Application of the Terminal Solid Solubility (TSS) Tool ... · • On-site set-up, ADM/TSS training...

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GENERATING SUCCESS --- FOR 100 YEARS

Application of the Terminal Solid

Solubility (TSS) Tool for Fuel Channel

Inspection in Wolsong Unit 2

A. Wallace, K. Tashiro(Kinectrics Inc., Toronto ON Canada)

Kim, J-S(KHNP, Wolsong NPP 1, South Korea)



Outline

• Hydrogen in Pressure Tubes

• Introduction to the TSS Technology

• Past Operating Experience

• Kinectrics Improvements

• Wolsong Unit 2 Campaigns



Hydrogen in Pressure Tubes

• Hydrogen forms brittle precipitates in pressure tubes (PTs)

• Can threaten long-term PT integrity:

– DHC from notches

– Reduced toughness

– Blister formation

• [H]eq = [H]initial + [D]/2



0

20

40

60

80

100

120

140

160

0 1 2 3 4 5 6

Distance from inlet (m)

Hyd

rog

en

Eq

uiv

ale

nt

Co

ncen

tra

tio

n (

mg

/kg

)

Measured values at 12 o'clock

TSSD

CSA N285.8-05 limit

Pressure Tube Heq Profile

Surveillance Pressure Tube after >160k EFPH



What is TSS?

TSSd and TSSp curves provided CSA N285.8

0

50

100

150

200

250

300

350

0 10 20 30 40 50 60

[H]eq (mg/kg)

So

lvu

s T

em

pe

ratu

re (

oC

)

TSSd

TSSp

Hydrides Precipitated

Hydrogen in Solution

The TSS curves

indicate the

concentration of H

in solution that is in

equilibrium with Zr

hydride at a given

temperature for

both: • heating (TSSd,

dissolution temp), and;

• cooling (TSSp,

precipitation temp)



Basic Components of the TSS Tool

SERVICE CONNECTORS

EDDY CURRENT PROBE & THERMOCOUPLES

CENTERING MODULE TOOL SEALS INDUCTION HEATING COILS

INSULATION



Auxiliary Equipment

Pump Cart

Power Cart

In Vault Cart Control Rack



TSS Tool Advantages• The TSS Tool has several clear advantages

over scrape sampling:

– Reduced dose uptake to staff

– No material is removed from the PT inside surface

– No need to handle and ship samples for analysis

– Results available for review before tool comes off channel

– Bulk measurement, not affected by surface gradients

– Result is representative of both [H], Heq, and [D], deuterium concentration

– TSSd temperature values can be used directly in assessments



TSS Tool Limitations

– Cannot distinguish between [H] and [D]

– Additional design and assessment work is required to

justify heating the PT to temperatures greater than the

design registration temperature in the stress report

(~320oC)

– Required to measure expected TSSd values near End-of-Life

– Assessments have already been performed to support up to 350oC

– May be necessary to develop TSSd-based predictive

models

– May not be able to measure TSSd in new PTs with low

initial [H] for first few years until Heq builds up



TSS Tool Operation

1. The tool is inserted into a defueled pressure tube (PT) and positioned at the target measurement location

2. The seals are inflated to create a closed annular space

• Coolant continues to flow through the centre of the tool

3. N2 gas is injected to displace the D2O coolant from the annular region around the central body of the tool

4. The measurement probe head is extended so that the thermocouples contact the PT inside surface

5. Power is applied to the induction heaters on either side of the measurement probe head

6. A minimum of two and cooling cycles are applied and the temperature and resistivity are recorded for analysis



TSS Measurement

• TSS Tool identifies the temperature of hydride

dissolution (TTSSD) by measuring the pressure tube

resistivity (with eddy current techniques) through a

controlled heating cycle, and identifying the inflection

point in the Resistivity vs. Temperature curve.

• Pressure tube material resistivity can be described by

the following relationship:

• ρρρρT = ρρρρo (1 + αααα(T)) + ρρρρH CH(T)

11



TSS MeasurementMATHEMATICAL CONSTRUCT INTERSECTING LINES CONSTRUCT

BASE RESPONSE

FIRST DERIVATIVE

SECOND DERIVATIVE

Resistivity (V) vs.

Temperature (H)

plots.

Whereas DSC measures changes in heat flow associated with hydride dissolution and precipitation, the TSS Tool measures an inflection in the rate of change of

resistivity associated with changing hydrogen concentration in solution



Sample Data Analysis



Past Operating Experience

• TSS Used in 20 OPG and Bruce Power campaigns

• Significant Dose Savings (100 R?)

• What went wrong?

– Insufficient effort managing transition from scrape

• Outage pressure prevented scrape & TSS, repeats

– Insufficient system configuration control and QA

• Probe manufacturing problems

– Late recognition of the problems

• Inability to calibrate on CFTS



TSS Tool Validation

15



Surveillance PT Comparison

150

200

250

300

0 1 2 3 4 5 6 7

Axial Location (m)

DS

C T

SS

d (

oC

)

Inlet R/J (12:00)

12 o'clock

6 o'clock

Outlet R/J (12:00)

TSS Tool uncorrected

TSS Tool Empirically Corrected



Kinectrics Improvements to TSS Tool

• Following OPG’s decision to stop using the tool, Kinectrics negotiated the right to use/modify TSS for CANDU Fuel Channel inspections worldwide

• Obtained access to all equipment, data and procedures

• Implemented several improvements• Calibration & Test facility

• Probe fabrication and Induction Coil procedures

• Dedicated Umbilical Cabling and Tool Interface

• Improved seals and bladders

• Training and Procedures

• Successfully marketed TSS to KHNP

• Latest improvement is inboard RJ measurements and modelling



Wolsong Unit 2 TSS Scope Overview

• Definition of inspection scope and recommend fuel channel selection

• On-site set-up, ADM/TSS training and calibration

• Provide PB interface from TSS to ADM with new umbilical cable

• Operation and Interface with Delivery Machine

• In 2010, TSS measurements on 4 channels (BoT only)

• In 2013, TSS measurements on 10 channels in the BoT, including either 1 or 3 measurements near each rolled joint (180, 250, 360mm from the PT end)

• Analysis of results, preliminary & final reports

• Deuterium ingress modeling

• Provide support for regulatory communications



Calibration Facility

19



• Performed integrity assessment

– Wall thinning and creep in the RJ region not

sufficient to require irradiation strengthening to

be invoked in stress report

– Hence no concern about exceeding design

registration T, if necessary

• Used mock-up tests to demonstrate that surrounding FC components are not heated significantly when PT is heated to 350°C

Preparation for RJ Measurements



Preparation for RJ Measurements



In-Vault Operations• TSS Tool transferred into vault inside the ADM

• Instrumentation hooked up and tested, verified

• Attached to calibration facility and performed calibration

• ADM mounted to FM bridge

• 2010 4 BoT fuel channel TSS measurements(2 teams on 12h shifts)

• 2013 10 BoT fuel channel and inlet and outlet Inboard RJ TSS measurements

(2 teams on 12h shifts)

• Post-campaign calibration on calibration facility

• 100% of planned measurements achieved



On-channel Measurement

Example TSS Heating/Cooling Cycle

0

50

100

150

200

250

300

0 20 40 60 80 100 120

Elapsed time (min)

Pre

ss

ure

Tu

be

Te

mp

era

ture

(oC

)

Preconditioning Measurement #1 Measurement #2

Perform

Preliminary

Analysis

Option to abort second

measurement cycle



PT Offcut Measurements

• Offcut measurements were performed by Kinectrics

to establish the initial H for each tube inspected

• Critical to obtaining reasonable D estimates from

TSSd and Heq

• D = 2(Heq – Hinitial)

• In general, initial H was found to be 1 - 2 ppm

higher than the reported ingot analysis

– Likely due to 24h 400C steam autoclaving

25



W2 Offcut Initial Hydrogen

26



Scrape vs TSS DUR Comparison

27

Es

tim

ate

d H

eq

Up

tak

e R

ate

Estimated Coolant Temperature

2007

2010

2013



RJ and BoT TSSd ProfilesT

SS

d

Distance from PT Inlet End



RJ and BoT Concentration ProfilesH

yd

rog

en

Eq

uiv

ale

nt

Co

nc

en

tra

tio

n

Distance from PT Inlet End



Summary

• Tool and equipment performed well for two campaigns

• Pre-and post on-channel calibrations of 8 ppm successful

• 2013 campaign performed measurements in BoT and both

RJ regions in one visit (3 channels - 10 locations each)

• Valid measurements obtained at all BoT and near RJ

locations

• Inferred D values consistent with prior scrape and TSS data

• Kinectrics demonstrated its ability to execute an inspection

campaign in the field under a highly challenging timeline

• The TSS Tool has been re-established as a viable

inspection technology

Application of the Terminal Solid Solubility (TSS) Tool ... · • On-site set-up, ADM/TSS training...

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Transcript of Application of the Terminal Solid Solubility (TSS) Tool ... · • On-site set-up, ADM/TSS training...