A Simple Bug in NJOY2016 and NJOY2012

[jlconlin]

This was reported via email by Dr. Chikara Konno:

I found a bug in acefc.f90 of NJOY2012 and NJOY2016 (NJOY99 has no problem).

line 9683 in acefc.f90 of NJOY2012.50
line 9790 in acefc.f90 of NJOY2016.40

                       xss(next+1+nx+ix)=&
                         sigfig(renorm*xss(next+1+2*nx+ix),7,0)

is not correct. The correct one is the following.

                       xss(next+1+nx+ix)=&
                         sigfig(renorm*xss(next+1+nx+ix),7,0)

This bug is very simple, but it took one week to find this bug.

[jlconlin]

I have asked Dr. Konno to provide some documentation why the "correct" version is, correct.

[kahlerac]

All, I agree with this correction. I see it in NJOY99.0's src file and while it was corrected in 99.28 but somehow reappeared in the NJOY2012.0 src file. Sigh. Skip

…

On Fri, Sep 21, 2018 at 10:11 AM Jeremy Lloyd Conlin < ***@***.***> wrote: I have asked Dr. Konno to provide some documentation why the "correct" version is, correct. — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#105 (comment)>, or mute the thread <https://github.com/notifications/unsubscribe-auth/AQ6USc8wsc53aOxMSmITYSMY3efxlboIks5udPN0gaJpZM4W0O2n> .

-- Dr. A. C. (Skip) Kahler Kahler Nuclear Data Services, LLC [email protected] +1 321 368 3645

[jlconlin]

So this is an easy change to make, but how do we know it is doing the correct thing? It doesn't change any of the answers—at least not to a precision fo 1E-9.

[jlconlin]

@kahlerac pointed out that this only occurs for MF=6, LAW=7, laboratory angle-energy distribution. I went looking for this, but found no evaluations in ENDF/B-VIII.0 with these parameters. Two evaluations,

• H-2
• Be-9
  from JENDL 4.0 had these parameters.

I generated an ACE file from both of these files. I compared the ACE files produced before and after the fix and found no difference.

I would like to add a test demonstrating this, but haven't found something that can reproduce this error.