Dr. Daniel Blumenthal, DOE, who served on the workshop organizing committee and moderated the workshop’s session on lessons learned from international experiences, noted two challenges with organizing the session:
- Finding international experts who were involved in conversion to SI units and are still active to share their experience (most countries adopted SI units in the 1970s and 1980s).
- Scheduling conflicts for some invited speakers who were also attending the IAEA’s general conference, which was taking place on the same days as this workshop.
Despite these challenges, the committee, with the help of national and international liaisons,1 identified appropriate experts to make presentations on the topic and provide perspectives from Canada, the United Kingdom, and the European Union. These perspectives are described in the following sections.
Dr. Bliss Tracy, Health Canada (retired) and Dr. Alan Du Sautoy, director of the Radiation and Health Sciences Division, CNSC, discussed
1 For example, Dr. David Burns, International Bureau of Weights and Measures; Dr. Christopher Clement, ICRP; Dr. Edward Lazo, Organisation for Economic Co-operation and Development; Dr. Sigurður Magnússon, Icelandic Radiation Safety Authority, and Dr. David Schauer, ICRU.
Canada’s motivation to adopt SI units for radiation measurements and perspectives from their agencies’ transitions. Dr. Tracy’s talk was based largely on his own recollections of the transition during his service at Health Canada as a research scientist starting in 1978. Dr. Du Sautoy joined CNSC after the agency had already converted to SI units for radiation measurements.
There were two driving forces for Canada to adopt SI units for radiation measurements: First, Canada was moving toward the nationwide adoption of the SI for all measurements because of opportunities for commerce and trade with Europe. This move started in 1971 and was virtually2 complete by 1980. Second, the international community was adopting SI units for radiation measurements following the 1977 ICRP publication of radiation protection recommendations. Interestingly, there was not a directive to adopt SI units in radiation protection in Canada. Instead, agencies with radiation protection responsibilities judged it was the “right thing to do” and started adopting SI units gradually.
Dr. Tracy noted that Health Canada started to report radiation activity in SI units in 1978, environmental gamma exposures in 1979, and occupational exposures in 1981. His agency started using SI units for radiation measurements in publications in 1982, and by 1987 the conversion to exclusive use of SI units for radiation measurements was complete. One measure that still has not changed to SI is working level month, a measure used to express the accumulated exposure to radon decay products. Canada has considered changing this measure’s units to SI (millisieverts) but has deferred the decision for later because of the associated conversion uncertainties.
Dr. Tracy described Health Canada’s costs of conversion as “minimal,” and he said that they were not factored separately into the agency’s operating budgets. For example, there was a small one-time cost associated with converting the National Dose Registry, which maintains dose records for all Canadians who were occupationally exposed. Dr. Tracy estimated the cost to be “a few thousand dollars.” He noted that there was no sudden cost in replacing survey meters because of the approach the agency took: Staff continued to use the old meters that read in conventional units and made the conversion to SI units when they reported the measurement in writing. Survey meters reading in conventional units were used until they wore out or became obsolete, at which time they were replaced by instruments reading in SI units.
Other government departments including CNSC, Environment Canada, and Canada Customs and Revenue Agency adopted SI at the same time.
2Virtually was emphasized by the presenter because in many applications such as consumer food packaging conventional units are still shown.
CNSC’s process of conversion was gradual over 10 years. Similar to Health Canada’s approach, the costs for conversion were not estimated in a formal CBA.
CNSC and other agencies with regulatory responsibilities did not impose the conversion to SI units for radiation measurements on the nuclear power industry in Canada. Nuclear power plants in Canada can continue to use conventional units for radiation measurements onsite, but they are required to use SI units for radiation measurements for any communication with CNSC and other radiation protection organizations and when communicating with international counterparts. According to Dr. Du Sautoy, the flexibility given to the nuclear power industry allowed the conversion to SI units to proceed quickly in Canadian agencies. Conversion was not held back by the nuclear power industry’s resistance to conversion because of large costs. He thinks it is unlikely the nuclear power industry will adopt SI units for radiation measurements voluntarily, at least in the near future.
Dr. Du Sautoy noted that the continuing use of conventional units for radiation measurements in the United States hinders communication with Canada, especially in border areas. This problem is highlighted during nuclear emergency exercises that involve both countries.3
Drs. Tracy and Du Sautoy were asked how adoption of SI units affected communications with the public in Canada during the transition period. They stated that communications with the public became a priority for many governments during and after the 1986 Chernobyl accident, which was the first prominent international radiological accident. By then, Canada had almost completed the transition to SI units for radiation measurements. Similarly, Canada did not need to be concerned with the risks of retraining first responders. Organized local response for radiological incidents was also established post-Chernobyl.
The two Canadian experts were not aware of any incidents that caused inadvertent overexposure to a worker or a member of the public because of a mistake during Canada’s transition to SI units. Dr. Du Sautoy recalled one safety issue that occurred at the time of the dissolution of the former Soviet Union in 1991. That year, Canada’s Department of Foreign Affairs sent a survey team to Almaty, Kazakhstan, to measure the radioactivity at the site it considered for establishing an embassy. The team was given equipment calibrated to use conventional units but was asked to report in SI. As a result, surveyors falsely reported that radiation levels throughout the entire city of Almaty were 100 times above the country’s background levels. CNSC spotted the mistake and reported the correct levels.
3 Dr. Ansari, CDC, mentioned an upcoming training exercise in the United States, the 2017 Gotham Shield exercise. This exercise will include a hypothetical detonation near the border with Canada.
Mr. Peter Burgess, Radiation Metrology Ltd., United Kingdom, described his experience with the instrumentation industry’s transition to SI units for radiation measurements in the United Kingdom. During the transition, Mr. Burgess held positions at the National Radiological Protection Board, now part of Public Health England within the Department of Health. The National Radiological Protection Board was the leading agency for the conversion to SI units for radiation measurements in the United Kingdom.
Similar to Canada’s motivation, the United Kingdom adopted SI because of the change in the use of units for radiation measurements in the international community following international recommendations from ICRU and ICRP in the 1970s. Also, the United Kingdom recognized the benefits of using the same units as the rest of the Europe, which was also transitioning to SI units at the time.
The first regulations in the United Kingdom written in SI units were the 1985 Ionising Radiations Regulations. In 1987, the National Radiological Protection Board published an article titled “Current and Future Instrument and Dosemeter Designs to Measure the New ICRU Radiation Quantities” (Marshall et al., 1987). According to Mr. Burgess, this publication contributed to decisions by instrument manufacturers to modify their instruments to display SI units in order to expand market opportunities.
Two approaches were followed in the United Kingdom to modify instruments to SI units:
- modify instrument displays
- modify instrument energy response
For the first approach, the modification was implemented at the time the instrument was due for testing, which was every 14 months at that time. For log-scaled instruments with units specified on the dial, manufacturers fitted a new meter or changed the meter scale. For linear-scaled instruments, manufacturers changed the top plate or, more simply, pasted a new set of ranges on the instrument’s screen.
The second approach was more complicated and time consuming. It would take about 2 hours to modify the instrument. Mr. Burgess estimated that the cost was about 10 percent of that for purchasing a new instrument. He described in some detail how the modifications occurred and what the complications were.
Mr. Burgess provided several suggestions for a smooth transition to SI units for radiation measurements in the United States based on this experience in the United Kingdom. For example:
- Prepare forms, procedures, and notices related to conversion of radiation instruments to SI units in advance.
- Take parallel measurements during a 3-month period to allow people to become accustomed to the change.
- Report data acquired prior to the transition in both SI and conventional units.
- Prepare a credit card–size summary card that users can access to confirm conversions.
- Invest time and resources in training.
In contrast to the practice in Canada, the U.K. nuclear power industry also converted to SI units for radiation measurements. Mr. Burgess noted that at the time of the transition, the U.K. nuclear program was primarily a research program with little commercial focus. Therefore, there was no private nuclear power industry to resist conversion. However, radiation sources, particularly for radiation sterilization and industrial radiography, still display radiation in conventional units in the United Kingdom.
Dr. Alan Thompson, NIST, asked Mr. Burgess whether any human performance errors resulted from the conversion to SI units. Mr. Burgess responded that users were very aware of the possibility of errors during the transition, and for that reason managers had implemented several layers of checks and redundancies to avoid or catch mistakes. He added that staff in his organization were surprised with how easily everyone adopted to the change and got accustomed to working with the modified instruments.
Dr. Stefan Mundigl, a policy officer responsible for the European Commission’s activities related to the European Atomic Energy Community (EURATOM)4 Basic Safety Standards, spoke about the benefits of the European Union’s harmonization of radiation protection standards.
The EURATOM Basic Safety Standards are a set of radiation protection standards for exposure dose limits, regulatory control of practices, emergency preparedness and response, and other activities. The latest Basic Safety Standards Directive entered into force in 2014. European Union countries must ensure compliance, that is, transpose the standards into national legislation, within 4 years. Dr. Mundigl clarified that transposing
4 The EURATOM treaty is the legal binding for all activities related to radiation protection and nuclear safety among European Union member states. The treaty language has remained nearly unchanged since its inception in 1957, but some amendments have been issued to update the treaty with new scientific information. The 1980 amendment introduced the SI units for radiation measurements.
the directive into national legislation is enforced by the European Commission. The application of the standards in each country is enforced by the national regulators. The European Commission interferes only if it becomes aware that a national regulator is not enforcing the standards, in which case it can bring the member state to the Court of Justice of the European Union. Failure to use SI units for radiation measurements as required by the directive could be a reason for the European Commission to interfere.
There are other directives that complement the EURATOM Basic Safety Standards directive. For example, there are directives that set additional requirements for the protection of the health of the general public with regard to radioactive substances in water intended for human consumption as well as maximum permissible radiation levels in food and feed after a radiological accident. In addition, there is a directive related to communications during a radiological emergency. According to this directive, if a member state declares a radiological emergency, EURATOM is required to inform all European member states and the IAEA within 1 hour. The same directive establishes the ways to communicate radiological data through European Radiological Data Exchange Platform (EURDEP), a network of gamma dose-rate meters. Similar to EURATOM Basic Safety Standards, these directives are also written in SI units for radiation measurements and are required to be implemented in national legislation by member states.
The harmonization of radiation protection within the European Union proved valuable during the 2011 Fukushima Daiichi Nuclear Power Plant accident. There was a common approach among member states to sampling and monitoring imported food and feed, to setting maximum permissible levels across member states, and reporting environmental monitoring data.
Dr. Mundigl noted that the harmonization of radiation protection within the European Union supports the European Single Market concept. The European Single Market refers to the European Union as one territory without internal borders and regulatory obstacles that allow for free movement of goods, services, people, and capital within the European Union. Consumer products containing radioactivity, medical equipment containing radioactive sources, food and feed, and building materials can move freely within member states. Similarly, nuclear workers and other radiation professionals can also freely move from one country to another within the European Union.
In closing, Dr. Mundigl mentioned the Transatlantic Trade and Investment Partnership, known as T-TIP, a trade and investment agreement being negotiated between the United States and the European Union to help boost economic growth, trade, and investment. Without providing any opinions, he raised the question of how such a partnership could be implemented when there are differences in radiation safety standards, including use of units for radiation measurements, between the United States and Europe.
The workshop discussions summarized in this chapter can be organized in the following theme (Theme 4):
Experience from Canada and the United Kingdom related to converting from conventional to SI units for radiation measurements in the 1980s indicates that radiation professionals can adapt quickly to the change. The harmonization of radiation protection standards (including use of units for radiation measurements) within the European Union facilitated Europe’s response to the 2011 Fukushima Daiichi Nuclear Power Plant accident.
This page intentionally left blank.