Is it possible to experience powerful sensations, such as orgasm, without getting attached to it?

If all humans relize the ultimatos truth, "that all Beings be happy" all human race will go to an end passing less than 200 years. All humans produce dopamine but is a litle different to be addicted to This às a drug. Barry komisaruk can explain what are o*g**ms, non genital o*g**ms exist naturaly, just google it. While meditating you can gett o*g**m and sleping. even if you have your reproductive organs totally inactive you should be atracted to the other may be.

Here is the thing about Sexual activities....

We do not admire it like the western culture,But the eight fold path is not a hammer on your marriage life.You can still have sex but with her only. And if you are single there is a set of guidelines established din Buddhism in finding the correct type for sex (Please refer a good source about Five precepts).

You can very well feel anything without getting attached to it,

How do i know it?

well arahants still felt the heat,coldness,soft touch of clothes,the comfort of a breezing wind,the beauty of a jungle.But still they had no disturbance from it they even admired the beauty of nature.

But in the examples you are presenting in your question we can't agree that it can be felt without the addiction to it. Basically the main reason for sex is the attachment that you have for it.

Sex is not a huge deal for a beginner but alcohol is an addiction with no virtual benefit,it is that simple and under n o circumstances can be justified as something a Buddhist would do. You can have some help from meditation to fight the urge to drink and some therapy or rehab would also help.that is something you will have to fight on your own.

Remember what Lord Buddha said

This is an individual's fight against himself,in it he will need good friends,Knowledge of dharma and courage.But he must fight alone.

Well we are here to help so start with one day without alcohol and let's see what happens from there.

According to Alagaddupama Sutta, it isn't possible:

For a person to indulge in sensual pleasures without sensual passion, without sensual perception, without sensual thinking: That isn't possible.

The commentary makes it more precise:

According to the Commentary, "indulge in sensual pleasures" here means indulging in sexual intercourse; the Sub-commentary adds that other acts expressing sexual desire — such as hugging and petting — should be included under this phrase as well.

To experience an o*g**m you need some form of active arousal. If arousal is involved you are attached and goes against the precept.

If it is from other causes like bed wetting then it may be OK as long as you don't fantasise. If there is fantasy then again there is attachment.

Main thing to remember is sensation is involuntary sometimes but seeking sensations is not without attachments, and seeking sensations can be very subtle.

Does the Buddhist breathe? Does the Buddhist drink water? Does the Buddhist eat food? Does the Buddhist exercise?

If all of these needs can be met without attachment, why should sex be any different?

Sex can be entirely to meet one's biological urges, the way we eat and drink and exercise. I'm not saying it is easy to do so, but it seems to me that clearly the possibility exists.

No. All healthy humans are biologically addicted to dopamine. "The brain includes several distinct dopamine systems, one of which plays a major role in reward-motivated behavior. Most types of reward increase the level of dopamine in the brain, and a variety of addictive drugs increase dopamine neuronal activity."

Dopamine is the hormone that makes you feel good. If you can o*g**m without it feeling good then, yes. You can never feel anything good without attachment. Humans are hardwired to like dope just as they do sugar and for the same reason; need. The need to procreate the species and the need to consume calories.

I have experienced ejaculation without it feeling "pleasant". When ejaculation does not feel pleasant, it feels more like semi-painful spasms. There is no attachment to this experience.

It is not that ejaculation has changed, or even that the experience changed. It is my perspective that has changed. If you look at pleasant sensation very very very carefully, then you will see it as is -- and it will loose it's luster.

The same with pain, if you look at it really close, you will see it as information. No pain, just information.

As Buddha taught, we must learn to see pleasant in non-pleasant and non-pleasant in pleasant. When we can arbitrarily control our evaluation of sensory experience, then we are free from it.