LLW TRANSPORT BY IP-2 PACKAGING K. TANAKA

Nuclear Fuel Transport Co. Ltd, Tokyo, Japan

Abstract

As the Japanese nuclear power plants are located on the sea coast, optimal system of the LLW transport consists of sea and land modes. A special ship "Seiei Maru" was built to transport the LLW from nuclear power paints to the LLW Burial Center in Rokkasho—mura, Aomori Prefecture and dedicated trucks were prepared to transfer the LLW from the receiving wharf to the Burial Center. Containers were developed to efficiently transport LLW drums and were designed and tested to meet the IP—2 packaging requirements. 3,000 units of such containers have been used since 1992 and the safe transport of LLW has been demonstrated by means of the IP—2 packagings.

1. Introduction

In Japan 46 nuclear power plants are in operation at 17 sites and about 30 per cent of electric power is supplied by these plants.

Low level wastes (LLW) generating at the nuclear power plants are packaged in 200 litre drums and temporarily stored in the on-site storehouse. The number of these drums accumulated so far amounts to approximately 480 thousands.

In December 1992 the LLW Burial Center was established at Rokkasho-mura, Aomori Prefecture, as one of the nuclear fuel cycle facilities to receive the LLW drums for shallow land disposal.

The capacity of the LLW Burial Center is 200,000 drums for the first stage ofconstruction and the object of burial is at present low level wastes which have been solidified homogeneously by cement and asphalt.

The transport of these wastes from power plants to the LLW Burial Center is performed by the Nuclear Fuel Transport Co., Ltd. (NFT), and the mode of the transport is a combination of sea and land transports.

The packagings used are special enclosed containers which are able to contain 8 drums. They were developed by NFT and were confirmed to meet all the requirements for the IP—2 packaging by various tests which had been performed during the R&D stage.

The sea transport is serviced by a special dedicated ship which is able to carry 384 packages per voyage and the land transport is performed by trucks which carry 2 packages per truck.

More than one year has already passed since the first shipment was made and safe and trouble free operation has been performed.

2. Outline of the transport system

The LLW drums stored at the power plants are contained in the IP—2 packagings after they are confirmed to meet the burial requirements by Wastes Confirmation Inspection.

Then they are transferred by trucks to the dedicated port or near—by commercial port of the nuclear power plant.

All the Japanese nuclear power plants are located on the seashore and mostly provided with their own ports for 3,000-ton—class ships. Therefore sea transport is convenient for the LLW shipment in Japan (Fig.l, Fig.2).

The special dedicated ship "Seiei Maru", which was constructed to transport LLW has the dead weight of approximately 3,000 tons and is provided with concrete shield against radiation. In 7 cargo holds of the ship the cell guides are installed to meet the size of the packages so that they are surely stowed in the cargo holds (Fig.3).

Tomirl-HokkBldo EPCO

G*nh«l-Kyu*hu EPCO

Stndftl-Kyushu EPCO

Fig.l Location of Nuclear Power Plants in Japan

The Seiei Mam is installed with the on-board bridge crane which is used for loading and unloading of packages at the ports of nuclear power plants.

The Seiei Maru leaving the port of a power plant arrives in 2 to 5 days at the Mutu-Ogawara Port (M.O. Port) which is located at Rokkasho—mura, Aomori Prefecture.

The M.O. Port is a public port under the control of Aomori Prefecture. An NFT s bridge crane of 25-ton lifting capacity is installed at the wharf of the port (Fig.4) In order to open the wharf for the public use the crane is moved to the parking lot on a curved track when it is not used for LLW operations.

The wharf crane as well as on-board crane has a remote and semi—automatic control system to reduce the radiation exposure of the operators.

The packages in the ship holds are lifted up by the wharf crane, two at a time, and loaded to the exclusive use trucks which are standing by at the wharf.

The dedicated trucks are standard 11—ton trucks of which beds are partially remodelled and the tie—down and the releasing operations of the packages can possibly be done remotely at the driver' s seat (Fig.5).

The distance of the land transport is about 9 km, most of which is on—site road of the Japan Nuclear Fuel Limited (JNFL) who owns the LLW Burial Center. However, as the trucks should partly cross the public road, it is necessary before shipment to

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Cannot QuM*c m«f*

LLW Slorjgt Cinur

Fig.2 LLW Transport System in Japan

Radar

Packagings

Double Hull on Bolh Side*

• Double Bottom

Fig.3 The Special Dedicated Ship "Scici Maut"

Fig.4 Bridge Crane at the Receiving Wharf

measure the radiation dose rates and confirm that they are below the regulatory limits, i.e. 2 mSv/h at the surface of the truck and 0.1 mSv/h at 1 meter therefrom.

To automatically measure the dose rates and reduce the exposure, a device which is called "Gate Monitor" was developed and the measurement at 21 points is able to be completed in a very short period of time, namely, in approximately 4 minutes (Fig.6)

Packaging Riling Guide

Filling Device (Twisl lock) Packaging

ABS, AS R i

Fig.5 The LLW Transport Truck

Operator's seat

LLW packages Rear radiation monitor

Vehicle operation Indicator lamps

Lateral radiation monitor Transport veNcle

Fig.6 Gate Monitor

The trucks arriving at the LLW Burial Center are released of their packages which are then delivered to the JNFL. The packages are opened by the JNFL, the drums are taken out and the empty packagings are returned to the NFT.

These empty packagings are temporarily stored in the NFT owned Packaging Control Center, where they are cleaned, checked and repaired and delivered to the power plants whenever necessary (Fig.7)

Oerhoad crnrwj

Outdoor storage area Number of packagings

dtspatchod per day: 200 MR. LLW Disposal

Center Control Bdg

~ Reception of packagings (40 per day)

Outdoor storage area

Fig.7 Packaging Control Center 3. Development of the packaging

The mass transport of the LLW was to be made in Japan for the first time and especially sea transport was not frequently done in the world when it was planned.

Therefore in developing the packagings, thorough deliberation and testings were repeated in view of compliance assurance and ease of handling.

It took about 6 years to complete the R&D and the fabrication of 3,000 units of the IP-2 packagings. The development was proceeded as follows:

Deliberation on the basic specification

At the first stage of the deliberation it was not clear whether the drum itself or the container should be considered the packaging and it was argued whether a simple open rack or an enclosed container should be used.

The enclosed container was finally selected on the judgement that it would be desirable to enclose the drums in a container from, both containment performance and public acceptance point of view.

It was considered that the container should not be of standard type but should be the specific one which would be best suited to the transport system.

Regarding the capacity of the container venous number of drums were comparatively examined; 4 drums (2 drums x 2 rows), 8 drums (2 drums x 4 rows), 16 drums (4 drums x 4 rows), 18 drums (3 drums x 3 rows x 2 tiers), 24 drums (3 drums x 8 rows) and so on and 8-dnim container was selected in consideration of ease of handling at the warehouse and possibility of loading on the standard 11-ton truck (Fig.8).

Detail design

In 1991, Japanese transport regulations were amended to comply with the IAEA transport regulations of 1985 edition and the category of the Type IP—2 Packages was introduced. Therefore the detail design of the container was carried out to provide

Lid Lilting Hole

Fig.8 LLW Package

structural strength and leaktightness which satisfy the requirements of the Type IP-2 package. The compliance was confirmed by subjecting the models to stacking test and drop test (Fig.9)

Determination of number of packages to be manufactured

In determining the number of packages to be manufactured, a simulation analysis was performed in consideration of number of days required for packaging operations, inspections and receiving operations, and on the assumption of an LLW shipping plan that 25,000 LLW drums would be annually transported from the nuclear power plants.

Lilting Device

The number of packagings thus obtained with some spares resulted in the required number of 3,000.

Manufacture of the IP—2 packagings

The manufacture of 3,000 packagings was decided to be done by a local manufacure, Aomori Hoei Kogyo Company, with the objectives of promoting local industry. As the company had never fabricated containers, investment for new production lines was made and technical cooperation was provided by one of the major container manufactures, which resulted in monthly production of 200 containers.

4. Transport experience

The transport record of LLW in Japan is shown in Table 1. Some 20,000 LLW drums have been transported since the first shipment started in December 1992.

Table 1 Transport Record of LLW In Japan (as of 1.12.1993)

O-4

Fig.9 Testing of LLW Package * Japan Atomic Power Company

o_oo There has so far been no transport accident and all the IP-2 packagings stay quite sound and are repeatedly used.

Radioactivity of the package contents sometimes exceeded A2 but there has been no problem in view of specific activity limit of Az x 10~*/g.

5.Condusion

The transport of LLW has been successfully performed in Japan by means of containers which meet the requirements of the IP-2 packagings and the concept of the IP package is thought to be quite appropriate for mass transport of LLW.

TRANSPORT OF RADIOACTIVE WASTE