ww

portional counter , 80, or by calculation feom the
measured neutron flux and energy distribution [81
doensrey neutron fk i toe on 10 ke) aoa,
a new fox $s usual or
protection because the biological effect per neutron is small
compared to that for fast neutrons, and the intermediate

neutrons are ited in the human bi
feutrone are quickly moderat usual ody, bo

measurements is a boron counter in a moderator, such as

aes punter 2, 88] or cartain survey ts
‘the Souler Baise 4 also useful for Det-hattion ond
asta flux measure,

8, Thermal neutrons, ‘Thermal-nenteon flux may: be de-
termined by absolute measurement of the induced! radio-
activity in any one of several elements [25, 85]. ‘Boron-
walled ionization chambers or counters may be calibrated
by? means of foil activation.

be measured in

Gamma ray: papers dose may
cathonwalion Ghatabars wi often have onl a: sl ht
responge to neutrons (which must be carrecte for).
cause the interaction of neutrons with tissue can produce
gamina rays, a precise getermination 0 of the dose réquires

appropriate toms. Commonly olen lange pea
meters and Geahmetors cannot ber cannot be used jen bers
of neutrons are present as they possess consider:
unimown neutron sensitivity.

5. Persownel monitoring, Area, monitoring of neutrons

tht nevkrong, becgve eft nine gumaray it for
fast neu! because often neither gamma-ray poe

cleat, dosimeters give sufficient information to
ate 2 dose, Fast-neutron nuciear-track fil i badges 136)
are useftl in case of accident and, although 2 rather ingansi-

B. Calibration

With most neutron-monitoring instruments it is ad
that the instrument be calibrated ad requentiy in a

ux. Extremely large errors gible -with
many commercial Sutrements unis unless erly calibrated.
ethog for ie the’ ray 2 portable

radioactive nearon § pies calibration ouree. A primary imery standard source of
@ laboratory for total neutron vamigeion
rate Dy the National Bureau of Standards.

14

Radioacti: sources may also be calibrated for
dose rate ‘at a neva e distance using a fast neutron dosimeter
calibrated with an internal alpha source source, [20] or & or calibrated
with monoenergetic neutrons. Known
calibration may be obtained ws the Samal f standard
source in a graphite “standard. 7}, or by use of a
moderating metry to produce 3 th agi neutron. ed
flux such a3 the National Bureau of Stentseds standard
thermal-neutron density [88].

Appendix 5. Neutron-Capture Gamma Rays

Table 6 summarizes gamma-ray energies encountered in
neutron capture.

Appendix6. Shielding Calculations and Data

'The same fundamental safety factors that were described
$9) for eum rays apply to neutrons: (a) Distance
frre sousen (0), ie of arom, 8 (emma
iel ex”
neutron sources aidtex considerably, they will be treated
separat

Reactors’

‘The neutrons from reactors come from (a) the fission
process (prompt neutrons) and (b) radioactive nuclides
produced in fission (delayed neutrons).

Prompt Nentrons from Fission

Prompt neutrons from fission are produced st all ener-
gies up fo about 17 Mev, distributed as shown in gure 16.
More accurate figures are given in table 7, The attenuation

degradati panes ished te re ateoe Ie

ion, d or the
ely d 80 that its total escape path is significantly’
increased. Following degradation, many successive colli-
Saas Dee coe eer, Seams

are

general cross sections decrease with inereasing energy,
‘aus cies Saas of clans 6 6, egmulleted, webiet ees hemes &

sionig enon Set Wt be ie iatake Pox qaltanding the teats af tall
et]



Before Decontamination

Fourth Floor

Room 403 .

= 20,000 c/m air duct
s 30, C00 c/m and 1.0 mr/hr contact windows and Frames
s §,000 c/m and 1.5 mr/hr contact wali molding .

Room 418

= 60,000 c/m and 10 mr/nr contact windows and frames
-2=6 me/nr contact on watt molding
> $150,000 c/m alr duet

Room 410

= 10,000 cY¥m to left door 6 ft? area
2 mr/hr contact spot floor by door to Room 411

Room 411

Q.8 mrfhr contact floor srea by room entrance ~2

Auditorium Lobby Area

30,000 c/m and 0,5~8 mr/nr windows and frames
12,000 ¢/m marble room molding

S 315,000 ¢/m rug

< 60,000 ¢/m major portion of terrazzo floor

Fr


&

taken over 100 en? areas. A‘) smears read less than 10 & counts/ -
minute which $s the level permitted at RBS.

Tables and charts summarizing our findings arc attached,

To the best of our knowledge, all the butidings in the downtown comp} ex.
are now free of radioactive contamination, This is not to state that
there may not be 2 small spot here and there that has escaped our
detection, but we can unequivocally state that there Is absolutely no
radiation hazard of any sort.

Four weeks were spent In deconteminating the bullding. This amounted
to approximately 1608 man hours, 50% contributed by the Health Paysics
Section, 25% by Plant Diviston courtesy of Mr. Morton Kelly, and 25%
by GSA, Approximately 100 55-ga)lon drums were fllied with radioactive
waste. Approximately $1500 was spent for suppties such as drums which
cost $750. In addition, 3 large number of respirators, coveralls,
shoes, paint, towels, etc., were consumed». The Health Physics Section
has absorbed the cosi of the decontamination as far as suppl tes ans *
equipment are concerned,

Attachments


rmneia
i
+ r
» =f Stee
——
‘ “CTR :
2» : Naina 1
40 L
THERMAL Of = OR Og tk 2 S tok’ 20 30 fobw 200 50D tev 5 1OMer
. + NEUTRON ENERGY

Fioors 18, Flux of neutrons to deliver the stated dose rate as w function of neutron energy.

"
* 4
N + ew
* Todt A) EN
ot seat -
° Se Sioa Cy @ lew]
e . £: bs ALS
8 eC ah folef fap | Ficurs if. RBE
ry At TPT eR? PD '=D.JEs) 08
* 7 a Tf tome | Te) ona of depth
e irene » mM
a it te wert ce
. [R008 tor *
ei WW 1 ra
Le a a
| .
’ "ODOC er é red ol ste.
° im
s $s J is 2 a 3


where

p—power density in core (watts/cm*),
Zrg=macroscopic removal cross section of core
material, calculated as above (cm):
Texghield thickness (cm).
=,maverage macroscopic removal cross section
for shield (cm HS
==(1/T) C2) + (80) st2edac «1.
(3:2) ==product of macroscopic renioval cross sec-
Tagen” 4 Halekness w for the th shield

5.4X10%= (7.510 fission neutrons per x joule) xh,
geometrical factor) + Cn 0 neutrons/
em*/sec per rem/hr).
Fuageometric factor taking account of the core
shape, as follows:

‘mon tor 8 large flat core surface adjacent to

‘==a/(T-+-a) for 9 spherical core of radius a.
e=[a/(T-40)7% for a cylinder of radius a,
measurement at midplane.
For small cores of whatever shape the @ formuts for a
diameter (og, commer vornes) ae fal led the maximum
ter (e.g., corner to corner) dm is the following

sr

tay (9)

Delayed Neutrons
Delayed neutrons are produced from certain radioactive
nuclides the fission products. The half lives, ener-

gies, and ylelds of the dominant emitters (groups) jare

ven in table 10. They are not important by comparison
with the pr fission neutrons, but for cases in which
the fission lucts axe removed from the reactor to regions
outside its shield Shortly. after produced they may
be very important. Examples of such removal are experi.
mental fuel Joops and in oe ate sample handlers in

fission takes pla Bikes place

ok the only really satisfactory shields
are For delayed ne materials, and the effectiveness depends
only on the hydrogen thickness of the shield. Because the
neutrons are of too low energy for inelastic. scattering, ele-

82

Taste 10, Delayed neutrone from feston products

9X10, 2H,
he . gields | Removal
Group {Halt Ute| \-- Decty | Energy | ¢1, Dose per Beedle ile eocrie ot
usr | py | kydrogen
|) kee rhe pee Barne
ae 10" nts 7 r pe
zo | saxie# 42 1
‘ me] SPO") ae] at ta
, ase HE} at Be a78 9
* wer 80 m2 |" 87 63
wee sae 182.85 | 1002 fom

ments other than are relatively ineffective and
fyareten for each energy i also given Ia table 10,
en
by The dose due to the delayed deutrons 4 is just the sum
of the contributions from several emitters:
Dew DADAD ADH». (10)

here 1, 2, 8, ate., refer to the different of delayed
eu trond. trong. ‘The contribution from one nt rome calculated
2s fo

Dy (roms tx) — Sie, qu)

R==distance from of delayed ne
source tp aso wnere Das 0 be dolor

T—shield thickness (cm).
Fermaverage, rage, macroscopic removal cxoss section
VE cone ection
_ removal cross si
Cet) Pr lelnean for the i shield layer
g=dose,

neu-

Roas/en so for the eed fix, (new.
Bene group 1,

Sy=source aoe, of neutrons
from group

common case of a yraninm bearing liquid (or

wi or the circulating into and out of a reactor, the source,

88


Before Becontaminatian
:

Third Floor

Room 3154

S 30,000 c/a baseboard
= 20,000 c/m wood ficor

Room 315 .
15,000 cfm eleven Spots on floor
Room 3164 .
S 75,006 c/m and $20 mrfhe contact floor
S 20,000 c/m and $20 mr/nar window ang frame
S 75,000 c/m baseboard
s 5 mr/hr contact a}? wal lboards and coor frame
Room 316 .
= 8,000 c/m end <10 mr/pr window and frame
< 5 mr/hr contact all wal lboards and door frame
S 80,000 c/m baseboard
< ° § mrfhr contact Floor
Room 317
S 6,500 c/m and <5 mr/hr window and frame
s 3 mr/hr contecr al} wallboards and door frame

S 32,000 c/m baseboard
< 3 mr/hr contact Floor



i

op ee a we

ar

ry

«

Faure 48. RBH dose (rams) from 5-Mev neutron beam.

44



2

Since none of the araas in the East Bul iding were-controtled areas and
since they had been used for other purposes since 1952, ao further
surveys were made In the East Building. The bulldings were subsequently”
turned over to GSA who in turn leased them to the Olstrict of Columbla.
At this polnt a D.C, radiological monitoring team found the CRM signs
and made a survey. They fourd that the atric had a large number of spots
which indicated @ contamination to the extant of 100,000~1,000,000
counts/minute. These were fixed and could not be removed by dry smears.
Trey also found a few small aregs in the hallways that contained over
100,000 & counts/minute. The question of who was to Clean this mess
arose. Mr. Morton Kelly very kindly supplied three laborers for a perlod
of two weeks and a clean up was begun. ’

The first order of business was to determing the 222, content of the
air. If there were excessive emounts gf 28pq In the bulldings then
there should be an elevation of the 22: Rn and its daughter products.

Airs: les taken _oy, $3 da. the buliding and In the vartous rooms
found contaminated. The 222, and daughter products were found to be

pa

approximately 2x oh8 ptt/mi of atr in the outside alr and from

2- 8x 10710 ucismi Inside the building. The International Commission
on Radiological Proggetion has recommended a maximum permissible .
concentration for An and its daughter products of 3 x 107 uCl/mi
for the popypetion at Jarge. The ICRP recommends a level’ of no more
than 1 x 10° uci/ml of alr for paople who live Jn the environs of a
plant which gives rise té these radioactive matertals, and a Jevel of
3 x 10°S uci/mi of air for workeggoin | plant where such materials are
generated. On the bas!s of the Zen che building air was certainly

_ safe from + radiological contamination. tn ne case was any long lived
@ activity found In the alr samples which were taken by means of
Staplex air samplers and analyzed eccording to the method of Or, John
Harley of the Health and Safety Lab, New York Operations Office of the
Atomic Energy Commisston. .

Ail floors were scrubbed with. liquid- detergents using wire brushes.
Where neGessary, palnt remover was used. The levels were brought down
to below 5,000 C counts/minute. At thls point the floors were painted
with a lepdopigment paint. The lead pigment was used to diluce the
Tsotopic Pb, After painting, no &@ contamination could be detected
except in one or two small areas. These areas were repainted. “AW
the walls were vacuum cleaned and al} contaminated equipment was
removed as radioactive waste.


TABLM 6. Capture gamma rays*

Right nergy

8.66

a

RE RE SMES E

oe

58

a8

"Thane 7
ye Be Ht ay tet Prom PS. Mittainan ant B.A. Liedtke, Nusieomte 12,

Kio

LA

pi
l

2 ~ aN

° & ‘ € ry 10 Te “" 16
ey wer

Figures 16, Distribution trons,
Muynber of neutrons yer St Por Lie org gibt enorsy.

the neutrons ced, at higher energy have the, est
chance of pen ion. Balancing this is < distri-
pution in which the lower energies lominate. For most
shields ‘the neutrons need at me & Moy are post

\g penetrat they may ve a <}
el en Se eaatce end hance emerge at lower
energy. .

A ified calculation of attenuation is made on the
basis of neutrons at about 8 Mev. Some allowance fs
necessary for the neutrons that have collided but still es-
cape, a factor usually called the buildup factor. This is
taken account of by a competisating factor

7


[85] G. W. Tittle, Nucleonies 8, No. 6, 5 (4951); 9, No, 1, 60 (3981).
[86] J. &. Cheka, Nucleonics 12, No. 6, 40 (1954).
[87] “Dy ke y Haehes, Pile Neutron Research, (Addison-Westey,

{88} J. A, DeJuren and H. Rosenwasser, J. Research NBS 52, 98
1854} RP2477.
[89] Protection, spines Handbook 64 G96). om

{401 @._O, Baldwin and F, R, Hider, Genera} Electric Research
‘Laboratory Report RL-802 (1940),

[41] J. S, Levinger, Nucleonics 6, No, 5, 64 (1950).
[42] 3. S. Levinger and H. Bethe, Phys. Rev. 78 115 (1950),
[43] G. C. Baldwin and ¥. R, Hlder, Phys. Rev, 78 76 (1950).

WASHINGTON, March 29, 1957.
RU. &, GOVERNMENT PRINTING OFFICE, tw67--492002

SI menue

.



‘we
where
oeemicroscopie xemoval cross section (barns),

p—density (g/cm),
A==atomic weight.

It will be noted that 2./p is a dependent
the microscopic muclea? guantity, depen - Soest

yoying f function of the atomic weight, which

figure 17. this curve the 1 ia
re remov:
be,gbtained for any element across 8 man
The macroscopic removal cross section for a material of

several elements elements ic obtained by ‘by aime summation over &

e
= ne pect 3) rte (2)
where
(35) —vale from figure 17 for element 1 of:

compound, (cm*/g), ete.
pendensity of clement 1 (g/em*), ate,

Examples Find 3, for CaCO,; density = 2.711, molecular weight

ee —_

Bement a ° Erle | (Dep dacte
glows

Go| 40.08 | 42% x ont—s007,| 09242 | ores

Ou} 12.01
On| 16

32.01 4
to0.00 X 2.711 == 0.825 0510 0166

X18. arri=sg99 | 0810 | 0688

Total... 0.0962
Ex, CaCO. = 0.0062 cm

concretes,
iis eee a
results are  auiarteed £0 materials.

for several common
«HRs ors of the soon s Sfued fe tg volume fa
take place, and the shield is the material

Tawus 8 Caloulations of neutron removal oross sections (Ex)

ee
ee A | Bye B
Bartyex block conorete
olon?
es bet Sar ert]
16.0 A Oh 044i
24,83 0.03 3S
49.08 a a a
eis) tite, 8 ‘Sune
24°40 “Den a Sais
na 03 ace ‘Boat
ake SS ‘Rat Bee
ee 8.404, 0.0946.
Ordi
16.0 0.0461, 0.0468
ie Rid ae
8B. 2 004
8 yom age
12.01 air af
eB a 8 Ey
ahs @ 20
4 0.0042
TABLE 9, Macroseopin newiron removal croas seottone (Z,)
and aitenuatton lengths "seme shielding
and reactor ‘nuntertate
Material rattopoittod “oa
ones om
OR, Ri
cg it

exterual to it, Including reflector, pressure shell, if any,
‘tie Sose external to the field is now eslenlated to be

__ PF
D (rams /ar) 54X10" po or, (8)

81


3

lt was then decided to check all the rooms in which radium had at one
time been hendied, Hot spots reading as high as 20 mar/hr gamma Loe
radiation were found in rooms £98, 316A, 316 and 317. Further surveys
revealed local contamination in other rooms, not used for radium
work, as well as extensive contamination of the fourth floor hal way
and, even more surprising, extensive contamination of the hallway tn 7
front of the fourth floor lecture room. Ho contamination was found
in the lecture room itself. Investigation revealed that one of the
physicises measuring radium had periodicaily vented the radium ampoules
through the window of room 418, The Windows next to the Jectuce hall
were usually kept open for ventilation In the spring and Summer, so
that the alr exhausted out one window swept back into the hallway
through others, . . .

To remove the contamination in room 418, the floor, floer moldings,
exhaust dust cover, windows, doorway frames and doors had to be :

removed. The air duct was Vecuumed and painted. On the third floor

the floors in ropms 316A, 316 and 317 and a partition between 316A and

316 had to be removed. A 3~inch thick concrete floor had tobe removed

from all three rooms since It was highly contaminated, Fortunately, °

the permanent concrete sub-floor was not contaminated so that no

Structural demolttion vas necessary. The floor moldings, some of the . .
window Framing and doors had to be removed. mes

Since the hallway Floors were contaminated, an outside contractor was
Rired to dritt up parts of the floor with a Jack hammer. Some of the
Floor on the fourth floor, especially the one in front of the lecture
hall, had to be removed, Approximately 3 Inches of concrete were.
removed, In the attle 3 Sections of floor ware removed with a jack

hammer and replaced with Sakrete mix.

After alt the rough work had been done, and all rooms and hallways
vacuumed with special absolute Flicered vacuum cleaners, a_10-man
janitorial force came ia to wash down al} the floos and haliways in

the bullding,

After the clean Up, a recheck was made of the 2222, and daughter =i
products, The radon content in sir outside the bullding was 8.3 x 30’
uCt/mi of air while It varied From 1.5 - & x 10799 uctyar of afr in

the building. This is well below the maximum Permissible concentration
in an unrestricted environment. In no case was any jong lived radio—
active contamination found. All smears were down to background after. -
72 hours Indicating that al) the & activity was due te radon and

theron and thelr daughter products. Approximately 200 dry smears were’


Taste 4 Threshold detectors

Detector | Reaction | Product “Ty Ee ‘a References’
Mev mb

Soy
Secy 7} 3a | te 2
Hae a 1 559 Be
wehbe”. a4 tf
UR oye Ex agg f

4 adhe. 33 et
He] Bl il #
24.8 rain 9.
Sobmin | 208 35 3

§ us Selim eee
ae

Tene Mag Ne
Riots Gay hasta Be Bek ae se aoa: e alae

Appendix 3, Reaction Employed in
Neutron Production

neutron production. id
eis ace ee ee, which is given
in Mev in parentheses; at other jing energies cor-

nding values may be quite different,

formation in thi last two coluxms is qualitative
and is furnished as a rough guide.

further information see references [11 to 16}.

Appendix 4. Practical Use of

Radiation Instruments
For health protection in the vicinity of 2 neutron source,
io ave needed Whe ractation hazard from

gemma rays. A brief discussion of fon
wen here, For Sores information the reader is referred
ear eral review articles [17, 18, 19], and to the rele
erices
A. Instruments

1, Fast neutrons and relativistic neutrons (10 be to g0
Mev). As most tissue damage by fast neutrons is probably

ou

due te ionization from recoil protons, the fast-nentron dose

in rads is anally asgesged with an ionization chamber or

counter filled wit 8 hydrogen-rich gas, Fast neutrons may

be distinguished from gamma rays BF ee nate ot tre

ionisation ch chambers, one ate te nations snd and

gamma an sensitive

or baying a known residual net wendlivty (Che ity (the iter

ence in reading permits ovelaation of

and (b) use of a proportional counter he ne is Be oe

iscriminate inst et sina i pulses fae t to rays,
ent Shamivers ee ond CG CHC and CH pas

equi one CEs

chambers [181 t19 Fr

polyethylene. ¢ ene othiene
tional sat Bo sa ude ie count-rate ‘et fae
me ith 2 ve spec vat oe el tn ulses pradbed
wu cirenit in 6 PI
by heavy, les are weighted according to pulse height
and @ count results that is proportional to dose, This is
sometimes called the cuerey integra’ dosimeter.
‘This instrument is not directional, but requires somewhat
complicated electronic cirentry. ‘The eount-rate dosimeter,
however, is directional, Both asimmetars, pulse-oper-
ated ts, usually cannot be employ at sources
that produce radiation in very short burst for renuons thay
ara given above (10.7). A, scintillation-counter version of
the count rate dostuoter in which an attempt has been
made to eliminate directlonal response, has been reported

ther fast-neutron survey instruments have been widely
used, for example, t the “4 button” [28]. Caution
Such instruments do uot in general read dose, and thee:
fore knowledge of pede spectrum is required to

More detailed information about, fa fast-neutron hazards

may he obtained from instruments that measure the faat-

and from. Tnshraments that measure the
ig a distribution of the ionization due to neutron recoils,
Approximat ‘on energy distribu.

[24, 2b,
tron. mad the proton
rool raeyeon % aloud by. menauring or photographic

fee statormetion got a Re Ee diction a de dose

vei


” ze = “ 3
‘ ‘ |
.
Fab roo
ka By YasEY Raton
a ar ’ 4 By Gay PEETION
; Oy TORE DORE
we ee ‘a! ag® Re
&, onoToNs it
. Eeretnen 5
& roman nad ooye, [ Val Par
a t
y 3 re
r2
Swe iN ; “ iN =
pee =
‘ mx . 19
x AN
X x
\ iS
t 5 2 5
mel \ - Ni
af aKa iy AT.
. x . \-
\ maX
Ath ' \
1 4
so ' ot
of 6 6 8 © @ 4 6 wo wm ne ou ew oe 4 e 8 we

“ee wn Me

Ficus GA, Absorbed dose (rade) from 0.08-Mev neutron beam Fraurs 8. RBE dose (roms) from 0.08-Mev neutron beam,

54 55


Poesy

Niosf Ss
ae

his wecrmean, Vr tett Torrey cs aled
pen A ores a an ¥en any /ete ,
|" erenitots oid Mev te Aovnrt
Kawctucrr er hers Grom Qe Th” sh boe
oper —tramaein g Aacdtm. 27tudd
ormeg wad ome of rig acts

Q0- wank unt Ste Ka ction ¥lurby
Hav oF Yee Wotioneak Grrcau ff:

WHEE Bates RADI oT.

Hao Conptnnda Torvay of the Usbs Turonn oF
Stndnsda, mie one of the Rome unusual Jota In,
tha World “araguring and tratin: radius, dae an
ee © ahdwn hort Holding ebout"$2,d00-w rin of tite
corms raed ud atenent "a UF tha Mt ie yiatsnun tobe
Mumsnet At the ahd ot"the tieuzdens En the ornll trouch

ae’ BolON the tHaszory, wots than'a ell ign toll we
Rose of mdfus Bk leon Nmowd rt one tine oF
Ryothoxs The pireas sance tn shee fee eae



C., MARCH 25,

4936—PART FOUR.

(dec .h3p-%

@_wssh NeTON, _D.
4.

We ® sample of
XV" yadium from one room to ane
other the worker
gimply takes it out of the safe with
% peit of giant so built tha
giweys the hands are kept 30 inches
sway from the dangerous element.

THE SUNDAY STAR, WASHINGTON,

oe

f 4
D. CG, ALARCH?

kes bis reading by peering at the
cimen through «2 enormous “

tor” 4s the mame suggests, it
jects an enianged image on a grad-
ed screen and in such fashion
t the length and diameter can be
2 immediately. For aiways the
aratus is Kept in perfect focus.
lever --do--the Federal” Specialists
e to purchase special glass viais
wther containers in which to keep
? test radium end for this rea-
i Whey Keep most of it in the
vaimet tn which it arrives and in
y instance the container
‘ed satisfactory in ability to resist
powerful gamma radiations.

ROE made of glass, as stems to

le genera} notion. Instead. they're}

netinnm, chiefly because 2's

eS

*

“pros | geological age soaked up the

: Most?
te original containers, by the way,}

trunks of trees, which in some remote
erigine)
water contaming the radium—maybe
mulkons of years ago, These tree
trunks petrified, that is, turned into
rock, thereby permanentiy’ inclosing
thei radium content.

Dany, deautiful rock .sampies -ot}

these ancient tree trunks are to be
found sm Dr. Curtiss’ office. The Bu-
reau of Standards is particularly proud
of owning several such, hrawaish red
in shade, which strikingy show the
grain of the original woad in # beau

bas | aful, petrified form. t

Dr. Curtiss, for purpdses of com-
parison, showed samples of carnotite
and pitehblende. The Satter ss @

jovely jet black, which mo doubt ac~
counts for sts name,

“Laft them both,” he urged, “and

native Indians are employed slong
with other workmen. One dey not
long ago s certain redskin walked uy
to his boss foreman and snnoumced
he was certain there wes another large
pitchblende deposit on the shore of the
fake about 9 mile ands half from the
main-querry then being worked: °°”

“What makes you so sure?” asked
the boss.

“Because,” said the Indian, ‘st
smells the same over there as i” does
here”

‘Naturally the boss didn't take this
very seriously. However, a couple of
days later he casually walked over the
foe to the place described by the red-
skin, scraped off a layer of snow, and,
to his surprise and delight, found that
the nose tesb was correct. Sure enough,

Te warnaner= and Tl shan vou something interesting.”

Es

tn 2921 those*35 grams werg’
about $4,000,000! 4%
A possible reason for thy
radium “boom”TM might have bee
the working of the carnotite
tn Colorado had hit its
Moreover, .there . W583... -
market for the metal, for up
time there had been very Mit
refined in the entire world,
stopped within three or f
because it was found that
could never really rank
competition with pitchblen:
source of radium.
Recently the bureau expert
what is belleved to be the larg
mercial radiuin preparation ¢
‘This was « half gram of rd
——

there was an sdditi deposit. of |

—


&
e Ey MEA mens
iia By sor MEACTION,
- SS i yom moore,
Ss +
de
ms rm
at]
bey Ny La
an hy alt
ie +3 :
’ aa
*

Ria
i

ty

1
ar eer ear)

oe 4 He eb eM eR
”

Frournn 6A, Absorbed dose (rads) from 1-Mev neutron beam.

t
+
nN +
2, PmOTONS
- eK NROND*
e 1% 4 one REAbTION
i 0, Wal Nat DOSE,
we = :
‘
. aan Oa =
ad ;
'
\\
oo h
= SS,
s ‘err .
Py ey —
, * 2
Ted ry
x a =
: se
‘ AN
‘ A a
le
it 4 Kt IN
we

ot 6 6 8 Me EY Oe we mh te

Fioure 6B, RBE dose (rems) from 1-Mov weutran beam,


re

Pp A :
7 ih a
Zi ace ih 4
i He : §
id Peery - =
"d . i
Re "8
i Wy i.
a XN : i

rc

pose FT
ew © 0 @  & % 30 Be

z
Toma, a8

i

oo

{
af
:
3
‘3
j
3
i
a

:



i

Taviz b. Data on neutron production Taste 6. Data on neutron productton—Continued

‘Reaction yields
Degres of Retinal
activi
Target | eile | 8 ape, ovate : SEER | tna” corpascive
‘oF nana ; donne
(pen) Reactions . (oan) Reactions
. Mev
ORE | 080 ceremmnenn rn] 80 Coaaley.d Saree fpso |... | ome
Les | 080 ., + | 28 (eke Bex proton fF1F-. + Considerable (Bel).
Cn ee a re seen | 10-*y/proton, +| None,
(43) Reactions
2.8910" 8/ pou)
a
Sag ina
4430 a/ acon

. basayed ae

via @

(oun) Reactions (on) Besstiovs
nfyend-28,
Pi nfyaad.
(e ' uae

Bat

ie va

}axtota/eec/e | Poy. «..-
axt0¢w/eee/o. of FOR... mn

08128740. | nfyeed.2d,
OG 18 28; yet.



ws = -
Ree ss [San re Sie ek ee et mene
6 Rater oe Haein a oe
(is a Dela) ha aad f aman T “IT on protons
t — : near:
” . 1 ; Pata Y a AN H + acy near 4
%e t Op Oy WIL AER OSE
a et Lt we " NS i soot
ma +. = —t cx = < == L =S
. Ce [ote ee A — 5 SS t
ie sg snovone To ‘ hy —
4 eS es, LE Sa
ryt 5 0 toe rt a :
fort i is fueken ie 1. 1
at - ~ & = = 7 :
6 i 7 tf ‘
\ ( iw “f oa Oa . =
. t
{ - q " H
Pd { L { hee wt H hy l N 4 ‘
=F aan = = st
. aw oar on eas tessa tea
At q i n ‘ SE
. ETERS I *
Tt NY | X
wo? i I . oe M -
ee ry o €@ 4 § #¢ © HH HD mm mw mH MR 1
Fiours 8A, Absorbed dose (ruds) from 0.1-Meu neutron beam. Froore 8B. RB dose (rems) from 0.1-Mev neutron deam,
52 .



:

a

J

Si, ts just the rate of neutron releas release outside the rencto
shield (but of gous course to inside the special loop shield). ;
aftep many 63 es, fe group there is an expression 0: ;
1-67) (es) (1-e y i
sf lamenfesy8 (12) i
where 1

fmfission rate, flasion/sec (total).
ye~yleld, neutrons produced in group 1 per fission.
Ayedecay constant, sec, for group 1.

te=time eath loop particle spends in the neutron: field
per cycle,

trentime each loop particle apends on the way out

ternting ct Toop spends in the exterior
the loop, which it radiates. ° art
Toweycle time.

Radioactive Neutron Sources
The dose flose rate fromm Yadioactive neutro!
oes ae trp tn, et po et

sources. O to ae amall intensiti
thin min oeded and heugo the ‘noatienet neuiens
oiter a vary ifteant contribution to the total dose, To

this, a buildup factor is used. For Po-Be
pnd Boob wousees wide wanes or paraffin shits at tency 20

em thick, the value of this buildup

factor is
GE For th ie common situations, the Ph, permis pred i.

D (vems/br) SBI (a8)
where
Sesource strength (neutrons/sec).

ce from source to for which the dose
rate is to be calculat

B-mbuildup factor, 5.
. gendose per unit flax for neutrons of the source
energy (rems/hr per neutron emt /aee) :
Hyemacroscopl removal cross section for the
and obtained from table 8
ox cal using nine-tenths of. the

not included thereon. .
T==shield thickness (em).

Accelerators .
_ Accelerators which yield neutrons can be shielded ee

the removal .
Fone pe Gaereies wp te 80 arco santos of the tonal
cross section,

. Appendix 7, Neutron Protection Near
High-Energy Blectron Accelerators

Because there are many ep ot high-ens
aceelerators and because ik installations vary
practicable to give general asia for ete te
amich would be valid for all cases. However,
factors.may be pointed out that govern the neutron shicld-
ing problem. ese factors are in the energy of the
photons and (2) ‘the the type of shiek shi material Used The The
primary sources of jg onerpy crectee
accelerator are the machine itealf and ‘where the
beam 1 surikes th the wail (40. the
en eeron, production. ‘0 berate a neutron from. nue
Shei coe fara inthe madleus of the order
ent © le m e
. ‘“Mtey, mo Mev). Therefore electron
accelerators of energy sty about id ‘eee will have yey
smail foal or no me neutron. backgrounds, Common
threshold and information on neutron jelda fot far
are 8 are given, in ee ole 56 of
of energies mut
eee oda cee Sey
i) incident on may he a »
BI Fam bAi,, where *evtren

where Yeu the number of .
the total incident photon = Ge,
times photon energi

anes f pliotons les) in
a Y v: approximately the square Toot of ihe
wrote nemo. above relation say’ therefore be 76

written Y.-0.044\/Z' Wo. The photons have energies of
onder of £0 Mey, ‘he neutrons are produced sl wide
distribution in energy, He average: or lead about 2
to 8 Mev, and for carbon

about & Mev [40]. As photon
85


24. Accelerators

24.1, Tt dose rates in excess of 2.6 mrama/br may be
neared n acgessble rovions outside the shiclding, or in
the absence of shielding at any accessible location, auch
yenioos stall he nea aiek ith in sone Sak hdate

24.2, accessible region inside tide eieing
where AM rate in excess inal "arents/te exists shall
be segregated

marked barriers that, in uninten-

‘access. Such areas shall be Foon with clear’ visual

indication tion whether the
24.8. If the installat

motion of de similar impediments, provisions

shielding, it shall be the duty of the radiation
at a constant check is made that pertons

loses in excess of the permissible
sections 21-1, 21.2). “Persons” incindes 0) , experi
menters, visitors, and individuals eqnpla in
or other duties not directly’ with machine .
tion. Such checks shall include a daily assessment of ‘the
operations of the accelerator.

2%, Reactors

25.1, On_ start! for the
éfficency of the Se tren fr he fe th tig the

86

i
A

ccessible region should be surveyed for radiatio
oe wiate adjustments should be made in the tion a
ee ee iit dg bosaible forint Jeske to 0 develop,

should,
changes have een made in the shfeld or 1 Jenene.

25.3, Because on of 6 senator radia nn eves te

Fe eae eat al pereounaln the ninity Of the
nel in
reactor ave made aware that startup is

planned, Par!
ig et of Une fat yo an nr tor with
period 1G is ertod,
oe, Tn Tha let of Sh recor, cnt nous. viewal

ication shal i be eroded to inform mnnel whether
the reactor i Pon

is in
26.5. petares the changes of .
tape Ses shall include seinaltton ois the ‘tadia-
Fran Qtaeer oval of a shielding blk, or first

tating of a ben tap paced bend Bombe shut,
vba be performed $0 angers the existing Tadia”

nes 25.7, If done zeta in caters ct 2.6 mrems/hr can be
in accessible locations, such ch, Feglons sha shail be
gabe tiny
2. rr te al Tegion where a dose in excess of
be segregated

wee

by marked barriers
ae Fe near ere cece an acedent Yt may be
evacuate the bu and probal

also th W outside, a plan shall be devised fc
© are & levi lot
evacuation, Responsible le persons be designated
avallgble at all thes for its exeontiog. AN pargorel norsa-
ally in the environs shall be made aware of the plan.

26. Surveys at Accelerators and Reactors

26.1, During tune-up and initial operations, surve
of both the gamma. a1 and hal ntzadinen don ale
accessible locations ontalde the shielding shall be performed
ag soon ag radiation imtensities in excess of 2.5 mrems/hr
are likely to be produced.

26.2. Prior to routine operation, every accelerator or xe-
actor shall be surveyed, Such surveys shall be repeated
Whenever berating surveyed. Se are, shane in such 8

neutron or gamma may change, In
absence of any such changes, surveys shall be made at

87



oF PES — —ew
EP rae
. Pe

& hal
8 iy MAE RRONS
by ny MEACTION
1 Ey YOTAL SAD 0088
j

147]

5)

Lh

Amal aN

| \
we L. .
o f£ 4 £€ @ @© B@ 4 HH & fo 8h tH Oe HO

Ficvsn 1iA. Absorbed dose (rads) from 0.0001-Mev neutron bean,

58

we
ae $c =
ol she B hencren
==
3) y art t
ims:
Fy pag! is
1. u rt
ote — i
A) ho i
LY ; ‘f | :
ot TT |
oe i =|
: AN
MTT :

oe « 6 © «& GW Bw % 82 Re Oh 30 ¥e

Friours 118. RBI dosa' Crema) from 0.0001-Mev neutron beam.

69



w
ad ——
7
*
%
: Paeit
ra
Wetle 4 A
oe a
ES -
4 Lp POSTONG
hy Ey HEAVE RTO,
‘ q By eny REACTION
&, orm maoeae,
1. J
. +
S
\
5
- \ a
. i
cy ¥
2 i > -
1}
= a it

o a 4 4 8 0 8 & w @ 20 we tt wm 2
o

Fidurn 104, Absorbed dose (rads) from 0.005-Mev newbron beam,

86

a
1 - t
ry By Porn
and! HOA we
bad feet Ot hey neato 3
aes 2 ToFAL RAK ONE
, =
is KMSTO i
y

eT

nw
_

-\
ett NV
o tt ¢ © @ © @ © ft & 20 @ te 26 oe wD OM

=

Frovxk 10B. RBE dose (rema) from 0.006-Mev newtron beam.



Copies to:

Hatnke
Chaliman Radiation ‘safety Coumittes

Philip Smith

GSA Bulidings Manager

Room 410, Suitding &

Aabed Connecticut Avenus, H.W.
fashington, D. €, 20003 - -

Harshall Little

Chief, Radiologica) Health Division
Depsrtment of Public Health
Goyerzment of the District of Columbia
80! Horth Capitol Street

Washington, D. C. 20002

dohn ¥. Brink

thie?, Sureau of Public Health EngIneering

Departeent of Public Health
Government of the Bistrict of Colunbdta
Washington, D. €, 26063

Clavd= Rewe
Health Physics Section

Files (HP)



stant Ball on Tests Weather Device” |

Two Buréou of Standards scientists are” LL. Stockmann, who works with Dr. Curtiss,

teaking ready here for the test of another Tadjo- ~ is test ‘the radiometeorograph here with a

« eeteorograph, @ device attached to parachute wave meter before attaching it tothe parachute

fa, yatioon and sent into the skies to radio and the balloon. The imfiated dag usually

i nals giving the pressure, temperature - breaks several hours after it soars away from
i humidity of the upper air. Dr. L. V. Astin the roof of the West Building on the Bureau of,
the bureau’s electrical division (left) and Dr. Standards grounds. The instrument is then
Curtiss, head of the radium division, are parachuted to the ground. The bureau often

|. tying the mouth of a giant balloon, preparatory gets thém dack. The radiometeorograph con~ -
. ginning the test. The dalioon carries the tains two radio tubes, a-miniature ary cell’ bat-
” ment as high as 50,000 or 60,900 teet—9 tery and devices which record and send the
‘Wiles high. The test was conducted for the weather signals which, in turn, are recorded on.
- . @ chronograph in Dr. Astin’s roof radio room.

, . ” -LStar Stow Photos. H

ay on



doc AY

Buyret! Brow ny
age 24


wt wr
‘ +
laaet mE ‘ ies t
e SS peers Ld ee Der PRETONS,
: 2 oan nate {% oy Minne recone
wo hohe ceyrewhon wil IN 2, orkcaac oat, ‘
- Tota. ran ane x = '
‘ PERO +} ‘ 1 ~
eT mi t ws,
aa % BS !
’ eae = 3 * “4 Si
on Lote in i aed de in \
(=== a ; RRS

; 9 oo ; TN
- MI cle : - INERSE

Cnn eer a rere reer ae eercwerrernaed . Ce a ee a
t o

Fraogm 7A. Absorbed dose (rads)‘ from 9.6-Mev neutron beam.

Brours 7B. REE doce (rems) from 0.5-Mev noubron beam.

50 51

|
|


=

Taste 7. The U2 fission spectrum of prompt neutrons*
Ji ieae tt the trgstion of neutrons of aniegy & to BEE from thermal

a ey
z
8 xen Sjnener S roman
Mew Mot :
04 0.9098 0.018 0.9860
2 200 ‘31 ‘ase
4 ty # Ea
$ BS BE in
A 8521 1669,
i|/® | @ | #
K hey $708 vant
x0 wa 3082 00%s
M4 369 pase 818
1 a EY “aut
8 8 Fa
18 Bh 4068 3017
18 tt 2 4869
po) EH #
0 x 18 3
a i Re Bu
42 07478 3014 1986
06981, on 0808
53 “ RH 9697
5.5 af 684 0876
8.0 01016 TET (361
a5 91881 . 0179
to sarex10-+ aa “oust
a sass gag ¥
Hy rote band our
9960 0040
20 2.078
9%. pest) pti ane
Fe ian ae Ess
38 1994 (9908 BA78
BE | fpr ria Has
16.0 5 19 24s

* Cal from the formula of B. E. Watt, Reg. 8%, 1087. A162). See
also J. Ewa Feat ‘from water Boiler, Los
Retentiho Laborettny, CASS CARCD sore) "t 1851).

counting all neutrons as if were in the energy
group, This simplifies the lation, is reasonably aceu-
rate, and is conservative for shields that contain reasonable
quantities of moderating material, Examples of such ma-

is are the water-bearing concretes such as ordiary
con barytes concrete, magnesium oxychloride conerete,
end len masonite, moist earths, etc. Other materials
8 .

‘

wo

0.8, aN +

oe

N

ou
= 9.0)
t ——e
4
TR oe

[X~ xebUCROBCORE EHOW CROSS RECTION

' z 5 i RO 90100 ROD B00 «1000
A, ATOMIE WEIGHT

“Fuuure 17. Pieston neutron attenuation cooffotente,

do by ‘) verens
ee ba) Temowad sross sections divide density)

(large atomic weight, 4>16),
such as iron, | ete. ‘be counted as well, provided
they are followed with ‘noderating material on the outside?

emovab Crass Sections: Removal cross

val
cross sections to be used in calculati
fast neutrons. The microscopic removal cross section (
three-quarters f the t

is ly of total cross section at
Mev, an e n being hydrogen, for which the fraction
is somewha' .
The macroscopic removal cross section is given by
ee (6)
* Cantion: nonmodersting mat axe relatively transparent to lows
sor cis Be Sere ach lie Sele a

7


7

Befors Decontasinat ion

Ko contamination >2500 c/m @ was detected In Rooms 500, 5,
$05, 508, 509, 510, 512, 516, 517, and the Filter Rooa,

Room 502
$30,000 ¢/m on wood shelving
< 2,000 c/m tedge over door
= 5,000 c/m concrete floor
Room 503

312,000 ¢/m wood shelving
s 1,500 c/m ledge over door

< 1,800 ¢/m wood frame for room partition

< 2,500 c/m floor
Room 50%

‘

"S &,000 ¢/m spots on wood shelving

1,500 ¢/m floor’
Room 507

< 20,090 c/m stee? beams

250,000 c/m concrete ceiling by skylight
§,000+150,000 c/m brick section of left wall
>500,000 c/m spots on lower section left brick wall

5-20 mr/hr contact spots on concrete celbing
s 40 mr/hr contact 4 spots on floor Sn room

Room 518

S_36,000 c/m.wood. shelving
< 500 c/m walls

s 1,500 c/m ledge over door
S 7,500 c/m floor

Room 519
< 22,000 c/m wood shelving
= 500 c/m walls
S 3,000 c/m floor
Room 520
s 48,000 c/m wood shelving

< 28,000 c/m ledge over door
s 8,800 c/m Floor

< 7,500 c/m wood frame between rooms


9.

10.

ih,

12,

Room 521

< 3,500 c/a spots on wood shelving
Ss $2,000 c/m Floor

Room 522

$120,000 ¢/m Inside ventilation duct
$200,009 c/m Floor eround 2ir duct

s 40,000 ¢/m other Floor areca

= 35,000 c/m ledge over coor

= 60,000 c/m section wal) behind air duct
S 75,000 ¢/m wood shelving

s 12,000 wood frame for room partition

Steps leading to roof
S 70,000 c/m

‘

Roof

$ 10,000 c/m gravel on roof near skylight
$350,000 c/m fan vent

150,000 c/m skylight

>500,000 c/m fan

< 5 mr/hr contact Fan vent and skylight
< 15 mr/hr contact fan



>

Scientists Find Device to Protect Radilim ‘Workers From DMh-

Remote Laboratory Is Used
for Research Activitles

With Valuable Metal. -

By James N. Miller.

WN A remote Washington laboratory
‘ the other day two solentists, 2)
man snd a woman, unwrapped a
“A enormous crate. Armed with!
hammers, they worked with feverish,
haste, so that within half an how
thelr job was done, ~ '

‘Whereuporygino gentiernns turned

ine dB nung

ad something worth white here.”

‘And 50 they had. ‘The crate, which
they now examined with unconcealed
pride, contained thelr awn “brain
child,” a truly marvelous new device,
the only one of its kind in the world,
which enables research workers to
test redium, the most dangecous metal
known, without the slightest danger of
thelr being unduly exposed to the
death-dealing gamma rays,

‘The two selentists, Dr, L. F, Curtiss:
and Constance L. Torrey of the United
States Bureau of Standards, after a
year's research, developed the idea
for the revolutionary machine taward
the close of 1935 and detailed & New
York manufacturer to bulld the actual
apparatus, .

‘Most of the commercial radium prep-
aratlons now being leated for “purity,”
with the ald of the new device, and
others alsa daveloped within recent
months, ate the so-called “radium
needles” and tubes, widely used in
therapeutle work by the medical pro-
fesston, They may contain as little

qas one, or a8 high og 100, milligrams
tof radium, and otten are only an
eigth of an inch ‘sng aud one-thirty~

second of an ior 1 diameter.
waadicat agenuy wilt

PRFAUE »
buy a & a ao of these tiny
“needles.” Th., May have aboub the
sams siza and appearance, aad it ts
necessary to have an identifying num~
her cut on each Individual needle, s0
| they can be told apart, In such case
the medical agency will std the:
“needles to the Bureau of Standards,
whereupon this procedure will be fol

|

5 feet away from the “needle,”
manipulates a “long-distance” stylus.
which carves the number, If the
stylus moves a hatt ich, the num:
her will be only one-one-hundredth”
of att Sich fn height. 1
‘The hureass scientists have also per-!
fected @ projection machine for read-*
tng these numbers from a sate dis-
tance of 6 feet away from the test
specimen, ‘The average therapeutic
worker can use a magnifying glars for.
this purpose without personal danger.
because he might have occasion to
identify the numbers on his radium
needies only two or three tmes a year.
whereas many times in a single day
the Federal experts must do so,
Since always, by means of these pro:
tective devices and numerous othe
the bureau sclentists are able to main-
tain & distance of 10 unches to 5 feet

towed:

away from the dangerous element
thaw ara atndving. there 13 very lide

Engtaving microscopic numbers on a radium prepa-
ration for identification by medical agencies. The
operator (B. W. Brown) sitting in perfect safety, 5 feet
from the radium, manipulates a stylus, the only machine
of its kind in the world, which has just been developed by
Bureau of Standards scientists after years of research,

Jas Sandied about 10 Gmes as much
fradmmh as vit the lute Mme, Curte,
who discovered the preclous element.
Yust of ali, Dr, Curtlss explains cer
tain elementary but highly interesting
{ets about the metat, which ir about

sclentista are givert # thor-
ough physica examnation, x

GuAL, we now make an imaginary
visit to the bureau's radium test
ing laboratories and examine for our.
selves some of the most interesting of
the new ;saley gadgets? All right,
let's go,
The latioratories are on the third
oor of tife enst biniding fn the heart
of the exclusive residence section of
upper Connecticut avenue, You enter
room 217, & sniall offtee, and are privle
‘eyed to ‘meet the Internationally

cally the,

aad sells on the commercial market for
$10,000 a gram.

“How big is a gram? About the size
cof a tiny tube less than an eighth of
an uteh square,

“Radium $s a fiercely active sub-
since, which emits three kinds of
faxs, siphe rays, beta rays and gamma

$9,000 times worth its weight in gold}

speeds of tH» order of 10,000 miles B
second, "

“Beta rays “are negative electrons,
expelled at much higher speeds closely
approaching the \veleelty of light
186,000 miles a sedand, Becouse they
are lighter than sinha nartictes, they
can penetrate material through which
alpha raya cannot pass,

“Gemma ravs are similar In nature
to ouchnary fight, but hive & wave
fength very much shorter and conse-
quently ave more penetra.ing. As @
striking example from our owns test
program, one or two mulligrams of
fairly pure radium. ‘actosed In @
jeaden tube, with walls '4-mnch thick,
are able to discharge rapidly a gold
feat electroscope held arywhere near it,

“Radium preparatio 1s are also self+
luminous and possess ¢.0 extraordinary
naar ae bringing about chemical

which ¢ a positive charge. ‘They
ate expelled} from the radium atoms at

ey 2°P


ag aS

=a ee

ie

. eo @¢ «a 6 oe ee

.

Figure 8B. RBE dose (rome) from 7.5-Mov neutron beam.

as rr a ae
T Tt. i

ium Ld 4d lo,
7 rr te
{ pai Ta $
“ig ue Ht
Ree ig ., et
psa) a fa
' ams Hl tee 3
1 Rg

ede

t t AL LL
ica de CY



feo ;

4 . Pabddic Heal th -
domes I. Porter, Chie?
Office oF Cosign a Engineering
e H2pavtzont of Buildings & Grounds .
oi +34
Yavsnell S$. Little, Chio? fpriT 38, 1958
Redioegical Ulealth Civision

Final Report of Radiation Protection Evaluation of Hashington
echnical institute Buildings, Formeriy Occupied by NES.

fn the absence of Hr. John ¥. Brink, Chet, Bursey of Pub}ie learn
Engincering of this Department, 1 was asked to report to you cur Tiadinss .
"and YSctkrendatians with respect to the radioactive contamination of the

There gs attached a cony of a Jatter fran Mr, Brink, (Attectnent VW
which briofly eutlings the prodien initially discussed with you in Fodrunry,
Following the rst clscussiens at this problem with Or. Sciwebet, Caria?
Realth Paysics Section of the fistional Bureau Of Stentards, cur staf? me
aa exhaustive survey of 217 buildings formerly oceupled-by 3S and sehe-u}
for yelexse to your Dopertment. Cur Findings were reported to Dr. Soin
who arrenged for coconteainaticn of the ecititics, |
: . i :

“There 2s- enclosed a cony of the Final yeport of Dr. Schwabel foticving

the coxpietion of the dscontamination, (Attachment 2), Following these
® Cleaning czerations by Or. Schwetel's Stet,

v3 OF cur Division mada

a finsl resvslustion of a2} areas. We are jn substantial .agreeman= with the -
Conclusions of Br. Scimebel, hovever there resiain three arens oF concern,

ai? located ta Building £2:

“1. Roem 592

Although we co not fee? that a radiation hazard exists in this
roca at the present tine, radiation measurements show that an unknowm quantity
of radiun is still present In cracks, pits, holes, and painted cinderdice%,
his material is lorg2iy fixed contoninatian and is no hoxard-as-lorg as et ~
repains fixed. wnfortunately,-however, tha formal aging Rrocesses corsled
peith-the possiSility o? unusual use or waar and teer may uncover this pidion
\creating @ hazardous, or at Teast, an alaraing condition. For this restos
and the fact thet this snace dses not appear to be vory useful, we reccocend
Rant the door bricked over and the skylight sealed to pormanentiy off-
Hinwte the av, iity of this roca. .



es e

‘These curves were obtained va
tories in an unbiased manner a vera sing Ge abeorbed
dose delivered from a sample of such Tae mini-

:
J
a
eel
a
i
ghg8e

actions considered were elastic scattering, the (n,
nara tion with nite en, and the a) Teagtion oes

Os

Lechcclat ah lng tn ot aol.
a
a
Hil
2
B.
$e
3

been,
y y Livingston on Bethe [8] and for the ba em
ts of terest ‘here has been a)

T

an
WEUTRON ENERGY, Mew

data were computed
duced i lglg date yrs compu

RB ction. " particle

the, big ne dose shivered by a ee ile of given

and ths biol for cach particles pee’
of tal Melos ihe

—

ytays produced were o fallowed algo

Ot

Frauen 18. . Effect of buildup on neutron dose.
. Ba gag
+
°
3
E
82.
Hf
a
at

or Or sampling method, and i aecrad Sey meee, (RBH OBE dose

wl apie one ae he eal

TUT

|
00s

tes the general trend. In some

"FIRST COLLISION” ASSORGED DOSE
"FRAT COLLISION” RAE OCSE

cases where the penetration was small, few or no events
and the curves were not con-

MAXTMOM REE DOSE {3O—cm SLAB?

SALIMUM ABSORBED DOSE (30-cm SLAS?

y

oceurred in some intervals
a tinued wiiete, ‘the data did not seam sienificant. 14
gives the RBH BRE dese/absorbed

Ki

2
of queray and 4 The fi Pete dose of OB Tan
in 49 hours or Te eet a Ree con pate
/ and is shown in figure 18. The ratios of maximum dose
for the 80-cm slab to first collision dose for both absorbed

002

N
Shmeol i LS

&
s
4

a 7 a 3 4 dose and for RBE dose are shown in 15. The low
puye ° values at 1 Mev and 0.44 Mev are not entirely due to
statistical fluctuations but are largely due to the resonance

. in the oxygen cross-section curve, As a check on

65


counter or pulse-counting fon chamber, if one can be ‘sure
of a one-to-one correspondence between disintegrations
and counts. The counting rate corresponding to complete
detection of the disintegrations in ionization has.
been obtained with an accuracy of about 2 percent. ‘To this
exter musi be ised the Uunertat in Rosen, ross
5 ao the a ou same

that of the standard pile lux, Fie ‘absolute disinta ‘ on
autvon fity to beter than 6 pescant, aldaough the accuresy
ne in accor

could definitely be increased. ° ney

The simplest method of relative flux measurement is by
Tee ccna fox hace, is a good tester for Tae
ol, mM or wa ma
dive determination of high, flux becange it hag a conve t
half life (2,6 hours), and 9, cross section (12 b) that is
small enot so that excessively thin foils are not neves-

‘by
its presence nor any self-protection of foil itvelf. The
activation of a thin foil does not end on the
of neutron travel through the foil. is shown in the

ax is just the neutron

activation formula above, where fh
density g gaultiplied by the velocity, with no directional effects
vi

B. Intermediate Neutrons

There has beou no extensive work on flux meastrements
for intermediate neutrons, primarily because there has

neutrons.
moderation, and the strong “self-protection” that reduces
interaction in bulk material, intermediate neutrons are
rovch Jess important than fast or thermal nentrons.

68

C. Fast and Relativistic Neutrons

Because fast neutrons represent such a wide energy
range, over which detector response varies widely, accurate
flux measurement is extremely difficult. For these neutrons
the simplest method of flux measurement is by comparison
with the fux emitted by a standard neutron source, usually
a Ra-Be source.” For thi comparison the standard source

type

affected greatly by any energy difference between the un-
jmown and the standard flux. Unfortunately, most fast
neutron detectors are not independent, The long
counier is specifically designed flux comparison, how-
ever, and can be used in energy region 0. to 8 Mev,
in which its sensitivity varies 5 percent.

Fast neutrons, in contrast to of lower energy, cat
be detected by means of the recoil protons they produce,
and in these protons can. be used for flax measure-
ment. tt is difficult, however, to measure the recoil protons
quantitatively, for example, in au ionization chamber, and
thus obtain the absolute flux incident on the recoil counter,
In practice an accuracy of about 10 percent can be reached

axe very difficult.
Activation. of foils of known cross section, which is so
useful for thermal flax measurement, is rauch more difficult
to apply to fast neutrons, pr! because of the wide
energy range of fast neutrons, In mnaterial, moderation
produces ap energy spread, and a foil that has a cross

section varying rapidly with f
interpretable Sa ee of reactions as fap),
Re), (0,20), and “ can give approximate informal

on the fizx value in different energy regions, depending on
the reaction, thresholds. Table 4 gives occasionally emn-
ployed reactions and their thresholds.

the neutron flux from « stendard source or in micamtring

‘wworee "fons sounters ft tust
Emm ae Sectiooe arom soutere is often anlwokropts.


i it.

*

vo ewe we

Fiaves 2A, Absorbed dose (rads) from 10-Mev neutron beam.

40

at a hieee PE

oe bpp. Pop nf
4 aera

f ime a
Se

Lib idi tr tpt

oO ere

Froumn 8B. RBE doss (rome) from 10-Sov nautron decry

a



SIU A tt te, eoeneeetmes oe

222

Alr Sampjos for fa

Date Taken Before Clean-Up During £)ean-Up After Chaan-p

1, Outdoor ~ East Bldg. 223-68 1,2 x 197!0
© 2628-68 AH. 1.0 x 1o7}0
2~28-68 PM 4,3 x 107)0 alt
3-19-68 8.3 x tov 8.3 x 10
2, Room 518 and $45 2-16-68 2.0 x 3078 . 10
‘ : 2-27-68 . . 1.5 x 107
3. Room 522 2-16-68 2,3 x 107!9 “10
2-27-68 1.5 x to
3-19-68 1.6 x 10710
4. Room 07 9416-68 3.6 x 197!0
2-19-68 3.2 x 10710 io
2-23-68 2.2 x 1015
2-23-68 : “10 1,5 x 10
2-23- 4.3 x 40
2-27-68. Room sealedovernight - no vent} tation 6,2 x 078
3-19-68 4) x 10
5. Room 48 © 2-23-68 3B x p70 10
2-23-68 74 x 10 -t0
2-27-68 . 1,6 x 107!
3-19-68 1.5 x 10
6. Room 403 2428-68 2.8 x 19° !0 os , “10
3-19-68 2.4 x 10
7. Room 316A 2-27-68 3.6 x 107!0 “10
° 319-68 -10- 2.5 « 10
8. Room 316 2-27-68 3.3 x $0 : “10
a _ 3-19-68 2.5 x 10
9. Rooin 317 2-28-68 “3.6 x y07!0



energy increases, the neutron protection problem becorites
more serious, presumably because of a high-energy tail to to
the neutron Gistripution. & the mean free rata for fast i
neutrons wger (approximately as
ee neutron, gnetay increases, the the choles of of hig ay,

ery high en electron accelerat
fal th fa-ton crete or other hydrogen-contain-

uy ‘om or other
ing materials are desirable for neutron shieldi mg. However,
many electron accelerators are shielded with lead, fre-
quently as an integral part of the machine itself, The lead
seta both as a sizong source of Paotone! otoneutrons and as a
Pomriae the neutron ‘production near the high enorgy ek

a me hue near
tron h aecelerater has Veen established od. (remerabering hat

that
trons mA} duced i the hield the
nee . be produ in a fed uel ‘he nexteon

the
methods ined in a) pe fetermined
References
L ecommmonaions of Jotemattonal 2 Commisni dio-
ue be og ee Soe eae also Report soe Rea
iso
), NBS 62 i v0

{21 Lewla BR NPs Bandhon Henyaan Lace and Joneph | G. Hoffa:
‘The acute Fedlation syndrome — 2 stad; yf nine cases
aaaaer of the problem, Ann. Internal 86, 2, 279-810

(3) BR. J, Hesterlik and L. D, Marinelli, Physical dosimetry and
t clinical observations on four human beings involved fo an

gecldental critical assem) Proc. International
Conference on Peaceful en at af Atenas Energy, p. 25-84
* (Geneva, 1965),

‘4] A, K, Guskova and G. D. Balsogolov SR), Two
M4] ponte ite madietion disease in man, Pub internet onal, get

Peaceful Uses of Atomis Energy, p.
fer 1968). eee foro ,

T, Jz. Radiation cataract, AMA Arch, Ophth,
i wet ai ts. men
[6] P. H, Abelson and P. , Cyclotron-induced vadiation

cataracts, Solonce il; 668 {i840)"

17] NBS Teck. News Bul, 41, 17 (1987); Radiology 68, 260 (1067).
ML 8, Livingston and HL A. Bethe, Nucl experi.

Be) Metal Hoe Mont Bist: 8 BANS aS

9 and 3, Neufeld, On the passage of hea

FOTW ian eens arae Reetiok hearse naa Pe

86

wate Ge Oe

{10}
(11
12]

[18]

[14]

[35]
{36]

liv] B.

018)
19]

{20}
{2)

(22] N.
(232

{24]
28)

W.S. Snyder, Calculations for maximum permissible
to thermal’ neu trons, Nucleonics 6, No. 2, 46-50 26-60 (1850),

F. Afzenborg and Lauran levels of light nucled,
Rave Mek, Phys 2h BBL DBE) Yet Of Tigh

HL. Anderson, Neutrons from alpha emitters,
Research Counce’

alpl
nh A aH
ara Ok coi lear Science Beries, Pr mary

B. T, Feld, The Oey, dt Sens. rimental giclear
ES5¥ Vol. IX (Sohn Sone, Inc, New York,

4,0. 0. Fanson, 2 R. F, Taschek, and J. H, Williams, Monoergic
sei Revs, Mod.
ia tron ivan charged particle reactions, 8 Phys.

H, T, Richards, R. V, Smith, and C, P. Browne, Proton-neutron
reactions and thresholds, Phys. Rev, 80, ou (1960).

A. Wattenberg, Photonsutron s National Research
ea Nuclear Sclence Series, Preliminary Report Na. 6

(1949;

Hy Morey» Nacleonies 10, No.4, 1¢ (1982) and No, 5,14
(3962); 3. W. U. 8. Atomic Energy Com

re igs CLASSY.

HH, Rossi and G. Failla, in Glasser, Medical phyatee, vol. EE,
'p. 608 (Year Book Publishers, Chicago, Ml,, 1060).

L a catgeinelt in Anza Anya} eviews of Nuclear Science, vol. Iii
Academic

G6. Hurst, Brit, x medial, 27, 858 (1984).
G. 8. Hurst, R. H. Ritchie, and H. N. Wilson, Rev. Sel. Instr.
22, 981 (1951), .

|. Skjoldebrand, J. Nuclear Energy 1, 299 (1985).

3. S, Handjoser and W. A. Higinbotham, Rev. Sol, Instr. 25,
98 (1954).

B. L. Cohen, Nucleonics 8, No, 2, 29 (1961).

E. Tochilin, 8. W, Ross, B. W. Shumway, G, D. Kohler, and
H. Golden, ‘Reilation Recesrshs S488 GOI).

(26] A. C. Upton, B. P. G. S, Hurst, and W. A. Mills, Radi.
al

{27)
[28]
[201
{30}

re)
32)
188]
134]

tion Research 4, 117 (1066).
L. Rosen, Nucleonfes 11, Nos. 7, 82 (1958); No. 8, 38 (2983),
R. G, Cochran and K, M. Henry, Rev. Sai. Instr. 26, 757 (1955),
H. H. Rossi and W. Rosenzweig, Radiology 64, 404 (1955).

3. Bi Roost and W. Rosenzweig, Radiation Research 2, 417

J. Boag, Radiation Research 1, $28 (1984).
A. 0. Hanson and J. L, MoKtbben, Phys. Rev. 72, 678 (1947).
R. A. Nobles et al., Rev. Sci, Instr, 26, 834 (1964).

“uh Angletan, WU. 8, Atomic Energy Commission Report

87


Teast once a year. Tn installations where Mquid shields are
‘shall be performed

employed, 8 survey be ‘at least once every
6 mouths.

sya pro stay ch Wort sar at is
e

EL When pergtel ate expend to dos sain

. When are @ eX
cosa of 80 mirems/hr, continuous personal monitoring shal)
be performed ler rele atimntes ‘of the dope roeelved
can be obtained by other nets.

22, Health

87.1. Prior to beginning of employment, each person
worbig novo than foeelpally in trea are

‘be done once & year, wnless more frequent examinations are
indleated by seadings of monitoring Tistrements.

2%. Overexposure

23.1, in exceas af the it
shal races (he Incedate stanton the tation pros
management. Corrective measures

4

88

extent of the present injury, and the probable outcome, A
competent panel, including a ician familiar with radia
tion risk and injury, a protection
offiear, and a responsible admin! se, shall review the
medica} fzdings and decide on the advisability of renewed.
examinations, shall investigate the reasons for the
overaxposttra and undertake al] reasonable efforts to pre-
vent repetition of overexposures.

Appendix 1, Depth Dase
depth doses resulting

q,
he @
where 6 and L are parameters charactoristic of the source
and the size of the Hasue equicalent phantom, as follows:
‘Bouros Rhentenn, » L Baterenteat
-
Eo] seein] Le ts &
PoBo—————] Smal_—__—| 138 | 1188

BTR AE kT ASS Ball, On 10

‘Theoretical depth dose curves have heen computed by

Suyder oie are of pevizers euengles. 7 ue furves shown

a am Vee

itera ae aro

monomer; et nor
mal fo oue Zace of the alah, *


UNITED STATES GOVERNMENT . U.S. DEPARTMENT OF COMMERCE
NATIONAL BUREAU OF STANDAADS

lemorandum

Mr, Robert S$. Walleigh

Assocjated Director Administration DATE: March 22, 1968
. Through: Or. Wayne W. Meinke . .
Chatrman, Radiation Safety Comal ttee In teply refer so: 500.02

"ROM: Abraham Schwebe)
Chief, Health Physics Section

UBJECT: Release -of, bulldings at Van Mess Street after decontamination .

. From the early 1920's cill 1952, the Radioactivity Laboratory was
located in the East Building (Building #2). Al) radium samples- used
in this country for medical purposes during this period were measured
In this building.’ Since the technology of sealing radioactive sources
was then in the process of development, theré were numerous leaking
sources recelved for analysis. As a result, a number of rooms in the
East Bullding became contaminated with radium-225, When the radium
laboratory was moved to Its new quarters In a speclally constructed
Isberatory In 1952, a1) the wood benches, floors and other equipment”
In these rooms were removed as radioactive, waste and new Floors and
baseboards were Installed Ia a number of rooms. Since 1952 these rooms
were used as non-radioactive laboratories and offices. At this thne,
@ it should be potnted out, there were no health physicists at the
“Bureau and this work of decontamination was supervised by the physicists
“ In charge of the radium laboratory, .

When the move was made to Gaithersburg, it was recalled that the attic

In the East Bullding had been used as a laboratory end for storage areas.

Room 507 had been cleaned, painted and new floors put down sometime .
+ after 1952.. The walls, though they showed no removable contamination,

were found to be radioactive in spots to the extent of al mr/hr..

There were a number of spots on the floor which gave y-ray readings

Of <) mrfhr. The-doors to this room were sealed and "Caution ~ . .

Radioactive Matertai" (CRM) signs placed on the door. fn rooms 518 | .

and 519 numerous samples of radioluminescent paint were found as was a

large amount of conteminated equipment which had been stored there

years ago. AI} this material was removed as radioactive waste. A

number of dry smears were made throughout the attic but no removable

contemination was found, No attempt was made to decontaminate 2)

rooms 518, 519 or 520 but the doors were sealed with CRM tape and

CRM signs were posted. :



After decontamination ao gomaa~ray readings could be detected anywhere
with the exception of Room 507. Ia Room 507 there was a t area on one
wall reading 1.5 mr/hr and over an area oF approximately 5 feet readings
of approximately 0.20.5 mr/ar can be found, Stace this is on bearing
walls no attempt was made to decontaminate ‘by removal of brick, The
areas were painted with 2 coats of. Jead paint. On the Opening for the
skylight the concrete reads up to 0.2 mr/hr in several smal} areas .
(approximately 10 in®). The overall] readings In-the room are approx
Imately equal to normal background of about 0,01 ac/hr. Two hundred
dry smears taken tn the various rooms gave counts of tess than 10 &
counts/minute. . .
Since the acceptable limits set were 2500 fixed a counts maximum and
1000 average and 0.2 mr/hr maximum gamma and 0.05 mr/hr average gama
readings, -we have more than met the standards we set.

. :


Dealing Rays

’

Ingenious Method Employed
to Keep Element Beyond
Possible Danger.

extremely marked physiological ef-
fects, destroying Ussues when the
radiations act upon them too long or
too intensively. Fortunately for med-
feal sclence, the radiations also destroy
disease cells of certain types as well
es normal tissue. This Js notably the
case In cancers, other malignan‘
tumors and, i> certain non-maly +
tumors.”
WHAT i purity fn radium, and how
does ;it concera the bureau
scientists?” Bear in mind, first of all

certificate, issued by the Buresu of
Standards, stating the precise amount
of radiation it gives off, Oddly enough,
the certificate never states whether
or not there sctually 18 any radium

occurring with the radium in nature.
|. Phe-official judgment-of-the burest
‘Selentists, after almost countless tests
of sample radium 1p thelr laboratories,
fs this: Ordinarily, if @ radium salt 15
99 per cent radium vromide or chio~
tide, it 1s considered of a fair degree
of purity, Jt is = safe generalization,
Dr. Curtiss says, that practicslly

the so-called radium on the American
commercial market is around 99 pes

other elements.

Strictly speaking, then, what the
Bureau of Standards experts are called
upon to do daily, ss their most ims
~“{eonrmued om aiebts Fase.) a

tron, ‘This,
the buresu's major te!
purity.”

TA NOTHER novel device, used for *

‘somewhat similar purpose, is the
“emanation electroscope.” Actually if

For instance, to measure the exact
Amount of “radon,” or radium. ‘Their

von tm an microscopic that it;

il
t
rH
Es
a

‘Why? Because lead shields the re-
search werker from the-desdly radia~
‘tons of gamma rays.

‘Dr. Curtiss opens up the 10-tor
radium asfe. He says it is the only
‘one of the kind in the entire worte
and is another “brain child” of the

_.—-Tgurest of Standards techoicians. I:
Tecessary st would howe e tenth o
‘America’s efifire radium sopply, whict
at = Tough guest totals about 50

and
600,000.

You note
compartments
test radium.
arranged
posed to
ment at
well with!

In front of each
‘3 inches thick.
are closed the scte:
of prote
end all
etter he opens the

‘The radium

+ = Wooden,

palt an
vused peceuse
against
“peta”

‘This safe, by the
one ‘sed by the
largest
‘house 50
the ma:
side was

‘The

+ room, bure

technicians, It is shout 3 feet by 7
feet by 2. It contains abt
200 milligrams, or two-tenths of
gram, This safe Js not lead lin
but contains lead plates for screen!
off the dangerous

~~ kept Mm an adjoining office. It

|



e.U:

st ~
6 7 t
Fp PROTONS
enced fy fay PATON
jg tora mancogke ij
e { RONEN CURVE FROM AUELSONICS €, 40 L460? 10605
e | Ia
% aint 3 ‘.
shy rm)
a
c irs a
AN 1 eee Oe } Te
4 x. !
fet
= t "
.
AN
2 ; 2
- iN es
. . ® r
e z 1
- |
“4 20 At ae ae ae 30 32 i a a
a " on
Fraure 128. RBE dose (rems) from thermal neutron beam.

Fravex 124, Absorbed dose (rade) from thermal neutron beam.
61

60
Ee


this, the points at 1.2 Mey and at 0.5 Mev were conned,
and this confirmed that the actual curve will

of the detailed structure of the cross-section curves. tow
ever, the accuracy ot the present would not q not warrant

amount involved in detail, -
na eteumal neutrons Fad anlar at bys Bay x ed

Gp enc ‘pati, on, The re oresent calculations overnged Mout this

Shows the Reak 88 well 8 the average Com

uted inthe present Tn comput val
or Agnre 18 | Br:} the pealc ay; om com cea e the m

thermal neutrons incident on a Jar;
iad of Feat is Gr appreniea 80 percent, Hence the rea.

obtained with et dosing ters ‘worn for purposes of
Ear deat q

istry should be corrected accor
‘Le., the reading should bi bated 1.8 bef Seated
Soaaerinesicr haras pis

Appendix 2, Flux Detectors
and Their Calibration

As the methods of dux measurement are different f

the various ener; Fanges, sven, tho the principles in-
volved are about the same, they eae Be ena
ing to neutron

. Mux measurement of thermal neu.
trons has received most effort because it ig basic to most
flux measurements in the other energy classifications,

A, Thermal Neutrons

Gne spproach to the absolute measurement of thermal
neutron. is clogely related to source calibration, be-
gatize it i8 Possible to produce 4 fix with = standard source
that is kno as accurately as the emission rate
Or Oe ae ae ae a ea 2, “stanatd
pile,” is merely a large gray in

maui. fa Ra-Be source, is placed. The fast
trons emitted, fro m the source are tition of so the

are lle, te oo of indium, 1,44 STaed toned
at Lid ev. The absolt
the source strength Q

66

volume of the standard pile, sap fble capture
and no escape of resonances nevtrons cyte nl Taust
equa! Q, Once the slowing down density in the
standard pile it is a simple tier toa a pa bh a thermal
flux from q, for it is necessary to know only the lifetime
of the newtrons in. te, eanily obtained rom the scat-
tering constants of carbon.

The standard pile fur, while reasonab!
is quite low, and activations intense enou;
foil counting can be obtained only with foils that
thick that an a)

int result

standard
unknown flax is also in graphite and if the f
is identical, Fone pe aes Sraphite ang Ht will be equally
‘hod. However, a correction for the perturbation must
taut when Taxes So beams are to be measured
relative to the standard pile, for instance, and for this
geometry the correction leaves an error of several percent.
A second method of absolute measurement of neutron
flux is by means of the reaction rate of an element whose
cross section is known, for

reactions /sec=nvNo, «)
where N is the number of atoms of reaction cross-section

He, gic, js cseentially the nya) as the
; saiigib eer deter-
1a trom te otal ose ection, The. best yalus ot
ped joa cross: cre see from the AEC compila-

ity,
Lo boron ig sty 1, ottere veral
vel ause I on ictly 1/v. age seve

mesons fr which the abecepiio cross suai

accural

fraction of geattering, for instance Wd ox indines,
elements differ from boron. as fi ie standards hecange thelr
absorption is a result of radioacti

(2,2) ua) process, and in addition they are not strictly 1/ kA

‘The reaction rate in a known amount of boron located in
@ neutron flux can be measured by a BF;-filled proportional

67