As the Cold War grinds to a halt, the U.S. is forced to turn its attention from the production of nuclear weapons to the cleanup of the nuclear weapons complex and other sites contaminated by radioactivity. One of the common buzzwords from this new period is "D & D," which is not a fantasy game (one hopes) but "Decontamination and Decommissioning". Decontamination is the "cleaning up" process in which radioactive contamination at a site is reduced to acceptable levels for future public use. For example, by scraping up contaminated soil, consolidating and storing radioactive materials appropriately, and taking other measures, radioactive contamination at a site may be lessened or eliminated. Decommissioning is the process of removing a facility from service, "cleaning up" a site and terminating a license.

Decommissioning at many sites is routine, straightforward and does not involve residual contamination (contamination left over after the clean-up process). For instance, sites such as cancer treatment centers where radioactive materials are used in "sealed sources" can be decommissioned simply by removing the sealed source, leaving a clean site.

In contrast, some sites have soils and structures with considerable levels and volumes of contaminated soil, water, and/or buildings. Yet there are no comprehensive clean-up standards governing the decommissioning, clean-up and remediation of radioactively contaminated sites in the United States. There is a patchwork of guidelines and standards covering some issues and situations, but the vast majority of problems have yet to be addressed. The centerfold explains the current status of cleanup standards for decommissioning.

The difference between guidelines and standards lies in their legal power. Standards (also called "regulations") have been officially promulgated with public comment and have the force of law. Guidelines, on the other hand, are generally created on an ad hoc basis. They may assume the force of standards for specific sites if the concerned agency arrives at an agreement with the site's owner.

Present guidelines and standards do not cover risks from disposal or wastes resulting from cleanup; they only apply to risks from residual contamination after a site has been cleaned up, and to the risks for clean-up operations themselves.

The centerfold describes the guidelines of the Environmental Protection Agency (EPA), and the Nuclear Regulatory Commission (NRC) as they apply to various sites that are currently undergoing decommissioning and clean-up.

Currently there are five sets of guidelines or standards:

1. EPA standards on radium contamination near uranium mills;
2. EPA guidelines limiting soil contamination of transuranics (elements of higher atomic number than uranium);
3. Nuclear Regulatory Commission (NRC) guidelines for decommissioning uranium and thorium processing sites;
4. NRC residual surface contamination guidelines; and
5. EPA's drinking water standards.

These guidelines and clean-up standards have been split into three tables in the centerfold of this issue. The tables show the maximum level of contamination in the soil, water or surface (of buildings or equipment) at a given site. The text below explains the five broad categories of guidelines or standards.

1. Radium near uranium mills¹

Under the Uranium Mill Tailings Radiation Control Act (UMTRCA) of 1978, the EPA sets a limit of 5 picocuries of radium-226 per gram of soil (in addition to background levels)² for the top 15 centimeters of soil. For soil 15 centimeters and below, the limit is 15 picocuries per gram, in addition to background.³ Background levels are generally in the range of 1 to 2 picocuries per gram. These regulations only apply to sites recognized as falling under UMTRCA, though they may be applied to other sites, as determined on a site-by-site basis.

2. Transuranium elements contamination

EPA recommends that a reasonable "screening level" for transuranic elements (elements heavier than uranium) could be reached by a soil contamination of no more than 0.2 microcuries per square meter for samples collected at the surface to a depth of 1 centimeter and for particle sizes under 2 millimeters. This level of contamination is derived from a continuous annual dose rate of 1 millirad per year to the lung. According to EPA, this dose rate would result in 10 premature cancer deaths for a population of 100,000. The continuous annual dose rate to the bones would be about 3 millirad per year, resulting in about 6 premature cancer deaths for the same population.⁴

In 1981 the Nuclear Regulatory Commission came out with a paper known as the "Branch Technical Position"(BTP)⁵ which gave guidance for disposal or on-site storage of soil contaminated with thorium and uranium. These guidelines were developed in particular for sites where large volumes of contamination existed but where radioactivity was believed to be low enough to justify disposal.

Of the five original disposal and storage options in the BTP, only the first 2 options (requiring release of the site for unrestricted use) have been retained in the 1992 "Action Plan" (see "SDMP" sites, below). These options are known as "option 1" and "option 2." Under option 1 there are no restrictions regarding the method of burial, whereas under option 2 the material has to be buried at a depth of at least 4 feet below the surface if it can be demonstrated that there will be no migration of contamination. Natural uranium is not included in option 2 because of possible radon-222 (a uranium daughter) emanations, which would result in higher-than-allowable exposure of individuals in private residences if houses were built over buried materials.

4. Building and Equipment Contamination⁶

As with soil contamination, the NRC requires the licensee to make a reasonable effort to eliminate residual contamination from the site. Upon request the NRC may allow the licensee to give up ownership of buildings and equipment with contamination in excess of the limits specified. In that case, the licensee must give detailed information on the nature, location and degree of residual contamination and show that this contamination is unlikely to result in health and safety risks to the public.

Along with acceptable surface contamination levels, the NRC gives instructions for assessing levels of contamination for the interior of equipment not accessible to measuring instruments. The inside of a pipe, for example, must be assessed in this way, since the radioactivity within the pipe will not be directly measured.

5. Water contamination⁷

The NRC proposes that EPA's maximum contaminant level standards for radionuclides in public water (cited in EPA's "National Primary Drinking Water Standards"⁸) should be used for protection of surface water and groundwater. New standards have been proposed by EPA for the radionuclides.⁹ The new standards are scheduled to be put into force on April 30, 1995.

SDMP Sites

The NRC provided decommissioning guidance in the 1990 "Site Decommissioning Management Plan" (SDMP) and in the April 1992 document "NRC Action Plan to Ensure Timely Cleanup of SDMP Sites." Both documents, published as "NUREG-1444" in October 1993, provide a cleanup strategy for sites where no production operations are taking place and which meet certain criteria, among them: 1) there are large amounts of contaminated soil that are difficult to remediate, and 2) there is contamination or potential contamination of the groundwater from on-site wastes. The five standards and guidelines listed above apply to these sites.

Nuclear power reactors and thorium mills are excluded form this plan, since they are already covered by separate regulations. The five standards and guidelines listed above (excluding number 1, "radium near uranium mills") apply to these sites.

The Future of Cleanup

In addition to the cleanup standards described above, the Department of Energy (DOE) has dose standards in effect to protect the public from DOE facilities still in operation. These standards do not currently apply to cleanup, or even to low-level waste disposal for materials with half-lives in the hundreds of years or more. How these standards may be applied to future cleanup operations of DOE sites is unclear.

As the centerfold shows, there are some proposed standards for water, but not for soil or surfaces. The process of developing standards is a complex one, potentially involving a number of approaches. For example, standards may be based on risk or dose limits, limits on concentration of radionuclides, or a combination of these methods.

The EPA currently plans to publish draft cleanup standards in the fall of 1994 and to release its final standards in the fall of 1995. The NRC "staff draft" of proposed clean-up standards would establish a dose limit of 15 millirem/year, with a target of 3 millirem/year, and are in sharp contrast to the 170 millirem/year dose allowed under Option 2 in the BTP. Until that time, cleanup will rely on the standards and guidelines listed in the centerfold.

Mahoney, K., and Murakami, L. 1993. Farewell to Arms: Cleaning Up Nuclear Weapons Facilities. National Conference of State Legislatures: Denver, CO and Washington, DC. $15.00. Call (303) 830-2200.

Makhijani, A. and Saleska, S. 1992. High-level Dollars, Low-level Sense. A report for the Institute for Energy and Environmental Research. Apex Press: New York. Send a check for $15.00 to: IEER, 6935 Laurel Ave., Takoma Park, MD 20912.

U.S. Environmental Protection Agency. 1993. Issues Paper on Radiation Site Cleanup Regulations. (EPA 402-R-93-084) September 1993. Office of Radiation and Indoor Air: Washington, DC. Call (202) 233-9354.