The Nuclear Security Summit in Seoul kicked off in full force Monday as 57 world leaders assessed past achievements in global nuclear security and seek more concrete global action.

The working dinner followed a two-hour welcome reception by South Korean President Lee Myung-bak, who plays host to the two- day summit that is a sequel to the inaugural 2010 Washington summit where U.S. President Obama set the goal of securing the world's loose nuclear materials by 2014.

"We have achieved a lot at the Washington summit two years ago. Based on the achievements, I hope we will achieve another success at the Seoul summit," Lee said in opening remarks, according to a pool report.

The leaders shared measures individual countries have taken to meet the goals specified in the Washington communique, including eliminating and minimizing nuclear materials and joining and ratifying global accords on nuclear security.

The 47 countries that joined the 2010 summit have completed 80 percent of their individual pledges, including domestic legislation and participation in global nuclear security forums.

Thirteen leaders who presented their achievements to others at the table said bolstering nuclear security and preventing nuclear terrorist attacks are on the top of their national agenda, according to a spokesman for the summit.

"The results of the Working Dinner revealed that there had been substantial progress since 2010," the preparatory secretariat said in a press release. "(It demonstrated) that the Nuclear Security Summit process is indeed contributing to strengthening nuclear security based on a shared understanding of the danger of the threat of nuclear terrorism."

On Tuesday, the participants will join plenary sessions and working lunch before President Lee Myung-bak will hold a press conference showcasing highlights of the summit.

The Seoul communique is expected to reaffirm commitments to minimizing the use of highly-enriched uranium and plutonium and expand discussions on nuclear safety in the context of nuclear security following the nuclear crisis in Japan.