on page 23, third paragraph, 3rd sentence of Section 2.3 Material Selection and Irradiation Testing of "Development of NRU Reflector Wall Inspection System", the radiation tolerance of Delrin should be printed as "10 4 Gy" and not "104 Gy", and in the 6th sentence the radiation tolerance of PEEK should be printed as "10 7 Gy" and not "107 Gy".

This paper describes an experimental approach where reactor kinetics experiments are used to study reactor physics phenomena that are normally investigated using static-measurement techniques. This approach provides validation data relating to these phenomena for a range of core reactivities, rather than only providing data at critical conditions. Sub-critical and super-critical transient measurements were performed in the ZED-2 reactor. The transients were analyzed using a point kinetics model to derive the reactivity states that induced the transients. The reactor physics phenomenon of interest for the current study is Coolant Density Induced Reactivity. Initial measurements were performed using an air-cooled (i.e., voided) ZED-2 lattice; the measurements were then repeated using the same lattice cooled with light water. These measurements yielded reactivity values for both coolant conditions in the lattice for a range of super-critical and sub-critical states. This investigation avoids the inherent assumption of static-measurement analyses that the bias in predicting criticality for the two coolant conditions is identical to the bias in predicting the phenomenon of Coolant Density Induced Reactivity itself. The measured reactivity values are compared with calculations employing the 3-D stochastic neutron transport reactor code MCNP.

There is a growing international interest in using coupled, multidisciplinary computer simulations for a variety of purposes, including nuclear reactor safety analysis. Reactor behaviour can be modeled using a suite of computer programs simulating phenomena or predicting parameters that can be categorized into disciplines such as Thermalhydraulics, Neutronics, Fuel, Fuel Channels, Fission Product Release and Transport, Containment and Atmospheric Dispersion, and Severe Accident Analysis. Traditionally, simulations used for safety analysis individually addressed only the behaviour within a single discipline, based upon static input data from other simulation programs. The limitation of using a suite of stand-alone simulations is that phenomenological interdependencies or temporal feedback between the parameters calculated within individual simulations cannot be adequately captured. To remove this shortcoming, multiple computer simulations for different disciplines must exchange data during runtime to address these interdependencies. This article describes the concept of a new framework, which we refer to as the “Backbone,” to provide the necessary runtime exchange of data. The Backbone, currently under development at AECL for a preliminary feasibility study, is a hybrid design using features taken from the Common Object Request Broker Architecture (CORBA), a standard defined by the Object Management Group, and the Message Passing Interface (MPI), a standard developed by a group of researchers from academia and industry. Both have well-tested and efficient implementations, including some that are freely available under the GNU public licenses. The CORBA component enables individual programs written in different languages and running on different platforms within a network to exchange data with each other, thus behaving like a single application. MPI provides the process-to-process intercommunication between these programs. This paper outlines the different CORBA and MPI configurations examined to date, as well as the preliminary configuration selected for coupling 2 existing safety analysis programs used for modeling thermal–mechanical fuel behavior and fission product behavior respectively. In addition, preliminary work in hosting both the Backbone and the associated safety analysis programs in a cluster environment are discussed.

The concept of “disruptive innovation” is a management tool that provides a framework for understanding the structure and dynamics of technology markets, especially their sometimes acute response to innovation. The concept was used in a preliminary assessment of a number of energy technologies, including renewable energy technologies and energy storage, as well as nuclear technologies, as they interact in industry and the marketplace. The technologies were assessed and perspectives were provided on their current potential for innovation to disrupt the value networks behind electricity markets. The findings indicate that this concept may provide useful guidance for the planning of technology development.

Snow washout ratios (WR) for carbon-14 (C-14) and tritiated water vapour (HTO) have been evaluated. Following the establishment of an efficient methodology for handling environmental (small) levels of C-14, WR for C-14 was calculated for the first time (but in a single experiment), with resulting WRC-14 = 3.159 ± 1.396. During 2004–2010 the WR for HTO has been measured in a broad range of meteorological conditions resulting in an average WRHTO = 0.251 ± 0.369. WRHTO has been further analyzed with respect to independent environmental parameters (drivers). No correlation of the WRHTO with precipitation intensity has been observed. A simple empirical relationship between WRHTO and temperature, atmospheric stability and surface roughness was established.

Mercuric (Hg) nitrate is used as a catalyst in the medical isotope production process at Atomic Energy of Canada Limited (AECL) Chalk River Laboratories (Chalk River, ON) to ensure consistent Mo-99 target dissolution. The subsequent high level radiological liquid waste is cemented into stainless-steel pails and shipped to a waste management area for long-term storage. Previous studies have confirmed that Hg tends to bind and precipitate I-131, thus minimizing its release to the environment. In order to assess the situation and evaluate the need for Hg monitoring, environmental media (vegetation, surface soil, groundwater, and air) surrounding this waste storage area were sampled and results were compared with applicable guidelines and/or background areas at AECL and other locations.Mercury in groundwater, surface soil, and vegetation were found to be below applicable environmental guidelines and comparable to background locations. Atmospheric Hg near waste storage was found to be elevated above background, but well below applicable guidelines for continuous monitoring. Concentrations of Hg in air also dissipated quickly and were comparable to background within 60 to 80 m from source.The atmospheric Hg monitor used in this study (TEKRAN 2537B) constitutes part of the custom-built portable TEAMS trailer that was designed to provide Chalk River Laboratories with the capability to measure, monitor and model Hg emissions, along with other radiological and non-radiological contaminants, for a wide range of situations. The trailer can also be easily re-configured to adapt to different monitoring needs.

As Ottawa River contamination is historical and resides in sediment, ecological risk and trophic transfer depend on linkages between sediment and biota. One of the ways in which this linkage is quantified is through the use of the biota sediment accumulation factor (BSAF). In this study, we present the first field estimates of BSAF for a number of radionuclides. The strongest and most consistent BSAFs were those for 137Cs in deposit feeding taxa, suggesting that sediment concentrations rather than dissolved concentrations drive uptake. For crayfish and unionid bivalves that do not feed on sediment, biota radionuclide concentrations were not related to sediment concentrations, but rather reflected concentrations in water. BSAFs would not be appropriate for these non-deposit feeding biota. BSAFs for 137Cs were not significantly different among deposit feeding taxa, suggesting similar processes for ingestion, assimilation and elimination. These data also show that the concentration factor approach used for guidance would have led to spurious results in this study for deposit feeding benthic invertebrates. Concentrations of 137Cs in Hexagenia downstream of the CRL process outfall range by about 2-orders of magnitude, in comparison to relatively uniform water concentrations. The concentration factor approach would have predicted a single value downstream of CRL, underestimating exposure to Hexagenia by almost 2-orders of magnitude at sites close to the CRL process outfall.

In 2009 May, the National Research Universal (NRU) calandria leaked. During the next year, the calandria was inspected with six new Non-Destructive Evaluation (NDE) techniques to determine the extent of the corrosion, repaired, and finally the repair was inspected with four additional new NDE techniques before the reactor was returned to service.The calandria is surrounded by a light-water reflector vessel fabricated from the same material as the calandria vessel. Concerns that the same corrosion mechanism had damaged the reflector vessel led to the development of a system to inspect the full circumference of the reflector wall for corrosion damage. The inspection region could only be accessed through 64 mm diameter ports, was 10 m below the port, and had to be inspected from the corroded surface. The ultrasonic technique was designed to produce a closely spaced wall thickness (WT) grid over an area of approximately 5 m2on the corroded surface using a very small probe holder.This paper describes the Reflector Wall Inspection (RWI) development project and the system that resulted.

Monte Carlo simulations are applied to the full-reactor analysis of the SLOWPOKE design. The temperature reactivity feedback calculated by using the MCNP code for either the high enriched uranium (HEU) or low enriched uranium (LEU) core is in good agreement with the experimental data, with a k-eff bias of +3.3 mk for a HEU core and +6 mk for a LEU core. Two methods that are based on existing third-party codes have been developed for use in core following: 1) MCNP (for the transport calculation) in conjunction with WIMS-AECL (for fuel burnup advancement), and 2) SERPENT (that combines both transport and burnup capabilities). Both methods show very good agreement with the experimental data for core excess reactivity and detailed power distributions versus burnup and reactivity shim.

The Ottawa River has received nuclear reactor effluent from Chalk River Laboratories (CRL) for more than 60 years, including releases from a NRX accident in 1952. Recent interest in the potential impact of these historical releases and the possible need for remediation of a small region immediately downstream from the release point has led to comprehensive studies to assess risk to people and wildlife. In this paper, the results of an extensive survey of gamma-emitting anthropogenic radionuclides in Ottawa River sediment in the vicinity of CRL are presented. Anthropogenic radionuclides detected in Ottawa River sediment include 60Co, 94Nb, 137Cs, 152Eu, 154Eu, 155Eu and 241Am. Concentrations of all anthropogenic radionuclides decline rapidly with distance downstream of the process outfall, reaching stable concentrations about 2 km downstream. All of these radionuclides are found at some sites within 2 km upstream of the process outfall suggesting limited upstream transport and sedimentation. Comparison of anthropogenic radionuclides with several representative primordial radionuclides shows that with the exception of sites at the process outfall and within 2 km downstream of the process outfall, primordial radionuclide concentrations greatly exceed CRL derived anthropogenic radionuclide concentrations. Thus, over 60 years of radionuclide releases from operations at CRL have had little impact on radionuclide concentrations in Ottawa River sediment, except at a few sites immediately adjacent to the process outfall.