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234 Appendices

default value of 200 ms. By increasing the time interval to 600, for example, the decay process

will be painted at one third of the default speed onto the screen.

Start/Stop

With the Start button, the user starts the simulation with the chosen selections. During the

simulation, the applet can be stopped at any time by pressing the Stop button. With the

simulation halted, it is only possible to change the time-step, and then to restart. As soon as

the simulation is completed, the Stop button is automatically changed to a Start button and

all input and selection ﬁelds are again enabled.

Plot

As mentioned above, there are two different ways of showing the simulation. The ﬁrst one is

the Normal Plot where the number of protons Z in the nuclide is shown as a function of the

number of neutrons N. The second plot is the Compact Plot. In this case the quantity A − 2Z

is shown as a function of the number of protons Z, where A is the atomic number (N + Z).

This leads to a more compact representation of the decay scheme as shown in Fig. E.4.

Fig. E.4. Decay Chain Simulator: decay of

238

U–Compact Plot

Th232/U235/U238

With these buttons the user can simulate the three natural decay families (Th232, U235 and

U238) directly. These nuclides can of course also be selected through the use of the drop-down

menus.

MinBR (%) (Minimum Branching Ratio)

The branching ratio refers to the fraction of daughter nuclides produced from a parent nuclide

in the decay process. For some processes, such as cluster emission (discovered in the 1980s),

Appendix E: Universal Nuclide Chart 235

Fig. E.5. Decay of U234 with MinBR = 0, i.e. showing all decay processes such as cluster

emission. Cluster emission of Ne24+Ne26 from U234 gives rise to Hf184

the branching ratios are extremely small. In the decay of a parent nuclide, if all daughters

are shown, the decay chain will show many nuclides some of which are only present in tiny

amounts. For this reason a min

imum branching ratio, MinBR, can be set which allows the user

to “see” only daughters with branching ratios higher than MinBR.IfMinBR is set to zero,

all daughters are shown including extremely rare events such as cluster emission. In Fig. E.5

the decay of U234 is shown. As can be seen from the basic decay data, U234 shows cluster

emission of both Mg28 and Ne24+Ne26 to give Hg206 and Hf184 respectively. The default

value is MinBR = 10

−4

E(MeV)

Nuclides with high gamma activity can be indicated in the Decay Chain Simulator through

“blinking”. The ﬁeld E(MeV) shows the threshold gamma energy per disintegration in mega

electron volt (MeV) to initiate “blinking". This can be changed also while the simulation is

running. As decimal separator, a point (.) must be used. The default value is 0.5 MeV, and this

is also used when the user deletes the contents of the ﬁeld.

Metastable states of nuclides are indicated by a small insert in the top right corner of

the element box. If they have the same colour, a black border around the metastable state is

used to differentiate it from the ground state. If only the metastable state is part of the decay

chain, this is shown in the correct colour and the rest of the box is transparent. If there is no

information available on a daughter product, this is shown transparent and the decay scheme

ends there. Also, if all branching ratios of a nuclide are less than the threshold value for the

branching ratio or the branching ratios are not known, the nuclide is shown transparent with

no further daughters.

236 Appendices

Neutron Reaction Path Simulator

The Neutron Reaction Path Simulator window is shown in Fig. E.6. This application indicates

the main neutron reactions likely to occur with the selected nuclide in a nuclear reactor with

a thermal neutron spectrum, i.e. in most light water reactors (LWRs). The neutron reactions

occurring are based on the cross-sections, the burnout time and the half-life of the selected

nuclide.

The Selected Nuclide, in this case Th232 selected from the Nuclide Chart Viewer, is

shown in the box in the top left hand side of the window in Fig. E.6. The neutron reaction path

for this nuclide is shown in the main frame of the window.

Neutron Flux

The neutron ﬂux can be set in the taskbar in Fig. E.6. The default value of the neutron ﬂux is

3 × 10

neutrons cm

−2

−1

typical of light water reactors.

Fig. E.6. Neutron Reaction Path Simulator: transmutation of Th232 in a thermal neutron

ﬂux

Reaction Index

The reaction index, which can also be set in the taskbar, indicates the number of activation

products to be taken into account. In Fig. E.6, this value is set to 20 and the ﬁrst 20 activation

products are shown in the main window. The default value is 10.

Time Step

Here the user can “see” the activation or transmutation process in “slow motion” by changing

the time interval in which the products are painted onto the screen. The value is given in

milliseconds with a default value of 500 ms. By increasing the time interval to 1500, for

example, the transmutation will be painted at one third of the default speed onto the screen.

As explained in Chapter 3 (page 54), depending on the thermal neutron ﬂux, there is a

competition between decay and burnout processes. Consider the case of Th232 in a thermal

Appendix E: Universal Nuclide Chart 237

Fig. E.7. The reaction path of Th232 in a high thermal ﬂux. Notice that the production of U233

as shown in Fig. E.6 is bypassed

neutron ﬂux. With a half-life of 1.4 × 10

y and a burnout time of 9.9 y, the nuclide will

transmute to Th233. This nuclide has a half-life (22 m) shorter than the burnout time (18 d)

and will decay to Pa233. This protactinium isotope has a half-life of 27 d and a burnout time

of 1.8 y. It will therefore decay preferentially to the ﬁssile isotope U233. This uranium isotope

is highly desirable in the thermal reactor since it ﬁssions to produce energy. If however the

ﬂux in the reactor increases, the burnout time decreases. This implies that more Pa234 (which

decays to U234) is produced at the expense of U233. This can be demonstrated by setting the

ﬂux to a very high value of 5 × 10

neutrons cm

−2

−1

and restarting the calculation. The

reaction path in this very high ﬂux is shown in Fig. E.7.

On the other hand, in a low thermal neutron ﬂux the decay process will predominate over

the burnout process. The reaction path will be essentially the decay chain.

Reaction Products

In general, a nuclide in a nuclear reactor can transform via three main processes:

• by radioactive decay – to one or more daughter products

• by neutron (radiative) capture – to a nuclide with a mass increase of 1

• by neutron induced ﬁssion – to ﬁssion products

In some cases, all three processes can occur. As an example consider the nuclide Pu241.

The nuclide has a half-life of τ = 14.3 y, and capture and ﬁssion cross-sections of 361.6 b

and 1013 b respectively. In a neutron ﬂux of ϕ = 3 × 10

−2

−1

, the burnout time is

= 19.4 d. The branching ratios for decay, capture, and ﬁssion are:

decay

= λ/[λ + (σ

+ σ

) · ϕ]=0.004 or 0.4%

capture

= σ

· ϕ/[λ + (σ

+ σ

) · ϕ]=0.263 or 26.3%

ﬁssion

= σ

· ϕ/[λ + (σ

+ σ

) · ϕ]=0.733 or 73.3%

with the sum of the branching ratios equal to 1. In this example of Pu241, the reaction prod-

ucts are U237 (through alpha decay), Pu242 (through neutron capture), and ﬁssion products.

Clearly, a single nuclide can give rise to a number of reaction products. These reaction prod-

238 Appendices

ucts will also transform in the reactor through the above processes and quickly give rise to a

great number of nuclides.

In the Reaction Path Simulator, painting all these nuclides onto the screen would just

lead to confusion. In most cases, however, the branching ratios for many of these reaction

products are quite small and the corresponding processes can be neglected. For this reason,

in the Reaction Path Simulator, only the main reaction product with the highest branching

ratio (in the above example this is Pu242) is shown.

Acknowledgements

This chapter was compiled with the assistance of Ms.Yvonne Galla and Dr. Jean Galy.

Ms. Galla developed the Universal Nuclide Chart program module.

References

1. J. Magill, Y. Galla, J. Galy: The Universal Nuclide Chart: An Interactive Java-based Chart,

Technical Report JRC-ITU-TN-2001/29, Institute for Transuranium Elements, 2001

Appendix F: Periodic Table of the Elements 239

Appendix F

Periodic Table of the Elements

The Periodic Table of the Elements as shown on the next two pages has been reproduced

(and slightly modiﬁed) with permission from

The version reproduced is dated 7 November 2003.

For updates to this table see http://www.iupac.org/reports/periodic_table/.

240 Appendices

periodic table

Notes

• Aluminum and cesium are commonly used English-language spellings for aluminium and

caesium.

•

IUPAC 2001 standard atomic weights (mean relative atomic masses) are listed with uncertain-

ties in the last ﬁgure in parentheses [R. D. Loss: Pure Appl. Chem. 75, 1107–1122 (2003)].

These values correspond to current best knowledge of the elements in natural terrestrial

sources. For elements with no IUPAC assigned standard value, the atomic mass (in uniﬁed

atomic mass units) or the mass number of the nuclide with the longest known half-life is listed

between square brackets.

• Element with atomic number 111 has not yet been named. The IUPAC provisional name is

shown.

• Element with atomic numbers 112, 114, and 116 havebeen reported but not fully authenticated.

Appendix F: Periodic Table of the Elements 241

of the elements ( iupac)

Appendix G: Karlsruhe Chart of the Nuclides – Karlsruher Nuklidkarte 243

Appendix G

Karlsruhe Chart of the Nuclides – Karlsruher Nuklidkarte

6th edition 1995, revised reprint December 1998

Authors:

G. Pfennig, H. Klewe-Nebenius, W. Seelmann-Eggebert

Explanation of the Chart of the Nuclides

The data given in the chart were taken from the following sources:

Decay Data:

A = 3: D. R. Tilley, H. R. Weller, H. H. Hasan: Nuclear Physics A474, 1 (1987)

A = 4: D. R. Tilley, H. R. Weller, G. M. Hale: Nuclear Physics A541, 1 (1992)

A = 5–15: F.Ajzenberg-Selove: Nuclear Physics A490, 1 (1988); A506, 1 (1990);

A523, 1 (1991)

A = 16–17: D. R. Tilley, H. R. Weller, C. M. Cheves: Nuclear Physics A564, 1 (1993)

A = 18–20: F.Ajzenberg-Selove: Nuclear Physics A475, 1 (1987)

A = 21–44: P. M. Endt: Nuclear Physics A521, 1 (1990)

A ≥ 45: Nuclear Data Sheets (incl. Recent References) 1–75, 1 (1966–1995)

In addition, original publications up to October 1998 were taken into account.

Neutron Cross Sections:

N. E. Holden: Table of Isotopes (Revised 1991). CRC Handbook of Chemistry and Physics,

72nd edition (1991–1992), pp. 11–28, D. R. Lide (ed.). CRC Press, Boca Ration, Florida

Natural Isotopic Abundances and Atomic Weights:

J. R. De Laeter: IUPAC, Commission on Atomic Weights and Isotopic Abundances: Pure and

Applied Chemistry 63, 991 (1991)

K. G. Heumann: Pure and Applied Chemistry 66, 2423 (1994)

Cumulative Chain Yields for the Thermal Neutron Fission of

235

M. F. James, R. W. Mills, D. R. Weaver: Report AEA-TRS-1018 (1991)

General

In this chart of nuclides each experimentally observed nuclide is represented by a square

containing the symbol of the element and the number of nucleons. If no half-life is given, the

respective nuclide is either unstable with regard to particle emission (white ﬁeld specifying the

emitted particles), or a radionuclide with unknown decay properties, which has been detected

as shortlived reaction product only. Metastable states, which do not undergo α-, or β-decay,

or spontaneous ﬁssion, thus, decaying exclusively to the ground state of the same nuclide, are

included only, if their half-life is larger than 1 s.

For isomers, which decay exclusively via spontaneous ﬁssion, no decay data are given. A

compilation of the half-lives, which are all less than 14 ms can be found e.g. in W. B. Ewbank

et al., Nucl. Data Sheets 26, 1 (1979).

In the chart the nuclides are arranged in such a way that the proton number Z is given on the

ordinate and the neutron number N = A − Z on the abscissa, respectively. This arrangement

was originally proposed by E. Segr`e.