THERE are some events in our modern history that become known by one word. Dunblane. Hungerford. Hillsborough. Zeebrugge. Munich. Llandow. Kegworth. These place names are forever associated with disaster and horror, with grief and pain, but also with courage and the triumph of the human spirit. So it is with Aberfan. Fifty years ago tomorrow a fate so awful as to be almost unimaginable befell a village in the South Wales coalfields. A generation was wiped out shortly after 9.