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Mallinckrodt Chemical Inc.

1.0 Site Identification

2.0 Site Status Summary

Mallinckrodt Chemical, Inc., has been operating at the St. Louis site since 1867, producing a wide range of products including metallic oxides and salts, ammonia, and organic chemicals. The St. Louis site, comprised of more than 50 buildings on approximately 43 acres, is subdivided into smaller areas, called plants, based on the similarity of operations being performed.

From 1942 through 1957, Mallinckrodt was under contract to the Manhattan Engineering District and the Atomic Energy Commission (MED-AEC) to extract and process uranium ore to produce various compounds for development of atomic weapons. Then, in 1961, the U.S. Nuclear Regulatory Commission (NRC) issued License No. STB-401 to authorize Mallinckrodt to extract columbium and tantalum (C-T) from natural ores and tin slags. From 1961 to 1974, Mallinckrodt purchased feedstock materials for C-T processing, which occurred from 1975 through 1985. C-T processing was shutdown from 1985 through early 1987, when Mallinckrodt began a 2-month pilot production run. During the pilot production run approximately 20,000 pounds of tin slag were processed, and approximately 6 Curie (Ci) of natural uranium isotopes and 19 Ci of natural thorium isotopes were contained in the ores and tin slags processed under License STB-401, as well as the byproduct materials produced in processing. In July 1993, the NRC amended Mallinckrodt's license to a possession only license for decommissioning and license termination.

Radiological contamination at the site resulted from MED-AEC and C-T processing activities. MED-AEC contamination is being removed by the U.S. Army Corps of Engineers (USACE) under the Formerly Utilized Sites Remedial Action Program (FUSRAP). USACE developed a preferred cleanup approach for the MED-AEC contamination, based on the data and findings presented in five documents:

• Remedial Investigation Report
• Baseline Risk Assessment
• Initial Screening of Alternatives
• Feasibility Study & Proposed Plan
• Record of Decision

Mallinckrodt submitted its "C-T Project Decommissioning Plan, Part 1," on November 20, 1997, followed by revisions on January 18, 2001. The ultimate goal of the C-T project decommissioning is to remediate those areas of the site associated with C-T production, to the extent necessary, to ultimately terminate License STB-401. Mallinckrodt has elected to decommission the C-T project areas of the site in two phases. In Phase I, completed in December 2004, Mallinckrodt decommissioned the buildings and equipment to the extent necessary to meet the NRC's guidelines for unrestricted release. Phase II will include remediating the building slabs and foundations, paved surfaces, and all subsurface materials to the extent that they can be released for unrestricted use. Mallinckrodt submitted its Decommissioning Plan for Phase II for NRC review and approval in May 2003; however, because of a number of legal and policy issues, that plan has not yet been approved. Public interest in the site is high; however, concern over decommissioning activities is low. The NRC staff has not identified any major offsite environmental issues that will not be addressed during remediation of the facility.

3.0 Major Technical or Regulatory Issues

Contaminants at the Mallinckrodt site are uranium isotopes (U-238, U-235, U-234) and progeny; thorium isotopes (Th-230, Th-232, Th-228) and progeny; radium isotopes (Ra-226 and Ra-228); and potassium (K-40). Although total uranium was detected in the filtered samples at elevated concentration, it was concluded that these detections do not present a groundwater ingestion hazard since the perched groundwater in the upper zone is not a drinking water source. As a result, the groundwater pathway was turned off for modeling purposes. Decommissioning at the site is taking place in two phases, and Mallinckrodt is requesting to remediate the site to ultimately meet the unrestricted release criteria established by Subpart E, "Radiological Criteria for License Termination," in Title 10, Part 20, of the Code of Federal Regulations (10 CFR Part 20), "Standards for Protection Against Radiation." In August 2007, Mallinckrodt submitted a license amendment for source removal in Plant 6W. The staff issued the license amendment for removal of unreacted ore (URO) from Plant 6W in May 2008, and that process is scheduled to be completed in July 2010.

4.0 Estimated Date For Closure

01/30/2012

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Monday, November 16, 2009