Davidson, Greg | Engineering Papers

DOE OSTI2023

Postclosure Criticality Analysis Results

The United States Department of Energy’s (DOE) Office of Nuclear Energy’s Spent Fuel and Waste Science and Technology Campaign seeks to better understand the technical basis, risks, and uncertainty associated with the safe and secure disposition of spent nuclear fuel (SNF) and high-level radioactive waste. Commercial nuclear power generation in the United States has resulted in thousands of metric tons of SNF, the disposal of which is the responsibility of DOE (Nuclear Waste Policy Act of 1982, as amended). Any repository licensed to dispose of SNF must meet requirements regarding the long-term performance of that repository. The evaluation of long-term performance of the repository may need to consider the SNF achieving a critical configuration during the postclosure period. Of particular interest is the potential for this situation to occur in dual-purpose canisters (DPCs), which are currently licensed and being used to store and transport SNF but were not designed for permanent geologic disposal. DOE has been considering disposing of SNF in DPCs to avoid the costs and worker dose associated with repackaging the SNF currently stored in DPCs into repository-specific canisters. This report examines the consequences of postclosure criticality to provide technical support to DOE in developing a disposal plan.

12 MANAGEMENT OF RADIOACTIVE AND NON-RADIOACTIVE W↗

NASA NTRS2004

Performance as Promised: How the Chandra X-ray Observatory Accomplished One of Nasa's Most Challenging Missions for Billions of Dollars Less than Originally Planned

As the nation looks toward bold new ventures in space, the Chandra X-ray Observatory program offers an example of how billion-dollar missions can be successfully developed within tightening fiscal constraints. Chandra experienced many of challenges facing bold space programs (state-of-the-art technical requirements and budget-induced slips and restructurings), and yet the Chandra team achieved nearly all the originally envisioned performance for dramatically lower cost. This was accomplished by a combination of team- work, systems engineering, advanced technology insertion, and effective approaches for program implementation. A thorough tradeoff of science utility vs. cost led to the selection of a highly elliptical orbit with uncrewed robotic delivery, deployment, and maintenance. Progressive, focused technology demonstrations were accomplished prior to commitment of major resources to critical elements of the system design, such as the high resolution mirror assembly (HRMA). Pathfinder hardware was developed to reduce risks. A variety of schedule risk reduction measures were implemented and resulted in the X-ray calibration taking place exactly within five days of its originally planned date after after five years of development. The team worked together in an effective manner to contain requirements creep. reductions such as the ACIS-2 chip device. It is estimated that the above combination of measures achieved the avoidance of over $4B in costs, while enabling a highly successful mission.

Davidson, Greg↗