Sleeping horror

This may look like a perfectly ordinary hot water tank. The builders who found it thought that's what it was, at first. The first clue as to its true nature was the lack of water pipes leading to or from it, or any sign that there had ever been any. When they realised that there seemed to be a long-disconnected telephone cable leading to the device they, very sensibly, became alarmed and called the police.

It is not, of course, a hot water tank: it is a lightly-modified B43, apparently dialled to its maximum yield of approximately 1Mt. The device seems to have been intended to be triggered in the event that it did not hear a dial tone on the phone connection over a period of a little longer than a week: fairly obviously it was intended that it should detonate in the event of a successful invasion when, either through enemy action disrupting the telephone network or intentionally on the part of the remaining defenders, its inverse dead-man's handle would trigger it.

In the case of this device the clock mechanism appears to have stuck at some point thus causing it, against its designers' intentions, to have failed safe. In any case various components of the device have decayed over time and with lack of maintenance and it is mostly safe now: even if it could still be triggered the yield would be only a few tens of kt at most. More likely it would fizzle, dumping radioactive debris over a few hundred square metres.

No record of the existence of the phone connection exists. It is to be hoped that this was a single, forgotten device and that more are not still waiting, checking daily for dial-tone on phone connections no-one now remembers exist.