A.H. Nayyar | Zia Mian


THE Pakistan Nuclear Regulatory Authority (PNRA) has finally cleared construction in Karachi of two large Chinese-supplied nuclear reactors. Approval of the Preliminary Safety Analysis Report (PSAR) submitted by the Pakistan Atomic Energy Commission (PAEC) was the final step required for building the K-2 and K-3 reactors. But this safety report, which is supposed to critically assess the safety of the reactor site, the reactor design, the management of the nuclear fuel, and possible accidents due to technical failure and human error and their consequences, is flawed in important ways.

This is not the first flawed official report on the new Karachi reactors’ safety and risk aspects. The Environmental Impact Assessment (EIA) report for the reactors was approved by the Sindh Environmental Protection Agency but was successfully challenged in the courts and had to be redone. Given the risks and possible catastrophic consequences, the PSAR should also be revised to address its flaws.

The first glaring error in the Karachi reactors safety report is its estimate of the number of people in Karachi, all of whom could be at risk in case of a severe nuclear accident. The city’s population is known to be in excess of 20 million already, yet the PSAR estimates Karachi will grow to only 14.5m people five years from now.

This is a serious mistake and one whose repercussions can get worse with time. The reactors are supposed to operate for 60 years and it is important to estimate accurately how many people will be at risk throughout these decades up to 2080. It is impossible to calculate accident consequences and make realistic plans for disaster management if you do not know how many people you have to deal with.

The report on nuclear reactors in Karachi ignores the risks posed by highly radioactive spent nuclear fuel.

Second, the safety report has looked only at a limited set of possible accidents involving the nuclear reactor. It has completely ignored the risks and consequences of a fire involving the very hot, highly radioactive spent nuclear fuel. The vulnerability of spent fuel was highlighted dramatically during the Fukushima nuclear disaster in Japan in 2011, where an explosion completely ripped apart the spent fuel pool building and only good fortune stopped a massive release of radioactivity.

Spent fuel pools pose grave risks because they are meant to contain the multiple loads of radioactive fuel that are discharged from a reactor over many years. The actual reactor core only contains one fuel load at a time. Once the nuclear fuel has been used in the reactor, it is taken out and stored underwater in a pool close to the reactor building. The pool needs to have a continuous flow of water to keep the hot spent fuel cooled. If for any reason the cooling water leaks out or evaporates, the hot spent fuel can react with the air and cause explosions and fires and release its radioactivity.

The two new Karachi reactors will share a spent fuel pool. The design storage capacity of the planned pool is 18 years, while the reactors are expected to operate for 60 years. Unlike the nuclear reactor fuel core, which sits inside a strong steel shell and a thick double-walled concrete containment building, the spent fuel pool is not well protected against an accident or against an outside attack.

Since the Fukushima accident, there has been growing concern about spent fuel pool safety. Soon after the disaster, the US Nuclear Regulatory Commission launched a study of the dangers from spent fuel pool fires. It found that a spent fuel pool fire could lead to over three million people being relocated from an area of almost 12,000 square miles (over 30,000 square kilometres).

In May 2016, the United States National Academy of Sciences released the second part of a major study, Lessons Learned from the Fukushima Nuclear Accident for Improving Safety and Security of U.S. Nuclear Plants: Phase 2. This looked specifically at the danger from spent fuel and found that existing safety assessments of spent fuel fire risks in the US were inadequate, noting in particular that there were problems with the computer models that were used. It called for a better understanding of how spent fuel pools react to a loss of water in case of accident or attack and better planning for what to do if this happened. It confirmed that “a spent fuel pool accident can result in large radioactive material releases, extensive land contamination, and large-scale population dislocations”.

Also read: The Nuclear Shadow over Karachi

The PAEC is aware of some of these risks. The EIA report for the new Karachi reactors says: “The worst case scenario during storage is that the water of spent fuel pool is lost when the freshly released fuel is stored in the spent fuel bay. This may result in loss of shielding and cooling of the fuel.” It notes that this “loss of cooling can be due to pipe rupture used to transport cooling water to the spent fuel or the pump failures”, or a “crack in the spent fuel pool”. Yet the safety report does not discuss the consequences of an accident or a terrorist attack causing such a failure of cooling.

The purpose of a nuclear safety assessment report must be to consider the possibility of the worst conceivable accident at the reactor and its related facilities, and the impact of such an accident on people and the environment. The Chernobyl accident of 1986 showed that these impacts can extend over many hundreds of kilometres and last for decades. Fukushima showed that it is not just the reactor that is a hazard.

The limited scope and shortcomings of the PSAR for the new Karachi nuclear reactors adds to other fears that have been already raised about these plants. The PNRA needs to take more seriously its obligation in law to ensure the safety of the public and the environment from nuclear activities that it licenses. It is not too late to start.

The writers are physicists with an interest in nuclear issues. 

Published in Dawn, August 13th, 2016.