Skip to content

CRAM clip negative atoms #3879

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
yrrepy wants to merge 3 commits into
base: develop
Choose a base branch
from
+28 −1
Open

CRAM clip negative atoms #3879

Changes from all commits
Commits
Show all changes
3 commits
Select commit Hold shift + click to select a range
52b4963
Clip negative atom densities after CRAM solves
yrrepy Feb 12, 2026
c9f45cb
● Add opt-in clipping of negative atom densities after CRAM solve
yrrepy Mar 13, 2026
23746f1
Remove Test
yrrepy Mar 14, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
29 changes: 28 additions & 1 deletion openmc/deplete/abc.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -583,6 +583,11 @@ class Integrator(ABC):
`source_rates` should be the same as the initial run.

.. versionadded:: 0.15.1
clip_negative_densities : bool, optional
Whether to clip negative atom densities to zero after each CRAM
solve. CRAM can produce small negative values. Defaults to False.

.. versionadded:: 0.15.4

Attributes
----------
Expand Down Expand Up @@ -632,6 +637,7 @@ def __init__(
timestep_units: str = 's',
solver: str = "cram48",
continue_timesteps: bool = False,
clip_negative_densities: bool = False,
):
if continue_timesteps and operator.prev_res is None:
raise ValueError("Continuation run requires passing prev_results.")
Expand Down Expand Up @@ -684,6 +690,8 @@ def __init__(
self.timesteps = np.asarray(seconds)
self.source_rates = np.asarray(source_rates)

self.clip_negative_densities = clip_negative_densities
self._warned_negative_density = False
self.transfer_rates = None
self.external_source_rates = None

Expand Down Expand Up @@ -736,6 +744,17 @@ def _timed_deplete(self, n, rates, dt, i=None, matrix_func=None):
results = deplete(
self._solver, self.chain, n, rates, dt, i, matrix_func,
self.transfer_rates, self.external_source_rates)
if self.clip_negative_densities:
for j, r in enumerate(results):
neg_mask = r < 0
if neg_mask.any():
if not self._warned_negative_density:
idx = np.argmin(r)
nuc = self.chain.nuclides[idx].name
warn(f"Clipping negative atom densities "
f"(worst: {nuc} = {r[idx]:.4e})")
self._warned_negative_density = True
results[j] = np.maximum(r, 0.0)
return time.time() - start, results

@abstractmethod
Expand Down Expand Up @@ -1116,6 +1135,11 @@ class SIIntegrator(Integrator):
`source_rates` should be the same as the initial run.

.. versionadded:: 0.15.1
clip_negative_densities : bool, optional
Whether to clip negative atom densities to zero after each CRAM
solve. CRAM can produce small negative values. Defaults to False.

.. versionadded:: 0.15.4

Attributes
----------
Expand Down Expand Up @@ -1159,12 +1183,15 @@ def __init__(
n_steps: int = 10,
solver: str = "cram48",
continue_timesteps: bool = False,
clip_negative_densities: bool = False,
):
check_type("n_steps", n_steps, Integral)
check_greater_than("n_steps", n_steps, 0)
super().__init__(
operator, timesteps, power, power_density, source_rates,
timestep_units=timestep_units, solver=solver, continue_timesteps=continue_timesteps)
timestep_units=timestep_units, solver=solver,
continue_timesteps=continue_timesteps,
clip_negative_densities=clip_negative_densities)
self.n_steps = n_steps

def _get_bos_data_from_operator(self, step_index, step_power, n_bos):
Expand Down
Loading