MATERIAL FOCUS


from mills that have the capability, experience and appropriate quality assurance procedures to adapt routine commercial production to the special needs of the nuclear industry. In addition, the stainless steel supplier


will source nickel ore from mines with naturally low levels of nickel and take special precautions during steel melting to prevent cross-contamination. Full traceability of the specialist material throughout the subsequent steel processing is vital and a high level of destructive and non-destructive testing is carried out to demonstrate critical material properties have been achieved. These special production


runs are disruptive for the mill and so come at a cost.


Q: Why does this lead to supply challenges? AB: Nuclear projects all have their own requirements around choice of alloy or grade and content of cobalt and sometimes other trace elements including boron, tantalum and phosphorous. For example, in France, the RCC-M code often specifies a maximum of 0.2 per cent cobalt, although more stringent requirements can be set. Material orders may be further


complicated when fabricators need this material in specific product forms and sizes, such as plate, sheet and pipe or tubing. When combined, these multiple


requirements can make it difficult to source suitable material. It’s possible that the right type of material is sitting in stock but in many cases, the tightly-defined specification may require a stainless steel producer to melt a special batch. This is a complex proposition that requires a good business case and a longer lead time. For example, when ordering


materials, a fabricator might need to buy 5, 10, or 20 tonnes of 316L steel


in a combination of plate, sheet, and tube. However, steel mills typically produce melts of 50 to 100 tonnes. So, if a fabricator orders, say, 20


tonnes of 316L with 0.2% cobalt, the steelmaker faces a dilemma. They could make a full batch, but they might not get more orders for the same 316L grade with up to 0.2% cobalt. They might face their cashflow being tied up in stock or selling the expensive low-cobalt variant at a loss to another industry. Meanwhile, the next nuclear project


might need grade 304 with up to 0.1% cobalt. In this case, the buyer might be happy to upgrade to the batch of 316L the steelmaker has in stock, but they may not be able to accept the higher cobalt content. Nuclear projects can create difficult


commercial decisions for a steelmaker. As a result, EPC contractors and fabricators may struggle to source materials at a reasonable price, especially for smaller projects or repairs.


Q: How can fabricators avoid these challenges? AB: Stainless steel plays a vital role in ensuring the long and safe operation of components in the nuclear industry. But when specifying this material, it’s worth


knowing the industry’s niche requirements can cause challenges in procurement. When working with customers in the


nuclear industry, I would recommend that fabricators should push project managers to release technical specifications early. This will enable them to explore availability of material with the right specification, at the right time. The more notice, the better. Another solution is aggregating together similar material needs across a project to fit the scale of bulk steelmaking. This can result in lower costs.


Q: Is this situation likely to change? AB: The future development of Small Modular Reactors (SMRs) could provide a solution to this procurement challenge. The key difference from traditional nuclear projects is that SMRs will be produced as modules in serial production runs. This will create predictable ongoing demand for low-cobalt stainless steels. As well as improving availability, this could also reduce costs and lead times. It might also influence the choice of


grade. It’s likely that the same grades of 304, 316 and their variants will be used. However, small and micro modular


reactors may benefit from other grades. For example, the grade LDX2101 has twice the strength and similar corrosion resistance to 316L. It has been used to produce steel-concrete sandwich panels in mechanical equipment modules for the AP1000 plant design and could be used to fabricate long-lasting structural steelwork. Ultimately, the nuclear industry


requires special care and attention to ensure the highest quality. Fabricators and materials suppliers should work together closely for maximum success. www.outokumpu.com


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