Hanford Advisory Board Jeff Lyon, Nuclear Waste Program Washington - - PowerPoint PPT Presentation

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Hanford Advisory Board Jeff Lyon, Nuclear Waste Program Washington State Department of Ecology April 10, 2013 Six Tanks of Current Concern Summary Information Supernatant Maximum Salt Cake Drainable Capacity Volume Volume Liquids

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SLIDE 1

Hanford Advisory Board

Jeff Lyon, Nuclear Waste Program

Washington State Department of Ecology

April 10, 2013

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SLIDE 2

Six Tanks of Current Concern

Summary Information

Maximum Capacity Sludge Volume Salt Cake Volume Supernatant Drainable Liquids

T

  • 111

530 kgal 447 kgal 38 kgal

B-203

55 kgal 49 kgal 1 kgal 5 kgal

B-204

55 kgal 49 kgal 1 kgal 5 kgal

T

  • 203

55 kgal 36 kgal 5 kgal

T

  • 204

55 kgal 36 kgal 5 kgal

TY

  • 105

758 kgal 231 kgal 12 kgal

None of these tanks have elevated temperatures. Waste temperatures vary from 50 F to 75F.

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SLIDE 3

From PNNL-14221 3

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SLIDE 4

This plot shows that the majority of the waste in T

  • 111 is water. This data was
  • btained by heating core

samples to 300 C. Most of this water does not appear to be drainable water but rather is an integral part of the sludge. Other TRU waste has similar water content.

From PNNL-14221

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SLIDE 5

Six Tanks of Current Concern

  • T
  • 111, B-203, B-204, and TY-105 were already

initially declared assumed leakers in 1977 to 1984

  • T
  • 111, B-203, B-204, T
  • 203, and T
  • 204 may be

determined to be TRU tanks

  • All six tanks were declared inactive by 1977
  • All six tanks were Interim Stabilized by 1995
  • T
  • 111 and TY-105 are 75 feet in diameter
  • B-203, B-204, T
  • 203, and T
  • 204 are 20 feet in

diameter

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SLIDE 6

Single-Shell Tank Interim Stabilization

  • It is the drainable liquids in the tanks that can

leak through the liner and get to the soil.

  • All single-shell tanks have had as much of their

pumpable liquids removed as was practicable.

  • The majority of the Interim Stabilization

program was conducted between 1978 and 2004.

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SLIDE 7

Inventory of Tc-99 and Nitrate

  • 0.2

0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8

  • 50

50 100 150 200 250 300 350 NO3 Inventory (kg) Millions Tc-99 Inventory (Ci)

Bubble size represents Total Drainable Liquid Assumed Leaker SSTs (Excludes C Farm) T-111 TY-105

B-203 B-204 T-203, T-204

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SLIDE 8

Tc-99 Releases

BY cribs and trenches TX tank farm T tank farm SX tank farm B tank farm BX cribs and trenches C tank farm BX tank farm S tank farm U tank farm TY tank farm BY tank farm TY cribs and trenches TX cribs and trenches A tank farm T cribs and trenches B cribs and trenches AX tank farm

T-Farm 67.4 Ci of Tc-99 300 gallon leak of T-111 sludge = 0.01 Ci of TC-99 BY Cribs and Trenches TX Tank Farm SX Tank Farm

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SLIDE 9

T111 9

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SLIDE 10

Plan View of T

  • 111

ENRAF LOW Video Access 10

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SLIDE 11

In Tank Monitoring

  • Surface level in all single-shell tanks
  • Interstitial liquid level in 80 single-shell tanks
  • Infrequent visual inspections

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SLIDE 12

Single-Shell Surface Level Monitoring

ENRAF sensor attaches to riser above ground and detects the surface by monitoring tension in cable as plummet is lowered. ENRAF readings are normally collected once per day for the vast majority of the single-shell tanks. Image in T

  • 111 from approximately 60 feet

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SLIDE 13

Single-Shell Tank Interstitial Liquid Level Monitoring

  • A Liquid Observation Well (LOW) is a fiberglass,

plastic, or metal tube capped on the bottom to keep the inside dry

  • The LOW extends from a riser above ground to

near the bottom of the tank

  • A neutron probe is lowered through the LOW and

location of the liquid is determined by the change in the response due to the hydrogen in liquid/water

  • LOW readings are normally collected on a monthly

to quarterly cycle

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SLIDE 14

Image of T

  • 111 Waste Surface Showing Shallow Pool
  • f Liquid Around Central Salt Well

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SLIDE 15

Waste Surface in T

  • 111

Thermocouple 15

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SLIDE 16

150 155 160 165 170 175 180 185 190 195 200 Dec-71 Dec-75 Dec-79 Nov-83 Nov-87 Nov-91 Nov-95 Nov-99 Nov-03 Nov-07 Nov-11 Nov-15 Nov-19 Instrument Reading, inches

T

  • 111 Monitoring Data

LOW Surface Declared Leaking Tank Declared Leaking Tank

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SLIDE 17

Interim Stabilization Offset

  • The following data includes a data set that

reflects an increase of 5.7 inches in the ENRAF data for the time after the Interim Stabilization was completed.

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SLIDE 18

165 167 169 171 173 175 177 179 Dec-71 Dec-75 Dec-79 Nov-83 Nov-87 Nov-91 Nov-95 Nov-99 Nov-03 Nov-07 Nov-11 Nov-15 Nov-19 Instrument Reading, inches

T

  • 111 Monitoring Data

Reference Offset IS Offset Linear Fit

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SLIDE 19

T

  • 111 LOW and ENRAF Data Trends
  • LOW and ENRAF data have been tracking each other

with an offset of 3.5 inches

  • ENRAF data shows annual fluctuations of

approximately one-eighth of an inch

  • Current surface level is approximately where it was

after tank was taken out of service (when consideration is given to liquids removed during interim stabilization)

  • If one uses the last two months of level data to

calculate a level decrease rate, the rate equates to about 4,000 gallons per year if it is caused by a leak.

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SLIDE 20

50 100 150 200 250 300 Dec-79 Dec-81 Dec-83 Dec-85 Dec-87 Dec-89 Dec-91 Dec-93 Dec-95 Dec-97 Dec-99 Dec-01 Dec-03 Dec-05 Dec-07 Dec-09 Dec-11 Dec-13 Dec-15 Instrument Reading, inches

200 Series Tanks Surface Levels

B-203 B-204 T-204 T-203

Step changes in surface level data are due to change from manual tape to ENRAF 20

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SLIDE 21
  • 1.2
  • 1
  • 0.8
  • 0.6
  • 0.4
  • 0.2

0.2 Dec-01 Dec-02 Dec-03 Dec-04 Dec-05 Dec-06 Dec-07 Dec-08 Dec-09 Dec-10 Dec-11 Dec-12 Dec-13 Change in Level, inches

B-203, B204, T-203, and T-204 ENRAF Data Trends

Changes in surface levels since 2002 10 to 14 gallons per year

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SLIDE 22

50 55 60 65 70 75 Dec-01 Dec-02 Dec-03 Dec-04 Dec-05 Dec-06 Dec-07 Dec-08 Dec-09 Dec-10 Dec-11 Dec-12 Dec-13 Temperature, F

T

  • 203

Thermocouple #11 T emperature

Similar range for B-203, B-204, and T-204

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SLIDE 23

200 Series Tanks

  • Tanks B-203, B-204, T
  • 203, and T
  • 204 all show very

similar data trends over the past 10 years. Periodic annual fluctuations of about the same magnitude are visible for all four tanks, and the rate of decrease in level is almost identical for all four tanks.

  • Tanks B-203 and B-204 are known gas-generating tanks.

The manual ventilation valves are checked weekly to assure they are opened due to gas buildup concerns.

  • Seems too coincidental that all four tank behaviors

have such similar features.

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SLIDE 24

10 20 30 40 50 60 70 80 90 100 Dec-79 Dec-81 Dec-83 Dec-85 Dec-87 Dec-89 Dec-91 Dec-93 Dec-95 Dec-97 Dec-99 Dec-01 Dec-03 Dec-05 Dec-07 Dec-09 Dec-11 Dec-13 Dec-15 Instrument Reading, inches

TY-105 Monitoring Data

Surface Level

LOW- Interstitial Liquid

LOW Installation

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SLIDE 25

60 65 70 75 80 85 Dec-01 Dec-02 Dec-03 Dec-04 Dec-05 Dec-06 Dec-07 Dec-08 Dec-09 Dec-10 Dec-11 Dec-12 Dec-13 Instrument Reading, inches

TY-105 ENRAF and LOW Data

Surface Level LOW - Interstitial Liquid Level

Level drop indicates a rate of approximately 0.3 inches per year for both the surface and interstitial liquids. This might imply 1100 gallons per year compared to the 180 gallon per day leak rate in 1960.

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SLIDE 26

Possible Causes of Level Increases in Single-Shell Tanks

  • Intrusion of atmospheric water
  • In-flow of waste (however, all inlet lines to

single-shell tanks are plugged or capped)

  • Gas generation in the waste due to radiolysis
  • r chemical processes. Many sludge containing

tanks have such gas generation. SY-101, the “burping tank” had significant increases and decreases in surface level due to retained gas.

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SLIDE 27

Possible Causes of Level Decreases in Single-Shell Tanks

  • Breach of the carbon steel liner due to corrosion or other

causes and drainable liquids leaving the tank. This is the most likely cause of new tank leaks.

  • Breach of the carbon steel liner due to failure caused by high
  • temperature. Many previous leaks were caused by this

problem.

  • “Reopening” a leak that had “sealed” itself.
  • Evaporation of the water or other liquids in the waste.
  • Release of previously trapped gases from the waste.

Historically, gas generation and release have been associated with sludge waste. Retained gas is currently a concern for some double-shell tanks.

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SLIDE 28

Hypothetical Case for Gas Retention

  • All of the six tanks considered here are sludge

containing and each shows periodic, annual fluctuations in the surface level corresponding with tank temperature fluctuations. This could be due to expansion/contraction of bubbles.

  • The surface of T
  • 111 shows pits consistent with the

escape of gas bubbles.

  • Tanks T
  • 111 and TY
  • 105 show the surface and

interstitial liquid levels changing at the same rates. It is expected that liquids draining from the tanks would lower the interstitial liquid level much faster than the free surface.

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SLIDE 29

Summary

  • The available data clearly shows changes in the

monitoring data for the waste levels in these tanks.

  • Evaporation and gas release may explain at least

some of the level changes.

  • We do not know with certainty how fast these

tanks might be leaking – further analysis and monitoring is required.

  • Steps to reduce the adverse impact of possible

leaks should be undertaken.

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