JPS63305296A - Tritium remover - Google Patents

Abstract

PURPOSE:To enable the obtaining of a reliable tritium remover with a simple handling, by using a hydrogen occlusion alloy to remove tritium as radiation element. CONSTITUTION:A primary system coolant of a nuclear reactor 1 exchanges heat with a secondary system coolant by an intermediate heat exchanger 2 and the secondary system coolant exchanges heat with steam by a steam generator 3. In this system, tritium existing in a primary system shifts to a cover gas system of the nuclear reactor 1 to be removed with a primary system cold trap 5 provided on an overflow tank 4. Tritium existing in a secondary system is removed with a secondary system cold trap 6. Then, H2 and tritium are introduced to a liquefaction distiller 7 by heating the cold traps 5 and 6 and after the separation of isotope, tritium is introduced to a stainless container 8 holding a sponge of Zr as hydrogen occlusion alloy to remove.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a device for removing lithium generated in a fast breeder reactor.

(Prior Art) Tritium contamination is becoming a problem due to nuclear tests and releases from nuclear power plants and nuclear fuel reprocessing facilities. The problem with tritium is tritium water (Hl).
This is because it is easily taken into the human body as O) and becomes a source of internal radiation exposure.

In fast breeder reactors, tritium is also produced by the triple nuclear fission reaction in the fuel and the neutron reaction in boron in the control rods.

Produced by neutron reactions of lithium contained in fuels and coolants. The tritium produced by these reactions diffuses through the fuel rods and control rods and moves into the primary system. And the first part is mid-term heat exchange! The fji unit is diffused and transferred to a secondary system.

Tritium present in the primary system may be transferred to the cover gas system, removed from a cold trap, or diffused through sodium or gas pipes to exit. 2
The tritium present in the next system migrates to the cover gas system, is removed by a cold trap, goes out through the sodium and gas system piping, and diffuses through the steam generator heat exchanger tube and exits into the environment. There are things etc.

(Problems to be Solved by the Invention) However, 90% of the generated gas is captured by the primary and secondary cold traps. Therefore, since tritium is generated along with hydrogen during cold trap regeneration, it is necessary to take measures to prevent it from being released into the atmosphere. Normally]-Remove 1~Rib Kumu in Rudo Trap Regeneration 04. Iris oxidizes gaseous tritium and produces 1
~ There is a method of recovering it as ribum water, but
A method that is easy to handle and reliable has been desired.

The purpose of Mizuzadeaki is to develop a technique for removing tritium, which is the source of the qLJ line, using a hydrogen storage alloy.

[Configuration 1 of the Invention (Means for Solving Problems) The tritium removal device of the present invention includes 15 tritium removal systems using hydrogen storage alloys.

(Function) Hydrogen storage alloys undergo a reversible reaction in the form of metal hydrides.
-12, D2, and T2 are occluded and released. When kept at a low temperature, hydrogen storage alloys do not generate heat and store 1-12 gases until the hydrogen storage pressure peak corresponding to the hydrogen partial pressure is reached.
When kept at a high temperature, it absorbs heat and releases l-12.

Therefore, instead of using the metal trap 12, tritium can be removed by pouring tritium into the hydrogen storage alloy while keeping the temperature at a low temperature during regeneration of the hydrogen storage alloy.

In the present invention,
It is possible to construct a device as long as 11 ゛h.

(Example) The present invention will be explained below with reference to FIGS. 1 and 2.

First, we received the system diagram of the high-speed increase reactor. The secondary cold 7JI material exchanges heat with steam in the steam generator 3, and the generated hot air is sent to the steam turbine.

In this system, lithium present in the primary system moves to the cover gas system of the reactor 1 and is removed by the primary system coult 1 to lap 5 provided in the A-bar flow tank 4. Further, tritium present in the secondary system is removed by a secondary system cold trap 6 provided in the secondary system.

The present invention relates to a tritium removal device that removes tritium during regeneration in these cold traps 5 and 6. In other words, the tritium removal device of the present invention is a combination system of cold traps 5 and 6, a liquefaction distiller 7, and a tritium trap 8 made of 5US304 containing a sponge of Zi, which is a hydrogen storage alloy, as shown in FIG. It is configured.

The i~ lithium removal device of the present invention utilizes the following properties of the hydrogen storage alloy. In other words, the hydrogen storage alloy is a metal hydride in the form of 1-12, D2, as shown by the following reversible equation.
, occludes and releases T2 [1 quality].

This will be explained below in sections 1-12.

~1-t H2M to1 +△Q
... (1) Here, M: Hydrogen storage alloy MHx: Metal hydride △Q: Heat of reaction At this time, between the equilibrium dissociation pressure and the temperature, RTen PH27△T1-T-△S-
(2) holds true.

Here, PH2: Equilibrium dissociation pressure △[-1: Enthalpy of formation of metal hydride ΔS: Entropy R: Gas constant T: Temperature In hydrogen storage alloys, △H<O, △S>O, so if the alloy is kept at a low temperature, it generates heat. From then on, it stores l-+2 gas until it reaches a hydrogen storage pressure corresponding to the hydrogen partial pressure, and when the temperature is raised, it absorbs heat and releases 12 gas.

For example, when using uranium as a hydrogen storage alloy, 2U + 3T
2 2UT3 j! n P(atm) =-4,537/T+7.03
=13) In Fig. 1 again, by heating the cold trap 5.6, tritium 12,1~lithium is introduced into the liquefaction distiller 7, and after isotope separation, tritium is transferred to a Zr sponge, which is a hydrogen storage alloy. Included S U
It is led to a container 8 made of S 304. In this container 8, the equilibrium dissociation pressure of U and T3 at the highest temperature is 6x1o-b from equation (3).
Since it is very small atm, it is desirable to store T2 from the point of view of tiIlrJJ line management. Also, UT3 is 500 yen
Since tritium can be extracted at 1 atm at °C, there is no need to worry about 1-lithium during recovery.

As hydrogen storage alloys, T; , ;lr , Zl-(N;
XMr+ 1-X ) 2 can also be used. The temperature at which tritium is absorbed is higher than U. For example 7
In the case of 1-, a temperature of 600°C or more is required.

[Effects of the Invention] As described above, in J3 of the present invention, by using a hydrogen-absorbing metal to remove tridicum, which is a radioactive element,
You can use tritium removal equipment, which is easy to handle and reliable.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the tridium removal head according to the present invention, and FIG. 2 is a system diagram of a fast breeder reactor. 1... Nuclear reactor, 2... Intermediate heat exchanger 3...
・Steam generator 4...Overflow tank 5...-Secondary system cold trap 6...Secondary system] - Ruto trap 7...Liquification pre-reservoir ε3...Tritium trap Agent Patent attorney Nori Chika Yudo Ken Daishimaru Ken 5.6 Figure 1 Figure 2

Claims (1)

[Claims] (1) A tritium removal device characterized in that a hydrogen storage alloy is used to remove tritium during cold trap regeneration connected to the primary and secondary coolant systems of a nuclear reactor.