[en] Sputtering of both polycrystalline and single crystal gold samples under ion bombardment has been studied using a time-of-flight spectrometer to detect the sputtered atoms and to measure their energies. D⁺, He⁺, Ar⁺, Kr⁺ and Xe⁺ beams at 10 and 20keV were used. A new radiofrequency ion source was built and the 30keV accelerator and its pulsing system was redesigned for these experiments. For heavy ion bombardment, the energy spectra is like E^-2 for energies in excess of 10eV, but for light ions ejections at higher energies are of relatively greater importance. The time-of-flight spectra from D⁺ and He⁺ bombarded gold targets show two broad peaks, one at energy higher than that calculated for the direct recoils from the ingoing ions which suggests that the contributions from reflected ions are responsible while the other can be attributed to the low energy recoils mostly from collision cascades. (author.)

[en] Life without water is not possible. Like other natural resources, the global resources of fresh water are unevenly distributed. The world population is increasing at very rapid rate while the natural water resources remain constant. This gap is expected to widen dramatically in the near future. Our country like most countries in the east suffer from water stressed condition. Desalination is only the logical or available solution. In MED units, the feed seawater sprayed individually in each effect is heated to form pure vapors, which condense to form product water. Irrespective of the continuous development of the desalination industry the thermal desalination is still expensive. The study presented in this thesis is motivated by, to study the impact of various cost controlling parameters on the performance of MEE desalination process. KANUPP has two desalination plants (RO and NDDP). The NDDP has parallel feed cross flow multiple effect evaporation (MEE-PC) configurations. The study presented in this thesis describes a simplified steady state mathematical model to analyze the MED systems. The results obtained by the model are compared with the NDDP data. The developed model is used to investigate the effect of the parameters controlling the product water cost. These parameters includes thermal performance ratio, cooling water flow rate and heat transfer area. It can also be used to study the effect of variation in the operating conditions of the plant on the plant performance. The effect of the process variables on the performance of MED is carried out. This includes the effect of number of effects, intake seawater salinity and heating stream temperature, vacuum condition in term of vapor temperature of last effect. (author)

[en] Published in summary form only

[en] The objective of this thesis project was to study the thermal hydraulic parameters of research using standard computer codes. The code PARET was used for this purpose. Initially, the steady state analysis was made for IAEA Benchmark reactor. The results include temperature (liquid, clad, fuel centerline) distribution and enthalpy distribution at axial node points and pressure drop at these points both for the hottest channel and average channel. Maximum fuel, clad and liquid temperatures were computed to be 77 deg. C, 75 deg. C, 53 deg. C for hot channel and 62 deg. C, 61 deg. C, 47 deg. C for the average channel respectively. Later, the effect of coolant flow rate on power at onset of nucleate boiling (ONB) was studied. The power at ONB were computed to be 26.7, 24.3, 21.9, 19.4, 16.9 and 14.4 MW for flow rates of 1000, 900, 800, 700, 600 and 500 m/sup 3//hr respectively. A comparison of thermal hydraulic parameters was also made for different number of plates (23, 21, 19, 17 and 15) per fuel element. All analyses were made for IAEA Benchmark reactor LEU core. (author)

[en] Several techniques have been proposed to improve the boiling heat transfer process, including surfaces with re-entrant holes, porous sintered metal coatings, etc. The purpose of this work is to examine the surface effects in boiling heat transfer with particular emphasis on the role of micro-finned surface. The fins are produced on the test surface by a milling machine. The experiments for the most part uses a simple quenching technique in saturated water, using Brass cylinders. The depth and the width of the fins are 0.5 millimeters. Auxiliary test is conducted using a cylinder with a smooth surface. The results have been compared using the nucleate boiling curves obtained from the experimental data, for both the smooth and micro-finned surfaces. The comparison indicated that the use of microfins can improve the cool-down time and thus can enhance the heat transfer. (author)

[en] Technical support for nuclear security matters is an important element for sustainability of nuclear security regime. An effective nuclear security system requires the availability of different types of sensor for intrusion detection and radiation detection equipment. Continued operation and sustainability of the security systems and radiation detection equipment is very essential for the prevention of the radioactive material from being stolen or unauthorized removal. Sustainability of such equipment and systems also requires timely technical support. Realizing the importance; PNRA has established a Technical Support Unit (TSU) to provide assistance at national level to ensure equipment life cycle management, provide assistance during and after a nuclear security event, support in designing, commissioning and acceptance of physical protection gadgetry installation for facilities using high activity radioactive sources, and expert advice on nuclear security matters. The TSU is equipped with tools, equipment, and experienced manpower for technical support. PNRA also developed tool for assessment of security measures taken at high activity radioactive sources. The TSU provides technical support to national organizations and licensees using radioactive sources in the areas of repair, maintenance and acceptance testing of radiation detection equipment (RDEs), provides expert advice's and support to Customs for combating illicit trafficking of nuclear/radioactive material. RDEs have been provided to Customs at selected entry/exit points at the boarders. The periodic testing of these RDEs is also carried out at TSU. TSU is further providing repair and maintenance to overcome the issues of high cost involvement in the R&M after warranty i.e shipment clearance and export control constraints; therefore PNRA provide technical support in repair and maintenance lab which has now limited capabilities of repair and maintenance. TSU also provides technical assistance to other national stakeholders in testing, calibration maintenance and troubleshooting of radiation detection equipment. The lab is equipped with oscilloscope, variable power supply, soldering station, mechanical and electrical tool kit, automated testing train etc. The lab has the capability to detect the fault and repair minor fault. The paper will highlight PNRA efforts for establishing technical support unit and its contribution for supporting national efforts for nuclear security. (author)

[en] The use of by-products as additives in brick industry is gaining increased research attention due to their effective role in decreasing the total energy needs of industrial furnaces. In addition, these additives leave pores upon burning, causing a decrease in thermal conductivity and affect the mechanical properties of bricks as well. In the present study, various proportions of coal and wheat husk were used as additives in the initial ingredients of clay bricks. Microstructure, thermal conductivity, coefficient of thermal diffusivity, water absorption, shrinkage, compressive strength and bulk density of fired clay bricks with and without additives were investigated. Clay bricks containing 5–15wt.% additives were found to be within the permissible limits for most of the recommended standard specifications. (Author)

[en] It is the radiation safety policy of PAEC/PINSTECH that all radiation exposure should be kept as low as reasonably achievable (ALARA). A code of practice against radiation hazards at PINSTECH was written in 1972 which regulated the conduct of radiation work at PINSTECH. Since the radiation work at PINSTECH has greatly increased, it was considered necessary to revise the code so as to incorporate the new concepts in this field as well as to help meet the present requirements of radiation protection. The procedures set forth in this code are mandatory and in no case should any of them be deviated except under an emergency situation which may be handled according to procedures laid down in a separate manual ''Emergency Procedures at PARR-PINSTECH'' (PINSTECH/HP--19). All those supervising or performing any kind of radiation work are required to study and adhere to these procedures. Copy of this code should be kept in every radiation laboratory for ready reference. (author)

[en] Background: Implants for open reduction and internal fixation of distal femoral fracture includes angle blade plate, rush nails, enders nail and interlocking nails. But all these devices are technically demanding and less effective in providing inter-fragmentary compression in osteoporotic bones. These problems can be solved with dynamic condylar screw (DCS).The objective of the study was to determine the frequency of different outcomes of distal femoral fracture treated with dynamic condylar screw Methods: This case series study was carried out in the Department of Trauma and Orthopaedics, Ayub Teaching Hospital Abbottabad from 1st October 2014 to August 2015, after approval of the ethical committee of the institution. Data of all patients with distal femoral fractures aged 20-70 years, recruited through emergency, OPD or consultant clinic collected on a proforma. Standard treatment of trauma was given to the patients. Detailed history was taken including the past medical and surgical history. Detailed examination including air-way, breathing and circulation, general physical examination and abdomino-pelvic examination was done in each patient. Investigations including urinalysis, haemoglobin percent, full blood count, X-ray (both AP and lateral view) of the involved femur (including hip and knee) was done. Results: Mean age of the patients was 43.18±14.647 ranging from 20 to 70 years. Mean duration of hospital stay in days was 2.21±1.111 ranging from 1 to 6 days. Patients follow-up assessment after 4 months of surgery for union of femoral fracture treated with dynamic condylar screw was found in 96 (94.1 percent), wound infection was found in 7 (6.9 percent), knee stiffness was found in 21 (20.6 percent) and limb shortening was found in 7 (6.9 percent). Conclusion: Dynamic condylar screw is an easy, scientifically less difficult and satisfying method of treatment for fractures of femur. (author)

[en] We have observed antipp annihilation at rest into Ksub(S)Ksub(S) using a hydrogen gas target at normal temperature and pressure. This channel is forbidden from atomic antipp S states. A preliminary analysis gives a branching ratio of (2.2+-0.5+-0.5) x 10^-5. We have also observed the channel Ksub(S)X where X is a Ksub(S) or Ksub(L) escaping detection in our apparatus. The Ksub(S)Ksub(L) mode is allowed from atomic S but forbidden from atomic P orbitals. Using the known branching ratio of (7.8+-0.4) x 10^-4 for antipp→Ksub(S)Ksub(L) and our preliminary figure of (3.8+-0.4+-0.8) x 10^-4 for Ksub(S)X we deduce that the fraction of S state annihilation in hydrogen gas at NTP is (46+-10)%. This in turn yields an absolute branching ratio of (4.1+-0.9+-1.0) x 10^-5 for antipp→Ksub(S)Ksub(S) from P orbitals, showing that the (Ksub(S)Ksub(S)+Ksub(L)Ksub(L) mode is suppressed by an order of magnitude compared to the Ksub(S)Ksub(L) mode. 6 refs