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KCP Promethium Contamination: A Comedy of Errors

In 1970, engineers at the Allied Signal KCP decided to design and build their own test apparatus for measuring aluminum deposited on Mylar substrates. They decided they wanted a Beta Radiation source so that they might measure the electron backscatter. Due to their position as a classified National Nuclear Security Agency contractor, working under the auspices of the Department of Energy, all they needed to do to get a new and unique radiation source, was make a call to Oak Ridge National Laboratory. And so, our comedy of errors begins.

Uranium-238, with a 4.5-billion-year half-life, has only 0.00015 curies of activity per pound, while cobalt-60, with a 5.3-year half-life, has nearly 513,000 curies of activity per pound. This "specific activity," or curies per unit mass, of a radioisotope depends on the unique radioactive half-life and dictates the time it takes for half the radioactive atoms to decay.1

The Beta Radiation source that Allied Signal was provided by Oak Ridge National Laboratory, was Promethium 147 with a half-life of 2.7 years, so its specific activity for the radioactive source was 2,724,000 Curies per pound! The source was specified to be created as a high level beta radiation in a energy range not available from commercial radioactive sources, and was specified as being 200 mCi (milliCuries), whereas, commercial radiation sources used in nuclear medicine are in the range of 5 to 50 mCi.

There are both very precise and exacting material handling and safety controls required for all commercially available radiation sources. Every doctor office, dentist office, or hospital in the United States has to follow and document these procedures every day. Yet, each commercial radiation source has to be sealed, by definition: surrounded by an impermeable layer, and capable of withstanding having a hammer dropped on it from a height of three feet without breaking. The Promethium sources provided by Oak Ridge National Laboratory were glass, and sealed with a thin layer of adhesive, they did not come close to meeting the definition of sealed radiation source. A much more stringent set of safety and handling protocols are required of experimental, unsealed radiation sources. Oak Ridge National Laboratory noted that the radiation source was NOT sealed in the shipping documents that came standard with every shipment, yet in the nearly twenty years from creation of the electron backscatter test stand until the discovery of the contamination, KCP personnel never properly followed the far looser safety precautions specified for the sealed commercial radiation sources.

The safety and material handling procedures for sealed, commercially available radiation sources require “swipe testing” each source after receipt. KCP actually did do this, however, not understanding the nature of the radiation emitted by Promethium, every test was completely invalidated by not calibrating their instrumentation to properly detect the beta radiation in the energy range emitted by Promethium! In fact, for most of the time, they presumed, in complete error, that their dose badges would detect the radiation. So, by the time 1986 rolled around, they were opening the Promethium sources at their desk, rather than under a vented hood, as specified for sealed, commercial radiation sources. However, the safety and material handling requirements for UNSEALED EXPERIMENTAL radiation sources actually required that they be opened in a sealed “glove box”, that the air be constantly monitored for escaped radiation, and that even the packing materials be disposed of as hazardous radioactive waste!

Let’s go back to discuss the procurement process for a bit. Basically, someone at KCP wanted a beta radiation source more powerful than was commercially available. He specified a Promethium source that emitted roughly 5 or 10 times what was available as a commercial source (see the Activity in the Nuclear Medicine Chart). Oak Ridge National Laboratory managed to come up with a process to create a 200-mCi radiation source like what the KCP engineer had requested, however, it could not be sealed, which was specifically noted to the KCP personnel. KCP had no formalized procurement process for radiation sources; so, internal audits of nuclear sources never included the Promethium sources used by the Non-Destructive Test Lab, further there were no special disposal instructions for spent sources or packaging materials. It wouldn’t have mattered, although the KCP personnel did have test equipment available that could have measured the beta radiation emitted by the ORNL Promethium sources, they didn’t have the training to realize how to do so, or even that the nature of beta radiation sources implied a fundamentally different set of requirements for detection.

Now, in 1974, both the original engineer at KCP that had requested the Promethium sources, and his contact at the Oak Ridge National Laboratory, retired. Yet, Oak Ridge faithfully fulfilled every request from KCP for new Promethium sources, even though the original expertise that had created the process had gone. So, the both the quality and workmanship of the radioactive sources declined and yet, with safety and handling procedures incompletely followed and improperly applied at KCP, it is clear where blame for the numerous cases of contamination lies. Several incidents of shattered glass Promethium sources were noted in the period from 1974 to 1986, but failing to follow minimal safety and regulatory reporting requirements; none of these incidents were properly decontaminated or reported to DOE. Worse yet, the Oak Ridge process for creating the radioactive sources used a soluble Promethium nitrate salt, which meant that rather than a chemically inert oxide, any released Promethium would readily dissolve in water.

During this same period, Allied Signal decided that having Health Physics personnel on staff was not cost effective, so they switched to contracting for Health Physics services. Why is this significant? Because, despite having an operating budget in the neighborhood of two billion dollars, Allied Signal management felt comfortable cutting less than 50K$ from their budget by reducing their protection of the public and their own employees from the danger of radiation. All because they hadn’t bothered to look at simple facts, that many different kinds of radioactive sources that were in use inside KCP! All this time they had an out-of-control, undocumented process using an unsealed, highly radioactive source material, and their normal methods of detecting contamination (designed to detect gamma radiation) didn’t work. Finally, in 1986, someone realized that to detect the beta radiation emitted by Promethium required both a different instrument and different settings on that instrument than were normally used. Still, it was over a year before they put that knowledge together and walked into the Non-Destructive Test lab.

Surprise! They found high levels of contamination on the electron backscatter test machine, but the bigger surprise was that they found radioactive contamination in several other areas of that room and the offices nearby. They didn’t know what to do, so they called their “contracted Health Physics specialist”. He was not available, so they closed the offices and told the physical plant to shut down the air supply to the contaminated areas (not knowing that there was no way to do so from there). Okay, what SHOULD have happened was that they should have immediately called the National Emergency Response Hotline, which would have kicked off a national level response and completely sealed off the affected area. However, on the following Monday, workers were allowed into the contaminated areas, and they finally got in contact with their Health Physics contractor.

The Health Physics contractor contacted management and the KCP hazardous materials handling team, only to find that they had no emergency procedures or training for handling a radiological hazard. He then contacted the National Emergency Response Hotline, and a team of investigators from Sandia National Laboratory Albuquerque and Los Alamos National Laboratory arrived in less than 24 hours. For the most part, the team of investigators from the two National Laboratories did a fine job under near impossible conditions. They found contamination within the KCP in three test labs and two office areas. They even checked the personnel and found several of them were contaminated, so they did a follow up at their residences. At least one of the residences was heavily contaminated, and pieces of the rug, all of the bedding, pair of slippers, and several pairs of trousers were taken back to KCP to be disposed of as contaminated radioactive waste. They even did a follow up visit and found contamination in the apartment building’s laundry room. Further, another one of the employee’s residences was initially found to be contaminated, but they later dismissed it as being from Radon, despite readings more than triple what can be attributed to Radon.

Then they tested several of the employees that worked in the area to see if they had absorbed any of the Promethium into their bodies, and initial results were positive. So, they started a second round of testing of even more employees, and in yet another surprise, the initial results were found to be a “false positive” and no further testing was ever done. No explanation of how such a critical test could have been improperly reported, no explanation of the testing method, and extremely suspicious. Why is the result of no biological (bodily) contamination so suspicious? Two reasons; first, we already have a documented case of known contamination exposing at least one worker to contamination in high enough concentrations to have it carried to his or her home and contaminate articles there. Second, and this is crucial and probably forgotten at the time, the Promethium was in a water-soluble form, a salt readily absorbed by the body!

The investigation team from Sandia National Laboratory Albuquerque and Los Alamos National Laboratories did a find many areas of contamination. However, they never did follow the minimum requirement for handling unsealed radiation sources, and never sampled the airborne component, despite acknowledging that the contamination was in fine dust form. The National Laboratory’s team was not equipped to do the decontamination cleanup, and further, they found that Allied Signal personnel at KCP were not equipped to do a proper decontamination. KCP management contracted Rocketdyne Division of Rockwell International Corp. to do the cleanup. During the cleanup, Rocketdyne personnel broke off a 1” water line, and it flooded the contaminated area. After testing the water and finding no measurable radiation, they released it into the drains. Big mistake, again the fact that the Promethium was in a water-soluble salt form was conveniently forgotten. The beta radiation from Promethium cannot penetrate water, and even a pound of promethium dissolved into the hundreds of gallons from the spill would not have been detectable! Yet, by pouring that radioactive waste from the most contaminated area down the drain, they could have released more radiation then was released by the Three Mile Island disaster!

No one knows how much radiation was released during the contamination and cleanup, and since Promethium has a half-life of only 2.7 years, for every kilogram of Promethium released in 1988, less than 12 grams would be left today, as the rest transmuted through radioactive decay. The water-soluble salts released into the drains would eventually decanted out to a solid, fine dust, easily carried by air currents. That is important because the main danger from Beta Radiation is if the source is inhaled. There is no easy conversion from Curies of activity, or counts on a radiation detector to dosages, but the EPA has established standards for airborne radiation exposure, and it is extremely low. (Figure 2)

Figure 1

Radiation Exposure from Various Sources 1

Source

Exposure

External Background Radiation

60 mrem/yr, US Average

Natural K-40 and Other Radioactivity in Body

40 mrem/yr

Air Travel Round Trip (NY-LA)

5 mrem

Chest X-Ray Effective Dose

10 mrem per film

Radon in the Home

200 mrem/yr (variable)

Man-Made (medical x rays, etc.)

60 mrem/yr (average)

Both public and occupational regulatory dose limits are set by federal agencies (i.e., Environmental Protection Agency, Nuclear Regulatory Commission, and Department of Energy) and state agencies (e.g., agreement states) to limit cancer risk. Other radiation dose limits are applied to limit other potential biological effects with workers' skin and lens of the eye. In the following table, anyone who achieves a lifetime dosage of 5,000 rems is considered occupationally exposed and retired medically with a much higher chance of getting cancer, and is just short of the dosage to cause “radiation sickness”. Secondarily, the EPA dose limits for airborne contaminants is at issue, as the contaminated area was not provided with a separate air filtration or supply system, nor was the air monitored for airborne contaminants throughout the usage of the Pr 147 “experimental source, which are still in use to this day.

Figure 2

Annual Radiation Dose Limits

Agency

Radiation Worker - 5,000 mrem

(NRC, "occupationally" exposed)

General Public - 100 mrem

(NRC, member of the public)

General Public - 25 mrem

(NRC, D&D all pathways)

General Public - 10 mrem

(EPA, air pathway)

General Public – 4 mrem

(EPA, drinking-water pathway)

By comparison, the following table shows the dosages from various radiation treatments: 2

Typical Doses from Nuclear Medicine Exams

Nuclear Medical Scan

Activity, mCi (MBq)

Radiopharmaceutical

Effective Dose, mrem (mSv)

Brain2

20 (740)

99mTc DTPA

650 (6.5)

Brain3

50 (1,850)

15O water

170 (1.7)

Brain4

20 (740)

99mTc HMPAO

690 (6.9)

Hepatobiliary2

5 (185)

99mTc SCO

370 (3.7)

Bone2

20 (740)

99mTc MDP

440 (4.4)

Lung Perfusion/Ventilation2

5 & 10
(185 & 370)

99mTc MAA & 133Xe

150 (1.5)

Kidney2

20 (740)

99mTc DTPA

310 (3.1)

Kidney3

20 (740)

99mTc MAG3

520 (5.2)

Tumor2

3 (110)

67Ga

1,220 (12.2)

Heart3

30 (1,100)

99mTc sestimibi

890 (8.9)

30 (1,100)

99mTc pertechnetate

1,440 (14.4)

Heart4

2 (74)

201Tl chloride

1,700 (17)

30 (1,100)

99mTc tetrofosmi

845 (8.45)

Various3

10 (370)

18F FDG

700 (7.0)

From the University Of Maryland Medical Center, the following excerpt is provided. 3

Radiation sickness results when humans (or other animals) are exposed to very large doses of ionizing radiation. Radiation exposure can occur as a single large exposure (acute), or a series of small exposures spread over time (chronic).

Radiation sickness is generally associated with acute exposure and has a characteristic set of symptoms that appear in an orderly fashion. Chronic exposure is usually associated with delayed medical problems such as cancer and premature aging, which may happen over a long period of time.

The risk of cancer depends on the dose and begins to build up even with very low doses. There is no "minimum threshhold."

Exposure from x-rays or gamma rays is measured in units of roentgens. For example:

  • Total body exposure of 100 roentgens (or 1 Gy) causes radiation sickness.
  • Total body exposure of 400 roentgens (or 4 Gy) causes radiation sickness and death in half the individuals. Without medical treatment, nearly everyone who receives more than this amount of radiation will die within 30 days.
  • 100,000 rads causes almost immediate unconsciousness and death within an hour

  

 References:

  1. Health Physics Society article Radiation Basics http://www.hps.org/publicinformation/ate/faqs/radiation.html
  2. Health Physics Society article Medical Radiation Doses http://www.hps.org/hpspublications/articles/dosesfrommedicalradiation.html
  3. University of Maryland Medical Center > Medical Reference > Encyclopedia http://www.umm.edu/ency/article/000026.htm
  4. Report of Investigation of Pm 147 Contamination

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