Session 14 NDA technique used at a Typical NPP

IAEA International Atomic Energy Agency

Session 14

NDA technique used

at a Typical NPP Aleksandr KULKO

Bushehr NPP Facility Officer

Division of Operations B

National Training Course on

Nuclear Material Accounting and Reporting 23-27 August, 2014, Tehran, Iran

IAEA NTC on NMA&R Iran-2014/Sess. 1/Sess. 14 Page 2

Outline

• Equipment Categories

• Physical Principles

• Measurement of Uranium

• Measurement of Plutonium

• Measurement of Spent Fuel

• Summary


Equipment Categories

• Authorized equipment

• Over 60 types of NDA equipment

• Portable

• Transportable

• Facility installed

• Equipment under evaluation

• Equipment being developed


Physical Principles

Nuclear Techniques:

Detection of Nuclear Radiation : Gamma rays, X-

rays, Neutrons

Physical Techniques:

Measurement of: Weight, Thickness, Heat and

Light Emission


U-235 Measurement

1. Gamma Spectrometry:

• Low and Medium Resolution Spectrometry:

Hand held Assay Probe (HM-5)

Mini Multi-channel Analyzer (MMCA)

Inspector 2000 Multi-channel Analyzer (IMCA) with NaI,

CdZnTe detectors

• High Resolution Spectrometry:

MMCA, IMCA with Ge detector

ISOCS – In-Situ Object Counting System

2. Active Neutron Coincidence Counting:

Uranium Neutron Coincidence Collar (UNCL)

Active Well Coincidence Counter (AWCC)

3. Physical Methods:

Load Cell Based System (LCBS)

Ultrasonic Thickness Gauge (ULTG)


Portable IMCA with NaI Detector IMCN

Material: Uranium

Technique: Low resolution

gamma-ray spectrometry

Purpose: 235U Enrichment

Detector: NaI


Typical high enriched uranium

spectrum with NaI

Uncalibrated channel number

Nu

mb

er o

f co

un

ts

0

2000

4000

6000

8000

10000

12000

14000

160001

27

53

79

10

5

13

1

15

7

18

3

20

9

23

5

26

1

28

7

31

3

33

9

36

5

39

1

41

7

44

3

46

9

49

5

Complex of peaks

dominated by 92.6

kev gamma 186 keV peak for

U-235


How the spectrum changes with

changes in enrichment

Uncalibrated channel number for PMCA

Num

ber

of

counts

0

2000

4000

6000

8000

10000

12000

1

37

73

109

145

181

217

253

289

325

361

397

433

469

505

Complex of gamma

and x-rays

dominated by 92.6

keV gamma

186 keV peak for U-

235

5% Enriched U

2% Enriched U

1% Enriched U

Natural U (0.71%)

Depleted U (0.37%)


High-Enriched Uranium Low-Enriched Uranium

185.7 keV

185.7 keV

background

Gamma Energy Gamma Energy

185.7 keV

[235U]

766.4 keV

[238U]

1001.0 keV

[238U]

backgnd

region

Uranium -Ray Spectra (NaI)


Mini MCA with CdZnTe Detector

MMCC

Material: Uranium

Technique: Gamma-ray

spectrometry

Purpose: Attribute test, 235U

enrichment

Detector: CdZnTe

(Options: NaI, Ge, He-3)


235U Spectra with a CdZnTe Detector

U fuels with various 235U enrichment


InSpector MCA with Ge Detector

IMCG

Material: Uranium,

Plutonium Technique: High resolution


Purpose: 235U enrichment,

Uranium (MGAU) Isotopics

Detector: Ge,


235U Spectra with Ge Detector

MGAU


Hand Held Monitor (HM-5)

Material: Uranium, Plutonium,

Other Nuclear Material

Usage: Isotope Identifier, Source Finder, Dose Meter, Active Length Measurements, Attribute test of U or Pu, U-235 Enrichment Measurements

Detector: NaI: 1”diam x 1”


R M L

I

Hand Held Monitor (HM-5)

NaI Detector

Display

Power/Function selection buttons

Power indictor LEDs Battery cover

Battery pack lock

Detector cover

Power/USB socket

Photomultiplier tube


Neutron Methods for Measuring

Uranium

• We’ve discussed gamma enrichment

measurements, which give us 235U

percentage

• We generally want total 235U mass

• We need neutron measurements to get the 235U mass


Neutron Methods for Measuring Uranium

Active counting system

Principle:

1) Fission is induced in uranium by

neutrons from AmLi source.

2) Multiple fission neutrons are detected

through coincidence counting.


Uranium Neutron Coincidence Collar (UNCL)

Material: Uranium

(LWR fuel assemblies)

Technique: Active neutron

coincidence counting

Purpose: Measurement of 235U

linear density in LWR fuel

assemblies

Detector: 3He tubes in

polyethylene Coincidence

Electronics


Active Well Coincidence Counter

(AWCC)

Material: Uranium

(cans, rods)

Technique: Active neutron


Purpose: 235U mass

determination in bulk UO2

powder, HEU metal, Research

Reactor Fresh Fuel Assemblies



Electronics


Pu Measurement

• High Resolution Spectrometry (Using a Ge

detector)

( Isotopic composition - 240Pueff fraction )

• Passive Neutron Coincidence Counting (HLNC,

INVS)

( 240Pueff mass )

Pu mass = (240Pueff mass) / ( 240Pueff fraction )


Plutonium Spectrum

0 100 200 300 400

93% 239

Pu

Co

un

ts (

Lo

g S

ca

le)

Energy (keV)

HPGe

CdZnTe

CdTe

NaI


InSpector MCA with Ge Detector IMCG

Material: Uranium,

Plutonium Technique: High resolution


Purpose: Plutonium

Isotopics

MGA Code analyses ratios

of gamma-ray intensities to

determine relative

concentrations of different

isotopes of Pu (238, 239,

240, 241, 242) and Am-241

Detector: Ge


Passive Counting System (no source)

Principle:

1) Detection of multiple spontaneous fission

neutrons from the Pu.

2) Combined with Pu Isotopics to determine total

Pu mass

Neutron Methods

for Measuring Plutonium


High Level Neutron Coincidence Counter (HLNC)

Material: Plutonium

Technique: Passive neutron


Usage: 240Pueff mass

Detector: 3He tubes


Electronics


Inventory Sample Counter (INVS)

Material: Plutonium

Technique: Passive neutron

coincidence

counting

Usage: 240Pueff mass (small

samples)



Electronics


Spent Fuel Measurements

Techniques and Instruments

• Cerenkov Glow: ICVD, DCVD

• Gamma-ray techniques: SFAT, IRAT

• Gross Neutron and Gamma-ray: FDET


Cerenkov Viewing Device (ICVD)

Material: Spent Fuel

Technique: Observe

Cerenkov glow from

irradiated fuel

Purpose: Attribute

verification of spent LWR

assemblies

Detector: Ultraviolet

radiation detection sensitive

device


CVD Images of BWR fuel, showing field of view of

Mark IVe ICVD with 105 mm and 250 mm lens


Digital Cerenkov Viewing Device (DCVD)

Camera Computer

Removable Flash Card

Displays

Heads-up

Display

LC Disp lay

Controller

UV Pass Filter

CCD/Peltier CoolerLens

DCVD system

comes with a

computer controller

and both a heads-

up and liquid-crystal

display.


DCVD Digital Cerenkov Viewing Device Layout


Spent-Fuel Attribute Tester (SFAT)


Assembly

Technique: Medium resolution

gamma measurement

Purpose: Attribute verification of spent

LWR assemblies

Detector and MCA: CdZnTe

Multichannel Analyser (MMCA)


SFAT Spent Fuel Attribute Tester


Spent Fuel Verification

Over assembly: Cs-137 and Co-60

Over gap: Background, no gamma peaks

20 40 60 80 100 120

1000

2000

3000

4000

5000

WWER-1000

CdTe Detector 90 mm3

Above gap

Above assembly

1172 and 1332 keV

Co-60

662 keV

Cs-137

Counts

/channel

Channels


FDET Fork Detector for Spent Fuel


Fork Detector Installation

Technique: Simultaneous neutron

and gamma measurements


Purpose: Attribute verification

of spent LWR assemblies


NDA Summary

• NDA is available and remains essential for verification activities for making independent checks

• Broad range of modern NDA instruments and techniques used for verification of nuclear material

• Selection of correct NDA equipment depends on goal of specific inspection / facility and capabilities of the NDA technique

Documents

Session 14 NDA technique used at a Typical NPP