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Noble Metals Sampling

A Proven Method

The RSI noble metals corrosion deposit sampling system is state-of-the-art equipment based on fuel deposit sampling technology that has been used for more than 25 years.

Unique Features

Some of the unique features of the RSI noble metals sampler are:

  • Automated Sample Line Flush
  • "Single Motion" Sample Removal
  • Remote Control for Minimum Operator Exposure
  • "Adjustable" for Various Sample Types and Designs
  • Optional Sampler Heads for Other Sampling Geometries

Description

  • Compact Sampling Module
  • Microprocessor Controlled Sample Collection
  • Rapid Sampling Sequence
  • Calibrated Telescopic Extension Arm
  • Large Diameter Sample Filter

Introduction

The majority of domestic boiling water reactor (BWR) plants have implemented classic Noble Metals Chemical Addition (NMCA) or have transitioned to Online NobleChem (OLNC�). Noble metals deposited on reactor internal components are believed to deplete over time due to mechanical shear forces from fluid flow passing over the surface(s). The need to re-apply noble metals is currently based on depletion rates of pre-oxidized stainless steel coupons located in a Mitigation Monitoring System (MMS) or durability monitor (DM). Coupons are periodically removed from the MMS or DM by the utility and sent to an off-site laboratory for noble metals analysis. The MMS is installed in a side-stream of the reactor water cleanup (RWCU) piping and there is speculation as to the representation of the sample point at limiting noble metals conditions.

Background

The amount of noble metals deposited on the deposition monitor and durability monitor has varied widely during NMCA. Minor changes in reactor coolant pH and/or temperature result in different deposition rates. Perry Station chose not to install the MMS or DM in lieu of a reactor component sampling and analysis program.

Sample Campaigns Performed:

PERRY Station - each outage starting with RF09, RF10, RF11, RF12 and RF13 (April 2011)

  • Fuel Channels
  • Lifting Bale
  • Surveillance Coupons

COLUMBIA Generating Station - during RF19 and RF20 (April 2011)

  • Direct sampling of the core shroud

LaSALLE County Generating Station (June 2004)

  • Jet Pump Beams
  • Shroud Head Bolts
  • LPRM Tubes
  • Lifting Bale Handles
  • Core Shroud - each refuel outage since 2014

TVA BROWNS FERRY Station

  • Surveillance Coupons (March 2005, March 2007)

Application

BWR's with no durability monitor in service or plants with low confidence (large variability) in the data generated using the MMS. This process also saves on worker exposure by eliminating entries into high radiation areas for Mitigation and Monitoring System (MMS) coupon changeout.