Table 6.7.1 Spontaneous Fission Nuetron Yields

DOE-STD-1128-98

Table 6.7.1 Spontaneous Fission Nuetron Yields

Spontaneous

Sponatenous

Half-Life,

Fission Yield,

Isotope

Total Half-Life

years

n/sec-gram

1.41 x 1010 y

>1 x 1021

>6 x 10-8

232

232U

71.7 y

8 x 1013

1.3

233U

1.59 x 105 y

1.2 x 1017

8.6 x 10-4

234U

2.45 x 105 y

2.1 x 1016

5.02 x 10-3

235U

7.04 x 108 y

3.5 x 1017

2.99 x 10-4

236U

2.34 x 107 y

1.95 x 1016

5.49 x 10-3

238U

4.47 x 109 y

8.20 x 1015

1.36 x 10-2

237Np

2.14 x 106 y

1.0 x 1018

1.14 x 10-4

238Pu

87.74 y

4.77 x 1010

2.59 x 103

239Pu

2.41 x 104 y

5.48 x 1015

2.18 x 10-2

240Pu

6.56 x 103 y

1.16 x 1011

1.02 x 103

241Pu

14.35 y

2.5 x 1015

5 x 10-2

242Pu

3.76 x 105 y

6.84 x 1010

1.72 x 103

241Am

433.6 y

1.05 x 1014

1.18

242Cm

163 days

6.56 x 106

2.10 x 107

244Cm

18.1 y

1.35 x 107

1.08 x 107

249Bk

320 days

1.90 x 109

1.0 x 105

252Cf

2.646 y

85.5

2.34 x 1012

1 Adapted

from NUREG/CR-5550 (Reilly et al., 1991)

Energetic alpha particles can overcome coulomb barriers in low-atomic-

number elements and create an unstable nucleus that emits neutrons.

Because of the high alpha activity of plutonium, this can be a significant

source of neutrons. There are two nuclear reactions that are of

importance:

α + 18O → 21Ne + n

(6.6)

α + 19F → 22Na + n.

(6.7)

Table 6.8 contains the alpha-neutron yields for oxides and fluorides for

the most common plutonium and transuranic nuclides. Note that the

neutron yields are normalized per gram of nuclide, not per gram of

compound. To obtain the yields per gram of compound, multiply by 0.88

for PuO2 and 0.76 for PuF4. These data are taken from NUREG/CR-5550

(Reilly et al., 1991).

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