INDUSTRY COMPONENT

Guide Thimble

A precision guide thimble component for nuclear fuel assembly positioning and alignment in reactor cores.

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Component Specifications

Definition
A cylindrical guide thimble is a critical structural component in nuclear fuel assemblies, designed to maintain precise spacing and alignment between fuel rods while providing channels for control rod insertion and instrumentation. It ensures geometric stability under extreme thermal, hydraulic, and radiation conditions during reactor operation.
Working Principle
The guide thimble functions as a rigid tubular guide that maintains fuel rod lattice geometry through mechanical constraint, allowing control rods to move freely within its bore while withstanding axial and lateral loads from coolant flow and thermal expansion.
Materials
Zirconium alloy (typically Zircaloy-4 or ZIRLO), austenitic stainless steel (304L, 316L), or nickel-based alloys (Inconel 718), selected for low neutron absorption, corrosion resistance, and high-temperature mechanical properties.
Technical Parameters
  • Length 4000-5000 mm
  • Outer Diameter 12.0-15.0 mm
  • Surface Finish Ra ≤0.8 μm
  • Wall Thickness 0.4-0.8 mm
  • Pressure Rating 15-20 MPa
  • Operating Temperature Up to 350°C
  • Straightness Tolerance ≤0.1 mm/m
Standards
ISO 18279, ASTM B353, RCC-M

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Guide Thimble.

nuclear guide thimble fuel assembly component zirconium alloy tube control rod guide reactor core alignment nuclear fuel hardware Guide Thimble Guide Thimble in Machinery and Equipment Manufacturing

Parent Products

This component is used in the following industrial products

Fuel Assembly

A structural unit containing nuclear fuel rods arranged in a specific geometric pattern for controlled fission reactions.

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Engineering Analysis

Risks & Mitigation
  • Stress corrosion cracking
  • Grid-to-rod fretting wear
  • Dimensional deformation under irradiation
  • Hydride embrittlement in zirconium alloys
FMEA Triads
Trigger: Inadequate material purity or improper heat treatment
Failure: Premature corrosion or cracking
Mitigation: Strict material certification, non-destructive testing (UT, ET), and compliance with nuclear-grade standards.
Trigger: Excessive vibration or flow-induced oscillation
Failure: Fretting wear at spacer grid contact points
Mitigation: Optimized support design, anti-vibration features, and wear-resistant coatings.

Industrial Ecosystem

Compatible With

Interchangeable Parts

Compliance & Inspection

Tolerance
±0.05 mm on critical dimensions, per ASME Y14.5
Test Method
Dimensional inspection (CMM), hydrostatic pressure testing, eddy current testing for defects, and neutron absorption cross-section verification.

Buyer Feedback

★★★★☆ 4.6 / 5.0 (36 reviews)

"Reliable performance in harsh Machinery and Equipment Manufacturing environments. No issues with the Guide Thimble so far."

"Testing the Guide Thimble now; the technical reliability results are within 1% of the laboratory datasheet."

"Impressive build quality. Especially the technical reliability is very stable during long-term operation."

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Frequently Asked Questions

What is the primary function of a guide thimble in a fuel assembly?

It maintains precise fuel rod spacing, provides channels for control rods and instrumentation, and ensures structural stability under reactor operating conditions.

Why are zirconium alloys commonly used for guide thimbles?

Zirconium alloys offer low neutron absorption, excellent corrosion resistance in high-temperature water, and good mechanical strength, making them ideal for nuclear applications.

Can I contact factories directly?

Yes, each factory profile provides direct contact information.

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