# Molten salt reactor **URL:** \ **Category:** User Support\ **Created:** [May 26, 2022, 2:13pm UTC](https://openmc.discourse.group/t/molten-salt-reactor/2078 "2022-05-26T14:13:23Z")\ **Posts on this page:** 14\ **Page:** 1
**Author:** ![NaibOpenmc](https://avatars.discourse-cdn.com/v4/letter/n/8c91f0/32.png) [@NaibOpenmc](https://openmc.discourse.group/u/NaibOpenmc)\ **Post date:** [May 26, 2022, 2:13pm UTC](https://openmc.discourse.group/t/molten-salt-reactor/2078/1 "2022-05-26T14:13:23Z")
Hello! I am new to openmc. I am interested in modelling effective multiplication factor (keff) using different fuels of molten salt reactor. I am curious to know about how to find Keff of various LIQUID fuels in openmc. Also, any other advice would be highly appreciated. Thank You! ---
**Author:** ![paulromano](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/paulromano/32/486_2.png) [@paulromano](https://openmc.discourse.group/u/paulromano)\ **Post date:** [June 8, 2022, 11:50am UTC](https://openmc.discourse.group/t/molten-salt-reactor/2078/2 "2022-06-08T11:50:39Z")
@NaibOpenmc I would recommend the follow resources for you as a beginner: - [User’s guide](https://docs.openmc.org/en/stable/usersguide/index.html) - [Example Jupyter notebooks](https://github.com/openmc-dev/openmc/wiki/Example-Jupyter-Notebooks) After reading through the user’s guide and taking a look at some of the examples, let us know if you have more specific questions. ---
**Author:** ![NaibOpenmc](https://avatars.discourse-cdn.com/v4/letter/n/8c91f0/32.png) [@NaibOpenmc](https://openmc.discourse.group/u/NaibOpenmc)\ **Post date:** [July 8, 2022, 1:53pm UTC](https://openmc.discourse.group/t/molten-salt-reactor/2078/3 "2022-07-08T13:53:16Z")
I have studied the FSR example but it has solid fuel…can you please suggest me any example code that has implemented liquid thorium fuel breeder reactor? I badly need this for my undergrad thesis work. Thank You ---
**Author:** ![paulromano](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/paulromano/32/486_2.png) [@paulromano](https://openmc.discourse.group/u/paulromano)\ **Post date:** [July 8, 2022, 2:29pm UTC](https://openmc.discourse.group/t/molten-salt-reactor/2078/4 "2022-07-08T14:29:26Z")
I am personally not aware of any such models that are available, unfortunately. ---
**Author:** ![NaibOpenmc](https://avatars.discourse-cdn.com/v4/letter/n/8c91f0/32.png) [@NaibOpenmc](https://openmc.discourse.group/u/NaibOpenmc)\ **Post date:** [August 30, 2022, 5:10am UTC](https://openmc.discourse.group/t/molten-salt-reactor/2078/5 "2022-08-30T05:10:19Z")
hi! while using graphite as a moderator in molten salt reactor openmc does not find cross section data for carbon. Why is that so? How to fix this problem? thanks ![Screenshot 2022-08-30 at 11.06.59 AM](https://global.discourse-cdn.com/free1/uploads/openmc/original/2X/a/af7208a034b8b6eed84f1fcf1dc9c7c72344c63c.jpeg) Uploading: Screenshot 2022-08-30 at 11.07.22 AM.png… ---
**Author:** ![tjlaboss](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/tjlaboss/32/1390_2.png) [@tjlaboss](https://openmc.discourse.group/u/tjlaboss)\ **Post date:** [August 31, 2022, 2:22pm UTC](https://openmc.discourse.group/t/molten-salt-reactor/2078/6 "2022-08-31T14:22:58Z")
Depending which cross section library you are using, carbon may be elementwise. Check the `cross_sections.xml` you are using. It probably has C0 (elemental carbon) instead of C12. ---
**Author:** ![NaibOpenmc](https://avatars.discourse-cdn.com/v4/letter/n/8c91f0/32.png) [@NaibOpenmc](https://openmc.discourse.group/u/NaibOpenmc)\ **Post date:** [September 3, 2022, 9:17am UTC](https://openmc.discourse.group/t/molten-salt-reactor/2078/7 "2022-09-03T09:17:38Z")
yes! then should I write openmc.add\_element (‘C0’,1,‘ao’) instead of openmc.add\_element(‘C’,1,‘ao’) ? ---
**Author:** ![tjlaboss](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/tjlaboss/32/1390_2.png) [@tjlaboss](https://openmc.discourse.group/u/tjlaboss)\ **Post date:** [September 3, 2022, 2:45pm UTC](https://openmc.discourse.group/t/molten-salt-reactor/2078/8 "2022-09-03T14:45:31Z")
Are you using `add_nuclide()`, or `add_element()`? If it’s `add_element()`, looks to me like the `openmc` module and OpenMC itself are seeing a different _cross\_sections.xml_. Check your `OPENMC_CROSS_SECTIONS` environment variable and refer to the documentation for `openmc.Element` here: [https://docs.openmc.org/en/latest/pythonapi/generated/openmc.Element.html](https://docs.openmc.org/en/latest/pythonapi/generated/openmc.Element.html) ---
**Author:** ![NaibOpenmc](https://avatars.discourse-cdn.com/v4/letter/n/8c91f0/32.png) [@NaibOpenmc](https://openmc.discourse.group/u/NaibOpenmc)\ **Post date:** [September 4, 2022, 2:06pm UTC](https://openmc.discourse.group/t/molten-salt-reactor/2078/9 "2022-09-04T14:06:55Z")
thanks! That problem has been solved. However, I am facing another problem: I cannot plot a 2D geometry either by plot inline function or plot.geometry() function. except for the plot the whole code runs smoothly. please see the attached images ![Screenshot 2022-09-04 at 8.00.04 PM|690x412](upload://d2 ![Screenshot 2022-09-04 at 8.01.42 PM](https://global.discourse-cdn.com/free1/uploads/openmc/original/2X/e/e112f114f76c5f6358f5c03f4307972b92d15927.png) x3dKf1SgewUJNFGggZX6LJsnO.png) ![Screenshot 2022-09-04 at 8.01.55 PM](https://global.discourse-cdn.com/free1/uploads/openmc/original/2X/f/f2df26d48fdf498a2b4749eebb4359bd1bb5a703.png) ---
**Author:** ![tjlaboss](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/tjlaboss/32/1390_2.png) [@tjlaboss](https://openmc.discourse.group/u/tjlaboss)\ **Post date:** [September 6, 2022, 6:30pm UTC](https://openmc.discourse.group/t/molten-salt-reactor/2078/10 "2022-09-06T18:30:05Z")
That’s probably indicative of a geometry error, which is something you would have to debug yourself. The simpler your geometry, the easier it will be, so start with a single cell of your lattice and work up from there. ---
**Author:** ![paulromano](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/paulromano/32/486_2.png) [@paulromano](https://openmc.discourse.group/u/paulromano)\ **Post date:** [September 7, 2022, 4:19pm UTC](https://openmc.discourse.group/t/molten-salt-reactor/2078/11 "2022-09-07T16:19:16Z")
To add on to @tjlaboss’s comment, please have a look at the user’s guide section on [geometry debugging](https://docs.openmc.org/en/latest/usersguide/troubleshoot.html#geometry-debugging) if you haven’t already. ---
**Author:** ![NaibOpenmc](https://avatars.discourse-cdn.com/v4/letter/n/8c91f0/32.png) [@NaibOpenmc](https://openmc.discourse.group/u/NaibOpenmc)\ **Post date:** [December 28, 2022, 10:16am UTC](https://openmc.discourse.group/t/molten-salt-reactor/2078/12 "2022-12-28T10:16:13Z")
![Screenshot 2022-12-28 at 4.13.16 PM](https://global.discourse-cdn.com/free1/uploads/openmc/original/2X/f/fb7977900bc90334da1f0e41185fb6c3ef7fc200.jpeg) can anyone please enlighten me as to why openmc aborting the operation? ---
**Author:** ![paulromano](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/paulromano/32/486_2.png) [@paulromano](https://openmc.discourse.group/u/paulromano)\ **Post date:** [December 31, 2022, 2:51am UTC](https://openmc.discourse.group/t/molten-salt-reactor/2078/13 "2022-12-31T02:51:59Z")
When you encounter this error, what information is shown in the associated terminal from which the Jupyter notebook is run? This looks to be an issue related to a DAGMC geometry. Perhaps one of our DAGMC experts (@pshriwise @Shimwell) can chime in with further ideas. ---
**Author:** ![Shimwell](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/shimwell/32/3876_2.png) [@Shimwell](https://openmc.discourse.group/u/Shimwell)\ **Post date:** [December 31, 2022, 3:03am UTC](https://openmc.discourse.group/t/molten-salt-reactor/2078/14 "2022-12-31T03:03:25Z")
Hard to say what is going wrong, perhaps the terminal messages will help. One easy option to try in the meantime would be to improve the model faceting tolerance from the current 0.01 when constructing the geometry. It might be worth decreasing this number a bit more to as it can sometimes solve a mesh overlap or geometry problem. I think that 1e-6 is about as low as one would ever need to go for the faceting tolerance but it does increase the model size unfortunately. I’m guessing the geometry was converted to h5m with Cubit. It might also be worth trying the cubit commands to heal the geometry prior to exporting as h5m ```auto cubit.cmd("healer autoheal vol all") ```