Radiation hazard?

While looking for something else in the KZLA NOTAM current as
of Wed, 15 Sep 2004 17:53:00 GMT, I found this interesting
warning:

FDC 4/5471 - CA.. POINT MUGU NAS, CA. RADIATION HAZARD TO
AIRCRAFT EXISTS WITHIN A 1.5 NM RADIUS OF 340555N/1190700W.
THE AREA IS HOT CONTINIOUSLY FROM SFC TO 8000 FT AGL.
AIRCRAFT WISHING TO TRANSIT THE AREA SHOULD CONTACT THE
APPROPRIATE ATC AGENCY FOR THE STATUS OF THE AREA PRIOR TO
ENTRY OR TRANSIT. WIE UNTIL UFN

I assume the "radiation hazard" is some sort of RF emanation
that could mess up on-board electronics, but the extremely
short range is curious. Street Atlas 2005 shows the coordinates
as lying west of the intersection of Beach Road and 19th Street
in Pacific Missile Test Range facilities, Port Hueneme.

Any idea what this hazard might actually be?