Problems
1.
Enetgy fnay be released duting: a chemical reaction, phase change, fusion reaction, ald fission
reaction. List the four changes in order ofincreasing energy released. [Appendix A]
phc.Sc
c'-Vr.-u,.'<
\ Lkrc,.iico{
r((\c}r;
,
Ule tbe irfan atiut belaw ta afipcr
Ciss,u,- , {-us,.un
q eslia
2.
Einsteint theory of special teJativity, in 1 905, sho\red that it was possible to coovert mass in to ene_rgy
(E = mc"). Fermi, in 1938, discovered fission when tryirg to artificially ransmutate uranium mto a
new element. The fission of uranium-235 can produce diffetent daughter products.
2.
\Ytite the complete fission reaction when one neutron collides with a u-tanium 235 to ptoduce
xenon-137, another daughter product and two free neuuons. lAppendix A]
235
92u
1
+
0n
ti1
----->
U*
tbe
*!Srif,in
.,
infaraatiol
below ta
afiwer
q ertia
3.
Both uanium-235 and plutonium-239 can undergo fission and are used to male atomic bombs. The
uranium-235 is obtairied from natual uranium ore whi.le plutonium is a b)?roduct of some reactors
such as the Canadian Candu reactors. Reactors that produce plutonium that can be used as weapoos
ate called bteeder reaclors. Plutonium'239 has a half-lfe of 24 110 years and undergoes alpha and
gzLmma decay.
3.
The fust nuclear weapon was detonated on July 16, 1945 at Tiriry test site in Alamogordo,
Ne.n' Mexico. It used 6.2 lg of plutonium-239 with an explosive power equivalent to 20
kilotons of TNT.
a. lfdte the decay equatioD for plutorium-239. [Appendix A]
b. Determine the amount of plutonium-239 remaining aftet 10 000 ),ears, stzrting with 6.2 kg.
[4.7 ks]
cr
.+
J.3jl
1., r'"
s
b
-r
= N,,,
= 6.
@
H"
u -, D,,
;z
lj5,r
'^.;;
(;)!/t',,
1k,
= q.r
Copyikht
j
, l '{oL6/
ze
I
'o
KS
Kennedy/oswald, O 2008
Chaprer 8 - 330
I
Uu
the inJannalon bekw to
anwer qaettiat 4.
Each of the thtee neutrons released dudng the
Ession ofa uranium-235 nuclei ate avaLlable to
collide with three more U-235 nuclei. In this
way a chain teaction is set up. Ifthere is
enough u-2J5 Presenl. Lhe chaL.,l reacEon
becomes uncontrolled. In this w-ay, much heat
energy and radiation is teleased. Ifyou have at
least a minimum mass ofU-235 present, called
crirjcal mr(.Iou mry get a nucleat explosion.
,;\
Kr
..--., , @
r\v / -
-
'n6)\ -/
-r@
^_ '-'---'@
n(u).......*nfi
1
@
_____*
J
,6
n,^------o'@
Q)------------ , 6)
--r-..*
Ba
,6
4.
Determine the total efletgl released after 2 sets in the chain reacuon ifeach fission teleases
200 MeV of energy. 1800 MeVl
,trcr l'.\<,'r
5.
r
3
( -1co
t'te!) '
8L"-
l'"\
t:
!
The quote below forms rhe end of Pierte Currie's Nobel Prize acceptance speech in 1903: lrell
before the development of atomic enetgv plants ot atomic weapons.
can even be thought that radium could become very daogerous in criminal hands,
aod here the question can be raised vthethet mankiod benefits from knowing the
sectets ofNature, $,hether it is ready to pto6t from it ot whether this knowledge
It
will not be harmhrl for it The example of t1,le discoveries of Nobel is characteristic,
as powerful explosives have enabled man to do wondetful work They are also a
€rIible means of destruction in the hands of geat criminals u'ho ate leadiflg the
peoples to*'atds war. I am one of those who belieVe with Nobel drat mankind will
derive more good than hanrr from the new drscoveries.
\Yould you agree with Curie that out knowledge of atomic energy has been put to mote good
than to harm? Explain. [APPendix A]
- fl\r( \t({-r ,^n< Cl'ci D{
1c.t-(( ' r-w-1-11q \'\(
'/
Copirlght O Iftnnedy/Osw:ld,
@ 2008
V-rcr
S
<-
chapter 8 -
331