@oralloy,
LWR's have been around forever. A recent study found that they are not as much of a proliferation deterrent as once thought because of advancement in ways to make reprocessing plants.
'Conclusions
The Light Water Reactor (LWR), the standard power source for most nuclear power stations around the world and the likely design for future ones, is not nearly so "proliferation resistant" as it has been widely advertised to be. From a proliferation point of view the LWR is generally preferable to other types of power reactors but the differences are more blurred than was previously appreciated.
With today's technology small, difficult to find, clandestine enrichment facilities or reprocessing plants could provide the reactor's owners with militarily significant quantities of nuclear explosives.
We need therefore to revise the conventional wisdom that LWRs are a safe proposition for siting in just about any country so long as there are no accompanying commercial uranium enrichment facilities or reprocessing facilities.
The principal "front end" concern relates to gas centrifuge enrichment plants. . It is now widely understood that even if such plants are safeguarded and designed to produce low enriched uranium (LEU) for LWR fuel, their owners could convert them quickly to produce highly enriched uranium (HEU) for bombs. It is less appreciated that if the owners divert some of the LEU produced by the declared plant and used as feed for a clandestine enrichment plant, they can reduce the needed plant capacity by a factor of five. Moreover, such LEU feed need not rely on the existence of an LEU plant; it could come from processing the fuel pellets of a fresh LWR fuel reload. The possibility of using centrifuges to produce HEU for bombs has been enhanced by recent revelations regarding Pakistan's spread of this technology to Iran, Libya, and North Korea, and possibly others, with the fabrication of parts in a number of other countries.
It is also widely understood that reprocessing plants that separate plutonium from LWR spent fuel for later use as fuel could also provide plutonium for bombs. What is less understood, and emphasized in this report, is that small, clandestine reprocessing plants could provide the reactor's owners with militarily significant quantities of nuclear explosives. Such technology is well within the capabilities of countries like North Korea or Iran.
Clandestine reprocessing is only half of the plutonium concern. The other is that contrary to conventional wisdom LWRs can be copious sources of near-weapons grade plutonium that can be used to make powerful nuclear weapons. The widely debated issue of the usability for weapons of plutonium from LWR fuel irradiated to its commercial limit has diverted attention from the capacity of an LWR to produce large quantities of near-weapons grade plutonium from partially irradiated spent fuel. The characteristics of bombs based on this material would not be significantly different than those based on weapons grade plutonium.'
http://npolicy.org/article.php?aid=172
