Cross Section Evaluation Working Group (CSEWG) Announces the Release of the ENDF/B-VIII.0 Evaluated Nuclear Reaction Data Library

On February 2, 2018, CSEWG released its latest revision of the ENDF/B library, ENDF/B-VIII.0.

ENDF/B-VIII.0 fully incorporates the new Neutron Data Standards, includes improved thermal neutron scattering data and uses new evaluated data from the Coordinated International Evaluation Library Organization (CIELO) pilot project for neutron reactions on ¹H, ¹⁶O, ⁵⁶Fe, ²³⁵U, ²³⁸U and ²³⁹Pu. The evaluations benefit from recent experimental data obtained in the U.S. and Europe, and improvements in theory and simulation. Notable advances include updated evaluated data for light nuclei, structural materials, actinides, fission energy release, prompt fission neutron and gamma-ray spectra, thermal neutron scattering data, and charged-particle reactions.

CSEWG has performed integral validation testing on a wide range of criticality, reaction rate, and neutron transmission benchmarks. In general, our integral validation demonstrates that performance of the library is a noticeable improvement over the previous ENDF/B-VII.1 library.

Library Summary

Below we show the contents of the ENDF/B-VII.1 library, with ENDF/B-VII.0 and ENDF/B-VI.8 shown for comparison. NSUB stands for the sublibrary number in the ENDF-6 format. Given in the last three columns are the number of materials (isotopes or elements).

No.	NSUB	Sublibrary Name	Short Name	VIII.0	VII.1	VII.0	VI.8
1	0	Photonuclear	g	163	163	163	-
2	3	Photo-atomic	photo	100	100	100	100
3	4	Radioactive decay	decay	3821	3817	3838	979
4	5	Spont. fis. yields	sfy	9	9	9	9
5	6	Atomic relaxation	atom_relax	100	100	100	100
6	10	Neutron	n	557	423	393	328
7	11	Neutron fis. yields	nfy	31	31	31	31
8	12	Thermal scattering	tsl	34	21	20	15
9	19	Standards	std	10	8	8	8
10	113	Electro-atomic	e	100	100	100	100
11	10010	Proton	p	49	48	48	35
12	10020	Deuteron	d	5	5	5	2
13	10030	Triton	t	5	3	3	1
14	20030	3He	he3	3	2	2	1
15	20040	4He	a	1	-	-	-

1. The photonuclear sublibrary was carried over unchanged from ENDF/B-VII.0. It contains evaluated cross sections for 163 materials (all isotopes) mostly up to 140 MeV. The sublibrary was supplied by Los Alamos National Laboratory (LANL) and it is largely based on the IAEA-coordinated collaboration completed in 2000.
2. The photo-atomic sublibrary was updated as part of the EPICS2017 project. See the EPICS2017 page for more detail.
3. The decay data sublibrary has been improved by the Brookhaven National Laboratory (BNL).
4. The spontaneous fission yields were taken over from ENDF/B-VII.1
   
5. The atomic relaxation sublibrary was updated as part of the EPICS2017 project. See the EPICS2017 page for more detail.
6. The neutron reaction sublibrary represents the heart of the ENDF/B-VIII.0 library. The sublibrary has been updated and extended, and it contains 557 materials, including the 6 CIELO evaluations (¹H, ¹⁶O, ⁵⁶Fe, ²³⁵U, ²³⁸U and ²³⁹Pu).
7. Neutron fission yields were taken over from ENDF/B-VII.1.
8. The thermal neutron scattering sublibrary underwent significant revisions.
9. The neutron data standards sublibrary was substantially updated. See the Neutron Data Standards page for details.
10. The electro-atomic sublibrary was updated as part of the EPICS2017 project. See the EPICS2017 page for more detail.
11. The proton-induced reactions were carried over from ENDF/B-VII.0 with only minor corrections. These were supplied by LANL and the data being mostly to 150 MeV.
12. The deuteron-induced reactions were supplied by LANL, modified by LLNL. This sublibrary contains 5 evaluations.
13. The triton-induced reactions were supplied by LANL, modified by LLNL and now includes 5 evaluations.
14. Reactions induced with ³He were supplied by LANL, carried over mostly unchanged from ENDF/B-VII.0. This sublibrary contains 3 evaluations, including revisions from LLNL.
15. A new ⁴He sublibrary was added by LLNL. At this point, only ⁴He-⁴He elastics scattering is part of the sublibrary.

50 Years of ENDF

The U.S.'s Evaluated Nuclear Data File (ENDF) is the default low energy nuclear data library in particle transport codes such as MCNP, SCALE and even GEANT4. ENDF/B provides:

• Neutron reaction data needed for simulating nuclear systems
• Particle transport data and decay data used for health physics shielding calculations
• Activation and decay data needed for spent fuel modeling
• Charged-particle reaction data for fusion applications

The ENDF library has been under continuous improvement since 1968, the year the Cross Section Evaluation Working Group (CSEWG) released ENDF/B-I. CSEWG is a long-running collaboration between members of several DOE and other programs (Criticality Safety, Office of Science, Defense Programs, Naval Reactors, Nuclear Energy, NIST, & others), industry and international partners. 2018 marks the 50^th anniversary of the ENDF library.