Convert BROND-3.1 Be-9 ace-to-hdf5 Error

User Support
1

I was trying to convert Be-9.ace data with the openmc-ace-to-hdf5 command.

$ openmc-ace-to-hdf5 tape26
Failed to convert 4009.00c: Unsupported ACE secondary energy distribution law 67

First, I’ve converted the 4-Be-9.dat ENDF file into an ACE file with the help of njoy21. I’ve attached all my input files in a zip file.

Njoy Input file

moder
20 -21/
reconr
-21 -22/
'ENDF/BROND-3.1 PENDF for   4-Be-9 '/
425 3 /
.005 /
'ENDF/BROND-3.1 PENDF for   4-Be-9 '/
'processed by the njoy nuclear data processing system' /
'see original BROND-3.1 tape for details of evaluation' /
0 /
broadr
-21 -22 -23/
425 1 0 1 0 /
.005 /
300./
0 /
heatr
-21 -23 -24/
425/
moder
-24 28/
groupr
-21 -24 0 -25/
425 3 2 9 0 1 1 1 /
'ENDF/BROND-3.1 PENDF for   4-Be-9 '/
300./
1.0e10/
16 /
0 /
0 /
acer
-21 -24 -25 26 27 /
1/
'From njoy test problem 7'/
425 300. /
0/
/
stop

Download link: 4-Be-9.dat

My first attempt was

import openmc.data

d = openmc.data.njoy.make_ace('4-Be-9.dat', stdout=True, njoy_exec='njoy21')

Error

UnicodeDecodeError: 'utf-8' codec can't decode byte 0x92 in position 1448: invalid start byte

I’ve no idea how to fix this error.

Thanks in advance!

2

Unfortunately, some ENDF evaluations are not properly formatted. The ENDF-6 format requires files to contain only ASCII characters. It appears that this file has a non-ASCII character that is causing problems. You can make the following change to fix it:

119c119
< channels are characterized by the following MT�s:                  425 1451  118
---
> channels are characterized by the following MT's:                  425 1451  118

Once I made that fix, I was able to generate an ACE file and convert it to HDF5. I wasn’t able to reproduce the error you saw about the unsupported ACE law.

3

Sorry for the late reply here @paulromano

I saw similar error Failed to convert 4009.00c: Unsupported ACE secondary energy distribution law 67 with

isotopes and U-235 with

 ***error in findf*** mat9228 mf14 mt 51 not on tape  12

error while running njoy21.

4

Can you paste the output you see from the ACER module in NJOY? The “new formats” flag should be set to 1 by default which will avoid the use of the older secondary energy distribution format that is not supported in OpenMC. If I change that flag to 0 instead of 1, I do see this same error, but that should not be the default behavior.

5

@paulromano I’ve included all my input-output files in a zip file.

output file drive link

6

In your NJOY input on the fifth line below acer, you have:

0/

This will cause NJOY to use the older format (law 67) for secondary angle-energy distributions if they are present in an evaluation rather than the newer format (law 61). If you just change that line to:

/

It should produce an ACE file that OpenMC is able to handle.

7

Thanks @paulromano.

And what’s wrong with the U-235

Could you kindly explain it?

8

@Pranto This error is from NJOY, not OpenMC. Here’s the relevant section of the NJOY manual that mentions this error:

9

Thanks @paulromano :slight_smile: