch, on objects at or above the ground surface.7
Peak Vert. Displacement The peak surface and residual vertical displacement based on a seismic velocity of 1,414 fps.8
Peak Horiz. Displacement The peak horizontal displacement = one-third of the peak vertical displacement.9
Total Neutron Radiation The total dose of neutron radiation in rems. This dose is delivered within sixty seconds of detonation.10
Total Fallout Gamma The total dose of gamma radiation in rems from fallout using the DELFIC model.11
Total Initial Gamma The total dose of initial gamma radiation.12
Fallout Arrival Time The time, in hours, it takes for fallout to arrive at various distances from ground zero with a fifteen-mph wind.13
Fallout Radiation Doses The dose of radiation, in rems/twenty-four hr day, during various periods (week one, week two, month two, etc.) following detonation that an unprotected person would receive. These doses are based on no precipitation of any kind. Rain would allow the radioactive fallout particles to leach into the soil and reduce these doses.14
Crater Radius15
Crater Depth16
Maximum Cloud Radius17
Maximum Cloud Height18
Maximum Fireball Radius (FB)19
Minimum Survival Distance (MSD)20

Notes:

  • Based on weapons which are 50/50 fission/fusion.
  • Based on height of burst, optimizing weapon effects, and properly detonating.
  • Based on ideal surfaces (flat terrain; no trees; clear atmosphere at sea level; with no wind and no rain, snow, or fog.)
  • Radiation doses would be reduced by half if twelve hours per day are spent in adequate shelter.
  • All effects, except for fallout radiation doses, are not related to being upwind or downwind of ground zero.
  • All values are rounded to the nearest whole number.
  • One week equals 168 hours; one month equals four weeks or 672 hours.

NOTES

1 US Department of Defense and Energy Research and Development Administration. Effects of Nuclear Weapons. Compiled by Samuel Glasstone and P. J. Dolan. Washington, DC. 1977. 305-312. These values are based on Figure 12.64 on page 564 using medium skin. 2 US Department of Defense and Energy Research and Development Administration. Effects of Nuclear Weapons. Compiled by Samuel Glasstone and P. J. Dolan. Washington, DC. 1977. Calculated on the Nuclear Bomb Effect Computer. 3 US Department of Defense and Energy Research and Development Administration. Effects of Nuclear Weapons. Compiled by Samuel Glasstone and P. J. Dolan. Washington, DC. 1977. Calculated on the Nuclear Bomb Effect Computer. 4 US Department of Defense and Energy Research and Development Administration. Effects of Nuclear Weapons. Compiled by Samuel Glasstone and P. J. Dolan. Washington, DC. 1977. Calculated on the Nuclear Bomb Effect Computer. 5 US Department of Defense and Energy Research and Development Administration. Effects of Nuclear Weapons. Compiled by Samuel Glasstone and P. J. Dolan. Washington, DC. 1977. Calculated on the Nuclear Bomb Effect Computer. 6 US Department of Defense and Energy Research and Development Administration. Effects of Nuclear Weapons. Compiled by Samuel Glasstone and P. J. Dolan. Washington, DC. 1977. Calculated on the Nuclear Bomb Effect Computer. 7 US Department of Defense and Energy Research and Development Administration. Effects of Nuclear Weapons. Compiled by Samuel Glasstone and P. J. Dolan. Washington, DC. 1977. Calculated on the Nuclear Bomb Effect Computer. 8 Federal Emergency Management Agency. Protective Construction Nuclear Blast Resistant Design, TR-20. Vol. 4. Washington, DC. March 1985. Chapter 6, 6-16. 9 Federal Emergency Management Agency. Protective Construction Nuclear Blast Resistant Desing TR-20. Vol. 4. Washington, DC. March 1985. Chapter 6, 6-16. 10 US Department of Defense and Energy Research and Development Administration. Effects of Nuclear Weapons. Compiled by Samuel Glasstone and P. J. Dolan. Washington, DC. 1977. These values were calculated on the Nuclear Bomb Effect Computer and graphed as smooth curves to prevent errors from logarithmic increments. 11 These values were determined by Edward York, using the DNA Weapon Effects Rule WEG-1, 257-261. Prepared for the Defense Nuclear Agency by Horizons Technology Inc. under contract DNA 001 83-C-0004. 12 These values were developed by Dr. Joseph McGahan of the Scientific Applications International Corporation. These values are not theoretical. They were derived from the DELFIC model, which is based on actual radioactivity measurements made on site of the nuclear surface burst tests conducted in the United States prior to the Nuclear Test Ban Treaty of 1964. 13 US Department of Defense and Energy Research and Development Administration. Effects of Nuclear Weapons. Compiled by Samuel Glasstone and P. J. Dolan. Washington, DC. 1977. These values were determined based on section 9.97 on page 430 for a wind speed of fifteen mph. 14 These values were developed by Dr. Joseph McGahan of the Scientific Applications International Corporation. These values are not theoretical. They were derived from the DELFIC model, which is based on actual radioactivity measurements made on site of the nuclear surface burst tests conducted in the United States prior to the Nuclear Test Ban Treaty of 1964. 15 US Department of Defense and Energy Research and Development Administration. Effects of Nuclear Weapons. Compiled by Samuel Glasstone and P. J. Dolan. Washington, DC. 1977. Calculated on the Nuclear Bomb Effect Computer. 16 US Department of Defense and Energy Research and Development Administration. Effects of Nuclear Weapons. Compiled by Samuel Glasstone and P. J. Dolan. Washington, DC. 1977. Calculated on the Nuclear Bomb Effect Computer. 17 These values were developed by Dr. Joseph McGahan of the Scientific Applications International Corporation. They were derived from the DELFIC model which is based on measurements made on site of the nuclear surface burst tests conducted in the United States prior to the Nuclear Test Ban Treaty of 1964. 18 US Department of Defense and Energy Research and Development Administration. Effects of Nuclear Weapons. Compiled by Samuel Glasstone and P. J. Dolan. Washington, DC. 1977. Cloud heights based on Figure 2.16 on page 34. 19 US Department of Defense and Energy Research and Development Administration. Effects of Nuclear Weapons. Compiled by Samuel Glasstone and P. J. Dolan. Washington, DC. 1977. Calculated on the Nuclear Bomb Effect Computer. 20 US Department of Defense and Energy Research and Development Administration. Effects of Nuclear Weapons. Compiled by Samuel Glasstone and P. J. Dolan. Washington, DC. 1977. Based on 200 psi and calculated on the Nuclear Bomb Effect Computer. It is possible to survive much closer; however, special materials and engineering must be used.

McCarthy, Walton W. Appendix A. Principles of Protection: U.S. Handbook of NBC Weapon Fundamentals and Shelter Engineering Design Standards. Dallas: Brown Group, 2013. 670. Print.

Radiation Doses – Overhead

GAMMA AND NEUTRON RADIATION DOSES COMBINED IN REMS INSIDE A SHELTER BASED ON EARTH COVER 100 KT SURFACE BURST

Shielding: Any material or obstruction that absorbs or attenuates radiation and thus tends to protect personnel or materials from the effects of a nuclear explosion. A moderately thick layer of any opaque material will provide satisfactory shielding from thermal radiation, but a considerable thickness of high-density material may be needed for nuclear radiation shielding, especially for neutron radiation shielding. NORAD S-Series fallout shelters are rated at 10 psi with 72 inches of earth over the crown of the shelter ceiling.

How to Read this Table

Dist. GZ: Distance from Ground Zero MSD: Minimum Survival Distance Example: Referring to the table, a shelter located in the 8 psi range or one mile downwind of a one-hundred-KT surface burst weapon would be exposed to a gamma radiation dose on the ground of 10,054 rems. A shelter at this location with thirty-six inches of earth cover (thirty-three inches is the closest conservative number) would result in a radiation dose of 170 rems to people inside the shelter. People receiving this dose would suffer radiation sickness within two to three hours. Most people would survive if they are in good health at the time. The established maximum radiation dose inside an underground shelter is twenty-five rems from all radiation sources for the first thirty days following the detonation.

GAMMA AND NEUTRON RADIATION DOSES COMBINED IN REMS INSIDE A SHELTER BASED ON EARTH COVER
100 KT SURFACE BURST
Dist. GZ MSD 0.5 MI 0.6 MI 0.7 MI 0.8 MI 0.9 MI 1 MI 10 MI 25 MI 50 MI 100 MI
Overpressure psi 200 30 21 15 12 10 8 0 0 0 0
Initial Gamma rems 25,000 25,000 10,000 4,500 2,000 1,200 500 0 0 0 0
Fallout Gamma rems 9,554 9,554 9,554 9,554 9,554 9,554 9,554 5,800 3,800 375 100
Neutron rems 1,000,000 80,000 25,000 15,000 7,000 4,000 1,600 0 0 0 0
Earth-inch                      
5.5 517,277 57,277 22,277 14,527 9,277 7,377 5,827 2,900 1,900 188 50
11.0 258,639 28,639 11,139 7,264 4,639 3,689 2,914 1,450 950 94 25
16.5 129,319 14,319 5,569 3,632 2,319 1,844 1,457 725 475 47 13
22.0 64,660 7,160 2,785 1,816 1,160 922 728 363 238 23 6
27.5 32,330 3,580 1,392 908 580 461 364 181 119 12 3
33.0 8,353 1,165 501 337 236 199 170 91 59 6 2
38.5 4,176 583 251 169 117 100 85 45 30 3 1
44.0 2,088 291 125 84 59 50 42 23 15 1 0
49.5 1,044 145 62 42 30 25 22 11 7 1 0
55.0 522 73 31 21 14 13 11 6 4 0 0
60.5 261 37 16 11 8 6 5 3 2 0 0
66.0 69 18 7 5 3 3 2 1 1 0 0
71.5 35 6 3 2 1 1 1 1 0 0 0
77.0 17 3 1 1 1 1 1 0 0 0 0
82.5 9 2 1 0 0 0 0 0 0 0 0
88.0 5 1 0 0 0 0 0 0 0 0 0
93.5 2 0 0 0 0 0 0 0 0 0 0
99.0 0 0 0 0 0 0 0 0 0 0 0
104.5 0 0 0 0 0 0 0 0 0 0 0
110.0 0 0 0 0 0 0 0 0 0 0 0
115.5 0 0 0 0 0 0 0 0 0 0 0
121.0 0 0 0 0 0 0 0 0 0 0 0
PRINCIPLES OF PROTECTION, The US Handbook of NBC Weapons Fundamentals and Shelter Engineering Design Standards, 6th edition, 2013, Walton McCarthy M.E. Brown Books.
Effects Rems
50% Lethal 200-450
radiation sickness 50-200
blood effect 25-50
safe 0-25

Entranceway Radiation Calculator

Air burst and surface burst cast radiation on the shelter entranceway NORAD Provides Safety Performance Data Documenting How Its Blast Shelters Protect Individuals from Radiation

  • High radiation levels from a nuclear weapon can enter the shelter through the entranceway.
  • It is the most misunderstood area of radiation shielding.
  • Good entranceway design will not allow more than 5 rems to enter the shelter at Point Z.
  • Heavy steel hatches are considered invisible to radiation unless the hatch and tunnel connecting to the hatch is 1.125 inches thick or one HVL (Half Value Layer).
  • See Radiation Shielding Materials.
  • The larger the entranceway diameter tunnel, the more radiation is allowed to enter.
  • Placing radiation shielding barriers in the entranceway is not efficient since it has to be so thick and heavy and creates a safety hazard.
  • POP 13.01 does not allow blocks, bricks, or plates to be used.
  • The farther the hatch is away from the connection to the shelter the less radiation enters are Point Z.
  • Neutron radiation has a lifespan of not more than 60 seconds.
  • Any shelter in the neutron radiation area will suffer ground shock which will alert the shelterists to walk away from Point Z for 60 seconds until the neutron radiation phase passes.
  • After this time gamma radiation is the main threat and will last 30 days.
  • After 30 days 99% of the all the radiation produced will have fallen and decayed.
  • See Radiation Tables

Radiation Shielding 30 Inch Diameter Entranceway

All NORAD shelters have performance data on radiation that enters the shelter entranceway based on weapon size and distance from Ground Zero.

Shelter Design Radiation Dose: 1-20 psi
Fallout 12,000 rems
Initial Gamma 3,250 rems
Neutron 9,000 rems
Horizontal Distance (Ft)
Vertical Depth 0.0 2.5 4 6 8 10 12 14 16
2.5(Ft) 200 70 39 18 8 4 2
4 106 37 21 9 4 2 1
6 57 20 11 5 2 1
8 35 12 7 3 1 1
10 24 8 5 2 1 1
12 17 6 3 2 1 1
14 13 5 3 1 1 1
16 10 4 2 1 1 1
Shelter Design Radiation Dose: 21-40 psi
Fallout 12,000 rems
Initial Gamma 20,750 rems
Neutron 60,000 rems
Horizontal Distance (Ft)
Vertical Depth 0.0 2.5 4 6 8 10 12 14 16
2.5(Ft) 1265 461 254 115 52 24 11 5 2
4 671 244 135 61 28 13 6 3 1
6 359 131 72 33 15 7 3 1
8 222 81 45 20 9 4 2
10 151 55 30 14 6 3 1
12 109 40 22 10 5 2 1
14 82 30 17 8 3 2 1
16 65 24 13 6 3 1 1
Shelter Design Radiation Dose: 41-60 psi
Fallout 12,000 rems
Initial Gamma 45,000 rems
Neutron 160,000 rems
Horizontal Distance Feet
Vertical Depth 0.0 2.5 4 6 8 10 12 14 16
2.5 (Ft) 3,343 1,226 675 306 139 63 29 13 6
4 1,771 650 358 162 74 33 15 7 3
6 947 348 191 87 39 18 8 4 2
8 587 215 119 54 24 11 5 2 1
10 398 146 81 37 17 8 3 2 1
12 288 106 59 26 12 5 3 1 1
14 218 80 44 20 9 4 2 1
16 170 63 35 16 7 3 2 1
Shelter Design Radiation Dose: 61-80 psi
Fallout 12,000 rems
Initial Gamma 72,500 rems
Neutron 300,000 rems
Horizontal Distance (Ft)
Vertical Depth 0.0 2.5 4 6 8 10 12 14 16
2.5(Ft) 6245 2298 1257 574 260 118 54 24 11
4 3301 1217 671 304 138 63 28 13 6
6 1769 651 359 163 74 33 15 7 3
8 1096 403 222 101 46 21 9 4 2
10 744 274 151 68 31 14 6 3 2
12 538 198 109 49 22 10 5 2 1
14 407 150 83 37 17 8 4 2 1
16 318 117 65 29 13 6 3 1

REFERENCES – Cited U.S. Department of Defense and Energy Research and Development Administration, EFFECTS of NUCLEAR WEAPONS, Compiled by Samuel Glasstone and P.J. Dolan, Washington, D.C., 1977, p. 455 Figure 9.157. U.S. Department of Defense and Energy Research and Development Administration, EFFECTS of NUCLEAR WEAPONS, Compiled by Samuel Glasstone and P.J. Dolan, Washington, D.C., 1977, p. 337. See appendix B. This formula was developed specifically for personal blast shelters by Dr. Arthur B. Chilton. In developing this formula, he used the following books as references. Numbers were rounded using normal rounding procedures. Diaz, J. and A.B. Chilton, MODELING RELATIONSHIPS for RADIATION TRANSPORT within DUCTS and OTHER CAVITIES in SHIELDS, Nucl. Sci., and Eng. 35,283, 1969. Jaeger, R.G. ed., ENGINEERING COMPENDIUM on RADIATION SHIELDING FUNDAMENTALS and METHODS, New York, Springer- Verlag, 1968. Kimel, H.R.ed., RADIATION SHIELDING ANALYSIS and DESIGN PRINCIPLES as APPLIED to NUCLEAR DEFENSE PLANNING, TR- 40, OCD/KSU, Report Supt. of Documents, U.S. Government Printing Office, Washington, D.C., 1966. Maeker,R.E. and F.J. Muckenthaler, NEUTRON FLUXES in CONCRETE DUCTS ARISING from INCIDENT EPICADMIUM NEUTRONS: CALCULATIONS and EXPERIMENTS, Nucl. Sci., and Eng. 35,283, 1969. NEWMARK, N.M., DESIGN of OPENINGS for BURIED SHELTERS, Contract Report 2-67, U.S. Army Engineer Waterways Experiment Station, July 1963. Ritchie, R.H. and G.S. Hurst, “Penetration of Weapons Radiation: Application to the Hiroshima-Nagasaki Studies.”, HEALTH PHYSICS 1,390, 1959. STRUCTURES SHIELDING against FALLOUT GAMMA RAYS from NUCLEAR DETONATIONS, NBC SPECIAL PUBLICATION 570, Washington, D.C., U.S. Government Printing Office, 1980. U.S. Department of Defense and Energy Research and Development Administration. EFFECTS of NUCLEAR WEAPONS. Compiled by Samuel Glasstone and P.J. Dolan. Washington, D.C., 1977. PRINCIPLES OF PROTECTION, The US Handbook of NBC Weapon Fundamentals and Shelter Engineering Design Standards, Walton McCarthy, 727 pp. 2013, 6th edition, Brown Books.

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