The attacks by the United States and Israel on Iran’s nuclear sites mark the first time any country’s operational nuclear facilities have been targeted to destroy them. As a result, numerous concerns have emerged in the aftermath of the attacks, including the risk of radiation leaks.While Iran and the International Atomic Energy Agency (IAEA), the global nuclear watchdog, have reported no increase in radiation levels so far, other worries persist. These include concerns about the safety and whereabouts of nuclear material stored at the targeted facilities — Natanz, Isfahan and Fordow.The attacks could also disrupt IAEA’s access to these nuclear sites which has till now helped the organisation, and the rest of the world, gather information about the goings-on at the facilities.Assessing risk of radiationThis is a relatively easy exercise. Every nuclear facility, anywhere in the world, is fitted with instruments that monitor radiation levels in real time. In most cases, the data are shared with the IAEA.Also Read | Iran fires missiles at US air bases in Qatar, explosions heard in DohaIran is a signatory to the Nuclear Non-Proliferation Treaty (NPT) as a non-nuclear weapon state. In that capacity, it had to mandatorily enter into a comprehensive safeguards agreement with the IAEA, which allows the organisation to install its own equipment to monitor activities, including radiation levels.Bigger radiation leaks can even be detected from far away. Nuclear radiation typically consists of alpha, beta, and gamma rays, and neutrons.Of these, gamma rays can travel long distances, and can potentially be detected by sensors in other countries. In certain cases, signatures of a leak can be captured by satellites as well, though not in real time.Ascertaining a radiation leak is not very difficult. That is why the IAEA was able to put out a statement within a few hours of the attacks on Sunday, declaring that it had not noticed any increase in radiation levels around the facilities.Assessing damage to facilitiesStory continues below this adThe damage to Iran’s nuclear sites is still being assessed as most of their crucial parts are underground. The Fordow facility, used for enriching uranium, is almost entirely underground; most of the Natanz facility, including the enrichment infrastructure, is underground; while some parts of Isfahan are also apparently underground.Also Read | Trump announces Iran-Israel ceasefire: Why Tehran gave ‘early notice’ of its attack on US base in QatarWhile Iran has played down the impact of the attacks, saying no irreversible damage has taken place, IAEA’s preliminary assessment presents a more serious picture. IAEA Director General Rafael Mariano Grossi, in his opening remarks at the emergency meeting of the IAEA Board of Governors, called to discuss the situation in Iran, said that the fuel enrichment plant at Natanz had been hit.At Fordow, craters could be seen, but the damage underground could not be assessed. At the Isfahan site, buildings, including some related to the uranium conversion process, and entrances of the tunnels leading to halls meant for storing enriched uranium, appear to have been it, Grossi said.Although the IAEA has its team deployed in Iran, the organisation does not currently have access to the attacked sites. The IAEA has said its staff is ready to carry out inspections of the sites to assess the damage, but their safety might be a concern in the current situation.Accounting for n-materialStory continues below this adThis might be the biggest concern right now. The IAEA keeps track of all nuclear material around the world with the help of information provided by host countries. Every country using, storing, or handling nuclear material is supposed to report its status to the IAEA. This is particularly true of countries such as Iran, which, besides being an NPT signatory, is also under special watch due to its suspected attempts to build nuclear weapons.According to the IAEA, Iran has 400 kg of uranium that is already enriched to 60%, just a few steps away from further enrichment to weapons-grade level of 90% or more. The total stockpile of uranium and other nuclear material would be much more. Much of these nuclear materials were believed to have been stored at the sites that have been attacked.Iran has said that anticipating the attacks, it had already evacuated its sensitive nuclear materials from these facilities, and moved them to undisclosed safer locations.There have been reports of a long line of vehicles seen in some pre-attack satellite images at the Fordow site, suggesting that nuclear material may indeed have been moved. The absence of any radiation leaks from the attacked sites could support this argument.Story continues below this adThe attacks by Israel and the US could make it difficult for the IAEA to fully account for all the known nuclear material in subsequent inspections. This might lead to the unverified use of nuclear material or nuclear proliferation.