FD218 Alpha-Spectrum Radon Measurement System

Overview

The FD218 Alpha-Spectrum Radon Measurement System is a field-deployable, high-resolution alpha spectrometry instrument engineered for quantitative radon-222 (²²²Rn) and thoron-220 (²²⁰Rn) activity concentration measurement in air, soil gas, water, and surface exhalation scenarios. It operates on the principle of electrostatic collection coupled with alpha-particle energy discrimination using a passivated implanted planar silicon (PIPS) detector. This method enables direct, isotope-specific identification and quantification of radon progeny decay events—primarily the 5.49 MeV alpha peak from ²¹⁸Po (daughter of ²²²Rn) and the 6.29 MeV peak from ²¹⁶Po (daughter of ²²⁰Rn)—with minimal spectral interference. The system is designed to meet rigorous metrological requirements for environmental radiation monitoring, occupational health assessments, and regulatory compliance in building diagnostics, geological surveys, and nuclear facility surveillance.

Key Features

• High-resolution PIPS detector with ultra-thin contact electrode: low electronic noise, mechanical robustness, and cleanable surface for long-term stability in variable field conditions
• Real-time alpha energy spectrum display and on-board peak identification algorithm for immediate qualitative and quantitative interpretation
• Four integrated measurement modes: ambient air radon, soil gas radon, waterborne radon (via degassing module, optional), and radon exhalation rate (optional accessory kit)
• Constant-flow active sampling pump with calibrated volumetric flow control (±2% accuracy), ensuring traceable gas volume integration
• Flexible operational protocols: single-point grab sampling, time-series continuous monitoring (1–240 min intervals), and spatial scanning mode for gradient profiling
• Compact form factor (276 × 246 × 283 mm) and lightweight design (3.8 kg host unit) optimized for handheld or tripod-mounted deployment
• Dual-power architecture: rechargeable Li-ion battery supporting >72 h continuous operation or AC mains input; no external power dependency in remote locations
• On-device data storage capacity: 10,000 complete measurement records including full spectral histograms, timestamped metadata, and environmental parameters (T, RH)

Sample Compatibility & Compliance

The FD218 supports standardized sampling protocols across multiple environmental matrices. For air, it complies with ISO 11665-2:2019 (Measurement of radon-222 in air — Part 2: Integrated measurement method for determining average activity concentration), ASTM D6932-22 (Standard Guide for Measurement of Radon in Soil Gas), and national standards GB 50325-2020 and GB/T 14582-93. Soil gas measurements adhere to EJ/T 605-2018 for uranium exploration contexts. Water analysis (optional) follows T/CECS 569-2019 methodology using closed-loop sparging and charcoal trap transfer. All configurations support GLP-aligned documentation: each measurement includes audit-trail metadata (operator ID, location GPS tag, calibration certificate ID, detector bias voltage, temperature/humidity logs). Optional traceable calibration is available via accredited laboratories—including the National Institute of Metrology (NIM, China) or the Nuclear Industry Radioactive Survey & Metrology Station—with certificates issued per JJG 825-2019.

Software & Data Management

The FD218 interfaces via USB 2.0 and Bluetooth 5.0 for secure, cable-free data export to Windows-based RadonView™ desktop software (v3.2+). Software features include spectral deconvolution with Poisson-constrained least-squares fitting, background subtraction using real-time continuum modeling, and uncertainty propagation per GUM (JCGM 100:2018). Export formats include CSV (for LIMS integration), PDF reports compliant with ISO/IEC 17025 documentation requirements, and PNG spectral images. Firmware updates are digitally signed and validated prior to installation. Data integrity safeguards include write-once memory partitioning, SHA-256 hash logging for all stored spectra, and optional 21 CFR Part 11-compliant user access controls (role-based login, electronic signatures, immutable audit trail).

Applications

• Indoor air quality assessment in residential, commercial, and institutional buildings per national radon action levels (e.g., 100 Bq/m³ in EU, 148 Bq/m³ in US EPA guidelines)
• Geological radon mapping for uranium prospecting, fault-line characterization, and volcanic activity monitoring
• Post-mitigation verification of radon reduction systems (sub-slab depressurization, sealing, ventilation upgrades)
• Regulatory compliance testing for construction materials, groundwater sources, and landfill cover performance
• Research-grade studies on radon progeny equilibrium ratios, diurnal variation, and seasonal transport dynamics in unsaturated zones
• Field validation of passive detector networks (CR-39, electret ion chambers) through co-located active reference measurements

FAQ

What radionuclides does the FD218 detect and distinguish?
It quantifies ²²²Rn and ²²⁰Rn independently via their characteristic alpha decay energies (5.49 MeV and 6.29 MeV, respectively) using PIPS detector spectral resolution of ≤25 keV FWHM.
Is calibration traceable to national standards?
Yes—optional factory calibration is performed against NIM-certified radon reference chambers (traceable to BIPM CIPM MRA), with certificate validity period of 12 months.
Can the instrument operate unattended for extended periods?
Yes—battery-powered continuous monitoring up to 72 h is supported; external 12 V DC input enables indefinite operation with solar/battery bank integration.
How is moisture handled during soil gas sampling?
An integrated Nafion™ membrane dryer (optional) removes water vapor prior to electrostatic collection, preventing detector contamination and spectral quenching.
Does the system support automated QA/QC routines?
Yes—built-in daily background check, energy calibration verification using internal ²⁴¹Am source (optional), and auto-diagnostic self-test on power-up.