P001 Deep-Sea Fast Reactors Demanded for Oceanography

A0001 Akira Otsubo Japan Nuclear Cycle Development Institute

Growing activities in the sea require development of a long life power unit.

A report[l] was written on therequirement of electric power source for oceanography.

Oceanographers demand the electric power sources of several dozen to several

hundreds kilo watts for sea bottom bases. In this report, the electric power sources were

studied by using the concept of deep sea fast reactor (DSFR) which was explained in the

2000 international symposium of underwater technology. The DSFR consists of a liquid

fast reactor (LMFR) system and a closed Brayton cycle (CBC) power generation system.

A conceptual design study was performed on the DSFRs of 40, 200 and 500kWe.

Main specifications of them are as follows.

I ry system Coolant; NaK, Coolant temperatures; 650/550C at reactor outlet/inlet, Fuel;

UN/MN/U02/MOX, Cladding! structural material; Hasteloy N/ stainless steel.

2ry system Coolant; Mixture gas of He and Xe, Gas temperature; 635C at turbine inlet & 60C

at cooler outlet.

Pressure hull (40k We) 2 sphere type, Inner diameter; 2.92m, Material; Titanium alloy.

(200kWe) 2 sphere type, Inner diameter; 3.50m, Material; High tensile steel.

(500kWe) 3 sphere type, Inner diameter; 3.50m, Material; High tensile steel.

Seawater flow (40kWe & 200kWe) natural convection, (500kWe) forced convection.

The relation between the depth of sea bottom to set the DSFR and its weight is as follows.

Depth m 1000 2000 3000 4000 5000 6000

Weight (40kWe) ton 17.8 22.0 25.2 27.9 30.3 32.5

do. (200kWe) ton 33.4 42.0 48.6 54.2 59.1 63.6

do. (500kWe) ton 43.8 56.7 66.7 75.0 82.4 89.1

Recently, the non-proliferation problem of nuclear fuel has become to be discussed more

definitely step by step. In this report, the problem was also studied about the fuel in the

DSFR on the basis of the latest knowledge. When the mixed fuel of plutonium and uranium

is used, the DSFR might be considered to have the same capability for the non-proliferation

problem as an usual light water reactor.

Finally naval reactors for fighting ships were studied to show that the total power of the naval

reactors is extremely large compared with that of the DSFR proposed here. Peaceful use

of nuclear power is expected to be done more and more in the Ocean.

[l] The report was performed in Japan Atomic Energy Research Institute (JAERI).

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