L. G. I. Bennett

Modeling the dispersion of radionuclides released during reactor accidents aboard nuclear-powered vessels

A radioactive aerosol and vapor dispersion model, RADiM, has been developed to predict the distribution of acquired doses from radionuclides escaping into the atmosphere following a marine reactor accident. Designed as a decision aid for emergency response teams, RADiM is based on a Gaussian plume model, which considers decay and transmutation, as well as meteorological and terrain effects. An initially estimated source term can be adjusted for strength and composition, based on subsequent field survey measurements and gamma-spectroscopy. RADiM was validated using field release data and was compared to predictions from established codes. Possible accident scenarios were also examined.

A new microcomputer-controlled neutron activation and analysis system

A microcomputer-controlled irradiation and measurement system and a microprocessor-controlled sample changer have been installed at the SLOWPOKE-2 Facility at the Royal Military College of Canada (RMC). These systems can provide the gamut of instrumental neutron activation analysis (INAA) techniques for the analyst. Custom software has been created for system control, data acquisition, and off-line spectral analysis using programs that incorporate Gaussian peak-fitting methods of analysis. The design and use of the equipment is discussed, and the performance is illustrated with results obtained from the analysis of marine sediment and biological reference materials.

The determination of wear elements in lubricating oils by neutron activation analysis

Used lubricating oil analysis programs are currently employed by both the military and industry in an attempt to minimize some of the costs associated with equipment failure. The periodic determination of water elements in the lubricant of an oil-wetted system can provide very useful information on the condition or health of the system and an early indication of impending failure. In the present study, the application of Neutron Activation Analysis (NAA) to used oil analysis was investigated. The method developed allowed for the determination of fifteen elements (Ag, Al, Cl, Cr, Cu, Fe, In, Mg, Mn, Mo, Na, Ni, Sn, Ti and Zn) associated with engine wear or deterioration. Results obtained for the analysis of used naval diesel oils exhibited good agreement with results obtained by Atomic Absorption Spectrophotometry (AAS) methods. A drawback of the NAA procedure is that the determination of Fe, a major wear element in most systems, involves an analysis time of approximately one week.

The determination of eear elements in aircraft engine oil filter debris by neutron activation analysis

The increasing trend towards the use of fine oil filtration in modern jet engines suggests that the Spectrometric Oil Analysis Program (SOAP), which routinely monitors the health of aeroengines, may no longer be effective in detecting abnormal wear trends. Since the oil filter contains a wealth of information on wear in a system, it may be necessary to perform engine health monitoring through Filter Debris Analysis (FDA). In the present study, a method was developed for the determination of 19 wear elements (Ag, Al, Au, Cd, Co, Cr, Cu, In, Fe, Mg, Mn, Mo, Ni, Sb, Sn, Ti, V, W and Zn) in aircraft engine oil filter debris samples using the analytical technique of Neutron Activation Analysis (NAA). Results obtained by NAA for the analysis of two types of filter debris samples compared well with results obtained previously for similar samples and it appears that FDA should be very useful for following wear trends.

A transportable gamma spectroscopy system applied to the measurement of fission products

Normally, gamma-ray spectroscopy is performed by equipment positioned in the SLOWPOKE-2 Facility at the Royal Military College; however, there have occasionally been requirements for analyses externally. A transportable gamma spectroscopy system was thus assembled by acquiring a commercially available multichannel analyzer, analysis program and detector, and by designing and constructing a transportable shielding castle. It was then used to take measurements of fission product concentrations at several research reactors.

QUANTITATIVE FILTER DEBRIS ANALYSIS (QFDA) AS A MEANS OF MONITORING WEAR IN OIL-LUBRICATED SYSTEMS

In this study, the trace analytical technique of instrumental neutron activation analysis (INAA), using the SLOWPOKE-2 Facility at RMC, was used to develop an application termed Quantitative Filter Debris Analysis (QFDA). The preliminary step, which consisted of the quantitative analysis of filter debris samples from CH-124 Sea King helicopter main gear boxes (MGB) for 19 elements associated with engine wear, confirmed that distinct ranges of normal and abnormal wear rates exist in the CH-124 MGB and, more importantly, validated the INAA procedures. The second step, which consisted of the analysis of both oil and filter debris samples from the CF-188 Hornet aircraft engine by the INAA technique and an Atomic Emission (AE) method, confirmed that little useful wear information can be found in the oil of a finely-filtered engine system and demonstrated the potential of QFDA as a means of monitoring wear by analyzing the oil filter debris. What appears to be normal wear rate ranges were identified for the CF-188 Hornet aircraft engine. The potential of monitoring the wear health of oil-lubricated systems using QFDA was confirmed by this investigation.

The multi-role nature of the SLOWPOKE-2 facility at the Royal Military College of Canada

After up to a decade of successful operation of seven SLOWPOKE-2 reactors within Canada and in Jamaica, an eighth SLOWPOKE-2 research reactor was installed at the Royal Military College of Canada in 1985. Its open pool was one factor that allowed the authors to develop a variety of research capabilities beyond those being established for NAA. A description of the research projects to date will serve to indicate the diversity of this facility.

An automated data handling process integrating spreadsheets and word processors with analytical programs

A data handling process utilizing software programs that are commercially available for use on MS-DOS microcomputers was developed to reduce the time, energy and labour required to tabulate the final results of trace analyses. The elimination of hand computations reduced the possibility of transcription errors since, once the γ-ray spectrum analysis results are obtained and saved to a hard disk of a microcomputer, they can be manipulated very easily with little possibility of distortion. The 8 step process permitted the selection of each element of interests best concentration value based upon its associated peak area. Calculated concentration values were automatically compared against the samples determination limit. Unsatisfactory values were flagged for latter review and adjustment by the user. In the final step, a file was created which identified the samples with their appropriate particulars (i.e. source, sample, date, etc.), and the trace element concentration were displayed. This final file contained a fully formatted summary table that listed all of the samples results and particulars such that it could be printed or imported into a word processor for inclusion in a report. In the illustrated application of analyzing wear debris in oil-lubricated systems, over 13,000 individual numbers were processed to arrive at final concentration estimates of 19 trace elements in 80 samples. The system works very well for the elements that were analyzed in this investigation. The usefullness of commercially available spreadsheets and word processors for this task was demonstrated.

A set-up, calibration, acquisition and analysis program (SCAAP) for gamma-ray spectroscopy

A computer program entitled SCAAP (Set-up, Calibration, Acquisition and Analysis Program) has been designed to make gamma-ray spectroscopy easily useable by staff in laboratories at the Slowpoke-2 Facility at RMC and in support of the Canadian Forces Nuclear Emergency Response Teams (NERTs). The former group utilises gamma-ray spectroscopy for neutron activation analysis (NAA), while the latter may need to have inhalation dose rates calculated. The intent of this program, written using Microsoft Visual Basic, is to provide a simplified interface between the operator and the spectroscopy equipment and to provide the calculations necessary to produce results quickly. There are five sections (Setup, Calibrate, Acquire, Analyse and NAA) of which the first four are linked. In these sections, a checklist of procedures is presented and automated for the user to set up and calibrate the equipment and then to analyse spectra to provide various dose rates. In the unlinked section, NAA, gamma-ray spectra are analysed to provide elemental concentrations in samples.

INSTRUMENTAL NEUTRON ACTIVATION ANALYSIS IN SUPPORT OF IMPLEMENTATION OF QUANTITATIVE FILTER DEBRIS ANALYSIS

Aircraft engines and transmissions are regularly monitored by several integrated techniques such as periodic analysis of the metallic wear debris deposited in the lubricating oil, termed Aircraft Oil Analysis (AOA). Trending of these results indicate to the fleet manager the operational health of each aircraft. Instrumental neutron activation analysis (INAA) provides similar results and for a greater range of metals than the analytical techniques used in the field laboratories. However, for new oil-lubricated systems with fine filtration, the wear debris collects on the oil filter and little debris remains in the oil for analysis. The wear debris must be removed from the filter and ends up as a solid sample. Ultrasonic cleaning is used and the wear debris may be inspected qualitatively to determine the wear mechanism, termed Filter Debris Analysis (FDA). Quantitative analysis follows, termed Quantitative Filter Debris Analysis (QFDA) and, for techniques other than INAA, the sample must be dissolved. A combination of three acids and microwave digestion are then used. Then, to use the present field technique, this aqueous sample is then converted to an appropriate organic matrix before analysis. Again, INAA has been used to develop and monitor this QFDA technique for field application.