Re: Nuclear-powered spacecraft plan feared

["Jerry Cohen" <jjcohen@PRODIGY.NET>]

Perhaps another perspective on plutonium hazard might be useful:

During the period of atmospheric testing of nuclear explosives, over 10 tons

of plutonium were released to the atmosphere in fine particulate form. Fine

particles do not readily settle from the atmosphere regardless of their

atomic wt. or density. As a result, these fine plutonium particles were

spread over much of the earth's surface and can be found in detectable

quantities almost everywhere. It is reasonable to assume that during this

period significant amounts were also inhaled by people. In the decades

following, there has been no increase in  lung cancer incidence, other than

can be accounted for due to smoking.

Relatively, any quantity of plutonium that could conceivably have been

released from any space vehicle could be considered inconsequential.





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

From: Grimm, Lawrence <LGrimm@FACNET.UCLA.EDU>

To: Radsafe (E-mail) <radsafe@list.vanderbilt.edu>

Sent: Thursday, February 06, 2003 10:33 AM

Subject: 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. Please comment privately. Thanks. -lg

>

> Larry,

>

> Normally I don't respond to posts on radsafe, but your letter to the SF

> Chronicle reporter has me worried.  We as a health physics community need

to

> respond to outlandish statements voiced by members of the anti-nuclear

crowd

> with factual and reasoned scientific argument.  Your statements on Pu

> exposure were not.

>

> The most likely uptake method in such an accident scenario or for that

matter most

> any scenario apart from eating Pu particulate or sucking on a contaminated

> finger is inhalation of suspended Pu oxide.  Unlike Natural U (or even

> weapons grade U) inhaled Pu (239, 240 or 238) is much more of a

radiological

> hazard than chemical because of its specific activity.  A small amount of

S

> or M class Pu can cause a very large committed dose to the lungs based

upon

> the ICRP 66 models.  - CP

>

> My Response.

>

> CP: I appreciate the advice.  I fully agree with your assessment of the

potential lung dose. I would be interested if you have info to the contrary,

but it is my understanding that PuO does not stay suspended in the air very

long due to its large atomic weight.  In an accident scenario, unless the

person is near the location, the risk of inhalation drops dramatically with

distance.  I am also making the presumption in an accident with a rocket,

e.g. the shuttle or other space craft, that it would occur at high altitude.

As a result, any created PuO would disperse over a huge area, with a

lessening of inhalation risk as it disperses.  In a rocket accident, the

better percentage of the Pu would remain in the debris as particulate

material, with the subsequent risk of ingestion primarily being particulate

mishandling, e.g. sucking on a contaminated finger.

>

> It is very tough to simplify these sorts of assumptions in statements to

the public.  Frankly, if I said all of the above to a reporter, the reporter

would tune out immediately.  When I make simplified statements to reporters,

I always have a defensible position ready in case I am challenged.   - Larry

Grimm

>

> Larry Grimm, Senior HP

> UCLA EH&S/ Radiation Safety Division

> * lgrimm@admin.ucla.edu   Phone:310/206-0712   Fax: 310/206-9051

> Cell: 310/863-5556  Pager:1-800-233-7231ext93569

> * On Campus: 501 Westwood Plaza, 4th Floor, MS 951605

> * Off Campus: UCLA Radiation Safety Div, 501 Westwood Plaza 4th

> Fl, Box 951605, Los Angeles, CA 90095-1605

> * If this email is not RSD business, the opinions are mine, not UCLA's.

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