Reprocessing metallic radioactive waste: the "good" kind of nuclear meltdown

By Michael Trovant |

Imagine a process specifically designed to meltdown radioactive material. Yes, intentionally, and as an integral part of the nuclear industry where most professionals devote their entire careers to preventing such an occurrence. Seem far-fetched? Well, when it comes to handling the radioactive waste associated with metallic scrap, the stigma may be blinding us from recognizing what could be the best solution.

Old-school pyrometallurgical processing technologies have been used for decades in the metals industry for controlled melting work. Now these processes are providing an alternative way to manage the coming surge of metallic radioactive waste.

In North America, the nuclear industry deals with most of its waste by burying it, storing it or occasionally reusing it. But for some time, Europe in particular has been handling decontamination and volume-reduction issues by melting low (LLW) and intermediate-level (ILW) radioactive waste. The practice has been largely dismissed here for a variety of political, social, and economic reasons.

But times are changing. Both North American and global inventories of metallic LLW and ILW are expected to increase dramatically over the next decade. This coincides with the large number of nuclear facilities that are being scheduled for decommissioning. It’s estimated that worldwide, only 13 of the hundred commercial plants that have already shut down are fully decommissioned. Another hundred plants are slated to close by 2025. And as much as 13 per cent of the steel in a decommissioned nuclear facility (roughly 1,000 m3 for a 1,000 MW facility) will be of the LLW variety.

As well as this decommissioning activity, a confluence of factors—the desire to minimize radioactive waste inventories, the limited availability of geologically stable repository sites in many regions, and the priority given to high-level waste for burial and storage—could lead to a re-evaluation of current industry practice.

Melting metal to extract radioactive waste is an environmentally friendly, sustainable technology. In fact, it’s the last of the Three R’s (Reduce, Reuse, Recycle) of good conservation strategy.

The process works like this. Contaminated scrap is melted and held in a liquid state for a specific period of time. Gravity allows most of the radioactive material to separate out of the melt. The metal is then cast into ingots of cleaned material. Most of the radioactive material reports to a small volume of slag that’s generated during melting. This is handled separately.

The exhaust from the furnace must also be treated. But here too, we can borrow specific gas-quality control technologies that were originally developed for the smelting industry. They’re ideal for this duty. Often, the metal is sufficiently decontaminated at this point to allow it to be reused. Even when this isn’t possible and burial proves necessary, the total volume is much less than that of the original scrap. This is a significant improvement and a nod to the first R of conservation, Reduce.

No, volume reduction doesn’t match recycling for environmental kindliness. But it does uphold another fundamental tenet of the nuclear industry: reducing waste volumes where economically viable, consistent with as-low-as-reasonably-achievable (ALARA) protocols.

The marriage of nuclear practice and pyrometallurgical processing will surely make for strange bedfellows. Few organizations will have the combined skill sets and necessary experience to design and engineer the facilities this practice will need. But that doesn’t mean there won’t be opportunities.

Today, working with some of our existing clients, Hatch is pioneering next-generation technologies to enhance metal cleanliness and minimize operator exposure. In fact, some of the technologies we’re developing may prove to be effective in major clean-up efforts such as Fukushima. Many of these systems, which have been developed in-house over the last few years, will push the perception of “reasonably” in ALARA to new levels.

When burying metallic scrap is no longer North America’s primary approach to managing it, producers will need other proven solutions. They won’t have the luxury of initiating time-consuming and costly research and development. Shipping huge quantities of radioactive scrap to Europe or Japan for processing won’t be a viable option, especially when those regions will be struggling to deal with their own surges in waste.

Hatch will be ready, able to service this market with engineered systems and optimized equipment designs that can be rapidly implemented for these specialty facilities.