Survival biasing:

```bash
./docs/source/io_formats/settings.rst:582:<survival_biasing> Element
./docs/source/io_formats/settings.rst:585:The <survival_biasing> element has no attributes and has an accepted value
./docs/source/io_formats/settings.rst:587:survival biasing, otherwise known as implicit capture or absorption.
./docs/source/methods/eigenvalue.rst:139:source contained in cell :math:i. To ensure that no bias is introduced, the
./docs/source/methods/parallelization.rst:370:method of successive generations) will be biased from the true fundamental
./docs/source/methods/parallelization.rst:373:per cycle is sufficiently large to neglect this bias.
./docs/source/methods/physics.rst:318:fission. If no survival biasing is being used, then the number of neutrons
./docs/source/methods/physics.rst:328:produced is biased in this manner so that the expected number of fission
./docs/source/methods/physics.rst:1588:biasing* or implicit absorption (or sometimes implicit capture, even though
./docs/source/methods/physics.rst:1591:In survival biasing, absorption reactions are prohibited from occurring and
./docs/source/methods/physics.rst:1596:  :label: survival-biasing-weight
./docs/source/methods/physics.rst:1602:handled differently if survival biasing is turned on. Although fission reactions
./docs/source/methods/physics.rst:1603:never actually occur with survival biasing, we still need to create fission
./docs/source/methods/physics.rst:1619:Additionally, since survival biasing can reduce the weight of the neutron to
./docs/source/methods/tallies.rst:95:by the volume of the region of integration. If survival biasing is employed, the
./docs/source/methods/tallies.rst:278::math:x_1, x_2, \dots, x_N, then an unbiased estimator for the population mean
./docs/source/methods/tallies.rst:294:distribution also known as the biased sample variance:
./docs/source/methods/tallies.rst:297:  :label: biased-variance
./docs/source/methods/tallies.rst:302:This estimator is biased because its expected value is actually not equal to the
./docs/source/methods/tallies.rst:306:  :label: biased-variance-expectation
./docs/source/methods/tallies.rst:312:correction_ to come up with an unbiased sample variance estimator: ./docs/source/methods/tallies.rst:315: :label: unbiased-variance ./docs/source/methods/tallies.rst:321:in equation :eq:unbiased-varianceis especially suitable for computation since ./docs/source/methods/tallies.rst:361:We can combine this result with equation :eq:unbiased-varianceto come up with ./docs/source/methods/tallies.rst:362:an unbiased estimator for the variance of the sample mean: ./docs/source/methods/tallies.rst:373:population based on equation :eq:unbiased-variancewill tend to the true ./docs/source/methods/tallies.rst:404::eq:unbiased-variance. If the random variables :math:X_i` are