Purpose

The purpose of this procedure is to ensure the correct use of UVC sources and to ensure that radiation protection practices at NTNU comply with regulatory requirements and safeguard the safety of employees, students, and others at NTNU.

Scope and anchoring

This procedure applies to all units, employees, and students affiliated with units that use UVC sources belonging to NTNU. The procedure is a risk-reducing measure for work involving UVC sources.

This procedure is governed by the Guidelines for radiation protection and the use of radiation sources.

Definitions

Ultraviolet radiation (UV)
Electromagnetic (optical) radiation within the wavelength range of 100–400 nm. UV radiation is divided into three types: A, B, and C:

• UVA: Electromagnetic radiation with wavelengths between 315–400 nm
• UVB: Electromagnetic radiation with wavelengths between 280–315 nm
• UVC: Electromagnetic radiation with wavelengths between 100–280 nm

Typical UVC sources
Mercury-based UVC sources emit a narrow and intense radiation peak centered around 254 nm, whereas high-pressure UVC sources are broader in spectrum. Sunlight contains wavelengths down to approximately 180 nm.

UVC characteristics
Air effectively blocks radiation below 180 nm. Typical applications of UVC sources include sterilization of air, surfaces, and water, as the radiation kills bacteria, viruses, and other microorganisms. UVC radiation can damage eyes and skin, though there are significant individual differences in human sensitivity—particularly with regard to skin.

UVC categories
UVC sources are categorized into four risk levels (0, 1, 2, 3) based on how quickly they can deliver doses that exceed exposure limits. High-risk sources (category 3) may exceed exposure thresholds in under 17 minutes. See the table in the Guide for the safe use of shortwave ultraviolet radiation (UVC).

The exposure limits are defined by ICNIRP based on individuals who are most sensitive to UVC radiation (typically fair-skinned individuals who burn easily in the sun).

ICNIRP (International Commission on Non-Ionizing Radiation Protection)
An international body that develops guidelines for the safe use of various radiation sources, including UVC sources.

Responsibilities

Line manager

The line manager holds overall responsibility for ensuring proper radiation protection within the unit. The line manager shall fulfill the duties described in the Guidelines for radiation protection and the use of radiation sources.

The line manager shall ensure that academic supervisors and, where applicable, Instrument custodians are appointed for the unit’s UVC sources—or shall assume these roles personally if necessary.

Procedure for working with UVC sources

Local radiation protection coordinator

The local radiation protection coordinator shall fulfill the responsibilities described in the Guidelines for radiation protection and the use of radiation sources.

Academic supervisor

The academic supervisor shall, at a minimum, carry out the tasks defined in the Guidelines for radiation protection and the use of radiation sources.

In addition, when working with UVC sources, the academic supervisor shall:

• Assess whether it is appropriate to appoint a dedicated Instrument custodian. If a new UVC source is to be acquired and no such person is appointed, the academic supervisor assumes responsibility for the tasks listed under the section Instrument custodian.
• Ensure that incorrect use of UVC sources is prevented.
• Routinely verify that required personal protective equipment is readily available and in good condition.
• Develop local procedures for UVC sources owned by the unit.
• Ensure categorization of the unit’s UVC sources.
• Ensure that required maintenance and inspections of the equipment are carried out in accordance with the manufacturer’s instructions.
• Assess the need for vision examinations in accordance with the Guidelines on optical radiation sources and vision examinations.

Use the UVC source checklist (HMSRV3701B) as a supporting tool during risk assessments.

Instrument custodian

The Instrument custodian for UVC sources shall, at a minimum, carry out the tasks described in the Guidelines for radiation protection and the use of radiation sources.

Users of radiation sources

Each individual user of radiation sources shall carry out the tasks described in the Guidelines for radiation protection and the use of radiation sources.

Documentation

Information Binder / Local Procedures

The information binder and/or local procedures shall be available at the locations where UVC sources are used. These may, for example, be included in a laboratory HSE (Health, Safety, and Environment) information binder, posted locally, and/or distributed to others (such as janitorial and cleaning personnel) as needed. Consider whether both Norwegian and English versions of the documents are necessary.

Information Binder / Local Procedures for UVC Sources shall at minimum include:

General Information

• Name of the academic supervisor, if applicable the instrument custodian, and the local Radiation Protection Coordinator
• Instrument-specific documentation
  • Manufacturer, model, age, owner, and serial number
  • Regulatory labeling
• Risk assessment

Instructions for users

Instructions for practical use, how to shut down the system, safety precautions, any required logging, use of radiation monitors if applicable, maintenance, routine checks of technical safety equipment, and more. Procedures for activating safety systems and verifying their proper function

Emergency Procedures

Description of relevant emergency situations, how they should be managed, and who should be notified in case of accidents or unintended exposures. Reporting deviations in the deviation reporting system

• Complete operating and maintenance manual
• Emergency Procedures (repeated section in original)
• Procedures for the use of personal protective equipment. Instructions on how and when protective equipment should be used and possible malfunctions

Safety and Technical Requirements

Labeling and Signage

All entrances to rooms containing UVC sources and all equipment must be clearly labeled with warnings about the potential exposure to harmful UVC radiation. See Chapter 4 "Technical Requirements" in the Guide for safe use of shortwave ultraviolet radiation (UVC) (pdf). Also refer to physical protection of radiation sources.

Protective Equipment

Appropriate personal protective equipment (PPE) must be available for all personnel who need to be present in areas where exposure to UVC radiation above limit values may occur. This may include eye and face protection (goggles/visor), long protective gloves, and long-sleeved work clothing.

Dosimetry

Exposure to UVC radiation shall be limited as much as practically possible. The primary safety objective for working with UVC sources is the containment and shielding of all radiation. In cases where this is not possible, radiation levels must be measured to assess potential risk.

UVC sources are categorized into four classes (0, 1, 2, 3) based on how quickly they can deliver doses exceeding the limit values, where high-risk sources (category 3) may exceed exposure limits in less than 17 minutes. See the table on page 8 in the Guide for safe use of shortwave ultraviolet radiation (UVC).

Measurement for categorizing UVC sources must be carried out according to the method described in Norwegian Standard NS-EN 14255-1. The person conducting measurements must be particularly careful to use appropriate personal protective equipment. The central radiation protection coordinator has access to measurement equipment.