Feasibility of an Underground Nuclear Power Plant Based on Small Modular Reactors

The work presents a preliminary feasibility study of the construction of an underground Nuclear Power Plant (NPP), using a special Small Modular Reactors (SMRs) configuration [1].
With the increasing tension in the Middle East (ME), it is natural that part of the country`s energy assets will be placed underground to protect them against malicious acts. In addition, large accidents would result in no dispersal of radioactive materials above ground, and no adverse effects on public health or the environment. The power station chosen for this study was the SMR of mPowerTM [2] designed by the Babcock & Wilcox company, in cooperation with the Bechtel[3] company forming a joint venture by the name "Generation mPower"[2].
The necessary depth of the cavities and tunnels was calculated so that no weapon available presently or in the near future in the ME can damage any of the nuclear grade components. The second consideration to determine the depth of the cavities was that no radioactivity would escape to the surface in the improbable event of a core meltdown.
The present study is a follow up of the previous study on the feasibility of underground siting of a large NPP in Israel [4].
According to this study, the construction of the proposed power plant is feasible if medium or better rock quality can be found at the proposed site up to a depth of 150m. Major geo-technical aspects of the underground siting were evaluated in the study. The results of the study outline the desired depth for sufficient passive protection of the reactor against malicious acts. The geotechnical calculations of the strength and durability of the underground tunnels and caverns needed for the proposed plant were performed. Rock bolts and strand cables were included according to the rock quality assumed.
The Shivta-Rogem site was proposed in the past by the Israel Electric Company (IEC). For placing the plant underground different site considerations are necessary. At present, the deep rock characteristics of the underground of this site are only partly known from nearby geological studies. It is obvious therefore that there is a certain amount of uncertainty in the underground placement of the NPP at the proposed site. To reduce this uncertainty deep core drilling must be performed to evaluate the rock quality at the desired depth.
The combination of underground siting, small size and improved safety allows a significant decrease in the exclusion zone between the NPP and the nearby population centers.

References:
(1) D. Saphier, A. Rozen, A. Walter, A Preliminary Feasibility Study of the Underground Siting of the mPowerTM, in the Underground at the Shivta-Rogem Site. (in Hebrew) Internal Report, Ministry of Energy, to be published (2018).
(2) B. K. Arnholt, The B&W mPowerTM Small Modular Reactor I&C Design, Architecture and Challenges, Presentation, IAEA Technical Meeting May 23, (2013).
(3) B&W, Bechtel team up on mPower, World Nuclear News 14/7 (2010).
(4) D. Saphier, A. Rozen, I. Yaar, A. Walter, Feasibility of Underground Siting of a Large NPP in Israel. The 28th Conference of the Nuclear Societies in Israel, Tel-Aviv, Israel (2016).
(5) Centrale Nucleaire de Chooz, Wikipedia and other non-referenced internet sources and pictures.
(6) Krasnoyarks-26/Zeleznogorsk, Mining and Chemical Combine (MCA), www.globalsecurity.org/wmd/world/russia/krasnoyarsk-26_nuc.html.
(7) J.M.Miller, Incident at the Lucense Reactor. Nucl. Safety, 16, 1 (1975)
(8) Jeff A. Halfinger & Michael D. Haggerty, The B&W mPower™
Scalable, Practical Nuclear Reactor Design, Nuclear Technology, 178:2, (2012) 164-169

[*] This study was supported by the Ministry of Energy.