Hi all. I’m wondering how to go about finding radiation levels at a time after irradiation.
I have a high flux fast neutron source in a concrete room, which is on for a time, then switched off. I’d like to know what kind of radiation levels can be expected, say, an hour after the source has been switched off.
This is in order to determine when it is safe to enter the room.
I’m still fairly new here so I’m not sure how to go about this, if openmc even allows for it.
Thanks 
I would say this feature is still a research area and not quite ready for general usage.
You might find a few papers scattered around the internet where people report that they have added shut down dose rate simulations to their own local / private branches of OpenMC.
However you will be glad to hear there is a project where Paul, Patrick and Ethan are adding Shut down dose rate in a professional, tested, documented, manner to the OpenMC source code. I am also helping out with incremental additions whenever I spot an opportunity (e.g. 1, 2, 3 4) and am currently running and tweaking a few of these development workflows and hoping to put in a few more PRs in the future that bring us closer.
It is a really exciting feature to see added to OpenMC and the vertical integration where the transport and inventory calculations are done in a single code will have some advantages to other shut down dose rate options out there.
We would welcome any contributions in this area and are always keen on PRs, PR reviewers, people testing the workflow, bug reports, benchmarks (code to code and experiment vs code) if you are keen to see this feature become available sooner there are lots of opportunities to help accelerate this feature.
For the time being this minimal example cell based implementation might be of interest to you.
Thanks for your reply, that’s really cool to hear. I’ll take a look
Hi, been thinking more about this and I could achieve the same result by finding the amount of radioactive material produced in each cell. For example, I could find the amount of Re/Os produced in the WC reflector and use this to estimate the radiation levels.
With that in mind, does openmc allow one to tally the amount of a certain isotope produced from reaction? Is there a tally for, eg (n,Re)? I’m struggling to see based on the documentation.
Edit: found the section on depletion/transmutation. I was being daft 
Hi, sorry to bring this up again - I’ve tried running the shutdown dose rate code you linked in the neutronics workshop docker container. It’s having trouble reading the chain file.
I added the following:
import os
os.system(‘download_nndc_chain’)
openmc.config[‘chain_file’] = ‘chain-nndc-b7.1.xml’
(this is the same as used in ex14 depletion/transmutation)
but no joy. Any idea why it’s throwing this error and how I can fix it?
Edit: tried this:
import os
os.system(‘download_nndc_chain -r b8.0’)
openmc.config[‘chain_file’] = ‘chain-nndc-b8.0.xml’
throws error:
OSError: Error reading file ‘chain-nndc-b8.0.xml’: failed to load external entity “chain-nndc-b8.0.xml”
sorry about this, the error message is just saving it can’t find the chain file which is needed for depletion simulations
you could have a go at downloading a chain file with that same filename using this command executed in a notebook cell
!pip install openmc_data
!download_nndc_chain -r b7.1
Sorry to bring this up again, but I’m still having the same problem.
I’ve tried the following:
but still get the error:
OSError: Error reading file ‘chain-nndc-b8.0.xml’: failed to load external entity “chain-nndc-b8.0.xml”
I’ve tried using 7.1 and 8.0 but they throw the same error.
@srichr221 Can you check the directory where you’re running from and see if the chain-nndc-b8.0.xml file does indeed exist? If so, I would take a look at it and see if it looks like a normal XML file. I believe the error indicates that something is wrong with the file. If you attach it to this post, I can try it out myself to see if I get the same thing.
Thanks for your reply. I made the following change and it’s able to read the chain file and run:
Untitled1.py (15.0 KB)
However it’s now running into another issue:
And I’m not entirely sure what it means.
Again this is running in the neutronics workshop docker container; I’m just trying to run this example:
for my project investigating activation of a blanket module.
Hi @srichr221
That message means the code is trying to set the source strength to None which is not allowed.
Just to mention that example is not merged in because it is very early stages and as you can see not ready for wider use.
This workflow is in activate development and I hope there will be a better example in the future but at the moment we don’t have anything.
We welcome additions or improvements to help get this shut down dose rate workflow developed and really appreciate you giving this test script a go. I shall run your example and see if anything jumps as an easy fix.
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What do you reckon is my best alternative? I need to essentially find out the Activation of a blanket module mock-up to inform the safety procedures of my experiment (ie, if and when handling is possible after irradiation).
I could tally the radionuclides produced by just doing a depletion simulation but this wouldn’t tell me the dose someone would receive, which is what I really need.
To get the dose after a period of the time is going to require some coding, I don’t think there is an alternative to that.
If you can think of a way to contribute to the community effort and help speed it up that would be great.
Just posting here to link two threads as I think they are very similar and I’ve just posted an example on the other thread