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REACTOR SYSTEMS DESIGNER

SPACECRAFT FISSION & FUSION — SHADOW SHIELDING & DOSE ESTIMATOR v4.1

READY
▼Reactor TypeHWR
HWRHeat Pipe, passive
GAS COREHe/CO₂, high-temp
LIQ. METALLi/NaK, dense
PIN COREUN wire, compact
PART. BEDTRISO, NERVA-class
SNAP-TYPEFlight-proven
SALT (MSR)Molten salt, liquid
— FUSION (SPECULATIVE) —
D-T14 MeV neutrons
D-He3Low-neutron fusion
p-B11Near-aneutronic
—
▼Power & Scale500 kWt / 25%
Thermal Power500 kWt
Logarithmic scale: 10 kWt → 5 GWt. High-power reactors need proportionally thicker shielding or greater crew standoff.
Conversion Efficiency25%
Thermal cycles: 5–45%. Direct energy conversion (D-He3, p-B11, projected): up to ~70–80%.
Source Term UncertaintyNominal
Source terms are empirical, not from neutronics. Multiply to bracket uncertainty.
▼Geometry & Crew50 m · r=3 m
Reactor → Crew Habitat Front50 m
All distances measured from reactor. Dose evaluated at habitat front (nearest point). Shadow coverage checked at rear (limiting point).
Crew Habitat Depth (axial)10 m
Crew Habitat Radius3.0 m
Shadow Safety Margin1.2×
Required shadow radius = habitat radius × margin. Accounts for alignment error, boom flex, finite source size.
▼γ / X-Ray ShieldPb 25cm @1.5m
▸ PRIMARY MATERIAL
LEAD (Pb)Dense, classic, cheap
TUNGSTEN (W)Densest, high-temp
TANTALUM (Ta)Ductile, high-temp
DEPLETED UBest HVL, regulated
W-POLYMERDual γ+n function
BORATED STEELStructural shield
STEELStructural only
Primary Thickness25 cm
▸ BORATED POLYMER LAYER
Always included. Outward-facing B₄C/HDPE layer captures thermal neutrons via ¹⁰B(n,α) and suppresses low-energy capture gammas. Positioned as a separate layer in the stack at its own position.
BP Layer Thickness15 cm
BP Layer Position (from reactor)3.0 m
Shield Diameter1.5 m
Position from Reactor1.5 m
▼Neutron ShieldLiH 80cm @2.5m
▸ MATERIAL
LiHClassic, space heritage
ZrH₂Best vol. efficiency
TiH₂Dense hydride
B₄CStructural, hard
BNHigh-temp stable
B₄C+PEBorated poly
WATER/ICEShadow tank
Be+B₄CReflect+absorb
LH₂ TANKNTR free shielding
Thickness80 cm
1–1000 cm. High-power reactors (MW–GW) need very thick neutron shields or large standoff distance. Large values model water-ice shadow tanks.
Shield Diameter1.5 m
Position from Reactor2.5 m
▼Mission EnvironmentDeep space cruise
Mission Profile
Mission Duration1.0 yr
GCR added to reactor contribution for total mission dose budget. SPE (design reference 250 mSv/event) shown separately. These are reference values, not model outputs.
POWER OUTPUTS
SHADOW GEOMETRY — PASS/FAIL
THERMAL MANAGEMENT
REACTOR CONTRIBUTION — ANNUAL DOSE ESTIMATE
REACTOR DOSE (reactor contribution only — uncertainty band shown)—
TOTAL MISSION DOSE BUDGET (rough estimate)—
DOSE BREAKDOWN BY SOURCE
SOURCETYPENOMINALRANGE (optimistic–worst)NOTE
SHADOW CONE ANALYSIS — REQUIRED vs ACTUAL SHIELD DIAMETER
DOSE PROFILE ALONG HABITAT AXIS
LOCATIONDISTANCENOMINAL DOSECONE COVERAGESTATUS
LAYER STACK (sorted by position)
SCHEMATIC — NOT TO SCALE
Reactor at left — crew habitat at right
REACTOR CORE DIMENSIONS
SHIELD MASS ESTIMATES