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Posted by on Dec 11, 2008 in At TMV | 11 comments

Fusion vs. Fission: Not All Nukes Are Created Equal

Holly’s recent post about Obama offering Israel an “umbrella” of deterrence contained an assertion that I’ve often seen and drives me absolutely crazy.

1) A nuclear strike against Israel could kill almost half of the Jews in the world (as well as many Christian and Muslim Arabs) and would threaten the survival of the Jewish People. Both the State of Israel and the Jewish People are far more interested in survival than revenge.

The implication is that a single nuclear attack would be sufficient to “wipe Israel off the map” which is absolutely not true in the slightest. The problem is that in common parlance we call both fusion and fission based weapons “nuclear” even though fusion bombs are orders of magnitude more powerful. The measurement for large explosives is to talk about the equivalent amount of TNT that would be needed to produce the same effect. A 2000 pound bomb is a standard sized bomb dropped by planes to attack targets in war, while nuclear weapons are talked about in terms of tons of TNT. Fission weapons use either enriched uranium or plutonium to produce the explosion, and most weapons are between 14 and 20 kilotons. Fusion weapons use hydrogen to create the primary explosion (there is actually a fission-based trigger that explodes in order to start the fusion) and those weapons range between 500 kilotons for independently targeted warheads to 20 megatons for large but mostly obsolete bombs. When talking about the individually targeted warheads, multiple warheads detach from the same missile (the missile is known as MIRV‘d) with the currently used Trident missile containing 8 warheads for a total of around 4 megatons. This means that one fusion missile is 300-1000x more powerful than a fission bomb.

Hiroshima was attacked by a uranium-based weapon, and an attack by Iran would be similar to this scale, not the hydrogen-based weaponry that we were worried about Russia using during the Cold War. In Hiroshima, around 70,000 people died from the direct effects, with another 70,000 dead within a few months. The area of total and massive devastation was around 2 miles in diameter, however, Hiroshima was not a modern city and they were not prepared for an attack. As it’s made clear in the book Hiroshima, many of the deaths were actually due to the firestorm that raged through the city’s wooden buildings and the reason why around 70,000 died in the aftermath was because they had no clean water, food or medical attention. A modern city with properly stocked bomb shelters would see much less devastation.

In order to destroy Israel, Iran would need to build many weapons. To obliterate even 1/100th of Israel’s territory (85 sq mi) would require over 25 bombs, assuming the same destruction patterns as Hiroshima. Even if Iran was competent at producing its uranium, it would still take over 6 months to create enough for one bomb. This means that Iran is over a decade away from being able to threaten Israel even if they were technically proficient and had the desire. Meanwhile, one US Ohio class submarine has 24 Trident missiles, for a total destructive power of nearly 100 megatons, and while Israel’s full capabilities are not known, they are believed to have dozens of weapons and submarine based missiles with the 4-20 megaton range.

There is no possible way that Iran can threaten Israel on a fundamental level with fission based weaponry, and to even do serious damage would require decades of production. Meanwhile, a single sub from either Israel or the United States could destroy most of Iran. The only purposes for building fission bombs are for a) propaganda and b) to potentially be able to attack forward operating bases during an invasion. It is the latter reason that we are so intent on countries not having nukes. When it comes to terrorism it should be noted that each bomb has a unique atomic signature and the source could quickly be determined, so the whole, “What if they give a bomb to a terrorist group that detonates it and then we can’t retaliate because we don’t know where it’s from?” is not a realistic question. The far greater terrorist threat would be in detonating a dirty bomb that contained ordinary radioactive material, and this material is widespread with thousands of pounds unsecured in the former Soviet states, or even medical and industrial waste. This is why Obama’s mission with Sen. Lugar to coordinate the securing of such material did far more to help deter a massive terrorist attack than trying to stop nations from developing weapons.

If Iran started a fusion program then obviously the calculus would change, and there are real consequences of Iran having The Bomb — namely giving it a freer hand to harass its neighbors more conventionally and thus leading to a weapons race — but any serious discussion needs to take the facts into account. Hyperbole will not serve us well.

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