# Calculating Fissile Plutonium output to estimate nuclear capability of a country

1. Dec 7, 2007

### diabolic

Hi all,

I am just a mechanical engineer with no good background of nuclear physics. As I am doing some research on how much each country can posses nuclear bomb. The question is if I know the reactor location (approximate) , type of reactor and its Rated power (MWe) with assumed plant capacity factor of (75% for power mode & 80% for weapon grade mode) how can I calculate Spent (Uranium) Fuel / Yr (Kg) and Fissile Plutonium
output / Yr (Kg)

thanks,
Diabolic

2. Dec 8, 2007

### Astronuc

Staff Emeritus
The quantity of Pu produced depends on several factors: thermal power (roughly 3 times the GWe), mass of fuel in the reactor, irradiation time are principal, enrichment (fraction of U-235 and/or other fissile isotope), and the refueling schedule and batch size (number of fresh assemblies or fraction of core introduced during refueling).

The amount of Pu produced in nuclear fuel depends upon the conversion ratio (U-238 to Pu-239), which is a function of the burnup (GWd/tU, or MWd/kgU), and the mass of fuel in which the Pu is being produced.

3. Dec 8, 2007

### Dozent100

In a word, No! There are many, many other factors that determine product production. The Enrichment of the fuel, the flux density, The arrangement of the fuel and target material in the core. The free mean path of the neutrons. Fissile production requires very high flux density. To thermalize neutrons to produce weapons grade product, is not easy. In general, it is difficult to produce usable weapons grade material with a power reactor.
Any more than that, I would refer you texts on reactor design.

4. Dec 10, 2007

### diabolic

Thanks for ur inputs but I need to know how did the person in this paper calculate the fuel spent and plutonium yield.
http://www.indiaresearch.org/Indo-USStrategicDeal.pdf" [Broken]

Last edited by a moderator: May 3, 2017
5. Dec 10, 2007

### Dozent100

Actual Numbers

They could be actual production numbers? Note the wide range of the estimates!

Last edited by a moderator: May 3, 2017
6. Dec 10, 2007

### Astronuc

Staff Emeritus
I'm not sure how Sharma determined the yields, but perhaps it was based on knowledge of the discharge burnup and conversion ratio, and some knowledge of the fuel design. As Dozent100 noted, there is a range, and there is likely a wide band of uncertainty.

7. Dec 10, 2007

### diabolic

Sir,
When I try to emulate the same calculation I am not able to get the same numbers. For example Kaiga – 1 (PHWR) having power of 220 Mwe

Spent Fuel / Yr (Kg) = 220*3 (MWt)*1000 (for Kg) * 365 (days) * 0.75 (Plant capacity factor for power mode) /1.348 (U235 required / MWe-Year )

= 34638 kg/yr but the paper gives a value of 35,427 kg/yr

where am I going wrong? More over I could not get the logic he has used for calculating Fissile Plutonium output.

All I know is FAS (http://www.fas.org/nuke/intro/nuke/plutonium.htm") States, 1 megawatt-day (thermal energy release, not electricity output) of operation produces 1 gram of plutonium in any reactor using 20-percent or lower enriched uranium;

Wonder how he has used this data.

Dozent100, I do agree that it is just plutonium output and only a fraction of it will be converted into nuclear weapons. Still knowing these number will give approximate potential of that country. Plz tell ur opinion.

Last edited by a moderator: Apr 23, 2017
8. Dec 11, 2007

### Dozent100

Pu Production

There is a large difference between producing Plutonium and producing weapons grade plutonium. I won't go into those differences in an open forum because many are still classified. Of course, "Weapons grade" is only a desirable blend of Pu Isotopes, if you don't mind killing off your workers that have to handle the Pu to make a weapon.

I would point out that most of what you are trying to determine is in open literature. The real question is why do you need this data and what do you intend to do with it?

The answer has not changed: The Plutonium production in any particular reactor load, depends on may variables, including the isotopic make up of the fuel, and the target material; the core configuration; the moderator; The neutron darkness of the reactor internals, just to nane a few. You have to have a detailed knowledge of the physical design, metalurgical make-up of the core. Consider also the purity of the moderator, whether light water, heavy water, or something else.

I'll say it again, based on the information you have provided, The answer is not available. Trust me I used to do this for a living, including 5 years as an IAEA Safeguards Inspector.

9. Dec 12, 2007

### diabolic

thanks for ur candid reply. Surely the work will be killed when I am going nowhere

the answer is simple. The data I will be colleting is for self. When I stumbled accidentally pu on this link http://stinet.dtic.mil/cgi-bin/GetTRDoc?AD=ADA460305&Location=U2&doc=GetTRDoc.pdf" and when INDIA is signing a deal with US whated to study the effect of the deal with “deterrence postures” what to assess how much India is venerable and capability of china and Pakistan.

I do agree with all these things. For any outsider will also not know the answer for these. But still you could see people doing calculations for example so even I wanted to those calculations to get a feel

:-((

Last edited by a moderator: Apr 23, 2017
10. Dec 12, 2007

### Dozent100

The final word