I'm surprised the old fuel is placed at the rim. The neutron flux should be less out there. I would think placing fresh fuel at the edge would minimize the difference in energy output from the center out to the edge. I've heard hot spots are a problem. Doesn't putting fresh fuel at the center...
I associate transmutation with a change of element, not just a new isotope of the same element. Is there a special verb for that? “The neutron plumps the 235-U nucleus if it doesn’t cause fission…”
I didn’t specify stable, so your lambda+ term will help. This is in reference to my nuclear...
Given an initial mass of some isotope subjected to a constant neutron flux, how fast will the mass drop off? Would not the survival curve look exactly like the curve for radioactive decay? Both cases describe a starting mass subjected to a constant transformative force at a rate that depends...
Indeed, extraction of the fission products is another facet of MSR operation that I need to handle. Like neutron absorption, I'm putting that off until I nail down a simple decay-only methodology.
I have data for the rarer and short-lived isotopes. Removing them is slightly error-prone. The...
I'm thinking that the problem is a lot simpler if the fuel isn't fixed in place. How much of ORIGEN's code is devoted to the composition of each fuel pellet, which stays in place for ~18 months? How much sim time is devoted to rearranging half-used fuel bundles in different configurations at...
I 'm not ignoring decay chains. I just haven't gotten to them yet. And I'll handle absorption after that. I'm trying to separate the problem of tracking cumulative yields into manageable pieces. To put this in context, I am trying to simulate the isotopic composition of the salt in a molten...
OK. Without transmutation, and with no contributions from decaying parents, what is the estimate for cumulative yield with respect to initial yield for an isotope that has reached equilibrium?
I can’t find yield data for the concurrent creation and decay of fission products in an operating reactor. All the references I can find on the net are for the decay of a fixed lump. In an operating reactor the lump is (for a while) growing at the same time it is decaying. So, I started my...
To mathman, re http://atom.kaeri.re.kr/ton/
(This forum doesn't indent enough!)
Yes I visited the Korean site, twice. On my second visit I followed one reference URL back to a UK paper on PDF at Brookhaven. A bit roundabout, but very worldly. The PDF topic is not really half-lives, but they...
Sorry. I do mean the first excited state. None of the isotopes on my list show up on the list you provided.
These aren't exactly rare fission products. The max yield for 109-Ru-m1 is over 1%, albeit for 142-Am-m1 as the fuel. For 85-Se-m1 it's ~0.5% for 233-U and 235-U. I expect they aren't...
The Sigma database at Brookhaven lists seven isotopes as fission products for which I can't find half-life data. I've tried nea6287-JEFF-20-1, the NuDat_2 web site, Nuclear Wallet Cards and Wikipedia. Anybody have any other ideas?
The isotopes are
74-As-m1
85-Se-m1
86-Br-m1
109-Ru-m1...
The collection point in the MSRE was the fuel input tank. It was partially filled with helium. They bubbled helium gas up through the fuel and this helped carry about 5/6ths of the xenon away. This paper from 1969 mentions that, and some of the research requirements for future MSR development...
For a fast, solid fuel reactor, probably. This thread is about LFTR, a thermal liquid fueled reactor. There are fast liquid fueled reactor designs. Gaseous fission products bubble out of the liquid for either. Not a pressure problem, but piping the gasses off elsewhere has a number of other...
Thanks. I didn't know the 14MeV data was for fusion. This simplifies things. I would use just two bins, fast and slow. The user would have some design in mind, and possibly some high-powered sims to estimate the energy distribution. That estimate would, with some more work, yield two...