IAEA Soil-6 is a reference material with a certified value for 226Ra fall between 69.6 – 93.4 Bq/kg at 95% confidence level. This material has been used as a sample and performed repeat measurement weekly between years 2006 – 2009 using a same gamma spectrometry system. The activity concentration of this material is calculated automatically using the operational commercial software and compared with activity obtained from the manual calculation. Study found that only 76.9%, 64.1%, 56.3%, and 79.3% of the results from the software calculation lie within the confidence level for year 2006, 2007, 2008 and 2009, respectively. However, u-score calculation revealed that 94.9 %, 89.7%, 79.2% and 84.9% data set have no significant bias (u < 2.58) for year 2006, 2007, 2008 and 2009, respectively. On the other hand, all manual calculation data were found to be within the 95 % confidence level. Factors suspected to cause differences between these two approaches were discussed here. Manually peak search, marking and calculation still remains as the preferred option for calculating the gamma radionuclides activity unless limitations of the spectrum analysis software, as described in this paper can be resolved/improved upon.
Results ofthe bioaccumulation study anddose assessmentof Th-232 in whole-body Anabas testudineus are presented. The objective of this study was to evaluate the effect of Th-232 concentration activity on the laboratory bioaccumulation and total dose rate in Anabas testudineus. Anabas testudineus adults were exposed to different waterborne Th-232 levels: 0 Bq/L (control), 50 Bq/L and 100 Bq/L for 30 day (uptake phase). Whole-body uptakesof Th-232 in Anabas testudineuswere calculated and total dose ratesusing ERICA Assessment Tool were also estimated. The results showed the increase of waterborne Th-232 concentration corresponded to a progressive increase of Th-232accumulation and total dose rate (internal and external) in whole-body Anabas testudineus.Considering the ERICA dose rate screening value of 10 μGy/h, the findings can be concluded the estimated of total dose rate (0.38 –1.29μGy/h) in Anabas testudineuswasin orderof small magnitude. Nevertheless, these results showed that the Anabas testudineushas a potential to accumulate thorium.
On March 11, 2011, a serious accident occurred in Daiichi nuclear reactor plant, Fukushima,
Japan which caused radioactive materials been released into the atmosphere in the form of
aerosols and dust particles. Sea water around the plant was also found contaminated with high
radioactivity readings. These radioactive materials could be transported by the winds and ocean
current across international borders and cannot be controlled by human. Thus, a continuous
monitoring activity of radionuclide content in the air and sea water needs to be conducted by the
authorities. In addition to radioactivity monitoring, Malaysia should also control the entry of
contaminated food in order to prevent radionuclide ingestion by human. The radionuclide 131I,
134Cs and 137Cs were used as a measure of pollution levels and counted with gamma spectrometry
using standard analysis method suggested by AOAC International. In this paper, details description
of the role of Radiochemical and Environment Group, Nuclear Malaysia who’s responsible in
analyzing the radioactivity in the food samples due to Fukushima Daiichi, Japan accident was
included. The radioactivity limit adopted and analysis results from this monitoring were discussed
Nur Humaira’ Lau Abdullah, Zal U’yun Wan Mahmood, Norfaizal Mohamed @ Muhamad, Nazaratul Ashifa Abdullah Salim, Ahmad Nazrul Abd Wahid, Nor Dalila Desa, et al.
A glasshouse experiment was performed to evaluate the uptake of grasses viz. Napier and Vetiver
in radiophytoremediation of caesium-contaminated soil. The radiophytoremediation experiment
was designed according to the Randomized Complete Block Design (RCBD). The grasses were
grown in troughs filled with soil mixed with a known specific activity of 134Cs. Initial Cs activity and
activity after different cultivation time intervals of 1, 3, 6 and 9 months were analyzed using gamma
spectrometer direct measurement. The results showed the uptake of caesium by Napier and Vetiver
after 9 months with the transfer factors (TF) were 4.70 and 6.25, respectively. The remediation of
caesium from the contaminated soil during the study period was 98.08% for Napier and 98.21% for
Vetiver. Both grasses have been found to accumulate caesium, with Vetiver accumulating higher
than Napier. Thus, the present study suggests that Vetiver could be used as a potential plant for
radiophytoremediation of caesium.