Purpose

The purpose of this procedure is to ensure the correct use of electron microscopes, as well as to ensure that radiation protection work at NTNU complies with regulatory requirements and safeguards the safety of employees, students, and others at NTNU.

Scope and Foundation

This procedure applies to all units, employees, and students at units that use electron microscopes owned by NTNU. The procedure is a measure to reduce the risk associated with working with electron microscopes.

The Guideline for radiation protection and use of radiation sources forms the governing basis for this procedure.

Definition

In an electron microscope, an electron beam is emitted from a filament. X-rays are generated when the electron beam strikes an object. Electron microscopes are primarily used for imaging objects and analyzing elemental composition. The beam is encapsulated.

Responsibility

Line manager

The line manager has the overall responsibility for ensuring proper radiation protection within the unit. The line manager shall carry out tasks as described in the Guideline for radiation protection and use of radiation sources.

The line manager shall ensure that there are designated persons with academic responsibility and, if applicable, instrument responsibility for the unit’s electron microscopes, or hold this role themselves if necessary.

Procedure for Working with Electron Microscopes

Local radiation protection coordinator

The local radiation protection coordinator shall at a minimum perform tasks described in the Guideline for radiation protection and use of radiation sources.

Electron microscopes are subject to mandatory notification according to section 13 of the Radiation protection regulations.

Academic supervisor

The academic supervisor for electron microscopes shall at a minimum perform tasks described in the Guideline for radiation protection and use of radiation sources.

In addition, the academic supervisor shall ensure the following when using electron microscopes:

• Assess whether there is a need for a dedicated instrument custodian for the electron microscope, and if necessary appoint an instrument custodian (with a deputy if required). The academic supervisor shall evaluate whether the relevant persons have the competence to serve as instrument custodian. If no instrument custodian is appointed, the academic supervisor shall  carry out the duties listed under instrument custodian.
• Inform the local radiation protection coordinator of all new acquisitions, relocations, and disposals of electron microscopes.
• Conduct risk assessments as described in the Guideline for radiation protection and use of radiation sources.
• Ensure that all electron microscopes, or the room where the instrument is located, have adequate labeling and signage.
• Inform external persons present at the workplace (cleaning personnel, craftsmen, and others) about the electron microscope’s key properties and hazards, cleaning routines, the significance of warning signs, contact information, and more.
• Conduct regular control measurements.
• Assess whether users have sufficient competence to function as authorized users of the unit’s electron microscopes.
• Secure electron microscopes against sabotage, fire, and water damage.

Instrument custodian

The instrumentcustodian for electron microscopes shall at a minimum perform tasks described in the Guideline for radiation protection and use of radiation sources.

Authorized user

Authorized users must have sufficient competence to independently assess and operate the electron microscope safely. Sufficient competence means instrument-specific knowledge of startup procedures, instrument settings, safety devices, shutdown procedures, any emergency procedures, the content of the information manual, any radiation measurements, and more.

Other Users

May use the electron microscope upon agreement with authorized users or the instrument custodian.

Documentation

Information manual

Each electron microscope shall have an information manual containing at minimum the following information:

General information

• Name of the academic supervisor, instrument custodian, and the local radiation protection coordinator
• List of users (authorized and others)
• Instrument-specific documentation

• • Manufacturer, model, age, owner, serial number
  • Current strengths [mA], maximum peak voltage [kV]
  • Regulatory labeling

• Risk assessment
• References to (or copies of) data sheets, radiation protection regulations, and similar documents
• Reference to local and central emergency response plans

User instructions

Operating instructions for practical use, safety precautions, logging procedures, locking mechanisms, any use of radiation monitors, and more.

Emergency Procedures

• Procedures should describe how to correctly shut down the apparatus, confirm that no radiation is present when the equipment is turned off, measures to be taken in the event of radiation injury, contact information, and reporting.
• Use images/figures in the emergency procedures where appropriate.
• Consult emergency procedures as needed: locally and/or distributed to others (for example, janitorial and cleaning personnel).
• Refer to the central and local emergency response plans, DFU10 Accident and Incident Involving Radiation Sources.
• Procedure for preparedness and response in the event of an accident or incident involving a radiation source.
• Consider whether emergency procedures should also be available in both Norwegian and English.

Logbook

Each electron microscope shall have a logbook or electronic log containing:

• Service work and significant changes to instrument configuration.
• Performed control measurements.

Safety and Technical Requirements

Labeling and Signage

Electron microscopes shall be labeled in accordance with Chapter 5 of the Workplace regulations. Use standard signage for "Danger– High voltage".

Some electron microscopes are equipped with ion pumps that generate magnetic fields, which may adversely affect pacemakers. Such electron microscopes must be labeled to indicate the required safety distance for individuals with pacemakers. The correct safety distance must be specified in the instrument’s user manual.

Labeling shall be in Norwegian; equivalent information may be provided in other languages if needed.

Physical security

All radiation sources shall be secured against theft, sabotage, fire, and water damage. Rooms or areas containing electron microscopes should have restricted access. Technical measures to prevent theft and sabotage (e.g., securing the equipment to fixed installations) and to protect against fire, water, or other types of damage must be implemented. See also Physical Security of Radiation Sources in the Guideline for radiation protection and use of radiation sources.

Control measurements

According to section 24, paragraph a) of the Radiation protection regulations, electron microscopes must be shielded such that the dose rate on the surface does not exceed 5 μSv/h.

Measure the radiation dose in the surrounding area (excluding the direct beam) routinely at least once per year, after service, and following any significant changes to the instrument setup. Record the results in the instrument’s logbook. Use a radiation monitor appropriate for the type of radiation. Contact the local or central radiation protection coordinator if assistance is needed to perform these measurements.