Overview
The source term is defined as the types and quantity of radionuclides that encompass a known source and the potential for it to cause radiological exposure in a nuclear facility. It is an important part of the nuclear licensing process and it enables plant operators to minimize and manage the radiation dose to their workers.
As fission and activation products are produced in the reactor core and contamination moves around within components and systems, the source term characteristics may change and must be regularly measured and monitored.
Outage activity transport monitoring (OATM) provides the information needed to estimate the gamma-emitting radionuclides deposited on out-of-core components producing external gamma fields.
Our iSTM services include the provision of OATM surveys, source term factors analysis, sample analysis, and online monitoring.
Why Us?
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Reliable Results
Our knowledge of monitoring equipment and methodology, our quality-assured laboratories, and our radiation protection experience enable us to provide you with the reliable results that allow you to manage dose limits with precision.
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Systematic OATM Survey Methodology
The methodology we use for collecting and analyzing the radiation field and gamma spectral data in a systematic and consistent way across the CANDU fleet is recognized and outlined in the COG guideline.
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Backed with an In-house Laboratory
Contaminated specimens are analyzed in our radioactive laboratory enabling us to identify the radioisotope composition of crud and magnetite and estimate corrosion and activation levels in the primary heat transport system
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Hassle Free Service
We develop the plan, undertake the measurements and monitoring, carry out analyses, process the data, and provide advice to protect your systems and workers. It's a complete, hassle-free, service.
Technical Abilities
iSTM Methodologies
Source Term Factors Analysis and Predictions
The main radionuclides important for source term factors analysis are Co-60 and Nb-95 (more than 80% contribution to the outage radiation fields). The source term (ST) factors are estimated from the OATM data and reflect activity changes between two consecutive outages.
The impact of various source term reduction initiatives is assessed using the source terms factors analysis, and predictions of the gamma fields at the next outage are determined. The data obtained is used to establish unit-specific trends for the outage radiation fields and the corresponding radionuclide activities.
Characterization of Primary Heat Transport Samples and Components
Spent components (filters and ion exchange resins) from the primary heat transport (PHT) purification system are characterized using in-situ gamma spectroscopy to estimate the total inventory of gamma radionuclides present. The elemental and radioisotope composition of crud and magnetite deposit samples is analyzed in our radioactive laboratory and the results are interpreted to estimate corrosion and activation levels in the PHT system.
This information is integrated with the OATM survey data to assess how the unit service and operational conditions and the system performance are impacted by the outage radiation fields. The sample analysis data can also be used for waste characterization.
Online Monitoring of Gamma Activity Transport
Continuous real-time gamma spectroscopy monitoring in several locations next to the primary heat transport coolant stream is performed for various unit states including normal operation and outages. The data is analyzed to assess the transport of the key gamma radionuclide markers which may impact the outage radiation fields.
Monitoring and Trending of Gamma Activity Transport
Regular outage activity transport monitoring (OATM( surveys are performed during unit outages. Online gamma monitoring scans are done in identified select locations during unit operation. The data is used to establish unit-specific trends in gamma fields and activities.
Characterization of PHT Oxide and Crud Samples
The samples collected during unit outages, including magnetite, oxide, and crud from the primary heat transport system, are shipped to our laboratories and analyzed for their elemental and radioisotope composition.
Our Proven Experience
Quality Assurance & Technical Standards
- ISO 9001
- Quality Management System