Science and Technology of Nuclear Installations

Volume 2014 (2014), Article ID 548672, 2 pages

http://dx.doi.org/10.1155/2014/548672

Editorial

Supercritical Water-Cooled Reactors

Jiejin Cai,¹ Claude Renault,² and Junli Gou³

¹Sino-French Institute of Nuclear Engineering and Technology, Sun Yat-sen University, Zhuhai, Guangdong 519082, China

²INSTN/PSNE, The French Alternative Energies and Atomic Energy Commission (CEA) Saclay, 91191 Gif-sur-Yvette, France

³School of Nuclear Science and Technology, Xi’an Jiaotong University, Xi’an, Shaanxi 710049, China

Received 24 July 2014; Accepted 24 July 2014; Published 18 August 2014

Copyright © 2014 Jiejin Cai et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Supercritical water-cooled reactor (SCWR) is the water-cooled reactor using supercritical pressure water as coolant [1]. It is considered as one of the promising Generation IV reactors, due to its advantages of plant simplification and high thermal efficiency [2, 3].

Several design concepts of SCWRs have been proposed: (a) supercritical water-cooled thermal neutron reactor; (b) supercritical water-cooled fast neutron reactor; (c) supercritical water-cooled mixed neutron spectrum reactor; (d) supercritical water-cooled pebble bed reactor; (e) supercritical heavy-water-cooled reactor. The detailed design parameters of some typical SCWR concepts around the world are summarized in Table 1 [4]. Recently, the use of thorium in the SCWRs has been investigated [5, 6].

Table 1: Some typical SCWR concepts around the world.

Name
Proposed by
Design concept
Moderate
Rated power (MW)
Outlet temperature (°C)
Pressure (MPa)
Net efficiency (%)

W21
Tokyo University
Thermal neutron spectrum SCWR
H₂O
1570
508
25
44

TWG1
Water TWG (Japan)
Fast neutron spectrum SCWR
H₂O
1728
Alternative
Alternative
38~45

W6-1
AECL (Canada)
CANDU-X-MARK1
D₂O
910
430
25
41

W6-2
CANDU-XNC
370
400
25
41

W6-3
CANDU-ALX1
950
450
25
40.6

W6-4
CANDU-X-ALX2
1143
650
25
45

—
Europe
HPLWR
H₂O
1000
500
25
44

—
INEL (USA)
Thermal neutron spectrum SCWR
H₂O
1600
500
25
44

B500SKD1
Russia
Integrative SCWR
H₂O
515
381
23.6
38

The advantages of the SCWRs are shown as follows [1].

(i)Supercritical water has excellent heat transfer properties allowing a high power density, a small core, and a small containment structure.(ii)The use of a supercritical Rankine cycle with its typically higher temperatures improves efficiency (would be ~45%).(iii)This higher efficiency would lead to better fuel economy and a lighter fuel load, lessening residual (decay) heat.(iv)SCWR is typically designed as a once-through, direct cycle, whereby steam or hot supercritical water from the core is used directly in a steam turbine, which makes the design simple.(v)Water is liquid at room temperature, cheap, nontoxic, and transparent, simplifying inspection and repair (compared to liquid metal cooled reactors).(vi)A fast SCWR could be a breeder reactor which could burn the long-lived actinide isotopes.(vii)A heavy-water SCWR could breed fuel from thorium (4x more abundant than uranium), with increased proliferation resistance over plutonium breeders.

Some challenges in SCWRs are the subjects of research work which need us to research, among which are the following [4–7].

(i)Lower water inventory (due to compact primary loop) means less heat capacity to buffer transients and accidents (e.g., loss of feedwater flow or large break loss of coolant accident) resulting in accident and transient temperatures that are too high for conventional metallic cladding.(ii)Higher pressure combined with higher temperature and also a higher temperature rise across the core result in increased mechanical and thermal stresses on vessel materials that are difficult to solve.(iii)The coolant greatly reduces its density at the exit of the core, resulting in a need to place extra moderator there.(iv)Extensive material development and research on supercritical water chemistry under radiation are needed.(v)Special start-up procedures are needed to avoid instability before the water reaches supercritical conditions.(vi)A fast neutron SCWR requires a relatively complex reactor core design in order to achieve a negative void coefficient.

In order to help readers understand the development of the SCWRs in the world, we sponsored a special issue on the supercritical water-cooled reactor and hoped to get some papers from the topics which include but are not limited to the following:

(i)reactor core and fuel designs,(ii)materials, chemistry, and corrosion,(iii)thermal-hydraulics and safety analysis,(iv)plant systems, structures, and components,(v)computational fluid dynamics (CFD) and coupled codes,(vi)neutronic properties,(vii)balance of plant,(viii)other applications.

Now the special issue is published, which includes 5 papers. The contents include a new concept of core design, like “A simplified supercritical fast reactor with thorium fuel,” calculation code development, like “Preliminary development of thermal power calculation code H-power for a supercritical water reactor,” “Code development in coupled PARCS/RELAP5 for supercritical water reactor,” and flow distribution, one of the important issues of thermal hydraulics in the nuclear reactor, like “Core flow distribution from coupled supercritical water reactor analysis.” It also contains some experimental results, like “Experimental investigation on flow-induced vibration of fuel rods in supercritical water loop.” We hope that readers of this special issue will find not only the development status of SCWRs and updated reviews on SCWRs, but also the formulation of important questions to be resolved such as how to develop the codes for SCWRs.

Jiejin Cai

Claude Renault

Junli Gou

References

Y. Oka, S. Koshizuka, Y. Ishiwatari, and A. Yamaji, Super Light Water Reactors and Super Fast Reactors, Springer, New York, NY, USA, 2010.

S. Liu and J. Cai, “Convergence analysis of neutronic/thermohydraulic coupling behavior of SCWR,” Nuclear Engineering and Design, vol. 265, pp. 53–62, 2013.

S. Liu and J. Cai, “Neutronic and thermohydraulic characteristics of a new breeding thorium-uranium mixed SCWR fuel assembly,” Annals of Nuclear Energy, vol. 62, no. 1, pp. 429–436, 2013.

X. Yang, G. H. Su, W. Tian, J. Wang, and S. Qiu, “Numerical study on flow and heat transfer characteristics in the rod bundle channels under super critical pressure condition,” Annals of Nuclear Energy, vol. 37, no. 12, pp. 1723–1734, 2010.

S. Liu and J. Cai, “Neutronics assessment of thorium-based fuel assembly in SCWR,” Nuclear Engineering and Design, vol. 260, pp. 1–10, 2013.

S. Liu and J. Cai, “Design & optimization of two breeding thorium-uranium mixed SCWR fuel assemblies,” Progress of Nuclear Energy, vol. 70, pp. 6–19, 2014.

Ph. Marsault, C. Renault, G. Rimpault, P. Dumaz, and O. Antoni, “Pre-design studies of SCWR in fast neutron spectrum: evaluation of operating conditions and analysis of the behavior in accidental situations,” in Proceedings of the International Conference of Asian Political Parties (ICAPP '04), Pittsburgh, Pa, USA, June 2004.