V. Balasubramaniyan

Estimation of Spring-Back of Single Torus Inner Vessel Sector by Finite Element Analysis

Inner vessel in reactor assembly of sodium cooled fast reactor separates hot and cold pool sodium. The shape of inner vessel is optimized with reduced upper & lower shell diameters and toroidal redan for future Fast Breeder Reactor (FBR). This results in higher buckling strength and reduced thickness and hence reduced weight. To achieve the intricate toroidal shape with specified dimensional tolerances, a comprehensive technology development exercise was carried out successfully for the manufacture of inner vessel 30° sector. The achieved profile of the redan meets the specified dimensions and other design requirements. Spring-back observed in the sector was small. To verify the developmental exercise results, a finite element analysis (FEA) of forming of inner vessel sector was performed on finite element software ABAQUS. In this paper, FEA results and spring back are discussed. Spring back assessed is maximum at the center and relatively lower towards the edges for the redan with the chosen radius of 5980 mm.

Design Improvement Studies for Future SFR

Prototype Fast Breeder Reactor (PFBR), a 500 MWe, (U-Pu)O2 fuelled, sodium cooled, pool type fast reactor, is in advanced stage of construction at Kalpakkam, India. Based on the experience gained during the design, manufacture and erection of various reactor components of PFBR, it is planned to construct Sodium cooled Fast Reactors (SFR) by adopting twin unit (2×500 MWe reactors) concept. The future Fast Breeder Reactor (FBR) – 1 & 2 have three main heat transport circuits, namely primary sodium, secondary sodium and steam-water systems. All the reactor internals including core and primary heat transport circuit systems are contained in a single vessel called main vessel and it is closed with top shield. Reactor assembly forms the heart of the Nuclear Steam Supply System. A detailed and exhaustive design / optimisation exercise was initiated towards improving the economic competitiveness and enhancing the safety of future FBRs. It is observed that the overall dimensions of the reactor assembly contribute immensely to the capital cost. In this context, detailed studies were carried out towards optimizing the overall dimensions of the reactor assembly. Further, the reactor assembly design in particular has been engineered to favour manufacture of integrated assembly and erection of the same, as a single unit, in reactor vault to reduce construction time. Various activities undertaken towards technology development of critical components have enhanced the confidence level in the improved design concepts and reducing time for manufacture and erection.In addition to the reactor assembly, specific improvements have been made in decay heat removal systems and sodium purification system. The layout incorporates a twin unit concept in which the ex-vessel fuel handling system and fuel storage building are shared. This paper discusses the basis for undertaking the review exercise and experience gained during construction of PFBR and highlights the design studies and technology development carried out for future SFR.© 2014 ASME