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Tritium Decontamination Techniques and Technology. C. A. Gentile, J. J. Parker D&D Lessons Learned Workshop June 25-26, 2002 PPPL. Oxidative Chemistry Employed for Tritium Removal. H2O2 (hydrogen peroxide) liquid phase O3 (ozone) gas phase Technology Overview

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tritium decontamination techniques and technology

Tritium Decontamination Techniques and Technology

C. A. Gentile, J. J. Parker

D&D Lessons Learned Workshop

June 25-26, 2002

PPPL

D&D Lessons Learned Workshop

oxidative chemistry employed for tritium removal
Oxidative Chemistry Employed for Tritium Removal
  • H2O2 (hydrogen peroxide) liquid phase
  • O3 (ozone) gas phase

Technology Overview

    • Reduce tritium surface (and bulk) contamination on various components and items
    • Remove contamination by chemically reacting elemental T to tritium oxide (purge reaction effluent to TCS or stack)
    • Control via implementation of specific concentrations, catalytic parameters, and/or process conditions

D&D Lessons Learned Workshop

slide3
Introduction
  • Expendable items de-tritiated to activity levels at or slightly above background level
  • Re-usable items de-tritiated to free release levels (< 1000dpm/100cm2, and for use in controlled areas)
  • Oxidative Tritium Decontamination System (OTDS) capital cost and operation cost is relatively low, compared to other decontamination methods

D&D Lessons Learned Workshop

slide4
Background
  • O3 and H2O2 decontamination processes both employ oxidative chemistry
  • Process was implemented on contaminated RF Feedthrough components (copper, stainless steel)
  • Post H2O2 process activity levels dropped significantly (< 1% initial activity)
  • No discernable surface regrowth was noted after approximate 8 month hold time

D&D Lessons Learned Workshop

slide5
Background

Stainless Steel RF Feedthrough Components

Copper Internal Conductor Component

D&D Lessons Learned Workshop

slide6
Background

D&D Lessons Learned Workshop

slide7
System Configurations

Oxidative Tritium Decontamination System

Rotary Stationary

D&D Lessons Learned Workshop

slide8
Rotary System Configuration

D&D Lessons Learned Workshop

slide9
Stationary System Configuration

D&D Lessons Learned Workshop

slide10
Piston-Cylinder Configuration

Vo = X

Co = [O3]

Vf = 0.5X

Cf = 2[O3]

uncompressed compressed

D&D Lessons Learned Workshop

slide11
Reaction Chemistry

D&D Lessons Learned Workshop

slide12
Reaction Chemistry
  • Secondary reactions (promote additional release of hydrogen isotopes)
    • oxidation of carbon via ozone and/or diatomic oxygen to yield CO2 (and CO)
    • reaction of nitrogen (if present in system) with tritium to yield tritiated ammonia
    • oxidative dissociation of polymer chains

D&D Lessons Learned Workshop

slide13
Reaction Chemistry
  • Required duration of O3 exposure dependant upon:
    • concentration of pure O3 in feed
    • residence time in reaction chamber
  • These parameters are controlled via the following:
    • concentration of diatomic oxygen in gaseous supply to ozone generator
    • volumetric flow rate (output) of ozone generator
    • volume of reaction chamber

D&D Lessons Learned Workshop

slide14
Reaction Chemistry
  • Desiccation/drying of feed supply
    • Lowers relative humidity within reaction chamber, thus facilitating evaporation of HTO (tritium oxide)
    • Reduces possibility of formation of hydroxyl radicals, which can hinder the primary reaction mechanism
  • Desiccation/drying of feed supply yields shorter system run-time

D&D Lessons Learned Workshop

slide15
Decomposition of Excess Ozone Following Oxidation Process in OTDS
  • HVAC ductwork, in most cases, is constructed of ferrous metal, which exhibits corrosion when exposed to strong oxidizing agents
  • Ozone will degrade polymer-composite seals present in HVAC systems
  • It is necessary to significantly reduce the release of ozone into these systems

D&D Lessons Learned Workshop

slide16
Decomposition of Excess Ozone Following Oxidation Process in OTDS
  • Thermal Decomposition
  • Activated Carbon Decomposition
  • Hopcalite Catalyst Decomposition

D&D Lessons Learned Workshop

slide17
Thermal Decomposition

Ozone must be held at temperatures exceeding 300 degrees Celsius for an approximate 3 second duration for adequate conversion to occur

D&D Lessons Learned Workshop

slide18
Activated Carbon Decomposition

Design of activated carbon bed must allow for an approximate 3 second residence time for adequate conversion to occur

D&D Lessons Learned Workshop

slide19
Hopcalite Catalyst Decomposition
  • MnO2 (manganese dioxide) based catalyst
  • Not consumed during ozone decomposition
  • Approximate 0.36-0.72 second residence time
  • >99% conversion of up to 120000 ppm ozone

D&D Lessons Learned Workshop

slide20
Efficient Removal of HTO
  • HTO formed via this reaction mechanism is not removed through chemical process
  • Majority of HTO remains as condensate on material surfaces
  • A physical process (i.e. evaporation) must be implemented to facilitate HTO removal

D&D Lessons Learned Workshop

slide21
Efficient Removal of HTO

D&D Lessons Learned Workshop

slide22
Results

D&D Lessons Learned Workshop

slide23
Results

D&D Lessons Learned Workshop

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