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Merged
paulromano merged 15 commits into from
Oct 28, 2025
Merged

Criticality search method on the Model class #3569

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e23d476
Implement Model.keff_search method
paulromano Jul 31, 2025
9ab24db
Implement GRsecant algorithm
paulromano Aug 9, 2025
b7d4ef8
Determine number of generations based on r=0.5
paulromano Aug 11, 2025
d48358e
Add one more TODO
paulromano Aug 11, 2025
705b37d
Lots of updates to keff_search and grsecant
paulromano Sep 11, 2025
eec0f94
Inline grsecant in Model.keff_search
paulromano Sep 11, 2025
0072992
Add description of GRsecant in docstring
paulromano Sep 11, 2025
a9ea0aa
Rename print_iterations --> output
paulromano Sep 11, 2025
9dce3df
Add support for keff search with openmc.lib
paulromano Sep 15, 2025
36fccf7
Get rid of b1 argument
paulromano Sep 15, 2025
2a15eb8
Add documentation on stopping criterion
paulromano Sep 15, 2025
0d580ad
Fix two failing tests
paulromano Sep 17, 2025
d49af74
Merge branch 'develop' into model-keff-search
paulromano Oct 13, 2025
7948ba6
Incorporate suggestion from @church89
paulromano Oct 13, 2025
efcb773
Add test for keff_search method
paulromano Oct 13, 2025
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Add support for keff search with openmc.lib
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@paulromano
paulromano committed Sep 15, 2025
commit 9dce3dfcdc550ff16685a9bfe97eb52433e2c1fe
26 changes: 18 additions & 8 deletions openmc/model/model.py
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Original file line number Diff line number Diff line change
Expand Up @@ -2238,7 +2238,8 @@ def keff_search(
func_kwargs : dict, optional
Keyword-based arguments to pass to the `func` function.
run_kwargs : dict, optional
Keyword arguments to pass to :meth:`openmc.Model.run`.
Keyword arguments to pass to :meth:`openmc.Model.run` or
:meth:`openmc.lib.run`.

Returns
-------
Expand All @@ -2248,6 +2249,7 @@ def keff_search(
batches), plus convergence status and termination reason.

"""
import openmc.lib

check_type('model modifier', func, Callable)
check_type('target', target, Real)
Expand All @@ -2270,18 +2272,25 @@ def eval_at(x: float, batches: int) -> tuple[float, float]:
# Modify the model with the current guess
func(x, **func_kwargs)

# Change the number of batches
self.settings.batches = self.settings.inactive + batches
# Change the number of batches and run the model
batches = self.settings.inactive + batches
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if openmc.lib.is_initialized:
openmc.lib.settings.set_batches(batches)
openmc.lib.reset()
openmc.lib.run(**run_kwargs)
sp_filepath = f'statepoint.{batches}.h5'
else:
self.settings.batches = batches
sp_filepath = self.run(**run_kwargs)

# Run the model and obtain keff
sp_filepath = self.run(**run_kwargs)
# Extract keff and its uncertainty
with openmc.StatePoint(sp_filepath) as sp:
keff = sp.keff

if output:
nonlocal count
count += 1
print(f'Iteration {count}: {batches=}, {x=:.2e}, {keff=:.5f}')
print(f'Iteration {count}: {batches=}, {x=:.6g}, {keff=:.5f}')

xs.append(float(x))
fs.append(float(keff.n - target))
Expand All @@ -2297,7 +2306,8 @@ def eval_at(x: float, batches: int) -> tuple[float, float]:

# Perform the search (inlined GRsecant) in a temporary directory
with TemporaryDirectory() as tmpdir:
run_kwargs.setdefault('cwd', tmpdir)
if not openmc.lib.is_initialized:
run_kwargs.setdefault('cwd', tmpdir)

# ---- Seed with two evaluations
f0, s0 = eval_at(x0, b0)
Expand All @@ -2307,7 +2317,7 @@ def eval_at(x: float, batches: int) -> tuple[float, float]:
if abs(f1) <= k_tol and s1 <= sigma_final:
return SearchResult(x1, xs, fs, ss, gs, True, "converged")

for _ in range(maxiter):
for _ in range(maxiter - 2):
# ------ Step 1: propose next x via GRsecant
m = min(memory, len(xs))

Expand Down
5 changes: 0 additions & 5 deletions src/settings.cpp
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Expand Up @@ -1210,11 +1210,6 @@ extern "C" int openmc_set_n_batches(
return OPENMC_E_INVALID_ARGUMENT;
}

if (simulation::current_batch >= n_batches) {
set_errmsg("Number of batches must be greater than current batch.");
return OPENMC_E_INVALID_ARGUMENT;
}

if (!settings::trigger_on) {
// Set n_batches and n_max_batches to same value
settings::n_batches = n_batches;
Expand Down