Extensive training, monitoring help shield Bruce Power workers from dangerous radioactive particles
In late 2009, Bruce Power was in the process of refurbishing two dormant nuclear reactors at its power plant in Tiverton, Ont., three hours north of Toronto. The Unit 2 refurbishment went off without a hitch, but when it came time to complete Unit 1, contractors were unknowingly exposed to radiation. When the workers were cutting and grinding feeder pipes, a radioactive particulate from their work was being released into the air.
While the workers were being monitored for beta radiation, they were not being monitored for the more dangerous alpha radiation because “all calculations would have told you there wouldn’t be an expectation of alpha in the area,” says Duncan Hawthorne, president and CEO of Bruce Power.
While the ratio of beta to alpha is typically 10,000 to one, in this case, the ratio was seven to one.
A total of 557 workers were potentially exposed to the alpha radiation. Bruce Power underwent an exhaustive campaign of testing these workers. It found less than 10 workers received radiation doses greater than five millisieverts (mSv) and all had doses less than 10 mSv. The regulatory limit set by the Canadian Nuclear Safety Commission (CNSC) is 50 mSv per year for a nuclear energy worker.
At the time of the incident, Bruce Power offered a helpline for confidential assistance to workers and their families trough the Radiation Safety Institute of Canada, and it subsequently implemented a comprehensive routine program to monitor workers for alpha radiation using specialized instrumentation.
“We changed the rules to assume alpha would be there rather than assume it wouldn’t be there,” says Hawthorne. “We wanted to get back to the principle of as low as reasonably achievable.”
This incident is a reminder that nuclear power plant operators need to be constantly aware of the potential for radiation exposure and put all appropriate measures in place to protect their workers.
Radiation is of particular concern because it has been linked to certain types of cancer. Also, at extremely high doses, radiation exposure can cause biological effects, skin reddening, nausea, vomiting, cataracts and even death.
The government of Canada’s Radiation Protection Regulations stipulate all nuclear power plant operators must implement a radiation protection program. One of the first steps is to undergo a risk assessment process for all job types to determine which ones are most at risk for radiation exposure.
About 70 per cent of employees at Bruce Power are classified Nuclear Energy Workers (NEWs) who regularly face a greater risk of radiation exposure. Also, operations and maintenance personnel often work with equipment that either contains radioactive material or has been contaminated with radioactive materials, says Steve Mahoney, president of the Radiation Safety Institute of Canada in Toronto. But a large number of the 4,200 workers at Bruce Power do not face radiation risks, including human resources, engineering and clerical staff.
Once the risks are identified, the radiation protection program should outline the hazards, protection — from PPE to training — controls and work permits.
For example, one common hazard in nuclear reactors is tritium. It’s a radioactive isotope of hydrogen that can be absorbed into the skin or inhaled. Workers at Bruce Power are given an instrument to measure for tritium as well as an air supply suit to protect themselves. They also need a permit to work with the substance, says Frank Saunders, vice-president of nuclear oversight and regulatory affairs at Bruce Power.
When it comes to radiation exposure, Bruce Power follows the basic principle of as low as reasonably achievable (ALARA), says Hawthorne, and the tenets of achieving that are time, distance and shielding.
“We need to plan, train, rehearse in such a way to minimize the time employees spend in an area where there may be a radiation field,” he says.
For example, when workers need to access high-risk areas for maintenance or to conduct a specific job, they are given a special radiation meter with an alarm. It is preset, so once the radiation levels reach a certain number, an alarm goes off.
“Once that alarm goes off, you have to leave the area, whether you’re finished the job or not,” says Hawthorne.
If at all possible, the company tries to create an increased distance away from radiological hazards. During the dismantling of the reactors, a lot of work was done using robotic equipment so there was no worker exposure.
Shielding is a common control mechanism, which is often achieved through lead blankets. For example, if a worker has to do some welding and opens a pipe valve, a lead blanket will be wrapped around the pipe, which reduces the radiation field by about one thousand, says Saunders.
Bruce Power has 100 radiation prot
ection technicians who are responsible for ensuring all aspects of the radiation protection program run smoothly. It also has about 30 health physicists who are very specialized workers — the most senior ones are signed off by the CNSC — and they are responsible for reviewing and approving a high-risk job before workers can do it.
Nuclear power plants are required to monitor workers and send dosage information to the federal government’s National Dose Registry several times per year.
To monitor exposure, all NEWs and workers in the plant at Bruce Power are required to have a dosimeter on them at all times, which gets sent to the lab every two weeks to see if they have been overexposed. NEWs also undergo monthly urine samples to make sure nothing has been inhaled or ingested, and they are required to undergo an annual whole body scan that looks for any pickup of radioactive materials in the body.
There are specialty dosimeters for workers where certain body parts may face a higher exposure. For example, a mechanic working on something that has a radiation field might get a different dose on his hands than his body, so he will receive a specialty dosimeter to wear on his finger, says Saunders.
The CNSC prescribes equivalent dose limits for certain organs and tissue sets per year: lens of an eye (150 mSv); skin (500 mSv); and hands and feet (500 mSv).
There are also different levels for pregnant workers as the fetus is very vulnerable. When a worker becomes pregnant, she is required under the CNSC to notify her employer in writing, then her dose amount is limited to four mSv for the balance of the pregnancy.
Bruce Power does not allow pregnant women in the power plant at all, and it regularly accommodates them into other roles.
“For example, if an operator was pregnant, she’d work in procedure writing areas or training, typically where they know their knowledge is valued, but they don’t need to be in the plant to do that,” says Hawthorne.
In any case, if a worker is exposed to too much radiation, he needs to be removed from that workplace immediately, says Mahoney. The CNSC would need to be notified and a thorough investigation would take place. He cannot return to the workplace until cleared by his doctor and the CNSC, says Mahoney.
Bruce Power stopped work when alpha was discovered during the Unit 1 refurbishment in 2009, and workers did not return to the project until the area was free of contamination.
The CNSC has published an extensive regulatory guide for radiation safety training programs that all nuclear power plants are required to follow. It outlines a six-step process for developing a program, including identification of specific training needs and program design.
Training for Bruce Power employees is provided internally and comes in various forms, depending on the level of risk present in each worker’s role. All employees wear a coloured badge to indicate their certification level, which corresponds with the level of training they have received.
The first level is red which indicates the worker does not have any radiation working rights at all.
The next level is orange which means a worker can walk around the plant without having an escort but he can’t do any radiation work. This is the very fundamental level and requires two days of basic “Radiation 101” training, which covers the use of contamination meters and facility access.
A yellow badge gives a worker individual working rights, and he may or may not require radiation protection supervision, depending on the nature of the risk. This qualification involves three weeks’ training, which covers routine radiological survey and decontamination.
The top level is green and this is for people who can supervise those with a yellow badge. This requires five weeks’ training and covers segregation and handling of radioactive waste, hazard surveys, posting, and response and recording. All badges require an annual recertification.
One step in CNSC’s training guide is continuous learning, and this is a very important aspect of radiation safety training, says David Shier, president of the Canadian Nuclear Workers Council in Toronto.
“It just reinforces protection issues,” he says. “There may be new equipment, new limits set at different times over the years, and people need to be kept updated on what’s happening and sometimes there’s lessons learned from some incidents,” he says.
New employees at Bruce Power receive a detailed orientation around radiation, says Hawthorne.
Visitors to the site are also required to undergo radiation awareness training.
“The idea being before anyone gets access to the power house, they know exactly what’s in there, how it’s designed and know how to use all the monitoring (devices) and obey signage,” he says.
All contractors coming in to work on a project need appropriate radiation safety training as well.
“I wouldn’t treat a contractor any different than staff,” says Mahoney. “Anyone working on the site should be aware and it could even be more important to make sure contractors are trained because you don’t necessarily control them directly as an employee.”
When it comes to PPE, workers in nuclear power plants need conventional items — such as coveralls, safety glasses, ear protection, hard hats and safety footwear — but if they are in a high radiological area, they need plastic suits and respirators.
All containers and devices that contain radioactive nuclear substances are labelled in accordance with WHMIS legislation. And high radiation risk areas are identified with signage containing the radiation-warning symbol.
If workers have concerns about radiation, they can make sure it is brought up at the joint radiation protection committee, says Shier. The requirement to have the committee is drafted in the collective agreements between nuclear operators and the Power Workers Union, and it meets quarterly.
“It allows for shop-floor input to any radiation protection issues,” he says. “Workers actually have the right to refuse, there’s a lot of processes in place, they are encouraged to bring issues to their supervisor… it’s kind of ingrained into the culture.”
The collective agreements also include the negotiated right to shut down unsafe work at these facilities.
Emergency preparedness is of the utmost importance at Bruce Power.
“If we had a nuclear event such that we had a line break or a fuel channel drop, then we need to have the ability to deal with that. A lot of the operational response happens by design,” says Hawthorne. “We have an automatic shutdown system that responds in milliseconds.”
The perimeters of the reactors are lined with six-foot concrete walls that are two metres thick with the intent to stop radiation from escaping should something go wrong inside the reactor, says Saunders.
After the 2011 Fukushima incident in Japan — where a massive earthquake and tsunami killed thousands of people and destroyed a nuclear power plant — Emergency Management Ontario collaborated with Bruce Power to develop a multi-jurisdictional disaster response exercise to simulate severe weather incidents. From Oct. 15 to 19, 2012, more than 1,000 participants from 70 organizations and municipalities participated in “Huron Challenge – Trillium Resolve,” which simulated a tornado descending on the power plant and surrounding community. Bruce Power tested its new emergency management centre located off-site, as well as the on-site first responders and security personnel in its emergency and protective services division. Bruce Power has 400 employees in emergency services.
The biggest distinction between nuclear power plants and other industries is the amount of oversight they receive. Bruce Power has about eight people from CNSC that work on-site full time to monitor its work. Every two years, the World’s Association of Nuclear Operators spends two weeks on-site and the International Atomic Energy Agency occasionally visits the site as well, says Saunders.
The CNSC gives all nuclear operators a safety report card that is published on its website, so operator safety is very transparent, visual and in depth.
Because their operating licenses require adherence to strict safety standards, nuclear power plants deem safety as “number 1” and allot funds to major safety programs, says Shier. This helps make sure that safety is top of mind for workers as soon as they start in the industry.
“When you go into a nuclear plant, you’ll see the safety culture. People go about things safely: They’re wearing their PPE, they’re conscious of health and safety issues, if someone steps into an area they’ll tell you, ‘Don’t go over there.’ It’s an enshrined safety culture,” he says.
Bruce Power has a “non-incriminating culture” and is constantly reminding people to ask questions, not take shortcuts and stop work if they are unsure, says Saunders.
“We praise people who make those kinds of decisions,” he says.
Every quarter, the company conducts a safety culture panel that reviews OHS trends. Every three to four years it conducts a major safety culture assessment that surveys all staff members.
“That’s where we can pick out people’s attitudes,” says Saunders. “So if we find in there that somehow we’re driving a message that’s inappropriate, and that people are going in the wrong direction, we can do something to correct it.”
© Copyright Canadian Occupational Safety, Thomson Reuters Canada Limited. All rights reserved.