# About Prompt Neutron Lifetime Calculation

**URL:** <https://openmc.discourse.group/t/about-prompt-neutron-lifetime-calculation/5238>\
**Category:** User Support\
**Created:** [February 13, 2025, 12:20pm UTC](https://openmc.discourse.group/t/about-prompt-neutron-lifetime-calculation/5238 "2025-02-13T12:20:41Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![ozgur.hanci](https://avatars.discourse-cdn.com/v4/letter/o/e9c0ed/32.png) [@ozgur.hanci](https://openmc.discourse.group/u/ozgur.hanci)\
**Post date:** [February 13, 2025, 12:20pm UTC](https://openmc.discourse.group/t/about-prompt-neutron-lifetime-calculation/5238/1 "2025-02-13T12:20:42Z")

</div>

Dear experts,

I am still on the learning path and I’m currently struggling to get PNL. The same issue is mentioned in [another topic](https://openmc.discourse.group/t/prompt-neutron-lifetime/4853) but I couldn’t make it work since I’m not very familiar with usage of property objects and it asks for a “states” parameter for pnl() function to operate where I couldn’t figure out what should I feed it with. My intention is to get the PNL value for Jezebel assembly (just as in example file) to test and compare the results but I am not sure which tallies I should be using.

Also in some papers I saw usage of OpenMC(TD) to get Rossi-alpha values, is it an openly accessible version?

I appreciate all the help regarding PNL calculation of Jezebel.

Thanks!