This report was .prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, make any warranty, express or implied, or assumes a n y legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by t h e United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. DISCLAIMER Portions of this document may be illegible in electronic image products. Images are produced from the best available original document. Summary As part of its ongoing efforts to reduce doses to workers to levels as low as reasonably achievable (ALARA), Westinghouse Hanford Company (WHC) tasked the Health Protection Department of the Pacific Northwest Laboratory (PNL) to review operations at the 105 K-East Fuel Storage Basin (105 K-East). This review included both routine operations and a proposed campaign to encapsulate N-Reactor fuel stored there. This report summarizes the results of PNL's reviews of policy, procedures, and practices for operations at 105 K-East as well as an evaluation of the major sources of occupational radiation exposures. Where possible, data previously collected by WHC and its predecessors were used. In addition, PNL staff developed a threedimensional model of the radiological environment within 105 K-East to assess the relative contributions of different radiation sources to worker dose and to provide a decision tool for use in evaluating alternative methods of dose rate reduction. The model developed by PNL indicates that for most areas in the basin the primary source of occupational radiation exposure is the contaminated concrete surfaces of the basin near the waterline. Basin cooling water piping represents a significant source in a number of areas, particularly the Technical Viewing Pit. This report contains specific recommendations to reduce the impact of these sources of occupational radiation exposure in 105 K-East. Other recommendations to reduce doses to workers during activities such as filter changes and filter sampling are also included. .

Fourteen nuclear criticality accidents that occurred in Russia between 1953 and 1997 are described. These accidents are significant because of the loss of control of special nuclear material and the resultant radiation doses to personnel, potential damage to equipment, and release of radioactive material to the workplace and the environment. A qualitative analysis of the causes and contributing factors to these accidents is presented along with a description of the radiation health effects to workers. The primary cause of most of these accidents was inadequate design that allowed the use of process equipment that did not preclude nuclear criticality on the basis of geometry. Personnel errors and violations of procedures were major contributing factors to these accidents.

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SummaryThis report provides a proposed residual contamination guide (RCG) for the 324 Building B-Cell Cleanout Project, Phase 1, at the Hanford Site. The RCG is expressed as a fiaction of the amount of highly dispersible radioactive material that would result in offsite doses equal to the Pacific Northwest Laboratory radiological risk guidelines following the worst credible accident scenario for release of the holdup material. The proposed RCG is lo-' to lo2 of the PNL radiological risk guidelines.As part of the development of the RCG, a number of factors were considered. These include the need to provide an appropriate level of flexibility for other activities within the 324 Building that could contribute to the facility's overall radiological risk, uncertainties inherent in safety analyses, and the possible contribution of other 300 Area facilities to overall radiological risk. Because of these factors and the nature of the cleanout project, the RCG is expressed as a range rather than a point value. This report also provides guidance on determining conformance to the RCG, including inspection and measurement techniques, quality assurance requirements, and consideration of uncertainty.