When Did the Nuclear Age Begin? 70 Years Ago, Today

, physicist & co-director, Global Security | July 16, 2015, 9:11 am EDT
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Seventy years ago today, the United States exploded the first atomic bomb in the New Mexican desert, at the Alamogordo Bombing Range. Thus began the nuclear age.

The bomb was later determined to have the explosive power of 21,000 tons of TNT. But in addition to a blast wave, and intense heat and light, this bomb produced something new: radioactivity. High levels of radiation spread as far as 90 miles from the test site, dropped by the mushroom cloud as it dispersed toward the northwest.

The Trinity Test

The Trinity explosion (Source: Jack Aeby, DOE)

The Trinity explosion (Source: Jack Aeby, DOE)

The test, code-named “Trinity,” was of a plutonium bomb. During the Manhattan Project, the United States built two types of atomic weapons—one using uranium, and one using plutonium. The uranium bomb had a design that was almost assured of working. And the United States had only been able to produce enough uranium for one bomb—the one that destroyed Hiroshima, Japan on Aug 6, 1945.

But the plutonium bomb needed a more complicated design. It was an implosion-type weapon, which required a spherical shell of conventional high explosives to detonate symmetrically around a plutonium core to compress it enough to create a critical mass, thus allowing the plutonium to fission. And the United States had produced enough plutonium for several bombs—so one could be used up in a test.

Some of the scientists had worried that the test might ignite the atmosphere, but decided that this was a low enough probability to proceed with the test.

Others believed the bomb would not work at all. They were proved wrong, and another such weapon was dropped on Nagasaki on August 9.

Another nuclear milestone

Another milestone of the nuclear age was the 1952 “Ivy Mike” test by the United States of the first “hydrogen” or “thermonuclear” weapon. Such weapons can be much more powerful than the atomic bombs used on Hiroshima and Nagasaki. They have two stages, the first of which is essentially a plutonium-based atomic bomb. Because these weapons are complex, to confirm that a new design will work, it needs to be explosively tested.

Testing, testing, testing…

Following the Trinity Test, the United States, Soviet Union, Britain, France, and China conducted some 500 nuclear tests above ground, leaving a detectable layer of radioactive elements in sediment worldwide. The tests also resulted in strontium-laced milk from cows that had eaten grass contaminated by fallout. In response to growing public concern about the effects of radioactivity, an international treaty banned above ground testing went into effect in 1963 and these nations switched to underground testing, which largely eliminated fallout. (However, some underground tests have “leaked” and vented radioactivity into the atmosphere.)

Since 1963, another 1,500 tests have been conducted worldwide, and India, Pakistan and North Korea have joined in. (There is lingering disagreement about whether Israel, which has nuclear weapons, conducted an atmospheric test in 1979 off Antarctica.)

An international treaty banning all nuclear testing—the Comprehensive Nuclear Test Ban Treaty (CTBT)—was negotiated in 1996. Only India, Pakistan and North Korea—which have not signed the treaty—have tested since then. The United States was not just the first to test—it has conducted the most tests: 1,054. It produced 65 different types of nuclear weapons.

New nuclear weapons

The main motivation for negotiating the CTBT was that it would both prevent existing weapon states from developing new types of nuclear weapons and prevent other nations from going nuclear. The 185 non-nuclear parties to the Nuclear Non-Proliferation Treaty (NPT) have made the CTBT a priority for the five nuclear states to fulfill their obligations under the NPT.

But now the United States has called into question the efficacy of the CTBT. Scientists at the U.S. weapons laboratories now believe that their computer simulations are sophisticated enough that the United States can forgo nuclear testing of new designs. Despite President Obama’s pledge to “not develop new nuclear warheads” the United States is planning to do just that. The alternative is for the United States to refurbish existing weapons, which it has done to date.

This plan to develop, produce and deploy new types of nuclear weapons undermines the CTBT, and hence the NPT. Yet it is in U.S. security interests to strengthen these two international regimes.

Moreover, while U.S. weapons designers may be confident that these new weapons will work as intended even if they do not undergo nuclear testing, future U.S. policy makers may not share this confidence and push for a resumption of U.S. nuclear testing. This would likely unleash a spate of nuclear testing by other nations.

For these reasons, the United States should abandon its plan to develop and produce new weapons. It could finally end the continuous development of new weapons that it began 70 years ago.

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  • atomikrabbit

    The nuclear age should more accurately be thought of as beginning on December 2, 1942 when Enrico Fermi’s team achieved the first self-sustaining nuclear reaction by using ultra-pure graphite to moderate the spontaneous neutron emissions of natural uranium. The reactor eventually was operated at up to 250 watts of power.

    Nuclear WEAPONS came of age with the Trinity test, when a prompt supercritical assembly was achieved in the artificial isotope plutonium-239, through herculean efforts, by some of the greatest minds of the 20th century, in order to end a horrific world war.

    Let’s not contribute to the ongoing conflation of peaceful power reactors with weapons.

  • AuldLochinvar
  • AuldLochinvar

    When I read that the refurbishing of the TVA’s Watts Bar reactor included a facility to provide tritium to maintain the DoD’s thermonuclear weapons capability, I was dumbfounded at the hypocrisy of not reprocessing “nuclear waste”. That was supposed to be so that there would not be diversion of the plutonium, which surely should be co-precipitated with enough uranium to be only reactor grade.

    • atomikrabbit

      DOE got out of the tritium business (or at least the reactors at Savannah River that produced it), several decades ago. In essence, they have subcontracted it to TVA, which under their charter is required to support national defense. Fresh gaseous tritium is required for boosted fission weapons (or thermonuclear primaries) since H3 has a 12 year half-life.

      After an appropriate safety analysis and NRC license amendment, some burnable poison rods at WB-1 were replaced with special tritium-breeding ones containing Li-6. During refueling outages these rods are removed and transported to SRS where special facilities exist for tritium extraction.

  • Ms Myriad

    We already have bombs that can wipe entire cultures off the map in an eye-blink and we want to build MORE and STRONGER ones?!?! Is the actual goal to end Terran life as we know it, or is that just an inconvenient side-effect?