Comments on: Good news of 2011 in review

By: Johan Simu

Johan Simu — Mon, 30 Jan 2012 15:00:00 +0000

Interesting if one could get around the 10 limit by just placing several reactors in the same building

I hope the whole reactor counting and the restriction of only building new reactors at existing sites will get ditched. I think (hope) industry would be interested in building their own small reactors if they had the chance.

By: Johan Edlund

Johan Edlund — Fri, 27 Jan 2012 00:10:00 +0000

Clearly the law was not written with modular reactors in mind but swedish law seems to define a "nuclear reactor" as a "plant for the extraction of nuclear energy" with no regard to how many pressure vessels or separate cores that are allowed within that plant. At least I can't find anything that clearly outlaw such a design. In the end a PRISM plant with six reactors would produce about as much energy as a single large LWR. A bigger issue appears to be with the licensing catch 22 these reactors are suffering from. Regulators have no interrest in licensing new reactor designs unless they have a customer in mind for that particular design. The electric companies on the other hand have little interrest in reactor designs that don't have some sort of approval from the regulator before they order one, this is understandable since delays can get very expensive. With the PRISM, it has at least got a pre-approval by the NRC back in 1994.

By: Johan Simu

Johan Simu — Tue, 24 Jan 2012 09:03:00 +0000

I think the 10 reactor limit will sabotage any ambition to build a PRISM in Sweden. Its written quite explicitly, for the same reason I don't think small modular LWR's has any hope in this country even though they make a lot of sense technically. But even if one could count several PRISM's as one reactor I doubt a swedish utility would buy it even if it is the same cost per installed watt. The nuclear industry and the regulartory authroity are so conservative that they would probably not bother learning sodium technology and instead go for what they know best. May be a pessimistic outlook but I'm afraid its like that

I really hope UK goes for the PRISM!I read the paper from ther german about pebble bed. I don't remember the content anymore but me and all my collegues at the time all agreed that it feelt like the guy was really reaching very hard to find negatives. He has some points, due to the random packing of the pebbles hot spots can appear etc. But with modern analysis methods one can introduce such hot spots in the simulations and make sure they never go above the max temperature. But even if one had a multiple of hot spots, say after a eart quake compacting the ore, the fission product release would still be insignificant compared to the meltdown of a LWR.

The dust is certainly an issue as well, I wonder how the chinese has solved it. Otherwise one can always go with the GA prismatic block design that avoids that issue, at the cost of less flexible fuel cycle of course.

By: Johan Edlund

Johan Edlund — Mon, 23 Jan 2012 10:39:00 +0000

UK got the worlds largest civilian stockpile of plutonium and they have to deal with that somehow. For now they really only got two options; build a new MOX fuel plant and use it in LWR's or go with the PRISM reactor. AREVA have lobbied for the MOX plant as the only option until GE-Hitachi offered PRISM as an option. The PRISM reactor offer would not include a reprocessing plant (although one could be added later) but would be a once through cycle, the advantage being that PRISM uses metallic fuel and so would not require a MOX fuel plant. The used PRISM fuel can then be stored along with regular used LWR fuel.
　
As for the PRISM as a potential candidate in Sweden I would guess that its cost vs. the cost of LWR's is what will decide, if a new plant gets the go ahead. One can wonder though, how the six reactor PRISM plant will work with the ten reactor limit we have in Sweden today? Will one block they be seen as one reactor or six?
　
A predecessor to the PRISM, the EBR-II, was during the eighties shown to offer similar passive safety as a pebble bed reactor. With the reactor at full power and the safety systems disabled the coolant pumps were stopped and as the reactor temperature rose, the reactor output dropped until it reached zero.

As for the pebble bed reactor, a while ago I read a german report regarding their safety. Apprently they are not as safe as often suggested. Temperatures in the core have on occation exceeded maximum levels and contamination of the primary cooling loop by fission products and graphite dust were among the problems mentioned. The latter make the plant difficult to service and the fission products could possibly escape in case of a leak.

By: Johan Simu

Johan Simu — Wed, 18 Jan 2012 19:33:00 +0000

That we will!

By: Anonymous

Anonymous — Sun, 15 Jan 2012 13:56:00 +0000

The big relief is that the Germany panic only spread to Italy. Poland is still going ahead with their (rather ambitious) plans, the Soviets where kind enough to point out good locations for nuclear plants so the sites are already there.

The conspicious nondebate in Sweden is worrying. It would seem that there are a few loud voices against nuclear power, but it would seem poeple in general would rather have the plants up and running (they even get upset when they are NOT running). Even the Danes (who are partially responsible for the shut down of two reactors) seem to be regretting their hasty diplomacy...

We shall see what the future brings, eh?!