Car-borne survey and dose assessment from external radiation exposure in Bangka Island

With a history of more than 200 years of tin mining, Bangka Island has brought along a byproduct of heavy minerals containing radionuclide elements. There are some concerns about this byproduct material contributing to natural radiation in the environment. In this study, a car-borne survey was conducted to accurately assess natural background radiation in Bangka Island. Indoor and outdoor ambient dose rates in 146 houses were also measured to assess the radiation dose from external exposure received by the public. Soil samples were collected and measured using a gamma spectroscopy system to evaluate the contributions of specific radionuclides to external terrestrial exposure. From 3790 measurement points during the car-borne survey, the highest ambient dose equivalent rate was 596 nSv h-1 measured in Muntok area, with a mean value of 101 nSv h-1 and a median value of 95 nSv h-1. The ambient dose equivalent rate distribution map showed a relatively higher value in the northern coastal area of the island, where the Pemali tin deposit is located. The annual effective dose received from external radiation in the 146 houses in Bangka Island ranged from 0.44 to 1.30 mSv year-1, with a median value of 0.66 mSv year-1. The soil contained a relatively high amount of thorium (232Th), which contributed 69% to external radiation exposure in Bangka Island.

Abnormal control rod withdrawal analysis for innovative research reactor using PARET-ANL codes

Innovative Research Reactor 50 MW (RRI-50) is a conceptual design of an Indonesia's high-power innovative research reactor, which is designed to produce a maximum neutron flux as high as 1.0 × 1015 n/cm2 s and thermal neutron flux of 5.0 × 1014 n/cm2 s. In this study, the design basis accident slow reactivity insertion is carried out. Reactivity insertion accident (RIA) caused by the inadvertent withdrawal of all fuel rod at normal rate is simulated by using PARET-ANL transient code. In the simulation accident is assumed to occur when the reactor is in operation at high power and at low power level. During transient, the fuel rods are assumed to be in the most effective positions with insertion rate of 0.049 $/s. This reactivity worth will give effect only if the fuel rod interlock system is failed to function properly and the operator action does not follow the standard operation procedure. The analysis results show that the reactor experiences scram when it reaches its protected power at high power level of 110 % (55 MW) at period of 5 s and at low power level of 3 MW at period of 120 s, and there is sufficient safety margin for the anticipated RIA caused by reactivity feedback.

Source term estimates of radioxenon released from the BaTek medical isotope production facility using external measured air concentrations

BATAN Teknologi (BaTek) operates an isotope production facility in Serpong, Indonesia that supplies (99m)Tc for use in medical procedures. Atmospheric releases of (133)Xe in the production process at BaTek are known to influence the measurements taken at the closest stations of the radionuclide network of the International Monitoring System (IMS). The purpose of the IMS is to detect evidence of nuclear explosions, including atmospheric releases of radionuclides. The major xenon isotopes released from BaTek are also produced in a nuclear explosion, but the isotopic ratios are different. Knowledge of the magnitude of releases from the isotope production facility helps inform analysts trying to decide if a specific measurement result could have originated from a nuclear explosion. A stack monitor deployed at BaTek in 2013 measured releases to the atmosphere for several isotopes. The facility operates on a weekly cycle, and the stack data for June 15-21, 2013 show a release of 1.84 × 10(13) Bq of (133)Xe. Concentrations of (133)Xe in the air are available at the same time from a xenon sampler located 14 km from BaTek. An optimization process using atmospheric transport modeling and the sampler air concentrations produced a release estimate of 1.88 × 10(13) Bq. The same optimization process yielded a release estimate of 1.70 × 10(13) Bq for a different week in 2012. The stack release value and the two optimized estimates are all within 10% of each other. Unpublished production data and the release estimate from June 2013 yield a rough annual release estimate of 8 × 10(14) Bq of (133)Xe in 2014. These multiple lines of evidence cross-validate the stack release estimates and the release estimates based on atmospheric samplers.

Genetic, antigenic and serologic characterization of human immunodeficiency virus type 1 from Indonesia

To examine the genetic and antigenic characteristics of HIV-1 in Indonesia, samples from 19 HIV-positive volunteers were studied. By a combination of PCR typing and DNA sequence analysis, 12 of the 19 volunteers were determined to be infected with HIV-1 clade B and seven with clade E. Six of the seven Indonesian clade E isolates were from volunteers associated with the Indonesian Military during a peacekeeping mission in Cambodia. Infectivity reduction neutralization assays showed that the Indonesian E viruses were effectively neutralized by Thailand clade E HIV-1 antisera but not by U.S. clade B antisera. The Indonesian clade B virus tested was neutralized by U.S. clade B antisera and not by the Thailand E antisera. Using a previously described serologic typing ELISA based on clade B and E V3 peptides, genetic clade was accurately determined in eight of eight sera tested. This is the first report of the genetic and antigenic analysis of HIV-1 isolates from Indonesia. The data indicate that at least two genetic and antigenic HIV-1 clades (clade E and B) circulate in Indonesia.

Two years' investigation of epidemic hepatitis E virus transmission in West Kalimantan (Borneo), Indonesia

Two years' follow-up investigation of a hepatitis E virus (HEV) outbreak in West Kalimantan, Indonesia in 1991 was carried out to investigate the epidemiology of epidemic HEV transmission and the persistence of the immunoglobulin G (IgG) antibody response. Sixty cases identified as anti-HEV IgG positive during the outbreak in 1991 were matched with 67 controls and examined, together with 318 members of their families. Overall, the prevalence of anti-HEV IgG among the 445 subjects (representing 127 households) was 59%. There was no significant difference in anti-HEV prevalence between cases (72%) and controls (61%). Loss of detectable anti-HEV IgG after 2 years was demonstrated in 17 of 60 subjects (28%) who were originally positive for anti-HEV in 1991. The mean number of anti-HEV positive subjects per household was 2.04. Cross-sectional prevalence of anti-HEV IgG increased significantly with age (P = 0.01). When communities were grouped into areas of low (< 40%), medium (40-59%) and high (> or = 60%) anti-HEV prevalence, use of river water for drinking and cooking (P < 0.001), personal washing (P < 0.0001), and human excreta disposal (P < 0.001) were associated with high prevalence communities. Conversely, boiling drinking water was negatively associated with increased prevalence (P = 0.02). Subnormal rainfall during the month (August) leading up to the 1991 outbreak (19 cm compared to the monthly mean of 209 cm in 1985-1993) may have contributed to favourable epidemic conditions.