 |
|||
|
|
|||
|
Page Title:
Table 6-10. Release Fraction for Various Chemical Classes from Heated Spent Fuel |
|
||
| ||||||||||
|
|  DOE-HDBK-3010-94
6.0 Inadvertent Nuclear Criticality; Material Release in Criticality Excursions
Table 6-10. Release Fraction for Various Chemical Classes from Heated Spent Fuel
(Restrepo, 1991)
Group #
Group Name
Rep. Ele.
Elements in Group
ARF
1
Noble Gases
Xe
Xe, Kr, He, Ne, Ar, Rn, H
5E-1
2
Alkali Metals
Cs
Cs, Rb, Li, K, Fr, Na
2E-1
3
Alkali Earths
Ba
Ba, Sr, Mg, Ca, Ra, Be
3E-2
4
Halogens
I
I, F, Cl, Br, At
5E-2
5
Chalogens
Te
Te, S, Se, O, Po, N
7E-2
6
Platinoids
Ru
Ru, Rh, Pd, Os, Ir, Pt, Au, Ni
2E-3
7
Transition Metals
Mo
Mo, V, Cr, Fe, Co, Mn, Nb, Tc
3E-2
8
Tetravalent
Ce
Ce, Ti, Zr, Hf, Th, Pa, U, Np Pu
4E-4
9
Trivalent
La
La, Al, Sc, Y, Ac, Pr, Nd, Pm,
6E-4
Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm,
Yb, Lu, Am, Bk, Cf
10
Main Group I
Cd
Cd, Hg, Zn, As, Sb, Pd, Tl, Bi
4E-3
11
Main Group II
Sn
Sn, Ca, In, Ag
4E-3
12
Boron
B
B, Si, P, C
6E-4
5E-4 of all non-volatile materials released to the moderator are released to the ambient
environment (e.g. Group #2 2E-1 X 5E-4 = 1E-4). Since quantities will be small and the
excursion does not generate sufficient energy to fail particulate filters on the exhaust system,
the contribution of the airborne nonvolatile materials to ex-facility doses is generally ignored.
If the material involved is a ceramic oxide powder, no melting/softening is postulated that no
significant fraction of the non-volatile fission products generated are released. Due to the
size of the individual particles in a powder, it is assumed that the fraction of volatile fission
products (noble gases, iodine, ruthenium) present are so close to the surface that they are
released in the following fractions: 5E-1 of the noble gases; 5E-2 of the iodine; and, 2E-3 of
the ruthenium.
Other groupings of radionuclides are possible. For instance, ruthenium is unique in that it
can readily form volatile oxides under appropriate conditions. Ruthenium could be logically
included with the Transition Metals increasing its release fraction from 2E-3 to 3E-2 (greater
than an order-of-magnitude increase). The ARF for the Alkali Metals is 4 times greater than
for the Halogens and is difficult to justify. Generally, the elements in the Main Group I
elements appear to be more volatile than the elements included in the Main Group II category
although both are assigned the same ARF. The role of cladding is critical for the Chalogens
(Group V) elements especially Te for which significant interactions with the cladding are
predicted in all but very oxidizing conditions. Ba releases appear to be high and such values
only occur for very reducing conditions. The ARFs are those determined from the
Page 6-23
|
|
Privacy Statement - Press Release - Copyright Information. - Contact Us |
Click
here for thousands of PDF manuals