Kiwi Test

January 12th, 1965

The Kiwi TNT Effluent test explosion at the Atomic Energy Commission (AEC) test site at Jackass Flats, Nevada occurs on January 12, 1965.  Part of a rocket’s nuclear core is intentionally vaporized so that scientists can study the behavior of the reactor and the environmental effects of the radiation.   The concept of the test is to study what might happen if a nuclear rocket engine were to accidently explode. (+) (+)

Destruction_of_KIWI_Nuclear_Reactor_-_GPN-2002-000145  A photograph of the Kiwi TNT Effluent test explosion at Jackass Flats, Nevada.

The test was designed so that all winds from the test site would be from the northeast, thus the radioactive cloud created by the test would blow to the southwest from the test site for a distance of 200 miles toward densely populated areas of southern California.  The radioactive cloud was tracked by U.S. military aircraft.  Increased radioactivity was observed in Barstow, California, San Bernadino, California, Los Angeles, California, and San Diego, California.


• The Kiwi Transient Nuclear Test involved a controlled nuclear excursion resulting in partial vaporization of the reactor core.  This test created a low radioactive plume (low in radioactivity) that was detectable far off-site.  The U.S. Public Health Service monitored the cloud to beyond 200 miles downwind, extending to Los Angeles and the Pacific Ocean. (+) (+)

• The “Environmental Effects” of the Kiwi-TNT Effluent — The Kiwi Transient Nuclear Test (Kiwi-TNT) was a controlled excursion to vaporize a significant portion of the reactor core.

The test studied environmental effects of the radioactive materials released.  The U.S. Public Health Service (USPHS) monitored the neighborhood and collected milk samples in southern California to beyond 200 miles downwind.  The course of the effluent cloud was tracked by aircraft.  From 5 to 20% of the reactor core was vaporized with approximately 67% of the products from about 3 x 10^20 fissions released to the effluent cloud.

USPHS provided offsite radiation surveillance by aerial tracking of the effluent cloud, monitoring radiation dosage of the off-site population, and collecting environmental samples in southern Nevada and California.  Following the test milk samples were collected in 14 locations in southern California.  The milk sampling program continued for approximately a week.

Vegetation samples were obtained.  Aircraft tracked the effluent cloud from Death Valley to over the Los Angeles area, terminating contact over the Pacific Ocean.

The weather at the time of the test fulfilled the desired conditions.  The winds were northeasterly at all levels, ranging from 14 to 27 knots.  The Kiwi-TNT reactor was “exploded” in the sense that it was a violent disruption and dispersion of an originally intact object.  It blew up in an unusual fashion.  Because the Kiwi-TNT was a unique, controlled simulation of a phenomenon frequently called a maximum credible reactor accident, there was great interest in the radiological characteristics and effects of the effluent many miles from the test point.

The USPHS documented the effects of the long-range effluent cloud on the people and agriculture downwind.  Personnel observed the radioactive cloud shortly after it reached California and again as it reached the Pacific Ocean.  At 11 hours 20 minutes after the Kiwi-TNT event aircraft again attempted to locate the effluent cloud.  Positive signals were received over the ocean from Los Angeles to near Santa Barbara.  Several hours later aircraft returned to the previous search area and again detected weak, but positive signals.  A few days after the Kiwi-TNT event, Public Health officials observed increased radioactivity in routine air samples from the Barstow, San Bernardino. Los Angeles, and San Diego, California, areas.

Page #215:  Full Text:
Ideas about radiological warfare surfaced even before the U.S. began its atomic bomb program. Key atomic scientists Ernest O. Lawrence and Arthur Holly Compton proposed a top priority program to develop radioactive
weapons in 1941.  An atomic bomb program was actually given a lower priority at that point, in part because it was far more complex than producing fission products for use on a battlefield or an enemy city.
While most attention soon shifted to the bomb program, anxieties persisted that Germany might develop  radiological weapons for use against American or English cities. The Manhattan Project even sent radiation detection instruments to Washington, New York, Chicago, and other cities to prepare for such an attack.
Serious consideration was given to radiological warfare after the war.  There was concern that a foreign power, frustrated in its attempt to develop an atomic bomb, might instead turn to radiological warfare.  In 1947, the Armed Forces Special Weapons Project of the Department of Defense (DOD) asked the AEC to form a committee to study the subject.