ML060680387
| ML060680387 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Byron, Braidwood, Clinton, Quad Cities, LaSalle  |
| Issue date: | 03/09/2006 |
| From: | NRC/RGN-III |
| To: | |
| References | |
| FOIA/PA-2006-0130, FOIA/PA-2010-0209 | |
| Download: ML060680387 (4) | |
Text
NRC NEWS U.S. NUCLEAR REGULATORY COMMISSION 2443 Warrenville Road Lisle IL 60532 Web Site: http://www.nrc.gov E-mail: opa3@nrc.gov March 9, 2006 NRC REGION III TRITIUM INSPECTION ACTIVITIES NRC Region III (Chicago) is reviewing tritium-related issues at Illinois nuclear power plants after groundwater contaminated with tritium was discovered offsite at the Braidwood Nuclear Power Station in November 2005. Braidwood and the other nuclear plants in Illinois are operated by Exelon Generation Co.
Tritium is a radioactive form of hydrogen. Tritium occurs naturally in the environment in very low concentrations. Most tritium in the environment is in the form of tritiated water, which easily disburses in the atmosphere, water bodies, soil, and rock. Tritium is produced naturally in the upper atmosphere when cosmic rays strike air molecules. Tritium is also produced as a byproduct of the fission process in nuclear power reactors. According to the Environmental Protection Agency, tritium is one of the least dangerous radioactive materials because it emits very weak radiation and leaves the body relatively quickly. The EPA has established drinking water standards for tritium to minimize the risk of exposure to water containing tritium.
Braidwood Exelon has collected groundwater samples from numerous monitoring wells on and near the Braidwood site. The data confirms the migration of tritium-containing water from an area where leaks have occurred in a 42-inch diameter pipe which carries cooling water discharge to the Kankakee River.
This pipe, though usually carrying non-radioactive water, has also been used for the release of low-level radioactive effluent from the plant, which is permitted under limits and conditions imposed by the NRC. Significant leaks in the pipeline occurred in 1996, 1998, and 2000.
On Nov. 30, 2005, Exelon informed the NRC that it had detected elevated tritium levels in recently installed monitoring wells on the site and that tritium-bearing groundwater may have migrated off the site to the north.
The NRC promptly began inspection activities to assess the groundwater conditions and review Exelons activities in response to the problem. These inspection activities were carried out by radiation specialists from the Region III office as well as the two NRC resident inspectors assigned to the Braidwood site. The NRC collected and analyzed independent samples of some area residential wells and, in addition, analyzed split samples of groundwater collected by Exelon. The results of the NRC analyses have been consistent with Exelons laboratory results. Initial inspection findings, through Dec. 31, are contained in Inspection Report 05-10, which is available on the NRC web site (http:www.nrc.gov/NRR/OVERSIGHT/ASSESS/REPORTS/brai_2005010.pdf).
In mid-February the NRC began an additional inspection focusing on the historical leaks from the circulating water discharge line beginning in 1996 - what information was available at the time, what actions Exelon took, and what followup activities occurred. This inspection is scheduled to be completed in early March with the inspection report expected to be issued in early April.
Braidwood, like most nuclear plants, releases water containing low levels of radioactivity under controlled and monitored conditions. These releases have been halted since late November while the company reviews its release procedures and verifies the integrity of the pipeline to the Kankakee River (ADAMS ML060670040 and ML060660590). In addition to liquid radioactive effluents, nuclear plants also release gaseous radioactive effluents into the atmosphere in a controlled and monitored process.
Byron Because the Byron Nuclear Power Station has a circulating water discharge line similar to that at Braidwood, the NRC resident inspectors are monitoring Exelons activities there to determine what leakage may have occurred there and if there has been any possible groundwater contamination.
Exelon has identified measurable levels of tritium in standing water in the concrete vaults surrounding the vacuum breakers, the same types of valves which caused the leaks at Braidwood. The company is installing monitoring wells nearby to determine if there has been any migration of tritium-bearing water outside the vaults.
The NRC is collecting independent samples and/or split samples of residential drinking water wells and other groundwater wells in the Byron plant area to determine if there is any measurable tritium.
Dresden The NRC inspectors at the Dresden Nuclear Power Station are assessing a leak in an underground pipe which resulted in tritium-bearing water being released to a small area on the plant site - about 30 feet square. This leak, which was reported to the NRC on Feb. 10, appears to originate from an underground pipe that carries water from a large water storage tank into the plant. The leak was detected through the licensees existing, onsite groundwater monitoring program. Exelon replaced a portion of the pipe in 2004 when it developed a leak, and planned to replace the remainder of the pipe in June. The suspected pipe was isolated by closing valves and drained to prevent further leakage.
The licensees excavation, characterization, and corrective actions are ongoing.
Other Illinois Nuclear Plants NRCs resident inspectors at the other nuclear power plant sites in Illinois - LaSalle, Quad Cities, and Clinton - are also gathering information about how tritium-bearing water is handled on each site and whether there have been leaks or unplanned releases of tritium-bearing water in the past.
The NRC will also observe Exelons collection of certain groundwater samples at these plants, as well as Zion, and collect split samples for analysis by the NRCs contractor laboratory. These reviews and sample collection are part of the day-to-day NRC inspection activities at the plant and will not result in a separate inspection report. Any inspection findings will be documented in the resident inspectors quarterly reports which will be available on the NRC web site.
NRC Documents Online:
Preliminary Notifications with additional details on Braidwood, Dresden, and Byron:
http://www.nrc.gov/reading-rm/doc-collections/event-status/prelim-notice/ - Select 2005 for Braidwood, 2006 for Dresden and Byron NRC Inspection Reports http://www.nrc.gov/info-finder/reactor/ - Select the reactor site from the alphabetical list, and then select inspection reports from the list of links.
For additional information:
Jan Strasma, Public Affairs Officer 630/829-9663 - rjs2@nrc.gov Victoria Mitlyng, Public Affairs Officer 630/829-9663 - vtm@nrc.gov Roland Lickus, Chief, State and Government Affairs 630/829-9660 - rml2@nrc.gov US Nuclear Regulatory Commission Office of Public Affairs 2443 Warrenville Rd Lisle IL 60532