(ShareCast News) - BHP Billiton chairman Jac Nasser has announced his retirement from the board of the mining giant, which he delayed due to the Samarco dam disaster in Brazil.Speaking at the FTSE 100 group's annual shareholder meeting, which saw protests by Brazilians hit by the fatal disaster, Nasser said he would serve for one last year."Now that the basic structure of the Samarco response is in place, the findings of the expert panel have been published, the compensation and remediation programs have been initiated, and with BHP Billiton in robust shape, I have decided that I will not seek re-election at next year's AGM."Nasser also said even though a review of all tailings dams in the BHP portfolio confirmed that all were stable, further improvements have been made and a new standard has been created for its dams benchmarked against the Canadian Dam Association processes - the most rigorous in the industry.