http://pbadupws.nrc.gov/docs/ML1012/ML101270439.pdf
Overview:
Tritium is a mildly radioactive type of hydrogen that occurs both naturally and during the operation of nuclear power plants. Water containing tritium and other radioactive substances is normally released from nuclear plants under controlled, monitored conditions the NRC mandates to protect public health and safety. The NRC recently identified several instances of unintended tritium releases, and all available information shows no threat to the public. Nonetheless, the NRC is reviewing these incidents to ensure nuclear plant operators have taken appropriate action and to determine what, if any, changes are needed to the agency's rules and regulations. The following information provides further basic information on tritium and other isotopes released from nuclear power plants, outlines the status of the unintended tritium leaks and the NRC's actions.
Introduction
This is a list of reactor sites that experienced a leak or spill to the environment at some time since initial startup. The list only includes those leaks or spills where tritium in the leak source or the groundwater sample was greater than 20,000 pCi/L. The term “leaks and spills” includes all types of non-routine releases in which tritium from reactor operation contacted the soil in an unintended fashion.
Source of Information
This information was compiled by NRC staff and is based on available records (e.g., Annual Effluent Reports, Annual Environmental Reports, Groundwater Questionnaires, Preliminary Notifications, Event Notifications, Licensee Event Reports (LERs), NRC Inspection Reports, Special Reports, and other documents submitted by the licensees to the NRC). Although the records search was extensive, extending back to the 1970s, the search was not all inclusive.
Purpose
The NRC has received many questions from the public, the news media, and politicians
concerning spills and leaks at power reactor sites. Although most of these questions were similarly focused on groundwater contamination, the questions were different enough to produce significant variations in the responses. This list is intended to be the best single response to those questions involving “numbers” such as:
• How many sites have had leaks or spills of radioactive material?
• What concentrations of tritium were involved?
• What are the current tritium concentrations at each of the sites?
Contents
The tritium concentrations listed are approximate historical maximums, and approximate current concentrations. Some numbers have been rounded off for clarity. Although there may be some data in the historical records showing concentrations slightly different than the values listed, the values shown provide a reasonable indication of the magnitude and extent of the historical leaks and spills as well at the current conditions at these sites.
The value listed as the “current conditions” lists the highest tritium concentration found in the environment, on facility property, at the current time or within approximately the last year. Although in many cases the actual current tritium concentrations will be less than the value indicated, this method provides a reasonable approximation of the plume concentration currently on each site.
Samples are collected from onsite and offsite locations. Samples are collected from both drinking water wells and non-drinking water sample points (e.g., storm drains, man holes, bore holes, piezometer tubes, monitoring wells, surface water, puddles, and rain water). All of these samples are evaluated for inclusion in this list. Although some values in the list exceed 20,000 pCi per liter, none of those samples were from a drinking water well or from a municipal drinking water system. In fact, although samples are collected from drinking water wells and municipal
drinking water systems, none of those samples have ever exceeded 20,000 pCi per liter. As a result, a value of 20,000 pCi/L in this list does not imply the drinking water standard in EPA’s Safe Drinking Water Act has been exceeded.
After a radioactive spill or leak, tritium is generally the first radionuclide to be identified in groundwater. This is because tritium travels through the soil faster than other radionuclides. Leaks and spills at some sites (e.g., Indian Point, Braidwood) involved nuclides other than tritium (e.g., Cobalt-60, Cobalt-58, Cesium-134, Cesium-137, Strontium-90, Nickel-63), but those radionuclides are not included in this list.
The current status of these sites reflects the most recently available information as of the date shown at the top of this page. This list will be revised as new information becomes available.
Significant Changes in this Version
• The current status of each site was reviewed and updated accordingly.
• Three reactor sites were added to the list.
• Some of the historical releases were updated based on recent information.
Summary
There are 65 locations in the United States where commercial nuclear power plants are
operating. Records indicate 41 of these sites have had leaks or spills that involved tritium in excess of 20,000 pCi/L at some time during their operating history. Sixteen sites are currently reporting tritium, from a leak or spill, in excess of 20,000 pCi/L. Although many sites have had leaks or spills involving tritium, no site is currently detecting tritium in the offsite environment, or in drinking water, in excess of 20,000 pCi/L. Tritium rapidly disperses and dissipates in the environment, and as a result, tritium from leaks and spills is typically not detected outside the facility boundary. The historical data indicates in only one instance, at Braidwood, was tritium from a leak or spill found in the offsite environment
in excess of 20,000 pCi/L. All samples from Braidwood since 2008 indicate tritium is no longer present in excess of 20,000 pCi/L in either the onsite or the offsite environment.
Conclusion
The existing complement of 104 power reactors, each operating for approximately 20-40 years, represents approximately 3,000 reactor years of operation. During that time, leaks and spills involving tritium have occurred at many commercial power reactors in the United States. This list demonstrates that in all of that time, and with all the leaks and spills that have occurred, no drinking water supply has exceeded the allowable level for tritium specified in EPA’s Safe Drinking Water Act
List of Historical Leaks and Spills At U.S. Commercial Nuclear Power Plants
more reading:
http://www.nrc.gov/reactors/operating/ops-experience/grndwtr-contam-tritium.html
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