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JENDL/FPY-2011(corrected version)
Apr. 2017
Futoshi MinatoNuclear Data Center at JAEAThe 2nd modified version of JENDL/FPY-2011 was released in Sep. 2016. This update corrected someabnormally large fission product yields of 235U thermal neutron fission, as seen in Ref. [1].
However, an error in the modified JENDL/FPY-2011 released in Sep. 2016 has been found. The
problem is due to the fact that there is a bug in the computer code generating JENDL/FPY-2011,
which fails to correctly load some isomers from the ENDF/B-VI fission yield data, which was chosen as
the base of JENDL/FPY-2011. The isomers affected by the reading failure are 72mGa, 71mGe, 84mAs,109mRu, 122mAg, 130mIn, 128mSn, 125mXe, and 169mYb. Their fission yields are significantly different from thecorrect values. Other nuclides also deviate from correct values due to the normalization process. This
problem is found only in the 235U fission yield data from the version of JENDL/FPY-2011 released in
May 2016 and Sep. 2016, and does not exist in the 1st version released in Jul. 2012.
A new version without the aforementioned bug has been produced. We shall refer the correctedversion as JENDL/FPY-2011 (Feb. 2017) and the old version as JENDL/FPY-2011 (Sep. 2016)
hereafter. The mass yields of the JENDL/FPY-2011 (Sep. 2016) and JENDL/FPY-2011 (Feb. 2017) are
briefly shown in Fig. 1. The spike observed at A=128 is due to 128mSn. We also show the decay heat𝑓(𝑡) for 235U fission resulting from instant neutron radiation calculated by JENDL/FPY-2011 (Sep.
2016) and JENDL/FPY-2011 (Feb. 2017), and its ratio of JENDL/FPY-2011 (Feb. 2017) toJENDL/FPY-2011 (Sep. 2016) in Fig. 2. Tables B1-B3 in Document_B1-3.PDF list the independent
fission yields of JENDL/FPY-2011 (Sep. 2016) and JENDL/FPY-2011 (Feb. 2017), and Tables C1-C3 inDocument_C1-3.PDF list the cumulative fission yields. The percent difference, defined as(𝑌𝑆𝑒𝑝 − 𝑌𝐹𝑒𝑏 )⁄𝑌𝑆𝑒𝑝 × 100, is shown in the last column.
We apologize for this inconvenience.
References[1] J. Katakura, F. Minato, K. Ohgama, “Revision of the JENDL FP Fission Yield Data,” EPJ Web ofConferences 111, 08004 (Mar. 2016).
[2] Dickens, J.K. et al., “Fission Product Energy Release for Time following Thermal Neutron Fission of 235U
between 2 and 14,000 seconds,” Oak Ridge National Laboratory, ORNL/NUREG-14 (1977); J.K. Dickens et al..
Nucl. Sci. Eng., 74, p.106 (1980).
[3] Akiyama, M. et al., J. Atom. Ener. Soc. of Japan, 24, p.709 (1982) [in Japanese]; Akiyama, M. et al., ibid., 24,p.803 (1982) [in Japanese]; Akiyama, M. and An, S. “Measurement of fission product decay heat for fast reactor,”
Proc. of Int. Conf. on Nucl. Data for Science and Technol., Antwerp, Belgium, p.237 (1982).

Fig. 1: Independent fission yields for 235U as a function of mass for JENDL/FPY-2011 (Sep. 2016)
and (Feb. 2017). The results of thermal neutrons (nth, right), fast neutrons (nf, middle), and highenergy neutrons (nh=14 MeV, right) are shown. Bottom panels show the ratios of independent
fission yields of JENDL/FPY-2011 (Feb. 2017) to JENDL/FPY-2011 (Sep. 2016) for thermal (left),fast (middle), and 14 MeV (right), respectively.

Fig. 2: Top panels are the decay heat of 235U as a function of time for JENDL/FPY-2011(Sep.2016) and (Feb. 2017). The registered data for thermal neutrons (nth, right), fast neutrons(nf, middle), and high energy neutrons (nh=14 MeV, right) are shown. Experimental data takenfrom [2] and [3] are shown for thermal fission and fast neutron fission, respectively. Bottompanels show the ratios of decay heat of JENDL/FPY-2011 (Feb. 2017) to JENDL/FPY-2011 (Sep.
2016) for thermal (left), fast (middle), and 14 MeV (right), respectively.