Domain: Radiological Protection & Health Physics
Expert Persona: Senior Radiological Safety Officer (RSO) / Nuclear Health Physicist
Vocabulary/Tone: Technical, clinical, focus on dosimetry, flux, and radiological hazard assessment.
Reviewer Group Recommendation
The most appropriate group to review this material would be Environmental Remediation Engineers and Radiological Protection Professionals. This group focuses on the identification, measurement, and containment of Legacy Radiological Sites (LRS) and the assessment of public exposure risks in abandoned industrial zones.
Summary Report
Abstract:
This field report documents a radiological survey conducted at the South Terras Mine in Cornwall, identified as a significant legacy uranium and radium production site. Utilizing a portable scintillation detector (Radiacode), the surveyor transitioned from an ambient background of 10–12 counts per second (CPS) to high-flux environments. Findings indicate significant radiological contamination in the vicinity of abandoned structures and mine tailings. Dose rates escalated from nominal levels to approximately 17.14 μSv/h before the instrument transitioned into Kilo Counts Per Second (KCPS) mode, recording a peak flux of 1.44 KCPS. The data confirms the presence of concentrated NORM (Naturally Occurring Radioactive Material) and suggests a substantial localized radiological burden.
Radiological Survey Findings & Site Assessment:
00:00:21 Site Context: The location is identified as South Terras Mine, Cornwall, a historical site that transitioned from tin extraction to uranium and radium mining in the late 19th century until its closure in the 1930s.
00:00:43 Baseline Dosimetry: Initial ambient readings distal to the site recorded a background flux of 10–12 CPS. Background dose rates were initially characterized as within normal limits for the region.
00:01:16 Initial Flux Increase: As the surveyor approached the mine perimeter, a rapid increase in ionization events was recorded, climbing from baseline to over 230 CPS.
00:01:50 Proximity to Residential Ruins: Ambient dose equivalent rates reached 17.14 μSv/h near an abandoned residence. This represents a significant elevation above typical terrestrial background radiation, suggesting the use of radioactive mine spoil in local construction or significant proximity to tailings.
00:02:48 Transition to High-Intensity Zone: Moving along the primary access track toward the mine workings, the detector recorded a sharp incline in counts, surpassing 900 CPS and approaching instrument saturation for the standard scale.
00:03:53 Instrument Scale Shift (KCPS): The radiological flux reached a density where individual pulse discrimination required the device to switch from CPS to KCPS (Kilo Counts Per Second). This indicates a transition from scattered contamination to high-activity source material.
00:04:17 Peak Observed Activity: The survey recorded a maximum flux of 1.44 KCPS (1,440 counts per second). At this juncture, the surveyor determined the radiological risk necessitated immediate egress from the hotspot to limit integrated dose uptake.
Key Takeaway: The South Terras Mine remains a highly active radiological anomaly. The presence of counts in the KCPS range indicates that significant quantities of uranium-series daughter products remain un-remediated on the surface, posing a distinct external exposure hazard to unauthorized personnel.