Nuclear power (and plutonium in particular) is a symbol of war.
That is a rather shallow argument. People always associate things with other things, frequently by the most tenuous of connections. The consistent attempts by the opposition to link the peaceful use of nuclear power to nuclear weapons is an attempt to poison the well in the debate by creating the straw man that supporting nuclear power is also be a war-mongering supporter of weapons of mass destruction. It is pure emotional dogma and an example of the fallacy of guilt by association.
From an industry perspective, it could be argued that nuclear weapons are a waste of perfectly good fissile material.
The nuclear fuel cycle can be abused for the purpose of producing nuclear weapons.
Countries with nuclear weapons saw no need to abuse civil facilities for this purpose. They created infrastructure dedicated to producing nuclear weapons, using its own fuel and technology. Given the unique set of requirements, the different technology and the working culture, this makes far more sense. Any continual build up of nuclear arms in the nuclear weapons states will be irrespective of the use of civil nuclear energy.
For those that might want to undertake a nuclear weapons program using civil facilities, they have to get past the International Atomic Energy Agency. Under the mandate of the Non-Proliferation Treaty, they undertake routine inspection of all nuclear facilities in NPT member states to ensure there is no diversion of materials from the declared and proper, peaceful uses.
The NPT has been signed by 187 countries, including the five declared nuclear weapons states (USA, UK, France, Russia and China). All states agree to proper declaring of all transactions and movement of nuclear material and inspection by the IAEA to verify the documentation. For non-weapons states, this applies to all nuclear facilities, while for the five weapons states it applies only to specific sites declared for civilian purposes. States that do not sign the NPT are barred from the international nuclear market and signatory states that do not comply face diplomatic and economic action or worse. The two current uranium giants, Canada and Australia, take precautions in their sale of uranium to ensure it will only be used for peaceful purposes.
Among the vast majority of signatory nations, this has proven a success at deterring such diversions and nations such as South Africa have explicitly renounced their nuclear weapons programs in order to be able to trade in nuclear commodities with the rest of the world and benefit from the peaceful use of nuclear energy.
Reprocessing of nuclear wastes can be used to extract bomb grade plutonium.
Ignoring of course IAEA safeguards, that is only possible if bomb grade plutonium is produced in the fuel in the first place. Weapons grade plutonium is produced in specially designed reactors because of the technical precision required to ensure the purity of plutonium-239. Plutonium produced inside power reactors is full of plutonium-240 and plutonium-241 and others totalling at least 45% of the element. These isotopes sometimes undergo spontaneous fission and this tends to lead to pre-ignition, whereby the bomb blows itself apart before a significant amount of energy is released. No plutonium bomb has ever been produced with less than 90% plutonium-239 in it.
The proliferation threat is not reprocessing, but production of weapons grade material in a reactor in the first place. This does not happen in commercial reactors.
Non NPT states like India, Pakistan and Israel have developed nuclear weapons and NPT states like North Korea and Iran continue to try. Surely our use of nuclear power sends a bad example to these countries.
It could easily be argued that having a non-proliferation treaty that legally allows a select five nations to retain nuclear weapons is sending a bad example to those countries as we try to negotiate for their disarmament. However, the use of civil nuclear power has nothing to do with it. At no point is it said that they cannot have nuclear power, just not nuclear weapons. In fact, the US was prepared to give a light water reactor to Iran in return to suspending their enrichment efforts, which they are not opening to proper safeguards. If these countries all signed up and complied fully with the NPT, allowing regular IAEA inspection and vetting as all other civil facilities are subject to, there would be no problem whatsoever with these countries having nuclear power.
The concept of giving up some aspect of nuclear power to set an example to would be nuclear pariahs has been tried before. In 1977, President Carter banned all reprocessing of civil spent fuel in the US in an attempt to encourage others to do the same, thereby eliminating the possibility of nuclear weapons proliferation, which is specious in any case, because reprocessing cannot be used to extract weapons grade material if there is none to extract. This was a spectacular failure. No other country followed suit and the rogue states, which wanted nuclear weapons, continued to try to develop them.
The assertion that we should give up nuclear power to encourage states like North Korea to stop developing nuclear weapons is not only futile, but also rather arrogant and egocentric.
If we put an end to nuclear activities then we should be able to erase the knowledge that will allow the development of nuclear weapons.
How Orwellian! No doubt some of the more authoritarian anti-nuclear types will approve of this idea, but many more will have some aversion to the idea that inconvenient or unpleasant knowledge should be purged from human consciousness, with all requisite burning of books and cleansing of the population.
More to point, this is entirely unworkable. Knowledge is not so easily compartmentalised. The basic physics that allowed the development of nuclear weapons has applications everywhere and so there is no way to just delete it. Further to that, the first bomb makers developed their knowledge from scratch. It has been done before and it can be done again. Attempting to pretend Einstein and Rutherford never existed will never succeed in actually eliminating knowledge.
The genie is out of the bottle and it is not going back.