Primary Heat Transport System Headers

  •    NPCIL
  •      GHAVP 1&2, Haryana
  •      16
  •     Nuclear Division


The Reactor Header Assemblies form part of two independent and parallel coolant loops of the Primary Heat Transport System for 700 MWe PHWR. The process fluid is re-circulating heavy water which extracts heat from the reactor fuel and raises steam in the steam generators for the turbine. Each header is a single piece of seamless construction, with integral nozzles.

Construction details

Materials: Forgings of SA350 Gr LF2


  • Overall length of each header: 15m
  • Outlet header: 508 mm OD, 65 mm thk
  • Inlet header: 457 mm OD, 65 mm thk

Critical aspects

  • Design pressure: 126 kg/cm2(g)
  • Design temperature: 326ºC
  • Hydro Test Pressure: 158 kg/cm2(g)
  • Helium Leak Test : Acceptable leak rate 1.0 x 10-6 STD. cc/sec