Add a simple nuclear plant performance and cost model by johnjasa · Pull Request #538 · NatLabRockies/H2Integrate

johnjasa · 2026-02-19T22:15:18Z

Add a simple nuclear plant performance and cost model

We often get asked if we have a nuclear plant model in H2I.
This PR introduces an extremely simple model based on Quinn et al.

This model only produces electricity and outputs costs based on scaling factors.
It's up to the user to use reasonable cost inputs; there are no defaults assumed here.
Because of this generality, this plant could be seen as LWR or SMR or any other architecture.

Section 1: Type of Contribution

Section 3: General PR Checklist

PR description thoroughly describes the new feature, bug fix, etc.
Added tests for new functionality or bug fixes
Tests pass (If not, and this is expected, please elaborate in the Section 6: Test Results)
Documentation
- Docstrings are up-to-date
- Related docs/ files are up-to-date, or added when necessary
- Documentation has been rebuilt successfully
- Examples have been updated (if applicable)
CHANGELOG.md has been updated to describe the changes made in this PR

Section 3: Related Issues

Section 4: Impacted Areas of the Software

Section 5: Additional Supporting Information

Section 6: Test Results, if applicable

Section 7 (Optional): New Model Checklist

into simple_nuclear

elenya-grant

Nice clean PR! Thanks John! I have one question that I'd be interested in your response on (related to the cost model) before approving but it looks good!

elenya-grant · 2026-02-26T16:19:03Z

h2integrate/converters/nuclear/nuclear_plant.py

+    Args:
+        system_capacity_mw (float): Rated electric capacity in MW.
+        reactor_type (str): Key selecting a reactor type in type_costs.
+        type_costs (dict): Reactor type cost data with keys:


Why have type_costs as a dict instead of having the keys in type_costs be attributes of NuclearCostModelConfig? I understand the convince of having different costs dictionaries in the tech config so that the costs can be easily changed by just changing the reactor_type.

Alternatives to the imbedded dictionaries would be to use the modify_tech_config function or having a different file set-up where it's easy to switch the cost parameters.

I'm just curious - not necessarily asking for a change.

You know what, I don't think there's a great reason to have the costs specified differently here. I've made them directly part of the cost config. Thanks for the good question! I think it was just a holdover in logic from me trying out different reactor_types, which should be handled at the config level instead.

elenya-grant · 2026-02-26T16:19:18Z

examples/08_wind_electrolyzer/plant_config.yaml

-# array of arrays containing left-to-right technology
-# interconnections; can support bidirectional connections
-# with the reverse definition.
-# this will naturally grow as we mature the interconnected tech


thanks for cleaning up this example file!

…mple_nuclear

elenya-grant

Thanks for the quick change!

elenya-grant · 2026-02-26T17:55:58Z

h2integrate/converters/nuclear/nuclear_plant.py

+        system_capacity_mw (float): Rated electric capacity in MW.
+        capex_per_kw (float): Capital cost per kW.
+        fixed_opex_per_kw_year (float): Fixed O&M per kW per year.
+        variable_opex_per_mwh (float): Variable O&M per MWh.


thanks for updating this!

jaredthomas68

Looks pretty good. I just have a few comments to be addressed.

jaredthomas68 · 2026-02-26T19:11:08Z

docs/technology_models/nuclear.md

+C_{\text{capex}} = (c_{\text{capex}} \cdot (P / P_{\text{ref}})^{(e-1)}) \cdot P
+$$
+
+Where $c_{\text{capex}}$ is `capex_per_kw`, $P$ is plant capacity (kW), $P_{\text{ref}}$ is `reference_capacity_mw`, and $e$ is `capex_scaling_exponent`.


I would avoid using $e$ in the equation unless it is Euler's number

jaredthomas68 · 2026-02-26T19:14:13Z

docs/technology_models/nuclear.md

+Cost defaults are intended to be populated from literature, such as Quinn et al. (2023) on SMR LWR techno-economic analysis.
+See the paper here: https://doi.org/10.1016/j.apenergy.2023.120669.


I suggest using markdown reference here linking to the reference given at the bottom and moving the url to the references section.

jaredthomas68 · 2026-02-26T19:16:05Z

docs/user_guide/model_overview.md

        + `'NaturalGasCostModel'`
+- `nuclear`: nuclear power plant
+    - performance models:
+        + `'NuclearPerformanceModel'`


Would it make since to delineate this as the QuinnNuclearPerformanceModel or something similar to make room for future nuclear models?

jaredthomas68 · 2026-02-26T19:20:44Z

h2integrate/converters/nuclear/test/test_nuclear_plant.py

+    prob.set_val("system_capacity", system_capacity)
+    prob.set_val("electricity_out", electricity_out)
+    prob.run_model()
+
+    capex = prob.get_val("CapEx")[0]
+    opex = prob.get_val("OpEx")[0]
+    cost_year = prob.get_val("cost_year")


Can you specify units here?

jaredthomas68 · 2026-02-26T19:21:54Z

h2integrate/converters/nuclear/nuclear_plant.py

+
+    The model limits output by a fixed capacity factor and optional demand profile.
+
+    Based on Quinn, J. et al., 2023.


Thanks for including the source in the doc string

jaredthomas68 · 2026-02-26T19:25:53Z

h2integrate/converters/nuclear/nuclear_plant.py

+        capex_scaling_exponent = self.config.capex_scaling_exponent
+
+        system_capacity_mw = inputs["system_capacity"]
+        capacity_kw = system_capacity_mw * 1000


Why use MW in inputs if you later convert to kW? Given that most other techs use kW, it may make more sense. Non-blocking.

Good call, modified!

johnjasa added 8 commits February 17, 2026 23:25

Added first pass at a simple nuclear model

e1aa77c

Adding nuclear doc page

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Added to changelog

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Merge branch 'develop' into simple_nuclear

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Doc cleanup

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Merge branch 'develop' into simple_nuclear

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Merge branch 'simple_nuclear' of https://github.com/johnjasa/H2Integrate

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into simple_nuclear

Fixed OpEx calc for nuclear

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johnjasa requested review from elenya-grant and jaredthomas68 February 24, 2026 20:42

johnjasa added 3 commits February 25, 2026 16:25

Merge branch 'develop' into simple_nuclear

7ab03d1

Simplifying nuclear test

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Merge branch 'develop' into simple_nuclear

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elenya-grant reviewed Feb 26, 2026

View reviewed changes

johnjasa added 4 commits February 26, 2026 09:56

Merge branch 'develop' of https://github.com/NREL/H2Integrate into si…

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…mple_nuclear

Addressing PR comments

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Merge branch 'develop' into simple_nuclear

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Marking tests

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johnjasa added the ready for review This PR is ready for input from folks label Feb 26, 2026

elenya-grant self-requested a review February 26, 2026 17:55

elenya-grant approved these changes Feb 26, 2026

View reviewed changes

Merging

07c9119

jaredthomas68 requested changes Feb 26, 2026

View reviewed changes

Updates based on PR feedback

832cb6a

		Cost defaults are intended to be populated from literature, such as Quinn et al. (2023) on SMR LWR techno-economic analysis.
		See the paper here: https://doi.org/10.1016/j.apenergy.2023.120669.


		The model limits output by a fixed capacity factor and optional demand profile.

		Based on Quinn, J. et al., 2023.

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Add a simple nuclear plant performance and cost model

Section 1: Type of Contribution

Section 3: General PR Checklist

Section 3: Related Issues

Section 4: Impacted Areas of the Software

Section 5: Additional Supporting Information

Section 6: Test Results, if applicable

Section 7 (Optional): New Model Checklist

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johnjasa commented Feb 19, 2026 •

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