Background:
One of the major elements of Lazar's story, and one he's repeated several times, is that he was told he was hired as a "replacement" for another scientist that had been killed in a major explosion. As the story goes, this unlucky fellow, along with a few others, were done in when they attempted to cut into an operating reactor that had been removed from one of the discs.
Lazar says he was told this had occurred in an underground shaft or tunnel at the Test Site where the reactor had been taken for this particular "experiment".
In George Knapp's KLAS-TV special when he first identified Lazar in November of 1989, Knapp stated (it is assumed with Lazar's concurrence) "There was an accident he says, back in April 1987. An accident that was passed off as an unannounced nuclear test."
In "Alien Contact" Lazar said in a March, 1990 interview, the blast occurred in May of 1987 in a vertical tunnel, and took out the first door, killing 3 people. It also destroyed a few hundred thousand dollars of monitoring equipment.
In "UFOs and The Alien Presence" Lazar said in a September, 1990 interview that the blast had blown the blast door off into the monitoring area and he thought the blast's size was in the 20 kiloton range.
Analysis:
The story told by Lazar is very consistent, with the exception of the dates. The inconsistency of the dates, while not desirable, is probably not unreasonable given Lazar's memory.
So what do the Test Site records have to say about this?
Per DOE records, there were three announced tests in April, 1987:
April 18, 1987 Code Name Delamar 20-150 kilotons
April 22, 1987 Code Name Presido < 20 kilotons
April 30, 1987 Code Name Hardin 20-150 kilotons
These tests were definitely known in advance as there was the usual contingent of protestors at the Test Site gate.
There were no announced tests in May of 1987 according to the DOE.
What about unannounced tests? After all, that's what Lazar said this incident was passed off as. It certainly wouldn't have been expected.
On December 7, 1993, as part of its new openness, the DOE released a listing of ALL previously unannounced tests at the Test Site, going back to 1963. There were 204 of them. Not one of them occurred anytime in 1987. As part of its announcement, the DOE also said there were no other announced tests. Th-th-th-that's all, folks....
So, there were no unannounced nuclear tests that support Lazar's story, and the announced tests were known in advance so they don't make sense as an explanation.