Radiat. Phys. Chem. Vol. 18, No. I-2, pp. 313-322, 1981
0146-5724/81/070331-10502.00/0
Printed in Great Britain.
Pergamon Press Ltd.
LOW ENERGY E L E C T R O N BEAM F A C I L I T I E S Roy M. E m a n u e l s o n High V o l t a g e E n g i n e e r i n g C o r p o r a t i o n F.C. Box 416, South Bedford Street; Burlington,
Massachusetts
01803,U.S.A.
It is a p l e a s u r e to address the Third I n t e r n a t i o n a l M e e t i n g on Radiation P r o c e s s i n g and to have an o p p o r t u n i t y to discuss some exciting new trends in low-energy e l e c t r o n b e a m process equipment.
I say exciting,
b e c a u s e these new p r o d u c t s and ideas offer industry practical integrated, customers
turnkey facilities.
In the future,
choices
in
less will be required by
in the p l a n n i n g and c o n s t r u c t i o n phases of the electron beam
facility. It is e s p e c i a l l y Japan.
appropriate
to be able to introduce these ideas in
The license and technical assistance agreement which my company
has w i t h our affiliates, electron accelerators
Nissin High Voltage,
to one m i l l i o n volts.
concerns c a b l e - c o n n e c t e d The products
and ideas that
I will d i s c u s s today cover this voltage range and are an extension to this basic technology. There are two approaches to the i n s t a l l a t i o n of any low-energy electron b e a m system.
The first choice concerns
those that have steel or lead f a b r i c a t i o n s and u n d e r b e a m h a n d l i n g equipment. packages,
"self-shielded"
designs --
integral to the a c c e l e r a t o r
These are free-standing,
complete
and g e n e r a l l y do not require b u i l d i n g modifications.
o c c u p y a m i n i m u m of floor space and, into e x i s t i n g p r o d u c t i o n
lines.
in many cases,
They
can be i n c o r p o r a t e d
The second choice is a c o n s t r u c t e d
facility d e s i g n -- the fabrication of a concrete enclosure or treatment room to house the a c c e l e r a t o r and u n d e r b e a m handling equipment. concrete e n c l o s u r e s
can be constructed
b u i l d i n g and can be r e l a t i v e l y
These
in the floor space of an existing
inexpensive
in their m o d u l a r design.
At the Second I n t e r n a t i o n a l M e e t i n g on Radiation P r o c e s s i n g Miami, we reported on two s e l f - s h i e l d e d designs.
in
One design was specifi-
cally for e x p e r i m e n t a l or laboratory use and had a rating of 300kV-10mA (Figure i). 300kV-100mA
The other, p a c k a g e had h i g h - c a p a c i t y output specifications (Figure 2) to meet the c o m m e r c i a l
industrial e l e c t r o n b e a m curing applications.
Since the last conference,
we have c o m p l e t e d the i n s t a l l a t i o n of several more 300kV systems: 3 0 0 k V - 5 0 m A system, b e a m scanners,
two 3 0 0 k V - 1 0 0 m A systems equipped
and a n o t h e r
with 96-inch
300kV-15mA research system 313
of
line speed r e q u i r e m e n t s of
(Figure 3).
a (2440mm)
314
R.M. EMANUELSON
Figure i. 300 kV S e l f - S h i e l d e d Electron Processing System
Figure 2. 300 kV100 m A E l e c t r o n Beam Curing S y s t e m
Figure 3. 300 kV15 m A E l e c t r o n Beam System for Research
!iiiiiiii¸ll
!i¸¸¸!¸~ii! ¸¸
Low energy electron beam facilities This year it is a p l e a s u r e features of a new 550kV-40mA, cally designed
Figure
for me to introduce and d e s c r i b e the
self-shielded,
4.
550 k V - 4 0 m A S e l f - S h i e l d e d
In this system, power is transmitted
axis,
electron b e a m system specifi-
to process g r a n u l a r or powder materials
the a c c e l e r a t o r by means of a flexible, termination
315
in bulk
(Figure 4).
Electron Beam System
from the ICT ® power supply to
high-voltage
cable.
The cable
at the a c c e l e r a t o r head is made at right angles to the beam
e l i m i n a t i n g the cable bend radius h e a d r o o m r e q u i r e m e n t
and permit-
ting i n s t a l l a t i o n of the assembly
in normal ceiling height areas.
system is e q u i p p e d w i t h a 36-inch
(915 mm) beam scanner.
The u n d e r b e a m p r o d u c t handling equipment steel, belt conveyor.
is a continuous,
The belt w i d t h is one meter,
tension sections,
The conveyor
r o t a t i n g brushes
tus, and a s s o c i a t e d material the basic structural
b e a m scanner,
0.25 mR/hour.
This p e r m i t s
to be c l a s s i f i e d
tracking appara-
The frame also provides lead shields w h i c h sur-
and conveyor.
levels in all areas a c c e s s i b l e
(4.5 to
the drive and
for cleaning the belt,
support for the removable
round the accelerator, radiation
frame a c c o m m o d a t e s
handling equipment.
stainless
and the conveyor line
speed is a d j u s t a b l e w i t h i n a range of 15 to 150 feet per minute 45 m e t e r s per minute).
The
The shields reduce
to personnel
to a m a x i m u m of
the w o r k i n g area adjacent to the assembly
as "unrestricted"
or "non-controlled."
316
R.M. EMANUELSON In this specific p r o c e s s i n g design for granular or powder materials,
the bulk m a t e r i a l
is p n e u m a t i c a l l y b r o u g h t to a d i s t r i b u t o r
the inlet of the endless belt.
The m a t e r i a l
the w i d t h of the belt in a u n i f o r m thickness. ment,
the p r o d u c t g r a v i t y - f a l l s
removed
After electron b e a m treat-
from the conveyor tension section and is
for bulk storage by another p n e u m a t i c
and c o u n t e r - w e i g h t e d
located on
is d i s t r i b u t e d evenly over
system.
inspection cover interlocked
There is a hinged
for safety w h i c h is
located near the inlet, p e r m i t t i n g visual o b s e r v a t i o n of p r o d u c t Twelve other removable of the conveyor
cover plates,
frame, p r o v i d e access to the belt and its drive and
t e n s i o n sections.
Two shielding clamshells
Access to all scanner components removed.
surround the beam scanner.
is p o s s i b l e w h e n these clamshells
All access covers are assembled w i t h redundant
v e n t i n g o p e r a t i o n of the equipment pipes,
in an unsafe mode.
requirements
This s e l f - s h i e l d e d
pre-
cooling air, and
Of the system. electron p r o c e s s i n g
new, c o m p l e t e l y automatic control
Figure 5.
are
interlocks,
All conduits,
and ducts are p r o v i d e d to meet the cooling water,
ventilation
flow.
m o u n t e d on the top and side surfaces
Control Console
b r o u g h t to its full p e r f o r m a n c e
system
system is supplied w i t h our
(Figure 5).
The system can be
for E l e c t r o n Beam Process System
rating by simply turning a f o u r - p o s i t i o n
key switch through all positions.
Ramp circuits a u t o m a t i c a l l y
raise b e a m
c u r r e n t to a preset level at a typical rate of one m i l l i a m p e r e per second. These circuits also provide p r o p o r t i o n a l assuring a uniform,
control of conveyor
speed, thus
p r e d e t e r m i n e d p r o d u c t dose in all o p e r a t i n g c o n d i t i o n s
Low energy electron beam facilities S h u t d o w n sequence is in two modes. tage are d e c r e a s e d circumstances,
Normally,
317 beam current and vol-
at ramp or V a r i a c speeds, but in certain emergency
main power is immediately disconnected,
removing all power
to the system. Interlock trip-outs can initiate a shutdown sequence in either the ramp or rapid mode. lock has tripped.
In any case,
an LED d i s p l a y indicates w h i c h inter-
L a t c h i n g relays are used to assure that the LED d i s p l a y
remains d e - e n e r g i z e d even when there is a m o m e n t a r y trip-out. functions
are also a c c o m p a n i e d by audio alarm,
o p e r a t o r to a p o s s i b l e system malfunction. vision for a c c e p t i n g up to 40 interlock available
for c u s t o m e r - s u p p l i e d
Interlock
alerting the equipment
The control
functions.
station has pro-
Eight of these are
equipment.
The ICT ® control system has been designed to interface with several commercially
available data loggers.
Output p a r a m e t e r s
the ICT ® control circuits include terminal voltage, coil currents,
and p r o d u c t speed.
available
from
beam current,
scan
Other parameters d e s i r e d by the cus-
tomer can also be included. A data logger c o m p a t i b l e with the customer's needs can be selected, packaged,
and i n t e r c o n n e c t e d
as an option.
Fixed or adjustable
logging
f r e q u e n c i e s , typically ranging from one second to one year, are available. Log records can be kept in the form of hard copy, magnetic Line item data retrieval processing
tape, or both.
from the log history for v e r i f i c a t i o n of past
runs is an a t t r a c t i v e option available on some automatic data
loggers. P r o v i s i o n is also provided
for external computer control.
and beam c u r r e n t control can be initiated by relay contacts computer. levels.
Zero to ten VDC reference signal d e t e r m i n e s The c o m p u t e r can also provide the o v e r v o l t a g e
Voltage
from the
the operating and o v e r l o a d
signals to interrupt the system in case of an overload condition. All o p e r a t i n g controls are m o u n t e d in a NEMA-12, access,
dust-free,
industrial enclosure.
single door, dual-
The solid-state w a v e f o r m genera-
tor and the v a c u u m pump power supply are m o u n t e d within the cabinet. air w i t h i n the e n c l o s u r e c h a n g e r to all c o m p o n e n t s
for cooling.
Digital panel meters d i s p l a y operating voltage, voltage,
and p r i m a r y currents.
d i s p l a y panel,
The
is c i r c u l a t e d through a w a t e r - c o o l e d heat ex-
These meters,
load current,
primary
the LED interlock function
and the p e r f o r m a n c e of the v a c u u m system and scanner wave-
form g e n e r a t o r can be o b s e r v e d through t r a n s p a r e n t windows m o u n t e d on the front console enclosure.
These are the only controls normally available
to the o p e r a t o r of the system. In the design of this p a r t i c u l a r terials,
the electron a c c e l e r a t o r
from the room e n v i r o n m e n t to minimize motors,
switches,
system for granular or powder ma-
and the v a c u u m ion pump are isolated the risk from dust explosion.
and e l e c t r i c a l devices
All
supplied with the a c c e l e r a t o r
318
R.M. EMANUELSON
and c o n v e y o r are d u s t - i g n i t i o n proof, m e e t i n g the r e q u i r e m e n t
for Class
II, Group G, D i v i s i o n
and conveyor
I areas.
assembly can be installed room height of 13 feet At full output,
The s e l f - s h i e l d e d a c c e l e r a t o r
in a floor space of 20 feet by 10 feet and a
(6 meters by 3 meters,
4 meters high).
this system has a p r o c e s s i n g capacity of 10,000
pounds per hour at one m e g a r a d
(4000 kilograms per hour at one megarad).
The p r e s e n t
selling price inclusive of special engineering
tory tests,
spare parts,
charges,
fac-
and supervision of i n s t a l l a t i o n is a p p r o x i m a t e l y
$500,000. The technique of jobsite p r e c a s t i n g as tilt-up construction,
best describes
stallation of a packaged, reinforced,
large wall units,
commonly known
the second approach to the in-
low-energy e l e c t r o n b e a m system.
A single-cast,
concrete panel is the basic b u i l d i n g block for this design
(Figure 6).
/
CONNECTING /PLATES
1800 mm
e
72"
i~ q,i
i-
el
/ -'~'BOLTS
I"
~,8Omm = 15" "'-
ELEVATION
IO40 mm 42"
J=380 mm " 15"
v i
CROSS SECTION WEIGHT OF REINFORCING STEEL-lOOkg (230 di) WEIGHT OF CONCRETE PANEL- 6000kg (13,300#)
Figure 6.
Basic Concrete Panel Block.
The c a s t i n g ' b e d w o u l d normally be the floor slab of the building. Precision
fabricated
steel molds assure u n i f o r m panels
(overlap matching)
and, at the same time, give an a e s t h e t i c a l l y p l e a s i n g surface finish. Each panel requires weighs
13,300 pounds
3% cubic yards
(2% cubic meters)
(6 metric tons).
livered on site in our area of the United States F o u r t e e n panels are needed for a 10½ by 13 foot room having outside wall d i m e n s i o n s meters).
is $45 per cubic yard. (3 by 4 meter)
of 15½ feet by 18 feet
treatment
(4% by 5½
F o r t y - t w o cubic yards of concrete are required for the walls,
w i t h an a p p r o x i m a t e truck carries time.
of concrete and
The p r e s e n t cost of concrete de-
"off=the-truck"
value of only $2,500.
i0 cubic yards, p e r m i t t i n g
A full concrete
three panels to be cast at one
Low energy elec~on beam facilities O r d i n a r y cr average concrete,
319
having a m i n i m u m c o m p r e s s i v e
of 3000 psi, p r o v i d e s the required density.
strength
Inserts for attaching panels
to each other and for e r e c t i o n of the panels are included at the time of casting.
The concrete
bubbles
should be vibrated during p o u r i n g to eliminate air
in the mixture.
be c o m p l e t e l y
smooth.
smooth finish. before removal be a s s e m b l e d
The surfaces
in contact w i t h the steel mold will
The top or exposed surfaces can be trowelled
for a
The p r e c a s t panels must be allowed to set for five days from the molds.
Figure 7 illustrates how the panels can
into a w o r k i n g electron beam facility.
I
4,5m 15'- 6"
T
r ~:~ :~::.:.~.i~ ~:~ ~. J~
El,o
2.9m 9'6" "_,
~-J i
FLOOR PLAN
H FRONT ELEVATION Figure 7.
Typical
SECTION THRU VAULT Working
Electron
Beam F a c i l i t y .
The prime common objective in the design of these panels is to provide adequate radiation and i n s t a l l a t i o n panels,
shielding.
However,
other useful e n g i n e e r i n g
functions are included in the p r e f a b r i c a t i o n design of
and this reduces the costly special e n g i n e e r i n g
and a r c h i t e c t u r a l
fees n o r m a l l y a s s o c i a t e d with a facility construction. For example, and devices semblies,
one panel can be cast to incorporate
for supporting the a c c e l e r a t i o n
a beam drift tube
tube and beam scanning as-
thus e l i m i n a t i n g any need for a separate support structure with-
in the facility.
In this approach,
the concrete
shielding w h i c h surrounds
the drift tube also confines any escaping x-rays to the small emittance angle of the beam tube section. Minimizing tube makes
the ionization
shielding
the a c c e l e r a t i o n
simple.
levels in the region of the a c c e l e r a t i o n This isolation also reduces
tube terminal and its tank,
h o l d i n g p e r f o r m a n c e of the system.
and enhances
leakage b e t w e e n the voltage-
320
R.M. EMANUELSON Also p r e c a s t
into this panel are the ducts for w i n d o w cooling air
and room ventilation, the cooling water
the conduits
needed to meet the a c c e l e r a t o r A n o t h e r p r e c a s t panel tinuously m o v i n g p r o d u c t s the p r o d u c t
for all e l e c t r i c a l
inlet and outlet pipes.
connections,
and
No further facility design is
i n s t a l l a t i o n requirements.
is fabricated to p r o v i d e the means to and from the treatment
is a thin film or web.
zone.
N a r r o w stainless
for con-
In this case,
steel slits placed
near the floor and ceiling meet this objective. Physical d i m e n s i o n s satisfy p r o t e c t i o n the m e c h a n i c a l
and geometric c o n s i d e r a t i o n s
requirements.
are important to
In most cases the product
itself and
e q u i p m e n t required for p r o d u c t h a n d l i n g will restrict ac-
cess to this area. Access to the t r e a t m e n t room in this design is through a short labyrinth.
Two special p r e h u n g personnel
precast panels to p r o v i d e additional
access doors m a t c h w i t h the
safe access to the treatment room and give the
required p r o t e c t i o n
against scattered x-rays.
All p r e c a s t panels are erected on site by riggers, hydraulic altered
lifting equipment.
using standard
The size of the treatment room can be
in increments of 9½ feet by adding or subtracting two identical
p r e c a s t panels to,each wall. struction,
Because of the m o d u l a r nature of the con-
these changes can be made at any time.
that the entire
facility can be disassembled,
case with general
It should be noted
w h i c h is certainly not the
reinforced c o n c r e t e construction.
Large concrete blocks have p r e v i o u s l y been used in the c o n s t r u c t i o n of e l e c t r o n b e a m facilities.
Figure 8 shows the i n s t a l l a t i o n of a 2500kV-
50mA ICT ® E l e c t r o n P r o c e s s i n g
System at High V o l t a g e Engineering.
Two
rows of blocks having d i m e n s i o n s of three feet by three feet by four feet high
(i m e t e r by 1 meter by 1.2 meters high) were used in this i n s t a l l a t i o n
(Figure 9).
Figure 8.
2500 k V - 5 0 m A ICT ® Electron P r o c e s s i n g
System.
Low energy electron beam facilities
Figure
The p r e c a s t choice
of o t h e r
thickness two)
9.
panels
of m a t e r i a l
in Table
can,
shielding
Concrete
most
intensity
considered
or cast
thickness
from a
(the
by a factor
in s h i e l d i n g
of
designs
is
I.
300kV 500kV 750kV 1000kV Ref.
value
be fabricated
the r a d i a t i o n
commonly
I.
Concrete
From this
Construction.
The h a l f - v a l u e
Table
material.
Block
in principal,
materials.
to reduce
for the m a t e r i a l s
given
Cast
321
table
This
thickness
Steel
1.4 1.5 1.7 1.9
Lead
.25 .35 .50 .60
.05 .13 .24 .32
NCRP-H50
it can be seen that
is p a r t i c u l a r l y is much
lead
is an e f f e c t i v e
true at 300kV and
less than the relative
500kV w h e r e
densities
shielding the half-
of the shielding
materials. Nevertheless, tion of a t r e a t m e n t and
fabrication
posites. job-site
full panels room w o u l d
costs
if they were
By comparison, precast
projections (estimated
panels
costs
constructed
for concrete
or for solid m a s o n r y
for the typical "in-house"
of the size we are d i s c u s s i n g be p r o h i b i t i v e l y
prefabricated
construction)
expensive
for construc-
in m a t e r i a l
of lead or lead-steel
construction, units
facility
are as follows:
either
are minimal.
for Cost
under d i s c u s s i o n
com-
322
R.M. EMANUELSON F o u n d a t i o n work Steel Molds (three) Cast Panels (fourteen) Special Prehung Access Doors P r e s t r e s s e d Roof Panels E r e c t i o n Costs T r a n s p o r t a t i o n Costs (local)
* $3,000 5,000 3,000 3,000 3,000 1,000
TOTAL
$18,000
• S o i l - b e a r i n g capacity will d e t e r m i n e should be evaluated separately.
Special
shielding design costs,
ing fees are minimized.
foundation costs.
architects,
In most cases,
Each i n s t a l l a t i o n
and c o n s u l t i n g engineer-
the cost of a p r e c a s t panel
facility e q u i p p e d with an e q u i v a l e n t electron b e a m system would be less than a specially designed, In conclusion, a self-shielded,
self-shielded
single-purpose,
dedicated
w h i c h are integral to the a c c e l e r a t o r greatest extent possible,
little effort by the customer facility,
Engineering,
the customer's
system,
To the requiring
in order for them to be integrated
into an
The other type of system is a "prefabricated"
space flexibility
planning,
involvement
One is
having lead shields
and u n d e r b e a m equipment.
best suited to the higher voltage
a p p l i c a t i o n s w h i c h require ment.
from w h i c h to choose.
these systems are turnkey in nature,
existing process environment. panel
system.
there are two systems
levels and to those
for process u n d e r b e a m equip-
and p r e c o n s t r u c t i o n
in the i n s t a l l a t i o n
techniques minimize
in both systems approaches.