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Product

instrumentation cable seriesInconel 600 / 316L MIMS+600 °C to +1,000 °C≥ 10¹² Ω·m · 10¹⁰ Gy Immune

MI Coaxial Signal CableInconel 600 / AISI 304L MgO/SiO₂ mineral-insulated coaxial neutron & RF signal cable

MI Coaxial Signal Cable (Mineral-Insulated Metal-Sheathed, MIMS) engineered with an Inconel 600 or AISI 304L/316L seamless tubular sheath, high-purity compacted MgO or SiO₂ mineral dielectric (≥ 10¹² Ω·m), and copper, nickel or.

+1,000 °C Zero Organic
IEC 60702 / ASTM E844
Seamless Welded Tube
25 MPa Reactor Coolant
Order designation
MI-COAX-3.58-304L (.141")
Outer Ø
3.58 mm
Weight ≈
58 kg/km
Capacitance
92 pF/m
AC Test Voltage
1,800 V AC
All sizes (6)
Request a quoteDatasheetWhatsApp
Engineering reply in 2 business hoursCut-to-length export drumsEN 10204 3.1 certificate per drum
Outer sheath
Inconel 600 / 30
Seamless drawn metal tube
Dielectric
99.4 % MgO / SiO
High-density compacted oxide
Insul. resist.
≥ 10¹² Ω·m
≥ 10⁸ Ω·m @ +600 °C
Max. temp.
+600 to +1,000 °
Zero organic outgassing
Outer diameter
1.0 to 6.35 mm
0.040" to 0.250" MIMS ODs
Radiation dose
> 10¹⁰ Gy
In-core neutron & gamma immune

Typical values for this cable type, based on IEC 60702-1 / ASTM E844 / IEEE 323 — confirmed in the datasheet and quotation for your order.

Application fit

Is MI Coaxial Signal Cable right for your machine?

Built for extreme environments where every polymer or fluoropolymer decomposes: nuclear reactor pressure vessels (RPV), ex-core/in-core neutron detectors, fusion tokamak vacuum vessels and +800 °C gas-turbine combustion dynamics.

Furnace, kiln & high-temp zone

Suitable

100 % inorganic metal-and-ceramic construction operates continuously at +600 °C (and up to +1,000 °C peak).

Fixed installation

Suitable

Can be cold-formed to a 3 × OD bend radius and brazed or laser-welded directly into reactor pressure penetrations.

Immersion & wet locations

Suitable

Seamless cold-drawn Inconel 600 or 316L sheath withstands 25 MPa (3,600 psi) primary PWR coolant water.

Energy chain / drag chain

Not suitable

Solid annealed metal-tube cable for fixed installation; not for repetitive dynamic drag chains.

Use PUR-HF Drag-Chain Cable
Typical machinesNuclear In-Core & Ex-Core Neutron Flux DetectorsTokamak / Fusion Vacuum-Vessel RF & Magnetic ProbesAero-Derivative Gas Turbine Dynamic Pressure (Piezo)Liquid-Sodium / Molten-Salt Fast Reactor SensorsHigh-Energy Particle Accelerator Beamline Monitors

Construction

Layer by layer

MI Coaxial Signal Cable showing solid OFHC copper, copper-clad steel or Inconel/Ni centre conductor, high-density swaged MgO or SiO₂ ceramic powder insulation, and seamless annealed Inconel 600 or AISI 304L/316L outer metal sheath.

123
Schematic, not to scale — generated from the layer data
#LayerMaterial & reference
1Solid metal centre conductor (Cu / Ni / Inconel)Solid OFHC copper (low RF loss), Nickel 200, AISI 304L or Inconel 600 centre rodMatched thermal expansion with sheath across -269 °C to +800 °C
2High-purity compacted MgO or SiO₂ mineral dielectricNuclear-grade ≥ 99.4 % Magnesium Oxide (MgO, low boron/cobalt) or low-loss Silicon Dioxide (SiO₂) compacted to > 75 % theoretical densityProvides ≥ 10¹² Ω·m volume resistivity and controlled 50 Ω impedance
3Seamless drawn Inconel 600 or AISI 304L/316L metal sheathSeamless cold-drawn, bright-annealed Alloy 600 (Inconel 600, UNS N06600) or low-cobalt AISI 304L/316L tube100 % hermetic helium leak-tight (< 10⁻⁹ mbar·L/s) & 25 MPa pressure rated

MI-COAX-INC600 (1.5 / 3.0 / 4.76 / 6.35 mm)

Inconel 600 sheath + 99.4 % MgO + Ni/Inconel core for PWR/BWR neutron flux detectors

MI-COAX-316L-50R (2.2 / 3.58 / 6.35 mm RF)

50 Ω low-loss SiO₂/MgO + OFHC copper core + 304L/316L sheath for fusion RF & turbine piezo probes

Technical data

Ratings & operating limits

Typical values: Typical values for this cable type, based on IEC 60702-1 / ASTM E844 / IEEE 323. Values for your order are confirmed in the datasheet and quotation.

Electrical

Characteristic impedance
50 ± 3 Ω (or high-Z low-capacitance charge-transfer geometries)
Insulation resistivity
≥ 10¹² Ω·m (@ 20 °C) · ≥ 10⁸ Ω·m (@ +600 °C)
Capacitance @ 1 kHz
95 to 155 pF/m (50 Ω MgO) · 75 to 110 pF/m (SiO₂)
Dielectric breakdown
1,000 V to 2,500 V AC rms (depending on outer diameter)

Thermal

Continuous operating temp.
-269 °C (4 K) to +600 °C (up to +1,000 °C for Inconel 600)
Thermal shock resistance
Quench from +600 °C to +20 °C water without sheath cracking
Vacuum outgassing
Zero organic volatiles; UHV bakeable to +600 °C (< 10⁻¹¹ mbar)

Mechanical

Min. bend radius
3 × OD (annealed cold-forming) · 5 × OD (repeated re-bending)
External pressure rating
Up to 25 MPa (250 bar) at +350 °C (PWR primary loop)
Helium leak tightness
< 1 × 10⁻⁹ mbar·L/s (100 % mass-spectrometer tested)

Resistance

Neutron & gamma fluence
> 10¹⁰ Gy gamma and > 10²² n/cm² thermal/fast neutron fluence
Low cobalt impurity
Co ≤ 0.05 % (500 ppm) option to minimize ⁶⁰Co activation
Fire behaviour
100 % non-combustible (A1 inorganic metal + oxide)

Reference standards

Nuclear MIMS standard
ASTM E844 & IEC 60702-1 / IEC 61515
Nuclear QA program
ISO 19443 / ASME NQA-1 / RCC-E
RoHS & REACH
2011/65/EU & EC 1907/2006 compliant

Identification

Outer surface
Bright annealed seamless metallic finish (Inconel 600 or 304L/316L)
Customs tariff (HS)
8544.2000
End sealing
Delivered with laser-welded or epoxy-potted moisture-proof end seals

Sizes

6 standard MI Coaxial Signal Cable configurations

Outer diameter, sheath/conductor metallurgy, characteristic impedance, capacitance and voltage rating.

Dimensions & dielectric parameters
Order designationSheath / Dielectric / CoreOuter Ø
mm		Weight ≈
kg/km		Capacitance
pF/m		Test V
V AC		Enquiry
Mineral-Insulated Metal-Sheathed (MIMS) Coaxial Cables
MI-COAX-1.5-INCInconel 600 / MgO / Inconel 6001.50111501,000
MI-COAX-2.2-316LAISI 316L / SiO₂ / OFHC Cu (50 Ω)2.2022951,200
MI-COAX-3.0-INCInconel 600 / MgO / Nickel 2003.00421351,500
MI-COAX-3.58-304L (.141")AISI 304L / SiO₂ / OFHC Cu (50 Ω)3.5858921,800
MI-COAX-4.76-INC (.188")Inconel 600 / MgO / OFHC Cu (50 Ω)4.761021252,000
MI-COAX-6.35-INC (.250")Inconel 600 / MgO / OFHC Cu (50 Ω)6.351781202,500
  • Typical values for this cable type; dimensions and weights for your order are confirmed in the quotation.
  • Can be supplied as bulk hermetically sealed coils or terminated with ceramic-to-metal HN, BNC, SMA or triaxial nuclear connectors.

Quality & approvals

Testing & inspection

Routine tests on every production length, sample and type tests per batch — documented on an EN 10204 3.1 inspection certificate.

  1. ConductorClass 5 stranding
  2. Spark test100 % in-line
  3. Lay-upCores, earth, fillers
  4. SheathingInner, braid / screen, outer
  5. Electrical testsAC voltage, resistance
  6. DimensionsOD, wall thickness
  7. Inspection documents & dispatchDrum & dispatch
Testing & inspectionTest value / referenceFrequency
Routine tests
100 % insulation resistance (@ 500 V DC), AC hi-pot & TDR sweepIR ≥ 10¹² Ω·m @ 20 °C and zero dielectric breakdownEvery manufactured coil
100 % Helium mass-spectrometer & nitrogen pressure leak testLeak rate < 1 × 10⁻⁹ mbar·L/s over entire seamless tubeEvery manufactured coil
Sample tests
+600 °C high-temperature insulation resistivity & breakdown testMaintains ≥ 10⁸ Ω·m volume resistivity at +600 °CPer production lot

Inspection certificate

Issued with every drum, listing the routine test results for that length.

Product approvals

ASTM E844 Nuclear MIMSIEC 60702-1 CompliantISO 19443 / ASME NQA-1 QA

Company certificates

ISO 9001ISO 14001ISO 45001VDE marks approvalUL / cULCE · LVD / EMC

Marking & supply

Ordering & delivery

Sheath marking

Laser-etched tag: TEBAOFLEX MI-COAX INCONEL 600 / MgO ASTM E844
Delivery form
Fumigated wooden drums, steel reels or precision spools
Standard lengths
500 m · 1000 m (or custom cut/spooled lengths)
MOQ
100 m (standard) · 500 m (custom)
Lead time
2–4 weeks ex-works
Incoterms
EXW, FOB, CIF, DAP

Technical documents

Downloads

PDFMI Coaxial Signal Cable – technical datasheet6 sizes · construction, technical data, approvalsXLSXMI Coaxial Signal Cable spec data (Excel)All 6 sizes with dimensions and data, for your BOM or quotation
Revision
2026-10-20
Updated
2026-10-20

FAQ

Questions engineers ask first

Not covered here? Send your drawing — an engineer replies within 2 business hours.

Why must MgO mineral insulation be hermetically sealed immediately after cutting?
Compacted Magnesium Oxide (MgO) powder is hygroscopic: if exposed to ambient air moisture, water molecules adsorb onto the oxide grain boundaries and lower the insulation resistance by several orders of magnitude. All coils are baked above +400 °C under vacuum and shipped with welded or glass-ceramic hermetic end seals.
When should we choose SiO₂ (Silicon Dioxide) dielectric instead of MgO?
High-purity MgO provides the highest thermal conductivity and mechanical crush strength for neutron detectors up to +1,000 °C. Fused SiO₂ has a lower dielectric constant (εr ≈ 2.2 vs ~3.6 for compacted MgO) and lower microwave loss tangent, making it ideal for 50 Ω RF reflectometry and plasma diagnostics in fusion tokamaks.
When do we need MI Triaxial Signal Cable instead of MI Coaxial Signal Cable?
Use MI Coaxial for pulse-mode counting, RF probes and general high-temperature signals. For DC/Campbell-mode fission chambers and micro-picoamp in-core detectors where guard-ring leakage cancellation and triboelectric noise suppression are required, specify MI Triaxial Signal Cable.
Why is low-cobalt (< 0.05 % Co) Inconel 600 or 304L specified for nuclear reactors?
Natural cobalt-59 absorbs thermal neutrons to become radioactive Cobalt-60 (5.27-year half-life, intense gamma emitter). Restricting residual cobalt below 500 ppm prevents the cable sheath from becoming a major radiation dose source during refueling outages.

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