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RE: Nuclear-powered spacecraft plan feared



John, et al.,



I believe the event to which you refer was Cosmos 954, a Be-moderated

fission reactor fueled with HEU-Mo alloy (100 kWt; 10 kWe) (see

http://gamma.gsc.nrcan.gc.ca/images/cosmos.jpg).  Cosmos 954 reentered

the earth's atmosphere on January 24, 1978 (I remember this fairly well)

on a trajectory that passed over the Northwest Territories, starting

over the Great Slave Lake and proceeding east-northeast (see

http://gamma.gsc.nrcan.gc.ca/images/mlorbit.gif for final orbits.)  A

map of the approximately 600 km long debris field is shown on

http://gamma.gsc.nrcan.gc.ca/images/mlpath.gif.



Response to the reentry was a joint Canadian-US operation (Operation

Morning Light).  US response assets included a couple of Nuclear

Emergency Search Teams (from then ERDA).  This was a rather unpleasant

operation, since it involved debris mapping and recovery in some rather

nasty weather (-40 on either scale - see

http://gamma.gsc.nrcan.gc.ca/images/rec3.gif).  Keeping radiation

monitoring equipment operating in such extreme temperatures proved to be

a significant challenge.



More than 50 large fragments including bits of steel and Be plates and

rods with near-contact dose rates ranging from 0.006 to 2 Gy/h were

subsequently recovered.  The highest measured near-contact dose rate was

5 Gy/h.  Approximately 65 kg of debris, a very small fraction of the

several ton mass of Cosmos 954, was recovered.  Fuel particles (0.1-1 mm

diameter) ranging from 200-5000 MBq in activity were recovered.  Dose

rates measured at 1 meter ranged from 0.1 - 1 mGy/h. Approximately 4000

fuel particles were recovered, representing approximately 0.1% of the

particles estimated to be dispersed from the reentry.



High altitude air sampling measure measurements revealed the presence of

enriched uranium at an altitude of approximately 40 km at 65 degrees

north between June and September 1978.



There's a write-up on the LLNL web site (see

http://www.llnl.gov/timeline/1970s/pdfs/1978.pdf)  I also recall

perusing a beautiful color publication by ERDA that showed how NEST

reconfigured its equipment for arctic operations, as well as photographs

of some of the larger debris fragments.  Alas, I do not have a copy of

that one.



There's also a brief entry on a DND/Canada Forces web site (see

http://www.dnd.ca/site/fourth_dimension/2002/jan02/jan25_fd_e.htm) and a

PDF bilingual reprint from "The Maple Leaf" on

http://www.dnd.ca/site/community/mapleleaf/vol_5/vol5_03/vol5-03pg14-15.

pdf.



Also see "Emergency Preparedness for Nuclear Powered Satellites", OECD

1990, which summarizes the following 6 malfunctions/reentries:

	-	Transit 5BN-3 (SNAP-9A RTG), 1964

	-	Nimbus B-1 (SNAP-19 RTG), 1968

	-	Apollo 13 (SNAP-21 RTG), 1970

	-	Cosmos 954 (nuclear reactor), 1978

	-	Cosmos 1402 (nuclear reactor), 1983

	-	Cosmos 1900 (nuclear reactor), 1988



The SNAP-9A was designed to vaporize on reentry and dispersed 630 TBq of

Pu-238 into the atmosphere at 120 km altitude.  The SNAP-19A was

recovered from the Santa Barbara Channel and the Pu-238 microspheres

were subsequently reused.  The RTG-21 from the aborted Apollo 13 mission

was designed to survive reentry and is lying at a depth of 6000m in the

Tonga Trench.



I hope this contributes to the thread.  Obviously, the RTGs used for the

Galileo and Cassini deep space probes have substantially larger

inventories of Pu-238



George J. Vargo, Ph.D., CHP

vargo@physicist.net

610-925-1954

610-925-5545 (fax)





-----Original Message-----

From: owner-radsafe@list.vanderbilt.edu

[mailto:owner-radsafe@list.vanderbilt.edu] On Behalf Of John Johnson

Sent: Thursday, February 06, 2003 7:55 PM

To: Franz Schoenhofer

Cc: Radsafe (E-mail)

Subject: Re: Nuclear-powered spacecraft plan feared





Franz



If its the one I remember, it occurred in the seventies. The Pu was

Pu-238 and it was spread over a large area in the NW Territories. RP

staff from AECL/CRNL were sent to monitor the levels and only found a

slight increase in the total Pu levels, most of which was PU-239 from

fallout. _______________________ John R Johnson, PhD

idias@interchange.ubc.ca



----- Original Message -----

From: "Franz Schoenhofer" <franz.schoenhofer@CHELLO.AT>

To: "Grimm, Lawrence" <LGrimm@FACNET.UCLA.EDU>; "Radsafe (E-mail)"

<radsafe@list.vanderbilt.edu>

Sent: Thursday, February 06, 2003 2:03 PM

Subject: AW: Nuclear-powered spacecraft plan feared









 -----Ursprüngliche Nachricht-----

Von: owner-radsafe@list.vanderbilt.edu

[mailto:owner-radsafe@list.vanderbilt.edu]  Im Auftrag von Grimm,

Lawrence

Gesendet: Donnerstag, 06. Februar 2003 19:34

An: Radsafe (E-mail)

Betreff: RE: Nuclear-powered spacecraft plan feared



Radsafers:



A radsafer sent me the following (slightly edited), and my response to

him follows.  I am seeking your comments/advice on the assumptions I am

making regarding a Pu accident.

--------------------------------------------------------------------



Lawrence and Radsafers,



I would like to remind all of you, that some decades ago, a satellite

with a Pu-238 battery on board was vaporized on its reentry into the

atmosphere. So this could be a good hint to the "hazards" of plutonium

batteries from spacecrafts or satellites. Unfortunately I do not have

any literature at hand, but I think, that some RADSAFErs will remember

this event. One consequence is for sure: In spite of the Pu distributed

mankind has not been exterminated!



Best regards,



Franz







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