Help calculating angular distributions in U235 / U238 with ENDFVIII data

[sombrereau]

NJOY team (@whaeck / @nathangibson14 ),

I'm a very new NJOY user. I'm trying to generate the covariance data with NJOY to calculate the nuclear data uncertainty for a potential Uranium Fueled Advanced Nuclear Reactor.

I'm getting errors when I try to process the ENDFVIII U235 / U238 nuclear data to create tapes for covariance of angular distribution.

NJOY issues the following message:

error in covcallb= 2 when lt= 1

I've tried to include every reaction in the endf data in my input and also tried to run test 15 (with the ENDFVIII nuclear data), and I've tried to use the preliminary INDEN ENDF evaluation with updated covariance data

I'm running NJOY21 v. 1.1.1. I'm using the attached input file.

Thanks for any tips,

-Tommy Cisneros

[whaeck]

This appears to be a violation of the ENDF format. Section 33.2.2.2 of the ENDF manual states:

For LB=0, 1 and 2 we have LT=0, i.e., only one Ek table. For LB=3 and LB=4 we have LT != 0, i.e., two E-tables, the Ek and the El-tables.

ERRORR appears to be strictly enforcing this rule. Whether this is an evaluation error, or ERRORR being unnecessarily pedantic, I cannot say. Either way, you should talk to the evaluator to get a corrected evaluation for your INDEN evaluation.

I did not run the input so I would like to ask if this happens for ENDF/B-VIII as well?

[sombrereau]

Thanks for looking at this Wim,

I just double checked with the ENDFVIII data and the INDEN eval again -- I'm still getting those errors : \