Official schematics for a “workable” atomic bomb appeared on Wikileaks last week, purportedly depicting the “Fat Man” weapon detonated over the Japanese city of Nagasaki.

The schematic, a “crude” British description of the famous “Fat Man” device developed at Los Alamos laboratories, was part of the declassified-then-retracted Penney Report, released under the UK Public Records Act.  However, the UK retracted the document from public access in 2002.

Wikileaks claims the medium-quality scan of a 1947 drawing is still a public record. The site notes that despite having its access conditions changed to the custody of the Ministry of Supply, nobody from the government has tried to contact anyone already in possession of the file, known as UK Public Record Office File AVIA 65/1163 “Implosion.”

“It should be observed that Penney's description and discussion of development are no more revealing than descriptions of the United States' first implosion bomb that have been publicly available for many years, and in fact are less precise than other descriptions that are now available,” reads the analysis, which appears to have been originally posted at nucelarweaponsarchive.org. The schematic, part of the 1947 Penney Report compiled by elite British scientist William G. Penney, who served on the Manhattan Project, is described as “the oldest material in the file” and was written “before any actual bomb development work had been undertaken in the UK.”

An original text transcription of the Penney Report depicts a Britain deep in the development of its own nuclear program: a chart in Appendix M classifies bomb development into 11 categories, and it lists only two that Britain could “go straight ahead and make.” Other categories, including the bomb’s Plutonium core and detonation fuse, cite everything from inexperience to difficulty in acquiring materials as bars to progress – all of which seemed to be defeated by 1952, when the UK successfully carried out its “Operation Hurricane” at midnight, October 3.

“This diagram is not really a secret to foreign intelligence services,” reads the WikiLeaks analysis, “nobody is going to be surprised by this design, just by the fact that it’s appeared in public.”

“Open sources have speculated on these matters for a long time (see Nuclear Weapons Design article in Wikipedia), and this just confirms that they were right,” it adds.

It appears that Wikileaks is comfortable posting the plans: “The real problem about building one of these designs is the rarity … of plutonium and polonium, as well as the ability to fabricate sophisticated high explosives to exacting specifications,” it says. “We’re not talking about IEDs here: to build a nuclear weapon requires a state.”

As worrisome as the phrase "leaked nuclear bomb schematics" sounds, there is little harm in the one posted on Wikileaks.  At least, there's nothing in the schematic that isn't discussed in high school physics classes across the world.

But Wikileaks stirs up another question in its most recent leak controversy.  Last month Wikileaks unveiled a series of documents implicating the Julius Baer Group of fraud.  While the bank was universally blasted for attempting to get these documents removed from Wikileaks, the jury is still out on how the public will accept leaked nuclear secrets.