Using Chemical and Process Modelling to
Design, Improve and Understand Effluent
Treatment Plant
We are a team of chemical engineers, chemists and materials
scientists who use a range of modelling and decision-making tools
to describe, aid understanding, and improve, plants and processes
throughout the nuclear industry. With our broad base of
experience, and strong experimental links, our knowledge and
technical capabilities have been applied through all stages of a
plant’s life cycle.
Plant and Process
Support
• Process Optimisation
• Problem Solving and Decision Support
Engineering Design
Support
• Static and Dynamic Flowsheeting
• Modelling Support to Engineering Consultancies
Modelling Products
• Bespoke Decision Support Tools
• Web-Based Models to Support Design and Process
Development
High-level flowsheeting is used to develop a dynamic model of the plant or process of interest.
Here is shown the stages of the Sellafield Ion eXchange Effluent treatment Plant (SIXEP)
This gives a structure to any experimental or modelling investigations, and provides a route to
feedback the fundamental science in a form useful to the plant.
Secondment
• Secondment into Customer Organisation
• Customer Secondment for Training and Development
Fundamental
Development
• Collaboration with Academic Links
• Nuclear Computing Facilities
• Technical Benchmarking
4000
Pond purge liquor from fuel storage ponds are
sent to SIXEP for treatment. There is a need to
predict future levels of radioactivity in this
liquor to allow strategic planning in relation to
feeds from other plants which will arise.
A computer model has been developed which
predicts such radioactivity levels due to leakage
from containers of corroded fuel. The model
has been validated against previous
radioactivity levels measured on plant and
indicates a good match. It is used to provide
regular updates to the SIXEP flowsheet.
Cs137 in pondwater (Bq/ml)
Feed
3500
3000
2500
2000
1500
1000
Plant Data
Model Data
500
0
2005
2006
2007
2008
2009
2010
2011
2012
Magnox Fuel Storage Pond
Settling
Tanks
2013
Year
Filtration
Sludge Settling Vessel
Particle
trajectory
v0
Reaction-Diffusion-Advection
Streamline
C S   C    qcC 

  Dc

t t x 
x 
x
B
Saturation indices of potential Mg-CO3 phases as a
function of pH as predicted by PHREEQC and
compared to plant and experimental data.
pH
Adjustment
Collector
A
C
Models based on
numerical solution
of concentration down
the ‘column’:
Pressure drop in
column from
clogging (g):
A - Interception
B - Sedimentation
C - Diffusion
(1) Activity
within sludge
particle
structure
Ion
Exchange
(2) Activity
release due
to dissolution
(3) Activity
release due to
desorption
PHREEQC modelling findings have shown that
calcium solubility from grout and likely
efflorescence solids is controlled by calcite.
Where a pH ≥ 11 and higher PCO2 atmosphere
appropriate for B30 pond conditions reduces
the calcium solubility to 1-2 ppm.
Pourbaix diagrams for (a) Pu and (b) U speciation – effect of
carbonate
Cs-137 Breakthrough
20.00
18.00
Plant Data
Model Predictions
16.00
Discharges, GBq/day
14.00
12.00
10.00
8.00
6.00
4.00
2.00
0.00
2005.5
2006
2006.5
2007
2007.5
2008
2008.5
Time, years
Contact: Dr Scott L Owens, Business Manager
T. +44 (0) 1925 289948
M. +44 (0) 7540 672847
In order to model the cation
exchange processes
occurring in zeolites it is
essential to describe the
diffusion rates of the
exchanging cations as well as
the cation-framework
interactions.
These properties cannot
always be accurately
measured experimentally
therefore Molecular
Dynamics simulations can
instead be performed in
order to study the atomic
level structure and
interactions of the zeolite
and cations.
E. [email protected]
Atomistic
modelling of
fission product
removal from
molten salt waste
by ion exchange
Which ‘cage’ material
is most suitable for
the application?
How do ions interact
and compete with
each other?
How does behaviour
differ with or without
water present?