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Mallinckrodt Chemical Inc.

1.0 Site Identification

2.0 Site Status Summary

The Mallinckrodt Chemical, Inc., (Mallinckrodt) site has been in operation since 1867 and has produced a wide range of products. The St. Louis Plant, comprised of over 50 buildings on approximately 43 acres, is subdivided into smaller areas, called plants, based on the similarity of operations being performed. In addition to the extraction of columbium and tantalum carried out under NRC license STB-401, various uranium compounds were extracted under contract to the Manhattan Engineering District and the Atomic Energy Commission (MED-AEC). Remediation of MED-AEC radiological constituents is currently being performed under the DOE's FUSRAP by USACE.

Mallinckrodt has been operating at the St. Louis Plant since 1867 producing various products including metallic oxides and salts, ammonia, and organic chemicals. From 1942 to 1957, Mallinckrodt was under contract with the Manhattan Engineering Project and the Atomic Energy Commission (MED-AEC) to process uranium ore to produce uranium for development of atomic weapons. In 1961, Mallinckrodt was issued License No. STB-401 to extract columbium and tantalum (C-T) from natural ores and tin slags. From 1961 to 1974, Mallinckrodt purchased feed materials for C-T processing. Processing occurred from 1975 to 1985. The ores and processing byproduct materials contained uranium and thorium isotopes. C-T processing was shutdown from 1985 through early 1987, when Mallinckrodt began a two month pilot production run. During the pilot production run approximately 20,000 pounds of tin slag were processed. In July 1993, NRC amended Mallinckrodt's license to a possession only license for decommissioning and license termination. Approximately 6 Ci of natural uranium and 19 Ci of natural thorium isotopes were contained in the ores and tin slags processed under License STB-401. Background: 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: (1) Remedial Investigation Report; (2) Baseline Risk Assessment; (3) Initial Screening of Alternatives; and (4) Feasibility Study & Proposed Plan, and (5) Record of Decision. On November 20, 1997, Mallinckrodt Chemical Inc. (Mallinckrodt) submitted the "C-T Project Decommissioning Plan, Part 1," with revisions submitted 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, Mallinckrodt decommissioned the buildings and equipment to the extent necessary to meet NRC's guidelines for unrestricted release. Phase II will include the remediation of the building slabs and foundations, paved surfaces, and all subsurface materials. Mallinckrodt submitted the DP for Phase II to the NRC for review and approval in May 2003. Due to a number of legal and policy issues, the DP has not yet been approved. Public interest in the site is high, however, concern over decommissioning activities is low. The staff has not identified any major off-site 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: U-238; U-235; U-234 and progeny; Th-230; Ra-226; Th-232; Th-228 and progeny; Ra-228; and 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 Mallinckrodt site is taking place in two phases. Phase 1 addressed decommissioning of the buildings and equipment. Phase 1 was completed in December 2004. Phase II will include the decommissioning of the building slabs and foundations, paved surfaces, and all subsurface license related materials to the extent that they can be released for unrestricted use. Mallinckrodt is requesting to remediate the site to ultimately meet the unrestricted release criteria of 10 CFR Part 20, Subpart E. In August 2007, Mallinckrodt submitted a license amendment for source removal in plant 6W. The staff expects to issue the license amendment for removal of URO from Plant 6W in April 2008.

4.0 Estimated Date For Closure

05/01/2010

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Monday, April 14, 2008