TITLE: Height one prime ideal of arithmetical rank greater than 1
QUESTION [5 upvotes]: Let $R$ be a Noetherian local domain which is not a UFD and let $P$ be a height one prime ideal of $R.$ Can we find an element $x\in P$ such that $P$ is the only minimal prime ideal containing $x$?

REPLY [4 votes]: I'll prove @messi's assertion that $R_\mathfrak{m}$, where $R=k[X,Y,U,V]/(XV-YU)$ and $\mathfrak{m}=(X,Y,U,V)/(XV-YU)$, is a counterexample to the question, that is, there exists $P$ a height one prime ideal of $R_\mathfrak{m}$ which is not generated up to radical by a single element. In other words, the arithmetical rank of $P$ is greater than $1$.
Let's write $R=k[x,y,u,v]$ with $xv=yu$. Then $R$ is a noetherian graded $k$-algebra with $\dim R=3$. Moreover, Proposition 14.5 from R. Fossum, The Divisor Class Group of a Krull Domain, tells us that $R$ is a Krull domain and its divisor class group $\operatorname{Cl}(R)$ is isomorphic to $\mathbb{Z}.$ Take $\mathfrak{p}=(x,y)$. It's easy to check that $\mathfrak{p}$ is a height one prime ideal of $R$ and from Fossum we also know that $[\mathfrak{p}]$, the class of $\mathfrak{p}$, generates $\operatorname{Cl}(R)$. Suppose that $\mathfrak{p}=\sqrt{aR}$. Since $aR$ is a divisorial ideal it follows that $aR=\mathfrak{p}^{(t)}$, $t\ge 1$. This implies that $[\mathfrak{p}]$ is a torsion element of $\operatorname{Cl}(R)$, a contradiction. Now we can pass from $R$ to $R_\mathfrak{m}$ by using Corollary 10.3 from the same book. 
Remark. In the view of curious' answer form this related topic, another way to solve this problem is to show that the local cohomology module $H_\mathfrak{p}^2(R)\neq 0$.