Low energy electron beam facilities

Low energy electron beam facilities

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 ...

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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.