# surface current score issue openmc 0.10

**URL:** <https://openmc.discourse.group/t/surface-current-score-issue-openmc-0-10/435>\
**Category:** User Support\
**Created:** [April 28, 2019, 10:32am UTC](https://openmc.discourse.group/t/surface-current-score-issue-openmc-0-10/435 "2019-04-28T10:32:29Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![Umair\_Aziz1](https://avatars.discourse-cdn.com/v4/letter/u/a4c791/32.png) [@Umair\_Aziz1](https://openmc.discourse.group/u/Umair_Aziz1)\
**Post date:** [April 28, 2019, 10:32am UTC](https://openmc.discourse.group/t/surface-current-score-issue-openmc-0-10/435/1 "2019-04-28T10:32:29Z")

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hi

i am having a problem with openmc 0.10 while tallying for surface current of a 3 sphere geometry in a fixed source run

when i do not specify any source energy distribution, the simulation runs fine by taking a default watt distribution with a=0.988 and b=2.246 as specified in user guide of the openmc, but when i specify even the same source distribution i.e. watt with a=0.988 and b=2.246 there are no results. with some troubleshooting i found out that when i specify the energy element i do not get the proper source data bank therefore no current result.

i tried default values because at first i specified my own values for a and b; i.e. 1.025 and 2.926 for a cf252 source spectrum and got zero as result, therefore i tried writing the exact same values as default (like the values taken by openmc in case of no energy element in settings file).

please see attached files and if anyone can help me where i am going wrong?

i am interested to find out the current passing through surface 3 of the geometry.

thanks

[geometry.xml](https://openmc.discourse.group/uploads/short-url/iNO23clSVcj8AtBG5JmdYT5MY0.xml) (615 Bytes)

[materials.xml](https://openmc.discourse.group/uploads/short-url/y8dXzWVXTP1hVKiz3mXpihaZYLJ.xml) (548 Bytes)

[plots.xml](https://openmc.discourse.group/uploads/short-url/hOmZDC4Vh97063gBqOqDzHtKgoO.xml) (376 Bytes)

[settings.xml](https://openmc.discourse.group/uploads/short-url/2WXLE1IsYXk3ycle4tFB2mJ0QKE.xml) (374 Bytes)

[tallies.xml](https://openmc.discourse.group/uploads/short-url/wKen9mUItTI12aYtRQzs0XHfNRm.xml) (896 Bytes)

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**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:** [April 29, 2019, 12:42pm UTC](https://openmc.discourse.group/t/surface-current-score-issue-openmc-0-10/435/2 "2019-04-29T12:42:12Z")

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When you specify the parameters for the Watt distribution, note that they must be in units of eV and eV^-1, not MeV and MeV^-1. So, the proper constants would be 0.988e6 and 2.249e-6. For your Cf252 source, you should use 1.025e6 and 2.926e-6.

Best regards,  
Paul

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**Author:** ![Umair\_Aziz1](https://avatars.discourse-cdn.com/v4/letter/u/a4c791/32.png) [@Umair\_Aziz1](https://openmc.discourse.group/u/Umair_Aziz1)\
**Post date:** [April 29, 2019, 1:40pm UTC](https://openmc.discourse.group/t/surface-current-score-issue-openmc-0-10/435/3 "2019-04-29T13:40:31Z")

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oh! such a silly mistake at my end. i tried with e6 since i knew that openmc now has defaults of eV but failed to do the e-6 for b.

thankyou