Re: Urban legends - plutonium in exploded rocket

["Busby, Bruce" <bab1303@doh.wa.gov>]

Hi all... 

was doing some research and thought I would see about adding my two cents 
worth to the Urban Legends threat, dead as it is... 

Here is some information about all of the prior RTG accidents.

Since 1961 the United States has launched 25 spacecraft with radioisotope 
thermoelectric generators (RTG) on board. Three of the missions failed, 
and the spacecraft reentered Earth's atmosphere. However, none of the 
failures were due to problems with the RTGs.

In 1964, a TRANSIT 5BN-3 navigational satellite malfunctioned. Its single 
RTG, which contained 2.2 pounds of plutonium fuel, burned up during 
reentry into Earth's atmosphere. This RTG was intended to burn up in the 
atmosphere in the event of a reentry.

In 1968, a NIMBUS-B-1 weather satellite was destroyed after its launch 
vehicle malfunctioned. The plutonium fuel cells from the spacecraft's two 
RTGs were recovered intact from the bottom of the Santa Barbara Channel 
near the California coast. According to National Aeronautics and Space 
Administration (NASA) and Department of Energy (DOE) officials, no 
radioactive fuel was released from the fuel cells, and the fuel was 
recycled and used on a subsequent space mission. The intact fuel
cells were recovered in an underwater recovery operation.

In 1970, the Apollo 13 Moon mission was aborted due to mechanical 
failures while traveling to the moon. The spacecraft and its single RTG, 
upon return to Earth, were jettisoned into the Pacific Ocean, in or near 
the Tonga Trench. According to DOE officials, no release of radioactive 
fuel was detected.

Since 1965, when RTGs were redesigned to prevent the release of 
radioactive material rather than disperse it, there have been two 
accidents (the 1968 NIMBUS-B satellite launch and 1970 Apollo 13 lunar 
module reentry) where RTGs were on-board spacecraft. Neither of these 
accidents were caused by the RTGs, and in both accidents, the RTGs 
responded to the accident conditions as their design and testing had 
predicted, fully containing their plutonium. In fact, after the Nimbus B 
accident, as noted, the plutonium fuel was recovered, reprocessed and 
reused.

NASA has 20 some space missions planned in the next few years. None will 
have the RTG units, though 2 may have RHUs (small nuclide heaters with 
2.7 g PuO2) to help keep instruments warm. Over the next 15 years or so, 
there are some 8 potential missions that may use RTGs (if funded) and 3 
potential missions that might use RHUs (also if funded). Most look like 
there are heading to Jupiter and Saturn's moons, or Mars. 

REF:  Allen Li, Associate Director Defense Acquisitions Issues.  "Space 
Exploration: Power Sources for Deep Space Probe." GAO/NSIAD-98-102, 
Report to The Honorable Barbara Boxer, United States Senate. 1998.

REF: NASA Facts: Future NASA Spacecraft: Solar Arrays, Batteries, and 
Radioisotope power and Heating Systems. NASA, 1998.



--------------------------------------------------------------
Bruce A. Busby    -     Radiation Health Physicist
W- bab1303@doh.wa.gov      H-babusby@aol.com
Rad Prot. Div. - Dept. of Health - Washington State
7171 Cleanwater Lane, Bldg. 5   Olympia, WA  98504
---------------------------------------------------------------

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