Fission Product Yield Data for the Transmutation of Minor Actinide ...

For the dip at A = 130:
n ( A) = I [ e D ] / pC
H D
142
-( A-130) C 2 /
(4.2.22f)
I D = –5.0 (4.2.22g)
C D = 2.0(3.0 2 + 1/12) = 18.17 (4.2.22h)
For the light dip complementary to A = 130:
n ( A) = I [ e C D]
/ pC
L D
(4.2.22i)
S C = A F – 130.0 – (V F – D H + S H ) (4.2.22j)
DH = ID/ pCD
2 -( A-S ) / C
S = I [ e D ] / pC
H D
2 /
-( 130. 0-SYM)
C
(4.2.22k)
(4.2.22l)
SYM = (A F – n s )/2.0 (4.2.22m)
4.2.4.5. Model for R(A)
Generalized R(A) functions consist of a
number of straight line segments chosen to give
sawtooth n A (A) functions with some inflections.
Two R(A) functions are shown in Figs 4.2.39 and
4.2.40, and equations for the segments in the various
regions designated in Figs (4.2.39) and (4.2.40) are
given below. Note that Eqs (4.2.23c) and (4.2.23f)
are excitation energy dependent continuous
functions that approximate the former discrete
values [4.2.4, 4.2.29].
A < D: R(A) = 0.20 (4.2.23a)
A = D to F: R(A) = 0.2 + (A – D)(R(F) – 0.2)/(F – D)
(4.2.23b)
A = F to G: R(A) = 0.9 – 0.0075(PE) (4.2.23c)
A = G to H: R(A) = 0.5 + (H – A)(R(G) – 0.5)/(H – G)
(4.2.23d)
A = H to J: R(A) = 0.5 – (A – H)(0.5 – R(J))/(J – H)
(4.2.23e)
A = J to K: R(A) = 0.1 + 0.0075(PE) (4.2.23f)
D
D
D
FIG. 4.2.39. Fraction R(A) of n T (A) to A for U235T.
FIG. 4.2.40. Fraction R(A) of n T(A) to A for 238 U + 85 MeV p.
A = K to M:
R(A) = R(K) + (A – K)(0.8 – R(K))/(M – K) (4.2.23g)
A > M: R(A) = 0.80 (4.2.23h)
The n A (A) functions derived from the above
equations for two fission reactions are compared
with the experimental data in Figs 4.2.41 and 4.2.42
(U235T: Refs [4.2.39-4.2.42]; CF252S: Refs [4.2.43–
4.2.47]). As can be seen, the model n A (A) functions
represent the data moderately well, and to the same
extent as the different data sets for each fission
reaction agree with each other. The inflection in the
n A(A) model function near A = 105 is also exhibited
by the data, and is related to the light dip in the
n T (A) function. The significant dip in n T (A) is
reinforced by the minimum of R(A) at J to K to give
the n A (A) minimum just below A = 130. The above
equations are used in the CYF yield calculation
program.