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Allow zero bins in tally triggers (#2928)
Co-authored-by: Paul Romano <paul.k.romano@gmail.com>
1 parent d1366c0 commit c976653

6 files changed

Lines changed: 90 additions & 7 deletions

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‎docs/source/io_formats/tallies.rst‎

Lines changed: 12 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -100,6 +100,18 @@ The ``<tally>`` element accepts the following sub-elements:
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*Default*: None
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103+
:ignore_zeros:
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Whether to allow zero tally bins to be ignored when assessing the
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convergece of the precision trigger. If True, only nonzero tally scores
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will be compared to the trigger's threshold.
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.. note:: The ``ignore_zeros`` option can cause the tally trigger to fire
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prematurely if there are no hits in any bins at the first
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evalulation. It is the user's responsibility to specify enough
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particles per batch to get a nonzero score in at least one bin.
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*Default*: False
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:scores:
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The score(s) in this tally to which the trigger should be applied.
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‎include/openmc/tallies/trigger.h‎

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Original file line numberDiff line numberDiff line change
@@ -23,6 +23,7 @@ enum class TriggerMetric {
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struct Trigger {
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TriggerMetric metric; //!< The type of uncertainty (e.g. std dev) measured
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double threshold; //!< Uncertainty value below which trigger is satisfied
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bool ignore_zeros; //!< Whether to allow zero tally bins to be ignored
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int score_index; //!< Index of the relevant score in the tally's arrays
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};
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‎openmc/trigger.py‎

Lines changed: 26 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -17,6 +17,12 @@ class Trigger(EqualityMixin):
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relative error of scores.
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threshold : float
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The threshold for the trigger type.
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ignore_zeros : bool
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Whether to allow zero tally bins to be ignored. Note that this option
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can cause the trigger to fire prematurely if there are zero scores in
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any bin at the first evaluation.
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.. versionadded:: 0.14.1
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Attributes
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----------
@@ -27,18 +33,22 @@ class Trigger(EqualityMixin):
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The threshold for the trigger type.
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scores : list of str
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Scores which should be checked against the trigger
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ignore_zeros : bool
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Whether to allow zero tally bins to be ignored.
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"""
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33-
def __init__(self, trigger_type: str, threshold: float):
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def __init__(self, trigger_type: str, threshold: float, ignore_zeros: bool = False):
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self.trigger_type = trigger_type
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self.threshold = threshold
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self.ignore_zeros = ignore_zeros
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self._scores = []
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def __repr__(self):
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string = 'Trigger\n'
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string += '{: <16}=\t{}\n'.format('\tType', self._trigger_type)
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string += '{: <16}=\t{}\n'.format('\tThreshold', self._threshold)
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string += '{: <16}=\t{}\n'.format('\tIgnore Zeros', self._ignore_zeros)
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string += '{: <16}=\t{}\n'.format('\tScores', self._scores)
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return string
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@@ -61,6 +71,15 @@ def threshold(self, threshold):
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cv.check_type('tally trigger threshold', threshold, Real)
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self._threshold = threshold
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@property
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def ignore_zeros(self):
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return self._ignore_zeros
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@ignore_zeros.setter
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def ignore_zeros(self, ignore_zeros):
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cv.check_type('tally trigger ignores zeros', ignore_zeros, bool)
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self._ignore_zeros = ignore_zeros
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@property
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def scores(self):
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return self._scores
@@ -88,6 +107,8 @@ def to_xml_element(self):
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element = ET.Element("trigger")
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element.set("type", self._trigger_type)
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element.set("threshold", str(self._threshold))
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if self._ignore_zeros:
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element.set("ignore_zeros", "true")
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if len(self._scores) != 0:
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element.set("scores", ' '.join(self._scores))
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return element
@@ -110,7 +131,10 @@ def from_xml_element(cls, elem: ET.Element):
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# Generate trigger object
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trigger_type = elem.get("type")
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threshold = float(elem.get("threshold"))
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trigger = cls(trigger_type, threshold)
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ignore_zeros = str(elem.get("ignore_zeros", "false")).lower()
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# Try to convert to bool. Let Trigger error out on instantiation.
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ignore_zeros = ignore_zeros in ('true', '1')
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trigger = cls(trigger_type, threshold, ignore_zeros)
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# Add scores if present
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scores = elem.get("scores")

‎src/tallies/tally.cpp‎

Lines changed: 8 additions & 2 deletions
Original file line numberDiff line numberDiff line change
@@ -690,6 +690,12 @@ void Tally::init_triggers(pugi::xml_node node)
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"Must specify trigger threshold for tally {} in tally XML file", id_));
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}
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// Read whether to allow zero-tally bins to be ignored.
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bool ignore_zeros = false;
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if (check_for_node(trigger_node, "ignore_zeros")) {
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ignore_zeros = get_node_value_bool(trigger_node, "ignore_zeros");
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}
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// Read the trigger scores.
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vector<std::string> trigger_scores;
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if (check_for_node(trigger_node, "scores")) {
@@ -703,7 +709,7 @@ void Tally::init_triggers(pugi::xml_node node)
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if (score_str == "all") {
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triggers_.reserve(triggers_.size() + this->scores_.size());
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for (auto i_score = 0; i_score < this->scores_.size(); ++i_score) {
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triggers_.push_back({metric, threshold, i_score});
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triggers_.push_back({metric, threshold, ignore_zeros, i_score});
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}
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} else {
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int i_score = 0;
@@ -717,7 +723,7 @@ void Tally::init_triggers(pugi::xml_node node)
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"{} but it was listed in a trigger on that tally",
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score_str, id_));
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}
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triggers_.push_back({metric, threshold, i_score});
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triggers_.push_back({metric, threshold, ignore_zeros, i_score});
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}
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}
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}

‎src/tallies/trigger.cpp‎

Lines changed: 3 additions & 3 deletions
Original file line numberDiff line numberDiff line change
@@ -77,9 +77,9 @@ void check_tally_triggers(double& ratio, int& tally_id, int& score)
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auto uncert_pair =
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get_tally_uncertainty(i_tally, trigger.score_index, filter_index);
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80-
// if there is a score without contributions, set ratio to inf and
81-
// exit early
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if (uncert_pair.first == -1) {
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// If there is a score without contributions, set ratio to inf and
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// exit early, unless zero scores are ignored for this trigger.
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if (uncert_pair.first == -1 && !trigger.ignore_zeros) {
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ratio = INFINITY;
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score = t.scores_[trigger.score_index];
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tally_id = t.id_;

‎tests/unit_tests/test_triggers.py‎

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Original file line numberDiff line numberDiff line change
@@ -73,3 +73,43 @@ def test_tally_trigger_null_score(run_in_tmpdir):
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total_batches = sp.n_realizations + sp.n_inactive
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assert total_batches == pincell.settings.trigger_max_batches
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def test_tally_trigger_zero_ignored(run_in_tmpdir):
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pincell = openmc.examples.pwr_pin_cell()
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# create an energy filter below and around the O-16(n,p) threshold (1.02e7 eV)
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e_filter = openmc.EnergyFilter([0.0, 1e7, 2e7])
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# create a tally with triggers applied
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tally = openmc.Tally()
85+
tally.filters = [e_filter]
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tally.scores = ['(n,p)']
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tally.nuclides = ["O16"]
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89+
# 100% relative error: should be immediately satisfied in nonzero bin
90+
trigger = openmc.Trigger('rel_err', 1.0)
91+
trigger.scores = ['(n,p)']
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trigger.ignore_zeros = True
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tally.triggers = [trigger]
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pincell.tallies = [tally]
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pincell.settings.particles = 1000 # we need a few more particles for this
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pincell.settings.trigger_active = True
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pincell.settings.trigger_max_batches = 50
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pincell.settings.trigger_batch_interval = 20
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sp_file = pincell.run()
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with openmc.StatePoint(sp_file) as sp:
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# verify that the first bin is zero and the second is nonzero
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tally_out = sp.get_tally(id=tally.id)
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below, above = tally_out.mean.squeeze()
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assert below == 0.0, "Tally events observed below expected threshold"
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assert above > 0, "No tally events observed. Test with more particles."
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# we expect that the trigger fires before max batches are hit
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total_batches = sp.n_realizations + sp.n_inactive
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assert total_batches < pincell.settings.trigger_max_batches
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