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1999 AIRNET Data Evaluation
This page contains data summaries for Airnet stations that exceeded evaluation criteria in 1999. These data and their discussion appear in the Laboratory's annual Environmental Surveillance Report.
Americium/Plutonium
1999 Americium and Plutonium Data Findings & Analysis
- Station 34 at TA-54, Area G: 1st and 2nd Quarter
- The 1999 Quarter 1 air concentrations at station #34, at the northeast corner of Area G were elevated above normal. The concentrations of 241Am (24 aCi/m3) and 239Pu (206 aCi/m3) were well above the six-year averages for these radionuclides of 5 and 19 aCi/m3, respectively. Discussions with operations staff at Area G revealed the following.
- On March 15, 1999, a 55-gallon drum was retrieved as part of the Transuranic Waste Inspectable Storage Project (TWISP) at TA-54. During inspection, a small hole was found on the bottom and alpha contamination was detected. Surface contamination was removed and the drum was sealed within a second drum. However, before the contamination was remediated, small amounts of radionuclides were released to the air. These releases caused increased concentrations at station #34, which is very close to the operations. If the releases had been large or widespread, we would have seen increases at other air monitoring stations nearby.
- Radiologically engineered controls were instituted to help minimize future releases to the air during these activities. These features included:
- In addition to the top and sides, the bottom surface of all drums is now checked for contamination throughout the retrieval and drum washing process.
- All drums that are suspected of being contaminated are immediately contained (bagged) in heavy plastic.
- Formal procedures are being updated to address these operational changes.
- Workers have been trained to all adopted operational changes.
- Since March 15, Area G staff have been retrieving drums using enhanced engineering controls to help reduce contamination release. In addition, continuous local air sampling, and enhanced area swiping (to search for contamination) are performed to determine effectiveness of the contamination controls.
- In spite of these mitigation measures, air concentrations remained elevated during Quarter 2, with 241Am and 239Pu concentrations of 265 and 197 aCi/m3, respectively. Additional mitigation measures are being evaluated by the operations group and we will continue to evaluate ambient air monitoring results as they become available.
Tritium
1999 Tritium Data Findings & Analysis
- County Landfill: January and February
- Investigation levels for tritium were exceeded at the County Landfill during the last 2 weeks of January and the first two weeks of February. The highest concentration measured was 9 pCi/m3, which would result in a concentration less than 0.06 mrem/yr. No cause for these elevated concentations was identified. Following this 4 week period, concentrations were at typical levels for the remainder of the year.
- TA-21: December
- In December 1999, clean-up activities at the Tritium Science and Fabrication Facility (TA-21-209) produced higher than average tritium emissions. One on-site station (#75) recorded a concentration of 22.5 pCi/m3, exceeding an investigation level, and several nearby stations in the townsite measured higher than normal air concentrations. This concentration at station #75 would result in a dose of less than 0.2 mrem/yr.
- Prior to initiation of these operations, a review of impacts was conducted by all environmental groups. As a result of this review, LANL air quality specialists worked with facility personnel to determine potential levels of emissions and to set limits on annual emissions. The clean-up operations are well within these limits and are considerably less than regulatory limits.
- TA-33
- From the end of 1998 through 1999, decontamination and decommissioning operations at TA-33, Bldg 86 produced increased tritium emissions that were detected by the AIRNET system. These operations, which were exhausted through a monitored stack, included characterization and depressurization of formerly used lines and vessels, were necessary prior to the building being demolished.
- These emissions resulted in exceedances of investigation levels at several stations in the vicinity of TA-33, Bandelier, and White Rock during the first quarter, in July, and in September. Peak concentrations of 14 pCi/m3 were recorded at the Bandelier AIRNET station in January. This concentration would result in a dose of less than 0.1 mrem/yr.
- Prior to initiation of these operations, a review of impacts was conducted by all environmental groups. As a result of this review, LANL's air quality specialists worked with facility personnel to determine potential levels of emissions and to set limits on annual emissions. The decontamination and decommissioning operations are well within these limits and are considerably less than regulatory limits.
Plutonium
1999 Plutonium Data Findings & Analysis
- Station 7: 3rd and 4th Quarter
- During the 3rd and 4th quarter of 1999, elevated concentrations of 239Pu were measured at Station #7 (Shell Station) in the townsite. These higher measurements (12.6 and 14.0 aCi/m3 respectively) appear to have been caused by soil disturbances associated with nearby construction activity. The construction is taking place in a former Laboratory technical site (TA-1) with contaminated soil that was subsequently remediated. Undoubtedly trace amounts of contamination remained after clean-up which have been re-suspended by the recent construction activity. If these concentrations had been measured for an entire year, the dose impact would be 0.07 mrem. Elevated 234U and 238U concentrations were also measured at this location during the fourth quarter, further demonstrating construction related increases in re-suspended particulate matter.
- Station 45 TA-54, Area G: 4th Quarter
- During the fourth quarter of 1999, an elevated 239Pu concentration was recorded at Station 45 at TA-54, Area G. The concentration of 52 aCi/m3 was the highest value recorded during 1999, but was similar to the highest values recorded in 1997 and 1998 at this station. The probable cause of this elevated value is re-suspension of residual soil contamination at the eastern end of Area G.
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