Tackling nuke waste in Singapore backyard

Stringent measures in place here to ensure safety
Melissa Pang & Poon Chian Hui Straits Times 21 Apr 11;

TUCKED away in a secret location in Singapore is a storage facility where radioactive waste is kept, waiting to be disposed of safely.

It is operated by the little-known Centre for Radiation Protection and Nuclear Science, which regulates the import, export, sale, use, handling and disposal of radioactive material in Singapore.

That radioactive material exists here may come as a surprise to some, said Professor Tso Chih Ping, a visiting professor at Nanyang Technological University (NTU) who is trained in nuclear engineering.

However, such material has been used in Singapore and in most countries for a long time.

Nuclear experts interviewed by The Straits Times said hospitals were the biggest contributors of radioactive waste, due to their use of 'nuclear medicine' - for example, scans and radioactive treatments for conditions such as thyroid cancer.

The rest comes from industrial use and research facilities.

The Ministry of Health said there are 17 nuclear medicine specialists here, up from 15 in 2006. A total of 11 health-care institutions here - including five public hospitals and three national specialist centres - offer nuclear medicine services.

A National Environment Agency (NEA) spokesman said the increased use of nuclear medicine is one reason the amount of radioactive waste in Singapore has been rising.

About 1,450kg was generated last year. This is about 20 per cent higher than in 2008, when 1,210kg of radioactive waste was thrown away.

Radioactive waste, like toxic industrial waste, must be properly disposed of to minimise harm to the environment and human health, said Prof Tso.

Dr Daniel Quah of the National Cancer Centre Singapore pointed out how radioisotopes, used in cancer treatment, can be abused.

For example, people can use them to make radiation dispersal devices - known as 'dirty bombs'.

'These are designed to scatter radioactive debris over a wide area... and can possibly cause casualties through radiation sickness,' said the registrar from the centre's department of radiation oncology.

NTU's Assistant Professor Zhao Jiyun, who has done research in nuclear waste treatments, said radioactive materials generated from medical equipment typically do not pose much danger as they have short 'lives' - meaning the radioactivity will die off after some time.

'The waste is usually stored to wait for the radioactive materials to decay. Then, they are safely disposed of,' said Prof Zhao.

NEA's spokesman said that, in general, Singapore does not generate waste that is highly radioactive.

There are two types of radioactive waste. The first are items such as types of machinery, which emit radiation at levels above the limits set by the Radiation Protection Act.

Such radioactive sources have to be returned to the country of origin. Before shipping them back, they are securely kept at the nuclear centre's storage facility. They are packed according to the type and amount of radioactive material.

For example, those that emit low levels of radioactivity can be placed in ordinary metal drums.

The second type are objects that have been used to handle radioactive material. These could include needles, gloves and syringes used in hospitals, research institutes and universities.

As this kind of waste is not as radioactive, it is allowed to be disposed of in Singapore once its radioactivity has decayed to below-exemption levels. But before this is done, the waste producer has to complete a disposal form and obtain the nuclear centre's endorsement.

One of its inspectors will then conduct checks on samples of the waste to verify that the levels of radioactivity are indeed safe.

Last week, a newspaper in Hong Kong reported that at least 2,000 radioactive materials used in civilian sectors such as industry and medicine went missing in China as a result of poor management. In addition, more than 1,000 people were exposed to high amounts of radiation in China in about 300 accidents between 1988 and 1998.

Fortunately, stringent measures have kept radiation-related incidents to a minimum here, with just one such incident reported since the centre was set up in July 2007.

In December the same year, some workers failed to follow the work safety procedures when operating industrial X-ray equipment during an inspection of aircraft components. It led to one worker sustaining radiation burns on his fingers.

The company was subsequently prosecuted by the centre for failing to register two of the employees as radiation workers, and the supervisor was charged with failing to report the accident to the centre within 24 hours.

While acknowledging common fears about radiation, Prof Tso advised against being alarmist.

Last month, the Agri-Food and Veterinary Authority detected radiation on samples of vegetables from Japan. Its chief executive said then that an adult would need to eat 3.5kg of these vegetables to receive a level of radiation exposure similar to one X-ray, and 184kg to reach a level equivalent to the normal background radiation that a person is exposed to in a year.

Prof Tso said: 'The low radiation level must be viewed in the perspective of the natural radiation level that everybody in the world has been receiving, since the dawn of man.

'Somehow we don't have the same fear about fire accidents... That radiation is invisible and not understood by many could be part of the reason.'

How radiation heals
Straits Times 21 Apr 11;

RADIATION can kill - but in small doses it can also heal.

From detecting heart blockages and treating thyroid disorders to killing cancer tumours, nuclear medicine is increasingly being used all over the world.

Today, more than 10,000 hospitals worldwide use radioactive isotopes in medicine, with 90 per cent of procedures involving diagnosing medical ailments. In 2008, up to eight million nuclear medicine procedures were performed in Asia, out of 30 million done globally.

This number is growing at about 10 per cent every year, according to the World Nuclear Association. In cancer treatment alone, more than 15 types of radioactive isotopes can be used to weaken or destroy cancer cells, in the form of radiotherapy.

For instance, radioactive iodine is used to treat early-stage prostate cancer in men, said Dr Daniel Quah of the radiation oncology department at National Cancer Centre Singapore. Here, pellets containing the iodine are inserted into the patient's prostate gland. He will be discharged from hospital, carrying the pellet in his body. Low doses emitted from the pellets help to kill nearby cancer cells. The iodine will 'decay' in a few days.

A branch of nuclear medicine, nuclear cardiology, also uses radioactive elements to diagnose ailments. Commonly used is the myocardial perfusion imaging test, which assesses blood flow to the heart.

Here, a patient is first injected with a radioactive isotope. Then, gamma cameras - which capture radioactivity - are used to scan his heart during rest and exercise.

'The isotope is used to capture blood flow as the heart muscle would take it up,' said Dr Fahim Jafary, a nuclear cardiologist at Tan Tock Seng Hospital (TTSH). A healthy person would show the same degree of blood flow during both activities. 'There is no other technology that allows us to capture images of blood movement,' added Dr Jafary.

Other uses are bone scans to check for fractures, positron emission tomography (PET) scans to track cancer stages and radioactive treatments for thyroid problems and cancer, said Dr Anthony Goh, who is in charge of nuclear medicine and PET at Singapore General Hospital. The hospital runs the largest centre for nuclear medicine in the region.

The radioactive substances may be taken orally or by inhalation, while others may be injected into a vein or directly into a cancer tumour, said Dr Goh.

Although this branch of medicine has been well-established - it first came about in the 1950s - new developments are up and coming. New radioisotopes are in the pipeline - such as those which will turn radioactive only while inside the body, said Dr Quah, adding that researchers from Japan, Russia and Argentina are working on a device that will control the onset of radioactivity 'with a flip of a switch'.

This will do away with the need to set aside storage space at the hospital to keep these radioactive substances, he added.

POON CHIAN HUI, MELISSA PANG