# Unable to load chain\_endfb71.xml into depletion code **URL:** \ **Category:** User Support\ **Created:** [June 16, 2022, 6:27pm UTC](https://openmc.discourse.group/t/unable-to-load-chain-endfb71-xml-into-depletion-code/2123 "2022-06-16T18:27:54Z")\ **Posts on this page:** 7\ **Page:** 1
**Author:** ![myless](https://avatars.discourse-cdn.com/v4/letter/m/779978/32.png) [@myless](https://openmc.discourse.group/u/myless)\ **Post date:** [June 16, 2022, 6:27pm UTC](https://openmc.discourse.group/t/unable-to-load-chain-endfb71-xml-into-depletion-code/2123/1 "2022-06-16T18:27:54Z")
Hello, I am trying to run a depletion code example from John Shimwell’s neutronics-workshop repo, but am unable to load the xml file into the depletion operator. I used the generate\_endf71\_chain.py from the openmc-dev/data repo, and saved the xml file in the same path as my notebook. ```auto #Chain file setup chain_filename = 'chain_endfb71.xml' chain = openmc.deplete.Chain.from_xml(chain_filename) operator = openmc.deplete.Operator(model, chain_filename) #1e9 neutrons per second for 5 years then 5 years of no neutrons (shut down cooling time) time_steps = [365*24*60*60] * 5 + [365*24*60*60] * 5 source_rates = [1e9]*5 + [0] * 5 integrator = openmc.deplete.PredictorIntegrator( operator=operator, timesteps=time_steps,source_rates=source_rates ) integrator.integrate() --------------------------------------------------------------------------- OSError Traceback (most recent call last) Input In [12], in () 2 chain_filename = 'chain_endfb71.xml' 3 chain = openmc.deplete.Chain.from_xml(chain_filename) ----> 5 operator = openmc.deplete.Operator(model, chain_filename) 7 #1e9 neutrons per second for 5 years then 5 years of no neutrons (shut down cooling time) 9 time_steps = [365*24*60*60] * 5 + [365*24*60*60] * 5 File ~/.mambaforge3/envs/openmc/lib/python3.9/site-packages/openmc/deplete/operator.py:200, in Operator. __init__ (self, geometry, settings, chain_file, prev_results, diff_burnable_mats, normalization_mode, fission_q, dilute_initial, fission_yield_mode, fission_yield_opts, reaction_rate_mode, reaction_rate_opts, reduce_chain, reduce_chain_level) 198 warn("Fission Q dictionary will not be used") 199 fission_q = None --> 200 super(). __init__ (chain_file, fission_q, dilute_initial, prev_results) 201 self.round_number = False 202 self.settings = settings File ~/.mambaforge3/envs/openmc/lib/python3.9/site-packages/openmc/deplete/abc.py:113, in TransportOperator. __init__ (self, chain_file, fission_q, dilute_initial, prev_results) 111 break 112 else: --> 113 raise IOError( 114 "No chain specified, either manually or " 115 "under depletion_chain in environment variable " 116 "OPENMC_CROSS_SECTIONS.") 117 chain_file = lib['path'] 118 else: OSError: No chain specified, either manually or under depletion_chain in environment variable OPENMC_CROSS_SECTIONS. ``` The example I looked at initially had `chain_filename = '/chain_endfb71.xml'` , but I got the following error: ![image](https://global.discourse-cdn.com/free1/uploads/openmc/original/2X/8/8cc99a7d73d98e944d1ab7dd1c8b78302250406a.png) I also tried `chain_filename = './chain_endfb71.xml'`, but got the following error: ```auto --------------------------------------------------------------------------- OSError Traceback (most recent call last) Input In [11], in () 2 chain_filename = './chain_endfb71.xml' 3 chain = openmc.deplete.Chain.from_xml(chain_filename) ----> 5 operator = openmc.deplete.Operator(model, chain_filename) 7 #1e9 neutrons per second for 5 years then 5 years of no neutrons (shut down cooling time) 9 time_steps = [365*24*60*60] * 5 + [365*24*60*60] * 5 File ~/.mambaforge3/envs/openmc/lib/python3.9/site-packages/openmc/deplete/operator.py:200, in Operator. __init__ (self, geometry, settings, chain_file, prev_results, diff_burnable_mats, normalization_mode, fission_q, dilute_initial, fission_yield_mode, fission_yield_opts, reaction_rate_mode, reaction_rate_opts, reduce_chain, reduce_chain_level) 198 warn("Fission Q dictionary will not be used") 199 fission_q = None --> 200 super(). __init__ (chain_file, fission_q, dilute_initial, prev_results) 201 self.round_number = False 202 self.settings = settings File ~/.mambaforge3/envs/openmc/lib/python3.9/site-packages/openmc/deplete/abc.py:113, in TransportOperator. __init__ (self, chain_file, fission_q, dilute_initial, prev_results) 111 break 112 else: --> 113 raise IOError( 114 "No chain specified, either manually or " 115 "under depletion_chain in environment variable " 116 "OPENMC_CROSS_SECTIONS.") 117 chain_file = lib['path'] 118 else: OSError: No chain specified, either manually or under depletion_chain in environment variable OPENMC_CROSS_SECTIONS. ``` Curious to see where I went wrong here, should the xml file be saved somewhere in the openmc root folder? Thanks, Myles ---
**Author:** ![luizaldeia](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/luizaldeia/32/1824_2.png) [@luizaldeia](https://openmc.discourse.group/u/luizaldeia)\ **Post date:** [June 16, 2022, 8:44pm UTC](https://openmc.discourse.group/t/unable-to-load-chain-endfb71-xml-into-depletion-code/2123/2 "2022-06-16T20:44:13Z")
Hi Myles, have you tried running your code using one of the depletion chains you can download from the OpenMC page? ([Depletion Chains | OpenMC](https://openmc.org/depletion-chains/)) You can download the chain\_endfb71.xml file from here. best, Luiz ---
**Author:** ![myless](https://avatars.discourse-cdn.com/v4/letter/m/779978/32.png) [@myless](https://openmc.discourse.group/u/myless)\ **Post date:** [June 16, 2022, 8:51pm UTC](https://openmc.discourse.group/t/unable-to-load-chain-endfb71-xml-into-depletion-code/2123/3 "2022-06-16T20:51:07Z")
Hi Luiz, Thanks for your suggestion! I gave the endf\_pwr and endf\_sfr chains a try, and got the same error… with and without using . or / in the name. Best Myles ---
**Author:** ![luizaldeia](https://yyz2.discourse-cdn.com/free1/user_avatar/openmc.discourse.group/luizaldeia/32/1824_2.png) [@luizaldeia](https://openmc.discourse.group/u/luizaldeia)\ **Post date:** [June 16, 2022, 8:57pm UTC](https://openmc.discourse.group/t/unable-to-load-chain-endfb71-xml-into-depletion-code/2123/4 "2022-06-16T20:57:17Z")
Myles, could you please send me the model you’re using, so I can run it here to see what will happen. ---
**Author:** ![myless](https://avatars.discourse-cdn.com/v4/letter/m/779978/32.png) [@myless](https://openmc.discourse.group/u/myless)\ **Post date:** [June 17, 2022, 1:52pm UTC](https://openmc.discourse.group/t/unable-to-load-chain-endfb71-xml-into-depletion-code/2123/5 "2022-06-17T13:52:44Z")
Hi Luiz, Sorry for the delay, here’s a link to the example that I am following (for a sanity check I have even copied and pasted everything to make sure my implementation wasn’t incorrect, but I still get the same errors) > Best, Myles ---
**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:** [August 5, 2022, 3:44am UTC](https://openmc.discourse.group/t/unable-to-load-chain-endfb71-xml-into-depletion-code/2123/6 "2022-08-05T03:44:40Z")
@myless I think the problem is that you are using syntax for OpenMC version 0.13.0 (notably, passing a `Model` object to `Operator(...)`) but you are actually using version 0.12.2 or earlier (which expects a `Geometry` and `Materials` object. I would recommend updating your OpenMC installation to 0.13.0 and then trying again. ---
**Author:** ![myless](https://avatars.discourse-cdn.com/v4/letter/m/779978/32.png) [@myless](https://openmc.discourse.group/u/myless)\ **Post date:** [August 5, 2022, 4:32pm UTC](https://openmc.discourse.group/t/unable-to-load-chain-endfb71-xml-into-depletion-code/2123/7 "2022-08-05T16:32:47Z")
Hi Paul, Thanks for your reply. The newest version of OpenMC fixes this! Best, Myles