Minimal Serpent Coupling Script
The Minimal Serpent Coupling Script (MSCS) is a short (< 300 lines with comments) Python program intended to give a minimal working example of a wrapper program that can communicate with Serpent in the coupled calculation mode. MSCS provides a working example of externally coupled multi-physics simulations with Serpent and may be a good starting point for the users that are interested in running such simulations with Serpent.
Description
Files
MSCS.py
#############################################################
# #
# Minimal Serpent Coupling Script v 0.1 #
# #
# Created by: Ville Valtavirta 2016/05/06 #
# Modified by: Ville Valtavirta 2016/05/09 #
# #
#############################################################
import os
import signal
import time
# Path to Serpent executable
sssexe = '/home/vvvillehe/Serpent2/gittest/sss2'
#######################################################
# Create the Serpent input-file for this run #
# (process id or communication file must be appended) #
#######################################################
# Open original input for reading
file_in = open('./input','r')
# Open a new input file for writing
file_out = open('./coupledinput','w')
# Write original input to new file
for line in file_in:
file_out.write(line)
# Close original input file
file_in.close()
# Append signalling mode
file_out.write('\n')
file_out.write('set comfile com.in com.out\n')
# Append interface name
file_out.write('\n')
file_out.write('ifc cool.ifc\n')
# Close new input file
file_out.close()
####################################
# Write the initial interface file #
####################################
file_out = open('./cool.ifc','w')
# Write the header line (TYPE MAT OUT)
file_out.write('2 cool 1\n')
# Write the output line (OUTFILE NZ ZMIN ZMAX NR)
file_out.write('coolifc.out 10 -100 100 1\n')
# Write the mesh type
file_out.write('1\n')
# Write the mesh size (NX XMIN XMAX NY YMIN YMAX NZ ZMIN ZMAX)
file_out.write('1 -0.75 0.75 1 -0.75 0.75 10 -100 100\n')
# Write initial fuel temperatures and densities
for i in range(10):
file_out.write('-0.99 520.0\n')
# Close interface file
file_out.close()
################################
# Start the Serpent simulation #
################################
# Create a command string that will start the Serpent simulation
runcommand = sssexe+' -omp 3 ./coupledinput &'
# Execute the command string
os.system(runcommand)
#########################
# Picard iteration loop #
#########################
iterating = 1
while iterating == 1:
###################
# Wait for signal #
###################
sleeping = 1
while sleeping == 1:
# Sleep for two seconds
time.sleep(2)
# Open file to check if we got a signal
fin = open('./com.out','r')
# Read line
line = fin.readline()
# Close file
fin.close()
# Check signal
if int(line) != -1:
if int(line) == signal.SIGUSR1:
# Got the signal to resume
sleeping = 0
elif int(line) == signal.SIGUSR2:
# Got the signal to move to next time point
iterating = 0
sleeping = 0
elif int(line) == signal.SIGTERM:
# Got the signal to end the calculation
iterating = 0
sleeping = 0
else:
# Unknown signal
print "\nUnknown singal read from file, exiting\n"
# Exit
quit()
# Reset the signal in the file
file_out = open('./com.out','w')
file_out.write('-1')
file_out.close()
# Check if iteration has finished
if (iterating == 0):
break
###########################
# Read power distribution #
###########################
# Reset power distribution
P = []
# Open output file
file_in = open('./coolifc.out','r')
# Loop over output file to read power distribution
for line in file_in:
# Split line to values
strtuple = line.split()
# Store power
P.append(float(strtuple[8]))
###########################
# Calculate TH-solution #
###########################
# Reset TH-solution
T = []
rho = []
# Coolant specific heat capacity
cp = 4900 # J/(kg*K)
# Coolant mass flow rate
w = 0.3 # kg/s
# Put inlet temperature
T.append(520)
# Put inlet density
rho.append(0.813)
# Calculate temperatures at (nz+1) axial nodes
for i in range(10):
# Calculate next temperature
# T(i+1) = T(i) + P(i)/(w*cp)
Tnext = T[i] + P[i]/(w*cp)
# Store new temperature
T.append(Tnext)
# Calculate next density based on temperature
# Linear interpolation between
# T0 = 520, rho0 = 0.813
# T1 = 600, rho1 = 0.653
rhonext = 0.813 + (0.653 - 0.813)/(600.0 - 520.0)*(Tnext - 520.0)
# Store new density
rho.append(rhonext)
###########################
# Update interface #
###########################
file_out = open('./cool.ifc','w')
# Write the header line (TYPE MAT OUT)
file_out.write('2 cool 1\n')
# Write the output line (OUTFILE NZ ZMIN ZMAX NR)
file_out.write('coolifc.out 10 -100 100 1\n')
# Write the mesh type
file_out.write('1\n')
# Write the mesh size (NX XMIN XMAX NY YMIN YMAX NZ ZMIN ZMAX)
file_out.write('1 -0.75 0.75 1 -0.75 0.75 10 -100 100\n')
# Write updated fuel temperatures and densities
for i in range(10):
# Calculate density and temperature at this layer as an average
# of layer bottom and top values
Tnext = (T[i]+T[i+1])/2.0
rhonext = (rho[i]+rho[i+1])/2.0
# Write density and temperature at this layer
file_out.write('{} {}\n'.format(-rhonext, Tnext))
############################
# Signal Serpent (SIGUSR1) #
############################
file_out = open('./com.in','w')
file_out.write(str(signal.SIGUSR1))
file_out.close()
input
% --- Input for MSCS testing set title "Serpent-MSCS externally coupled calculation" % --- Fuel Pin definition: pin 1 fuel 0.4335 gas 0.442000 clad 0.502500 cool % --- Lattice (type = 1, pin pitch = 1.5): lat 10 1 0.0 0.0 1 1 1.5 1 % --- Boundary of the geometry (200 cm active length) surf 2 cuboid -0.75 0.75 -0.75 0.75 -100 100 % --- Cell definitions: cell 3 0 fill 10 -2 % Pin-cell cell 99 0 outside 2 % Outside world % --- Fuel material: mat fuel -10.424 tmp 1200.0 rgb 100 160 140 92235.03c -0.015867 92238.03c -0.86563 8016.03c -0.1185 % --- Cladding material: mat clad -6.55 rgb 200 200 200 40090.03c -0.98135 24052.03c -0.00100 26056.03c -0.00135 28058.03c -0.00055 50120.03c -0.01450 8016.03c -0.00125 % --- Gas gap: mat gas -1E-4 rgb 255 255 255 2004.06c 1.0 % --- Coolant (majorant density and TMS-limits for temperature): mat cool -0.990 tft 520 624 moder lwtr 1001 rgb 150 160 240 1001.03c 0.66667 8016.03c 0.33333 % --- Thermal scattering data for light water: % On-the-fly treatment for SAB-data between 474 K -- 624 K therm lwtr 0 lwj3.07t lwj3.09t lwj3.11t lwj3.13t % --- Reflective boundary conditions in XY set bc 3 3 1 % --- Neutron population and criticality cycles: set pop 10000 50 50 % --- Use fission source passing with 20 inactive cycles on % later iterations set fsp 1 20 % --- Maximum number of coupled calculation iterations set to 2 set ccmaxiter 2 % --- Total power for normalization (600 W/cm, unrealistically high): set power 120000.00
Setup
MSCS has been tested with Python 2.7.6 and Serpent 2.1.26.
- Save the contents of the MSCS.py file (above) to a file of the same name.
- Replace the absolute path to the Serpent executable on line 16 of MSCS.py.
- Save the contents of the input file to a file called input in the same directory where the MSCS.py file is located.
- Add some cross section libraries to the input-file using the set acelib input option.
- The test case is now ready to run.
Running
Note: Before running the MSCS you should familiarize yourself with finding and killing background processes in your operating system. Since MSCS runs Serpent as a background process, killing MSCS will not kill the Serpent process automatically.
Run the simulation from the testcase-folder using the command python ../MSCS.py
The output of the Serpent run will be printed to the terminal.
