Simulation of Radiation Fields in the Point Lepreau NGS Fueling-Machine Vault


K. T. Tsang, C. R. Boss, G. Gomes, V. Krishnan


The CANDU® (CANadian Deuterium Uranium) is a registered trademark of Atomic Energy of Canada Limited (AECL). Point Lepreau nuclear generating station (PLGS) in the province of New Brunswick, Canada, has been operating since February 1983. Recently, New Brunswick Power initiated a study of the potential refurbishment of PLGS to extend plant operation for another 25 to 30 years beyond 2008. Refurbishment involves the replacement of the Zr/Nb pressure tubes in the reactor core. In addition, the feeder pipes that have experienced thinning due to flow-assisted corrosion will be replaced. As a result of the corrosion, activated corrosion product material is precipitated at different locations in the fuel channels, feeder pipes, and steam generators. Consequently, shutdown radiation fields in the fuelling-machine vault are dominated by the deposited activities, rather than by activation photons from reactor components. To ensure that workers receive the minimal amount of dose when replacing the channels and feeder piping, an assessment of the radiation fields at the reactor face is needed. The results of the assessment will allow the project to minimize the radiation field in the fuelling-machine vault. This paper uses a point-kernel calculation model, in combination with deposited activity data that are available from the plant to calculate the radiation field in the fuelling-machine vault. The verification of the simulation results against measured dose rates at PLGS is also presented.


This abstract was presented at the 35th Annual Midyear Meeting, "Decommissioning and Environmental Restoration", Poster Session, 2/17/2002 - 2/20/2002, held in Orlando, FL.

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