Curium



This article is about the chemical element Curium; for the ancient city also called Curium (located in Cyprus), see Kourion
96 berkelium
Gd
↑
Cm
↓
(Uqh)
General
Number curium, Cm, 96
actinides
Block f
Appearance silvery
Standard atomic weight (247)  g·mol−1
Rn] 5f7 6d1 7s2
shell 2, 8, 18, 32, 25, 9, 2
Physical properties
Phase solid
r.t.) 13.51  g·cm−3
F)
F)
kJ·mol−1
Vapor pressure
P(Pa) 1 10 100 1 k 10 k 100 k
at T(K) 1788 1982        
Atomic properties
Crystal structure hexagonal close-packed
amphoteric oxide)
Electronegativity 1.3 (Pauling scale)
Ionization energies 1st: 581 kJ/mol
Miscellaneous
Magnetic ordering no data
CAS registry number 7440-51-9
Selected isotopes
Main article: Isotopes of curium
iso NA half-life DM DE (MeV) DP
242Cm syn 160 days SF - -
α 6.1 238Pu
243Cm syn 29.1 y α 6.169 239Pu
ε 0.009 243Am
SF - -
244Cm syn 18.1 y SF - -
α 5.902 240Pu
245Cm syn 8500 y SF - -
α 5.623 241Pu
246Cm syn 4730 y α 5.475 242Pu
SF - -
247Cm syn 1.56×107 y α 5.353 243Pu
248Cm syn 3.40×105 y α 5.162 244Pu
SF - -
250Cm syn 9000 y SF - -
α 5.169 246Pu
β- 0.037 250Bk
References

Curium (Pierre.

Contents

Notable characteristics

The bio-accumulates in bone tissue where its radiation destroys bone marrow and thus stops red blood cell creation.

A compounds are slightly yellow).

Curium has been studied greatly as a potential fuel for radioisotope thermoelectric generators (RTG). Curium-242 can generate up to 120 beta radiation from radioactive decay products.

Compounds

Some compounds are:

  • -curium dioxide (CmO2)
  • -curium trioxide (Cm2O3)
  • -curium bromide (CmBr3)
  • -curium chloride (CmCl3)
  • -curium tetrafluoride (CmF4)
  • -curium iodide (CmI3)

History

Curium was americium-241 with neutrons. Curium was made in its elemental form in 1951 for the first time.

Isotopes

19 u (Cm-233) to 252.085 u (Cm-252).

243Cm244Cm245Cm246Cm247Cm
27.64%70.16%2.166%0.0376%0.000928%

MOX fuel irradiated in a fast reactor (average of 5 samples with burnup 66 to 120GWd/t) [1] contained 3.09×10-3% curium with isotopic content:

243Cm244Cm245Cm
513700390

The proportions of the three most common curium isotopes in 53 MWd/kg LEU spent fuel 20 years after discharge were reported in [2] (page 4) as:


242Cm243Cm244Cm245Cm246Cm247Cm
Fission56171.0421450.1481.90
Capture1613015.203691.2257
C/F ratio3.200.2114.620.178.710.70

Neutron cross sections (mostly for 2200m/s neutrons):

The pattern is that the odd-mass number isotopes are fissile, the even-mass number isotopes are not and can only neutron capture, but very slowly. Therefore the even-mass isotopes accumulate in a thermal reactor as burnup increases.

Nuclear fuel cycle

The neutron emitter. The californium would pollute the back end of the fuel cycle and increase the dose to workers. Hence if the minor actinides are to be used as fuel in a thermal neutron reactor, the curium should be excluded from the fuel or placed in special fuel rods where it is the only actinide present.

References

  • Los Alamos National Laboratory - Curium
  • Guide to the Elements - Revised Edition, Albert Stwertka, (Oxford University Press; 1998) ISBN 0-19-508083-1
  • It's Elemental - Curium
  • Human Health Fact Sheet on Curium
 
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