MODULE 3
After studying this module, the reader will be able to
The United States government chose a location in south central Washington state in 1943 for the Hanford Nuclear Reservation- now known as the Hanford Site. The government moved area residents in order to build plants for making plutonium at Hanford.
Few people knew before 1945 why Hanford was built. Hanford workers and area residents learned that Hanford made plutonium when the United States dropped an atomic bomb on Hiroshima, Japan. Hanford plutonium was used in the bomb that was dropped on Nagasaki, Japan, and in the first atomic bomb tested in New Mexico.
Hanford began making plutonium in September 1944, and released radioactive materials into the air, water, and soil for more than forty years. However, most of the public and some of the Hanford workers did not know about these releases until 1986 when the United States Department of Energy, in response to public pressure, released 19,000 pages of documents to the public. These documents showed that planned and unplanned releases of radioactive materials from Hanford contaminated the air, the Columbia River, and the soil. The information in these documents led to the formation of the Hanford Environmental Dose Reconstruction Project (HEDR). [*] Citizen activists played an important role in the release of those and other Hanford documents to the public.
Many citizen groups opposed bringing nuclear waste to Hanford in the early 1980s. One group, the Hanford Education Action League (HEAL) formed in 1984, 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 proof of Hanford's safety.
One month before the U.S. Department of Energy's release of the Hanford documents, HEAL, the Environmental Policy Institute in Washington, D.C., and several Northwest groups filed a Freedom of Information Act request for Hanford documents. This request resulted in a second release of documents.
HEDR has estimated the radiation doses the public may have received from Hanford from 1944 to 1992. According to HEDR's estimates, about 2 million people were exposed either through the air or the Columbia River.
By analyzing the 19,000 pages and other historical documents and by using computers, HEDR estimated how much radiation Hanford released and how much people were exposed to based on where they lived and what they ate and drank. For most of those exposed, the greatest part of their total dose came from drinking milk and eating food that was contaminated with radioactive materials from Hanford. For certain people, such as Native Americans, the largest contributor to dose was probably eating contaminated fish.
Most of Hanford's air releases came from the chemical process used to separate plutonium and uranium from fuel rods. Some of the air releases came from the nuclear reactors. The major radioactive releases occurred between 1944 and 1957. The largest ones were from December 1944 through 1947 when there were no filters on the stacks of the separations plants. Radioactive materials in the form of gases, vapors, and particles went up the stacks.
Hanford produced hundreds of radioactive substances. Most had no effect on public health because they were released in small amounts, became non-radioactive quickly, or resulted in little public exposure. HEDR estimates that iodine-131 was the major contributor to dose from the releases into the air. The project is also estimating doses from other radioactive material: ruthenium-103, ruthenium-106, strontium-90, plutonium-239, and cerium-144.
HEDR is re-evaluating early estimates of the amount of air releases from Hanford. In October 1992, HEDR announced new estimates that Hanford released 685,000 curies of radioactive iodine-131 between 1944 and 1947. This amount is based on information found in the U.S. Department of Energy documents made public in recent years.
In January 1994, HEDR presented a new estimate for the amount of iodine-131 which Hanford released between 1948 and 1957. The total estimate for these years was 52,060 curies. Also included in the information offered by HEDR were estimates of the amounts of iodine-131 and other radioactive material Hanford released into the air from 1944 to 1972. These figures are shown in Table 1 below.
HEDR is continuing to study the ruthenium and plutonium releases because some of the radiation released to the air was in the form of particles. Module 10 presents the current data and discusses the possible health effects of plutonium, strontium, cerium, and ruthenium. There are documents that describe how particles from inside the stacks of two Hanford plants collected ruthenium and plutonium. Some went beyond the Hanford Site when the particles broke off and were carried out the stacks. Estimates of the amounts of particles released and the doses received are not yet completed. HEDR plans to complete these estimates by the end of 1997 (see Module 10).
Iodine-131 remains the focus of HEDRs work because of the large amount released. The ways in which people were exposed to iodine-131 include eating contaminated fruits and vegetables, breathing contaminated air, and drinking contaminated milk.
Once in the body, iodine-131 concentrates in the thyroid gland. The most likely health effect of this exposure is thyroid disease. This effect is the subject of the Hanford Thyroid Disease Study (HTDS)[+] being conducted by the Fred Hutchinson Cancer Research Center in Seattle, Washington. HTDS is being conducted for the Centers for Disease Control and Prevention.
| Iodine-131 | 739,000 curies |
| Ruthenium-103 | 1,160 curies |
| Ruthenium-106 | 388 curies |
| Strontium-90 | 64.3 curies |
| Plutonium-239 | 1.78 curies |
| Cerium-144 | 3,770 curies |
The first eight nuclear reactors at Hanford used large amounts of Columbia River water to cool the reactor cores. The water went through the reactors once before being returned to the Columbia River, even though the water contained radioactive materials. Radioactive materials that built-up inside the reactors were also regularly flushed loose and entered the Columbia River.
These eight reactors were operating at highest power between the late-1950s and mid-1960s. Contamination of the Columbia River was greatest during this time. The last of the eight reactors was shut down in January 1971.
HEDR now estimates that five radioactive substances account for most of the dose received from exposure to the Columbia River. They are arsenic-76, neptunium-239, phosphorus-32, sodium-24, and zinc-65 (Table 2).
People received exposure from the Columbia River by: eating contaminated fish and seafood; drinking contaminated water; swimming in or boating on the Columbia River; standing along the river shoreline or on a lawn irrigated with river water; and breathing dust blowing off exposed beaches or land irrigated with river water. Eating fish and seafood and drinking water were the main ways people were exposed to radiation from Hanford's reactors. Module 11 discusses the releases to and effects on the Columbia River.
| Arsenic-76 | 2,500,000 curies |
| Neptunium-239 | 6,300,000 curies |
| Phosphorus-32 | 230,000 curies |
| Sodium-24 | 12,000,000 curies |
| Zinc-65 | 490,000 curies |
See Module 11: Radionuclides in the Columbia River.
The separations plants at Hanford required large amounts of water. Millions of gallons of highly radioactive waste from these plants are currently stored in tanks at Hanford. Billions of gallons of less radioactive water, which were put into trenches and surface ponds, seeped into the ground. Some radioactive materials traveled through the soil and entered the groundwater. Radioactive wastes were sent directly into the groundwater through "injection wells" or shafts dug into the soil.
Tritium is most commonly found 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. HEDR believes there was little human contact with the contaminated groundwater in the past. If groundwater contamination from Hanford migrates under the Columbia River and contaminates water wells on the other side of the river in the future, this might pose a danger to the public.
