Tank Waste Remediation System (TWRS) Program


A vitrification melter is a key component of the processing system.


Probabilities of accidents postulated in a safety case versus actual accidents were used for recommending acceptable accident frequencies.




For more information, contact:
Yi-Ming Pan, Ph.D.
(210) 522-6640

Sponsor:  U.S. Nuclear Regulatory Commission
Principal Investigator:  Osvaldo Pensado, Ph.D.

Program Brief

Statement of Problem: Provide technical assistance and bases necessary for the development of regulatory framework and associated guidance that can be used to support regulation of TWRS-P Phase II waste solidification (vitrification) operations based on 10 CFR Part 70.

Approach and Accomplishments: This program was structured into two parts:

1) Developed technical documents that provided the most current information of the waste solidification plant operations and safety issues, chemistry of waste in tanks and molten glass, evaluation of plant consequences based on 10 CFR Part 70 and standard review plan for TWRS.

2) Assisted the U.S. Nuclear Regulatory Commission staff in technical and regulatory reviews of Department of Energy (DOE) contractor documents, identified technical uncertainties and potential safety issues, and performed independent evaluations of proposed technologies or calculations used by the DOE contractor to support the safety case. This task included review of (i) process flow diagrams and designs, (ii) radionuclide inventories in tanks and criticality analyses, (iii) preliminary hazard analysis, (iv) initial safety analysis, (v) design safety features such as hydrogen generation in waste tanks, (vi) fire hazard analysis, (vii) management of risks posed by explosive and chemical hazards such as steam or sugar dust explosions and nitrate/organic reactions, (viii) preliminary design basis events, (ix) compliance with risk goals and project reliability data.

CNWRA® staff with experience in high-level waste solidification process design and operations, fire technology, health physics, risk analysis, corrosion engineering, chemical engineering, facility design engineering, nuclear criticality, and performance assessment were used to accomplish the task.

Client Benefits: The concerted efforts of a multi-disciplinary team at CNWRA provided, on schedule, evaluations and recommendations on technical uncertainties and potential safety issues associated with the proposed technologies or calculations used by the DOE contractor to support the safety case.


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August 07, 2014