Nuclear materials analysis using an array of - PowerPoint Presentation

Slide1

Nuclear materials analysis using an array of g-ray transition-edge sensors and microwave SQUID readout

Joel UllomNIST and the University of Colorado

with support from DOE NEUP and DOE NE

1

Contributors

B. K. Alpert,

D. T. Becker

, D. A. Bennett, J. W. Fowler, J. D. Gard, G. C. Hilton, J. A. B. Mates, N. Ortiz, C. D.

Reintsema

, D. R. Schmidt, D. S.

Swetz

, L. R. Vale, A. L. Wessels, A. S. Hoover,

K. E. Koehler

, S.

Kossmann, M. W. Rabin, M. Yoho, M. P. Croce

2

Motivation

nuclear power provides 11% of world’s electricity

nuclear power both consumes and produces isotopes of U and Pu that must be monitored and safeguarded

Rokkasho

(Japan)

Savannah River H-Canyon (USA)

capacity of

Rokkasho

= 800,000 kg/year spent fuel containing 8000 kg of Pu

safeguards target: account for all Pu to < 8 kg per year = 0.1% (!)

mass spectrometry (MS) achieves this accuracy but requires sample handling and is time intensive. 6,000 MS analyses per year for H-Canyon.can g-ray spectroscopy with LTDs compete with MS?3

LTDs and nuclear materials analysis

NIST and Los Alamos have worked together since 2004

performance of LTDs must be compared with HPGe

TESs

HPGe

from BSI scientific instruments

HPGe

LTDs provide 50 eV FWHM resolution at 100 keV vs 400 eV. But,

HPGe

provides areas > 5 cm

2

and count rates > 10 kHz

Useful spectra contain ≳ 5x10

7

counts so LTD arrays required

4

36 TES sensors with bulk Sn absorbers (4 spares)

33 channel SQUID amplifier (1 spare)

S

pectrometer to

L

everage

E

xtensive

D

evelopment of

G

amma-ray TESs for H

uge

A

rrays using

M

icrowave

M

ultiplexed

E

nabled

R

eadout

(

SLEDGEHAMMER

)

SLEDGEHAMMER

g

-ray TES instrument

detector package with 256 TESs and microwave SQUID readout

SLEDGEHAMMER

g-ray TES instrument (2)

ROACH2 SDR electronics and

m

mux

firmware

Gard, JLTP, 2018

spectrometer at LANL and users

stable operation at ~400 cps/sensor

(but acquire spectra at lower rates)

<ΔE> = 55 eV at 97 keV

6

Application #1: enrichment of HALEU fuel

HALEU = High Assay Low Enriched Uranium

235U/238U = 5 - 19.75% , preferred for emerging reactor conceptsWant to know 235

U/

238

U ratio in fresh fuel.

235

U has line at 186 keV. 238U harder …

7

Application #1: enrichment of HALEU fuel

HALEU = High Assay Low Enriched Uranium

235U/238U = 5 - 19.75% , preferred for emerging reactor conceptsWant to know 235

U/

238

U ratio in fresh fuel.

235

U has line at 186 keV. 238U harder …

113.5 keV line from direct decay of

238U is observed by TES, suggests potential to measure enrichment

Planar HPGeTES1 kg U3O810% 235

U

238

U

113.5 keV

8

Application #2: actinide

isotopics

Isotopic mix (

238

Pu -

242

Pu,

241Am, and others) tells processing history, neutron history, and likely purpose of material. Useful for plant operations and safeguards.

Traditional to determine isotopic ratios, e.g.

2XX

Pu/239Pu Use of HPGe g-ray spectroscopy heavily studied since 1970s. Existing software tools = FRAM, MGA, … . Accuracy limit on ratios = ~ 1%. Can TESs do better?Building on earlier work with first TES calorimeter array instrument: Bennett, RSI, 2012; Hoover, IEEE TNS, 2013; Hoover, IEEE TNS, 2014

reactor types

higher burnup

from

Wallenius

, 2001

9

Analyze CBNM-Pu61 mixed actinide sample

4 cm

region of interest (ROI)

calibration feature

10

Analyze CBNM-Pu61 mixed actinide sample

241

Am (98.95 keV)

238

Pu

(99.85 keV)

239

Pu (98.78 keV)

U x-ray (98.43 keV)

Sn escape

Sn escape

Pu x-ray

(98.78 keV)

some peaks used for analysis

some nuisance peaks

fit data for peak areas

what about efficiency?

h

(E)

depends on detector

and

source construction

99 keV ROI

4 cm

region of interest (ROI)

calibration feature

11

Isotopic analysis explained

CombinedSpectrumBreak into ROIs

12 ROIs

Fit each ROI

15 Peak Areas

(98.95 keV to 208 keV)

Fit for Efficiency Curve & Intensity Ratios

Branching Ratios

Half-Lives

PuO

2, Cd Mass Attenuation Coefficients

Efficiency Model

Intensity Ratios

Efficiency Parameters

Isotopic Mass Ratios

12

A

j

= Sum[

I

k

BR

jk

h

(

E

j

)

]

A

j

= area of peak with energy

E

j

I

k

= decay intensity of isotope k

BR

jk

= branching ratio for isotope k to energy

E

j

h

(

E

j

)

= source-detector efficiency at energy

E

j

solve for 9 free parameters using 15 equations:

MEASURED

FIT (5)

TABULATED

FIT (4)

13

reduced chi^2 = 1.01

(arb.)

CBNM Isotope Analysis

efficiency curve

h

(E) = model + 4 free parameters

Pu absorption edge

h

(E)

=

14

reduced chi^2 = 1.01

(arb.)

CBNM Isotope Analysis

efficiency curve

h

(E) = model + 4 free parameters

Pu absorption edge

Isotope

Declared Mass Ratio to Pu239

Measured Mass Ratio to Pu239

DifferenceStatistical Uncertainty

Total Uncertainty

Pu238

0.01484

0.01482

-0.15 %

0.22 %

0.98 %

Pu239

1.00000

1.00000

N/A

N/A

N/A

Pu240

0.40532

0.39998

-1.32 %

0.26 %

1.14 %

Pu241

0.02243

0.02241

-0.08 %

0.23 %

0.89 %

Am241

0.10377

0.104020.23 %0.21 %1.26 %

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Isotope

Declared Mass Ratio to Pu239

Measured Mass Ratio to Pu239

Difference

Statistical Uncertainty

Total Uncertainty

Pu238

0.01484

0.01482

-0.15 %0.22 %0.98 %Pu2391.000001.00000N/AN/AN/APu2400.405320.39998-1.32 %0.26 %1.14 %Pu2410.022430.02241-0.08 %0.23 %0.89 %Am2410.103770.104020.23 %0.21 %1.26 %

this accuracy is excellent!

CBNM Isotope Analysis

reduced chi^2 = 1.01

(arb.)

efficiency curve

h

(E) = model + 4 free parameters

Pu absorption edge

this accuracy is excellent!

CBNM Isotope Analysis16

Isotope

SLEDGE Difference

HPGe

Difference

Pu238/Pu239

-0.15 %

0.695%

Pu239

N/A

N/APu240/Pu239-1.32 %4.53%Pu241/Pu239-0.08 %-1.95%Am241/Pu2390.23 %5.61%SLEDGEHAMMER results significantly more accurate than HPGe Difference between declared isotopic ratios and measured values from SLEDGEHAMMER and a LANL HPGe analysis

Next: Spectrometer Optimized for Facility Integrated Applications (SOFIA)

air-cooled, single phase, 3 kW compressor

256 TESs and microwave readout; > 5000 cps

fully-automated data processing software

compact cryostat with reduced utility needs

New algorithms for combining individual pixel data, drift correction, and energy calibration are now implemented in a one-button software tool

Energy calibration is determined from patterns of peaks that result from the instrument response

see

poster #90 by

M.

Croce and #58 by K. Koehler

spectrometer can operate at more sites, can access more nuclear materials

17

18

SLEDGEHAMMER

Mates, APL,

2017

SOFIA

500 pixel

g

-ray spectrometer for Idaho National Laboratory (2020)

1,000 TES soft x-ray spectrometer for SLAC LCLSII

Hyperspectral X-ray Imager (HXI) at LANL

nuclear materials analysis

hard x-ray spectroscopy

SLEDGEHAMMER family tree

soft x-ray spectroscopy

hard x-ray spectrometer

with

the Advanced Photon Source

3,000 TES spectrometer at NIST for x-ray tomography

HOLMES TES array for

163

Ho electron capture

electron capture

and more instruments will follow …

19

Summary

Nuclear materials analysis is important and has played an important role motivating the development of microcalorimeter instruments

SLEDGEHAMMER is the first microcalorimeter instrument with microwave SQUID readout. The channel count, dynamic range, and stability of the readout are highly enabling.

SLEDGEHAMMER can provide better analyses than

HPGe

although more samples must be measured

Isotopic results are likely limited by uncertainties in tabulated branching ratios. Will soon use spectral data + mass spectrometry composition information

to fit for the branching ratios.

Subtle effects from

assumed form of efficiency curve also merit further studyThe SOFIA instrument will soon enable measurements of a wider range of nuclear materials because of its ease-of-useA larger instrument is under development for Idaho National Laboratory’s analytical laboratory

20

Thanks!

We are looking for post-docs for several projects. Please contact

joel.ullom@nist.gov

Isotope Ratio

CBNM-Pu61

CRM-136

PIDIE6-1

PIDIE6-6

Pu

238/Pu239

0.22

N/A

0.311.88Pu240/Pu239

0.29N/A0.300.14Pu241/Pu2390.04N/A0.770.23Am241/Pu2390.04N/A0.220.39Ratio of uCal error to HPGe error

Analysis results from 4 sources

uCal

better (< 1)

HPGe

better (> 1)

**PRELIMINARY**

Spectral ROIs Used for Isotopics

22

values < 1%,

necessary and promising