PNNL-SA-98831

Dr. Theodore (Ted) W. Bowyer Laboratory Fellow

Pacific Northwest National Laboratory

Chair: CTBT Radionuclide Experts Group

Xenon Monitoring and the Comprehensive Nuclear-Test-Ban

Treaty

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The views expressed in this presentation do not necessarily reflect those of the Pacific Northwest National Laboratory, the US Department of

Energy, or the United States Government.

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How do you monitor (verify) a CTBT?

It is a difficult challenge to monitor the entire world for nuclear tests, regardless of size

Underground Above ground Underwater

kiloton or more), nuclear tests: Shake the ground Emit large amounts of radioactivity Make loud noises if in the atmosphere (or hydroacoustic waves if underwater)

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International Monitoring System Technologies Seismic sensors

Detecting earth movement Must separate explosions and 100+ earthquakes per day Can pinpoint the location of the event to with 1,000 km2 or better

Infrasound

Low frequency sound waves Affected by wind noise Most useful for atmospheric detonations

Hydroacoustic Underwater blasts

Expensive sensors, but only a few are needed to monitor all of the oceans (and whales) because these pressure/sound waves travel far in water

Radionuclide detection Atmospheric detonations

Huge amount of radioactivity released

Underground detonations Radioactive xenon may be released

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Topics of interest to Nuclear Professionals

Early 1990s Goal: Incredibly sensitive detection of airborne radionuclides in the atmosphere indicative of a nuclear explosion

Equipment ~106 times more sensitive than ordinary sensors 2013 status: Network ~80% completed at sensitivities needed

Issues

Specialized techniques (no commercial off the shelf technology exists) to

processes Customized technology Custom software

Negotiation of on-site inspection techniques that are effective for the detection of nuclear tests, yet do not reveal other unrelated sensitive information to inspectors

For example, national security sensitive information at a former nuclear test site

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Radionuclide Detection in the IMS

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The International Monitoring System The International Monitoring System was

established with 321 stations and consists of Seismic, Airborne radionuclide, Hydroacoustic, Infrasound

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Radionuclide Detection Fission and activation products from a nuclear explosion can be liberated into the atmosphere and detected remotely

4 1018 m3 air

133Xe produced from a 1-kiloton nuclear detonation (after 3 days) ~1016 Bq

= 10 mBq/m3

Easy to

Concentration ~ 0

Station

High Concentration Concentration ~ 0

A dense RN network is needed

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Radionuclide Stations

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PNNL-SA-98831 What Makes a Good Analyte for the Detection of Nuclear Explosions? Should be as definitive as possible

-to- No problems with interpretation

Should be possible to measure using ordinary means

Interpretation we must design idiot- (PhD-) proof technology

Must be robust and have diagnostics Systems or processes used to detect it should adhere to some fiscal reality

1993 Target was $100k per system; $1M is the current estimated cost

Radioactive xenon is the best candidate Is produced in large quantities and is the most likely to be emitted from underground Has reasonable backgrounds most places Has reasonable half-lives

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RN Stations in the International Monitoring System

Airborne radioactive debris can be in the form of radioactive particles or radioactive gases Each completely automatic IMS radionuclide station consists of either

A particulate monitoring system or

A particulate monitoring system and radioactive noble gas (xenon) system

Each IMS radionuclide station may also send the physical debris to one of 16 designated laboratories for confirmatory analysis

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PNNL-SA-98831 General Capability of IMS Radionuclide Systems

Particulates Completely automatic systems available commercially Data sent to the International Data Center Sensitive to gamma emitters only Detection sensitivities in the 1-10 µBq/m3 range Planned 80 stations (>80% complete) 24-hour collection, 24-hr of decay for Rn, then count starts Samples archived onto filter paper Some samples can be sent to a series of labs for reanalysis Measurements are quality controlled and the equipment undergoes a certification process

Noble gases (131mXe, 133Xe, 133mXe, 135Xe) Completely automatic systems available commercially Data sent to the International Data Center Sensitive only to radioactive xenon Detection sensitivities in the 0.1-1 mBq/m3 range Planned 40 stations (~75% complete) with 40 more possible 12-hr collection, followed by 24-hr count Samples archived into bottles for a short period Some samples can be sent to a series of labs for reanalysis Measurements are quality controlled and the equipment undergoes a certification process

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RN Technology General Specifications

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The

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Radionuclide Technology Pictures

PNNL-SA-98831 Particulates (i.e., dust and dirt with non-gaseous radionuclides)

Huge amounts of activity are released in atmospheric detonations

An Aside - Radioactive aerosols (particulates)

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RASA Aerosol Details

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Six Strip Segmented Sample Head

Lead Shield

Polyester Rolls

Drive Rollers

Filte

r Sup

ply

High Purity Germanium Detector

Aerosol collection and measurement

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RASA Filter Paper

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3M SBMF-40VF NaCl Test

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

0 0.1 0.2 0.3

Microns

Trap

ping

Effi

cien

cy

1x120

2x120

3x120

Aerosol Filter

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Radioactive Xenon Detection Systems

Radioactive xenon isotopes 131mXe, 133Xe, 133mXe, 135Xe

Large amounts produced and (likely) released from nuclear explosions Are definitive with the use of isotopic ratios

Still a complex measurement for non-specialists, though high quality, reproducible measurements can be made routinely using specialized equipment Fiscal realities

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Schematic of Xenon System

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Typical xenon monitoring system for the IMS A small chemical engineering plant with a dedicated, specialized nuclear detector

Radioactive Xenon Separation and Detection

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Radioxenon Analysis Uses Correlated Beta and Gamma Measurements

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0 100 200 300 400 500 600 7000

100

200

300

400

500

600

700

Beta Energy (keV)

Gam

ma

Ener

gy (k

eV)

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Totally unfair (but illuminating) example * If all of the activity vented from a 1 kiloton nuclear

atmosphere (1018 m3) it would yield a concentration in the atmosphere of: 5x1017 Bq / 1018 m3 = 0.5 Bq/m3

-> The detection limits of the radionuclide samplers are in the range of 1x10-5 Bq/m3

Amount of Release of Radionuclides The amount of radionuclides released can vary from <10-7 of the test to 100% of those produced

The total amount of activity produced is about 5x1017 Bq (disintegrations per second) per kiloton at t=1 day

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How Large is our Signal?

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The production of 99Mo medical isotopes needed for medical procedures around the world also produces and emits huge amounts (though at very low dose levels) of radioactive Xe Several production locations around the world

Emissions can be tracked across the world Scientific studies are underway to understand the isotopes emissions and ways to avoid or account for them

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(Un)Expected sources of background

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Medical Isotope Production Effects*

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*Based on published data and assumptions about release frequency.

Daily Release (Bq) Facility 1.440E+13 Chalk River, Canada 1.600E+12 MDS Nordion, Kanata, Canada 2.500E+09 Mallinckrodt, Petten, Netherlands 4.600E+12 IRE, Fleurus, Belgium 1.300E+13 NECSA, Pelindaba, South Africa 1.665E+12 CNEA, Buenos Aires, Argentina 1.850E+12 ANSTO, Lucas Heights, Australia 7.800E+12 Batan Serpong, Indonesia 6.240E+12 RIAR, Dimitrovgrad, Russia 1.560E+12 Karpov Institute, Obninsk, Russia

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Simulated background from Isotope Production in South Korea

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102

100

10-2

10-4

10-6

100 105

Xe-

135/

Xe-

133

X e-133m/Xe-131m

Reactor Operations

Possible Nuclear Explosion

Medical Isotope Production

Discrimination Between Types of Events

If the plume travels over a station, discrimination between event types is possible under some circumstances If 3 or 4 of the isotopes are detected above the detection levels

concentrations lower than possible to detect

Event falls clearly in one part of phase space or the other

happen because of error bars and medical isotope production

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The production of medical isotopes is similar to a nuclear explosion; unlike reactors

Irradiation of uranium, followed by dissolution as soon as possible A constant presence of radioxenon causes a background that can be

therefore the statistical precision to which we can subtract it is affected This effect persists even if the amount at the location can be calculated from stack monitoring data

133m

133 131m

135

Xenon Fog

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On-Site Inspection

Detection of radionuclides in the environment near a presumed ground zero

Isotopes targeted: 37Ar, 95Zr, 95Nb, 99Mo, 99mTc, 103Ru, 106Rh, 132Te, 131I, 132I, 131mXe, 133Xe, 133mXe and others

Techniques to detect radionuclides vary widely

Debris may be expected Above, at, or below the surface Gaseous or particulate forms At low or high levels

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Radionuclide Detection for OSI

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Xenon (and Argon) and On-Site Inspection

Radioxenon and radioargon are often considered one of the smoking guns for an on-site inspection Local (on-site) concentrations of radioactive xenon and argon noble gases are expected to be x1000s or more above remote levels, for months after the detonation

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Concentrations Expected

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Important Examples

DPRK-1 Detection of Xe-133 in IMS station in Yellowknife, Canada as well as report of detection of Xe-133m and Xe-133 in the ROK at low levels

DPRK-2 No detections reported

DPRK-3 Detection of Xe-131m and Xe-133 at appropriate ratios, easily observed in two IMS stations, at ~55 days following the seismic event

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Side Example - Fukushima Reactor Accident

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Detected across the IMS at >105 -106

detection level

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Summary - Challenges for the NG Community

Understanding background Atmosphere (IMS): Medical isotope production and nuclear reactors cause a xenon weather in the atmosphere Subsurface (OSI): Complex geologies, atmospheric pumping, and variable crustal elements can cause variable xenon isotopes in the background from spontaneous fission

Density The IMS needs more xenon measurement systems to maximize probability that a plume travels across a station

Data quality The current data quality of NG stations needs to be improved and cross checked it is still a relatively new technology

Data interpretation Understand all the signals, all the time when there are complex backgrounds and venting mechanisms

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