An ab initio investigation of lead (II) complexes as possible corrosion products in a CANDU supercritical water-cooled reactor (SCWR)

Abstract

Supercritical Water Cooled Reactor (SCWR), direct-cycle pressure tube reactor, is the Generation IV conceptual design. SCWR operates at 25 MPa and 650 ºC and offers significant advances of sustainable energy production, safety, and proliferation resistance. Under extreme conditions, traces of heavy metals could dissolve from the construction material and form complexes with surrounding anions and deposit within reactor, causing corrosion. Lead is the metal of interest because it exists as an impurity within construction material and causes embrittlement. It is essential to predict and control water chemistry to ensure the sustainability of SCWR. Pressurized and heated solutions are challenging for experimental research; computational method becomes a key research tool. Comprehensive ab initio calculations were performed on lead (II) complexes containing water, chloride, hydroxide and ammonia ligands. Results compare favourably to literature data, where available. The best candidates for corrosion products are:[Pb(H[subscript 2]O)[subscript 8]] [superscript 2+]; [Pb(OH)[subscript 2] and [PbCl[subscript 2]] and their hydration products.