development of hot cells and their embedded parts

8/9/2019 Development of Hot Cells and Their Embedded Parts

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142 Special Issue | October 2014

BARC NEWSLETTERFounder’s Day

DEVELOPMENT OF HOT CELLS AND THEIR

EMBEDDED PARTS

K. Jayarajan, B. Sony, V.K. Shrivastava, R. Sahu, S. Panda, A.N. Jha, M.N. Rao

Division of Remote Handling and Robotics

Vivek Mahadev

Seismology Division

A.K. Pradhan

Isotope Application Division

S. Sethi, S.P. Dey, K. Karmakar, S.B. Gaikwad

Laser and Plasma Technology Division

V.R. Bhave, Kuldeep Sharma

Sealed Sources and Logistics, BRIT

Anwer Tariq

RAPP Cobalt Handling Facility, BRIT

Abstract

Hotcell facilities are used for handling radioactive materials for various applications, like waste management,

radioisotope production and post-irradiation examination. We have been involved in the development of hot cells,

water pools and associated equipments. Hot cell embedded parts like personal assess doors, external transfer

drawers, inter-cell transfer drawer, wall sleeves, plugs and hot cell liners play a major role in the operation of the

plant and safety of the operators. The article describes our recent experience in development of these components.

Shri K. Jayarajan is the recipient of the DAE Group Achievement

Award for the year 2012

Introduction

In nuclear industry, shielded nuclear radiationcontainment chambers are referred as hot cells. They

protect operators and the environment from the

harmful effects of radiation. Hot cell walls are made

from lead-bricks or from concrete. Thickness of the

concrete wall vary from 1 m to 2 m depending upon

the shielding requirements.

The walls and the floor of hot cells are embedded

with a variety of equipments or components.

Embedded parts (EPs), such as wall liners, wall sleevesand rails are static. However, EPs like access door,

inter-cell transfer drawer and external transfer drawer

contain heavy moving parts. These EPs maintains

shielding integrity during normal and accidentalconditions. Safety inter locks are provided on

dynamic EPs to avoid accidental exposure of radiation

to operator.

CCTV cameras or radiation shielding windows are

used for viewing the hot cell. Objects in the hot cells

are usually handled using general-purpose remote

handling tools like Master Slave Manipulators, Power

Manipulators and In-cell Cranes. Viewing systems and

remote handling tools are not in the scope of thearticle.

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Special Issue | October 2014 143


Recently, we have been involved in development of hot

cells and associated embedded parts for the following

facilities.

• Augmentation of Cobalt Handing Facility, Kota

(ACHF)

• Augmentation of Hotcell and Associated Facilities

for Radiation Technology Applications, Trombay

(AHCAFRTA)

• Integrated Facility for Radiation Technology, Vashi

(IFRT) and

• Uranium Clean-Up Facility, Trombay (UCUF).

In ACHF hot cells, the adjuster rods are processed to

recover cobalt-60 pencils and pellets for making sealed

sources. Fig.1 shows irradiated adjuster rod sub-

assemblies of power reactors placed in the RAPPCOF

Water Pool.

Fig. 1: Irradiated Adjuster Rod Sub-assemblies at RAPPCOF

Water Pool

Fig. 2 shows the plan view of a typical hot cell facility

indicating commonly used EPs. The hot cells (red

zone) are connected to the high bay area (green zone)

through isolation rooms (amber zone) as per radiation

zoning principle.

Fig. 3 shows the sectional end view of one of the hot

cells.

Fig. 2: Major EPs of a Typical Hot Cell (Top View)

Fig. 3 EPS and Remote Handling Tools of a Hot Cell (Side view)

Common Embedded Parts

Personal Access Door

Personal access doors are used for personnel entry into

the hot cell and for transferring radioactive materials

between the cold area and the hot cell in shielded

flasks. Access doors are of two types: hinged or sliding.

Fig. 4: Personal Access Door of ACHF, Kota at Fabricator’sShop


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144 Special Issue | October 2014


They may be motorised or manual. Mild steel doors

are designed to provide radiation-shielding equivalent

that of the concrete cell wall. Fig.4 shows the door

designed by us for ACHF, Kota. The mild steel door

weighing about 45 tons has a door flap thickness of

600 mm.

External Transfer Drawer

The external transfer drawer embedded in the

concrete wall is used for transferring materials into

the hot cell from outside and vice versa. It has two

shielded doors, a transfer drawer and mechanisms for

operating the doors and the transfer drawer. The doors

are mechanically interlocked to avoid simultaneous

opening of both doors.

Inter-cell Transfer Drawer

The inter-cell transfer drawer, embedded in the

common wall of adjacent hot cells, is used for

transferring materials from one hot cell to the other.It consists of an outer casing, two shielded doors, a

transfer drawer and remote mechanisms for operating

the doors and the drawer. The doors are mechanically

interlocked to avoid simultaneous opening of both

doors.

Service Sleeves and Plugs

For transmission of electric power, electric signal,

pneumatic supply, etc. across the hot cell walls, servicesleeves and plugs are provided on the walls. The plugs

are housed in the sleeves, which are embedded in

the wall. Their shapes are designed to avoid direct

radiation streaming.

Rails and Turntables

Active components are transferred between the water

pool and the hot cells in heavy shielded flask placed

on a trolley. Rails are laid on the floors of hotcell and

outside for transferring the trolley. Turntables are

provided at the junctions of the rails. The rails in the

hot cell are lined with stainless steel plates.

Hot Cell Liner

Walls and floor of the hot cells are lined with stainless

steel plates for easy decontamination. The stainless

steel plates are welded to the grid embedded in to the

wall or floor.

Water Pool Liner

Leak tightness is one of the major requirements of any

storage pool in a nuclear installation. As the first barrier

of leakage, the walls and the floors of the pools are

lined with stainless steel plates. The liner is designed

to withstand internal as well as external hydrostatic

pressure. Stringent quality control is implemented to

ensure leak tightness.

Lead Bricks

In place of concrete, mild steel encased lead bricks can

be used to construct the walls of a hot cell. Although

expensive, it will significantly reduce the thickness of

hot cell walls. To avoid radiation streaming, the bricks

are made with interlocking edges. Such lead bricks are

used in two wall of the alpha- beta- gamma shielded

hot cell of UCUF.

Conclusion

Embedded parts of hot cells play a major role in the

operation of the plant and safety of the operators. EPs

of our design are installed in the hot cells of AHCF,

ACHFRTA, IFRT and UCUF. ACHF is operational at

RAPPCOF, Kota. It has been producing and supplying

Industrial Irradiator Sources and Tele-therapy Sources

of cobalt-60.

development of hot cells and their embedded parts

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