# How a nuclear reactor makes electricity

> A process map exported from forks.world (https://forks.world). Author: Brian. Source: https://forks.world/p/cmv0kpxju000ojv06uvs5s547
> It describes who does what, in what order, and with which technology. Read the plain-language sections first; the JSON at the end is the exact, complete data.

## Summary

- 16 steps across 2 layers
- Persona: Operators
- Technology / systems: Reactor core, Control rods, Cooling water, Turbine and generator

## Pain points

Where this process hurts, worst first:

- **Spent fuel stays radioactive for a very long time** (How a nuclear reactor makes electricity; painful): Debated: long-term storage and safety

## How to read this file

- A process is made of **layers**. The main layer is the top level; any step of kind `subprocess` opens a detail layer with its own lanes and steps.
- **Lanes** are either persona (people/roles) or technology (systems). Each step belongs to one lane; `using` lists tools a person uses for that step.
- Step kinds: `start`, `task`, `decision` (its arrows carry the answer as a label), `subprocess`, `end`.

## How a nuclear reactor makes electricity

Lanes:
- Reactor core: technology / system (id `core`)
- Control rods: technology / system (id `control`)
- Cooling water: technology / system (id `water`)
- Turbine and generator: technology / system (id `turbine`)
- Operators: person / role (id `crew`)

Steps, in the order they run:

1. **A neutron hits a uranium-235 atom** [start; Reactor core; id `r1`]
   - then It splits, releasing heat and more neutrons
2. **It splits, releasing heat and more neutrons** [task; Reactor core; id `r2`]
   - then More neutrons split more atoms: a chain reaction
3. **More neutrons split more atoms: a chain reaction** [task; Reactor core; id `r3`]
   - then Is the reaction running too fast?
4. **Is the reaction running too fast?** [decision; Operators; id `r4`]
   - if "Yes" go to Insert the control rods to absorb neutrons; if "No" go to Raise the rods slightly to hold the power steady
5. **Insert the control rods to absorb neutrons** [task; Control rods; id `r5`]
   - then Water carries the heat away
6. **Water carries the heat away** [task; Cooling water; id `r6`]
   - then Steam spins a turbine
7. **Steam spins a turbine** [task; Turbine and generator; id `r7`]
   - then A generator makes electricity
8. **A generator makes electricity** [task; Turbine and generator; id `r8`]
   - then Spent fuel stays radioactive for a very long time
9. **Spent fuel stays radioactive for a very long time** [subprocess; Operators; id `r9`] ⚠ PAIN POINT (painful): Debated: long-term storage and safety, opens the detail layer "What happens to the waste"
   - then Cooling continues even after shutdown
10. **Cooling continues even after shutdown** [end; Operators; id `r10`]
11. **Raise the rods slightly to hold the power steady** [task; Control rods; id `r4a`]
   - then Water carries the heat away

```mermaid
flowchart LR
  subgraph l_core["Reactor core"]
    n_r1(["A neutron hits a uranium-235 atom"])
    n_r2["It splits, releasing heat and more neutrons"]
    n_r3["More neutrons split more atoms: a chain reaction"]
  end
  subgraph l_control["Control rods"]
    n_r4a["Raise the rods slightly to hold the power steady"]
    n_r5["Insert the control rods to absorb neutrons"]
  end
  subgraph l_water["Cooling water"]
    n_r6["Water carries the heat away"]
  end
  subgraph l_turbine["Turbine and generator"]
    n_r7["Steam spins a turbine"]
    n_r8["A generator makes electricity"]
  end
  subgraph l_crew["Operators"]
    n_r4{"Is the reaction running too fast?"}
    n_r9[["Spent fuel stays radioactive for a very long time"]]
    n_r10(["Cooling continues even after shutdown"])
  end
  n_r1 --> n_r2
  n_r2 --> n_r3
  n_r3 --> n_r4
  n_r4 -->|"Yes"| n_r5
  n_r4 -->|"No"| n_r4a
  n_r4a --> n_r6
  n_r5 --> n_r6
  n_r6 --> n_r7
  n_r7 --> n_r8
  n_r8 --> n_r9
  n_r9 --> n_r10
```

### What happens to the waste (detail of step "Spent fuel stays radioactive for a very long time")

Lanes:
- Operators: person / role (id `crew`)

Steps, in the order they run:

1. **The fuel cools in a pool for years** [start; Operators; id `w1`]
   - then Move it into dry steel and concrete casks
2. **Move it into dry steel and concrete casks** [task; Operators; id `w2`]
   - then Is there a permanent repository?
3. **Is there a permanent repository?** [decision; Operators; id `w3`]
   - if "Yes" go to It goes underground for the long term; if "Not yet in many countries" go to It stays stored on site
4. **It goes underground for the long term** [end; Operators; id `w4`]
5. **It stays stored on site** [end; Operators; id `w5`]

```mermaid
flowchart LR
  subgraph l_crew["Operators"]
    n_w1(["The fuel cools in a pool for years"])
    n_w2["Move it into dry steel and concrete casks"]
    n_w3{"Is there a permanent repository?"}
    n_w5(["It stays stored on site"])
    n_w4(["It goes underground for the long term"])
  end
  n_w1 --> n_w2
  n_w2 --> n_w3
  n_w3 -->|"Yes"| n_w4
  n_w3 -->|"Not yet in many countries"| n_w5
```

## Full data (JSON)

```json
{
  "title": "How a nuclear reactor makes electricity",
  "maps": {
    "m_root": {
      "id": "m_root",
      "lanes": [
        {
          "id": "core",
          "name": "Reactor core",
          "type": "system"
        },
        {
          "id": "control",
          "name": "Control rods",
          "type": "system"
        },
        {
          "id": "water",
          "name": "Cooling water",
          "type": "system"
        },
        {
          "id": "turbine",
          "name": "Turbine and generator",
          "type": "system"
        },
        {
          "id": "crew",
          "name": "Operators",
          "type": "person"
        }
      ],
      "steps": [
        {
          "id": "r1",
          "kind": "start",
          "lane": "core",
          "next": [
            {
              "to": "r2"
            }
          ],
          "uses": [],
          "label": "A neutron hits a uranium-235 atom"
        },
        {
          "id": "r2",
          "kind": "task",
          "lane": "core",
          "next": [
            {
              "to": "r3"
            }
          ],
          "uses": [],
          "label": "It splits, releasing heat and more neutrons"
        },
        {
          "id": "r3",
          "kind": "task",
          "lane": "core",
          "next": [
            {
              "to": "r4"
            }
          ],
          "uses": [],
          "label": "More neutrons split more atoms: a chain reaction"
        },
        {
          "id": "r4",
          "kind": "decision",
          "lane": "crew",
          "next": [
            {
              "to": "r5",
              "label": "Yes"
            },
            {
              "to": "r4a",
              "label": "No"
            }
          ],
          "uses": [],
          "label": "Is the reaction running too fast?"
        },
        {
          "id": "r4a",
          "kind": "task",
          "lane": "control",
          "next": [
            {
              "to": "r6"
            }
          ],
          "uses": [],
          "label": "Raise the rods slightly to hold the power steady"
        },
        {
          "id": "r5",
          "kind": "task",
          "lane": "control",
          "next": [
            {
              "to": "r6"
            }
          ],
          "uses": [],
          "label": "Insert the control rods to absorb neutrons"
        },
        {
          "id": "r6",
          "kind": "task",
          "lane": "water",
          "next": [
            {
              "to": "r7"
            }
          ],
          "uses": [],
          "label": "Water carries the heat away"
        },
        {
          "id": "r7",
          "kind": "task",
          "lane": "turbine",
          "next": [
            {
              "to": "r8"
            }
          ],
          "uses": [],
          "label": "Steam spins a turbine"
        },
        {
          "id": "r8",
          "kind": "task",
          "lane": "turbine",
          "next": [
            {
              "to": "r9"
            }
          ],
          "uses": [],
          "label": "A generator makes electricity"
        },
        {
          "id": "r9",
          "kind": "subprocess",
          "lane": "crew",
          "next": [
            {
              "to": "r10"
            }
          ],
          "pain": {
            "note": "Debated: long-term storage and safety",
            "level": 2
          },
          "uses": [],
          "child": "m_waste",
          "label": "Spent fuel stays radioactive for a very long time"
        },
        {
          "id": "r10",
          "kind": "end",
          "lane": "crew",
          "next": [],
          "uses": [],
          "label": "Cooling continues even after shutdown"
        }
      ],
      "title": "How a nuclear reactor makes electricity",
      "parent": null
    },
    "m_waste": {
      "id": "m_waste",
      "lanes": [
        {
          "id": "crew",
          "name": "Operators",
          "type": "person"
        }
      ],
      "steps": [
        {
          "id": "w1",
          "kind": "start",
          "lane": "crew",
          "next": [
            {
              "to": "w2"
            }
          ],
          "uses": [],
          "label": "The fuel cools in a pool for years"
        },
        {
          "id": "w2",
          "kind": "task",
          "lane": "crew",
          "next": [
            {
              "to": "w3"
            }
          ],
          "uses": [],
          "label": "Move it into dry steel and concrete casks"
        },
        {
          "id": "w3",
          "kind": "decision",
          "lane": "crew",
          "next": [
            {
              "to": "w4",
              "label": "Yes"
            },
            {
              "to": "w5",
              "label": "Not yet in many countries"
            }
          ],
          "uses": [],
          "label": "Is there a permanent repository?"
        },
        {
          "id": "w5",
          "kind": "end",
          "lane": "crew",
          "next": [],
          "uses": [],
          "label": "It stays stored on site"
        },
        {
          "id": "w4",
          "kind": "end",
          "lane": "crew",
          "next": [],
          "uses": [],
          "label": "It goes underground for the long term"
        }
      ],
      "title": "What happens to the waste",
      "parent": {
        "map": "m_root",
        "step": "r9"
      }
    }
  }
}
```