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Important Notice: The Hanford Health Information Network (HHIN) closed in May, 2000. HHIN Web pages are provided as archived information only, and are not currently maintained. Information contained on the HHIN Web pages may be out-of-date.

Current information is available through the Hanford Community Health Project, which is updated by the Agency for Toxic Substances and Disease Registry of the U.S. Centers for Disease Control and Prevention.

The Release of Radioactive Materials from Hanford: 1944-1972

This report presents information on the release of radioactive materials into the environment from Hanford's historical operations (1944-1972). While smaller releases have continued since 1972, the Congressional mandate for the Hanford Health Information Network (HHIN) limits the Network to providing information about the releases of radioactive materials from 1944 to 1972. This publication provides a brief historical sketch and describes Hanford's releases into the air, water and soil. The last section discusses the uncertainties in the estimates of the amount of radioactive material released and whether the government continues to withhold important information.

Historical Background

In 1943, the U.S. government chose a location in southeastern Washington state for the Hanford Nuclear Reservation, now known as the Hanford Site. The federal government condemned privately-held property and moved the residents so it could build plants to make plutonium. Because of the wartime secrecy, few people knew why Hanford was built. It was not until August 6, 1945, when the United States dropped an atomic bomb on Hiroshima, Japan, that area residents and most Hanford workers learned that Hanford made plutonium.1 Hanford had begun making plutonium in September 1944, when the B reactor began operating. Hanford plutonium was used in the first atomic explosion in July 1945 at Alamogordo, New Mexico, and in the bomb that was dropped on Nagasaki, Japan (August 9, 1945).

For more than 40 years, Hanford released radioactive materials into the environment. Although Hanford's mission of making plutonium became public knowledge in 1945, most of the public and some Hanford workers did not know about these releases until 1986. In February 1986, the U.S. Department of Energy, in response to public pressure and a request under the Freedom of Information Act, released 19,000 pages of documents, some dating back to World War II. These documents revealed that releases of radioactive materials from Hanford had contaminated the air, the Columbia River, and the soil and groundwater.

Citizen activists played an important role in making these and other Hanford documents open to the public. In the early 1980s, many citizen groups began to scrutinize the operation of Hanford. One group, the Hanford Education Action League (HEAL), raised numerous questions about the past and present safety of Hanford. HEAL, along with other groups, such as Physicians for Social Responsibility (PSR) and Hanford downwinders, pressed the U.S. Department of Energy for the release of additional historical documents. Journalists, as well as state and Native American governments, also played important roles in the release of Hanford records. 

The information in these documents eventually led to the Hanford Environmental Dose Reconstruction Project (HEDR) which began in late 1987. HEDR made estimates of the radiation doses the public may have received from Hanford. The project was beset with public controversy from the start. Citizens leveled charges of conflicts of interest at the U.S. Department of Energy (which owned Hanford and was funding the study), as well as at Battelle Pacific Northwest Laboratory, a longtime Hanford contractor, which was conducting the scientific work. To try to alleviate some of the public's concern, an independent technical steering panel was created to direct the project.2

In 1992, HEDR funding was transferred from the Department of Energy to the Centers for Disease Control and Prevention (CDC). In 1994, Battelle's HEDR contract expired and CDC hired other contractors to complete the study. The HEDR study is scheduled to complete its work in 1998. 

A key step in reconstructing doses is estimating how much radioactive material was released to the environment. Scientists refer to the amount released as the source term. By reviewing Hanford's historical documents, HEDR obtained information for making release estimates. The following sections describe these source term estimates for the air, the Columbia River, and the soil and groundwater.

Air Releases

Most of Hanford's air releases came from the routine operation of the chemical plants used to separate plutonium and uranium from used reactor fuel. Some of the air releases came from the nuclear reactors along the Columbia River.3 The major radioactive releases occurred between 1944 and 1957. The largest ones were during 1945, when there were no filters on the stacks of the separations plants. In only five months, Hanford discharged more than half of the entire amount of iodine-131 released during the entire 1944-1972 period.4 Radioactive materials in the form of gases and particles went up the stacks.

Filters were installed in 1948 that greatly reduced, but did not eliminate, the releases to the air. More advanced filters were installed in December 1950 that further reduced the releases. However, the filters would occasionally fail and this would result in some above-normal releases. The largest of these filter failures occurred in the spring and summer of 1951.5

In all, Hanford released over 200 radionuclides.6 Reconstructing past doses from Hanford's releases was a huge undertaking. (By the time HEDR is complete in 1998, it will have cost about $30 million.) To help set priorities, HEDR scientists used scoping studies.
Green Run
Most of Hanford's radioactive releases happened as part of routine operations. But Hanford's largest single release of iodine-131 was the result of a secret military experiment. "Green Run" refers to a secret U.S. Air Force Experiment at Hanford that released somewhere between 7,000 and 12,000 curies of iodine-131 to the air on December 2-3, 1949. The experiment was called the Green Run because it involved a processing "run" of uranium fuel that had been cooled for only a short time (16 days), and was, therefore, "green." The normal practice in 1949 was to cool the fuel 90 to 100 days before processing. The longer cooling time allows for radiation, especially iodine-131, to decay to lower levels.

The reported purpose of the Green Run was to test monitoring equipment the Air Force was developing for its intelligence activities concerning the Soviet Union's nuclear weapons program. The Green Run remained a top government secret until the 1980s when reports were made public in response to Freedom of Information Act requests. The requests were filed by the Hanford Education Action League and the Spokesman-Review newspaper, both based in Spokane. The U.S. Air Force continues to withhold significant information about the Green Run including the names of the official(s) who ordered the experiment and the intelligence unit that participated in the monitoring.

The scoping studies were rough calculations of what Hanford released and which radionuclides contributed the most to the public's dose. According to HEDR, most of the radionuclides had little or no effect on public health because: they were released in small amounts; they became non-radioactive quickly; or there was little public exposure to them. For example, krypton-85 and xenon-133 are "noble gases" which do not readily react chemically with other materials. This greatly lessens the potential for these radionuclides to be absorbed by living organisms.

Some radionuclides, while not posing a significant risk to the public, might have been a special hazard to workers, security guards and soldiers at Hanford. This situation is part of continuing HEDR work and a report is expected in 1998.

HEDR estimated the amounts of iodine-131 and other radioactive materials Hanford released into the air between 1944 and 1972. Table I (below) presents the radionuclides for which specific estimates were made. The release estimates are in curies, a unit of measurement of radioactivity. As an example, HEDR estimated that Hanford released about 740,000 curies of iodine-131 from 1944 to 1972. For comparison purposes, the Three Mile Island nuclear power plant accident in 1979 released an estimated 15 to 24 curies of iodine-131, and the Chernobyl accident released an estimated 35 million to 49 million curies of iodine-131 in 1986. Table I also presents the half-life (a measurement of the rate of radioactive decay) of each radionuclide.

HEDR Estimates of Radiation Released
into the Air by Hanford, 1944-1972
Radionuclide Amount Released (curies)7 Half-Life
Iodine-131 740,000 8 days
Tritium (H-3) 200,000 12 years
Cobalt-60 1 5 years
Krypton-85 19,000,000 11 years
Strontium-89 700 50 days
Strontium-90 64 29 years
Zirconium-95 1,200 64 days
1,200 39 days
Ruthenium-106 390 370 days
Iodine-129 46 16 million years
Tellurium-132 4,000 78 hours
Xenon-133 420,000 5 days
Cesium-137 42 30 years
Cerium-144 3,800 284 days
Plutonium-239 1.8 24,000 years
It is important to understand that the amount released is not the same as the dose people received. For example, even though krypton-85 was released in large amounts and has a fairly long half-life, it did not contribute much to dose because it did not deposit on the ground nor contaminate food. HEDR estimated that iodine-131 was the major contributor to dose from the releases into the air. It was released in relatively large amounts. HEDR also estimated doses from five other radionuclides: ruthenium-103, ruthenium-106, strontium-90, plutonium-239 and cerium-144. Members of the public were exposed to other radionuclides. However, HEDR estimated that their contribution to the public's dose was so small that HEDR did not consider it worth the effort required to estimate doses. Due to iodine-131's large contribution to dose, it was the main focus of HEDR's work. The ways people were exposed to iodine-131 included drinking contaminated milk, eating contaminated fruits and vegetables, and breathing contaminated air. Once in the body, iodine-131 concentrates in the thyroid gland.8 The most likely health effect of this exposure is thyroid disease. This is the subject of the Hanford Thyroid Disease Study (HTDS) which is being conducted by the Fred Hutchinson Cancer Research Center in Seattle, Washington, for the CDC. The HTDS is investigating whether thyroid disease is increased among people exposed to the iodine-131 released from Hanford. 


Some of the radiation released to the air was attached to particles. The earlier HEDR work did not include particle releases (therefore, the release estimates in Table I will need to be updated). HEDR is studying the releases of ruthenium and plutonium particles. 

Most of the ruthenium particles were released between 1952 and 1954. Some were found as far away as Spokane. Particles containing plutonium and other radionuclides were released in large numbers from at least 1945 until 1951. These particles were also found in Spokane as well as on Mount Rainier and along the Idaho-Montana border. For more detail, please refer to HHIN's Potential Health Problems from Exposure to Selected Radionuclides.


In addition to producing plutonium for use in nuclear weapons, Hanford also produced tritium, which is another nuclear weapons material. HEDR reported that Hanford's tritium production resulted in an estimated 200,000 curies being released to the air from the 108-B facility. These releases occurred from 1949 through 1954 with more than half being released in 1954.9

Tritium was also released from the production and processing of plutonium. Air releases from the reactors contained tritium; however, HEDR did not report a total amount released.10 Hanford's plutonium separations plants released tritium to the air as well, but HEDR did not report any estimate for the total amount.

Columbia River Contamination

The first eight nuclear reactors at Hanford used large amounts of Columbia River water to directly cool the reactor cores. The water went through the reactors once and then back into the Columbia River, carrying radioactive materials with it. In addition, radioactive materials that built up inside the reactors were regularly flushed loose during cooling system purges and entered the Columbia River.

These eight reactors were at their highest power between 1955 and 1965. Contamination of the Columbia River was highest during this time. The last of these eight reactors shut down in January 1971.

HEDR estimated that five radioactive substances accounted for most of the dose people received from the Columbia River. They are zinc-65, arsenic-76, phosphorus-32, sodium-24 and neptunium-239. Table II lists these and other radionuclides that were released to the Columbia River. Based upon scoping studies, HEDR decided not to include in the dose estimates the other radionuclides listed here because, in HEDR's opinion, these did not contribute significantly to the dose to the public.

HEDR Estimates of Radiation Released
into the Columbia River by Hanford, 1944-1971
Radionuclide Amount Released (curies)11 half-life
Sodium-24 13,000,000 15 hours
Phosphorus-32 230,000 14 days
Scandium-46 120,000 84 days
Chromium-51 7,200,000 28 days
Manganese-56 80,000,000
Zinc-65 490,000 245 days
Gallium-72 3,700,000 14 hours
Arsenic-76 2,500,00 26 hours
Yttrium-90 450,000 64 hours
Iodine-131 48,000 8 days
Neptunium-239 6,300,000 2.4 days

People received exposure from the river in several ways: eating contaminated fish and shellfish, drinking contaminated water, swimming in or boating on the Columbia River downstream from Hanford, or spending time along the river shoreline. According to HEDR, eating fish and shellfish was the main way people were exposed to radiation from Hanford's reactors. For further information, please see HHIN's Radionuclides in the Columbia River: Possible Health Problems in Humans and Effects on Fish.

Soil and Groundwater Contamination12

According to the U.S. Department of Energy, about 60 million gallons of highly radioactive waste from the chemical separations plants are stored in 177 underground tanks at Hanford. The tanks contain about 200 million curies of radioactivity. Over the years, more than 1 million gallons, containing over 100,000 curies of radioactivity, have leaked into the soil. At present, it is uncertain whether any of this waste has reached the groundwater.

In contrast to the tank wastes, it is known that much of the groundwater underneath Hanford has been contaminated by radioactive process wastes. The separations plants required large amounts of water to process plutonium and this water became contaminated inside the plants. Hanford has estimated that over 440 billion gallons of these radioactive wastes were dumped into the ground. Some radioactive materials traveled through the soil and entered the groundwater. During Hanford's early years, other radioactive wastes penetrated the groundwater through "injection wells," or shafts drilled deep into the ground.

Tritium is the most commonly found radionuclide in the groundwater at Hanford. Ruthenium-106, technetium-99 and iodine-129 are three of the other radioactive materials commonly found in Hanford's groundwater. Some radioactive substances still remain in the soil and may enter the groundwater in the future.

HEDR concluded that there was little human contact with the contaminated groundwater in the past. In the future, Hanford's groundwater contamination could pose a danger to the public.

Hanford also buried solid wastes in the soil. This waste contains nearly 5 million curies of radioactivity.

downwinder perspective
Many callers to the Hanford Health Information Lines have questions and concerns about Hanford's releases of radioactive materials. Some downwinders have health problems and believe that these problems are, or might be, related to Hanford. The following personal perspective is offered to help readers understand these experiences and concerns. This perspective is an excerpt from a downwinder's contribution to the Hanford Health Information Archives.

When [my youngest son] was seven--and again when he was eight years old--I had two surgeries for thyroid cancers. I didn't tell people because it would be hard on our children....

In 1985 my husband died quite suddenly. Early in 1986 word got out that radioactive iodine-131 and other pollutants had been released in large amounts by the government just to see what would happen to us downwinders from the nuclear plant at Hanford, Washington.

With the injuries from my thyroid cancers and the worry over my husband's bladder and bone cancers, I was very angry and felt betrayed by my government. They used us as guinea pigs but we weren't even that good because the government never followed up to see what did happen to us downwinders.

I write poems, but they are all too mild for my anger at my government.


It's as safe as mother's milk, they'll say
When wanting to assure you that it's all O.K. If mom, a downwinder, eats Columbia River's fish,
Or consumes white snow - garden salads on the spot
Then mother's milk can become a deadly lot.

So I fed poison to my nursing son
With radioactive iodine-131.
Just because we lived in the wrong place
I maimed my babe for that nuclear race.

Written by a woman who has lived all of her life in Eastern Washington and remembers consuming local milk and produce. Her husband loved to fish the Columbia River downstream from Hanford. Name withheld by request.

Reviews of the HEDR Project

While HEDR has been the only study to estimate radioactive releases from Hanford, there have been several scientific reviews of HEDR's work. A committee of the National Research Council (NRC) reviewed two summary HEDR reports and concluded that "while the work that went into these reports is impressive, the reports are not adequate in their present form in that some serious questions remain."13 However, the committee did not review all of the background reports that contained key details of how the project estimated the amounts released and the resulting exposures. HEDR's Technical Steering Panel responded with a letter to CDC which said in part: "While we appreciate the NRC review of the Project's work, we are concerned that the review was incomplete and the NRC conclusions are therefore misleading."14

As part of the consolidated lawsuits brought by about 3,000 downwinders against former Hanford contractors, each side has hired scientific experts to prepare reports that assess HEDR's work. The judge hearing the case has also retained a scientific expert. Most of the reports prepared by the experts have not been released publicly. News articles have described one as saying that Hanford released hundreds of times more plutonium than HEDR estimated.15 CDC has told the states of Idaho, Oregon and Washington that "while CDC does not routinely provide formal review and comment on documents related to ongoing litigation issues, CDC staff do review and consider documents such as these for any new technical information they might contain. None of these reviews suggests that there are major unresolved methodological issues associated with the HEDR report produced to date."16

Concerning HEDR's work on the radionuclides released to the Columbia River, another scientist has completed a critique recommending additional 17 This report should be available to the public in 1997.

Sources of Uncertainty

Reconstructing how much radiation Hanford released into the environment is difficult for three main reasons: (1) there are gaps in the historical information; (2) environmental monitoring techniques were being pioneered during Hanford's early years; and (3) so much time has elapsed since the first releases. Because of incomplete knowledge or missing information, there is an amount of uncertainty associated with the HEDR release estimates. This section explains how HEDR reported uncertainty in the release estimates, what was not included in the estimates, and whether the government continues to withhold historical information.

Range of Release Estimates

Scientists generally report their estimates as a range of numbers, from the lowest that is reasonable to the highest. This range of numbers represents how confident the scientists are that their estimates reflect the amounts of radioactive materials that were actually released. If the range from low to high numbers is relatively small, then the scientists are more certain that their estimates accurately reflect what happened. If the range is large, then the scientists are not as certain in their estimates. The HEDR range of uncertainty is large.

Table III presents the range of release estimates for the six radionuclides released to the air that HEDR used in its dose estimates. The numbers shown here as "average"are also the ones that were used in Table I.

Range of Uncertainty:
HEDR Estimates of Air Releases from Hanford,
1944-1972 (in
Radionuclide Low Average High
Iodine-131 630,000 740,000 980,000
Ruthenium-103 330 1,200 4,100
Ruthenium-106 110 390 1,400
Strontium-90 23 64 180
Cerium-144 1,400 3,800 11,000
Plutonium-239 0.1 1.8 31.0

The other radionuclides that were released to the air were considered only during the initial scoping studies. The scoping studies do not include enough information to be able to estimate the uncertainty range for release estimates of these other radionuclides.

For the radionuclides discharged to the Columbia River, HEDR did not report the release estimates in such a way that the uncertainty of the estimates can be easily summarized. Those wanting to review the uncertainty in the estimates of river releases can find some of this information in Appendix B, "Monthly Releases from Eight Single-Pass Hanford Production Reactors," in "Radionuclide Releases to the Columbia River from Hanford Operations, 1944-1971," PNWD-2223, dated May 1994.

Are the Estimates Complete?

The HEDR estimates do not include all of the radioactive material released to the environment as the result of Hanford operations. The dose reconstruction study did not consider all of the possible sources of release because the study's scientists focused their efforts on the sources that, in their opinion, likely contributed the most to the public's exposure. Additionally, HEDR included only a few of the accidental releases because the study's scientists assumed that the accidental releases did not contribute much to the public's total dose (due to these releases being so much smaller than the huge routine releases).

A question yet to be examined is how the accidental and other releases might have affected Hanford workers and military personnel stationed at Hanford. Because workers and soldiers were closer to the sources of the radioactive releases and were in unique situations, they had different exposures than the public. For example, soldiers at Hanford slept in tents only a few miles from the plutonium plants. This important situation is being considered as part of the remaining HEDR work. This work is expected to be complete in 1998.

Is the Government Still Withholding Information?

Many downwinders have asked if the government might still be withholding something about Hanford's environmental releases. Several callers to HHIN over the years have recounted personal experiences (some from former Hanford workers) that are not reported in the historical documents and were not included in HEDR's work. This is yet another source of uncertainty and of unanswered (perhaps unanswerable) questions.

If people want to add their own documents, photographs and recollections about their experience of Hanford's releases, they can contribute copies to the Hanford Health Information Archives. The Archives is a joint project of the Hanford Health Information Network and Gonzaga University, which is located in Spokane, Washington. The toll-free phone number is 1-800-799-HHIA (4442).

Even though there may always be questions about whether the government is withholding information about the Hanford releases, the U.S. Department of Energy has made great progress in declassifying historical documents. Over the past three years, it has declassified more pages than it has classified. Under the leadership of then-Secretary of Energy Hazel O'Leary, the department made millions of pages of documents available to the public as part of the Openness Initiative. Of these, about 400,000 pages were declassified by Hanford. Some can be accessed through the Department of Energy.


1 - The atomic bomb that destroyed Hiroshima, Japan, contained enriched uranium from a plant at Oak Ridge, Tennessee.

2 - Ken Niles, "Reconstructing Hanford's Past Releases of Radioactive Materials: The History of the Technical Steering Panel 1988-1995," Technical Steering Panel (TSP) publication, November 1996.

3 - HEDR reported that three radionuclides were the most important: tritium, carbon-14 and argon-41. However, HEDR did not report a total amount released. For details of the work done, see C.M. Heeb, "Radionuclide Releases to the Atmosphere from Hanford Operations, 1944-1972," PNWD-2222 HEDR, May 1994, Section 5.0.

4 - The five months in 1945 were May, August, September, October and December.

5 - PNWD-2222, p. B.3.

6 - For a complete listing of all 237 radionuclides, please see the HHIN publication A Listing of Radionuclides Released from Hanford, September 1996.

7 - Please note that the numbers are all rounded to two significant figures. Sources: W.T. Farris, et al., "Atmospheric Pathway Dosimetry Report, 1944-1992," PNWD-2228 HEDR, October 1994, p. B.4.; B.A. Napier, "Determination of Radionuclides and Pathways Contributing to Cumulative Dose," BN-SA-3673 HEDR, December 1992, p. B.8; M.A. Robkin and B. Shleien, "Estimated Maximum Thyroid Doses from I-129 Releases from the Hanford Site for the Years 1944-1995," Health Physics, Vol. 69 (6), December 1995,
pp. 917-922; C.M. Heeb and S.P. Gydesen, "Sources of Secondary Radionuclide Releases from Hanford Operations," PNWD-2254 HEDR, May 1994, Section 7.

8 - More information about iodine-131 and the thyroid can be found in other HHIN publications: An Overview of Hanford and Radiation Health Effects and Health Bulletin.

9 - C.M. Heeb and S.P. Gydesen, "Sources of Secondary Radionuclide Releases from Hanford Operations," PNWD-2254 HEDR, May 1994, Section 7.

10 - For details of the work done, see C.M. Heeb, "Radionuclide Releases to the Atmosphere from Hanford Operations, 1944-1972," PNWD-2222 HEDR, May 1994, Section 5.0.

11 - Please note that the numbers are all rounded to two significant figures. Sources: C.M. Heeb and D.J. Bates, "Radionuclide Releases to the Columbia River from Hanford Operations, 1944-1971," PNWD-2223 HEDR, May 1994, p. vii.

12 - "Historical Perspective of Radioactively Contaminated Liquid and Solid Wastes Discharged or Buried in the Ground at Hanford," TRAC-0151-VA, April 1991. Commonly referred to as the "Wodrich Report." See also M.D. Freshley and P.D. Thorne, "Ground-Water Contribution to Dose from Past Hanford Operations." PNWD-1974 HEDR, August 1992.

13 - Committee on an Assessment of CDC Radiation Studies, National Research Council, A Review of Two Hanford Environmental Dose Reconstruction Project (HEDR) Dosimetry Reports: Columbia River Pathway and Atmospheric Pathway (National Academy Press, 1995), p. 2.

14 - Letter from Mary Lou Blazek (TSP Chair) to Jim Smith (Radiation Studies Branch, CDC), June 21, 1995.

15 - Karen Dorn Steele, "Plutonium Filters Called Defective," Spokesman-Review (June 30, 1996), and Jim Thomas, "Radiation Science Update" in HHIN's Connections (Fall 1996).

16 - Letter from Michael J. Sage (Radiation Studies Branch, CDC) to Stephen E. West (Idaho Division of Health), November 18, 1996.

17 - Jim Thomas, "Radiation Science Update," Connections (Winter 1997).

Published Spring 1997


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