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01/14/2004
Hot Stuff
Last week, I discussed how detecting radiation in the form of
gamma-rays from cosmic explosions might confirm an exotic
theory known as loop quantum gravity. I didn’t know then that
radiation would be the subject of this week’s column. However,
three radiation-related items seem to mandate what follows.
Let’s begin with the orange alert. When the weather is cold or
rainy, I join my wife in walking at our local mall, which allows
registered walkers in at 7:30 AM before the stores open. The
orange alert prompted the mall management to suspend this
privilege. Now we have to put off our walking until 10 AM, thus
killing most of the morning.
The presence of bomb-sniffing dogs and police armed with
automatic weapons either makes one feel more safe or more
concerned, depending on one’s emotional makeup. Suspension
of the walking program prompted a news item in our newspaper,
the Star Ledger, and my wife and some of our co-walkers were
featured in a TV news report on Public TV Channels 13 in New
York and NJN in New Jersey. My wife’s few seconds of fame
came as she was shown briskly walking past the camera.
What does all this have to do with radiation? Perhaps you know
that radiation detectors were used during the New Year’s Eve
Times Square celebration to ferret out any “dirty” bombs that
might be used by terrorists. Well, last week at our mall a
radiation detector did pick up radiation, causing the police to
clear out the Legal Seafood restaurant and the adjacent Tiffany’s
(it’s a upscale mall), causing considerable confusion and concern
among customers and employees. Fortunately, the radiation trail
in this case led not to a dirty bomb but to a person under some
sort of radiation treatment for a medical condition.
My wife informed me of this incident when I returned home
from attending a lecture, after which I talked with a researcher
who said she was working with “depleted uranium”. This
sounded like a dicey sort of material to be working with but she
assured me that it was not very radioactive. Actually, when I
was in graduate school at the University of Pittsburgh one of my
projects in an inorganic chemistry course was to prepare uranyl
acetate, a compound of uranium. This was in the years following
the end of World War II and the atom bomb, which employed the
uranium isotope U-235. Uranium was an exotic material and I
gave little thought to its radioactivity.
Looking back, I’m assuming that the uranium in my compound
at Pitt was natural uranium, which is 99.3 percent U-238 and 0.7
percent U-235 with a trace of U-234. What is depleted uranium?
It’s uranium that has been processed to remove U-235 for either
nuclear weapons or nuclear power. All three of these isotopes
are radioactive but they have widely different half-lives. Take
U-238 with its half-life of 4.5 billion years, roughly the age of
the earth! This means that 4.5 billion years from now half of
today’s U-238 will still be around. Conversely, it means that at
any one time not very much of it is giving off any particles – the
level of radioactivity is low. U-234, on the other hand, has a
half-life of only 25,000 years. This is why there’s so little left in
natural uranium – it decays relatively rapidly. U-235 is in
between with its half-life of about 700 million years. (I found
these figures on the Argonne National Lab Web site.)
Depleted uranium has less than the 0.7 percent of U-235 found in
natural uranium so you might think it would be a relatively
benign material. However, type “depleted uranium” into your
search engine and you’ll come up with a slew of Web sites
decrying its use. The outcry is prompted by the depleted
uranium used in armor piercing armaments and in missile-
resistant armor for tanks and other military applications. The
debris of war in Bosnia, Iraq, etc. includes depleted uranium
from the military operations. Claims abound that cancers have
been caused by depleted uranium. Uranium isn’t just
radioactive, it’s also a heavy metal and heavy metal poisoning is
a possibility. (Uranium is so heavy that it apparently has been
used to weigh down the nose of certain airliners.)
All these concerns, whether or not justified (I’m making no
judgment here), certainly add to the stresses of modern living. It
doesn’t take depleted uranium to cause stress, however. The
cloudy, rainy weather in Tacoma makes it the “most stressful
city” in America, at least according to a TV news report I saw
last week. I didn’t catch who or what group came up with “the
most stressful cities” and was not surprised to see New York
ranked as the fifth most stressful. But what really drew my
attention were the “least stressful” cities. The Harrisburg-
Lebanon-Carlisle metropolitan area in Pennsylvania was tied
with the Albany-Troy-Schenectady area the least stressful. I
grew up in Mechanicsburg, which is between Carlisle and
Harrisburg. At my high school reunions, I’ve often thought how
low key the atmosphere was.
Where does radiation come into the picture? That Harrisburg-
Lebanon-Carlisle area was the most stressful area in the country
25 years ago. The day I heard about depleted uranium and mall
radiation, I was reading my Winter 2004 issue of the Dickinson
Magazine. Dickinson College, my undergraduate alma mater, is
in Carlisle. On March 28, 1979 the nuclear reactor at Three Mile
Island (TMI) suffered a meltdown resulting in the release of
radioactive material only 22 miles from Carlisle. The magazine
marked the 25th anniversary of TMI with two articles by senior
editor Sherri Kimmel on the incident, its effect on the Dickinson
community and Dickinson’s involvement in studying the
reactions of residents of the area to the accident.
I had no idea that the incident, the worst commercial nuclear
accident in the U.S., had caused such concern in Carlisle. An
estimated 65 percent of the students fled the campus for home.
Five or six professors also left, one never to return (he was
brought up near the infamous Love Canal and I guess was totally
spooked). The president of the college canceled the next week’s
classes, only the tenth time that had happened in the over 200-
year history of the college. Three Mile Island marked the end of
building nuclear power reactors in the U.S.
Two of the professors who stayed were physics professor
Priscilla Laws and her husband Ken, also a physics professor.
(In my column of 12/7/1999 [see archives], I wrote about Ken
Laws’ work on the physics of ballet dancing.) Priscilla and
another physicist, John Luetzelschwab, made measurements of
the radiation on campus and on soil from the latter’s garden,
located only two miles from TMI. Forty students joined in the
analysis of the data. Laws and Luetzelschwab briefed the public
daily on their findings, which showed no significant rise in
radiation levels but there was one troublesome result. There was
a heavy rain after the TMI accident and the level of radon gas
doubled. They had to reassure the community that this was a
normal occurrence after a heavy rainstorm. Residents in Carlisle
paid close attention to the presence of Priscilla’s Toyota station
wagon as assurance that she hadn’t fled and that all was well.
Another professor who stayed was T. Scott Smith, whom we met
at one of my class reunions. Smith had our Lamb guy, Harry
Trumbore, a fellow Dickinson alum, in one of his classes. In
place of a written final exam, Smith had Harry draw a 4-page
cartoon related to the history of science. Harry’s caricature of
Smith was used instead of a faculty photo in the yearbook!
In addition to the efforts of the physics professors and students, a
number of professors and students in the social sciences set out
to study specific reactions of the community. They hoped to
study the roles humor, religion and culture played in coping with
the stress at the time. There were 400 interviews, with the
promise that the interviews wouldn’t be made public for 25
years. The 25 years are almost up and plans are to place some of
the 40 linear feet (55 boxes) of interviews and other materials
related to TMI on the Web site www.ThreeMileIsland.org in
February.
Well, we’re back to yellow and the mall is now open to us
walkers at the usual early hour. And I was just getting used to
enjoying sleeping for an extra 45 minutes or so.
Allen F. Bortrum
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