GCHQ dispose of hard disks by dipping into nuclear reactor (allegedly)

I just purchased Net Spies by Andrew Gauntlett from the local Oxfam bookshop. Published in 1999, it covers various issues about Internet privacy, including encryption. What made me buy the book, however, was not the exciting prospect of a pop-sci treatment of the perils of "The Net", but the following anecdote:

Paul Baccus, a technical engineer with an Oxfordshire based data-recovery firm, describes an extreme method of data-erasure: when GCHQ decommission old computers, they adopt a unique and somewhat extreme practice to ensure that no data can ever be recovered from discarded disks. Armed police escort unwanted GCHQ tapes and hard disks from GCHQ directly to the nuclear power station at Sellafield. There, they are dipped into the nuclear reactor, where the high levels of radiation permanently destroys the data. It also renders the remains of the disk highly radioactive further discouraging any attempt to recover residual data.

Yikes! But, hmm, I have to admit, I'm fairly skeptical about this. I mean, the expense of lugging the disks and tapes all the way over to Sellafield with armed police etc -- why not just blow the tapes up on site or something? I do get the feeling Net Spies might be a little flakey on that old minor issue of factual accuracy; I skimmed the book and found the following clanger:

A mechanical device known as the `Enigma machine' encoded the German's orders...Alan Turing, mathematician and father of modern computing, finally cracked the code in 1941 by constructing the world's first computer, which was named `Colussus'.

Well, it was called "ColOssus", wasn't constructed by Turing, and wasn't built to crack Enigma, but the thought was there, I suppose. (MSN Encarta have a similar mistake in their "Computer" article, so perhaps we can be forgiving).

If anyone has any information on GCHQ's methods of data erasure, delusional or otherwise, do let me know (assuming it's unclassified, of course, *cough*).