Decontamination, decommissioning and reutilisation (DD&R) of nuclear sites is fast becoming a major industry in its own right, and arguably, at present, the only growth area in the nuclear power business. The market for DD&R services and technology is at the moment dominated by the US. In particular the Department of Energy (DoE) nuclear complex, built up over the decades of the cold war, now has many sites which are no longer needed and require clean-up.

The American Nuclear Society’s second Topical Meeting on DD&R of Commercial and Government Facilities (Knoxville, 12-16 September) reflected the increasing importance of the field. Representatives of the nuclear industry throughout the world met to present new technologies and processes designed to address DD&R problems and to discuss the likely development of the market and its role within the wider nuclear industry.

The DoE, and the agencies that preceded it, constructed more than 20 000 facilities. Some 7000 of these now need deactivating and more than 700 require active decommissioning. To address these problems the DoE Office of Science and Technology (OST) runs the Deactivation and Decommissioning Focus Area (DDFA), one of the OST’s four major technology development areas. Its aim is to develop, demonstrate and implement suitable technologies; to do this the OST has developed the Large Scale Demonstration and Deployment Project, with the aim of sponsoring first time, full scale demonstrations of innovative technology.

“The major drivers for these technologies are the high safety and health risks associated with working in aged and contaminated facilities and the high costs associated with facility deactivation and decommissioning using currently available baseline technologies,” said Jerry Hyde of the DDFA based at the Federal Energy Technology Center at Morgantown, West Virginia.

The total DoE market for DD&R services is likely to be as much as $32 billion between now and 2070. Beyond this market is the less mature, but rapidly developing, demand for services to decommission privately owned nuclear power plants which have reached the end of their productive lives. Both sectors require innovation to reduce costs, improve efficiencies and ensure adequate worker protection, but a major difference between them is that while commercial plants have been legally obligated to build up decommissioning funds, the DoE complex is not so well prepared.

According to Carroll Eichhorn of Bartlett Decommissioning Services, who presented a paper on the problems associated with the decommissioning challenge, the failure of waste management in the US is going to cost the taxpayer around $50 billion. When this figure is combined with that for DoE decommissioning, the scale of the problem becomes apparent.

“As the public becomes more aware of the situation, they will be looking to a variety of sources for answers,” said Eichhorn. “Failure to provide effective planning for national D&D has frightening parallels to the savings and loan fiasco.”

Eichhorn argues that the fact that the government was found liable following the collapse of the Savings and Loans bank in the early 1990s has set a precedent in terms of liability which will mean the DoE is liable for the utilities’ costs for storing spent nuclear fuel, as utilities have long argued.

“The dollars are not as important as the impact on public opinion,” he said. “The public relations fiasco could affect us all.”

But instead of pulling together, Eichhorn argues the industry has broken into factions. He describes the industry response to the DD&R challenge so far as being dominated by “poor communication, confusion, procrastination, turf battles, finger pointing and litigation among potential partners”. The different partners include utilities, disposal contractors, regulators, Congress, the presidential administration and the DoE.

“We can learn a valuable lesson from the big three automakers, former near-monopolies who competed aggressively on all levels in the past,” argues Eichhorn. “They now share integrated safety management systems, environmental control strategies, and information in other areas of common interest… These joint efforts reduce costs for each automaker and provide a unified front when dealing with proposed regulations or legislation.”

The ANS DD&R conference is clearly an effort to address some of the issues Eichorn raises. There is a path forward and by minimising DD&R costs and risks while making substantial progress in addressing some of its problems, the nuclear industry may be able to improve its public perception and move towards the possibility of a new generation of plant in the US.

“The first step in this effort is to expedite information transfer by improving communication and expanding the decommissioning experience universe. Sharing successes and lessons learned in decommissioning, radioactive waste disposition and related areas will provide cost savings for plants in D&D, a life-cycle planning basis for operating plants and a developing model for future plants,” Eichorn said.

Addressing some of the issues Eichhorn raised, Katherine Yuracko and Bruce Tonn of the Oak Ridge National Laboratory, described the development of a conceptual design for a national information infrastructure to support life cycle analysis (LCA) for D&D decision-making .

The information infrastructure would take advantage of the opportunities presented by the World Wide Web to distribute high quality information cheaply and quickly. “While the World Wide Web appears to be spontaneously evolving through the efforts of millions of uncoordinated and unintegrated efforts, the tools and resources necessary to support D&D decision-making will generally not come into being without the concerted effort of the D&D community,” say the authors.

Yuracko and Tonn argue that by using an LCA to make decommissioning decisions, cost can be saved in the long term. Traditionally, cost-based decisions have been based on near-term criteria, which often fail to see the potential savings as well as environmental benefits and health and safety improvements that arise from longer term thinking.

“The process has been used to support decisions on disposition of metals from Building K-31 at the East Tennessee Technology Park in Oak Ridge,” say the authors. “As a result of a detailed LCA, DoE decided to recycle the metal rather than dispose of it. The resulting Three-Building D&D and Recycle Project is under way. This project alone is estimated to recycle more than 100 000 t of material, saving the DoE more than $55 million for the recyclable material and avoiding the transport of 5000 truckloads of metal across the country for disposal.”

This and other LCAs have helped the DoE make decisions which have lowered the cost of DD&R work to the US taxpayer and improved environmental quality.

An effective and comprehensive LCA system would take advantage of the potential of information technology which is changing the nature of information management. The Internet has great potential for DD&R activities which are international in scale but decentralised in operation. But to realise this potential, the DD&R community needs to provide time, resources and commitment, with people in the field providing analyses, data and names of experts in various areas. Those building life cycle analysis models would need to be committed to making the information available to users over the Internet.

“The scope of the national D&D problem, the size of the D&D community, and the stakes involved for the country are such that an investment in building the envisioned LCAs should be seriously considered,” conclude Yuracko and Tonn.

Demonstration projects

The OST development of the Large Scale Demonstration and Deployment Projects is aimed at addressing the issues raised by Eichhorn, Yuracko and Tonn. Jerry Hyde described the projects and the technologies being applied at each.

At the Los Alamos National Laboratory (LANL) the OST is developing a project to demonstrate “technologies for the characterisation, decontamination, dismantlement, size reduction, segregation, packaging, and preparation for disposal of transuranic waste”, said Hyde.

The LANL has 2400 m3 of transuranic waste and is likely to produce another

3000 m3. The DoE plans to reduce the waste’s volume by 75%.

One of the technologies being developed as part of the LANL project is the AeroGo Airlift Pallet System (AGAPS), which is designed to move and position reinforced plywood crates containing surplus plutonium glove boxes. The system involves placing inflatable ‘torus bags’ under each corner of the crate. Air escaping between the inflated bags and the floor lifts the crate 3 mm off the ground, so workers can move the crates easily. The system should provide easier handling, better positioning, reduced labour requirements, fewer risks from accidents and be quicker than the traditional wheel castor system.

Another of the OST demonstration projects involves the decommissioning of a tritium production facility at the DoE Mound Site at Miamisburg, Ohio. Technologies being developed there include the Lumi-Scint 1000 portable scintillation counter and the Waterworks Crystal SP-400 polymer absorbent.

The Lumi-Scint 1000 device is portable so it can be moved to field survey sites. An operator takes a 100 cm2 surface smear and places it in a vial containing a liquid scintillation ‘cocktail’. The Lumi-Scint 1000 can then take an immediate reading, removing the need to take the vial to a laboratory.

The Waterworks SP-400 is a polymer- based absorbent designed to solidify aqueous waste. It offers benefits over traditional solidification agents like cement including a a high liquid-to-absorber ratio, no need for mechanical mixing, little or no increase in waste volume and high retention in a gel-like material.

Other demonstration projects include decommissioning of the Chicago Pile (CP-5) so the facility can be released for unrestricted use; decommissioning of the Fernald, Ohio Plant One uranium processing facility; interim safe storage of the Hanford 105-C production reactor; and decommissioning of fuel storage canals and associated underwater and underground facilities at the Idaho National Engineering and Environmental Laboratory (INEEL).

At INEEL the technologies being developed to carry out the project include soft-sided waste containers; a remote underwater robotic crawler; an automatic locking scaffolding system; a robotic vacuum-deployed wall climber; and a lead paint analyser. According to Jerry Hyde, these technological innovations should reduce D&D unit costs by 25% as well as shortening D&D schedules.

The final OST demonstration site is at the 321-M fuel fabrication facility at Savannah River in South Carolina, where about

1200 g of highly enriched uranium remains in the ventilation ducts, process systems and other areas. By removing the HEU the DoE will be able to reduce long-term surveillance and maintenance costs, by placing the 321-M facility in a long term passive safe storage condition, requiring no maintenance and only annual surveillance inspections.

The technologies being developed at Savannah River as part of the demonstration project include: strippable paint coatings that remove contamination from walls and other surfaces; a size reduction deployment platform (SRDP) designed to cut up large pieces of contaminated equipment; an alpha electret ionisation chamber (EIC); and a long range alpha detection (LRAD) unit.

Six strippable coatings made from plastic membrane or polymers such as polyvinyl chloride, which can be applied to surfaces using standard painting equipment, have been developed by six separate companies. After 24 hours the coatings are peeled off, with the ‘paint’ chemically and physically trapping contaminants. The removed waste is in a solid form, making it easier to dispose of than the liquid waste created using traditional decontamination methods. The DoE is now evaluating each material in a preliminary assessment. The most effective will be used in large scale decommissioning of the entire 321-M area.

The SRDP has been made by Denver based Utility Engineering. It contains a hydraulic shear manufactured by Mega-Tech Services, based in Jamestown, North Carolina. The platform uses hydraulics to take the weight of the shear off the operator, with the aim of increasing production, improving safety and reducing operator fatigue. The platform can be positioned manually and can shear objects from 15 cm below floor level to nearly 5 m above, and can cut within 5 cm of a floor or wall. Another benefit is that by using the SRDP the need to use scaffolding in many circumstances is eliminated. The demonstration will compare the SRDP with the standard method using a hand-held shear and portable band saw.

The EIC, developed by RedElec, based in Frederick, Maryland, is designed to assess surface contamination levels in order to categorise different areas and then assess them for decontamination.

The EIC consists of a charged Teflon plate, the electret, and a plastic chamber that can conduct electricity. The electret is designed so that it can retain charge for extended periods. The electrets are placed on a contaminated surface; alpha particles enter the chamber, ionise the air within it and the ions are then attracted to the charged electric plate. This reduces the electret’s voltage, indicating the contamination level of the surface. By placing a number of the EICs in strategic places within a room, an indication of the contamination level can be established.

During the demonstration the Savannah River health physics personnel plan to compare the EIC technology with the traditional manual smear and probe technique. The DoE will then make an assessment based on speed, reliability and sensitivity. As the EIC can be placed in a location and then removed and reused, it is likely to offer benefits based on the ALARA principle.

The effectiveness of the LRAD, which has been developed by BNFL Instruments and trademarked as IonSens Monitor, has already been demonstrated. The IonSens Monitor measures alpha particle activity by detecting ionised air. Its benefit over traditional techniques is that it is designed to reach areas such as the internal surfaces of pipes. Such areas may be clean enough to be free-released, but establishing this using the traditional manual probe and smear method is labour intensive and costly.

During the demonstration, material whose radioactivity level was already known was used. Of 500 items tested, 300 were identified for free release. The material contained almost 250 kg of lead which could then be reused, offering a significant cost saving. An average measurement cycle for the IonSens system is six minutes; the demonstration suggests the system is faster than probe and smear for large items or many small items measured in a single batch. The old method may be more suitable for small items requiring individual assessment.

Russian technology

The international nature of the conference was reflected in an event organised by Foster Wheeler Environmental where engineers from Radon, the Russian scientific and industrial association, demonstrated the metal powder composition (MPC) technology it has developed for decontaminating radioactive surfaces and solidifying radioactive waste.

The MPC is a magnesium/aluminium based material with potassium nitrate added as an oxidiser, which burns at temperatures as high as 2000°C. In a contaminated area it can be used to extract radioactivity from concrete, metal or asphalt surfaces.

An operator covers the contaminated surface with the MPC to a thickness of 1-2 cm. The MPC is then ignited and it burns for up to 20 minutes. Radon claims metal and asphalt surfaces are totally decontaminated, with a 90% decontamination of concrete. With asphalt, decontamination takes place by removing the top few millimetres of the contaminated surface.

“Almost no radionuclides are released in off-gas,” said Vadim Tarasov, who presented the Radon technologies at DD&R. “No off-gas cleaning system is needed. Also, no harmful by-products are produced as a result of combustion.”

On asphalt surfaces MPC eliminates the need to excavate and dispose of the entire quantity of asphalt. On concrete and metal surfaces the contaminates are sorbed into the slag layer during the burning. The combusted MPC is much easier to dispose of than the concrete or metal.

Further uses of the MPC material include the incineration of mixed waste containing organic material. The MPC process is said to reduce off-gas release compared with traditional incineration techniques. MPC can also reduce the volume of ion-exchange resins and be part of a process of solidifying radioactive waste ash residue produced by traditional incineration techniques.

Tarasov also described a number of other technologies Radon has developed in the decommissioning field, which are currently being applied to D&D challenges in Russia and other countries of the Former Soviet Union.

Radon has developed a ‘cold crucible’ technique for waste vitrification. The cold crucible technique avoids problems associated with the use of a boron-silicate glass matrix, the technique which Radon had previously employed. These problems included corrosion of the refractory and high thermal inertia. Using an induction melter process, the cold crucible technique is based on the principle that the melt should not come into contact with the crucible walls. In October 1997 Radon completed construction of an industrial vitrification plant based on cold crucible technology. The plant has three lines each with a productivity of up to 25 kg/h of melting product. Radon has also designed a high productivity cold crucible with a productivity up to 500 kg / hour.

Another technology Radon has developed is electrokinetic remediation of contaminated soils. The aim of the technique is to avoid the need to remove and dispose of large quantities of contaminated soil. Tarasov described the two-step process Radon has developed:

“Representative contaminated soil samples are taken to a laboratory where a reagent is selected that will ionise or complex the contaminants present in the soil. The reagent is an environmentally safe chemical that can be added to the soil to preferentially ionise the contaminants of concern. Also the electrical parameters such as current, voltage and electrode spacing, required to cause the ionised contaminants to migrate are determined in the laboratory.

“The second phase of the process is carried out at the contaminated soil site. The ground is saturated with the selected reagent. Electrodes are placed into the soil at the required spacing and a current is applied. The ionised contaminates migrate to the electrodes and are collected over a period of days. The duration of the remediation depends on the desired degree of contaminant removal.”

Radon has applied this technology to contamination both in Russia and the US, including a contract with Lockheed Martin at the DoE’s K-25 facility at Oak Ridge, Tennessee. Here soil containing uranium was decontaminated, with a 90% removal rate. In Russia Radon achieved a 67% removal of caesium from an area of more than 70 m2.

Laboratory stage technology

Many other companies presented relevant technologies at different stages in the research and development process. Marc Hallada of the Schafer Corporation, described the potential of using a chemical oxygen-iodine laser in decommissioning work. Lasers have a particularly important application in cutting up large contaminated objects, but at present are limited by the power that can be applied through fibre optics to a remote environment. According to Hallada, the oxygen-iodine laser offers high enough power to cut 30 cm thick stainless steel at 2 cm a minute, three times the speed of CO2 lasers of comparable power.

Brian Davison, Tanya Kuritz and Catherine McKeown of the Oak Ridge National Laboratory presented work on an experimental study using aqueous biopolymer solutions to decontaminate metal surfaces. The biomedium is designed to solubilise heavy metals such as uranium.

Aka Finci of Mission Research Corporation, Daniel Stanfill of Detection Sciences and Larry Whitmill and Mark Kraft of LMITCO/INEEL described the possible use of electromagnetic radiography to establish what material lies buried at contaminated sites. The technique is particularly suited to establishing the chemical composition of contaminated sites.

Decommissioning is already big business, with significant growth over the next decade inevitable. With the resources available within the DoE complex and companies such as GTS Duratek, BNFL Inc, Foster Wheeler, Bechtel and Babcock & Wilcox competing for business and expertise, advance is rapid. Problems that appear today as almost insurmountable are likely, within a few years, to be well on the way to being addressed. Once the perception develops that dealing with contaminated nuclear facilities is possible, new opportunities for the nuclear industry may emerge throughout the world.