K West Basin Water Treatment System
Q-Metrics provided the thermal
and gas generation safety analysis for the water treatment system installed in
the K West Basin. The analysis demonstrated that the system temperatures
remained below 50°C during normal and
upset conditions and that the hydrogen gas concentration remained below 25% of
the lower
flammability limit. The work was conducted in support of Chem Nuclear Systems
and Duke Engineering in July and August of 1997. The system, which covered a
knockout pot, 10 settling tanks, the ion exchange module, the clarifier, and
three filtration units, filters and collects particulates and soluble
contaminants to be generated by the cleaning and loading of the 50,000 fuel
elements in the K West Basin. Without this equipment, the water clarity and
working conditions would deteriorate during the removal and cleaning of the fuel
elements. The system layout within the basin is illustrated below.
The thermal and gas generation
calculations involved working with project personnel to establish the
appropriate reaction rate equations for chemical heat and gas generation, the
bounding reaction areas for the
contents,
and the operational constraints to be applied to the analysis. Since the
filtration units contained a mixture of filtration medium and sludge, the
development of accurate effective thermal properties was critical to the
predictions of heat and gas generation rates. This calculation was further
complicated by the fact that the filtration medium varied in composition from
coarse to fine along the length of the unit. The effective thermal properties
for each layer within the filtration units was computed assuming porous medium
assumptions and the thermal properties for each material contained within that
layer. Normal and upset conditions were evaluated.
The analysis successfully demonstrated the safety of the proposed system design
for handling the water treatment within the K West Basin.