Hi all,
I wrote a code to calculate the dose rate. However, when I change the distance from the source to the detector, the dose rate does not change with the distance. I just tried to get the distance by changing the source space. Could you help me?
Thank you
…
Create the dectector
--------------------
det_rect_prism = openmc.model.rectangular_prism(5.0, 10.0, axis=‘z’, origin=(0.0, 0.0))
det_zmin = openmc.ZPlane(z0 = -10, boundary_type = ‘transmission’)
det_zmax = openmc.ZPlane(z0 = +0, boundary_type = ‘transmission’)
detector = det_rect_prism & +det_zmin & -det_zmax
detector_cell = openmc.Cell(fill= cesium_iodide, region=detector)
Create a source sphere
----------------------------------------------------------------------------
source = openmc.Sphere(x0=+30.0, y0=0.0, z0=0.0, r=2.0, name=‘Source Container’)
source_cell = openmc.Cell(fill=None, region=-source)
Create the external environment
--------------------------------
sphere = openmc.Sphere(x0=30.0, y0=0.0, z0=0.0, r = 80, boundary_type = ‘vacuum’)
environment = -sphere & ~detector & +source
environment_cell = openmc.Cell(fill=air, region=environment)
universe = openmc.Universe(cells=[environment_cell, detector_cell, source_cell])
universe.plot(width = (20.0,20.0),basis = ‘xz’)
geometry = openmc.Geometry(universe)
geometry.export_to_xml()
Specify the source
#-------------------
source = openmc.Source()
source.space = openmc.stats.Point(xyz=(60, 0, 0))***
source.angle = openmc.stats.Isotropic()
This is a Co60 source, see the task on sources to understand it
source.energy = openmc.stats.Discrete([1.1732e6,1.3325e6], [0.5, 0.5])
source.particle = ‘photon’
source.strength = 1.0
settings = openmc.Settings()
settings.run_mode = ‘fixed source’
settings.source = source
settings.batches = 20
settings.particles = 100000
settings.export_to_xml()
number_bins = 101
bins_both = np.linspace(0, 1e6, number_bins)
energy_function_filter_n = openmc.EnergyFunctionFilter(energy_bins_n, dose_coeffs_n)
energy_function_filter_p = openmc.EnergyFunctionFilter(energy_bins_p, dose_coeffs_p)
photon_particle_filter = openmc.ParticleFilter([“photon”])
surface_filter = openmc.SurfaceFilter(sphere)
tallies = openmc.Tallies()
dose_tally = openmc.Tally(name=“dose_tally_on_surface”)
dose_tally.scores = [“current”]
dose_tally.filters = [
surface_filter,
photon_particle_filter,
energy_function_filter_p,
]
tallies.append(dose_tally)
model = openmc.model.Model(geometry, materials, settings, tallies)
!rm *.h5
sp_filename = model.run()
import math
open the results file
sp = openmc.StatePoint(sp_filename)
access the tally using pandas dataframes
tally = sp.get_tally(name=‘dose_tally_on_surface’)
df = tally.get_pandas_dataframe()
tally_result = df[‘mean’].sum()
tally_std_dev = df[‘std. dev.’].sum()
convert from the tally output units of pSv cm² to pSv by dividing by the surface area of the surface
dose_in_pSv = tally_result / (4 * math.pi * math.pow(80, 2))
source_activity = 114190 # in decays per second (Bq)
emission_rate = 2 # the number of gammas emitted per decay which is approximately 2 for Co60
gamma_per_second = source_activity * emission_rate
dose_rate_in_pSv = dose_in_pSv * gamma_per_second
print results
print('The surface dose = ', dose_rate_in_pSv, ‘pico Sv per second’)
