Integrated Head Assembly

ADVENT has designed advanced optimized reactor head components for new as well as existing nuclear plants within and outside the USA. Plant outage time and dose savings are achieved by a reduction in downtime, manpower, and radiation doses, and by an increase in reliability.


ADVENT’s effort to design reactor vessel head appendages to promote savings can be applied to all existing Westinghouse, Combustion Engineering, and Babcock & Wilcox based Pressurized Water Reactor (PWR) operating plants. The basic concept of integrating all the removable upper reactor vessel head components into one removable structure is the object of these designs. For PWR operating plants, the objective is to substitute the massive concrete missile shield with a compact integral steel missile shield, to substitute the large cooling ducting and fans with a compact integral set of ducts and fans and to provide a convenient place to disconnect and reconnect the control rod drive mechanism (CRDM) cable assemblies. In addition, the design objective is to incorporate the lifting tripod as a permanent attachment to the top of the assembly.
To minimize the operational steps, down- time, radiation exposure and ultimately the outage costs, various new designs have been proposed by different reactor vessel manufacturers. One of the new designs includes developing an integrated head assembly in a modular form that can be detached from the reactor vessel in much fewer steps than identified above.


Functional Description

The integrated head assembly (IHA) is a mechanical assembly of various components required to provide cooling of the CRDM, radiation shielding for the CRDM, and the duct work for the air cooling system. All these components are assembled with the reactor vessel head into a single assembly that can be lifted in one lift and moved to the storage stand as a single structure during refueling. The IHA provides the ability to disconnect the head area cables, the head vent piping, and other instrumentation lines in one step. The IHA provides an interface between the containment polar crane and the reactor vessel head.


Some of the integral features of the IHA are as follows:

  • New Missile Shield
  • CRDM Cooling System
  • Head Area Cable System
  • Head Lifting Frame
  • CRDM Cooling Fans
  • CRDM Seismic Support
  • Cable Bridge
  • Reactor Head Vent Piping
  • Design, Fabrication and Installation Experience


Over the past 10 years, Advent has designed and supported fabrication and installation at the following nuclear plants:

  • Turkey Point 3 & 4
  • Salem 1 & 2
  • ANO 1
  • St.Lucie 1
  • DC Cook 1 & 2
  • St.Lucie 2
  • Diablo Canyon 1 & 2
  • Callaway 1
  • Davis-Besse 1


Implementation of the IHA into the existing operating plants provides the following advantages:

  • Reduced Polar Crane Usage
  • Lay down Space Optimization
  • Optimized Head Area Cables Routing and easy Accessibility
  • Increased Personnel Safety
  • Increased Dose Reduction
  • Improved Initial Preparation for Refueling


Advent has been awarded three (3) patents for One-Part IHA and one (1) Patent for Two-Part IHA in the USA. (Patent #’s US6456066; US6618460; US7139359; US7567645).



  • Comments from NRC at the Exit Meeting at Turkey Point 3 RVCH Replacement Project:
  • Best design of an IHA he has seen, and will benefit future outage ease of maintenance and dose reduction. This project is a new benchmark for the industry.
  • Nuclear Energy Institute (NEI) Top Industry Practice (TIP) Award:
  • FPL won a TIP award for the Design and Implementation of the Integrated Head Assembly at Turkey Point.
  • PSEG won a TIP Award for the Design and Implementation of the Integrated Head Assembly at Salem
  • Message from Salem Management:
  • 1R17 Refueling Outage completed in 25 days and 6 hours – Shortest Refueling outage at Salem
  • World record for Shortest reactor Head Replacement Outage (IHA installation included)