<Tr> <Td> Total dose for acute radiation syndrome </Td> <Td> 1.2 </Td> <Td> 1.8 </Td> <Td> 2.9 </Td> <Td> 5.4 </Td> </Tr> <P> For the direct radiation effects the slant range instead of the ground range is shown here, because some effects are not given even at ground zero for some burst heights . If the effect occurs at ground zero the ground range can be derived from slant range and burst altitude (Pythagorean theorem). </P> <P> "Acute radiation syndrome" corresponds here to a total dose of one gray, "lethal" to ten grays . This is only a rough estimate since biological conditions are neglected here . </P> <P> Further complicating matters, under global nuclear war scenarios, with conditions similar to that during the Cold War, major strategically important cities, like Moscow, and Washington are likely to be hit not once, but numerous times from sub megaton multiple independently targetable re-entry vehicles, in a cluster bomb or "cookie cutter" configuration . It has been reported that during the height of the Cold War in the 1970s Moscow was targeted by up to 60 warheads . The reasons that the cluster bomb concept is preferable in the targeting of cities is twofold, the first is down to the fact that large singular warheads are much easier to neutralize as both tracking and successful interception by anti-ballistic missile systems than it is when several smaller incoming warheads are approaching . This strength in numbers advantage to lower yield warheads is further compounded by such warheads tending to move at higher incoming speeds, due to their smaller, more slender physics package size, assuming both nuclear weapon designs are the same (a design exception being the advanced W88). The second reason for this cluster bomb, or' layering' (using repeated hits by accurate low yield weapons), is that this tactic along with limiting the risk of failure, also reduces individual bomb yields, and therefore reduces the possibility of any serious collateral damage to non-targeted nearby civilian areas, including that of neighboring countries . This concept was pioneered by Philip J. Dolan and others . </P>

What is the radius of an atomic bomb explosion