g-2, BLIP, and USTs Record of Decision

May 2007

g-2, BLIP, and USTs Record of Decision

g-2 Soil Cap

Background

Muon g-2 Experiment (AOC 16T)

The Muon g-2 experiment was conducted from 1997 through 2001 on an independent beam line originating from the Alternating Gradient Synchrotron (AGS) facility. The experiment investigated how the spin of a muon (subatomic particle) was affected as it moves through a magnetic field. The muon g-factor can not only be predicted to high precision, but also measured to equally high precision. Thus, a comparison of measurement and theory provided a sensitive test of the Standard Model of particle physics.

In November 1999, BNL detected tritium in the groundwater near the g-2 experiment at concentrations two times greater than the drinking water standard. An investigation into the source revealed that the tritium originated from activated soil shielding located adjacent to the g-2 target building. The soil became activated by the accelerator beam inadvertently striking one of the magnets in the target building which deflected it into nearby soil. Rainwater then leached tritium from the soil and carried it into the groundwater. The g-2 tritium plume is located entirely within the central portion of the BNL site and more than a mile north of the southern boundary.

Corrective actions were implemented starting in December 1999. They included re-focusing the beam to significantly reduce beam loss, improving beam loss monitoring, and the installation of a concrete cap over the activated soil area to prevent additional rainwater infiltration. Further, rainwater runoff was controlled and additional groundwater monitoring was conducted.

BLIP (AOC 16K)

The Brookhaven LINAC Isotope Producer facility (BLIP) has been in operation since 1972. It is located in the central portion of the BNL site and is a national resource for producing radioisotopes that are crucial in nuclear medicine for research and clinical use. The BLIP facility uses a beam of protons delivered from the LINAC to irradiate materials encased in small, disk-like targets. From inside the BLIP building the targets are lowered to the bottom of a 30-foot underground target shaft. During target irradiation neutrons are generated that pass through the soil beneath the BLIP building. The neutrons react with atoms already present in the soil to form radioactive elements. As a result, soil located beneath BLIP has become contaminated with several radioactive elements. Most of these elements are very short-lived and decay within a few days to a few months. However, tritium and sodium-22 have radioactive half-lives of 12.5 and 2.6 years, respectively, and have been found in the soil and groundwater near the BLIP.

In 1998, higher concentrations of tritium than previously recorded were found in a groundwater monitoring well south of the facility. Additional wells were installed and tritium concentrations of 53,000 pico curies per liter (pCi/L) were verified. Investigations determined that rainwater infiltration occurred along the BLIP foundation and penetrated the activated soil surrounding the BLIP target vessel. The tritium was carried into the groundwater. A number of corrective actions were implemented immediately. Downspouts for the buildings rain gutter system were repaired and reconfigured, the paved area south of the building was resealed, and a concrete cap was installed over the remaining areas around the building in 1998. In June 2000, to further protect groundwater a liquid silica grout was injected into the soil around the target to immobilize the tritium as part of a DOE technology demonstration project. In 2004, the LINAC to BLIP beam line was capped.

Underground Storage Tanks (AOC 12)

A total of 16 underground storage tanks (USTs) used to hold low-level radioactive liquid waste were included as Area of Concern (AOC) 12. Eight of the USTs were previously removed and closed out in other Records of Decision (RODs). The eight remaining, one each at Buildings 462, 527, 703, and 927 and two each at Buildings 463 and 931, were removed between 1988 and 1996 with oversight provided by the Suffolk County Department of Health Services. Soil sampling performed after the tanks were removed did not identify any additional environmental concerns.

Record of Decision

The Record of Decision for g-2 Tritium Source Area and Groundwater Plume, BLIP, and Former Underground Storage Tanks documents the remedial alternative selected for the g-2 tritium source area and groundwater plume, and describes the action taken for the activated soils at the BLIP and for eight former underground storage tanks.

The g-2 experiment and the BLIP facility are located in the central portion of the BNL site. The primary contaminants of concern are tritium and sodium-22 found in the soil and groundwater. The selected remedy for the g-2 source area and groundwater plume includes continued routine inspections, certifications and maintenance of the concrete cap and other storm water controls designed to protect the activated soils from rainwater infiltration. Continuing monitoring of the groundwater to verify the effectiveness of the storm water controls is required and contingency requirements have been developed should the tritium plume not attenuate as predicted by the groundwater model.

For BLIP, continued inspections and maintenance of the cap, groundwater monitoring, and institutional controls in addition to the work previously completed, will continue for as long as the soils remain a threat to groundwater quality. No further action is needed. The same finding was reached for the underground storage tanks. The closure work already completed under Suffolk County Sanitary Code Article 12 is the final action.

The g-2 Record of Decision was signed by the EPA on May 10, 2007.

Community Input

The opportunities for community input into cleanup of the BLIP began in September 1999 with the Notice of Availability of an Engineering Evaluation/Cost Analysis. A public comment period on the EE/CA ran from September 20 to October 19, 1999. An Action Memorandum (for a Removal Action so the contamination could be dealt with quickly) was completed and a Notice of Availability was published in May 2000.

A formal public comment period on the Record of Decision ran from October 12 through November 13, 2006. Information Sessions were held on October 18, 2006 and a Public Meeting was held on October 25, 2006.

The Brookhaven Executive Roundtable was updated regularly on the g-2 source area and BLIP.

BNLs Community Advisory Council also was kept informed of the cleanup. They received 10 presentations on the project between December 1999 and May 2007. During the final comment period the CAC submitted a Consensus Resolution calling for additional review and active remediation if the contingency requirements are triggered.

Documents / Links

Fact Sheet

Proposed Remedial Action Plan

g-2 Record of Decision