@ferret/physics-nuclear

Assembly class

class Assembly

packages/physics-nuclear/src/assembly.ts:34

Fallout class

class Fallout

What a release leaves on the ground: a grid of cells, each with its own inventory that decays exactly like any other, so a cell that holds Cs-137 loses its activity by the half-life and one that holds Ba-137m next to it keeps the daughter in step. Washing (rain, a hose) takes a share of every isotope off a cell, to a sink that is not tracked here.

packages/physics-nuclear/src/fallout.ts:9

Inventory class

class Inventory

Atoms of each isotope in a body, a vessel or a patch of soil.

packages/physics-nuclear/src/decay.ts:108

IsotopeLibrary class

class IsotopeLibrary

packages/physics-nuclear/src/decay.ts:49

Reactor class

class Reactor

packages/physics-nuclear/src/reactor.ts:84

ShieldLibrary class

class ShieldLibrary

packages/physics-nuclear/src/radiation.ts:35

activate function

function activate(inv: Inventory, captures: readonly Capture[], flux: number, dt: number): number

Neutron activation. A flux Φ (neutrons per m² and s) turns the nuclei of a target into its radioactive product at the rate σ Φ per nucleus: N_to gains N_from (1 - e^(-σΦt)) over t and the target loses the same, so what is made is never more than there was. The product then decays with the rest of the inventory (call inv.decay(dt) after this, which makes the activity rise to the saturation value N_from σ Φ and no further). Returns the atoms made.

packages/physics-nuclear/src/activation.ts:15

chord function

function chord(b: Body, origin: Vec3, dir: Vec3, maxDistance: number): { enter: number; length: number } | null

Length of the chord a ray cuts through a body, from the point it enters, m (planes have no thickness here).

packages/physics-nuclear/src/radiation.ts:62

doseRate function

function doseRate( inventory: Inventory, r: number, layers: Layer[], shields: ShieldLibrary, coefficients: Record<RadiationKind, number> = EXAMPLE_DOSE_COEFFICIENTS, ): Record<RadiationKind, number>

Dose rate (Sv/s) of a source at a point through the given layers, by kind.

packages/physics-nuclear/src/radiation.ts:121

expm function

function expm(A: number[][]): number[][]

exp of a small dense matrix by scaling and squaring

packages/physics-nuclear/src/decay.ts:84

inhourRoot function

function inhourRoot(rho: number, generation: number, groups = DELAYED_GROUPS): number

The stable period of the point-kinetics model for a reactivity step: the largest root ω of the inhour equation ρ = Λω + Σ βᵢω/(ω+λᵢ).

packages/physics-nuclear/src/reactor.ts:236

layersBetween function

function layersBetween(host: PhysicsHost, from: Vec3, to: Vec3, shieldOf: (b: Body) => string | undefined, except: Body[] = []): Layer[]

The layers a ray crosses between two points: every body in the way, by the shield material its physics material names, plus the air between. except bodies (the source and the receiver themselves) are not counted.

packages/physics-nuclear/src/radiation.ts:91

nuclear function

function nuclear(isotopes = new IsotopeLibrary(), shields = new ShieldLibrary()): NuclearCapability

packages/physics-nuclear/src/index.ts:69

poisson function

function poisson(mean: number, rand: () => number): number

A count drawn from the Poisson law (Knuth for small means, the normal approximation above 50).

packages/physics-nuclear/src/decay.ts:71

rng function

function rng(seed: number)

Deterministic seeded stream (mulberry32).

packages/physics-nuclear/src/decay.ts:65

solve function

function solve(A: number[][], b: number[]): number[]

Solve A·x = b by Gaussian elimination with partial pivoting.

packages/physics-nuclear/src/reactor.ts:222

totalOf function

function totalOf: (r: Record<RadiationKind, number>) => number

packages/physics-nuclear/src/radiation.ts:137

wayWigner function

function wayWigner(tau: number, top = Infinity): number

Way–Wigner: fraction of the operating power left as decay heat τ seconds after shutdown from top seconds of operation.

packages/physics-nuclear/src/reactor.ts:16

AssemblyEntry interface

interface AssemblyEntry extends Placed

packages/physics-nuclear/src/index.ts:46

AssemblyEvent interface

interface AssemblyEvent

packages/physics-nuclear/src/assembly.ts:32

AssemblySpec interface

interface AssemblySpec

packages/physics-nuclear/src/assembly.ts:11

Capture interface

interface Capture

A capture that makes a radioactive nucleus: the stable from takes a neutron and becomes to, with a cross-section in barns (thermal Co-59: 37, Na-23: 0.53).

packages/physics-nuclear/src/activation.ts:7

DecayResult interface

interface DecayResult

packages/physics-nuclear/src/decay.ts:98

IsotopeDef interface

interface IsotopeDef

packages/physics-nuclear/src/decay.ts:10

Layer interface

interface Layer

packages/physics-nuclear/src/radiation.ts:33

NuclearCapability interface

interface NuclearCapability extends Capability

packages/physics-nuclear/src/index.ts:48

ReactorEntry interface

interface ReactorEntry extends Placed

packages/physics-nuclear/src/index.ts:45

ReactorEvent interface

interface ReactorEvent

packages/physics-nuclear/src/reactor.ts:82

ReactorSpec interface

interface ReactorSpec

packages/physics-nuclear/src/reactor.ts:38

ReceiverEntry interface

interface ReceiverEntry extends Placed

packages/physics-nuclear/src/index.ts:34

ShieldMaterial interface

interface ShieldMaterial

Radiation transport, lumped: a point source gives a fluence that falls as 1/(4πr²); each material along the ray takes a part of it away by its half-value layer; a dose coefficient turns the fluence into a dose. Alphas stop by range, not by a half-value layer.

packages/physics-nuclear/src/radiation.ts:9

SourceDef interface

interface SourceDef

packages/physics-nuclear/src/radiation.ts:113

SourceEntry interface

interface SourceEntry extends Placed

packages/physics-nuclear/src/index.ts:33

RadiationKind type

type RadiationKind = 'alpha' | 'beta' | 'gamma' | 'neutron'

packages/physics-nuclear/src/decay.ts:8

BARN const

const BARN: 1e-28

1 barn in m².

packages/physics-nuclear/src/activation.ts:4

DECAY_FRACTION const

const DECAY_FRACTION: number

the steady share of the fission energy that comes out later as decay heat

packages/physics-nuclear/src/reactor.ts:36

DELAYED_GROUPS const

const DELAYED_GROUPS: { beta: number[]; lambda: number[]; }

Standard thermal-fission delayed groups: fractions and decay constants (1/s).

packages/physics-nuclear/src/reactor.ts:10

E_FISSION const

const E_FISSION: 3.2e-11

A lumped power reactor: point kinetics with six delayed-neutron groups, reactivity from the rods and from the temperatures of the fuel and the coolant, a two-lump thermal model, and the decay heat of the fission products. Everything is data; there is no geometry.

packages/physics-nuclear/src/reactor.ts:7

EXAMPLE_DOSE_COEFFICIENTS const

const EXAMPLE_DOSE_COEFFICIENTS: Record<RadiationKind, number>

Sv·m² per particle that crosses a square metre (fluence-to-dose, order of magnitude for ~1 MeV).

packages/physics-nuclear/src/radiation.ts:31

EXAMPLE_ISOTOPES const

const EXAMPLE_ISOTOPES: Record<string, IsotopeDef>

A few real isotopes with their well-known half-lives, as sample data; a game writes its own.

packages/physics-nuclear/src/decay.ts:29

EXAMPLE_SHIELDS const

const EXAMPLE_SHIELDS: Record<string, ShieldMaterial>

Textbook values for roughly 1 MeV photons and fast neutrons (as sample data).

packages/physics-nuclear/src/radiation.ts:19

FISSION_ENERGY_PER_KG const

const FISSION_ENERGY_PER_KG: number

A runaway assembly in the one-group, lumped sense: the multiplication k follows from the mass against a critical mass the game supplies (with a reflector factor and a compression), the fission rate grows on the generation time as dF/dt = (k − 1)/Λ · F + S, and the assembly comes apart as it heats, which ends the reaction. This is a model for a game's accident or device record, with the numbers in the data; it has no geometry and is too coarse to be a design tool.

packages/physics-nuclear/src/assembly.ts:9

MEV const

const MEV: 1.602176634e-13

Radioactive decay: isotopes with half-lives and daughters, an inventory that decays exactly (the matrix exponential of the decay network, so a chain of any length closes), the heat the decays leave in the matter, and a seeded Poisson stream for counters.

packages/physics-nuclear/src/decay.ts:5

NUCLEAR_DEFAULTS const

const NUCLEAR_DEFAULTS: { doseStep: number; }

nuclear processes. Inventories of isotopes decay with the world (the heat goes to H when the carrier has a temperature), dose accumulates in receivers through the shielding the scene puts in the way, reactors run on point kinetics with feedback and decay heat, and a runaway assembly ends in an energy that is handed to X as a blast.

values (each at world / level / zone / entity scope):

  doseStep    dose between two `radiation:dose` events, Sv   (1e-3)

events: decay { source, decays }, radiation:dose { receiver, dose }, radiation:counts { receiver, n },

        `reactor:scram` / `reactor:prompt` / `reactor:melt` { name }, `assembly:critical` { name }, `assembly:disassembled` { name, energy, tnt }.

packages/physics-nuclear/src/index.ts:30

Sv_PER_MSV const

const Sv_PER_MSV: 0.001

packages/physics-nuclear/src/radiation.ts:138

YEAR const

const YEAR: number

packages/physics-nuclear/src/decay.ts:6