The NJOY Nuclear Data Processing System, Volume 1:User's Manual

incoherent inelastic energy-to-energy matrices for free or bound scatterers,
coherent elastic cross sections for hexagonal materials, and incoherent elastic
cross sections. GROUPR generates self-shielded multigroup cross sections,
group-to-group neutron scattering matrices, and photon production matrices from
pointwise input. GAMINR calculates multigroup photon interaction cross sections
and kerma factors and group-to-group photon scattering matrices. ERRORR produces
multigroup covariance matrices from ENDF/B uncertainties. COVR reads the output
of ERRORR and performs covariance plotting and output formatting operations.
DTFR formats multigroup data for transport codes, such as DTF-IV5 and ANISN. 6
CCCCR formats multigroup data for the CCCC standard7 interface files ISOTXS,
BRKOXS, and DLAYXS. MATXSR formats multigroup data for the MATXS cross-section
interface file. The ACER module prepares libraries for the Los Alamos contin-
uous-energy Monte Carlo code MCNP.8 POWR prepares libraries for the EPRI-CELL
and EPRI-CPM codes.* Finally, MODER changes ENDF/B “tapes” and other ENDF-like
NJOY interface files back and forth between formatted (that is, BCD or ASCII)
and blocked-binary modes. NJOY incorporates and improves upon the features of
its direct ancestor, MINX.9 It also includes and extends the photon production
capabilities of LAPHANO,1° the photon interaction capabilities of GAMLEG,ll the
heating capabilities of MACK,12 the covariance capabilities of PUFF,13 and the
thermal capabilities of FLANGE-1114 and HEXSCAT.15
The methods used in these modules are described in detail in subsequent
volumes of this report. The following brief account will make the general flow
of the code clear. RECONR reads an ENDF/B tape and produces a common energy
grid for all reactions (the union grid) such that all cross sections can be
obtained to within a specified tolerance by linear interpolation. Resonance
cross sections are calculated with the methods of RESEND,16 but a new method of
choosing the energy grid is used that incorporates control of the number of
significant figures generated and a resonance-integral criterion to reduce the
number of grid points generated for some materials. Summation cross sections
(for example, total,
ing pointwise cross
future use. BROADR
method of SIGMA1,17
inelastic) are reconstructed from their parts. The result-
sections are
reads a PENDF
modified for
written onto a “point-ENDF” (PENDF) tape for
tape and Doppler-broadens the data using the
better behavior at high temperatures and low
*EPRI-CELL and EPRI-CPM are proprietary codes. Additional information can be
obtained from the Electric Phwer Rese~rch Institute, 3412 Hillview Ave, Palo
Alto, California 94394.
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