part e. radiation monitors

1 / 29Radiation Safety - JUAS 2014, X. Queralt

Part E. Radiation monitors

Part E. Radiation monitors


0

50

100

150

200

250

0 1 0 2 0 3 0 4 0 5 0

mA

0.1

1.0

10.0

0 10 20 30 40 50

days since 18/01/02

do

se

ra

te (

S

v.h-1

)

Example: photon dose rate measurement around ESRF storage ring

Radiation monitors


I

w H2 He O2 Ar Air

electrons 36.3 eV 41 eV 31 eV 26.4 eV 34 eV

alphas 36.5 eV 44 eV 32.4 eV 26.4 eV 35.3 eV

VI

V

ionisation chamber

proportional counter

Geiger-Müller counter

IVe

w

dt

dD

dt

dN

V

w

dt

dD

w

EN

gasgas

pairs

gasgas

pairs

EE

Gas-filled detectors

Radiation monitors


Ionization chambers

Radiation monitors


Proportional counter

Radiation monitors


Geiger - Müller counter

Radiation monitors


Neutron monitors

Example: neutron spectrum around the 1.7 GeV BESSY storage ring (Courtesy of Klaus Ott)

Radiation monitors


%)6(MeV792.2Li

%)94(MeV310.2LiBn

keV765HpHen

73

7310

5

33

3He-filled proportional counter:

BF3 counter:

Polyethylene moderator

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

energy (eV)

cros

s se

ctio

n (b

arn)

3He(n,p)3H33He(n,p)He(n,p)33HH

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E+05

1.E+06

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

energy (eV)

cros

s se

ctio

n (b

arn)

3He(n,p)3H33He(n,p)He(n,p)33HH

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

energy (eV)

cros

s se

ctio

n (b

arn)

10B(n,)7Li1010B(n,B(n,))77LiLi

1.E-02

1.E-01

1.E+00

1.E+01

1.E+02

1.E+03

1.E+04

1.E-02 1.E-01 1.E+00 1.E+01 1.E+02 1.E+03 1.E+04 1.E+05 1.E+06 1.E+07 1.E+08

energy (eV)

cros

s se

ctio

n (b

arn)

10B(n,)7Li1010B(n,B(n,))77LiLi

Moderated neutron monitors

Radiation monitors


0

0 .2

0 .4

0 .6

0 .8

1

1 .2

1 .E-4 1 .E-3 1 .E-2 1 .E-1 1 .E+0 1 .E+1 1 .E+2

e n e rg y (Me V)

µS

v .

cm

2 (

rela

tiv

e u

nit

s)

ICRP

CRAMAL-31


Radiation monitors



Neutron response enhancement using lead-shell in moderator type counters

BertholdLB-6411

Radiation monitors


expanded bubble(~ 0.1 – 0.6 mm)

superheated drop(20 – 100 m)

neutron

chargedparticle

vapour embryo< 0.1 m

Superheated emulsions

0

8

0 3

temperature

pre

ssu

re

solid

liquid

vapour

superheating

over-expansion

Radiation monitors


Thermal neutrons: OK

Epithermal neutrons: not important

0.1 – 10 MeV: OK

Under-read > 10 MeV

Energy response of SDD100 vials (dichlorodifluoromethane)


Radiation monitors



effect of lead moderator

Radiation monitors


Acoustic bubble counting

Model ABC1260Framework Scientificwww.framesci.com


Radiation monitors


Spectrometer

Gamma (X-ray)

Gamma (X-ray)

Gamma (X-ray)

Neutrons

Radiation monitors


COMPANY MODEL ENERGY RANGE DETECTION RANGE

THERMO SmartION Mini 2100S >10keV 0-500mSv/h

FLUKE Victoreen 451P >25keV <50mSv/h

THERMO FH40 G-L10 >30keV 10nSv/h - 100mSv/h

THERMO FHZ 672 E-10: 48 keV - 4.4 MeV 1nSv/h - 100mSv/h

THERMO RadEye PRD 30 keV – 1.3 MeV 0.01 μSv/h – 250 μSv/h

THERMO FHT 752 SH 0.01 - 100,000 cps

THERMO RadEye N >0.005 cps

Radiation monitors


FHT192 FHT 762 Wendi-2 EPD0 Manufacturer Thermo Electron GmbH Thermo Electron GmbH Thermo Electron GmbH

1 Particle Photons Neutrons Photons

2 Energy range 30 keV– 7 MeV 25 meV–5 GeV 15 keV–10 MeV

3 Measuring range 100 nSv/h–1 Sv/h 1 nSv/h – 100 mSv/h Resol. 1 mSv/h:<0.5 Sv/h – 4 Sv/h Resol. 1 Sv/h:4–50 Sv/h

4 Energy response Calibration factor resp. Cs-137:For low dose rate:0.01-0.02 (μSv/h)/cpsFor high dose rate:1.9 - 2.2 (μSv/h)/cps

Calibration Factor:

1.14 (μSv/h)/cps

Ref. Cs-137 ±30% from 17keV to 6MeV ±50% from 6MeV to 15Mev

5 Quantity Hp(10) Hp(10) Hp(10)

8 Type Active Ionization chamber Active Proportional counter Active semiconductor dosimeter

9 Sensitive material Inert gas (7 bar) He-3 (2 bar) + polyethylene moderator

Silicon diode detectors

10 Dead Time Dead Time for high dose rate: 6-7 μs

Dead Time: 1.8 μs --

• Active radiation detectors:

Radiation monitors


TR01GN: Tunnel Detector – Septum Magnet & Kickers

Radiation monitors


TR07N TR09N

TR07N

EH33GNTR06G

TR03GN

• Radiation Monitors Network reinforced by movables monitors

Experimental Hall

1. Engineering solution


D2 Gamma DR (uSv/h)

0

0.2

0.4

0.6

0.8

1

1.2

1.4

September 16th ’09

From 2nC to 4nc

Close a bit scraperOpen scraper

Start bending magnet scan

PSS trip due to dose rate alarm



Gamma dose rate due to the Cu scrapper scans

26-Sep-2008SCRAPER SCANSCharge/pulse: 4nC/pulsoEnergy: 109MeVFrequency: 1Hz

1.4 µSv/h

RMN: Cu SCRAPPER DATA



Scraper scans

One klystron trip

D2D1T1

RMN: LOCAL SHIELDING EFFECT



Max. charge: 4nC/pulseMax. energy: 109MeVFrequency: 1Hz

Total accumulated dose (maximum values):



Integrated dose measured at the shield wall next to: BL16 & BL18 & BL20

51.7 µSv

26.5 µSv

9.8 µSv

12th March ‘11

Stored beam: 0.2 mA

EH16G

EH18G

ZONA CONTROLADA

RIESGO DE IRRADIACIÓN EXTERNA

ZONA CONTROLADA


ZONA VIGILADA


ZONA VIGILADA


Integrated over 4 hours period



RADMON next to (integrated dose):

BL16 & TR03 (next to BL16) & BL27 & TR01 (next to BL27)

2.5 µSv

1st: 100 mA30th: 50 mA

Stored beam: 100 mA

EH33GN

EH16GEH27G

TR03GN



RADMON next to (gamma dose rate):

BL16 & TR03 (next to BL16) & BL27 TR01 (next to BL27)

50 µSv/h

5 µSv/h

20:25 22:0014:00

EH16G

EH27G

TR03GN



References

Radiation Safety – JUAS 2007, P. Berkvens

NCRP Report No 51: Radiation Protection Design Guidelines for 0.1-100 MeV Particle Accelerator Facilities. NCRP, 1979 - Although dated, still very useful. Scope limited to mostly radiation source terms and shielding. Concise, only technical information.

NCRP Report No 144: Radiation Protection for Particle Accelerator Facilities. NCRP, 2003.

It is a substantial revision and expansion of NCRP Report No. 51, the Report revises and expands on the earlier report and includes new information on source intensities, shielding, dosimetry, and the environmental aspects of particle accelerator operation. It is primarily concerned with radiological safety aspects that are special to the operation of particle accelerators having energies above about 5 MeV up to the highest energies available, while not neglecting low-energy neutron generators.

IAEA Report No. 188: Radiological Safety Aspects of the Operation of Electron Accelerators, IAEA, Vienna,1979. - Scope limited to electron machines. Very detailed and comprehensive: all facets covered, except safety systems. Strongest points: source terms, shielding, yields (activation, ozone, noxious gases). Although dated, still a “must” for electron machines.

IAEA Report No. 283: Radiological Safety Aspects of the Operation of Proton Accelerators, IAEA, Vienna,1988. - Equivalent to No. 188 for proton machines. More detailed, good reading on general issues, with some high-energy bias.


ReferencesSLAC Report 327: Health Physics Manual of Good Practices for Accelerator Facilities. Stanford Linear Accelerator Center, - Written by a committee from DOE accelerator labs - bias towards large, high-energy facilities. Little technical detail, but strong on operational issues, including safety systems. Certain aspects not found elsewhere; useful general reading.

Landolt-Borstein Compendium: Shielding Against High Energy Radiation, 1990, Springer- Verlag - Written by former members of the CERN Radiation Protection group (Fasso et al). Very expensive, availability limited. Encyclopedic approach - compilation of large amounts of available data. Not good for general reading and learning, but a valuable reference for specialists.

A. H. Sullivan: A Guide to Radiation and Radioactivity Levels near High Energy Particle Accelerators, 1992, Nucl. Technology Publishing - Small “cookbook” with limited scope, but very practical. Essence distilled to rules-of-thumb and simple formulae.

ICRP Publication No 60: 1990 Recommendations of the International Commission on Radiological Protection, Oxford, 1991, Pergamon Press – Contains the latest recommendations on quantities and units for radiation protections, in particular the concepts of equivalent dose and effective dose.

ICRP Publication No 103: 2007 The 2007 Recommendations of the International Commission on Radiological Protection – It is an update of the No 60 and also include an approach for developing a framework to demonstrate radiological protection of the environment.


Many Thanks for your attention!

part e. radiation monitors

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