WP5

Mitigation

SURO, Czech Republic

Tasks:

Task 5.1 Overview of regulatory approaches and international standards focused on systems and methods (preventive measures, corrective actions) to control radon in workplaces and dwellings

Leader: AGES, partners: SURO, ISS, DSA, STUK, GIG, CSTB, CVUT (M1-M60)

In many countries, various radon mitigation measures have been used in residential buildings for decades. The main objectives of this task are (i) to identify measures used for protecting new dwellings and for remediating existing dwellings, (ii) to collect information about the effectiveness of the measures, application rules and design procedures. National regulations require or in the due course of the BSS implementation will require to control radon at workplaces. In this context, the main objectives of this task are (i) to identify the regulatory approaches in the countries as well as the advantages and disadvantages of different approaches and the lessons learned with respect to specific and general workplaces (ii) to identify the radon control techniques applied in the countries for existing (corrective actions) and new workplaces (preventive measures), and to give an overview of their effectiveness, sustainability, cost as well as lessons learned. Current experience on corrective actions to reduce indoor radon concentration in existing buildings and preventive measures for buildings under construction largely refers to small buildings, such as houses. Limited information is available for large buildings, mainly schools. In this task, a review of experience on radon mitigation (corrective actions and preventive measures) in different countries will be carried out, including the analysis of some case studies, in order to evaluate the differences between methods usually adopted in houses and those adopted in large buildings and to identify effective strategies to reduce/prevent indoor radon concentration in large buildings (e.g. public or industrial buildings).

This task is subdivided into 3 subtasks:

  • Subtask 5.1.1 – Overview of radon risk mitigation measures used in dwellings
  • Subtask 5.1.2 – Overview of regulatory approaches radon control systems and methods used at workplaces
  • Subtask 5.1.3 Strategy for large scale buildings mitigation and prevention: overview of regulatory
    approaches and differences with strategy used for small buildings

Task 5.2 Innovative radon control technologies and strategies for mitigation systems in buildings

Leader: SURO, partners: CVUT, AGES, STUK, ISS, CSTB (M1-M60)

Apparent conflicts between indoor air quality requirements and energy performance of buildings have been identified based on indoor radon measurement in new houses and also in existing buildings. Harmonization of energy saving technologies and radon control technologies and other public health care programs and tools focused on indoor air quality in general is actual challenge in radiation protection that requires an application of innovative mitigation systems and methods. Explanation of deterioration of indoor air quality after refurbishment of existing buildings, increasing of indoor radon levels and other indoor contaminants cannot be simplified only by reducing the air exchange rate. Radon entry rate dynamics have to be considered and involved accordingly in overall evaluation. Development of strategies and measurement protocols of air- exchange rate determination using tracer gas measurement techniques is essential part of radon control and reducing systems optimized operation.

The evaluation of remediation strategies in buildings constructed with materials emitting high levels of radon, including residues of NORM industries will be carried out supported with calculation of radon entry rate into model room utilizing modelling tools. Utilization of continuous radon monitors (CRM) for exposure assessment and radon diagnostic procedures focused on radon entry pathways identification and quantification is common practice for radiation protection professionals and mitigators. Detection and operational properties of continuous monitors are designed to meet the technical requirements accordingly.

In a further activity of this task, a complex experimental work will be performed in radon/ thoron calibration facilities focusing on evaluation of technical specifications and fundamental detection properties of active radon monitors (time response to changes of radon concentration; detector response in mixed radon-thoron atmosphere; active vs. passive air sampling; efficiency of radon progeny filtration; environmental influencing factors – aerosol conditions; air humidity; air temperature etc.) which is essential in case of facilities and buildings equipped with forced ventilation systems where high radon fluctuations and dynamics can be observed with high measurement uncertainty.

In many countries, waterproofing materials placed over the structures in contact with the soil are considered as a basic measure for protecting new buildings against radon. The barrier properties of waterproofing materials against radon penetration are usually expressed in terms of the radon diffusion coefficient. The primary objectives of this special activity are (i) to objectify the process of determining the radon diffusion coefficient in waterproofing materials, (ii) to evaluate the effect of imperfections (air bubbles, microcracks and microscopic holes) in the waterproofing materials on the value of the radon diffusion coefficient, (iii) to investigate the temperature dependency of the radon diffusion coefficient in the range that corresponds to the real exposure conditions (non-heated buildings x buildings with underfloor heating), and (iv) to determine the radon diffusion coefficient of frequently used building materials that create substantial part of the structure, or through which radon penetrates from the source to the interior.

The task is split in 4 subtasks:

  • Subtask 5.2.1 – Harmonization of energy saving technologies and radon control technologies with respect to radiation protection and general indoor air quality requirements
  • Subtask 5.2.2 – Radon control technologies focused on mitigation of radon exhalation from building materials
  • Subtask 5.2.3 – Utilization of continuous radon monitors for control of active operation elements of radon mitigation systems
  • Subtask 5.2.4 – Advanced methods of radon diffusion coefficient determination in radon-proof membranes used as a passive radon preventive and remediation measures

Task 5.3 Evaluation of radon mitigation systems with respect to their variability, sustainability

Leader: DSA, other partners: CVUT, AGES, SURO, STUK, CSTB, ISS (M1-M60)

Although it is well established that radon levels can be reduced significantly by moderate costs, it remains a problem that, in some cases, the target levels of radon are not reached, or the mitigation could even fail to reduce radon at all. A high success rate and long-term efficiency of such actions will be important for the actual risk reduction, optimization and cost-efficiency, and probably also for the willingness among homeowners to initiate radon mitigation. The aim of this activity is to increase knowledge on the variability and long-term efficiency of radon mitigation in homes and to identify potential for improvement. Existing and new data sets from mitigation campaigns and radon prevention projects in Czech Republic, Finland, Italy, France, Norway and Austria will be analysed. Factors contributing to the variability and sustainability will be identified, and recommendations for further improvement of mitigation systems, including both technical issues as well as competence, quality assurance and information to the public will be provided. In large buildings, typically schools, other public buildings and many workplaces, both the technical aspects, ownership and responsibility issues differ compared to smaller houses and dwellings. The aim of this second activity is to collect available data and information on the variability and sustainability of radon mitigation systems, including active/passive systems performance and organisational measures, and to identify the main factors contributing to the successful implementation of these measures.

This task has 2 subtasks:

  • Subtask 5.3.1. Variability and sustainability of radon mitigation systems in homes
  • Subtask 5.3.2. Variability and sustainability of radon mitigation systems in big buildings (schools, kindergartens and other workplaces or public buildings)

Task 5.4 Radon reducing and control technologies applied in underground workplaces (mining industry; public access caves and mines; civil protection facilities etc.)

Leader: SURO, other partners: GIG, CVUT, AGES, STUK, CSTB (M1-M60)

In this task, an overview of strategies and radon mitigation systems used in underground workplaces will be performed with special attention paid to site specific aerosol conditions, operational and occupational limitations and mitigation systems and techniques restrictions and limitations. Application of ventilation system modelling will be used for prediction of radon and radon progeny occurrence in the atmosphere of underground workplaces. Ventilation system efficiency vs. radon progeny ingrowth will be analysed and the use of non-radioactive aerosols size distribution for radioactive aerosols size distribution evaluation will be utilized. In-situ measurement campaigns will be carried out in various underground workplaces and facilities covering specific measuring conditions such as aerosol concentration and size distribution, forced ventilation and other HVAC systems operation, air temperature and absolute air humidity affecting accuracy of occupational exposure and personal effective dose assessment and mitigation efficiency evaluation. Unique experimental devices enabling quantification of radon progeny attached and unattached fraction, radioactive aerosols size distribution will be utilized. The determination of the annual personal effective dose of workers caused by radon and its decay products could be carried out based on personal monitoring or a working environment monitoring using continuous monitors or integral monitoring systems of the radon activity concentration or the equivalent radon activity concentration. Mitigation procedures leading to reduction of occupants’ exposure through a modification of methods of work and other organizational measures in workplaces such as limitation of time of individual workers spent at certain location (underground facilities) are dependent on accuracy of workers exposure assessment and personal dose determination. Comparison of personal dose assessment of workers from radon and radon progeny based on personal dosimeters application and workplace continuous and integral monitoring methods will be carried out and evaluated in various underground workplaces to increase the efficiency of mitigation systems that are primarily based on organizational measures.

Task 5.4 has 3 subtasks:

  • Subtask 5.4.1 – Overview of strategies and measures of radon risk reducing and control used in underground workplaces
  • Subtask 5.4.2 – Development of measurement protocol of radon progeny attached and unattached fraction, radioactive aerosols size distribution for the purpose of radon mitigation systems efficiency evaluation
  • Subtask 5.4.3 – Comparison of personal dose assessment of workers from radon and radon progeny based on personal dosimeters application and workplace continuous and integral monitoring

Task 5.5 Radiation risk mitigation measures applied in NORM involving industries and remediation of legacy sites

Leader: GIG, other partners: SURO, AGES, DSA, BfS, IRSN, STUK (M1-M60)

An overview of strategies and technologies already applied in ongoing (i) NORM involving industries and feasibility studies of NORM treatment based on mixing, dilution, recycling and underground/landfill/radioactive waste repository disposal considering occupational exposure, exposure of the members of the public and the environment based on outcomes of WP 2 will be provided, (ii) non uranium underground mining, (iii) oil and gas, (iv) thermal energy, (v) water treatment plants. A further overview of remediation options already applied and feasibility studies on existing legacy sites will be prepared. Case studies on (i) post-industrial/non uranium mining sites, (ii) radium production, (3) uranium mining industry (waste rock dumps, shafts, tailings) with the attention paid to exposures to members of the public and to the environment if applicable. A third overview of strategies and water treatment technologies reducing the level of natural radionuclides (and non-radioactive co-contaminants) in drinking, formation and process waters. Development of new mitigation/preventive methods, optimisation existing ones considering either industry specific circumstances or necessary emerging residues treatment and feasibility study on cross-industry application of technologies already applied in coal mining.
The task will provide recommendations for operators and regulators regarding the use of models in decision- making processes in remediation of NORM legacies. The topic is relevant to implement the requirements from the BSS in relation to NORM as it would help in addressing specific BSS requirements for long-lasting exposure situations / remediation strategies.

The task is split in 4 subtasks:

  • Subtask 5.5.1 – Strategies and technologies used for NORM treatment and remediation of legacy sites
  • Subtask 5.5.2 – Prevention and mitigation of radiation risk caused by formation water
  • Subtask 5.5.3 – Evaluation of NORM treatment and remediation options using radioecological models
  • Subtask 5.5.4 – Overview of international standards and regulatory approaches focused on radiation risk
    mitigation measures applied in NORM involving industries and facilities
X