Encouraging the spread of nuclear technologies enables the spread of nuclear weapons

Nuclear weapons and nuclear power share a common technological basis. Skilled workers and continuing research are beneficial for both industries. The process of enriching uranium to make it into fuel for nuclear power stations can be a step towards further enriching it to make nuclear weapons. Used fuel (spent nuclear fuel) from nuclear power stations can be separated out to recover any usable elements such as uranium and plutonium through a method called reprocessing. Plutonium is a by-product of the nuclear fuel cycle and can also be used to make nuclear weapons.

Whilst the UK has enough plutonium to produce over 13,000 bombs from the civil stockpile alone, other countries now being encouraged to develop nuclear power may build-up reserves and use it for weapons at some future point.

The existence of nuclear power technology actually acts as a disincentive for the proliferation of nuclear weapons.

The Nuclear Non-Proliferation Treaty, whose signatories include every state in the world apart from India, Pakistan and Israel (plus North Korea and Iran who sign, then unsign, then sign again...), is largely a provision for the sharing of nuclear power technology, which it promises to share among members who do not produce nuclear weapons (or, in the case of the 5 nuclear states, who commit to a gradual and continual reduction in weapons stockpiles). This has seen states including Brazil and Argentina abandon their nuclear weapons programmes, in order to gain access to nuclear power technology.

The treaty also establishes and sets the remit of the International Atomic Energy Agency, which all members are bound to grant unlimited access to in order to facilitate inspection of nuclear facilities.

In such a way, nuclear energy is a tool by which global security is benefited.

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One definitely should learn more about nuclear weapons before relating it to nuclear powers. In an effort abolish nuclear weapon, in 2009, President Obama signed with Russia to reduce from 1700-2200 warheads in 2012 to 1500-1675 in 2016; from 1600 delivery vehicles in 2012 to 500-1000 in 2016. They focus on reducing delivery vehicles because they are faster to be get rid of and because they are the one and only tool to launch nuclear war. A warhead can kill no one without its vehicle with specifications. Therefore, as long as the number of delivery vehicles is reduced to minimum, there's no harm from nuclear warhead, let alone the nuclear power technology!