Conclusions of the DIIS report ”The marshal’s baton. There is no bomb, there was no bomb, and they were not looking for a bomb”

Some of the sources for a historical reconstruction of the events surrounding the recovery of the nuclear weapons after the Thule accident have been excised or made exempt from declassification.

In some respects, the conclusions presented here can not supply irrefutable evidence of past events. This is not unusual for historians, who must be content to establish the likely and the plausible.

With this in mind, we have concluded the following:

About the sources

The foreign minister’s specific question to DIIS was whether the 348 documents obtained by the BBC journalist Gordon Corera in 2001 contained decisive new information as compared with the 317 documents declassified by the Department of Energy (DOE) from 1986 onwards and released by DOE in September 1994.

No new document-based assertions about the bombs were made in 2008, and the documentary evidence was much the same as that released by DOE in 1994 and used in 2000 in an article in Jyllands-Posten. BBC’s second assertion about withheld information concerning the true meaning of the bottom survey could be called ‘new news’ as far as the extensive media coverage is concerned, but it was based on an old, well-known document that was declassified in February 1991 and formed part of the 317 collection of documents.

Our report is primarily based on the 348 collection, that is, the same U.S. documents that in many cases have been declassified for nearly two decades, but additionally it takes in a few documents from Danish and other archives. What is new in this report, in other words, is not so much the sources as the analysis and interpretation of mostly familiar documents.

About the weapons

We have shown beyond any reasonable doubt that all four weapons broke up in the crash and became nonoperational: they did not exist as weapons after the crash. This is an indisputable fact already because the deuterium/tritium reservoirs in the tail sections of the four weapons broke off on impact and were recovered close to the impact point.

We can provide a clear answer: there is no bomb, there was no bomb, and the Americans were not looking for a bomb.

We have found strong indications that all four primaries were destroyed in conventional explosions on impact. The primary is the first stage of the bomb.

The plutonium in the primaries of all four weapons was dispersed in particulate form in the explosions and the ensuing fire.

This is in all important respects consistent with what happened in the low-order explosions of the high explosives in two of the bombs in the Palomares accident two years earlier, and equally consistent with the consequences of this for the secondaries and for the character of the dispersed active particles at Palomares.

We have argued that all four secondaries were destroyed as well, but not in all cases with the same devastating consequences for these sections as for the primaries.

About the plutonium

Thus far there has been some public disbelief that all four primaries actually exploded. This disbelief was caused by the idea of a discrepancy between the 24 kg of plutonium thought to be needed to reach criticality in the four primaries taken together, and the approximately 6 kg that the authorities claimed to have been involved in the accident.

Skeptics among the public would say that either all four primaries did not explode (leaving the possibility of a ‘missing bomb’) or the supposed 24 kg had not been accounted for properly (meaning that the contamination was worse than admitted).

We believe that, after several decades of discussion, we have established that the amount of plutonium 239 dispersed as very small particles in the conventional explosions of the weapons roughly corresponds to the amount of plutonium 239 actually contained in the weapons to begin with.

This is a breakthrough in the investigation of the accident, although achieving it is certainly not rocket science. Its importance lies in the fact that the agreement between the figures helps to remove grounds for doubting the official explanations as to what happened and may mark a new beginning in rebuilding confidence on this account. We cannot, however, provide a final material balance. That is a task for the authorities and the natural sciences.

This finding, simple as it is, was one of the Eureka! moments in our investigation. And, as sometimes happens, the solution was lying right on the doorstep. After weeks of consulting the literature and the experts in various fields without result, we finally turned to the disarmament literature.

As a reference value, this gave a figure of roughly 2 kg of plutonium 239 per weapon. After that, several other pieces of information pointing in the same direction began to surface.

The jewel in the crown in this respect was two lines with three figures in the hand-written minutes of a meeting in Washington held on 5 February 1968. On the basis of these two lines, we arrived at a figure of roughly 7.5 kg plutonium for the four weapons.

In the 1950s and 1960s, the primary pits consisted of large amounts of uranium 235 and relatively small amounts of plutonium 239. The standard reference value for plutonium 239 in the weapons of that period is about 2 kg. In later weapons, when the amount of uranium in the pit mix was reduced, the minimum amount of plutonium grew to perhaps 4 kg, a figure for modern weapons that was declassified by the U.S. authorities in 1994.

About the underwater search and the ‘missing component’

No nuclear weapons have been left on the bottom of the sea in Thule, nor was any secondary left in the sea. The arguments are listed in the summary of evidence, among them the fact that the weight of nearly three secondaries (94%) was recovered and shipped to the U.S. Many of the secondary pieces were small and unnumbered and were found widely scattered on the ice.

Reaching a figure of 94% by weight for three secondaries seems improbable under the circumstances if pieces from only three weapons had been collected. It is much more likely that this figure was reached by recovering pieces from all four secondaries.

We believe that by April 1968 the U.S. authorities already had a very good idea of what had happened to all four secondaries. If not, it would be incomprehensible how they could ask Sandia Corporation to establish trajectories in the water of Bylot Sound for one special, extremely well-defined weapon component − only one, and certainly from a secondary. This is the second jewel in the crown of the investigation.

We believe that what the Americans were looking for was the marshal’s baton, the fissile core of a secondary, often referred to as the spark plug. The object was cylinder-shaped with rounded ends. Its drag coefficient was calculated by Sandia Corporation to be 0.6 head on and 1.0 side on. It could have been a massive rod, but it is far more likely that it was a pipe with sealed ends. The sources provide ample evidence that such pieces were recovered on the ice in February and March 1968, and that the hunt for the remaining pieces continued to the end of the operation in August 1968.

There is a solid body of evidence that the marshal’s baton contained uranium 235. We believe that the documents refer to the marshal’s baton as the ‘secondary pit’ and the ‘oralloy pit’, although no experts seem to remember or know this terminology. If we suppose that the marshal’s baton contained 8 kg of uranium 235, it would have had a volume of roughly four decilitres. A cylinder with such a volume could, for instance, be 50 centimetres long with a diameter of 3.3 centimetres, or somewhat thicker if it were a pipe, for instance, 5.4 centimetres with a wall thickness of 5.5 mm.

This is a rather small object to find on the sea bottom, especially when we remember that it could have broken to pieces and might be located among thousands of other pieces of debris. Yet, it is bigger than a spark plug in a car. We have chosen to call it the marshal’s baton instead. The size fits this description better.

That an object of this size was indeed what the American Star III submersible was looking for is demonstrated in the video footage from the dives where the claw can be seen recovering an object fitting this description. On closer inspection, the object apparently turned out not to be the sought-after prize.

Finally, we must not forget that the decision-makers and search teams could not be sure that the sought-after component had survived the crash. One would assume that they kept an open mind for the possibility that it had been blown to pieces or completely destroyed in some other fashion.

The BBC has exaggerated the confidentiality of the underwater operations. These operations were carried out under an agreement reached in a number of Danish-U.S. meetings. H.H. Koch, the Chairman of the Danish Atomic Energy Commission, understood perfectly well that the bottom survey was not a major operation.

We can return to our previous answer in a more elaborate form: there is no bomb, there was no bomb, and the Americans were not looking for a bomb. They were looking for the marshal’s baton. Nor were there any whole pieces of any of the primary stages, nor any whole ones of any secondary stage, nor any tail section left behind.

This may be the place to quietly observe that the Danish foreign minister’s 1987 statement about the dives, reproduced in the introduction, was absolutely correct.

To repeat, the Americans were not looking for a bomb but for a weapons component, almost certainly a uranium 235 fissile core from the secondary stage of a weapon. They were probably not at all sure if it had actually fallen to the bottom and in what state, nor whether it still existed. Crumbling of uranium metal in water has been observed in many studies. If there were something to be found, they did not find it in the last days of August 1968.

A comparison with the search for the missing bomb in Palomares two years earlier deals a final heavy blow to the idea of a nuclear weapon on the bottom of the sea in Bylot Sound. It is obvious that the sea bottom search in Thule had an infinitely lower priority than the successful search in Palomares.

We derive this conclusion from an analysis of the discussions in Washington, as well as from the very different dimensions of the respective underwater operations. The extensive side track sonar scans in Bylot Sound in 2003 performed by the Geological Survey of Denmark and Greenland showed no signs of debris from the crash, only an old iron frame. The jewels were in the archives, not in the sea.

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