To win public support, the nuclear industry has to demonstrate that it is safe. However much one posts statistics on comparative accident rates between different industries, and however much one explains about nuclear power’s ability
to generate large-scale electricity capacity without carbon emissions, public concerns remain focussed on the issue of long-term disposal of radioactive waste. Decommissioning retiring facilities is key to dealing with this issue.
John Clarke, chief executive of the UK Nuclear Decommissioning Authority, memorably described decommissioning as: “Putting away your old toys before playing with new toys”, an image that any parent of young children can understand. And, as any parent with young children quickly comes to know, the unglamorous job of clearing up can be time- consuming and difficult to manage.
It’s possible to push an analogy too far, but the successful decommissioning of retired nuclear facilities is key to the future of the industry.
Gordon Dover has been with Bechtel for more than 30 years and is now vice president and director of project integration for Washington Closure Hanford. This limited liability company, owned by URS, Bechtel, and CH2M Hill, is completing a $2.8 billion environmental remediation and decommissioning project at the US Department of Energy’s Hanford Nuclear Reservation in Washington state, US. The project’s scope of work includes safely decommissioning 329 buildings, cleaning up 555 waste sites and burial grounds, placing two deactivated plutonium production reactors and one nuclear facility into interim safe storage, and disposing of more than 11 million tonnes of radioactive contaminated material.
Planning
The first stage of a decommissioning project is planning. According to Dover: “The main issues in the planning stage are deciding how to eliminate hazards, and how and where to safely dispose of the waste. A lot of detailed planning goes into determining the best way to identify, locate, and eliminate hazards.
“Examples of the hazards that have to be evaluated include removal of mercury thermometers, removal
of asbestos, dealing with spring-loaded mechanisms, paints, mixed chemicals and radwaste, along with managing electrical circuits.
“A complicating factor is that facilities undergoing decommissioning might easily be more than 50 years old, and details of the design may be missing. To make the work even harder, the facility may have been modified during operation, and details of the modification may not be available. An example of this might be that of spills being painted over, and the event not recorded. New facilities are designed with consideration for the expected method of decommissioning, which makes the decommissioning simpler when it becomes necessary. However, this is generally not the case for facilities currently approaching decommissioning.
“Walkthroughs of the facility are an important first stage in the planning and preparation. But there can sometimes be a discrepancy between the design plans of what a facility should be, and what it actually is. Other sources of information are required so the company will, for example, interview retired employees from the facility to get as much information as possible on the actual situation inside buildings and enclosures.”
In order to understand how best to plan decommissioning work, those involved in the planning need an understanding of the issues that can arise during the course of the project. Therefore it is valuable for planners to have practical experience of decommissioning work.
“After safety and quality, budget and schedule are key factors in any project. In commissioning nuclear facilities, it is generally the case that the dominant consideration of the latter two is schedule; an incomplete facility is not fulfilling its function, and the cost involved is not achieving a return. The situation is reversed for decommissioning work. In this case schedule is generally not a major issue, because the facility is not in operation, and a delay generally has little impact. Keeping control of costs becomes much more important because there will be no further return on investment from the facility, so cost overruns cannot be recouped.
On the spot
“Even though a great deal of effort is made during the planning stage, there will inevitably be occasions when the plan does not fit the reality. We believe that it is important that all the decommissioning operatives are comfortable when they come across anything that they are in any way unsure about. In that event they have to feel able to pause work in the
affected area, so that the discrepancy can be properly evaluated.
“This can result in delaying work to resolve issues that turn out to have been a matter of perception rather than requiring any changes to practice; but until that doubt is resolved, it has to be regarded as a potential issue.
“The principle that we apply in our work is that “Safest is fastest.” It is generally quicker to take care and time to get a task done correctly the first time, rather than to make a mistake, correct that mistake, and then carry out the correct procedure. This, of course, is a secondary consideration to the fact that when decommissioning a facility that has a mixture of hazards and radwaste, safety considerations are paramount.
“The consequence of the emphasis on safe working is that decommissioning work has very low rates of industrial accidents – considerably lower than comparable projects in other fields.
“An example of an unexpected situation that arose during decommissioning was the removal of a 900t reactor at Hanford. The plan had been to cut away the roof surround and framework, cut holes in the top structure of the reactor bio-shield, and lift the reactor out. Unfortunately, it turned out that the top of the bio-shield was not strong enough to allow a vertical lift of the mass.
“The solution developed was to work from underneath the reactor, cut away tubing attached to it, and build a platform which could be used to pull the reactor up. The planning and preparation for this took one and a half years; the actual lift removal of the reactor took around a week.”
This pattern of long periods of planning and preparation and internal working, followed by a much shorter period of removal of large structures, is fairly typical. Decommissioning work has to be carried out methodically, with careful planning and preparation to ensure that there is no need for last minute, hurried improvisation.
Doing the decommissioning
The nature of decommissioning work changes over the course of the project.
At the beginning, the emphasis is on carrying out lots of planning, targeted clean- up, and removing energy from the site. “One of the first actions is to cut off all power to and within the site, and install electrical systems and temporary lighting of your own. This ensures that removing structures will not cut into live power lines; it is possible that modifications to electrical systems in the facility have been made that have not been recorded, and cutting all power supplies preserves safety.
“Specific crews will conduct walkthroughs of the facility, and gather as much information as possible about it. Work will be carried out to remove such things as asbestos and movable hazards. These can be lengthy operations on large sites. Hanford, for example, covers 586 square miles and includes nine plutonium production reactors, five chemical processing plants, fuel manufacturing facilities, research labs and various support facilities.”
The end of the decommissioning work is straight deconstruction work.
Skill sets
“Bechtel employs building construction craftspeople and trains them in how to handle radioactive material and the necessary procedures for safe working. They are also taught how to keep work at a low hazard, how to undertake decontamination procedures, how to avoid over-exposure and how to package radwaste.
“The people employed are very skilled in what they do; it is astonishing what individuals can accomplish with, for example, a large excavator.
“Bechtel also employs radiation and hygiene specialists and waste management specialists to ensure safe working practises are used.”
There have been some concerns expressed over the possibility of a future skills shortage in building craftsmen. This is not an issue at the moment in the US, but it may become one within the next ten to 20 years. New people are coming into the industry, but not in sufficient numbers to replace those leaving. There is a reserve of highly skilled people in the sector, and good training and apprenticeships are available. In some countries, there is a demographic effect. In the UK, there is a bulge in the number of people in the industry approaching retirement age over the next five to 15 years, with a consequent loss of skills.
Safety issues
“The working philosophy at Bechtel Projects is that safe working is the most effective and quickest way to work. It is better to take the time to get everything correct the first time than it is to start too quickly, come across a problem, and have to backtrack and start over.
“One result of this philosophy is starting each working day with a discussion on that day’s work, with a focus on the safety issues involved. The work package for each task contains a section where the people undertaking the task must comment on it, and when the task is completed there is a debrief on the work. This debrief consists of the following:
- Plan
- Execution
- Lessons learned
- Improvements that can be made.
- How to repeat the exercise, but with greater safety.
“The feedback loop for constant improvement is very important, and to achieve effective feedback, the workforce must be confident that comments made will be considered by management and the experience incorporated into practice.
“No one gets penalised for pausing work due to uncertainty over how to proceed should a situation not covered in the daily briefing arise. Uncertainty in and of itself is a potential safety issue, and pausing to resolve that uncertainty ensures safety. Penalising workers for pausing if they have doubts over an issue can lead to unsafe operations being undertaken.
“We have a policy of integrated safety management, in which feedback is not merely accepted, but is encouraged. This can result in longer periods spent in planning and determining a course of action. But it also increases safety, and the probability that the best course of action will be initiated, saving time in the long run.
“You need to have the tools, both physical and mental, to do a safe and effective job.”
External feedback
Internal feedback within a company is relatively straightforward. Communication regarding best practice between companies is not as easy, but there are several large conferences held at regular intervals at which information is exchanged.
There are frequent meetings and discussions with contractors, and companies who compete for one contract can easily be working together on another.
