Interaction of the blast wave, fire, and extent of blast damage are important factors in determining fire spread. Flash burns are likely to occur on a large scale as a result of an air or surface blast of a nuclear weapon. Because thermal radiation travels in straight lines, it burns primarily on the side facing the explosion. But under hazy atmospheric conditions a large proportion of the thermal radiation may be scattered, resulting in burns received from all direction. Depending on the size of the weapons, second-degree burns may be received at distances of 25 miles or more. The  intense  flash  of  light  that  accompanies  a nuclear  blast  may  produce  flash  blindness,  even  at  a range  of  several  miles.  Flash  blindness  is  normally temporary,  though,  the  eyes  can  recover  in  about  15 minutes in the daytime and in about 45 minutes at night. A greater danger lies in receiving permanent damage to your  eyes  caused  by  burns  from  thermal  radiation, which may occur 40 miles or more from a large-yield nuclear weapon. Under some conditions, individual fires created by a nuclear explosion can come together into mass fires with  great  potential  for  destruction.  The  most significant  types  of  mass  fires  are  divided  into  two categories—firestorms and conflagrations. FIRESTORMS.—In  a  firestorm,  many  fires merge to form a single column of hot gas that rises from the burning area. Strong, fire-induced, radial winds are associated with the column. Therefore, the fire front is essentially stationary and the outward spread of fire is prevented by the in-rushing wind. Virtually everything combustible within the firestorm area is destroyed. CONFLAGRATIONS.—Conflagrations  have moving fire fronts driven by the wind. Conflagrations can spread as long as there is fuel. Unlike firestorms, conflagrations can develop from a single ignition. Radiation Nuclear radiation hazards consist of alpha and beta particles, gamma rays, and neutrons. ALFA PARTICLES.—Alpha particles have little skin-penetrating power and must be taken into the body through ingestion or cuts to be injurious. BETA PARTICLES.—Beta particles can present a hazard to personnel if the emitters of these particles (carried  in  contaminated  dust,  dirt,  or  bomb  residue) come into contact with the skin or get inside the body. Beta particles with enough intensity cause skin burns (radiation burns). GAMMA RAYS.—Gamma rays are pure energy and not easily stopped. They can penetrate every region of the body. In fact, many gamma rays will pass right through a body without touching it. However, gamma rays that do strike atoms in the body cause the atoms to ionize.  The  ionization  may  result  in  any  number  of possible chemical reactions that damage the cells of the body. NEUTRONS.—Of  all  the  nuclear  radiation hazards, neutrons have the greatest penetrating power. When the neutron is captured in the atoms of various elements  in  the  body,  atmosphere,  water,  or  soil,  the elements  become  radioactive  and  release  high-energy gamma rays and beta particles. Initial radiation contains both gamma and neutron radiation.  Residual  radiation,  our  greatest  concern, contains both gamma and beta radiation. EFFECTS ON SHIPS AND SHIPBOARD SYSTEMS Ships  close  to  a  detonation  point  may  sustain considerable   material   damage   from   air   blast, underwater shock, water waves, and possibly thermal radiation. There will be a ship kill zone around ground zero. Outside ground zero, there will be a much larger damage-survival zone. Here, ships will receive severe, moderate or light topside damage as well as operational and equipment damage. Damage from an Air Blast Depending  on  the  weapon  yield,  the  blast  wave from  nuclear  detonations  can  cause  damage  to  ships miles from the blast. Damage will be inflicted primarily on the superstructure and the hull above the waterline. Some  examples  of  damage  from  an  air  blast  might include  the  warping  or  buckling  of  the  flight  deck;  a distortion  of  airplane  elevators,  hull  girders,  deck 13-11 Student Notes: