No they don't. Why would they want this radioactive toxic dumpster fire as their full responsibility? They're much better it being within their sphere of influence - so that anybody who wants anything done has to deal with China and make suitable offers to get things done - while having pretty much zero responsibility for the welfare of the people and not being subject of criticism for any atrocities that happen there, and not granting the people there even minuscule rights that Chinese subjects have. Current situation - at least until it explodes into a hot war - is a huge win for China, they are indispensable as the only power capable of putting a leash on Crazy Kim, they look relatively good in comparison to him, and they don't have to spend anything on it or bear any responsibility.