Precision, Compliance, and Long-Term Performance
Concrete inside nuclear facilities is not typical structural concrete. It’s engineered for radiation shielding, extreme loads, and decades of thermal cycling. When defects appear, repairs must be precise, code-compliant, and fully documented to protect people, assets, and uptime.
At Bunney’s Inc., we deliver nuclear-grade concrete repair solutions for utilities and high-stakes industrial sites across Arizona and the Southwest—built on rigorous quality control and proven field execution.
New to Bunney’s? Learn who we are and explore our capabilities.
What Makes Nuclear-Grade Concrete Different?
Nuclear environments demand materials and methods that perform under exceptional conditions. Concrete here supports safety systems, shields personnel, and preserves structural integrity over long service lives.
Key performance requirements
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Low permeability: Limits moisture ingress and protects embedded steel.
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Radiation shielding: Dense mixes and aggregates reduce transmission.
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Thermal resistance: Handles severe temperature gradients and cycling.
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High compressive capacity: Carries massive static and dynamic loads.
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Standards compliance: Meets ACI 349, applicable ASTM standards, and NRC/IAEA guidance.
Typical applications
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Reactor containment and biological shielding
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Spent-fuel storage structures and cooling vaults
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Equipment/turbine foundations and pipe supports
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Safety-related structures in auxiliary buildings
Why Nuclear Concrete Deteriorates
Even well-designed concrete can suffer damage over time. Accurate diagnosis drives the right repair plan.
Primary mechanisms
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Thermal cycling: Expansion/contraction induces cracking.
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Radiation exposure: Gradual changes in cement paste microstructure.
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Alkali–silica reaction (ASR): Internal expansion and map cracking.
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Reinforcement corrosion: From water intrusion, chloride ingress, or carbonation.
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Mechanical/seismic loading: Fatigue, settlement, and stress concentrations.
Navigating Codes and Oversight
Nuclear concrete repairs are executed under a tightly controlled quality program.
Governing bodies & references
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NRC: U.S. oversight for nuclear safety and licensing
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ACI 349: Design/repair for nuclear safety-related concrete structures
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ASTM: Materials and test methods (e.g., sampling, compressive strength)
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IAEA: International safety and performance guidance
Compliance workflow
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Safety classification: Confirm safety-related vs. non-safety-related scope.
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Engineered repair design: Calculations, drawings, mix/mortar specs, procedures.
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Pre-qualification: Materials, mockups, and crew certifications with traceability.
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Regulatory coordination: Hold points, inspections, and documentation agreements.
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Execution with QA/QC: Batch tickets, cure logs, NDT, and field reports.
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Closeout: Engineer-of-record sign-off, as-builts, and records for audits/license renewal.
Need cross-discipline support? See our Mechanical Services.
Materials and Methods We Use
Selections are driven by engineering requirements, exposure conditions, and compatibility with existing substrates.
Commonly specified materials
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Low-shrinkage, high-bond repair mortars
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Structural epoxy injection resins for micro-/fine-crack sealing
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Fiber-reinforced polymer (FRP) systems for confinement/strengthening
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Corrosion-resistant reinforcement (stainless or epoxy-coated)
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Silica-fume or supplementary cementitious materials to reduce permeability
Typical techniques
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Surface preparation: Hydrodemolition or abrasive blasting to sound substrate
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Form-and-pour / pre-placed aggregate: For section replacement and volume rebuild
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Shotcrete (dry or wet): Access-constrained walls, vaults, and liners
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Crack repair: Epoxy injection with verification coring or UT where appropriate
All materials and procedures are pre-qualified and approved by the engineering team before use.
Testing, Inspection, and Certification
Every repair is verified to perform as designed—now and over time.
Verification program
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Nondestructive testing (NDT): Ultrasonic pulse velocity, GPR, acoustic emission
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Core sampling & lab testing: Compressive strength, bond, and petrography as needed
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Visual inspections & photo logs: Documented acceptance criteria
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Embedded sensors (where specified): Temperature, moisture, or strain monitoring
Closeout records
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Engineer-of-record approvals
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QA/QC packages: mix/batch tickets, cure logs, inspection reports
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As-built drawings and annotated repair maps
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Regulatory clearances aligned with NRC/owner requirements
Plan for Longevity
Repairs are most effective when tied to a broader asset management plan.
Lifecycle best practices
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Preventive maintenance and periodic condition assessments
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Digital models/digital twins to simulate aging mechanisms
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Condition-based monitoring to trigger targeted interventions
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Documentation aligned with license-extension milestones (up to 80 years)
For sustained coverage across sites and systems, explore our Industrial Maintenance Services.
Why Bunney’s Inc.
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Proven nuclear experience: Field execution under rigorous QA programs
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Certified teams: Safety-first culture, continuous training, and traceable procedures
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Arizona-based, Southwest-ready: Fast mobilization and familiarity with regional plants
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End-to-end delivery: Engineering collaboration, construction, testing, and compliant closeout
FAQs
What makes a repair “nuclear-grade”?
It follows engineered procedures, qualified materials, and a documented QA program that meets ACI/NRC/ASTM requirements for safety-related environments.
How do you decide between injection, patch, or replacement?
We evaluate defect type, structural demand, access, and lifecycle goals—then select the least intrusive method that restores design capacity and durability.
Can repairs occur during operations?
Many repairs can be staged during normal operations with appropriate controls; others are scheduled for outages. We plan around plant conditions and hold points.
How is success verified?
Through NDT, cylinders/cores, bond testing where specified, cure monitoring, and documented inspections—culminating in engineer-of-record sign-off.
Do you work outside Arizona?
Yes. While based in Goodyear, Arizona, we support utilities and industrial sites across the Southwest. Ask about current availability.
