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RSICC CODE PACKAGE DLC-221

1. NAME AND TITLE OF DATA LIBRARY

YUMMY: Multi-Temperature, Neutron Cross Section Library Based on ENDF/B-V

and ENDF/B-VI for use with MCNP.

2. NAME AND TITLE OF DATA RETREIVAL PROGRAMS

The MAKXSF code, which is distributed with the Los Alamos National Laboratory’s MCNP code, can be used to convert cross section libraries between ASCII and binary formats.

3. CONTRIBUTOR

Oak Ridge National Laboratory, Oak Ridge, Tennessee.

4. HISTORICAL BACKGROUND AND INFORMATION

Point-wise cross sections that exist in most MCNP neutron libraries contain data for room temperature, i.e., at 294K. Some isotopes contain data generated at one or more temperatures other than the room temperature. The availability of data for a wider range of temperatures is important for applications such as criticality safety. For this purpose, point-wise cross sections in ACE format were generated for 134 nuclides at 7 temperatures, including 0K, 294K, 373.15K, 423.15K, 473.15K, 523.15K, 587K. These cross sections are called YUMMY (YUcca Mountain MCNP-librarY).

5. APPLICATION OF THE DATA

YUMMY data were used in MCNP4c for a criticality benchmark problem selected from the International Handbook of Evaluated Criticality Safety Benchmark Experiments; LEU-COMP-THERM-003. The benchmark model contains 23 cases and includes water moderated U(2.35)O₂ fuel rods in 1.6840-cm square-pitched arrays. The new cross-section library was also used in MCNP4c for a PWR reactor design, and PWR and BWR waste packages to calculate the multiplication factor. The results are generally in good agreement compared to those that use the library distributed with MCNP4c, at room temperature. Discrepancies between YUMMY and the cross sections distributed with MCNP4c are a result of the different NJOY versions and options used, in generating these libraries.

6. SOURCE AND SCOPE OF DATA

Data in the YUMMY neutron cross section library are based on ENDF/B-V and ENDF/B-VI. The NJOY99.90 code was used to generate the point-wise cross sections. In NJOY, a 0.1% tolerance was utilized in the RECONR, BROADR and THERMR modules. For data generation at 0K, only the RECONR and ACER modules were used.

YUMMY contains 134 nuclides as listed in Table 1. This table lists nuclide identifiers in the MCNP library and source of data. In the new library, ENDF/B-V based data have nuclide identifier extensions of 80c, 81c, 82c, 83c, 84c, 85c and 86c for 0K, 294K, 373.15K, 423.15K, 473.15K, 523.15K, 587K, respectively. For ENDF/B-VI, extensions 91c, 92c, 93c, 94c, 95c and 96c are used. For example, 92238.80c corresponds to ²³⁸U cross sections based on ENDF/B-V at 0K.

7. DISCUSSION OF THE DATA RETRIEVAL PROGRAM

The code MAKXSF, which is distributed with MCNP, performs conversion between formatted, sequential access (ASCII) files and unformatted, direct access (binary) files.

8. DATA FORMAT AND COMPUTER

ASCII and binary; Unix workstations or PC (D00221MNYCP00)

Two forms of the library are included in the package: ASCII and big endian binary. Both formats were tested on UNIX platforms. The big endian format was successfully tested on both DEC Alpha and IBM AIX platforms. The GNU compressed data are distributed in Unix tar files. Windows users can extract from the distribution files using WinZIP 8.0 or newer, then the individual *.gz files can be expanded with WinZIP.

9. TYPICAL RUNNING TIME

Not applicable.

10. REFERENCES

a. Documentation available with library:

F. A. Alpan and M. E. Dunn, “YUMMY: The YUcca Mountain MCNP-librarY,” Draft report ORNL/TM-2204/124 (June 2004).

b. Other useful documentation:

R. E. MacFarlane, “NJOY99.00: Code System for Producing Pointwise and Multigroup Neutron and Photon Cross Sections from ENDF/B Data,” RSICC Code Package PSR-480, Los Alamos National Laboratory, Los Alamos, New Mexico (March 2000).

“MCNP5: Monte Carlo N-Particle Transport Code System,” RSICC Code Package CCC-710, Los Alamos National Laboratory, Los Alamos, New Mexico (2003).

11. CONTENTS OF LIBRARY

The referenced document in 10.a, cross section libraries and xsdir files are provided on 2 CDs or on 1 DVD.

12. DATE OF ABSTRACT

September 2004.

KEYWORDS: BASED ON ENDF/B-V; BASED ON ENDF/B-VI; MCNP

FORMAT; NEUTRON CROSS SECTIONS

Table 1: List of Nuclides in YUMMY

Symbol	MCNP ID (extensions not included)	Evaluation Source Used^*
h1	1001	b-v.0
h3	1003	b-v.0
he4	2004	b-v.0
li6	3006	b-v.0
li7	3007	b-v.2
be9	4009	b-v.0
B10	5010	b-v.0
b11	5011	b-vi.0
c	6000	b-v.0
n14	7014	b-v.0
o16	8016	b-v.0
f19	9019	b-v.0
na23	11023	b-v.0
mg	12000	b-v.0
al27	13027	b-v.0
si	14000	b-v.0
p31	15031	b-v.0
s32	16032	b-v.0
cl	17000	b-v.0
k	19000	b-v.0
ca	20000	b-v.0
ti	22000	b-v.0
v	23000	b-v.0
cr	24000	b-v.0
cr50	24050	b-vi.1
cr52	24052	b-vi.1
cr53	24053	b-vi.1
cr54	24054	b-vi.1
mn55	25055	b-v.0
fe	26000	b-v.0
fe54	26054	b-vi.1
fe56	26056	b-vi.1
fe57	26057	b-vi.1
fe58	26058	b-vi.1
co59	27059	b-v.0
ni	28000	b-v.0
ni58	28058	b-vi.1
ni60	28060	b-vi.1
ni61	28061	b-vi.1

Symbol	MCNP ID (extensions not included)	Evaluation Source Used^*
ni62	28062	b-vi.1
ni64	28064	b-vi.1
cu	29000	b-v.0
cu63	29063	b-vi.2
cu65	29065	b-vi.2
as75	33075	b-v.0
kr80	36080	b-v.0
kr82	36082	b-v.0
kr83	36083	b-v.0
kr84	36084	b-v.0
kr86	36086	b-v.0
y89	39089	b-v.0
zr	40000	b-vi.1
zr93	40093	b-v.0
nb93	41093	b-v.0
mo	42000	b-v.0
mo95	42095	b-v.0
tc99	43099	b-v.0
ru101	44101	b-v.0
ru103	44103	b-v.0
rh103	45103	b-v.0
rh105	45105	b-v.0
pd105	46105	b-v.0
pd108	46108	b-v.0
ag107	47107	b-vi.0
ag109	47109	b-vi.0
cd	48000	b-v.0
in	49000	b-vi.0
xe131	54131	b-v.0
xe134	54134	b-vi.0
xe135	54135	b-v.0
cs133	55133	b-v.0
cs135	55135	b-v.0
ba138	56138	b-v.0
pr141	59141	b-v.0
nd143	60143	b-v.0
nd145	60145	b-v.0
nd147	60147	b-v.0
nd148	60148	b-v.0

Symbol	MCNP ID (extensions not included)	Evaluation Source Used^*
pm147	61147	b-v.0
pm148	61148	b-v.0
pm149	61149	b-v.0
sm147	62147	b-v.0
sm149	62149	b-v.0
sm150	62150	b-v.0
sm151	62151	b-v.0
sm152	62152	b-v.0
eu151	63151	b-vi.0
eu152	63152	b-v.0
eu153	63153	b-vi.7
eu154	63154	b-v.0
eu155	63155	b-v.0
gd152	64152	b-v.0
gd154	64154	b-v.0
gd155	64155	b-v.0
gd156	64156	b-v.0
gd157	64157	b-v.0
gd158	64158	b-v.0
gd160	64160	b-v.0
ho165	67165	b-vi.5
hf	72000	b-v.0
ta181	73181	b-v.0
ta182	73182	b-vi.0
w182	74182	b-v.2
w183	74183	b-v.2
w184	74184	b-v.2
w	74000	b-v.2
w186	74186	b-v.2
pb	82000	b-v.0
th232	90232	b-v.0
pa233	91233	b-v.0
u233	92233	b-v.0
u234	92234	b-v.0
u235	92235	b-v.0
u236	92236	b-v.0
u237	92237	b-v.0
u238	92238	b-v.0
np237	93237	b-v.0

Symbol	MCNP ID (extensions not included)	Evaluation Source Used^*
np238	93238	b-vi.2
pu237	94237	b-vi.0
pu238	94238	b-v.0
pu239	94239	b-v.2
pu240	94240	b-v.0
pu241	94241	b-v.0
pu242	94242	b-v.0
am241	95241	b-v.0
am242m	95242	b-v.0
am243	95243	b-v.0
cm242	96242	b-v.0
cm243	96243	b-vi.7
cm244	96244	b-v.0
cm245	96245	b-vi.7
cm246	96246	b-vi.7
cm247	96247	b-vi.2
cm248	96248	b-vi.0

*: ENDF/B evaluation denoted with b-{version number}.{release number}. e.g. b-v.0 refers to ENDF/B-V Release 0