CAD geometry running problem

User Support
1

I have created a geometry in cubit, the cylinder shaped fuel is actually enclosed in a water domain. The geometry has successfully converted into h5m file. The code is given below:
import openmc

from IPython.display import Image
from matplotlib import pyplot as plt

materials

u235 = openmc.Material(name=“fuel”)
u235.add_nuclide(‘U235’, 1.0, ‘ao’)
u235.set_density(‘g/cc’, 11)

water = openmc.Material(name=“water”)
water.add_nuclide(‘H1’, 2.0, ‘ao’)
water.add_nuclide(‘O16’, 1.0, ‘ao’)
water.set_density(‘g/cc’, 1.0)
water.add_s_alpha_beta(‘c_H_in_H2O’)
materials = openmc.Materials([u235,water])

dagmc_univ = openmc.DAGMCUniverse(filename=‘bal4.h5m’, auto_geom_ids=True, auto_mat_ids=True)
bounding_box = openmc.rectangular_prism(20,20,boundary_type=‘reflective’)

cell = openmc.Cell(region=bounding_box, fill=dagmc_univ)
geometry = openmc.Geometry([cell])

settings = openmc.Settings()
settings.batches = 120
settings.inactive = 2
settings.particles = 1000

model = openmc.Model(geometry=geometry, materials=materials, settings=settings)
model.export_to_model_xml()

p = openmc.Plot()
p.width = (25.0, 25.0)
p.pixels = (400, 400)
p.color_by = ‘material’
p.colors = {u235: ‘yellow’, water:‘red’}
openmc.plot_inline(p)

It shows problem:

WARNING: Particle 144 underwent maximum number of events.
WARNING: Particle 390 underwent maximum number of events.
WARNING: Particle 279 underwent maximum number of events.
WARNING: Particle 643 underwent maximum number of events.

Even I have changed the boundary_type to vacuum but then it shows problem like:

====================> K EIGENVALUE SIMULATION <====================

Bat./Gen. k Average k
========= ======== ====================
1/1 0.03451

WARNING: The shared fission bank is full. Additional fission sites created in
this generation will not be banked. Results may be non-deterministic.
WARNING: The shared fission bank is full. Additional fission sites created in
this generation will not be banked. Results may be non-deterministic.
WARNING: The shared fission bank is full. Additional fission sites created in
this generation will not be banked. Results may be non-deterministic.
WARNING: The shared fission bank is full. Additional fission sites created in
this generation will not be banked. Results may be non-deterministic.
WARNING: The shared fission bank is full. Additional fission sites created in
this generation will not be banked. Results may be non-deterministic.
WARNING: The shared fission bank is full. Additional fission sites created in
this generation will not be banked. Results may be non-deterministic.
WARNING: The shared fission bank is full. Additional fission sites created in
this generation will not be banked. Results may be non-deterministic.
WARNING: The shared fission bank is full. Additional fission sites created in
this generation will not be banked. Results may be non-deterministic.
WARNING: The shared fission bank is full. Additional fission sites created in
this generation will not be banked. Results may be non-deterministic.
WARNING: The shared fission bank is full. Additional fission sites created in
this generation will not be banked. Results may be non-deterministic.

WARNING: The shared fission bank is full. Additional fission sites created in
this generation will not be banked. Results may be non-deterministic.
WARNING: The shared fission bank is full. Additional fission sites created in
this generation will not be banked. Results may be non-deterministic.
WARNING: The shared fission bank is full. Additional fission sites created in
this generation will not be banked. Results may be non-deterministic.
WARNING: The shared fission bank is full. Additional fission sites created in
this generation will not be banked. Results may be non-deterministic.
2/1 0.29152
3/1 0.23496
4/1 0.28316 0.25906 +/- 0.02410
5/1 0.33071 0.28294 +/- 0.02764
6/1 0.29656 0.28635 +/- 0.01984
7/1 0.33475 0.29603 +/- 0.01816
8/1 0.33741 0.30293 +/- 0.01636
9/1 0.32817 0.30653 +/- 0.01429
10/1 0.32218 0.30849 +/- 0.01252
11/1 0.32589 0.31042 +/- 0.01121
12/1 0.30819 0.31020 +/- 0.01003
13/1 0.34391 0.31326 +/- 0.00958
14/1 0.34969 0.31630 +/- 0.00926
15/1 0.31341 0.31608 +/- 0.00852
16/1 0.31948 0.31632 +/- 0.00789
17/1 0.29073 0.31461 +/- 0.00754
18/1 0.35823 0.31734 +/- 0.00756
19/1 0.34117 0.31874 +/- 0.00724
20/1 0.33679 0.31974 +/- 0.00690
21/1 0.34219 0.32093 +/- 0.00663
22/1 0.33271 0.32152 +/- 0.00632
23/1 0.30922 0.32093 +/- 0.00604
24/1 0.31494 0.32066 +/- 0.00576
25/1 0.33787 0.32141 +/- 0.00556
26/1 0.31956 0.32133 +/- 0.00532
27/1 0.32350 0.32142 +/- 0.00511
28/1 0.31837 0.32130 +/- 0.00491
29/1 0.34149 0.32205 +/- 0.00478
30/1 0.35485 0.32322 +/- 0.00475
31/1 0.30683 0.32265 +/- 0.00462
32/1 0.34797 0.32350 +/- 0.00454
33/1 0.33865 0.32399 +/- 0.00442
34/1 0.32677 0.32407 +/- 0.00428
35/1 0.34610 0.32474 +/- 0.00420
36/1 0.27797 0.32336 +/- 0.00430
37/1 0.34029 0.32385 +/- 0.00421
38/1 0.32603 0.32391 +/- 0.00409
39/1 0.31088 0.32356 +/- 0.00399
40/1 0.33812 0.32394 +/- 0.00390
41/1 0.31335 0.32367 +/- 0.00381
42/1 0.33263 0.32389 +/- 0.00372
43/1 0.32704 0.32397 +/- 0.00363
44/1 0.33763 0.32429 +/- 0.00356
45/1 0.31275 0.32403 +/- 0.00349
46/1 0.33732 0.32433 +/- 0.00342
47/1 0.34077 0.32469 +/- 0.00336
48/1 0.31724 0.32453 +/- 0.00329
49/1 0.35245 0.32513 +/- 0.00328
50/1 0.32012 0.32502 +/- 0.00321
51/1 0.33628 0.32525 +/- 0.00315
52/1 0.34286 0.32560 +/- 0.00311
53/1 0.35109 0.32610 +/- 0.00309
54/1 0.32581 0.32610 +/- 0.00303
55/1 0.34943 0.32654 +/- 0.00300
56/1 0.32672 0.32654 +/- 0.00295
57/1 0.34009 0.32679 +/- 0.00290
58/1 0.32261 0.32671 +/- 0.00285
59/1 0.35188 0.32715 +/- 0.00283
60/1 0.31951 0.32702 +/- 0.00279
61/1 0.30169 0.32659 +/- 0.00277
62/1 0.35895 0.32713 +/- 0.00278
63/1 0.29275 0.32657 +/- 0.00279
64/1 0.33903 0.32677 +/- 0.00275
65/1 0.32215 0.32670 +/- 0.00271
66/1 0.36862 0.32735 +/- 0.00275
67/1 0.32183 0.32727 +/- 0.00271
68/1 0.33903 0.32744 +/- 0.00267
69/1 0.32474 0.32740 +/- 0.00263
70/1 0.32970 0.32744 +/- 0.00259
71/1 0.34818 0.32774 +/- 0.00257
72/1 0.30736 0.32745 +/- 0.00255
73/1 0.34759 0.32773 +/- 0.00253
74/1 0.30709 0.32744 +/- 0.00251
75/1 0.35510 0.32782 +/- 0.00251
76/1 0.31558 0.32766 +/- 0.00248
77/1 0.32717 0.32765 +/- 0.00244
78/1 0.30746 0.32739 +/- 0.00243
79/1 0.33808 0.32752 +/- 0.00240
80/1 0.31947 0.32742 +/- 0.00237
81/1 0.31504 0.32726 +/- 0.00235
82/1 0.33674 0.32738 +/- 0.00232
83/1 0.32665 0.32737 +/- 0.00229
84/1 0.32946 0.32740 +/- 0.00226
85/1 0.35688 0.32775 +/- 0.00226
86/1 0.33045 0.32779 +/- 0.00224
87/1 0.31801 0.32767 +/- 0.00221
88/1 0.35223 0.32796 +/- 0.00221
89/1 0.32088 0.32788 +/- 0.00218
90/1 0.34545 0.32808 +/- 0.00217

How can I solve this? If you suggest me something, then I will be very grateful.

2

It’s hard to say for sure what’s going on here without seeing the DAGMC geometry, but that geometry representation is inherently 3D yet the rectangular_prism function returns a region that is 2D. I’d give the RectangularParallelpiped object a try instead.

class RectangularParallelepiped(CompositeSurface):

3

import openmc

from IPython.display import Image
from matplotlib import pyplot as plt

materials

u235 = openmc.Material(name=“fuel”)
u235.add_nuclide(‘U235’, 1.0, ‘ao’)
u235.set_density(‘g/cc’, 11)

water = openmc.Material(name=“water”)
water.add_nuclide(‘H1’, 2.0, ‘ao’)
water.add_nuclide(‘O16’, 1.0, ‘ao’)
water.set_density(‘g/cc’, 1.0)
water.add_s_alpha_beta(‘c_H_in_H2O’)
materials = openmc.Materials([u235,water])

dagmc_univ = openmc.DAGMCUniverse(filename=‘bal4.h5m’, auto_geom_ids=True, auto_mat_ids=True)
bounding_box = openmc.model.RectangularParallelepiped(-20,20,-20,20,-20,20,boundary_type=‘vacuum’)

cell = openmc.Cell(region=bounding_box, fill=dagmc_univ)
geometry = openmc.Geometry([cell])

settings = openmc.Settings()
settings.batches = 120
settings.inactive = 2
settings.particles = 1000

model = openmc.Model(geometry=geometry, materials=materials, settings=settings)
model.export_to_model_xml()

p = openmc.Plot()
p.width = (25.0, 25.0)
p.pixels = (400, 400)
p.color_by = ‘material’
p.colors = {u235: ‘yellow’, water:‘red’}
openmc.plot_inline(p)

Sorry I don’t know how should I apply RectangularParallelepiped function. When I applied, it shows some error like:

TypeError: Unable to set “cell region” to “<RectangularParallelepiped at 0x7f292cdcc160>” which is not of type “Region”

Can you suggest me something to solve it?

4

The RectangulaParallelPiped object is a little different in application than the region returned from rectangular_prism. In this case, a region is generated from the RectangulaParallelPiped using the - operator.

So cell = openmc.Cell(region=bounding_box, fill=dagmc_univ) should become cell = openmc.Cell(region=-bounding_box, fill=dagmc_univ)

5

Thank you Patrick, again you have taught me something new

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