Saturday, May 3, 2014

The Philosopher's Bomb, Part 2

Those Magnificent Men and their Atomic Machines

The Philosopher's Bomb: Discovering New Elements with Nuclear Explosions

Part II

Back to Part I

With Special Thanks to Dr. Stephen A. Becker and Dr. David W. Dorn

For first time readers, part I should be read before reading part II.

Operation FISHBOWL
On July 8th, 1962, at 11:00 pm local time, a Thor missile blasted off from Johnston Atoll in the Pacific Ocean. Fifty other rockets rose with it, from Johnston, Hawaii and California. Thirteen minutes and forty-one seconds later, the Thor touched its apogee 399 kilometers above the ocean and exploded, the light of its 1.4-megaton W49 warhead tearing through the Pacific night. The electromagnetic pulse from the blast destroyed street lights and triggered burglar alarms on Oahu 800 miles away, and created spectacular aurorae visible for more than 1,600 miles. This was STARFISH PRIME.[Su][ND]


Figure 17: Aurora from STARFISH PRIME Explosion[LANL]
(US Government)

STARFISH PRIME was part of a series of tests code-named Operation FISHBOWL and sponsored by Los Alamos Scientific Laboratory (LASL) and the Department of Defense. FISHBOWL's purpose was to develop techniques for penetrating missile defense screens. The escort rockets carried instruments measuring radiation flux, debris formation, and other technical data. Four other high-altitude tests followed as part of Operation FISHBOWL: CHECKMATE (October 20 1962), BLUEGILL TRIPLE PRIME (October 26 1962), KINGFISH (November 1 1962), and TIGHTROPE (November 4 1962).[DoE] One of those tests had an extra escort: a Nike Apache sounding rocket launched from Hawaii carrying samples of uranium-233 and -235 and a neutron counter.

The nuclear explosion produced a pulse of neutrons, spread over a range of energies. As the neutrons flashed through space, the slower ones fell behind. By the time they hit the uranium samples 150 kilometers over Hawaii they had sorted themselves neatly by energy.  The missile transmitted 23 seconds of data back to the ground station, measuring the fissions produced in the two samples. The probability of U-235 fission – the fission cross-section – at different energies was well-known; by measuring the ratio of U-233 and U-235 fissions the Lawrence Radiation Laboratory at Livermore (LRLL) scientists who had launched the rocket could calculate the probability of U-233 fission at different neutron energies.[Alb] These had previously been measured using less heroic methods, but the 1,280-kilometer separation between the neutron source and the samples drastically increased the resolution of the measurements.

There was some hope that FISHBOWL would be followed by other high-altitude tests incorporating physics experiments. But TIGHTROPE was the last US high-altitude nuclear test. Electrons produced by the STARFISH PRIME blast created an artificial radiation belt that destroyed a third of all satellites in Low Earth Orbit. Then, on August 5th 1963, the United States signed the Partial Test Ban Treaty. A consolation prize for negotiators who had hoped for a comprehensive ban, the treaty outlawed any nuclear tests in or above the atmosphere. STARFISH PRIME would not be repeated. To continue their experiments, the scientists of Los Alamos and Lawrence Livermore would have to go underground.

ANACOSTIA through KENNEBEC


For well into the 1950s, most US nuclear weapons tests took place in the Pacific. Multi-megaton hydrogen bombs could be tested far from inhabited areas, where the seismic shock and fallout couldn't harm civilians. That, at least, was the intention, though sometimes the precautions proved insufficient.

But, in 1950, the US government decided to move some tests to the continental United States. Thousands of miles from the laboratories, the Pacific testing sites were expensive to operate, and it took months to organize experiments so far from home. A testing site on the continent would be limited to low-yield shots, but would be cheaper and more flexible. The Atomic Energy Commission eventually chose a site within Nellis Air Force Base in Nevada, just 105 kilometers north of Las Vegas; they fired the first shot in 1951.[HDu] In the clear, desert air the tests could be seen for miles, and Vegas tourism officials made it part of the city's attraction – visitors could sip atomic cocktails (vodka, brandy, sherry, and champagne) and watch the drifting mushroom clouds between rounds of gambling.[Wo]


Figure 18: Mushroom Cloud Seen from Las Vegas[NNSA]
(US Government)

The Partial Test Ban Treaty ended the show, but not the tests. Testing moved underground, and almost all of the underground tests took place in Nevada. Hundreds of meters beneath the scorching desert sand, AEC scientists put the deadliest weapons ever built through their paces. And Plowshare – the AEC's program to find peaceful uses for the atomic bomb – followed the weapons tests.

The head of device design at Livermore for the Plowshare project to make heavy elements was Dr. David W. Dorn. Dorn earned his Ph.D. in physics from Purdue University after serving in the Navy in Korea, and joined Livermore in 1959.[Do3] He was heavily involved with both the superheavy elements program and the nuclear excavation program. In the early '60s, the AEC weapons labs gave their scientists considerable autonomy in choosing their own projects; Dorn recruited personnel for the Plowshare program by telling prospective recruits that nuclear explosives are “so attractive that they will be used, and if you join us, we can make sure they are designed so as to maximize the useful effects and minimize the unwanted side effects.”[Do]


Figure 19: David W. Dorn Today[Do]
(Used with Permission)

His counterpart at Los Alamos Scientific Laboratory (LASL) was Jordan Carson Mark, a Canadian immigrant, mathematician, and leader of the lab's theoretical division. Mark had worked at Los Alamos since the Manhattan Project. Ted Taylor, a Los Alamos physicist, said that Mark “had a unique way of stimulating no-nonsense approaches to creativity. He kept intimate track of the many new and complex accomplishments of an incredibly productive group of staff members and eminent consultants.”[Co4][PBB]

Dorn and Mark planned to use tests at the Nevada Test Site (NTS) to develop nuclear explosives for the heavy element program. Then, once a suitable device had been produced, they would return to the GNOME site in New Mexico for the actual explosion, codenamed COACH. New elements could be chemically recovered far more easily from the Carlsbad salts than from the hard Nevada alluvium.

COACH would need a high but uniform neutron flux, and a yield low enough to be fired in the Carlsbad salts without damaging nearby buildings.[HD] Higher neutron fluxes were achieved by designing the devices to “maximize the neutron density within a relatively small volume of burning thermonuclear fuel surrounding a uranium target and to slow the disassembly time”[Co] – that is, to maximize how long it took for the assembly to blow itself apart. David Dorn described it as trying “to create a 'ball of thermal neutrons' and hold it together long enough for multiple neutron captures to take place. This had never been done on the scale we were attempting, and we were sensitive to the audacity of even thinking we could do so.”[Do]

Dorn's team fired the first heavy element test, code-named ANACOSTIA, at NTS on November 27th, 1962.[DoE] Workers drilled a 229-meter vertical shaft into the desert alluvium, lowered the device into it, refilled the hole, and detonated it. The 5.2-kiloton device hit a uranium-238 target with a neutron flux of between 2.5 and 4 moles per square centimeter. (A mole is a unit of measurement counting numbers of particles; for neutrons, one mole equals about one kilogram). ANACOSTIA reached a flux greater than the original MIKE test, at 2 to 3 moles/cm2, but with a yield 2,000 times lower.[Be2] After the blast, workers drilled back into the “shot chimney” of shattered stone and retrieved samples of rock mixed with solidified bomb debris.


Figure 20: Retrieving Samples from a Nuclear Test[Wa]
(US Government)

Chemists screened the samples for radioactivity, and pulverized the hottest rocks. They then dissolved the powder in a mixture of nitric, perchloric, and hydrofluoric acid to remove the silica, a tricky process which produced what the chemists understatedly described as a “vigorous exothermic reaction”. Then they mixed the residue with tri-n-butyl phosphate-nitrate (TBP), followed by a mixture of di-2-ethylhexyl orthophosphoric acid and nitric acid (HDEHP) to extract the lanthanides and transuranics. Finally they passed the material through a series of ion exchange columns, producing a residue of transuranics, the heavy elements produced by the intense flash of neutrons from the explosion. Because of the radiation, most of this work had to be done by remote control behind lead shielding.[WDFH]


Figure 21: TBP and HDEHP Extraction Apparatus[WDFH]
A: Lines to AL(NO3)3, NH4NO3, and HNO3 wash solutions and to water;
B: TBP transfer vessel; C: HDEHP transfer vessel; D: typical solenoid valve;
E: TBP mixing vessel; F: stainless-steel centrifugal stirrer; G: HDEHP mixing
vessel; H: Teflon gland; I: air pressure line; J: 4-liter feed solution vessel;
K: 4-liter vessels for receiving waste solutions or product
(US Government)

The analysis showed that, below mass 246, ANACOSTIA produced a higher relative yield than MIKE:


Figure 22: ANACOSTIA and MIKE Relative Yields[HD]
Note logarithmic scale
(US Government)

Californium-252 and -254 were also detected in the ANACOSTIA samples, but at concentrations too low to be confident they weren't from contaminated laboratory equipment.[HD]

Three more tests followed in the 1962-63 testing season: KAWEAH (Feb. 21st 1963, 3 kT), GERBIL (March 29th 1963, less than 20 kT), and KENNEBEC (June 25th 1963, less than 20 kT).[DoE][GURC] Dorn's team at Lawrence Livermore designed KAWEAH and KENNEBEC, while Mark's group at Los Alamos designed GERBIL. ANACOSTIA, KAWEAH, and KENNEBEC were funded directly by the AEC's new Division of Peaceful Nuclear Explosives, but GERBIL was primarily a weapons test, with the heavy element experiment incorporated as an add-on.[DoE] This would be a common tactic in later years: by joining forces with weapons testers, the Plowshare scientists could save the not-incosiderable cost of building the device and emplacing it hundreds of meters underground. After 1963, most of the superheavy element tests would follow GERBIL's lead, piggybacking on weapons tests to reduce costs.

KAWEAH and GERBIL were failures[Do3], but KENNEBEC reached a flux of 4.6 to 6 moles/cm2.[Be2] Irradiation for a year in the High Flux Isotope Reactor at Oak Ridge – a nuclear reactor specifically designed to produce superheavy isotopes by neutron transmutation – produced only 0.15 moles/cm2.[Do3]

While they had not yet reached a neutron flux that would justify proceeding to COACH, ANACOSTIA and KENNEBEC showed promise. In October of 1963, the AEC placed the camp at the GNOME site on standby status, while development continued at the Nevada Test Site.[JCAE65]

After 1962, Livermore took the lead in the superheavy element program. Los Alamos continued to sponsor superheavy element tests, but focused primarily on other types of neutron physics experiments. The two laboratories cooperated closely on the experiments, although each took different approaches. According to Dr. Dorn, Livermore “had more freedom to innovate and 'blue sky' our approaches.” “The focus of [Livermore] was more on deliverables, while [Los Alamos] made sure that the underlying physics was well understood. We were a team and the combined focus served both laboratories well.”[Do]

Prompt Sample Recovery
Besides improving the devices themselves, Livermore and Oak Ridge National Laboratory also worked on prompt sampling systems – mechanisms to rapidly recover products of the explosion. Conventional drilling took at least 36 hours to recover samples from the blast; since many heavy elements decay in hours, minutes, or less, they would be gone before drill teams could reach them. Developers of prompt sampling systems sought to retrieve samples essentially instantaneously.

TAMALPAIS and GNOME were not the first nuclear tests to incorporate prompt sampling systems. The idea actually originated with the weapon designers, as a way to get information on a weapon's performance. A prompt sampling system would hopefully be cheaper than drilling as well as faster.

The first prompt sampling systems, developed under Gary Higgins at Lawrence Livermore, were used during the HARDTACK II test series in 1958. However, these early systems were legendarily unreliable. The pipes could allow the blast to escape; at least two major ventings were attributed to prompt sampling pipes. More often, they failed to actually collect any material; the joke was that the best way to keep radiation from leaking through instrumentation cabling pipes was “to always, on all drawings, and when discussing them, speak of them as rad chem sampling devices.” Unfortunately, relatively little information on these systems is available in the public domain, presumably because of their use in weapons test diagnostics.[Ca]

Both the ANACOSTIA and KAWEAH tests included experimental prompt sampling systems. 10-inch-diameter pipes led from the bomb chamber to the surface, where they connected to horizontal pipes leading to holding tanks 650 feet from ground zero. The bottoms of the pipes were filled with a mixture of 50% starch and 50% water by weight. This mixture is ordinarily solid, but becomes fluid when squeezed – a property called thixotropicity. The tops of the pipes were filled with water.

When the bomb detonated, the pressure of the blast liquified the starch-water mix and drove fragments of the target into the pipe, then crimped the pipe shut. The material was then carried to the surface and from there to the holding tanks. Catchers mounted in the pipes intercepted some of the material for quick analysis, while the remainder settled in the tanks for later retrieval. 10 to 40 kg of material was delivered in this way from ANACOSTIA, and 360 kg from KENNEBEC.

Although elegant in theory, the material from the catchers showed a lower level of radioactivity than material retrieved from the melt puddle by drilling, and Livermore decided to leave the material in the tanks and use samples retrieved by drilling.[Br]

Starting in 1961, Oak Ridge, working with the Pitman-Dunn Institute for Research at Frankford Arsenal, investigated two alternative approaches to sampling: the jet sampler and the bubble sampler.[CTD62]

The bubble sampler was a pipe beginning several meters away from the bomb. When the bomb detonated, the explosion cavity would reach to within a meter of the inlet. In the moment after the blast, “special methods” – presumably explosives – would be used to open a connection between the pipe and the cavity, allowing retrieval of gas from the cavity just a few tenths of a second after detonation. To protect the pipe from the blast, it would initially be filled with water and surrounded with conventional explosives. The explosives would create a “gas blanket” that would attenuate the nuclear shock wave. The bubble sampler never proceeded beyond paper studies, and development seems to have been abandoned after 1964.[CTD61][CTD65]

The jet sampler used shaped high explosives to shoot a target one meter from the bomb up a 100 meter pipe at a speed of 10 to 100 kilometers per second, after it had been irradiated by the bomb but before the blast wave reached it. Mathematical models suggested that up to 50% of the original target could be retrieved in this fashion, compared to three parts in a trillion for the GNOME sampler.

Oak Ridge conducted live-fire jet sampler experiments at Frankford Arsenal beginning in 1962 or 1963, using 25mm targets made variously of uranium, copper, iron, or aluminum. The jets were slower than they had hoped, but still fast enough to escape a nuclear blast. At least 50% of the material made it to a 3-foot-thick, laminated wood block placed at the end of the 55-foot-long pipe as a “catcher”, suggesting that this would be an effective approach for use in the field.[CTD63][CTD64][CTD66]

Later experiments, performed some time in 1966 or 1967, used five copper cones, each plated with 3 grams of gold that had been irradiated in a nuclear reactor. Neutron-activated gold-198 simulated superheavy elements and, since it was radioactive, could be easily tracked.[CTD66][CTD67] However, the results of these later experiments seem to have been lost, and there are no records of the hypervelocity jet sampler program after 1967.

ANCHOVY through BARBEL


In the 1963-64 testing season, codenamed Operation NIBLICK, Livermore and Los Alamos conducted another three superheavy element tests, all as add-ons to weapons tests: ANCHOVY (November 14th 1963, less than 20 kT, Los Alamos), GREYS (November 22nd 1963, between 20 kT and 200 kT, Livermore), and OCONTO (January 23rd 1964, 10.5 kT, Livermore).[GURC][DoE] ANCHOVY was the most successful of the three, but even it reached only 2 to 3 moles/cm2 flux, worse than ANACOSTIA.[Be2][Do3]

The next testing season began to see real results. The first test of Operation WHETSTONE, BYE (July 16th 1964, 20 to 200 kT, Livermore)[DoE], was another failure, but the 38-kiloton PAR test of October 9th 1964 reached a flux of 11 moles/cm2 [Be]. Atoms of the uranium-238 sample absorbed up to 19 neutrons – two more than in MIKE – producing isotopes as heavy as Fermium-257. One of the isotopes that was produced was Curium-250 – the first time that isotope had been detected, and the first major success for the heavy element program.

A second test, BARBEL (October 16th 1964, less than 20 kT, Los Alamos), replicated PAR's neutron flux and managed to reach Fermium-257.[LARG] PAR was funded by the Plowshare program, while the other two were weapons test add-ons.[DoE]

This was not the only new result. Radiochemists at the nuclear labs discovered previously-unknown alpha decay paths of the rare, short-lived isotopes californium-253 and einsteinium-255. These isotopes had been produced before in nuclear reactors, but reactor-produced samples were heavily contaminated with other isotopes of the same elements, drowning out the signal of these decay modes. Radiochemists also tried to make the previously-unknown isotope fermium-258 by irradiating Fm-257 produced by the nuclear shots in a reactor, but without success.[CRG]

In all of the tests, the yields showed a sawtooth pattern: isotopes with even masses were relatively more abundant than isotopes with odd masses. This was expected; nuclei with odd numbers of neutrons have higher neutron capture cross-sections than those with even numbers. Uranium has an even number of protons, so an odd mass number meant an odd number of neutrons. Thus an odd-mass uranium atom would be more likely to absorb another neutron and reach a higher mass than an even-mass one. But, after mass 250, the pattern reversed:


Figure 23: PAR and BARBEL Isotope Yields[CRG]
Note: Some points are missing due to the short half-lives of the isotopes
(US Government, modified by author)

This pattern reversal was a mystery. Several hypotheses were advanced: David Dorn and R. W. Hoff of Livermore suggested that, as the even-mass nuclei beta-decayed after neutron capture, they passed through a region with a very high spontaneous fission rates, whereas the odd-mass nuclei did not. Although not impossible, this would be an odd coincidence.[DH]

P. R. Fields and H. Diamond of Argonne National Laboratory suggested an unanticipated side-reaction was occurring: un-fusioned deuterium ions were colliding with U-238 nuclei, fusing with them and expelling a neutron, producing neptunium-238. Since neptunium has one more proton than uranium, even mass numbers would correspond to odd numbers of neutrons, reversing the effect. Only about 1 in 1000 U-238 atoms would be converted to neptunium, but neptunium isotopes have a larger capture cross-section than uranium isotopes, and so disproportionately reach higher mass numbers.[Be2] For the moment, though, the question remained open.[LARG]

The AEC fired two more heavy element tests in the 1964-65 testing season: SCAUP (June 14th 1965, less than 20 kT yield, Los Alamos) and TWEED (July 21st 1965, less than 20 kT, Livermore).[DoE] Both tests failed, but TWEED incorporated a new twist: the target was neptunium-237 mixed with plutonium-242 rather than uranium-238.[In][Ec] Dorn's team hoped that, since Pu-242 was four nucleons heavier than U-238, the shot would produce correspondingly heavier elements. Calculations indicated the shot reached a 12 mol/cm2 neutron flux[Ec], but the heavy element yield was worse than in PAR and BARBEL – possibly the plutonium had fissioned when struck by neutrons rather than absorbing them. However, it was not clear whether this was a solid result, or if the neutron flux had actually been lower than they thought.[Bel]

Even at 12 mol/cm2, though, the devices were still not ready to move back to the GNOME site in New Mexico for the COACH test. And the AEC was getting tired of paying for the New Mexico camp's upkeep.

The AEC cut funding for the camp for fiscal year 1965 to $60,000; the next year, they eliminated it entirely.[JCAE66] John Kelly, director of the AEC's Peaceful Nuclear Explosives division, reassured Representative Thomas Morris of New Mexico that this did not mean COACH was cancelled:

Morris: It doesn't seem to me that Project COACH is very much alive...

Kelly: No, I think Project COACH is alive...we have been carrying this Carlsbad site for-I don't know-$60,000 a year. It is in sort of a semiready standby basis. I hope we can completely button it up and reduce the standby costs. This is the reason I am having the field office look into what is the minimum that we can maintain this site for. I think it will be a rather small number so I didn't budget any specific total for that.”[JCAE66]

This is the last time Project COACH appears in the public record. It does not seem to have ever been formally cancelled, but improvements in drilling and chemical analysis made it unnecessary,[JCAE65B] while the public was becoming more and more restive about nuclear tests in places like New Mexico, outside of the unpopulated waste of the Nevada Test Site.

PIPEFISH through PETREL


While Livermore focused on superheavy element experiments, Los Alamos worked more on other areas of neutron physics. The Los Alamos program, although it included some superheavy element tests, focused on using nuclear explosions to measure reaction cross-sections and do other neutron measurements. Bernard Diven, a scientist working on the program, said “it was great fun. We would just piggyback a regular weapon shot that's going to take place and it looked like it was a kind of a bomb that would be good for us to work on and we would just ask them for a line-of-sight, which is really a pretty big deal but the test division people would accommodate these things.”[Di2]

The first known Los Alamos neutron physics test after GNOME was code-named PIPEFISH (April 29 1964, less than 20 kT). PIPEFISH was essentially a feasibility test, and did not produce any useful data. There may have been other neutron physics experiments between GNOME and PIPEFISH – the naming scheme suggests there were two unidentified physics tests. But PIPEFISH was the first where the signal of the neutron pulse could be discerned from the background.

PIPEFISH was followed eight months later by PARROT. A pipe ran from the 1.3-kiloton PARROT device through a four-foot-long steel collimator to the surface. A 17-foot-wide, 50-foot-tall metal tower sat above it, mounted on truck tires to protect it from the ground shock.[HDB][DoE]


Figure 24: PARROT Physics Tower, Before theTest[He2]
(US Government)

The neutron beam would pass through seven foils of various isotopes – plutonium-239, -240, -241, and -242, lithium-6, uranium-235, and a blank to measure background. Each foil was mounted at an angle to the beam. Fragments of atoms split by a passing neutron would escape the film to electronic detectors mounted to the side, to measure the fission cross-section. After the seven fission foils were two thicker slices – still less than 0.3 mm – of bismuth-209 and uranium-235. These were mounted next to gamma-ray detectors, to measure the percentage of neutron captures in uranium-235 that resulted in fission. The bismuth, like the blank foil, served to measure the background. Finally came a 3-centimeter layer of aluminum, whose total cross-section they wanted to measure, and then a neutron counter – eight separate experiments on a single beam.


Figure 25: Typical Experiment Stack[He]
(US Government)

Since the tower would be destroyed when the ground subsided after the blast, some of the more valuable equipment was mounted on sleds, to be winched to safety after the detonation but before the subsidence reached the surface.

The Los Alamos team fired PARROT on December 16th, 1964.[He2]


Figure 26: Physics Sled Being Winched to Safety[HDB]
(US Government)


Figure 27: PARROT Tower After Test[He2]
(US Government)

The data produced by PARROT was of questionable accuracy. Among other issues, neutrons reflected from the bottom of the explosion cavity caused “ghost” peaks on the measurements.

At least one of the PARROT sleds was reused a year later in the 1.3 kT PETREL test, on June 11th.[DoE] PETREL added a 5 cm polyethylene moderator shielded by lead to the pipe above the bomb, which would reduce gamma contamination from the explosion and slow the neutrons. Nine different experiments were mounted on this one test, measuring the fission cross-sections of plutonium-239, -240, and -241, uranium-233 and -235, and americium-241 and -242m, and the capture cross-sections of plutonium-240 and uranium-238. Some of these cross-sections were already known, serving to confirm the technique's viability, and some were new.[HDB]


Figure 28: PETREL Tower[Di2]
(US Government)

So far, the tests had mostly replicated earlier results in order to prove the method. The data produced had been as or less accurate than achieved using less heroic methods, but given the enormous amount of neutrons produced in nuclear shots, there seemed to be a clear path to improving the accuracy to surpass traditional methods.[Di4]

The Plowshare Program in 1965
Scientific research interested the scientists of Lawrence Livermore and Los Alamos, but it held less appeal for the US Congress. The AEC sold the Plowshare program to Congress on the basis of nuclear excavation, and, as a result, the future of the heavy element project was inevitably tied to the excavation program.

Between 1962 and 1965, the Plowshare excavation program fired eight nuclear tests. These tests included the 104-kiloton SEDAN shot, which dug the largest man-made crater in the continental United States.[DoE]


Figure 29: SEDAN Explosion[NNSA2]
(US Government)

Funding for Plowshare increased from $2.6 million in modern dollars in 1958 to $94 million in 1964.[PWA60][PWA66]


Figure 30: Plowshare Funding, 1958-1965, Modern Dollars
[PWA60][PWA61][PWA62][PWA63][PWA66][JCAE67][JCAE68][JCAE69][JCAE73]
(Author)

Nuclear excavation appeared to be off to an excellent start. But it was already struggling with the obstacles that would ultimately kill it.

When President Kennedy signed the Partial Test Ban Treaty, AEC Chairman Glenn Seaborg had promised congress the treaty would not impede the Plowshare program. That promise proved to be flat-out wrong.

The treaty prohibited nuclear explosions that resulted in “radioactive debris” crossing national boundaries. But the treaty did not define “debris”. The AEC thought the term meant fallout in sufficient quantity to endanger human health. The State Department and the Arms Control and Disarmament Agency (ACDA) thought it meant any fallout, no matter how small. (The Russians' opinion appeared to depend on whose fallout was under discussion.) If the AEC's view prevailed, the Plowshare excavation program would be delayed but could still continue, as Seaborg had promised. If State and ACDA won, then either the treaty would have to be modified, or nuclear excavation would have to be abandoned.

On October 31st, 1963, President Kennedy established a committee to review nuclear tests which might be accused of violating the PTBT, which came to be called the 269 committee after the memorandum establishing it. In practice, the 269 committee was dominated by State and ACDA. Plowshare could continue developing nuclear excavation devices – such tests could be done deep underground, with no risk of releasing fallout. But permission to conduct cratering tests, which would breach the surface, became harder and harder to get.[SL] And Plowshare needed a series of cratering tests. They needed to know exactly how much earth their bombs would move, and where to.

And the opposition was not only within the government. The public was becoming increasingly wary of nuclear testing, and tests outside NTS were drawing more and more protest.

After SEDAN, the AEC had planned to fire six cratering tests over the next five years. By the end of 1965 they had fired only two cratering tests: SULKY and PALANQUIN, both in the NTS.

And, of course, no actual deployment of the technology could move forward unless the treaty was revised. The Russians had indicated their willingness to revise the treaty – they were becoming interested in peaceful nuclear explosives themselves – but the moment never seemed quite right. Fundamentally, the problem was that Plowshare had very little support in the government outside of Congress and the AEC itself.[Ki]

For the moment, though, none of these issues effected the heavy element and neutron physics programs.


With Special Thanks to my Pre-Readers, J. Fletcher and B. Bennet

Citations can be found here.

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