Change power density in automated burnup sequence

Discussion on physics, models and calculation methods
Ana Jambrina
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Re: Change power density in automated burnup sequence

To model a non-irradiated period, you could either directly use a decay step, skipping the neutron transport calculation, or explicitly perform a burnup calculation with zero power. However, if you aim to obtain some detector output from that step, you should set a burnup step with very low power, e.g., 1E-6.
- Ana

novako
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Re: Change power density in automated burnup sequence

Thank you Ana,
I want to calculate decay heat during the decay time.
My goal is to calculate maximum decay heat during "summer outage" for single fuel assembly. And how should I set the decay heat calculation ( I did not find that in manual/wiki)?
Thank you

Antti Rintala
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Re: Change power density in automated burnup sequence

You can achieve that by calculating decay steps with dep decstep restarting from a burnup calculation at the correct burnup.

Ana Jambrina
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Re: Change power density in automated burnup sequence

The (instantaneous) decay heat is one of the parameters printed out in the ‘_dep.m’ file for each of the depleted materials, MAT_[NAME]_H, or total, TOT_H, for each of the depletion history steps.
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novako
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Re: Change power density in automated burnup sequence

Hi,
I misunderstood and used one calculation with mixture of dep butot and dep daystep. Like this

Code: Select all

``````dep butot
0.0001
0.09
0.26
0.5
1
...
70
dep daystep
0.1
0.1
...
30
30
30
30
30
``````
This however did not calculated the just decay after 70 MWd/kg. But continued in full power, reaching burnup of 7.93915E+01. How can I change the power during those decay steps to have it zero, as you recommended in one of previous comments? Thank you

Ana Jambrina
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Re: Change power density in automated burnup sequence

The idea is to modify the depletion (power) history. Thus, change the normalization at the decay step: e.g., use the normalization ‘set power’ with a small value, 1E-6, (or zero). Alternatively, instead of using a burnup step ('bustep'/'butot', 'daystep'/'daytot'), use a decay step ('decstep'/'dectot'). In this case, there is no need of changing the normalization - see the 'dep' card.
- Ana