SAFETY OF SOURCE TRANSPORTS IN QUESTION AFTER IRIDIUM LEAK
NUCLEONICS WEEK - January 17, 2002 11
Federal Express is expected to install radiation monitors at
its European air cargo hub near Paris, in light of tentative
conclusions by French rad protection authorities that handlers
of radioactive packages could receive doses over the allowed
public limit of 1 milliSievert (10 millirem) per year, according
to experts in Paris.
A FedEx spokesman said Jan. 16 that the issue is still
under discussion with the French administration. But a radiation
protection regulator and an airport medical director said
the discovery that a leaking iridium-192 source from Studsvik
AB went through Roissy Charles de Gaulle airport Dec. 28 on
its way from Sweden to Memphis, Tenn. appeared to have
convinced the company that radiation detectors should be
installed, at least on an experimental basis.
Authorities in Sweden and the U.S. are also probing the
incident, which led to exposure of at least one person-but
only to a calculated 3.4 milliSievert (0.34 rem)-during the
package's final, 10-minute journey from the New Orleans
airport to Source Production & Equipment Co. (SPEC). That
firm ordered the iridium pellets to fabricate an industrial radiography
device (NW, 10 Jan., 1; Inside NRC, 15 Jan., 7).
Jean-Luc Pasquier, scientific director of the Office for
Protection against Ionizing Radiation (OPRI), said dose scenarios
being fine-tuned following an inspection by three
French agencies at FedEx's Roissy hub Jan. 8 indicated that
baggage handlers could hypothetically have received a few to
a few tens of microSv during manipulation of the package,
which contained iridium pellets totaling 366 terabecquerels,
or some 10,000 curies. He also said French authorities now
suspect, based on the inspection, that the frequency at Roissy
airport of so-called Type B packages-those designed to
contain the largest amount of radiation-is higher than had
been thought, raising the question of cargo workers' total
The development of air cargo traffic like FedEx's,
which transits several intermediate points, could also call into
question France's regulations on transport of dangerous materials,
which date from 1980 when most sources were sent
directly from producer to user, Pasquier said Jan. 15. He said
the apparent increased frequency of large source shipments
could require FedEx and other companies to employ baggage
handlers licensed as radiation zone workers.
He said OPRI is still working on scenarios to calculate
potential doses during handling of Type B packages at FedEx,
based on observations at Roissy. But Pasquier expects the
agency's conclusions from the inspection, likely to be issued
late this week or early next, to include recommendations to
install ambient radiation monitors in the FedEx facilities and
to equip one or two typical FedEx employees with personal
dosimeters on a trial basis for three to six months.
OPRI inspected the FedEx facility Jan. 10 along with
nuclear safety authority DSIN and the French Civil Aviation
Authority (DGAC). All the organizations said there appeared
to have been no exposure over the statutory limit of 1 mSv,
and confirmed FedEx statements that the pilots of the flight
from Paris to Memphis, Tenn., had registered no significant
dose (less than 1 millirem) on their personal dosimeters. The
package, which was discovered to be leaking radiation upon
its arrival at New Orleans airport, was in the hold about 20
meters from the pilots on that flight, said DSIN acting fuel
cycle-transport director Jacques Aguilar.
Both Pasquier and Aguilar described the FedEx Paris
operations as "very professional" and said they were satisfied
with the company's handling of radioactive cargo. But Pasquier
said the increasingly international trade in radioactive
sources and the nature of the sources themselves justified a
review to see if regulations adequately protect those who
come into contact with the packages. He observed that the
iridium-192 source was nearly as potent as sources (typically
cobalt-60) used in land-based industrial irradiators which are
classified in France as major nuclear installations and regulated
Pasquier said that based on FedEx's statement that the
iridium package spent a maximum of five hours at Roissy,
including about three hours in a hangar, OPRI had calculated
that if Type B packages transit at the airport every two weeks
on average, "you're no longer in the domain of 'public' dose
limits," which have recently been lowered from 5 mSv to 1
mSv a year.
Pasquier said that French experts have no proof that Fed-
Ex employees are getting too high doses, but only "elements
that allow us to suspect it." He said that if OPRI can prove
that large sources are transiting at Roissy more frequently
than once every few months, which has been the assumption
up to now, the DGAC could oblige FedEx to license its workers
as radiation workers.
Care Was Taken
Philippe Bargain, chief medical officer at Aeroports de
Paris, the company that manages the Roissy site, said indications
are that "only one FedEx employee could have been
irradiated" by the iridium package at Roissy, since it was
handled only by one person, but the assumption was he received
no significant dose. Bargain said the FedEx employees'
health and safety committee had raised questions about
the transport, but concluded that "if they (the personnel)
didn't go on strike, it proves they were satisfied" that the
situation wasn't serious. Bargain, too, paid tribute to FedEx's
scrupulous respect for regulations.
Cliff Morley, a FedEx spokesman in London, said employees
who handle radioactive packages at the company's
facilities "do have the necessary protection, they do have the
materials" to measure radiation levels. Pasquier later said that
was true inside aircraft, but not on the ground. Morley said
that Type B packages represent "less than 0.5% of the packages
delivered daily" by FedEx's system.
Regulations governing Type B packages stipulate a maximum
dose rate at a package's surface of 2 mSv/hour. That
means, Pasquier observed, that a baggage handler who spent
an hour near one of the packages could exceed the public
dose limit. He also suggested that regulations on Type B
packages might need revision if it is found that the packages
can't guarantee leaktightness in an aircraft crash.
Type B packages, also used to transport spent fuel, are
currently the most stringent type of radioactive materials
transport packaging, but new international regulations now
coming into force raise the possibility of transporting certain
particularly risky materials, such as mixed-oxide fuel, in
packages meeting even stricter criteria, known as Type C.
Regulators in Europe continued to chafe at the lack of
information on the iridium-192 package from U.S. authorities
since the package was isolated in a hot cell at SPEC last week.
Aguilar and others said it's crucial to open the package to find
out what happened to allow escape of the radiation from what
was supposed to be a leaktight package.
SPEC and Studsvik were understood early this week to be
negotiating the possible transfer of the package from SPEC's
facilities outside New Orleans to Studsvik's site at Erwin,
Tenn. Though SPEC would have had to open the Studsvik
package to extract the tubes containing the iridium pellets for
incorporation into a radiography device, SPEC claims it
would have to construct a special enclosure to open the damaged
package. Sources said they suspected commercial and
liability issues were also at play in the discussions between
SPEC and Studsvik.
Meanwhile, the FedEx Pilots Association (FPA) is questioning
whether there needs to be a tightening of requirements
for transport of hazardous goods. The Memphis-headquartered
FPA represents more than 4,000 pilots based in Memphis,
in Anchorage, Alaska, and in Subic Bay, the Philippines.
Spokesman Kevin Scheiterlein said he's sure FedEx complied
with requirements, but said a shipment as radioactive as
iridium-192 should perhaps be equipped with a monitor to
alarm if the package began leaking. Also, reporting requirements
should be strengthened, he said. "We didn't find out
about this for several days," he said.
FPA is awaiting the outcome of various regulatory investigations
before proposing anything, he said.
More FedEx pilots may have been exposed than the six
crew members during the flights from Sweden to France and
on to the U.S., he said. The package was placed near a crew
lounge area in New Orleans, he said. Scheiterlein said he's
confident that the investigation will show no one was exposed
to harmful levels of radioactivity. However, he noted, it's not
known when the package began emitting radioactivity. Sources
have told him the package didn't appear to be damaged.
The event apparently has not generated much concern
among pilots. Scheiterlein said the FPA has sent out two email
messages to members and hasn't received many responses.
Most FedEx pilots are aware the company carries dangerous
goods, he said, but, "Most pilots I talked to were not
aware we were carrying stuff this hot."
Scheiterlein said he's unaware of a similar instance involving
a leaking radioactive shipment. However, he said, in
the past, FedEx misplaced an iridium shipment from Massachusetts
bound for elsewhere in the U.S. The shipment, which
was not leaking, wound up in England, he said.
NRC Suspects Packing Problem
A U.S. NRC official suggested the leaking in the package
shipped to SPEC could have been caused by improper packing.
"My feeling is it was accidental," Carl Paperiello, NRC
deputy executive director for materials, research and state
programs, said Jan. 15. "My guess is a spacer was left out and
a source shifted inside."
Paperiello speculated the other possible scenario causing
the leakage was an overpacked container, which he does not
believe to be the case because the radioactivity appeared to be
"asymmetrical." He said he believes a source moved toward
the edge of the shield.
France's IPSN said the iridium-192 pellets were in three
tubes, which were in turn placed in 10-mm-thick tungsten
capsules with screw-on lids. The capsules were placed in
cylinders made of depleted uranium, 63 mm thick-the biological
shielding. All of the above was placed in a steel drum
meeting Type B transport package standards.
IPSN says the dose rates measured at New Orleans
correspond to a decrease in U shielding thickness of about 50
mm, so the search for the cause is focusing on the possibility
that the plug on the uranium cylinder shifted after an error in
handling, or that the someone had forgotten to put on an additional
piece that holds the plug in place, or forgotten screws
that also hold it in place.
Paperiello called the event "incredibly rare." The last time
there was a similar incident was in March 1990, when a radiographic
source was erroneously packed in a shipment of 14
source changers from NDI Corp. in Seoul, South Korea to
Amersham Corp., a manufacturer of iridium-192 and cobalt-
60 based in Burlington, Mass. The source changers, which are
shielded devices for transporting sealed source assemblies,
were supposed to have been empty. But a wooden crate containing
the source changers was damaged in transit and a
sealed source was discovered by an Amersham employee.
NRC investigated to determine the potential for exposure by
several individuals who came in contact with the source
In the latest incident, NRC has no jurisdiction over the
Swedish licensee, Paperiello said. However, had it been a
U.S. licensee, he added, NRC likely would have issued a
violation and levied a fine.
-Ann MacLachlan, Paris; Tom
Harrison and Jenny Weil, Washington
©2002 The McGraw-Hill Companies, Inc. Reproduction forbidden without permission.