Mr. Maung Maung Tin
Scientist
Atomic Energy Department
Myanma Scientific And Technological
Research Department
Myanmar

The current status of radioactive waste management in Myanmar including the recent formation of national level authority, policy, rules and regulations, safety standards, regional repositories and their designs, remedial measures as well as future strategy are described. To keep the discharge of radioactive waste to environment as low as reasonably achievable (ALARA), a proposal for the disposal of radioactive waste generated from replacement of radium Brachytherapy for cancer treatment by safer afterloading devices are also described in detail. The current status of IAEA model project "INT/9/145 Upgrading Radiation Protection and Waste Management Infrastructure in Myanmar" is presented.

Although Myanmar is a non-nuclear country, uses of ionizing radiation, radioisotopes and radioactive sources to some extent for health, social and economic benefits have been started since late 1950's in Myanmar. The main sources of radioactive wastes are mainly from hospitals that use short-lived radioisotopes for nuclear medicine purposes. Spent seal sources are generated from the application of radioactive sources in medical diagnosis, treatment and agricultural research.

When considering the use of radio nuclides for a given purpose, there must be detailed planning, not only for the use itself and the associated safety precautions, but also for the safe handling of the resulting radioactive waste. When using short-lived radio nuclides, waste management may involve simply collection and storage of the waste for decay until they can be exempted from further regulatory control. If radionuclides with long half-lives are used, waste management may have to include not only collection and storage, but also more complicated activities such as conditioning and disposal.

It is important carefully evaluated in the context of the national waste management program, before radionuclides are produced, imported or purchased. Information on waste management shall be submitted already when applying for a license to produce, import, purchase or use radionuclides.

With the uses of ionizing radiation and radioactive sources in the country are expanded it becomes imperative to establish an overall radiation protection infrastructure. Hence, the Myanma Atomic Energy Committee ( MAEC) formed on 7 August, 1997 (Fig. 1) has prepared fourth draft of Myanmar Atomic Energy Law and has been submitted to the cabinet. The MAEC had prepared radiation protection regulations for the establishment of a legal basis for a radiation protection regime in the country. In 1993, the IAEA provided assistance under the project MYA / 9 / 003 with the objectives: to establish a radiation protection infrastructure in the country and introduce internationally agreed basic safety standards.

The Atomic Energy Department, Myanma Scientific and Technological Research Department is responsible for carrying out research and development in radioactive waste management.

The basic policy of radioactive waste management in Myanmar are as follows:

• Radioactive waste generation from atomic energy activities should be minimized.
• Any discharge of radioactive liquid and gaseous waste to the environment should be kept as low as reasonably achievable ( ALARA ).
• Handling, treatment and disposal of radioactive waste should be carried out by taking the environmental consideration into account.
• Solid wastes and solidified wastes should emplaced at nuclear site specially constructed for that purpose.
• Waste management problems are to be taken into account before any large energy program is undertaken.
• Research and development in waste management should be carried out to support the safety aspects of future energy program.

Management of radioactive waste shall be in accordance with waste management policy established by the Myanma Atomic Energy Committee and such policy shall be aimed to protect human health environmental without imposing and undue burden on the future generations.

The propose waste management policy has three components, namely:

• The waste is returned to the manufacturers.
• The waste is stored by licensees.
• The waste is sent to National Waste Center.

Under this policy the waste shall not be disposed into the environment save those with a very short half-life. The policy also requires the Myanma Atomic Energy Committee to establish a National Waste Center.

Co-60 teletherapy machines have been used for radiotherapy in three big cities hospital. Radiophermacy techniques for preparation of generator-produced radiophermaceuticals, radiobiochemistry in medical application of radioisotopes, radioimmunoassay procedures for thyroid related hormones, cortisone and sex hormones using bulk regents have been performed in department of nuclear medicine Yangon General Hospital. Department of Medical Research has undertaken application of nuclear techniques in the identification of pharmacological active groups/ compounds present in the medical plant extracts, immunoradiometric assays (IRMA) using monoclonal antibodies for the detection of circulatory or urinary antigents in patients with filariasis or malaria and IRMA methods for assessment of malaria transmission.

Recently, a number of private hospitals have entered the field of nuclear medicine. In addition to these, there are hospitals and clinics used diagnostic X-ray machines which are not more than 400.

Brachytherapy plays an important role in the treatment of carcinoma of cervix at all stages of the disease. Intracavitary application of sealed sources has been the mainstay of treatment for control of primary tumours as this could deliver very high local dose with extremely low dose to the surrounding structures. The natural advantage of accessibility of tumour and good tolerance are the main factors for delivering high dose to the cervix uterine cavity and vaginal fornices for effective control of the primary disease. Cancer of cervix being one of the most common sides of cancer in Myanmar, no oncology centre can effectively function without facilities for intracavitary treatment.

Afterloading techniques are preferred to the conventional preloaded techniques in brachytherapy because of considerably reduced radiation exposure to workers and public. In afterloading technique, the source positions are initially fixed, as required, by the insertion of appropriate applicators without the sources and verified radiologically. This procedure also enables accurate dose delivery.

While brachytherapy is very useful, it must be stressed that careless handling of sources and unscrupulous practices can result in higher doses to medical and paramedical staff as also members of the public.

Brachytherapy practices were initially established with the used of radium sources. However, realization of the inherent hazards associated with the use of radium prompted the replacement of it with suitable substitutes Cs-137 with a half-life of 30 years and gamma energy of 0.66MeV is the most preferred radionuclide for application in intracavitory therapy. So Myanma Atomic Energy Committee has made concerted efforts to withdraw radium from hospital and replace with Cs-137 due to their hazards with its use. Efforts are in progress for the withdrawal of all most of all Ra-226 sources and their safe disposal at national waste management facility after proper conditioning process.

We have an experience in the conditioning of spent radium needles embedded in concrete in a 200 litre drum.

The conditioning of spent radium needles into a 200 litre steel drum with concrete represent a Type A package (1).The limit on activity in the package depends on the Ra-226 radionuclides where the optimization of the conditioning can be determined. In this case 0.02Tbq or 0.5 Ci of Ra-226 represent the highest activity in a Type A package (1).

In the conditioning process, the following procedure steps were used (Fig. 2)

1. New 200 litre steel drum used was inspected to assure free of corrosion, mechanical damage and defects.
2. The mixing of concrete was done by using an electric concrete mixer where the ratio used were : cement : sand : gravel : water to 1:2:4:0.4 parts, respectively. After mixing, the homogenous concrete mixture was poured into the drum and frequent tapping on the outside of the drum and shaking on the mixture by a vibrator was used to assure that no voids or air pockets have been formed in the wet concrete. The first filling of the concrete was to the one-third level of the drum and then allowed to settle for about 30 minutes.
3. Six reinforcing iron rod ( 10 mm diameter, 840 mm long ) was inserted into the concrete in the drum while the concrete begin to harden.
4. PVC pipe (16 inches diameter) was used as a mould to form a hole in the concrete. At the upper end, two small holes were drilled where and iron rod(60cm long ) was inserted at both holes to form a holder to pull the mould while the concrete was hardening.
5. The PVC pipe was placed upright at the centre of the drum and a concrete block was placed on the upper end of the PVC in order to hold PVC pipe still. This was to avoid any movement or floating when further filling of concrete into the drum was made.
6. The second filling of concrete was up to the 4/5 level of the drum and was allowed to settle and set. After one hour, the PVC pipe was pulled out resulting the formation of an empty hole 40cm diameter in the middle of the drum.
7. The concrete in the drum was allowed to dry for five days in a secure place and then ready for use to condition the spent radium needles.

Spent radium needles were put into additional lead pot for additional shielding and then placed in the center of a clean and unrusted 200 liter steel drum with concrete. Temporary shielding of lead bricks and concrete blocks were used to reduce external dose exposure to the operators while transferring the radium needles from the plastic test-tube into the lead pot and during conditioning process. The appropriate radiation protection and handling procedures were used during the transfer.

In the first conditioning process, fifty units of Ra-226 needles with a total of 80 mCi(80 mg) were transferred into a lead pot. The lead pot was then closed and then sealed around with plastic tape. Due to the long half-life of Ra-226 and release of radon gas, the filled and sealed lead pot was put into a tin container and then sufficient activated charcoal was added completely fill the tin can. The tin can was closed airtight and sealed around the lid with plastic tape. By using a manual hydraulic truck lift, the tin can was transferred and lowered into the hole at the center of the concrete in the drum. The distance between the trucklift handler and the tin can was one metre with radiation dose rate between 0.2-0.025 mSv/hr (2-2.5mR/hr).

The final process in the conditioning was the filling of more concrete to fill the hole empty space including centre hole which contain the spent radium needles. The concrete was then left to settle and harden for five days. A permanent label made of aluminum sheet and pressed into U-shaped containing all the relevant data connected to the conditioned spent radium needles was attached permanently to the surface of concrete. The drum lid was installed and bolted where the bolt ring was tightened by screwing the closure device.

Quality assurance defining the characteristic for each disposal package was done where an extensive set data was produced for each waste package. The documentation, radiological control labeling including marking of packages was described on the label.

The time taken in transferring of radium needles from the plastic test-tube to the lead pot prior to be conditioned is between 10-15 seconds. During the transfer, the external radiation reading at the side without shielding was 1.2 mSv/hr while at the side shielding (working area) at a range 0.1-0.3 mSv/hr. The time taken for the whole transferring process for the 50 units of radium needles was 10 minutes. The surface radiation dose of the filled lead pot was 1.8 mSv/hr. It was estimated that radiation exposure received while transferring was 0.05 mSv, 25% less than permitted per day for a radiation worker 0.2 mSv/day.

Radiation safety procedures were continuously being done during conditioning operation to ensure the operator does not receive unacceptable exposure. Smear test was done on the outside of the drum and monitoring on suspected contamination by contamination radiation meter in the working area shows that there was no contamination present. The surface radiation dose of the drum at a distance of one metre with the values of 0.3 mSv/hr and 0.01 mSv/hr respectively, is still below the restricted values of 2 mSv/hr and 0.1 mSv/hr respectively, recommended by IAEA.

During the conditioning process, all procedures were followed strictly and the spent radium needles were properly immoblished in the 200 litre drum with concrete and properly stored at the national waste management centre.(Fig. 3)

Proper documentation were prepared for the storing and inventory purposes and easily be retrieved. The cost for the operation is very cheap and the material for conditioning is easily available in the country. It takes about 10 days to complete the whole operation.

At present we do not have nuclear power plant, research reactors or fuel cycle facilities and as such we do not have problems related to high level waste but appropriate measures are to be taken for disposal of these sources if any.

However, the current situation of our country demands safe and systematic handling and storage of radioactive waste until their disposal. The small amount of activity and expected volume of radwaste is handled conveniently at MAEC waste disposal facility but site for ultimate waste disposal facility (repository ) is yet to be finalized.

All the departments using ionizing radiation sources have followed the IAEA Safety Rules and Standard ( 1982 )with care and caution, no radiation hazard or accident or incident has ever occurred at all.

1. INTERNATIONAL ATOMIC ENERGY AGENCY, Conditioning of Low and Intermediate Level Radioactive Waste, Tech . Rep . Ser . 222, IAEA, Vienna ( 1983).

2. INTERNATIONAL ATOMIC ENERGY AGENCY, Nature and Magnitude of the Problem of Spent Radiation Sources, IAEA-TECDOC-620.

3. INTERNATIONAL ATOMIC ENERGY AGENCY, Handling, Conditioning and Disposal of Spent Sealed Sources, IAEA-TECDOC-548, Vienna ( 1990).

4. INTERNATIONAL ATOMIC ENERGY AGENCY, Guidance on the Requirements for Radioactive Waste Management Legislation for Application to Users of Radioactive Materials in Medicine, Research and Industry, IAEA-TECDOC-644.

5. INTERNATIONAL ATOMIC ENERGY AGENCY, Management of Radioactive Wastes Produced by Users of Radioactive Materials, Safety Series 70, IAEA, Vienna ( 1985).

6. MYANMA ATOMIC ENERGY COMMITTEE, Atomic Energy Law ( Fourth Draft ) (1995).

7. INTERNATIONAL ATOMIC ENERGY AGENCY, REPORT OF RAPAT MISSION TO MYANMAR (1993).

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