Development of Technologies and Safety Systems for Pressurized Heavy Water Reactors in India

2017 ◽  
Vol 3 (2) ◽  
Author(s):  
S. Banerjee ◽  
H. P. Gupta

The technology of pressurized heavy water reactors (PHWRs) which was developed with prime objectives of using natural uranium fuel, implementing on power fuelling, utilizing mined uranium most effectively, and achieving excellent neutron economy has demonstrated impressive performance in terms of high capacity factors and an impeccable safety record. The safety features and several technology advancements evolved over the years in which Indian contributions that are considerable are briefly discussed in the first part of the paper. Unique features of PHWR such as flexibility of fuel management, distribution of pressure boundaries in multiple pressure tubes (PTs), and a large inventory of coolant-moderator heat sink in close proximity of the core provide inherent safety and fuelling options to these reactors. PHWRs, in India have demonstrated to have the advantage of lower capital cost per megawatt even in small size reactors. Low burn up associated with natural uranium fuel, higher level of tritium in the heavy water coolant, and a slightly positive coolant void coefficient in present generation PHWRs have all been addressed in the design of advanced heavy water reactor (AHWR). The merit of adopting closed fuel cycle with partitioning of minor actinides in reducing the burden of radio-toxicity of nuclear waste and of deploying light water reactors (LWRs) in tandem with PHWRs in the evolving nuclear fuel cycle in India are also discussed.

Author(s):  
A. K. Nayak ◽  
S. Banerjee

The pressurized heavy water reactor (PHWR) technology was conceived in Canada and has moved to several nations for commercial production of electricity. Currently, 49 power reactors operate with PHWR technology producing nearly 25 GWe. The technology is flexible for adopting different fuel cycle options which include natural uranium, different mixed oxide (MOX) fuel, and thorium. The technology has made substantial improvement in materials, construction, and safety since its inception. PHWRs have demonstrated excellent performance historically. Their safety statistics are excellent. Indian PHWRs also have shown economic competitiveness even in small sizes, thus providing an ideal design for new entrants. While the technology features of PHWRs are available even in textbooks, the objective of this paper is to highlight the historical development and salient features, and innovations for further improvement in operation, safety and economics. Thus, this paper shall serve as a curtain raiser for the special issue “Pressurized Heavy Water Reactors (PHWRs) Safety: Post Fukushima.”


2018 ◽  
Vol 7 (2) ◽  
pp. 147-155 ◽  
Author(s):  
Michael McDonald ◽  
Megan Moore ◽  
Dan Wojtaszek ◽  
Nicholas Chornoboy ◽  
Geoffrey Edwards

An incremental approach to introducing thorium to the conventional pressure-tube heavy-water reactor natural uranium fuel cycle is investigated. The approach involves the replacement of the centre fuel element of the bundle with an element of thorium dioxide. Increasing the operating margin of a key safety parameter, the coolant void reactivity, is a prime motivating factor. The analyses showed that the simple use of a single pin of thorium is unlikely to be economically advantageous due to a large burnup penalty and increased fuel costs. However, a slight reduction in the void reactivity is observed, and this approach does allow the exploitation of the energy potential available in thorium as an alternative nuclear fuel resource through the development of a U-233 resource. This bundle concept may also be advantageous from a fuel disposal point of view, as the fuel requires less time in storage before emplacement in a deep geological repository.


2015 ◽  
Vol 68 (3) ◽  
pp. 566-572 ◽  
Author(s):  
S. C. Xiao ◽  
Jing Zhao ◽  
X. Heng ◽  
X. Y. Sheng ◽  
Z. Zhou ◽  
...  

Author(s):  
Romney B. Duffey

Nuclear energy must be made available, freely and readily, to help meet world energy needs. The perspective offered here is a model for others to consider, adopting and adapting using whatever elements fit their own strategies and needs. The underlying philosophy is to retain flexibility in the reactor development, deployment and fuel cycle, while ensuring the principle that customer, energy market, safety, non-proliferation and sustainability needs are all addressed. Canada is the world’s largest exporter of uranium, providing about one-third of the world supply for nuclear power reactors. Canada’s Atomic Energy of Canada Limited (AECL) has developed a unique world-class nuclear power reactor technology — the CANDU® reactor based on the Pressure Tube Reactor (PTR) concept, moderated by heavy water (D2O), also sometimes called the Pressurized Heavy Water reactor or PHWR. With expectations of significant expansion in nuclear power programs worldwide and the resultant concerns about uranium availability and price, there is a growing desire to improve resource utilization by extracting more energy from each tonne of mined fissionable material. Attention is therefore being increasingly focused on fuel cycles that are more energy efficient, reduce waste streams and ensure sustainable futures. There are also many compelling reasons to utilize advanced fuel cycles in PTR (CANDU-type) thermal spectrum reactors. Because of its inherent technical characteristics, PTRs have a great deal of fuel cycle flexibility. The combination of relatively high neutron efficiency (provided by heavy water moderation and careful selection of core materials), on-line fuelling capability and simple fuel bundle design mean that PTR reactors can use not only natural and enriched uranium, but also a wide variety of other fuels including thorium-based fuels and those resulting from the recycle of irradiated fuel. In addition, the PTR can be optimized as a very effective “intermediate burner” to provide efficient fuel cycles that remove residual minor actinides. This inherent fuel cycle flexibility offers many technical, resource and sustainability, and economic advantages over other reactor technologies and is the subject of this paper. The design evolution and intent is to be consistent with improved or enhanced safety, licensing and operating limits and global proliferation concerns, and sustainable energy futures.


2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Jawad Haroon ◽  
Leslie Kicka ◽  
Subhramanyu Mohapatra ◽  
Eleodor Nichita ◽  
Peter Schwanke

Deterministic and Monte Carlo methods are regularly employed to conduct lattice calculations. Monte Carlo methods can effectively model a large range of complex geometries and, compared to deterministic methods, they have the major advantage of reducing systematic errors and are computationally effective when integral quantities such as effective multiplication factor or reactivity are calculated. In contrast, deterministic methods do introduce discretization approximations but usually require shorter computation times than Monte Carlo methods when detailed flux and reaction-rate solutions are sought. This work compares the results of the deterministic code DRAGON to the Monte Carlo code Serpent in the calculation of the reactivity effects for a pressurized heavy water reactor (PHWR) lattice cell containing a 37-element, natural uranium fuel bundle with heavy water coolant and moderator. The reactivity effects are determined for changes to the coolant, moderator, and fuel temperatures and to the coolant and moderator densities for zero-burnup, mid-burnup [3750  MWd/t(U)] and discharge burnup [7500  MWd/t(U)] fuel. It is found that the overall trend in the reactivity effects calculated using DRAGON match those calculated using Serpent for the burnup cases considered. However, differences that exceed the amount attributable to statistical error have been found for some reactivity effects, particularly for perturbations to coolant and moderator density and fuel temperature.


2017 ◽  
Vol 4 ◽  
Author(s):  
Anshu Bharadwaj ◽  
Lakshminarayana Venkat Krishnan ◽  
Subramaniam Rajagopal

ABSTRACTNuclear power is a crucial source of clean energy for India. In the near-term, India is focusing on thermal reactors using natural and enriched uranium. In the long-term, India is exploring various options to use its large thorium reserves.India’s present nuclear installed capacity is 5680 MW, which contributes to about 3.4% of the annual electricity generation. However, nuclear power is an important source of energy in India’s aspirations for energy security and also in achieving its Intended Nationally Determined Contributions (INDC), of 40% fossil free electricity, by 2030. India has limited uranium reserves, but abundant thorium reserves. The Nuclear Suppliers Group (NSG) lifted restrictions on trade with India, in 2008, enabling India to import uranium (natural and enriched) and nuclear reactors. In the near–term (2030), the nuclear capacity could increase to about 42,000 MW. This would be from a combination of domestic Pressurized Heavy Water Reactors (PHWR) and imported Pressurized Water Reactors (PWR). For the long–term (2050), India is exploring various options for utilising its vast thorium reserves. This includes Advanced Heavy Water Reactor and Molten Salt Breeder Reactor. However, generating public acceptance will be crucial to the expansion of the nuclear power program.


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