Outline of Joyo restoration work

Experimental Fast Reactor Joyo

Oarai R&D Center, JAEA

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Outline of Joyo

restoration work

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Background

Hold

down

shaft

Lower part of UCS

Fiber

scope

Bent irradiation

test S/A

(MARICO-2) Top of S/As

MARICO-2 : Material

testing rig with

temperature control

IVS : In-vessel storage

rack

IVS

The top of irradiation

test subassembly

(S/A) “MARICO-2” had

bent onto the IVS.

“MARICO-2” had

damaged the upper

core structure (UCS).

This incident requires replacement of UCS and retrieval of

MARICO-2 S/A for Joyo re-start 3

Cask

(2) Retrieval of

ed-UCS

Door valve

(3) Retrieval of

MARICO-2 S/A

(4) Installation of

n-UCS

L-R/P

S-R/P Temporary pit cover

Screw jack-up equipment

Guide tube

(1) Jack-up of

ed-UCS

UCS

Cask

MARICO-2

S/A

MARICO-2 S/A retrieval equipment

Wire jack-up equipment

Ed-UCS is extracted through

small-diameter part.

UCS

Outline of restoration work plan

Plant condition :

- Fuel S/As are remained in reactor vessel.

>>> Sodium level is maintained at 50 mm below top of fuel S/A.

- Temperature of sodium is approximately 200deg-C, and temperature of

cover gas is approximately 140~160deg-C.

ed-UCS : existing damaged UCS

n-UCS : new UCS

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Joyo restoration work plan

2011 2012 2013 2014 2015

Manufacturing of new UCS

Full ex-vessel test

Manufacturing of MARICO-2 subassembly retrieval equipment

Replacement of UCS

Retrieval of MARICO-2 subassembly

Ex-vessel test of jack-up equipment

Manufacturing of jack-up equipment

Manufacturing of cask, door-valve etc.

Full ex-vessel test

Detaching of equipment on R/P Re-installation of equipment on R/P

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On-site preparation work

for Joyo restoration

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1. Arrangement of R/P position

> Large R/P : 254deg.

> Small R/P : 115deg.

2. Detaching of equipment on R/P

（jacked-down at position as mentioned above）

3. Others

> Reactor is shut down

- Control rod : Inserted into core

- Control rod driving mechanism : Detached for maintenance

> As fuel S/As are remained in reactor vessel, primary sodium

coolant retained in reactor vessel.

* Sodium level is maintained GL-9540 (50 mm below top of fuel

S/A) ~ GL-6100 (normal level) as required in maintenance.

* To avoid contact, ed-UCS cannot be set just

above MARICO-2 S/A.

( Retrieval is performed using hole through

which ed-UCS is extracted )

On-site preparation work

for Joyo restoration Large R/P

Small R/P

MARICO-2 S/A

UCS

Location of R/P

during restoration work

Retrieval

equipment

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Ex. : Detaching of equipment on R/P

Upper : Door-valve on fuel handling hole

Lower : Hold-down shaft driving mechanism

UCS

[ Objectives of detaching of equipment on R/P ]

> To secure area for UCS removal and installation

(Detaching door-valve on fuel handling hole / hold-down shaft driving

mechanism / door-valve on inspection hole (A) )

> To secure working area (Detaching surrounded equipment)

Temporary cover

Door-valve on

inspection hole (A)

Before After

Temporary door-valve

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Ref. Structure of R/V, R/P and UCS

Small R/P

Large R/P

UCS

Core

R/V

R/V

inlet

R/V

outlet

IVS

Inspection hole (B)

Fuel handling hole

Inspection hole (A)

One center hole

and ten control rod holes

Control rod

upper guide tube

Thermo-couple

sleeves

Sodium flow

regulating grid

Control rod 9