Validation of the SEPHIS Program for the Modeling of the HM Process

Technical Report · Thu Dec 17 04:00:00 EST 1998

DOI:https://doi.org/10.2172/4836· OSTI ID:4836

Kyser, E A

The SEPHIS computer program is currently being used to evaluate the effect of all process variables on the criticality safety of the HM 1st Uranium Cycle process in H Canyon. The objective of its use has three main purposes. (1) To provide a better technical basis for those process variables that do not have any realistic effect on the criticality safety of the process. (2) To qualitatively study those conditions that have been previously recognized to affect the nuclear safety of the process or additional conditions that modeling has indicated may pose a criticality safety issue. (3) To judge the adequacy of existing or future neutron monitors locations in the detection of the initial stages of reflux for specific scenarios.Although SEPHIS generally over-predicts the distribution of uranium to the organic phase, it is a capable simulation tool as long as the user recognizes its biases and takes special care when using the program for scenarios where the prediction bias is non-conservative. The temperature coefficient used by SEPHIS is poor at predicting effect of temperature on uranium extraction for the 7.5 percent TBP used in the HM process. Therefore, SEPHIS should not be used to study temperature related scenarios. However, within normal operating temperatures when other process variables are being studied, it may be used. Care must be is given to understanding the prediction bias and its effect on any conclusion for the particular scenario that is under consideration. Uranium extraction with aluminum nitrate is over-predicted worse than for nitric acid systems. However, the extraction section of the 1A bank has sufficient excess capability that these errors, while relatively large, still allow SEPHIS to be used to develop reasonable qualitative assessments for reflux scenarios. However, high losses to the 1AW stream cannot be modeled by SEPHIS.

• Research Organization: Savannah River Site (US)
• Sponsoring Organization: US Department of Energy (US)
• DOE Contract Number: AC09-96SR18500
• OSTI ID: 4836
• Report Number(s): WSRC-TR-98-00376
• Country of Publication: United States
• Language: English

Related Subjects

11 NUCLEAR FUEL CYCLE AND FUEL MATERIALS
CRITICALITY
FUEL REPROCESSING PLANTS
NEUTRON MONITORS
NITRIC ACID
POSITIONING
S CODES
SAFETY ANALYSIS
SOLVENT EXTRACTION
TBP
URANIUM RECYCLE