REPLY BY MINISTER FOR DEFENCE TEO CHEE HEAN TO PARLIAMENTARY QUESTION ON THE REPORTED LEAK OF RADIOACTIVE WATER BY THE USS HOUSTON WHEN IT CALLED AT SINGAPORE IN SEPTEMBER 2006

On 1 August 2008, the media reported that the US nuclear-powered submarine USS Houston had been found to be leaking trace amounts of radioactive water. The leak had been discovered by the United States Navy during a routine dry dock maintenance of the submarine at Pearl Harbour Naval Shipyard in July 2008. The media noted that the US had informed Japan of the leak, as the United States Navy's investigations had determined that the USS Houston could have been leaking when the USS Houston made its port call in Sasebo, Japan in March 2008.

At that time, there was no information to suggest that the leak went beyond the port visit that the USS Houston had made in Sasebo, Japan. Nevertheless, as a precautionary measure, we had asked the US on 4 August 2008 for information about the leak. The USS Houston had last called at Singapore nearly two years ago from 22 to 26 September 2006. We also went through our own monitoring records for the period when the USS Houston was berthed in Singapore at Changi Naval Base.

On 7 August 2008, the US informed MINDEF that the USS Houston had been leaking trace amounts of radioactive water since June 2006. This suggested that the USS Houston could have been leaking during her port call at Changi Naval Base in September 2006. During this period, the USS Houston had also called on other ports in the region including Japan, Malaysia, and Guam.

The US has assessed that the cumulative amount of radioactivity that could have been leaked in Changi Naval Base was approximately 0.095 micro curies. To put things into perspective, the US indicated that this was less than the amount of radioactivity found in a common smoke detector, and would not have any adverse effect on human health, marine life or the environment.

Apart from the information provided to us by the US, MINDEF has its own independent monitoring system. Since February 2003, MINDEF has put in place a round-the-clock Integrated Environment Monitoring System (IEMS) at Changi Naval Base. The IEMS takes readings of air quality, and water and sea-bed samples to determine the normal background environmental radiation level, and to detect whether there has been any abnormal level of radiation which may be of safety concern. The safety limits are set by our National Environment Agency's Centre of Radiation Protection and Nuclear Science.

While the USS Houston was in Singapore in September 2006, the IEMS did not show any abnormal readings. After the news of the USS Houston's leak in Japan broke, a review of the IEMS data for the period of the USS Houston's visit also confirmed that there were no abnormal readings recorded. Our IEMS has therefore provided independent verification that public safety was not compromised at any point during the USS Houston's port call in Singapore in September 2006. Our Defence Science Organisation scientists have also assessed that based on the figures provided by the United States Navy, the potential exposure is 100,000 times less than exposure from natural radiation in a year.

With the assurances from the US, verification from the data collected from our monitoring system and our own experts' assessments, I am confident that there was no adverse impact on public health, marine life or the environment as a result of the USS Houston's port call in Singapore in September 2006, and that the safety of Singaporeans was not compromised by the reported leak.