Radiation Zone Classification & Shielding Design Engine

A computational framework for automated radiological zoning and civil engineering shielding mitigation in high-energy physics facilities.

1. Overview

This project bridges the gap between dosimetric survey data and civil infrastructure management. In high-energy physics environments (accelerator tunnels) and environmental remediation sites, translating detector readings into structural shielding requirements is often a manual, iterative process.

This framework automates the workflow by:

1. Context-Aware Interpolation: Utilizing Inverse Distance Weighting (IDW) and Clough-Tocher scheme for point-source hotspots (mimicking $1/r^2$ physics) and Linear Barycentric Triangulation for long-geometry accelerator tunnels.
2. Regulatory Compliance: Auto-classifying zones based on CERN Safety Code F and IAEA Basic Safety Standards.
3. Shielding Remediation: Calculating the required physical barrier thickness ($x$) for concrete, steel, lead, high-density polyethylene (HDPE) and materials like Bentonite Slurry or Compacted Earth/Soil ($\rho$ = 1.80) using a deterministic Linear Attenuation Model.

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2. Key Features

• Multi-Model Interpolation:
  • IDW (Inverse Distance Weighting): Deterministic hotspot mapping for beam targets and scattered sources.
  • Linear/Barycentric: Artifact-free mapping for long tunnels and corridors (prevents "overshooting" negative values).
  • Clough-Tocher (Cubic): $C^1$ continuous surface reconstruction for visualizing smooth dose gradients and soft transitions in dense survey datasets.
• Dynamic Zoning: Instantly segments areas into Public, Supervised, Controlled, and Restricted zones.
• Deterministic Shielding: Solves the Beer-Lambert Law for identified hotspots to determine necessary wall thickness.
• Extended Material Library: Includes attenuation coefficients ($\mu$) for:
  • Standard Concrete ($\rho=2.35$)
  • Heavy Concrete (Barite)
  • Steel & Lead
  • Bentonite Slurry (Low-cost geocomposite)
  • Borated Bentonite
  • HDPE (Neutron moderation benchmark)
  • Earth or soil ($\rho$ = 1.80)

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3. Validation Scenarios

To ensure robustness, the engine was stress-tested against two distinct radiological topologies:

Case A: LHC Accelerator Tunnel (Simulated)

• Topology: Linear geometry (50m length).
• Method: Linear Interpolation.
• Objective: Map dose gradients along a beamline without generating artificial "ringing" or negative dose artifacts common in cubic spline methods.
• Result: Successfully identified the Supervised Area boundary at 35m from the beam dump with 0% interpolation overshoot.

Fig 1. Interpolated dose map of a tunnel segment showing zone classification contours. Source intensities scaled for demonstration; full-facility modeling requires Monte Carlo transport codes.

Case B: Chernobyl Exclusion Zone

• Topology: Scattered environmental hotspots.
• Method: Inverse Distance Weighting (IDW) ($p=2$, k-Nearest Neighbors).
• Objective: Resolve discrete contamination points in a high-noise environment.
• Result: Correctly isolated 3 distinct hotspots ($> 25 \mu\text{Sv/h}$) and generated a "Restricted" zone contour map consistent with $1/r^2$ decay physics.

Fig 2. Interpolated dose map of Chernobyl Exclusion Zone showing zone classification contours.

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4. Theoretical Framework

Zone Classification Standards

Classification logic is derived from CERN Safety Code F thresholds assuming 2000 hours occupancy per year under normal working conditions (Configurable):

Zone	Dose Rate ($\mu Sv/h$)	Engineering Controls Required
🟢 Public	$< 0.5$	None
🟡 Supervised	$0.5 - 3.0$	Radiological Monitoring
🟠 Controlled	$3.0 - 10.0$	Dosimetry, Access Control
🔴 Restricted	$> 10.0$	Physical Barriers / Interlocks

Physics Engine: IDW Interpolation

For source-dominated environments, we utilize Inverse Distance Weighting to preserve physical accuracy:

$$ Z(x) = \frac{\sum w_i z_i}{\sum w_i}, \quad w_i = \frac{1}{d(x, x_i)^p} $$

Where $p=2$ represents the Inverse Square Law inherent to photon radiation.

Shielding Design Logic

For grid cells classified as Restricted, the system computes the minimum shielding thickness ($x$) using the inverted Beer-Lambert Law:

$$ x = -\frac{\ln(I_{target} / I_{source})}{\mu(E)} $$

Where $\mu(E)$ is the energy-dependent linear attenuation coefficient sourced from NIST XCOM at 1.0 MeV.

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5. Usage

Interactive Demo

The easiest way to explore the engine is through the live web application:

Launch Interactive Dashboard

Local Installation

For users who wish to run the code locally

Prerequisites

• Python 3.8+
• SciPy (Spatial interpolation: cdist, griddata, cKDTree)
• Pandas (Data manipulation)
• Streamlit (Visualization Dashboard)

Installation & Execution

# 1. Clone the repository
git clone https://github.com/aw920h/radiation-mapper.git

# 2. Install dependencies
pip install -r requirements.txt

# 3. Run the analysis engine (Generates Maps & Reports)
python radiation_mapper.py

# 4. Launch the Interactive Dashboard
streamlit run app.py

Sample Output (Compliance Report)

[ALERT] RESTRICTED ZONE DETECTED AT [X: 25.0m, Y: 15.0m]
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INPUT METRICS:
  Source Intensity:  100.9 µSv/hr (Beamline Hotspot)
  Target Threshold:  0.5 µSv/hr (Public Limit)
  Photon Energy:     1.0 MeV

REMEDIATION OPTIONS (THICKNESS REQUIRED):
  > Ordinary Concrete:  35.39 cm
  > Steel:              17.69 cm
  > Lead:               9.65 cm
  > Bentonite Slurry:   52.12 cm (Cost-effective option)

RECOMMENDATION:
  Deploy 40cm reinforced concrete wall or restricted access gate.

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6. References & Standards

This software implements standards defined in the following regulatory and technical frameworks:

1. CERN HSE Unit. (2006). CERN Safety Code F: Radiation Protection. EDMS 335729
2. IAEA. (2014). Radiation Protection and Safety of Radiation Sources: International Basic Safety Standards (GSR Part 3). Vienna: IAEA.
3. NIST. (2010). XCOM: Photon Cross Sections Database. National Institute of Standards and Technology.
4. Shepard, D. (1968). A two-dimensional interpolation function for irregularly-spaced data. Proceedings of the 1968 23rd ACM National Conference. (Basis for IDW).

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Disclaimer: This tool is a computational aid for preliminary design and research. Final shielding verification must be conducted via Monte Carlo transport codes (FLUKA/Geant4) and approved by a certified Radiation Protection Officer.