Doctoral Dissertations

Date of Award

12-2025

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Nuclear Engineering

Major Professor

Lawrence H. Heilbronn

Committee Members

Eric W. Abelquist, Laurence F. Miller, Sarah E. Donaher

Abstract

The linear no-threshold (LNT) hypothesis and the ALARA (as low as reasonably achievable) principle are fundamental to setting release criteria for Decontamination and Decommissioning (D&D) projects. The LNT model assumes that any radiation dose, no matter how small, increases health risks, such as cancer, in a linear, proportional manner without a safe threshold. This can lead to selection of release criteria that are more stringent than federal requirements, potentially driving up project costs. This research presents a method to quantify the impact of lower release criteria on the relative cost of soil remediation and final status surveys (FSS).

Using Python scripts, a methodology was developed that uses existing radiological characterization data to calculate total contaminated soil volumes and surface areas for a range of release criteria. Unit cost factors for both soil remediation and FSS were then applied to these calculations. The remediation unit costs were based on a previous license termination plan's ALARA analysis and the FSS unit costs were derived using the MARSSIM methodology and available characterization data.

This methodology was tested on two case studies: the Rocky Flats Plant and the former Hematite fuel fabrication facility. The results show a power-function relationship where costs increase significantly as release criteria are lowered. Costs were normalized to a 0.25 mSv/y release criterion and compared with historical estimates identified in a Government Accountability Office report. The Rocky Flats case study demonstrated a more sensitive, inversely proportional cost response to reductions in the release criterion, consistent with previous estimates for the Nevada Test Site. The Hematite facility showed a less sensitive but still significant cost escalation.

These case studies illustrate a clear, direct relationship between project cost and the selected release criterion. The model developed can serve as a valuable tool for stakeholders to scope the relative costs of soil remediation and FSS for future D&D projects.

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