Safety aspects in Particle
Accelerator
Pramod V Bhagwat
Head, Ion Accelerator Development Division
BARC
23-11-2016
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Outline
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Type of Accelerators
Accelerators in BARC
Radiological Safety aspects
Safety aspects of Non-ionizing radiation
Safety framework in BARC
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• Broadly particle accelerators are classified to the following
categories..
– Electrostatic or DC Accelerator
– RF Accelerator
– Synchrotron or storage rings
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Accelerators in BARC
I.
II.
III.
IV.
V.
VI.
VII.
VIII.
IX.
X.
XI.
XII.
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Pelletron-Linac facility, NPD at TIFR
Medical cyclotron, RMC, Parel
6 MV Folded Tandem Accelerator (FOTIA), IADD
Tandetron at NCCCM, Hyderabad
14 MeV Neutron Generator, NXPD
7 MeV Linac, Radiation & Photochemistry Division
ILU-EBA (5 MeV, 15 kW)
500 KeV, Electron accelerator, APPD, BRIT, Vashi
3 MeV electron Linac, Electron Beam Centre, Kharghar
10 MeV electron Linac, Electron Beam Centre, Kharghar
Electron Cyclotron Resonance Ion source at 100 kV, NPD
20 Mev Proton Accelerator, IADD
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First high voltage generator
Sir John Douglas Cockcroft was a British
Physicist. He shared the Noble Prize in
Physics for splitting the atomic nucleus with
Ernest Walton.
Ernest Thomos Sinton Walton was an Irish
Physicist and Noble Lauraete for his work
with John Cockfrcroft with “atom-smashing”
experiments done at Cambridge University in
the early 1930s.
(27 May 1897-18 September 1967)
7Li
+p
4He
+4 He and 7Li + p
7Be
+ n.
at 400 keV, first nuclear reactions; Nobel prize 1951.
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( 6 October 1903- 25 June 1995)
Cascade Generator
The
charge
particle
accelerators
are
being
increasingly
used,
both
directly and indirectly, for
research in many frontier
areas of science. They are also
indispensable
for
varied
applications ranging from
materials science to medicine
and, more recently, even for
radioactive-waste
transmutation and energy
production. In early sixties a 1
MV Cascade generator was
installed at TIFR .
Dr H J Bhabha in front of Cascade Generator
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Van de Graaff Generator
(December 20, 1901- January 16, 1967)
•
•
•
•
The belt is electrically charged by a brush
or comb.
The charge can be negative or positive
depending on the polarity of the source
The resulting terminal voltage is a
function of the diameter of the terminal
electrode
In order to achieve higher voltages the
Van de Graaff accelerator is enclosed in a
high pressure vessel (SF6 or mixture of N2
(80%) and CO2 (20%).
Disadvantages:
•These belts suffered from a number of operational difficulties including termin
instability and susceptibility to spark damage.
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•Generated belt dust necessitating frequent
cleaning inside the accelerator tank.
Pelletron –Linac Facility
•
•
•
•
•
•
Model 14 UD from NEC, USA
Column voltage rating
15 MV
Tube voltage rating
14 MV
Voltage stability
± 2 kV
Proton energy range
8 to 28 MeV
Heavy ion energy range 4(n+1) to
14(n+1)MeV
• Test current values
Protons
3-5 µamps.
Alphas
2 µamps.
Heavy ions
100 ηA
particle
Specifications of Pelletron
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Raymond George Herb
22-01-1908 – 01-10-1996
Folded Tandem Accelerator
Specifications
Column voltage rating 6MV
Voltage stability ± 2 kV Heavy ion
energy range:
1(n+1) to 5(n+1) MeV
Proton energy range
1 to 5 MeV
A schematic diagram of Folded Tandem Ion Accelerator
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Folded Tandem Accelerator
The 5.5 MV single ended Van-de-graaff
accelerator was converted into a 6 MV
folded heavy ion accelerator using NEC
accelerating tubes and column. The
negative ions are generated by a SNICS
source floating at -200 kV deck potential
and then bend by 900 using a
combination of electrostatic deflector
(200) and injector magnet (700). The ion
beam in the terminal is bend by a 1800
magnet after the stripper. The power to
the folding magnet and various
electronic devices in the terminal is given
by a 5 kVA alternator, operating at 400
Hz, specially designed for this purpose.
The alternator rotates at 1500 rpm and
driven by a segmented Perspex shaft.
The accelerator is operational since 2000
and routinely used for various
applications.
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Pelletron –Linac Facility
-ve ions
+ve ions
•
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Pelletron Accelerator
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Positive Ion Injector Schematic
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Available Energy Range
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PK-ISIS Set Up - I
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U beam spectrum
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Medical Cyclotron
The 16.5 MeV cyclotron was installed in 2002
at Radiation Medicine Centre, Parel and since
then it has been operational. This accelerator
has given exceptional service to the society
and a large number of patients have been
treated so far. Negative H ion is accelerated to
16.5 MeV and bombarded on enriched water
(H2O18). Thus, 18F is formed which has a halflife of 110 min. FDG is produced for in-house
use and supply to other hospitals. Over 60
patient doses prepared daily at < Rs. 5000 per
dose. [F-18]NaF, [F-18]FLT and [F-18]FMISO are
also produced routinely.
Medical cyclotron, RMC, Parel
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3 MV Tandetron Accelerator
The Tandetron accelerator (3 MV) was
installed and commissioned in 1995 with a
minimal self-sufficient configuration. The main
accelerator consists of a dual ion source
injection system with a 900 analysing magnet, a
3 MV high voltage terminal system with a
stability of ± 300 V, an analysing magnet at
high energy end with 5 port switching magnet
chamber supported by an electrical quadruple
triplet lens and other beam handling system.
The beauty of this accelerator is that after its
installation, the tank was opened only once for
servicing.
Typical applications of this
accelerator are depth profiling of light elements
( H, Li, B, Al, Mg) by nuclear reaction
analysis, compositional analysis and thickness
determination by RBS, elemental analysis of
bulk material by PIXE and PIGE etc.
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3 MV Tandetron Accelerator
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14 Mev Neutron Generator
This accelerator is a Cockroft-Walton type and
generates +300 kV. Radio Frequency (RF) ion source
can accelerate H+ or D+ ions. The accelerated ions at
300 KeV, when bombarded on a target which consists
of Deuterium/Tritium absorbed in Titanium on a 1 mm
thick and 30 mm dia. Copper disk, generates 14 MeV
Neutrons. The accelerator is being used for Neutron
radiography, Fissile material Detection, Prompt
capture gamma experiments. Using BGO detectors
nitrogen capture line at 10.86 MeV was identified in
Urea, Chlorine and other elements. Recently,
accelerator was coupled to an ADS experimental setup.
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14 Mev Neutron Generator
Experimental Thermal ADS - BRAHMMA
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7 Mev Linac
Research Activities
Radiolysis facility which is based on 7 MeV Linac
was procured from M/s Radiation Dynamics, UK
and commissioned in 1986. Since then it is
providing trouble-free service and main work horse
of RPCD. The electron energy spread is ± 0.4 MeV
and operates at 3000 MHz. The electron beam is
available at 25, 50, 100, 200, 500 and 2000 nsec
pulse width and corresponding peak current at
900, 400, 200, 150, 90 and 70 mA. In a
collaborative effort with Laser Electronic Support
Division, (LESD) of RRCAT, a new pulse slicer unit
has been developed to generate continuously
tunable pulses right from 1 microsecond down to
30 ns duration. The facility has wide applications
mainly radiation Chemistry in nuclear energy
systems, development of efficient antioxidant and
radio-protectors, Nanomaterials research and
investigation of radiation effect in biological
systems.
[1] Radiation Chemistry in nuclear energy systems
Current nuclear fuel cycle requires investigations of the
fundamental chemical processes resulting from intense radiation,
high temperatures and extremes of redox potential and high
acidity. These information are needed to understand:
 Coolant behaviour
 Gas generation in the core
 Corrosion behavior of the core materials
 Extractants for the targeted separation processes
 Storage materials for nuclear waste
 Chemical decontamination formulations
[2] Development of efficient antioxidant and radio-protectors
[3] Nanomaterials research
Synthesis of metallic and semiconductor nanomaterials
Tuning of surface properties, opto-electronic, magnetic
properties
Behaviour of device materials like semiconductor
nanomaterials, LCD etc at high radiation doses
[4] Investigation of radiation effect in biological systems
A technique which works in interdisciplinary areas of Radiation
and Photochemistry.
7 MEV LINAC, RADIATION & PHOTOCHEMISTRY DIVISION
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2 Mev Electron Linac
The 2 MeV electron beam accelerator has been successfully functioning since 2001 at
BARC-BRIT complex, Navi Mumbai. This facility comprises of an electron beam machine
which is a cavity resonator type, RF pulse accelerator with electron beam energy 2 MeV
and current 10 mA with a scanning width of 900 mm. A power roller conveyor system has
been installed to transport the material in & out of the irradiation cell area and a linear
conveyor for transporting the material to & fro so that desired dose can be delivered to the
product. Among the applications of this accelerator Polymer processing (crosslinking of PE
O-rings, cable insulations, heat shrinkable materials, tyre components etc), Diamond
colour enhancement and Waste water treatment (on pilot scale) are important one.
Recently this accelerator was upgraded to ILU-EBA (5MeV/15kW). Its application in low
dose (0.25 kGy to 1.0 kGy) includes disinfection of packed powders, cereals, grains, Fish,
Meat (in cold condition) etc, in medium dose (1.0kGy -30kGy) Medical products
Sterilization, Polymer material etc and on high dose Polymer crosslinking & degradationO-rings, HS components; thick polymer samples; Semi-Precious stones etc.
ILU-EBA (5 MEV, 15 KW)
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Industrial Applications of Electron Beam
Application
Energy
Dose
(kGy)
Cross
0.3-10 MeV
50-300
0.5-4
100-
Linking of Polyethylene
Thermo
250
Shrinkable Plastics
Teflon
Degradation
Curing
of Coatings on wood
0.15-0.5
20-500
Colors in Diamonds
2-10
few
0.5-4
0.5-1.0
5-10
5-10
1
0.5-1.0
0.3-1.5
10-15
1-10
20-50
0.5-1.5
20-500
0.3-2.5
10-300
Exotic
MGy
Sewage
Food
& Sludge Treatment
Preservation
Disinfestation
of Grain
Purification
of Exhaust Gases
Sterilization
of Medical Prods
Vulcanization
Graft
of Rubber
polymerization
1 Gy = 1 J/kg = 100 rad
2
2 Mev Linac / 20 kW pulse
e-beam
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Now upgraded to 5
MeV energy
Product Conveyor
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2 Mev Linac / 20 kW pulse
Prospects for industrial applications using upgraded ILU-EBA
(5MeV/15kW)
LOW DOSE (0.25kGy to 1.0kGy)
Disinfection of packed powders, cereals, grains;
Fish, Meat (in cold condition);
MEDIUM DOSE (1.0kGy -30kGy)
Medical products Sterilization; Polymer materials;
HIGH DOSE
Polymer crosslinking & degradation- O-rings, HS components; thick
polymer samples; Semi-Precious stones
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2 Mev Linac / 20 kW pulse
Type : ILU-6 Resonator Cavity, pulse
2 MeV/20 kW , scan width: ~100cm ;
single window / four window Linear scanning
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500 keV, Electron Accelerator
Electron accelerators in the energy range of
200 to 800 KeV are used for various industrial
applications like plastic modifications, surface
treatment and irradiation of medical products.
500 KeV Electron Accelerator mainly consists
of EHV supply, electron beam system,
accelerator tank, computer control system,
vacuum system, radiation shield and product
handling system.
The accelerating column
consists of three modules of large gradient
metal-ceramic tubes which can deliver beam
up to 20 mA. The electron gun is triode
geometry and uses LaB6 Cathode.
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3 Mev Electron Accelerator
3 MV supply is based on parallel fed
voltage multiplier scheme
Trial Operation of the accelerator up to 1.5
Mev, 10 kW has been conducted
3 MeV DC ACCELERATOR SCHEMATIC
3 Mev Electron Accelerator
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30
ADS PROGRAMME OVERVIEW
20 MeV
3 MeV
200 MeV
IIFC
collaboration
Demo ADS
Facility
1 GeV
Radiological safety aspects
• Ionizing Radiation
– Prompt (Vanishes with the switching off
or stoppage of the projectiles before it
gained energy)
– Residual (induced activity and the
resulting gamma)
– Silent
Target
limit
Public
1 mSv/year
Radiation worker 30 mSv/year
100 mSv/5 years
BSC
OPSRC
• X-rays from high voltage units, klystrons
• Any device with a high voltage & higher
order vacuum
DSRC
ULSC-PA
• Non-Ionizing radiation
– Microwave, RF
• Toxic, NOxious gas production
• Interlocks, search and secure system,
scram etc
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1.
2.
3.
4.
5.
6.
7.
8.
Pelletron-linac TIFR
FOTIA BARC
Medical Cyclotron Facility RMC
CCCM-Hyderabad
ILU Vashi
500keV Vashi
7MeV e- BARC
Neutron Generator Purnima BARC
LSC
Radiations from particle accelerators
Prompt
Radiation
Positive ion
Electron
Gamma
Neutrons
X –rays
Muons, pions
Photo neutrons
Bremsstrahlung
Solid
Muon, pions
Residual radiation
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gas
Radiation Safety Systems
Personnel protection systems
Zoning and
shielding
Search &
Secure
SCRAM
Door
Interlocks
Audio-Visual
alarms,
CCTV
Radiation monitoring systems
Area
Monitoring
Fixed
Beam loss
Hand held
survey
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Personal
monitoring
TLD
DRD
Neutron
Interlocks
Stop beam
High Radiation
?
Search
and
Secure
Door
opened?
Doors
locked
SCRAM
Beam on
Trapped ?
Interlock
activated
Hooter
and flash
Door key
returned
Wait for
60-90
seconds
Safety Organization
ACCELERATOR REGULATION IN BARC
BARC Safety Council
Design Stage Accelerators
Operational Accelerators
OPSRC
DSRC- AP
Working Groups
1 December 2016
ULSC-Particle Accelerator
Short term course on Particle Accelerators
in BARC
37
RADIATION SHIELDING
Passive protection against the radiation due to
•Bremsstrahlung radiation from electron machine
•Characteristic X rays
•Photo neutrons produced inside the target and shield
•Neutrons produced due to accelerated particle /
secondary beam particles.
•Prompt gamma rays due to interaction of ions or
neutrons
Shielding design to confirm 1 µSv /h for full occupancy area.
Annual Dose limit for occupational worker – 20 mSv/year
averaged over 5 years
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INDUSTRIAL SAFETY AND OCCUPATIONAL HEALTH
Industrial safety and occupational Health
Governed by
Factories Act, 1948
Atomic Energy (Factories) Rules, 1996
•First aid, periodic medical examination,
•Noise Pollution
•Appropriate lighting
•Pressure vessels, vacuum systems
•Fork lifts, hoists, cranes
•Moving machineries
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Electrical Safety
High voltage interlocks, barriers, grounded cages
Caution Signs
High quality earthing ( resistance < 1 ohm)
Provision of grounding rods
High quality insulating mats
Ventilation
Ozone production in EBA (safe limit 0.1 ppm)
Noxious fumes and gases
Air borne radionuclide such as 7BE, 15O, 13N , 41Ar
SF6 gas monitoring. Oxygen deficiency monitors should be
installed.
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Accelerators
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40
Cryogenics
Liquid helium and Liquid nitrogen are used for
cooling superconducting magnets, RF cavity.
Extreme cold can cause tissue damage, can change the
properties of material.
Asphyxiation may occur due to accidental release.
Oxygen deficiency monitors should be provided.
Proper training for handling cryogenic liquids with
necessary.
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proper PPE is
Safety aspects of Non-ionizing radiation
•
Non-ionizing radiation (3kHz-300 GHz) is used in many accelerator facilities. The
most commonly used primary sources are vacuum tubes, klystrons, magnetrons,
backward wave oscillators and solid-state RF devices. These are used to generate
Electric field/Magnetic field/Electromagnetic fields (E-field/H-field/EMF) according to
the application. While E-fields are primarily responsible for acceleration, H-fields are
used for beam manipulation (bending, focussing, scanning, etc).
•
For most accelerator installations, high performance and safety are mutually
reinforcing goals. Both human safety and equipment safety aspects should be
considered during design stage of the accelerator and its sub-systems. Health risks
associated with exposure to non-ionizing radiation-fields have been established for
various frequency ranges.
•
Exposure to occupational workers and general public are to be considered while
evaluating the safety aspects for non-ionizing radiation.
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To avoid exposure to persons to unacceptable levels of non-ionizing radiation, engineered and administrative controls,
personal protection programs, and medical surveillance should be adopted. As a first step, engineering controls should
be undertaken wherever possible to reduce device emissions of fields to acceptable levels. Such controls include good
safety design and, where necessary, the use of interlocks or similar health protection mechanisms. Some of the
measures are listed below:
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•
•
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Suitable features to minimize radiated and conducted emission in RF & Non-RF instrumentation should be
adopted from design stage itself
Proper shielding techniques for E/H/EM fields should be used
Suitable grounding schemes (with isolation between DC & RF, if necessary) should be incorporated to minimize
leakage of non-ionizing radiation.
Suitable grounded enclosures should be used for both RF and non-RF instrumentation
Compliance to relevant standards for radiated emission (RE) and conducted emission (CE) should be ensured
Proper gaskets to prevent leakages from waveguide/other joints should be used
Proper terminations (with matched RF Loads) should be used
Administrative controls, should be used in conjunction with engineering controls for ensuring safety. This includes
Proper access control
Display of appropriate caution boards at appropriate locations
Use of audible warning systems, wherever necessary
RF leakages tests, (periodic/continuous) interlocked to machine operation, should be incorporated if necessary
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Administrative controls, should be used in conjunction with engineering controls for
ensuring safety. This includes
•
•
•
•
Proper access control
Display of aappropriate caution boards at appropriate locations
Use of audible warning systems, wherever necessary
RF leakages tests, (periodic/continuous) interlocked to machine operation, should be
incorporated if necessary
•
•
References:
ICNIRP Guidelines for limiting exposure to time-varying electric, magnetic and electromagnetic
fields (up to 300 GHz), Health Physics 74 (4):494‐522; 1998
ICNIRP Guidelines, pp 498-508
ICNIRP Guidelines, pp 512
ICNIRP Guidelines, pp 513-514
•
•
•
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Conclusion
• There are eight accelerator facilities in BARC , complies with the guidelines
and recommendations of the Unit Level Safety Committee-Particle
Accelerator (ULSC-PA), the Operating Plant Safety Committee (OPSRC) and
the BARC Safety Council (BSC).
• ULSC-PA reviews all the facilities periodically.
• All the facilities are observing high level of safety standards.
Thanks
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Dr Herb and Jim Ferry
developed Pellet Charging
system.
Pelletron –Linac Facility
Typical module
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Quarter wave resonator
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