Radiological consequence analysis for hypothetical accidental release from Nigerian Research Reactor-1.

Radiological dispersion study is a key element in safety analysis report (SAR) of every nuclear facility for the purpose of emergency response planning. In this work, computational approach was used to determine the total effective dose and ground deposition at critical positions onsite and offsite of the Nigerian Research Reactor-1 (NIRR-1) facility which will be useful in the ongoing development of final SAR for NIRR-1 Low Enriched Uranium (LEU) core. In the methodology used, NIRR-1 LEU core was depleted with TRITON module of SCALE 6.2.3 code and the fission inventory in the core was calculated after a continuous operation at full power of 231.931MWD/MTU for 918 Effective Full Power Days (EFPD) at an operation regime of 3 h per day, 3 days per week and 48 weeks per year. Hot Spot was employed for atmospheric transport and dose calculations with consideration of different accidental scenarios in which 20%, 30%, 60% and 100% gaseous inventory was hypothetically released into the atmosphere. From the results obtained, the total effective dose to maximum exposed workers at 10 m and maximum exposed members of public at 300 m from the reactor were 3.10mSvand0.43mSv respectively for the worst-case scenario with 100% release while the maximum ground deposition was 5.5×106Bq/m2 with corresponding maximum ground shine dose rate of 7.5×10-4mSv/hr. This results are at least one order of magnitude below the dose limits recommended by the International Commission on Radiological Protection (ICRP) and indicate that the present LEU core of NIRR-1 is unlikely to cause any detectable health effect on workers and members of public in the event that 100% of its gaseous inventory is released into air in the environment. Hence it could unequivocally be said that the population is safe from the operation of NIRR-1 in its present location.

Preoperative staging of rectal cancer: pelvic MRI plus abdomen and pelvic CT. Does extrahepatic abdomen imaging matter? A case for routine thoracic CT.

OBJECTIVE: To assess the quality of preoperative magnetic resonance imaging (MRI) staging of rectal cancer, and the clinical significance of abdomen and pelvic computed tomogram (CT) scans in preoperative staging of rectal cancer in a district general hospital. We postulated that the 'metastatic yield' of extrahepatic abdominal imaging is poor, and rarely altered management of rectal cancer. METHODS: This is a retrospective study of preoperative MRI, CT scans and postoperative histology results of patients who had definitive surgery for rectal cancer at the Mid-Staffordshire General Hospitals NHS Trust over a 36-month period. Preoperative multiplanar pelvic MRI locoregional staging was compared with eventual histology. The incidence of and significance of abdomen and pelvic CT detected pathology (including metastasis) in the management of rectal cancers was also assessed. RESULTS: Preoperative pelvic MRI correctly predicted 'clear' Circumferential resection margins, in 28 of 29 patients who had primary surgery. This is comparable with many published studies. Significant CT detected pathology (including metastasis) on preoperative abdomen and pelvic CT scans was uncommon, and did not influence management of any rectal cancer patient in our study. DISCUSSION: Given that exclusive CT detected significant pathology caudal to the liver (extrahepatic abdomen) is rare, can full abdomen and pelvic CT scans be justified for preoperative staging of rectal cancers? - especially where chest X rays are employed for lung staging. Preoperative thoracic and upper abdomen CT scan may be a more productive use of resources. Full abdominal scans may be more appropriate for selection of rectal cancer patients with isolated liver metastasis for metastasectomy.

Standardization of NIRR-1 irradiation and counting facilities for instrumental neutron activation analysis.

The first nuclear reactor in Nigeria, the Nigeria Research Reactor-1 (NIRR-1), is a Miniature Neutron Source Reactor (MNSR). It was specifically acquired for elemental analysis by the neutron activation analysis (NAA) technique. In this work, routine experimental schemes for the determination of over 30 elements of interest in different sample matrices have been developed. In order to validate the experimental procedures the following standard reference materials, IAEA-359 (Cabbage), IAEA-336 (Lichen), GSR-5 and GSD-11 (Chinese Geochemical Rock Standards), as well as IAEA-SL-3 and IAEA-405 (Sediments) were analyzed. Validated results are presented for the following elements Al, As, Au, Ba, Br, Ca, Ce, Cl, Co, Cr, Cs, Cu, Dy, Eu, Fe, Ga, Hf, In, K, La, Lu, Mg, Mn, Na, Rb, Sb, Sc, Sm, Ta, Tb, Th, Ti, U, V, Yb and Zn. To further assess analytical capabilities of the facilities, the detection limits are presented.

Antioxidants enhance the susceptibility of colon carcinoma cells to 5-fluorouracil by augmenting the induction of the bax protein.

5 Fluorouracil (5 FU), the most effective systemic chemotherapeutic agent in the management of advanced colorectal carcinoma acts by inducing apoptosis. Response rates, approximately 20% is improved by folinic acid. This study investigates similar modulation of 5 FU-induced apoptosis by oxidant quenching. A five-fold reduction of intracellular oxidant levels by antioxidants N-acetylcysteine and vitamin E did not induce apoptosis, it however augmented pro-apoptotic bax protein expression, and apoptotic response to a non-toxic dose of 5 FU in the colorectal cancer cell lines colo 201 and colo 205. This suggests that reduction of intracellular levels of reactive oxygen species enhance susceptibility to 5 FU (apoptotic stimuli) by augmentation of bax expression.