23460042813

Committed 23 Mar 2026 09:04PM UTC coverage: 81.334% (-0.2%) from 81.556%

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Pull #3832

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Merge 1144e8851 into 6cd39073b

Pull Request Pull Request #3832: Allowing multiple cells in surface source banking

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75.66

/src/secondary_thermal.cpp

#include "openmc/secondary_thermal.h"

#include "openmc/hdf5_interface.h"
#include "openmc/math_functions.h"
#include "openmc/random_lcg.h"
#include "openmc/search.h"
#include "openmc/vector.h"

#include "openmc/tensor.h"

#include <cassert>
#include <cmath> // for log, exp

namespace openmc {

//==============================================================================
// CoherentElasticAE implementation
//==============================================================================

CoherentElasticAE::CoherentElasticAE(const CoherentElasticXS& xs) : xs_ {xs}
{
  const auto& bragg = xs_.bragg_edges();
  auto n = bragg.size();
  bragg_edges_ = tensor::Tensor<double>(bragg.data(), n);

  const auto& factors = xs_.factors();
  factors_diff_ = tensor::zeros<double>({n});
  factors_diff_.slice(0) = factors[0];
  for (int i = 1; i < n; ++i) {
    factors_diff_.slice(i) = factors[i] - factors[i - 1];
  }
}

void CoherentElasticAE::sample(
  double E_in, double& E_out, double& mu, uint64_t* seed) const
{
  // Energy doesn't change in elastic scattering (ENDF-102, Eq. 7-1)
  E_out = E_in;
  const auto& energies {xs_.bragg_edges()};
  assert(E_in >= energies.front());

  const int i = lower_bound_index(energies.begin(), energies.end(), E_in);

  // Sample a Bragg edge between 1 and i
  // E[0] < E_in < E[i+1] -> can scatter in bragg edges 0..i
  const auto& factors = xs_.factors();
  const double prob = prn(seed) * factors[i];

  const int k = std::lower_bound(factors.begin(), factors.begin() + i, prob) -
                factors.begin();

  // Characteristic scattering cosine for this Bragg edge (ENDF-102, Eq. 7-2)
  mu = 1.0 - 2.0 * energies[k] / E_in;
}

double CoherentElasticAE::sample_energy_and_pdf(
  double E_in, double mu, double& E_out, uint64_t* seed) const
{
  // Energy doesn't change in elastic scattering (ENDF-102, Eq. 7-1)
  E_out = E_in;
  const auto& factors = xs_.factors();

  if (E_in < bragg_edges_.front())
    return 0.0;

  const int i =
    lower_bound_index(bragg_edges_.begin(), bragg_edges_.end(), E_in);
  double E = 0.5 * (1 - mu) * E_in;
  double C = 0.5 * E_in / factors[i];

  return C * get_pdf_discrete(bragg_edges_.slice(tensor::range(i + 1)),
               factors_diff_.slice(tensor::range(i + 1)), E, 0.0, E_in);
}

//==============================================================================
// IncoherentElasticAE implementation
//==============================================================================

IncoherentElasticAE::IncoherentElasticAE(hid_t group)
{
  read_dataset(group, "debye_waller", debye_waller_);
}

void IncoherentElasticAE::sample(
  double E_in, double& E_out, double& mu, uint64_t* seed) const
{
  E_out = E_in;

  // Sample angle by inverting the distribution in ENDF-102, Eq. 7.4
  double c = 2 * E_in * debye_waller_;
  mu = std::log(1.0 + prn(seed) * (std::exp(2.0 * c) - 1)) / c - 1.0;
}
double IncoherentElasticAE::sample_energy_and_pdf(
  double E_in, double mu, double& E_out, uint64_t* seed) const
{
  E_out = E_in;

  // Sample angle by inverting the distribution in ENDF-102, Eq. 7.4
  double c = 2 * E_in * debye_waller_;
  double A = c / (1 - std::exp(-2.0 * c)); // normalization factor
  return A * std::exp(-c * (1 - mu));
}

//==============================================================================
// IncoherentElasticAEDiscrete implementation
//==============================================================================

IncoherentElasticAEDiscrete::IncoherentElasticAEDiscrete(
  hid_t group, const vector<double>& energy)
  : energy_ {energy}
{
  read_dataset(group, "mu_out", mu_out_);
}

void IncoherentElasticAEDiscrete::sample(
  double E_in, double& E_out, double& mu, uint64_t* seed) const
{
  // Get index and interpolation factor for elastic grid
  int i;
  double f;
  get_energy_index(energy_, E_in, i, f);

  // Interpolate between two discrete cosines corresponding to neighboring
  // incoming energies.

  // Sample outgoing cosine bin
  int n_mu = mu_out_.shape(1);
  int k = prn(seed) * n_mu;

  // Rather than use the sampled discrete mu directly, it is smeared over
  // a bin of width 0.5*min(mu[k] - mu[k-1], mu[k+1] - mu[k]) centered on the
  // discrete mu value itself.

  // Interpolate kth mu value between distributions at energies i and i+1
  mu = mu_out_(i, k) + f * (mu_out_(i + 1, k) - mu_out_(i, k));

  // Inteprolate (k-1)th mu value between distributions at energies i and i+1.
  // When k==0, pick a value that will smear the cosine out to a minimum of -1.
  double mu_left = (k == 0) ? -1.0 - (mu + 1.0)
                            : mu_out_(i, k - 1) +
                                f * (mu_out_(i + 1, k - 1) - mu_out_(i, k - 1));

  // Inteprolate (k+1)th mu value between distributions at energies i and i+1.
  // When k is the last discrete value, pick a value that will smear the cosine
  // out to a maximum of 1.
  double mu_right =
    (k == n_mu - 1)
      ? 1.0 + (1.0 - mu)
      : mu_out_(i, k + 1) + f * (mu_out_(i + 1, k + 1) - mu_out_(i, k + 1));

  // Smear cosine
  mu += std::min(mu - mu_left, mu_right - mu) * (prn(seed) - 0.5);

  // Energy doesn't change in elastic scattering
  E_out = E_in;
}

double IncoherentElasticAEDiscrete::sample_energy_and_pdf(
  double E_in, double mu, double& E_out, uint64_t* seed) const
{
  // Get index and interpolation factor for elastic grid
  int i;
  double f;
  get_energy_index(energy_, E_in, i, f);
  // Energy doesn't change in elastic scattering
  E_out = E_in;

  return get_pdf_discrete_interpolated(
    mu_out_.slice(i, tensor::all), mu_out_.slice(i + 1, tensor::all), f, mu);
}

//==============================================================================
// IncoherentInelasticAEDiscrete implementation
//==============================================================================

IncoherentInelasticAEDiscrete::IncoherentInelasticAEDiscrete(
  hid_t group, const vector<double>& energy)
  : energy_ {energy}
{
  read_dataset(group, "energy_out", energy_out_);
  read_dataset(group, "mu_out", mu_out_);
  read_dataset(group, "skewed", skewed_);
}

void IncoherentInelasticAEDiscrete::sample_params(
  double E_in, double& E_out, int& j, uint64_t* seed) const
{
  // Get index and interpolation factor for inelastic grid
  int i;
  double f;
  get_energy_index(energy_, E_in, i, f);

  // Now that we have an incoming energy bin, we need to determine the outgoing
  // energy bin. This will depend on whether the outgoing energy distribution is
  // skewed. If it is skewed, then the first two and last two bins have lower
  // probabilities than the other bins (0.1 for the first and last bins and 0.4
  // for the second and second to last bins, relative to a normal bin
  // probability of 1). Otherwise, each bin is equally probable.

  int n = energy_out_.shape(1);
  if (!skewed_) {
    // All bins equally likely
    j = prn(seed) * n;
  } else {
    // Distribution skewed away from edge points
    double r = prn(seed) * (n - 3);
    if (r > 1.0) {
      // equally likely N-4 middle bins
      j = r + 1;
    } else if (r > 0.6) {
      // second to last bin has relative probability of 0.4
      j = n - 2;
    } else if (r > 0.5) {
      // last bin has relative probability of 0.1
      j = n - 1;
    } else if (r > 0.1) {
      // second bin has relative probability of 0.4
      j = 1;
    } else {
      // first bin has relative probability of 0.1
      j = 0;
    }
  }

  // Determine outgoing energy corresponding to E_in[i] and E_in[i+1]
  double E_ij = energy_out_(i, j);
  double E_i1j = energy_out_(i + 1, j);

  // Outgoing energy
  E_out = (1 - f) * E_ij + f * E_i1j;
}

void IncoherentInelasticAEDiscrete::sample(
  double E_in, double& E_out, double& mu, uint64_t* seed) const
{
  // Get index and interpolation factor for inelastic grid
  int i;
  double f;
  get_energy_index(energy_, E_in, i, f);

  int j;
  sample_params(E_in, E_out, j, seed);

  // Sample outgoing cosine bin
  int m = mu_out_.shape(2);
  int k = prn(seed) * m;

  // Determine outgoing cosine corresponding to E_in[i] and E_in[i+1]
  double mu_ijk = mu_out_(i, j, k);
  double mu_i1jk = mu_out_(i + 1, j, k);

  // Cosine of angle between incoming and outgoing neutron
  mu = (1 - f) * mu_ijk + f * mu_i1jk;
}

double IncoherentInelasticAEDiscrete::sample_energy_and_pdf(
  double E_in, double mu, double& E_out, uint64_t* seed) const
{
  // Get index and interpolation factor for inelastic grid
  int i;
  double f;
  get_energy_index(energy_, E_in, i, f);
  int j;
  sample_params(E_in, E_out, j, seed);

  return get_pdf_discrete_interpolated(mu_out_.slice(i, j, tensor::all),
    mu_out_.slice(i + 1, j, tensor::all), f, mu);
}

//==============================================================================
// IncoherentInelasticAE implementation
//==============================================================================

IncoherentInelasticAE::IncoherentInelasticAE(hid_t group)
{
  // Read correlated angle-energy distribution
  CorrelatedAngleEnergy dist {group};

  // Copy incident energies
  energy_ = dist.energy();

  // Convert to S(a,b) native format
  for (const auto& edist : dist.distribution()) {
    // Create temporary distribution
    DistEnergySab d;

    // Copy outgoing energy distribution
    d.n_e_out = edist.e_out.size();
    d.e_out = edist.e_out;
    d.e_out_pdf = edist.p;
    d.e_out_cdf = edist.c;

    for (int j = 0; j < d.n_e_out; ++j) {
      auto adist = dynamic_cast<Tabular*>(edist.angle[j].get());
      if (adist) {
        // On first pass, allocate space for angles
        if (j == 0) {
          auto n_mu = adist->x().size();
          d.mu = tensor::Tensor<double>({d.n_e_out, n_mu});
        }

        // Copy outgoing angles
        tensor::View<double> mu_j = d.mu.slice(j);
        std::copy(adist->x().begin(), adist->x().end(), mu_j.begin());
      }
    }

    distribution_.emplace_back(std::move(d));
  }
}

void IncoherentInelasticAE::sample_params(
  double E_in, double& E_out, double& f, int& l, int& j, uint64_t* seed) const
{
  // Get index and interpolation factor for inelastic grid
  int i;
  double f0;
  get_energy_index(energy_, E_in, i, f0);

  // Pick closer energy based on interpolation factor
  l = f0 > 0.5 ? i + 1 : i;

  // Determine outgoing energy bin
  // (First reset n_energy_out to the right value)
  int n = distribution_[l].n_e_out;
  double r1 = prn(seed);
  double c_j = distribution_[l].e_out_cdf[0];
  double c_j1;
  for (j = 0; j < n - 1; ++j) {
    c_j1 = distribution_[l].e_out_cdf[j + 1];
    if (r1 < c_j1)
      break;
    c_j = c_j1;
  }

  // check to make sure j is <= n_energy_out - 2
  j = std::min(j, n - 2);

  // Get the data to interpolate between
  double E_l_j = distribution_[l].e_out[j];
  double p_l_j = distribution_[l].e_out_pdf[j];

  // Next part assumes linear-linear interpolation in standard
  double E_l_j1 = distribution_[l].e_out[j + 1];
  double p_l_j1 = distribution_[l].e_out_pdf[j + 1];

  // Find secondary energy (variable E)
  double frac = (p_l_j1 - p_l_j) / (E_l_j1 - E_l_j);
  if (frac == 0.0) {
    E_out = E_l_j + (r1 - c_j) / p_l_j;
  } else {
    E_out = E_l_j +
            (std::sqrt(std::max(0.0, p_l_j * p_l_j + 2.0 * frac * (r1 - c_j))) -
              p_l_j) /
              frac;
  }

  // Adjustment of outgoing energy
  double E_l = energy_[l];
  if (E_out < 0.5 * E_l) {
    E_out *= 2.0 * E_in / E_l - 1.0;
  } else {
    E_out += E_in - E_l;
  }

  f = (r1 - c_j) / (c_j1 - c_j);
}
void IncoherentInelasticAE::sample(
  double E_in, double& E_out, double& mu, uint64_t* seed) const
{
  double f;
  int l, j;
  sample_params(E_in, E_out, f, l, j, seed);

  // Sample outgoing cosine bin
  int n_mu = distribution_[l].mu.shape(1);
  std::size_t k = prn(seed) * n_mu;

  // Rather than use the sampled discrete mu directly, it is smeared over
  // a bin of width 0.5*min(mu[k] - mu[k-1], mu[k+1] - mu[k]) centered on the
  // discrete mu value itself.
  const auto& mu_l = distribution_[l].mu;

  // Interpolate kth mu value between distributions at energies j and j+1
  mu = mu_l(j, k) + f * (mu_l(j + 1, k) - mu_l(j, k));

  // Inteprolate (k-1)th mu value between distributions at energies j and j+1.
  // When k==0, pick a value that will smear the cosine out to a minimum of -1.
  double mu_left =
    (k == 0)
      ? mu_left = -1.0 - (mu + 1.0)
      : mu_left = mu_l(j, k - 1) + f * (mu_l(j + 1, k - 1) - mu_l(j, k - 1));

  // Inteprolate (k+1)th mu value between distributions at energies j and j+1.
  // When k is the last discrete value, pick a value that will smear the cosine
  // out to a maximum of 1.
  double mu_right =
    (k == n_mu - 1)
      ? mu_right = 1.0 + (1.0 - mu)
      : mu_right = mu_l(j, k + 1) + f * (mu_l(j + 1, k + 1) - mu_l(j, k + 1));

  // Smear cosine
  mu += std::min(mu - mu_left, mu_right - mu) * (prn(seed) - 0.5);
}

double IncoherentInelasticAE::sample_energy_and_pdf(
  double E_in, double mu, double& E_out, uint64_t* seed) const
{
  double f;
  int l, j;
  sample_params(E_in, E_out, f, l, j, seed);

  const auto& mu_l = distribution_[l].mu;

  return get_pdf_discrete_interpolated(
    mu_l.slice(j, tensor::all), mu_l.slice(j + 1, tensor::all), f, mu);
}

//==============================================================================
// MixedElasticAE implementation
//==============================================================================

MixedElasticAE::MixedElasticAE(
  hid_t group, const CoherentElasticXS& coh_xs, const Function1D& incoh_xs)
  : coherent_dist_(coh_xs), coherent_xs_(coh_xs), incoherent_xs_(incoh_xs)
{
  // Read incoherent elastic distribution
  hid_t incoherent_group = open_group(group, "incoherent");
  std::string temp;
  read_attribute(incoherent_group, "type", temp);
  if (temp == "incoherent_elastic") {
    incoherent_dist_ = make_unique<IncoherentElasticAE>(incoherent_group);
  } else if (temp == "incoherent_elastic_discrete") {
    auto xs = dynamic_cast<const Tabulated1D*>(&incoh_xs);
    incoherent_dist_ =
      make_unique<IncoherentElasticAEDiscrete>(incoherent_group, xs->x());
  }
  close_group(incoherent_group);
}

const AngleEnergy& MixedElasticAE::sample_dist(
  double E_in, uint64_t* seed) const
{
  // Evaluate coherent and incoherent elastic cross sections
  double xs_coh = coherent_xs_(E_in);
  double xs_incoh = incoherent_xs_(E_in);

  if (prn(seed) * (xs_coh + xs_incoh) < xs_coh) {
    return coherent_dist_;
  } else {
    return *incoherent_dist_;
  }
}

void MixedElasticAE::sample(
  double E_in, double& E_out, double& mu, uint64_t* seed) const
{
  sample_dist(E_in, seed).sample(E_in, E_out, mu, seed);
}

double MixedElasticAE::sample_energy_and_pdf(
  double E_in, double mu, double& E_out, uint64_t* seed) const
{
  return sample_dist(E_in, seed).sample_energy_and_pdf(E_in, mu, E_out, seed);
}

} // namespace openmc

1	#include "openmc/secondary_thermal.h"
2
3	#include "openmc/hdf5_interface.h"
4	#include "openmc/math_functions.h"
5	#include "openmc/random_lcg.h"
6	#include "openmc/search.h"
7	#include "openmc/vector.h"
8
9	#include "openmc/tensor.h"
10
11	#include <cassert>
12	#include <cmath> // for log, exp
13
14	namespace openmc {
15
16	//==============================================================================
17	// CoherentElasticAE implementation
18	//==============================================================================
19
20	CoherentElasticAE::CoherentElasticAE(const CoherentElasticXS& xs) : xs_ {xs}	134✔
21	{
22	const auto& bragg = xs_.bragg_edges();	134✔
23	auto n = bragg.size();	134✔
24	bragg_edges_ = tensor::Tensor<double>(bragg.data(), n);	134✔
25
26	const auto& factors = xs_.factors();	134✔
27	factors_diff_ = tensor::zeros<double>({n});	134✔
28	factors_diff_.slice(0) = factors[0];	134✔
29	for (int i = 1; i < n; ++i) {	19,878✔
30	factors_diff_.slice(i) = factors[i] - factors[i - 1];	39,488✔
31	}
32	}	134✔
33
34	void CoherentElasticAE::sample(	178,013✔
35	double E_in, double& E_out, double& mu, uint64_t* seed) const
36	{
37	// Energy doesn't change in elastic scattering (ENDF-102, Eq. 7-1)
38	E_out = E_in;	178,013✔
39	const auto& energies {xs_.bragg_edges()};	178,013!
40	assert(E_in >= energies.front());	178,013!
41
42	const int i = lower_bound_index(energies.begin(), energies.end(), E_in);	178,013✔
43
44	// Sample a Bragg edge between 1 and i
45	// E[0] < E_in < E[i+1] -> can scatter in bragg edges 0..i
46	const auto& factors = xs_.factors();	178,013✔
47	const double prob = prn(seed) * factors[i];	178,013✔
48
49	const int k = std::lower_bound(factors.begin(), factors.begin() + i, prob) -	178,013✔
50	factors.begin();	178,013✔
51
52	// Characteristic scattering cosine for this Bragg edge (ENDF-102, Eq. 7-2)
53	mu = 1.0 - 2.0 * energies[k] / E_in;	178,013✔
54	}	178,013✔
55
UNCOV 56	double CoherentElasticAE::sample_energy_and_pdf(	×
57	double E_in, double mu, double& E_out, uint64_t* seed) const
58	{
59	// Energy doesn't change in elastic scattering (ENDF-102, Eq. 7-1)
UNCOV 60	E_out = E_in;	×
UNCOV 61	const auto& factors = xs_.factors();	×
62
63	if (E_in < bragg_edges_.front())	×
64	return 0.0;
65
UNCOV 66	const int i =	×
UNCOV 67	lower_bound_index(bragg_edges_.begin(), bragg_edges_.end(), E_in);	×
UNCOV 68	double E = 0.5 * (1 - mu) * E_in;	×
UNCOV 69	double C = 0.5 * E_in / factors[i];	×
70
UNCOV 71	return C * get_pdf_discrete(bragg_edges_.slice(tensor::range(i + 1)),	×
UNCOV 72	factors_diff_.slice(tensor::range(i + 1)), E, 0.0, E_in);	×
73	}
74
75	//==============================================================================
76	// IncoherentElasticAE implementation
77	//==============================================================================
78
UNCOV 79	IncoherentElasticAE::IncoherentElasticAE(hid_t group)	×
80	{
UNCOV 81	read_dataset(group, "debye_waller", debye_waller_);	×
UNCOV 82	}	×
83
UNCOV 84	void IncoherentElasticAE::sample(	×
85	double E_in, double& E_out, double& mu, uint64_t* seed) const
86	{
UNCOV 87	E_out = E_in;	×
88
89	// Sample angle by inverting the distribution in ENDF-102, Eq. 7.4
UNCOV 90	double c = 2 * E_in * debye_waller_;	×
UNCOV 91	mu = std::log(1.0 + prn(seed) * (std::exp(2.0 * c) - 1)) / c - 1.0;	×
UNCOV 92	}	×
UNCOV 93	double IncoherentElasticAE::sample_energy_and_pdf(	×
94	double E_in, double mu, double& E_out, uint64_t* seed) const
95	{
UNCOV 96	E_out = E_in;	×
97
98	// Sample angle by inverting the distribution in ENDF-102, Eq. 7.4
UNCOV 99	double c = 2 * E_in * debye_waller_;	×
UNCOV 100	double A = c / (1 - std::exp(-2.0 * c)); // normalization factor	×
UNCOV 101	return A * std::exp(-c * (1 - mu));	×
102	}
103
104	//==============================================================================
105	// IncoherentElasticAEDiscrete implementation
106	//==============================================================================
107
108	IncoherentElasticAEDiscrete::IncoherentElasticAEDiscrete(	44✔
109	hid_t group, const vector<double>& energy)	44✔
110	: energy_ {energy}	44✔
111	{
112	read_dataset(group, "mu_out", mu_out_);	44✔
113	}	44✔
114
115	void IncoherentElasticAEDiscrete::sample(	1,342✔
116	double E_in, double& E_out, double& mu, uint64_t* seed) const
117	{
118	// Get index and interpolation factor for elastic grid
119	int i;	1,342✔
120	double f;	1,342✔
121	get_energy_index(energy_, E_in, i, f);	1,342✔
122
123	// Interpolate between two discrete cosines corresponding to neighboring
124	// incoming energies.
125
126	// Sample outgoing cosine bin
127	int n_mu = mu_out_.shape(1);	1,342!
128	int k = prn(seed) * n_mu;	1,342✔
129
130	// Rather than use the sampled discrete mu directly, it is smeared over
131	// a bin of width 0.5*min(mu[k] - mu[k-1], mu[k+1] - mu[k]) centered on the
132	// discrete mu value itself.
133
134	// Interpolate kth mu value between distributions at energies i and i+1
135	mu = mu_out_(i, k) + f * (mu_out_(i + 1, k) - mu_out_(i, k));	1,342✔
136
137	// Inteprolate (k-1)th mu value between distributions at energies i and i+1.
138	// When k==0, pick a value that will smear the cosine out to a minimum of -1.
139	double mu_left = (k == 0) ? -1.0 - (mu + 1.0)	1,342✔
140	: mu_out_(i, k - 1) +	990✔
141	f * (mu_out_(i + 1, k - 1) - mu_out_(i, k - 1));	990✔
142
143	// Inteprolate (k+1)th mu value between distributions at energies i and i+1.
144	// When k is the last discrete value, pick a value that will smear the cosine
145	// out to a maximum of 1.
146	double mu_right =	1,342✔
147	(k == n_mu - 1)	1,342✔
148	? 1.0 + (1.0 - mu)	1,342✔
149	: mu_out_(i, k + 1) + f * (mu_out_(i + 1, k + 1) - mu_out_(i, k + 1));	990✔
150
151	// Smear cosine
152	mu += std::min(mu - mu_left, mu_right - mu) * (prn(seed) - 0.5);	1,947✔
153
154	// Energy doesn't change in elastic scattering
155	E_out = E_in;	1,342✔
156	}	1,342✔
157
UNCOV 158	double IncoherentElasticAEDiscrete::sample_energy_and_pdf(	×
159	double E_in, double mu, double& E_out, uint64_t* seed) const
160	{
161	// Get index and interpolation factor for elastic grid
UNCOV 162	int i;	×
UNCOV 163	double f;	×
UNCOV 164	get_energy_index(energy_, E_in, i, f);	×
165	// Energy doesn't change in elastic scattering
UNCOV 166	E_out = E_in;	×
167
UNCOV 168	return get_pdf_discrete_interpolated(	×
UNCOV 169	mu_out_.slice(i, tensor::all), mu_out_.slice(i + 1, tensor::all), f, mu);	×
170	}
171
172	//==============================================================================
173	// IncoherentInelasticAEDiscrete implementation
174	//==============================================================================
175
176	IncoherentInelasticAEDiscrete::IncoherentInelasticAEDiscrete(	1,262✔
177	hid_t group, const vector<double>& energy)	1,262✔
178	: energy_ {energy}	1,262✔
179	{
180	read_dataset(group, "energy_out", energy_out_);	1,262✔
181	read_dataset(group, "mu_out", mu_out_);	1,262✔
182	read_dataset(group, "skewed", skewed_);	1,262✔
183	}	1,262✔
184
185	void IncoherentInelasticAEDiscrete::sample_params(	123,683,823✔
186	double E_in, double& E_out, int& j, uint64_t* seed) const
187	{
188	// Get index and interpolation factor for inelastic grid
189	int i;	123,683,823✔
190	double f;	123,683,823✔
191	get_energy_index(energy_, E_in, i, f);	123,683,823✔
192
193	// Now that we have an incoming energy bin, we need to determine the outgoing
194	// energy bin. This will depend on whether the outgoing energy distribution is
195	// skewed. If it is skewed, then the first two and last two bins have lower
196	// probabilities than the other bins (0.1 for the first and last bins and 0.4
197	// for the second and second to last bins, relative to a normal bin
198	// probability of 1). Otherwise, each bin is equally probable.
199
200	int n = energy_out_.shape(1);	123,683,823!
201	if (!skewed_) {	123,683,823!
202	// All bins equally likely
UNCOV 203	j = prn(seed) * n;	×
204	} else {
205	// Distribution skewed away from edge points
206	double r = prn(seed) * (n - 3);	123,683,823✔
207	if (r > 1.0) {	123,683,823✔
208	// equally likely N-4 middle bins
209	j = r + 1;	121,650,936✔
210	} else if (r > 0.6) {	2,032,887✔
211	// second to last bin has relative probability of 0.4
212	j = n - 2;	806,605✔
213	} else if (r > 0.5) {	1,226,282✔
214	// last bin has relative probability of 0.1
215	j = n - 1;	203,402✔
216	} else if (r > 0.1) {	1,022,880✔
217	// second bin has relative probability of 0.4
218	j = 1;	819,261✔
219	} else {
220	// first bin has relative probability of 0.1
221	j = 0;	203,619✔
222	}
223	}
224
225	// Determine outgoing energy corresponding to E_in[i] and E_in[i+1]
226	double E_ij = energy_out_(i, j);	123,683,823✔
227	double E_i1j = energy_out_(i + 1, j);	123,683,823✔
228
229	// Outgoing energy
230	E_out = (1 - f) * E_ij + f * E_i1j;	123,683,823✔
231	}	123,683,823✔
232
233	void IncoherentInelasticAEDiscrete::sample(	123,683,823✔
234	double E_in, double& E_out, double& mu, uint64_t* seed) const
235	{
236	// Get index and interpolation factor for inelastic grid
237	int i;	123,683,823✔
238	double f;	123,683,823✔
239	get_energy_index(energy_, E_in, i, f);	123,683,823✔
240
241	int j;	123,683,823✔
242	sample_params(E_in, E_out, j, seed);	123,683,823✔
243
244	// Sample outgoing cosine bin
245	int m = mu_out_.shape(2);	123,683,823!
246	int k = prn(seed) * m;	123,683,823✔
247
248	// Determine outgoing cosine corresponding to E_in[i] and E_in[i+1]
249	double mu_ijk = mu_out_(i, j, k);	123,683,823✔
250	double mu_i1jk = mu_out_(i + 1, j, k);	123,683,823✔
251
252	// Cosine of angle between incoming and outgoing neutron
253	mu = (1 - f) * mu_ijk + f * mu_i1jk;	123,683,823✔
254	}	123,683,823✔
255
UNCOV 256	double IncoherentInelasticAEDiscrete::sample_energy_and_pdf(	×
257	double E_in, double mu, double& E_out, uint64_t* seed) const
258	{
259	// Get index and interpolation factor for inelastic grid
UNCOV 260	int i;	×
UNCOV 261	double f;	×
UNCOV 262	get_energy_index(energy_, E_in, i, f);	×
UNCOV 263	int j;	×
UNCOV 264	sample_params(E_in, E_out, j, seed);	×
265
UNCOV 266	return get_pdf_discrete_interpolated(mu_out_.slice(i, j, tensor::all),	×
UNCOV 267	mu_out_.slice(i + 1, j, tensor::all), f, mu);	×
268	}
269
270	//==============================================================================
271	// IncoherentInelasticAE implementation
272	//==============================================================================
273
274	IncoherentInelasticAE::IncoherentInelasticAE(hid_t group)	44✔
275	{
276	// Read correlated angle-energy distribution
277	CorrelatedAngleEnergy dist {group};	44✔
278
279	// Copy incident energies
280	energy_ = dist.energy();	44✔
281
282	// Convert to S(a,b) native format
283	for (const auto& edist : dist.distribution()) {	176✔
284	// Create temporary distribution
285	DistEnergySab d;	132✔
286
287	// Copy outgoing energy distribution
288	d.n_e_out = edist.e_out.size();	132✔
289	d.e_out = edist.e_out;	132✔
290	d.e_out_pdf = edist.p;	132✔
291	d.e_out_cdf = edist.c;	132✔
292
293	for (int j = 0; j < d.n_e_out; ++j) {	660✔
294	auto adist = dynamic_cast<Tabular*>(edist.angle[j].get());	528!
295	if (adist) {	528!
296	// On first pass, allocate space for angles
297	if (j == 0) {	528✔
298	auto n_mu = adist->x().size();	132✔
299	d.mu = tensor::Tensor<double>({d.n_e_out, n_mu});	264✔
300	}
301
302	// Copy outgoing angles
303	tensor::View<double> mu_j = d.mu.slice(j);	528✔
304	std::copy(adist->x().begin(), adist->x().end(), mu_j.begin());	528✔
305	}	528✔
306	}
307
308	distribution_.emplace_back(std::move(d));	132✔
309	}	132✔
310	}	44✔
311
312	void IncoherentInelasticAE::sample_params(	3,614,897✔
313	double E_in, double& E_out, double& f, int& l, int& j, uint64_t* seed) const
314	{
315	// Get index and interpolation factor for inelastic grid
316	int i;	3,614,897✔
317	double f0;	3,614,897✔
318	get_energy_index(energy_, E_in, i, f0);	3,614,897✔
319
320	// Pick closer energy based on interpolation factor
321	l = f0 > 0.5 ? i + 1 : i;	3,614,897✔
322
323	// Determine outgoing energy bin
324	// (First reset n_energy_out to the right value)
325	int n = distribution_[l].n_e_out;	3,614,897✔
326	double r1 = prn(seed);	3,614,897✔
327	double c_j = distribution_[l].e_out_cdf[0];	3,614,897✔
328	double c_j1;	3,614,897✔
329	for (j = 0; j < n - 1; ++j) {	8,721,537!
330	c_j1 = distribution_[l].e_out_cdf[j + 1];	8,721,537✔
331	if (r1 < c_j1)	8,721,537✔
332	break;
333	c_j = c_j1;	5,106,640✔
334	}
335
336	// check to make sure j is <= n_energy_out - 2
337	j = std::min(j, n - 2);	3,614,897!
338
339	// Get the data to interpolate between
340	double E_l_j = distribution_[l].e_out[j];	3,614,897!
341	double p_l_j = distribution_[l].e_out_pdf[j];	3,614,897✔
342
343	// Next part assumes linear-linear interpolation in standard
344	double E_l_j1 = distribution_[l].e_out[j + 1];	3,614,897✔
345	double p_l_j1 = distribution_[l].e_out_pdf[j + 1];	3,614,897✔
346
347	// Find secondary energy (variable E)
348	double frac = (p_l_j1 - p_l_j) / (E_l_j1 - E_l_j);	3,614,897✔
349	if (frac == 0.0) {	3,614,897!
350	E_out = E_l_j + (r1 - c_j) / p_l_j;	3,614,897✔
351	} else {
UNCOV 352	E_out = E_l_j +	×
UNCOV 353	(std::sqrt(std::max(0.0, p_l_j * p_l_j + 2.0 * frac * (r1 - c_j))) -	×
UNCOV 354	p_l_j) /	×
355	frac;
356	}
357
358	// Adjustment of outgoing energy
359	double E_l = energy_[l];	3,614,897✔
360	if (E_out < 0.5 * E_l) {	3,614,897✔
361	E_out = 2.0 E_in / E_l - 1.0;	344,476✔
362	} else {
363	E_out += E_in - E_l;	3,270,421✔
364	}
365
366	f = (r1 - c_j) / (c_j1 - c_j);	3,614,897✔
367	}	3,614,897✔
368	void IncoherentInelasticAE::sample(	3,614,897✔
369	double E_in, double& E_out, double& mu, uint64_t* seed) const
370	{
371	double f;	3,614,897✔
372	int l, j;	3,614,897✔
373	sample_params(E_in, E_out, f, l, j, seed);	3,614,897✔
374
375	// Sample outgoing cosine bin
376	int n_mu = distribution_[l].mu.shape(1);	3,614,897!
377	std::size_t k = prn(seed) * n_mu;	3,614,897✔
378
379	// Rather than use the sampled discrete mu directly, it is smeared over
380	// a bin of width 0.5*min(mu[k] - mu[k-1], mu[k+1] - mu[k]) centered on the
381	// discrete mu value itself.
382	const auto& mu_l = distribution_[l].mu;	3,614,897✔
383
384	// Interpolate kth mu value between distributions at energies j and j+1
385	mu = mu_l(j, k) + f * (mu_l(j + 1, k) - mu_l(j, k));	3,614,897✔
386
387	// Inteprolate (k-1)th mu value between distributions at energies j and j+1.
388	// When k==0, pick a value that will smear the cosine out to a minimum of -1.
389	double mu_left =	3,614,897✔
390	(k == 0)
391	? mu_left = -1.0 - (mu + 1.0)	3,614,897✔
392	: mu_left = mu_l(j, k - 1) + f * (mu_l(j + 1, k - 1) - mu_l(j, k - 1));	3,159,464✔
393
394	// Inteprolate (k+1)th mu value between distributions at energies j and j+1.
395	// When k is the last discrete value, pick a value that will smear the cosine
396	// out to a maximum of 1.
397	double mu_right =	3,614,897✔
398	(k == n_mu - 1)	3,614,897✔
399	? mu_right = 1.0 + (1.0 - mu)	3,614,897✔
400	: mu_right = mu_l(j, k + 1) + f * (mu_l(j + 1, k + 1) - mu_l(j, k + 1));	3,160,762✔
401
402	// Smear cosine
403	mu += std::min(mu - mu_left, mu_right - mu) * (prn(seed) - 0.5);	5,427,510✔
404	}	3,614,897✔
405
UNCOV 406	double IncoherentInelasticAE::sample_energy_and_pdf(	×
407	double E_in, double mu, double& E_out, uint64_t* seed) const
408	{
UNCOV 409	double f;	×
UNCOV 410	int l, j;	×
UNCOV 411	sample_params(E_in, E_out, f, l, j, seed);	×
412
UNCOV 413	const auto& mu_l = distribution_[l].mu;	×
414
UNCOV 415	return get_pdf_discrete_interpolated(	×
UNCOV 416	mu_l.slice(j, tensor::all), mu_l.slice(j + 1, tensor::all), f, mu);	×
417	}
418
419	//==============================================================================
420	// MixedElasticAE implementation
421	//==============================================================================
422
423	MixedElasticAE::MixedElasticAE(	44✔
424	hid_t group, const CoherentElasticXS& coh_xs, const Function1D& incoh_xs)	44✔
425	: coherent_dist_(coh_xs), coherent_xs_(coh_xs), incoherent_xs_(incoh_xs)	44✔
426	{
427	// Read incoherent elastic distribution
428	hid_t incoherent_group = open_group(group, "incoherent");	44✔
429	std::string temp;	44✔
430	read_attribute(incoherent_group, "type", temp);	44✔
431	if (temp == "incoherent_elastic") {	44!
UNCOV 432	incoherent_dist_ = make_unique<IncoherentElasticAE>(incoherent_group);	×
433	} else if (temp == "incoherent_elastic_discrete") {	44!
434	auto xs = dynamic_cast<const Tabulated1D*>(&incoh_xs);	44✔
435	incoherent_dist_ =	44✔
436	make_unique<IncoherentElasticAEDiscrete>(incoherent_group, xs->x());	44✔
437	}
438	close_group(incoherent_group);	44✔
439	}	44✔
440
441	const AngleEnergy& MixedElasticAE::sample_dist(	46,486✔
442	double E_in, uint64_t* seed) const
443	{
444	// Evaluate coherent and incoherent elastic cross sections
445	double xs_coh = coherent_xs_(E_in);	46,486✔
446	double xs_incoh = incoherent_xs_(E_in);	46,486✔
447
448	if (prn(seed) * (xs_coh + xs_incoh) < xs_coh) {	46,486✔
449	return coherent_dist_;	45,144✔
450	} else {
451	return *incoherent_dist_;	1,342✔
452	}
453	}
454
455	void MixedElasticAE::sample(	46,486✔
456	double E_in, double& E_out, double& mu, uint64_t* seed) const
457	{
458	sample_dist(E_in, seed).sample(E_in, E_out, mu, seed);	46,486✔
459	}	46,486✔
460
UNCOV 461	double MixedElasticAE::sample_energy_and_pdf(	×
462	double E_in, double mu, double& E_out, uint64_t* seed) const
463	{
UNCOV 464	return sample_dist(E_in, seed).sample_energy_and_pdf(E_in, mu, E_out, seed);	×
465	}
466
467	} // namespace openmc

openmc-dev / openmc / 23460042813

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