Tritium Activities at NSSI

C. R. Shmayda, W. T. Shmayda, J. Cruz

Tritium Focus Group

Oakridge, TN

14-17 May, 2018

Over 40 employees operate the facility

Process 700 tons of waste annually

Capacity for 3-4 M gallons of aqueous

hazardous waste

Handle 1500 sealed sources annually

The facility comprises 40,000 square feet

of building space on 5 acres of land

NSSI services a diverse customer base in

the government, industrial,

radiopharmaceutical, and education

sectors

NSSI is a waste handling and treatment facility operating since 1971

NSSI operates a 10,000 sqft Tritium Recovery Facility on site

Current Capabilities:

• Light Water

• Heavy Water

• Tritiated light ampules

• Tritiated metals

• Hydride Unloading

• Liquid Mixed Waste

• Gaseous Mixed Waste

NSSI Activities in 2018

System Project

Mixed Waste Oxidation System

Installed new Furnace with central injector and Slurry pot for deposits

Pump Permeation Tritium permeation through a WH700 roots blower

New Cryopump Design Measured:Capacity vs Fill PressurePump Speed vs Fill Pressure

Tritium Lights Recovery Low Pressure, High Temp ExpAtmospheric Pressure, High Temp Exp

Heavy Water Detritiation PEM cell, CECE and Fcell Update

Tritium from Mixed Waste is currently recycled using multiple systems

Mixed Waste

Transfer Station

Mixed Waste Oxidation

System (MWOS)

Liquid Phase Catalytic

Exchange (LPCE)

Electrolyzer

Combined Electrolysis and

Catalytic Exchange (CECE)Isotopic Separation

System (ISS)

Reuse

Unknown Constituents in the Mixed Waste caused significant deposits in the Furnace and Catalyst

Deposit Inside the Furnace Deposit Inside the Catalyst

Deposit On the Feed Nozzle

• Deposit over 3 month period with one

type of feed stock

• High pressure drop across furnace –

failure indicator

• Pushed catalyst into the water

scrubber

Replaced entire furnace with new Nozzle system and a “Slurry Pot”, Upgraded TC’s

• Commissioned with known T2 and

C-14 mix – good burn

• Need to open after 3 months to

inspect

Removable Tube in Tube

Floating Nozzle

Slurry

Pot

Heaters

Installed, no

Insulation

Insertion

TC

Measured HT and HTO permeation through WH700 Roots Blower at low partial pressure

HT

Bubbler

HTO

Bubbler

Catalyst

Flow Direction

Flow

Controller

Tritium

Monitor

Vacuum

Gauge

Tritium

Gas

Source

Air

Box

Nine experiments over 50 hours eachRuns 6 to 8 were the highest activity

Pressure Activity KF Flange Seal Calc T2 Perm Rate

676 Torr 11.3 Ci/m3 Organic 9.33 mCi/h

200 Torr 2.9 Ci/m3 Metal 3.27 mCi/h

676 Torr 6.3 Ci/m3 Metal 3.99 mCi/h

Additional runs required to determine the pressure

dependence on the permeation rate.

0 10 20 30 40 50 60

Time (h)

0

1

2

3

4

Ac

tivit

y (µ

Ci)

0.032

0.081

0.0007

Run 6: 676 Torr H2, 11.3 Ci/m

3

Run 7: 200 Torr H2, 2.94 Ci/m

3

Run 8: 676 Torr H2, 6.3 Ci/m

3

Run 9: 760 Torr He, 0 Ci/m3

Conclusions:- 10 hrs to attain steady state

permeation

- Replacing the organic seal with a

metal O-ring reduces permeation

- Background run (Helium only)

indicated there was no virtual leak

through body

Performance of a new cryopump design was measured

Process

Valves

LN Vent

LN

Supply

Electrical

feedthroughs

(TC’s, Heaters)Red = Heater

Blue = Liquid

Nitrogen

Grey = Process Line

(5A Molecular Sieve)

Thermocouples

Vacuum jacketed

dewar

0 2 4 6 8 10

Capacity (sL)

75

80

85

90

95

100

Qu

an

tity

Ab

so

rbe

d (

%)

Efficiency Dependence on Cryopump Capacity

3.85 sL

11.6 sL

Best Fit

Best Fit

Cryopump exhibits high capacity and pump speed

0 200 400 600 800 1000

Initial Fill Pressure

0

2

4

6

8

10

12

Ca

pa

cit

y (

sL

)

Cryopump Capacity dependence on the Initial Fill Pressure

3.85 sL

11.6 sL

Best Fit

Best Fit

Conclusions:- Pump capacity for H2 ~ 12 sL

- Pump speed is conductance

limited

- Pump speed does not depend

on the initial fill pressure

between 100 Torr and 800 Torr

0 0.5 1 1.5 2 2.5

Time (s)

10-2

10-1

100

No

rma

lize

d P

res

su

re

Tank Pressure versus Time

3.8 L tank evacuation

P initial: 100 Torr

P initial: 800 Torr

A low cost method to recycle tritium from tritium lights was explored: 1st exp: > 1,200 oC in vacuum

0

100

200

300

400

500

600

700

0

100

200

300

400

500

600

700

800

0.00 0.50 1.00 1.50 2.00 2.50P

ress

ure

(to

rr)

Tem

pe

ratu

re (

C)

Run Time (hrs)

Temperature Pressure

Evacuated Chamber

Gas Permeation as

low as 500 oC

Before After

Furnace

CoverConclusion:

- Fast but too violent

- Low temp permeation

more controlled

2nd exp: < 1,000 oC at one atmospheric with 1 sLPMargon purge into the MWOS

0

200

400

600

800

1000

1200

0

0.1

0.2

0.3

0.4

0.5

0.6

0.00 20.00 40.00 60.00 80.00 100.00

Tem

pe

ratu

re (

C)

Act

ivit

y (C

i/m

3)

Time (hrs)

Furnace Setup in Glovebox

Tritium Lights in 1” Tube

Conclusion:

- Slower but controlled, only T2

- Lights temp < Furnace temp

- Total of 29 Ci from 15 tubes,

various sizes, >15 yrs old

- 400 mCi tail end for 30 more hrs

- Need to open and inspect

- Next Step – 4”x 12” long furnace,

with internal TC’s∫ = 29 Ci

Heavy water CECE with PEM and fuel cell PFD

B_in

WaterTreatment

PEM Ecell

O2

Tank

O2

ScrubCol

LPCECol

O2

Cond

DTOTank

DTOB_out

D2

Cond

BPV

Fuel CellHPD2

LPD2O

HPPump

HPD2O

FCellCond

D2OB_out

Chill PH O2

N2

Vent

Sample

Update on the Build

Room extension for PEM nearly complete

PEM cell shipping

end of June

Fuel cell has been

tested off-line

Acknowledgments

Ivan Mateo Facility Technician – NSSI

Questions?