Radionuclide wise photon release rate after activation

riya · 29 July 2022 08:32

Continuing the discussion from Interpretation of results from activation simulation:

Just for future reference, I am attaching this journal paper. My intention was to explore if FLUKA can be used throughout the whole process mentioned in this attached journal (where they have used FLUKA for the first part and ORIGEN2 for the second part). I felt FLUKA could be more efficient tool for the second part also since it is already equipped with latest decay data and cross section data.

They have used ORIGEN and obtained the following result:

The main photon emitters are isotopes of W, Ta, Lu, Re, Yb and Hf, most of which have short half-lives and thus contribute little to photon emission after a comparatively long cooling time. For nuclides like 44Ti, 90Y, 157Tb, 94Nb, and their daughters, they contribute more than 90% to photon emission after a cooling time of 100 yrs, and the total photon release rate decreases about 5 orders of magnitude.

Hong_2016_Chinese_Phys._C_40_114102.pdf (981.3 KB)

Regards,

Riya

adonadon · 3 August 2022 15:36

Dear @riya,

Thank you for the paper and the information.
Did you try what I proposed to you in the previous thread?

Best,
André

riya · 8 August 2022 04:54

Dear @adonadon ,

Sorry for the delayed response. I tried to follow the 2nd method. Is this what you meant ?? Here I have put A and Z for Mo which emits beta (for testing the usrrnc).

usrrnc.f (1.2 KB)

adonadon · 12 August 2022 07:39

Dear @riya,

Yes, In that case you will ‘leave alive’ just those isotopes.
The contribution of any other isotope in the fluence calculation will not be considered.
I tried your code and it seems to be working fine for me, and you are doing correctly what I proposed to you. Very well done

Let me know if you have any further questions.

Cheers,
André

riya · 12 August 2022 09:10

Dear @adonadon ,

Thank you for confirming the routine. I have few questions regarding this routine.

I have considered neutron fission of nat U. In the output of RESNUCLE card, all the fission products and their decay products are printed. If I use usrrnc.f in the simulation where I have filtered out A and Z of Mo 99, I am getting the same RESNUCLE output. What I assumed was after using usrrnc.f, now only Mo 99 activity will be printed. Hence, in this regard, my doubt is that is this usrrnc.f routine is getting activated if I use USRBDX or USRTRACK or USRBIN corresponding to irradiation and decay time only ? Is it not associated with RESNUCLE output ?
Suppose, I want to get gamma for Tc 99m only. In that case, Z = 43, A = 99. What should I put for the meta stable state in usrrnc.f ? Does “IS” parameter play a role here ?
It will be helpful if you can direct me to the manual describing the various parameters in usrrnc.f to learn more about these parameters.

Regards,
Riya

adonadon · 15 August 2022 08:50

Dear @riya,

Yes, what you are assuming is correct, you should just get a peak in the RESNUCLE. It means that you are probably missing something in your input. Possibilities:

Are you using the USERWEIG card with USRRNC option?

https://flukafiles.web.cern.ch/manual/chapters/user_routines/user_routines/usrrnc.html?highlight=usrrnc

Are you compiling properly fluka with your routine?

Yes, you have to get the IS = 1 to obtain the Tc 99m.
It is in the link I added above

Best,
André

adonadon · 15 August 2022 08:58

Ok, I found the problem. Actually there is an error in your routine.

Try again using this routine modified

usrrnc.f (1.2 KB)

Cheers!
André

riya · 17 August 2022 03:52

Hi @adonadon ,

I have used the above routine. Can you please check if the USERWEIG setting is added properly ?

I have observed a few things:

With and without USRRNC.f, the Mo activity is different. Is it because if we use a filter of Mo at usrrnc.f, no other residual nuclide will produce ? What I assumed was the usrrnc only acts as a filter for printing the output. If it is not the case, then higher value of Mo activity without usrrnc.f is due to neutron fission of U235 as well as other pathway of Mo production (i.e. either radioactive decay of other fission products yielding to Mo 99 or neutron activation of other fission products yielding to Mo99). Using Mo 99 filter in usrrnc.f, it is actually stopping these other production pathways of Mo99 and only fission of u235 is happening. Is it the case here?
The error in activity is higher if usrrnc.f is used. Is there any reason for that? I have used same history in both the cases.
If I want to apply usrrnc.f to my USRBIN or USRTRACK or USRBDX output, should I use the same settings in USERWEIG ?? I have gone through the above link, but it was not very clear to me.
With usrrnc.f, why some radionuclides other than Z = 42 are getting printed in output ??

I am attaching the input files for your convenience. Also, I am attaching the two outputs with and with out usrrnc.f . Hope I have conveyed my doubts properly.

WithOUT_USRRNC

With_USRRNC

Mo_prod_ads_lv.inp (2.6 KB)
Mo_prod_ads_lv.flair (2.7 KB)
source_newgen_ads.f (18.7 KB)
usrrnc.f (1.2 KB)

Regards,

Riya

adonadon · 23 August 2022 08:51

Dear @riya,

Ok, I’ll reply first your questions and then I propose you a new option that I found:

Yes, You defined the USERWEIG properly
Yes, It is exactly what you are saying. There is another contribution that you are not considering due to the filter used in usrrnd.f
It is because you are reducing your statistics due to the reduction in the Mo yield from other pathways.
The USERWEIG does not change. It is ok in the way you defined it .
I do not get other radionuclides… or at least you should not if you applied the filter in the routine of A = 99 and Z = 42

Anyways, if you are interested in this routine, we can discuss it in another moment.
Now, in order to obtain the scoring that you are looking for, I realized that you could you the routine usrmed.f. I attach here an example for your case.
In the manual you can observe that if you want to call this routine you need to add a card called MAT-PROP. There, with the USERDIRE option you can call this routine. The routine will be called every time a particle is going to be transported in one of the materials defined in MAT-PROP.
Finally, what you will find in the usrmed routine:

the trackr.inc was included to the default usrmed routine. This was needed to be able to call the variable IAZTRK. This variable has the information of the radioactive isotope ( the A, Z and IS) that generated the particle currently transported.
Using the same logic of the options I proposed you in previous posts, if we are transporting a photon (IJ = 7) and A != 99 and Z != 42, then the weight is redefined to Zero ( WEE = 0).

What does it mean? It means that only the photons generated by A = 99 and Z =42 will be considered in your scoring

I hope It is a satisfactory solution to your problem.
As I said I attach the routine and the input file with the MAT-PROP card and a USRTRACK example to score the fluence.

usrmed.f (3.0 KB)
Mo_prod_ads_lv.inp (2.9 KB)
Mo_prod_ads_lv.flair (2.7 KB)

Cheers,
André

riya · 15 September 2022 10:47

Thank you @adonadon for the solution. I am sorry for my late response, somehow I missed the post.

Just to clarify few things:

Can you please explain “The routine will be called every time a particle is going to be transported in one of the materials defined in MAT-PROP”

For example, lets say I have two targets lets say target 1, target 2 . They are made of different materials (M1 and M2), but after neutron activation, both of them has produced Co 60 (lets say) along with other radionuclides. Now, in the usrmed.f routine, If I set IJ = 7 and A = 60, Z = 27, along with in the MATPROP, if I choose M1 only, then this routine will be active for M1 material (Target 1) only, right ? The other M2 material (Target 2) will not be affected by this. That is, in USRTRACK, I will get photon scoring from Co 60 generated in Target 1 as well as all other photons from other one or more radionuclides generated in Target 2. Is this how this routine works?

I have added a detector region at some distance from the Uranium where I wanted to score photons. Why there is 0 result in the detector region but there is output in Target region?

Mo_prod_ads_lv.flair (2.7 KB)
Mo_prod_ads_lv.inp (3.2 KB)
source_newgen_ads.f (18.7 KB)
usrmed.f (3.0 KB)

Regards,
Riya

adonadon · 22 September 2022 12:21

Dear @riya,

It means that when a particle is taken from the stack to be transported, if the particle is in a material specified in MAT-PROP, the routine usrmed will be called.

What you explain is correct, but in case you want to do the same for the material M2, you can extend the material in the MAT-PROP using WHAT(5), or adding a second MAT-PROP card.

In the routine, you are filtering photons generated from Mo-100. But, Mo-100 decays via double beta decay. Thus, you won’t get any photon from there. The scoring (USRTRACK) in the target comes from other electromagnetic processes, but none of them come from a gamma decay of an isotope.
Commonly used gamma-emitting isotopes - Wikipedia

Cheers,
André

riya · 22 September 2022 12:34

Hi @adonadon ,

I am filtering from Mo 99 (not Mo 100) which emits some gammas. (http://www.nucleide.org/DDEP_WG/Nuclides/Mo-99_tables.pdf) . Then I feel some scoring should be there at det region.

Regards,
Riya

adonadon · 22 September 2022 21:31

Hi @riya,

Ups, true. I was using an old routine filtering with A = 100. Sorry about that.

Yes, you are totally right. The problem is that the number photons reaching your detector is too low…
You can observe this in the following picture where 10000 primaries were used:

I consider that the question about the “wise” photon release is solved with the option of using the usrmed routine that I proposed to you above. The way to score properly these photons is a different problem that may deserve its own thread…

I recommend you to generate a new one in case that you still need more assistance.
Thanks.

To conclude, a few questions:

Is there a reason to use this detector?
I recommend you to add an extra MAT-PROP card in the inner void. Many decays are occurring in this region. Then, if you do not add this extra card, there will be photons from other isotopes that you are will not be filtering
After reading the paper, what it’s described there is totally different to this problem. What’s the connection between this problem and the one of paper? you are interested in doing this approach to this current problem or you would be interested in replicating the study of the paper using FLUKA instead of ORIGEN? (or maybe both )

Best,
André

riya · 23 September 2022 03:50

Thank you @adonadon for the detailed discussion. May I know how you have visualized the above image ? Have you used any specific scoring card whose output you have added in the layers option in the geometry viewer tab?

Also, I was wondering why is there some kind of bias of photons towards the inner void? The neutron source is at the center. Mo 99 is getting produced in the target. The decay of Mo 99 will produce some gammas which should move out from the target isotropically. From the image it seems there are more photons inside than outside.
From my understanding, this can be due to one of the two reasons.

Either the inner photons are from all the radionuclides produced after neutron activation which emit gammas (since I have not used MAT-PROP in the inner void, there no filtering is acting). Where as the outside photons are generating after applying the filtering in the target since I have used MAT_PROP there. Is this the case? [I think this is what you meant in the following comment

Or, the target is not uniformly irradiated by neutrons, the irradiation is more in the inner portion and less in the outside ???

One more query, suppose I want to employ MAT-PROP in the inside void, not the outside void. Is there any way to do it ? I mean since the material is same in both the regions, is there any way to choose one void region only ?

Now, regarding your questions,

I added the detector since the final goal is to estimate dose at 1 m distance from the target. If you see the paper, most of the time it is the intention in decommissioning study to get information regarding activation product in the reactor components and estimate dose at 1 m distance from it. So, I just added the detector (not in 1 m though) to check how many photons from that particular radionuclide will reach there which will contribute to dose (for example, ORIGEN tells what are the major gamma emitting radionuclides at various decay stages). So I was checking how many photons from Mo 99 are generating in target region and how many of them will reach to the detector region where I want to score dose at later stage…just to explore few things and make my concept clear before attempting the current problem as well as the study of the paper.

Regards,
Riya

fogallar · 5 October 2022 15:14

Dear @riya,

May I know how you have visualized the above image ?

This is a USERDUMP, take a look to the manual for details on how to use it. Its output can be visualized using the geometry tab of Flair in a similar way as an USRBIN, simply adding a Userdump instead of it.

Either the inner photons are from all the radionuclides produced after neutron activation which emit gammas (since I have not used MAT-PROP in the inner void, there no filtering is acting).

No, all photons are created in the target, so you do not need to filter anything in your void regions. They are all already affected by your filtering in the target material. This you can test very easily, set the weight of all photons to zero in your usrmed.f routine and keep only the MAT-PROP card for your target, then run your simulation and try to score photons (with USRBIN for instance). You will find out that you cannot, because you have killed all your photons.

Or, the target is not uniformly irradiated by neutrons, the irradiation is more in the inner portion and less in the outside ???

This you can find out by scoring neutron fluence using a USRBIN, in fact I would recommend you to always do so to cross-check your sources. But it is perfectly normal that you have more photons (and neutrons) inside the void region in your target. Your neutrons have very low energy so they will interact very easily with your material as soon as they go inside it, either to be captured or to scatter, likely back to your inner void, finding again your target on the other side of it. As result you have a higher neutron fluence in the inner parts of your U than in the outer. Therefore your photons will be more likely to be produced in the inner side of your U. Also, if they are emitted towards inside your target, they may scatter at the other side, maybe coming back inside (so one photon may be producing more than one line in Andre’s picture), while those that go outside never come back. This is why you see a higher track density in the inner void than in the outer.

suppose I want to employ MAT-PROP in the inside void, not the outside void. Is there any way to do it ?

As mentioned, you do not need to do so, but the easiest would be to discriminate between the different regions using the region number provided in the routine, which can be used to obtain the region name.

Hope this helps,
Francisco

riya · 6 October 2022 03:08

Thank you @fogallar for the suggestions and explanations. The topic is clear to me now.

Regards,
Riya