Initial nuclear radiation

Radiological warfare(RW) may be defined as the employment of agents or weapons to produce residual radioactive contamination,as distinguished from the initial effects of a nuclear explosionfblast, thermal, and initial nuclear radiation) defense against such warfare (Ref 12,p 233)... 

B. Surface Burst. A surface burst weapon is detonated on or slightly above the surface of the earth so that the fireball actually touches the land or water surface. The area affected by blast, thermal radiation, and initial nuclear radiation will be less extensive than for an air burst of similar yield, except in the region of ground zero where destruction is concentrated. In contrast with airbursts, local fallout can be a hazard over a much larger downwind area than that which is affected by blast and thermal radiation. 

C. Subsurface Burst. A subsurface burst weapon is detonated beneath the surface of land or water. Cratering will generally result from an underground burst, just as for a surface burst. If the burst does not penetrate the surface, the only other hazard will be from ground or water shock. If the burst is shallow enough to penetrate the surface, blast, thermal, and initial nuclear radiation effects will be present, but will be less than for a surface burst of comparable yield. Local fallout will be very heavy if penetration occurs. 

C. Neutron-Induced Activity. If nuclei capture neutrons when exposed to neutron radiation, they will, as a rule, become radioactive and then decay by emission of beta and gamma radiation over an extended period of time. Neutrons emitted as part of the initial nuclear radiation will cause activation of the weapon residues and environmental material, such as soil, air, and water. For example, a small area around ground zero may become hazardous as a result of exposure of the minerals in the soil to initial neutron radiation, due principally to neutron capture by sodium, manganese, aluminum, and silicon in the soil. This is a negligible hazard because of the limited area involved. 

Initial nuclear radiation is directly emitted by the nuclear reaction, conventionally in the first minute after the explosion. It essentially comprises gamma and neutron radiation, which therefore propagates at velocities equal or close to the velocity of light. Its energy is equal to about 5 per cent of the total produced by the explosion. One metre of concrete... 

The dose resulting from the initial nuclear radiation depends in a complex way on the explosion power and on distance, and on the density variations of air due to the blast (the hydrodynamic increment due to the rarefaction of air behind the shock wave at high explosion energies). Tables 22-1 and 22-2 detail three values of gamma and neutron doses, respectively, and distance (in air from the explosion centre) for three typical explosion energies. Other values can be interpolated or extrapolated. The uncertainty is equal to a factor of two in both ways. 

Initially, DADC polymers were used in military aircraft for windows of fuel and deicer-fluid gauges and in glass-fiber laminates for wing reinforcements of B-17 bombers. Usage in impact-resistant, lightweight eyewear lenses has grown rapidly and is now the principal appHcation. Other uses include safety shields, filters for photographic and electronic equipment, transparent enclosures, equipment for office, laboratory, and hospital use, and for detection of nuclear radiation. 

The data obtained here for intermittent stress application (Figure 8) on a polystyrene sample and the data of Mokulskii et al. (Figure 9) for creep of a PVC sample after various times of exposure to the nuclear radiation field can now be interpreted in terms of continued gas buildup within the samples during radiation exposure. This leads to the higher initial creep rates when stress is applied after the radiation beam has... 

The Effect of Nuclear Radiation on the M26 Primer and M19A2 Detonator , Proceedings of 1957 Electric Initiator Symp, Chapt XXXI, Franklin Inst (Sept 1957) 54) A.C. McLaren,... 

FIGURE 15.23 Percent change in initial tensile shear strength caused by nuclear radiation dosage.7 ... 

Two principal exceptions are resin breakdown caused by sustained exposure to ionizing nuclear radiation and powerful chemical oxidizing agents such as nitric acid, chromic(VI) acid, chlorate(V) ions, halogens, and peroxy compounds. Even saturation levels of dissolved oxygen in the presence of transition metal cations may initiate chemical breakdown albeit only relatively slowly at ambient temperatures. 

E. Enhanced Radiation (ER) Weapons. An enhanced radiation weapon has an output in which neutrons and x-rays are made to constitute a substantial portion of the total energy released. An ER weapon s total energy would be partitioned as follows 30% as blast 20% as thermal 45% as initial radiation and 5% as residual radiation. A 3-kiloton ER weapon will produce the nuclear radiation of a 10-kiloton fission weapon and the blast and thermal radiation of a 1-kiloton fission device. 

In considering the absorption of nuclear radiation it is appropriate to view the overall process from two aspects (1) processes occurring to the nuclear particles themselves as their energies are reduced to the thermal equilibrium value such absorption processes are the principal consideration of this chapter (2) processes in the absorbing material due to the effect of the transfer of energy. This transfer results initially in excitation and ionization which cause physical and chemical changes. The study of these effects is the domain of radiation chemistry and is considered in Chapter 7. 

In arriving at this synthesis comprehensive studies were summarized of initiation by stimuli such as heat, light, shock, and nuclear radiation. In spite of earlier suggestions to the contrary (see Chapter 9), little evidence was found that tribo-chemical fracture of crystals leads to detonation. Nitrogen tri-iodide was the only substance known to explode under ionizing radiation. The failure to achieve initiation in other substances was discussed in terms of the limited-size hot spots introduced by nuclear particles. This interpretation was consistent with the observation that hot spots of 10" -10" cm diameter are necessary to produce self-sustaining decomposition. 

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