Radiation Protection for Nuclear Plant Design

The three key radiation protection principles

Radiation protection has key three principles which ensure workers, and the public are protected from the harmful effects of ionizing radiation. All these are part of the ALARA approach – As Low As Reasonably Achievable – which aims to avoid individuals receiving even the smallest dose. What’s more, taking economic aspects into account, the ALARP principle – As Low As Reasonably Practicable – can be applied. The ALARP approach is achieved through forward-thinking design solutions and taking these key radiation protection principles into account.

The key principles to radiation protection are:

• Time
  The effects of radiation exposure build up over time. It is therefore important that work near radioactive sources is completed as quickly as possible and that workers time in critical areas is limited. Monitoring radiation levels in critical areas within the nuclear power plant is crucial in deciding on the most efficient and effective approach to work and maintenance on equipment, while minimizing workers’ exposure.

   

• Distance
  Being further away from radiation sources reduces radiation exposures. In fact, radiation exposure is inversely proportional to the square of the distance, meaning that being twice as far away from the radiation sources reduces exposure by a quarter (and not a half). In nuclear power facilities, remote handling and robotics are being used more often to increase the distance between workers and equipment.
  
  
• Shielding
  Radiation shielding usually comprises of one or more barriers of lead, concrete or water which will absorb some radiation as it passes through. The amount and type of shielding primarily depends on the type of radiation and therefore its source. However, it is important to note that the shielding’s installation must comply with all regulations and standards as laid out in the operator’s licence.
  
  

Ensuring safety and security throughout the lifecycle of a radiation protection laboratory

Whether you are building a new laboratory or converting an existing facility, you will no doubt need to commission and schedule ongoing tests on a variety of systems for generating ionizing radiation as part of the process. Such tests require in-depth knowledge of several types, processes and working methods. As experts in their field, our TÜV SÜD can leverage their experience to offer support with:

1. Examining approval requirements when submitting an application,
2. assessing structural, technical and administrative radiation protection measures and organization,
3. reviewing radiation protection documentation such as radiation protection instructions or work instructions,
4. monitoring radiation and activity, from conception to implementation and maintenance support,
5. giving advice and guidance on external and internal radiation exposure controls and shielding design,
6. optimising using recognized computer codes,
7. measuring clearance.

When the time comes to decommission your control area, from small single room laboratories and radiation therapy facilities to entire hospitals or plants generating ionizing radiation, you usually need approval from the relevant supervisory authorities covering residues, buildings, rooms and components. The experts from TÜV SÜD can help you when you decide to stop handling radioactive substances – from liaising with your respective authority to carrying out the control measurements required.

Protecting your radiation protection laboratory

In the close-up, enclosed setting of a radionuclide laboratory, the three principles of radiation protection are more important than ever. A clear set of rules must be in place to ensure the safety of everyone at the facility. These may include measures such as monitoring radiation levels with dosimeters, wearing protective clothing, and installing radiation shields on equipment.

TÜV SÜD’s experts can not only support you in drafting an Operations Manual for your radionuclide laboratory to guarantee the highest level of safety, but also design procedures to ensure, for example, any contaminated clothing or material is disposed of in accordance with approved guidelines.

Monitoring in our own radiation safety lab

TÜV SÜD’s own filter test laboratories provide multiple test methods to determine the retention efficiency of iodine filters and filter efficiency and performance index of the materials used. This is invaluable to nuclear power plant operators, iodine therapy stations as well as manufacturers of active carbon or respiratory filters. What is more, we can perform on-site testing of aerosol filters with uranine testing equipment according to DIN EN ISO 16170 as well as on-site inspections of Iodine filter systems.

To ensure the highest quality of our services and testing, we have achieved the following accreditations:

• DIN ISO 9001:2015 for TÜV SÜD Energietechnik GmbH BW.
• DIN EN ISO/IEC 17025:2018 for TÜV SÜD ET’s radiation measurement laboratory.
• DIN EN ISO/IEC 17020:2012 (Type A) for TÜV SÜD ET’s Radiation Protection Department as part of the energy technology inspection body for in the inspection field of radiation protection.

We understand how even small levels of radiation can affect the smooth operation of equipment and technology within a facility or laboratory. Using cutting edge equipment, our experts can detect and measure decay and make sure equipment is always operating within safe, tolerable parameters. We can then advise on controlling external and internal radiation exposure as well as improved shielding designs.

What kind of radiation measurements are carried out in TÜV SÜD’s laboratories

In our radiation measurement laboratories, we carry out radioactivity determinations in materials of all kinds, primarily using gamma spectrometry, alpha and beta total measurements and liquid scintillation measurements (for soft beta emitters such as H-3, C-14, Ni-63 and others). Our measuring equipment is ideal for measuring both radon and natural radioactivity, particularly from the thorium and uranium decay series.

Dealing with naturally occurring radioactive material across industry

With the incorporation of EURATOM basic standards into national law within EU member states, further measures to protect the individuals and groups are now needed. For example, employees who handle NORM (Naturally Occurring Radioactive Material) residues at work are considered part of the general population.

What’s more, in certain sectors, such as the titanium dioxide, steel, and oil and gas industries, materials can be handled that contain small, but not insignificant, amounts of naturally occurring radiation. And in the waterworks sector, filter gravel, sand, exchange resins and other materials used in groundwater treatments and subject to chemical processes are classed as residues that require assessment.

In such cases, employers are responsible for minimising the exposure of their employees and others to hazardous materials, complying with NORM exposure limits as set down by law, and for the safe disposal of any waste resulting from NORM.

Processing NORM usually falls into one of three categories.

1. Using radioactive substances for their chemical or physical properties.
2. Producing radioactive waste because of extracting substances from natural minerals or ores.
3. Moving radioactive material from one part of the environment to another where it is not normally found.

TÜV SÜD has supported clients from a wide cross-section of industries to develop and implement a NORM safety policy. This would set out general precautions for minimising exposure within the organisation as well as defining any personal protective equipment needed when handling material. The policy also covers management plans for storing, labelling, cleaning, and disposal of NORM waste.

Radon measurement for homes, offices, and public buildings

According to the World Nuclear Association, Radon accounts for around 42% of background radiation. Radon is a naturally occurring radioactive gas that is emitted from the ground by certain rocks and soils. As it disperses easily into the atmosphere, Radon levels are generally low outdoors. However, the radon hazard builds up in indoor environments such as offices, schools, and homes and, with long-term exposure, can be a major cause of lung cancer.

What you can do

Mitigations from radon are relatively straightforward. High radon levels in buildings are usually caused by air flowing into the house through gaps and cracks in the groundwork, flooring, or piping. The flow of air is caused by a difference in pressure outside (high) to inside (low). Radon hazards can be minimised by

• Installing an underfloor radon sump system
  One of the most effective methods; a sump (a small chamber or void) is dug next to the building. radon is drawn into the sump by a fan through a pipe and then vented out into the atmosphere.
• Depressurising the soil
  This involves ventilating the underfloor and drawing out air and gas (sometimes using a fan) through a pipe leading to the roofline. In addition, air bricks could be installed to help further ventilate the building.
• Introducing positive ventilation
  Air is blown into inhabited spaces through the roof or loft, thereby cutting radon hazards by diluting the gas in the building and reducing seepage into the structure through increased pressurisation.
• Identifying and sealing entry points and foundation cracks
  this is one of the most disruptive solutions, as carpets, floorboards and other fittings will need to be removed. It is important that all cracks and points are sealed otherwise it may have a negligible effect on radon levels.

TÜV SÜD’s radiation laboratory can help you measure the level of radon in buildings and workplaces and supports you to fulfil your obligations as the responsible person under the German Radiation Protection Act (Sections 124 and 128 Strahlenschutzgesetz – StrlSchG). In addition, our experts have been determining average radon air concentrations for competent authorities several years and can identify areas in which the legal reference values for radon-222 in buildings and workplaces are exceeded. We can also help manufacturers of building products to determine the specific activity of radionuclides (as per Section 134 StrlSchG) before placing products on the market.