RECYCLED SCRAP METAL AND SOILS/DEBRIS WITH LOW RADIOACTIVE CONTENTS

A.W. CARRIKER

US Department of Transportation,

Washington, D.C., United States of America Abstract

Two types of large volume bulk, shipments of materials with low radioactivity have characteristics that complicate compliance with normal transportation regulations. Recycle scrap metal sometimes contains radioactive material that was not known or identified by the shipper prior to it being offered for

transportation to a scrap recycle processor. If the radioactive material is not detected before the scrap is processed,

radiological and economic problems may occur. If detected before processing, the scrap metal often will be returned to the

shipper, uranium mill-tailings and contaminated soils and debris have created public health problems that required moving large volumes of bulk material to isolated safe locations. Similarly, old radium processing sites have created contamination problems needing remediation. The U.S. Department of Transportation has issued exemptions to shippers and carriers for returning rejected scrap metal to original shippers. Other exemptions simplify transportation of mill-tailings and debris from sites being remediated. These exemptions provide relief from detailed radioassay of the radioactive content in each conveyance as well as relief from the normal requirements for packaging, shipping documents, marking, labeling, and placarding which would be required for some of the shipments if the exemptions were not issued.

1. Introduction

Sometimes bulk recycled scrap metal containing undetected radioactive material has been processed at steel mills or other facilities causing serious radiological problems or contamination of the facility which may require shut down of the facility and clean-up costing millions of dollars. If the radiation from the shipment of scrap metal is detected prior to processing, the materials are usually returned to the shipper. Since the original shipper did not know that radioactive material was present, the identity and activity of the radionuclides in the returned shipment is not readily available. These return

Disclaimer: The presentations of statements and information in this paper are strictly those of A. Wendell Carriker and are not to be considered

representations of facts or policy by the U . S . Department of Transportation.

shipments containing unidentified radioactive material are difficult to classify and offer for transportation within existing transportation regulations.

Processing uranium for nuclear programs has resulted in massive volumes of uranium mill-tailings. Processing of radium many years ago resulted in residues that were disposed of with little concern for low level radiation exposure. Unacceptable radiation hazards to the general public exist where uranium, thorium, and radium waste have intentionally and unintentionally been

deposited. To mitigate this public health problem, large volumes of tailings, soil, and debris need to be transported to

radiologically safe locations. Soil and debris shipped from sites being decommissioned and decontaminated often contain naturally occurring radionuclides with low but uncertain specific activity. Sometimes these materials are below ehe 70 Bq/g (2 nCi/g) definition of radioactive material, and in other cases the activity greatly exceeds the definition. Without knowledge of the activity in the material in each vehicle or bulk container, it is difficult to classify the materials and offer the shipments in accordance with the regulations.

The U.S. Department of Transportation (DOT) Hazardous Materials Regulations have statutory provisions that allow the issuing of exemptions that grant relief from regulatory requirements.

Information submitted in applications for exemptions must demonstrate that the level of safety for shipments under the exemption will be equivalent to the level of safety if shipments net all normal transportation requirements. Exemptions issued to Federal and State organizations allowed shippers and carriers to make shipments in a controlled and operationally effective manner. These exemptions allow the shipments to be made without analysis of the material in each vehicle or bulk container.

Further, they provide relief from the usual requirements for packaging, shipping documentation, marking, labeling, and placarding. The exemptions are similar to Special Arrangements under Safety Series No. 6 or the transportation systems approvals being considered for the regulations in 1996.

2. Recycled Scrap Metal Problem

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Radioactive material in recycled scrap metal is occurring too often in steel production. However, it has also been found during the recycling cf aluminum, copper, lead, and gold. The problem is international and is evidenced by radioactivity being detected in scrap and other metals entering the United States from about ten other countries. The radioactivity is usually detected in recycled scrap prior to the production of new products, but in other cases it has been found in products and waste/byproducts associated with the production.[1]

The radiation hazards associated with the unknown radioactivity have ranged from potentially acute effects to radiation levels

representing a small fraction of background radiatior. The radioactive material creating these conditions has ranged from sealed sources with activities in excess of a TBq to materials such as refractory bricks that are not normally considered radioactive, but because of thorium content emit very low level ganuna radiation. One well known example of a large source being processed during recycling was the '"'Co from a teletherapy unit in Juarez, Mexico in 1983. The undetected discrete sources that have caused most of the shut downs these past few years have been

)37Cs sources, probably from radiation transmission gauging devices, with activities in the range of 20 GBq (0.5 Ci). The products that most commonly caused the radiation detection systens to alarm contain radium—examples are sections of oil-well pipe with scale and other metal from systems that process materials with trace amounts of naturally occurring radioactive materials.

To avoid radiological problems and costly shut downs many facilities have installed high sensitivity radiation monitoring systems, often computer controlled, to look for the presence of radiation from vehicles bringing feed stock into the facility and for monitoring products leaving the facility. The sensitivity of these systems hopefully will detect the presence of a shielded source that is further shielded by large amounts of other

material in the load. The computer controlled monitoring systems can detect radiation levels that are a small fraction above normal background radiation. When the radiation level from a conveyance exceeds the alarm threshold such as 0.02 uSv/h

(2 urem/h) above a normal background of typically 0.15 uSv/h (15 urem/h), other radiation monitoring instruments are used to verify and/or identify the presence or absence of radiation.

Obviously, setting the alarm thresholds extremely low can cause problems with excessive numbers of false alarms. When the radiation monitoring systems alarm, the system cannot distinguish whether the radiation comes from a large well shielded source in the center of a heavy load of scrap or from a slightly

concaminated piece of metal at the external wall of the

conveyance. When the presence of radiation has been verified by the additional measurements, the shipments are typically rejected as a condition of purchase between the scrap recycler and the scrap supplier.

The suppliers of scrap metal are seldom aware in advance of the occurrences when radioactive material is present when the bulk shipments of scrap are offered for transportation. The shipments with the detected radioactive material are often returned to the original shipper because the processing facility does not have the resources or chooses not to accept the responsibility for handling the radioactive scrap. In a few cases, the processors have established areas where the problem loads are carefully unloaded and sorted to find the radioactive materials under the scrutiny of a technical specialist with radiation monitoring equipment. Such specialists are usually approved by the radiological health authority of the State where the load is being processed. In these cases, the special handling and

radioactive material disposal must be handled between the

processor and original shipper. Under an exemption issued by the DOT [2], evaluation of the radiological conditions and the

coordination of activities between the processor and original shipper is delegated to the State radiological health official in the State where the radioactive material is detected.

Under normal transportation regulations a regulatory dilemma is present when the recycling facility returns a load to the original shipper. First, radioactive material is clearly being transported because the radiation monitoring equipment detected radioactive material, but the identity and amount of radioactive material is not known. Second, regulations prohibit transporting radioactive material unless specific information is known and described on documentation accompanying the shipment, and when necessary markings, labeling, placarding, etc. are provided.

The DOT exemption for these shipments relies heavily on the radiological health officials in each of the fifty States. These officials have the basic responsibility for the health and safety of the public and the environment in their State for all types of radioactive material and other sources of radiation. They are also usually the persons responsible for resolving radiological conditions during emergencies. The DOT exemption authorizes shippers to offer and carriers to transport these scrap metals without compliance with a number of regulatory provisions.

However, in the exemption DOT limits the external radiation levels outside the vehicle to no more than 0.5 mSv/h (50 mrem/h) and the radioactive material must not be readily dispersible.

The exemption further requires that the shipper and carrier comply with the conditions prescribed by the State radiation official on a shipment approval document that must accompany the exemption with the transport documents with the shipment. The transport documents must include the following description of the consignment:

"Scrap metal for recycle containing unidentified radioactive material causing low levels of radiation outside the

transport vehicle. Shipment is under Exemption DOT-E 10656 without a determination of materials meeting or not meeting the regulatory definition of radioactive material. The shipment is a minor radiological concern based on

considerations of the U.S. Department of Transportation and the State Official signing the attached Shipment Approval document".

The Shipment Approval form signed by the State official has the names and telephone numbers of the facilities and the responsible individuals that originally offered and received the shipment.

It describes the radiation levels that were detected outside the vehicle that is carrying the scrap. It identifies the name of the responsible individual at the destination where the material is to be moved under the exemption. It also identifies the name and telephone number of the responsible State official where the shipment is being sent. Any special conditions which the authorizing State official deems appropriate to assure safety of

the shipment also appears on the approval form along with the names, titles, and telephone numbers of the investigating and approving State officials.

During calendar year 1993 more than 40 shipments of scrap metal were returned to the sender under the exemption. During the same period several steel mills inadvertently processed radioactive scrap which forced shut downs. The numbers of shipments with detected radioactive material that were "reworked" during 1993 at the processing site without use of the exemption are not known.

It may be noted that more radiation monitoring systems are being installed at recycle scrap metal collection facilities as well as at the processing facilities.

3. Uranium Hill-Tailings Problem

The processing of uranium and thorium ores for more than half a century has resulted in millions of cubic meters of processed waste commonly referred to as tailings. In some locations these tailings are considered to present unacceptable hazards to the public and the environment. Host of these tailings are in well defined sites near the mills where the ore was processed years ago. However, some of the tailings had physical and chemical properties, not related to the radiological properties, that were attractive for uses in residential and public locations. Some of these uses included land-fill, soil conditioning, and

incorporation into masonry and construction products.

Some of the massive piles of tailings near populated areas were considered to present an unreasonable radiological risk due to radon in the air and radionuclides leaching into surface and ground water. The tailings that were used as land-fill and other materials around hones and residential areas created radon and other low-level radiation hazards that public health officials declared to be unacceptable. An Act of the United States Congress required remediation of these problems by moving the tailings and contaminated soils and debris to isolated

hydrologically acceptable locations.

The contractors who processed the ores and generated the tailings for the most part operated under government contracts. The U.S.

Department of Energy (DOE) was assigned the responsibility to remediate these uranium mill tailings problems. The first 16 sites that DOE chose to remediate involved both piles of tailings and locations where the tailings had created unacceptable

radiation hazards in residential areas. The DOE, and its present contractors, evaluated the conditions and prioritized the sites to be cleaned-up. The DOE recognized that some of these materials had specific activities that required they be

transported as regulated radioactive materials while others had specific activities less than the definition of radioactive material for purposes of transportation. DOE recognized it was difficult to know precisely what the specific activity and total activity would be from one load to another in a given area, and

it would be excessively costly to assay each and every load being moved to the acceptable locations.

in this program could be used for transporting other materials, they had to be thoroughly cleaned.

The DOE requested an exemption from DOT that would allow these shipments involving millions of cubic meters of materials to be transported in a safe and effective manner. Relief was requested from the requirements for packaging, shipping papers, marking, labeling, and placarding. In characterizing the hazards of the 16 sites to be remediated, the DOE performed corings and other assays which indicated that most of the materials to be remediated had gross specific activities ranging from 2 Bq/g

(40 pCi/g) to 300 Bq/g (8,000 pCi/g) , and occasionally materials would contain 2 kBq/g (50 nCi/g) . In remediating the sites, the clean-up criteria was based on 'Ra and was specified to be 0.2 Bq/g (5 pCi/g) for ground surface soils and a value slightly higher for soils deeper than 15 cm.

The exemption authorized DOE contractors to transport the materials by motor vehicle and rail without an analysis of the radioactive content of each load. [3] The site characterization surveys were considered to provide adequate information about the material being transported. The cognizant DOE remediation offices had sufficient information to analyze radiological risks if any mishaps occurred during transportation between a clean-up site and destination. Transportation documents accompanying the shipment did not need to contain the information normally

required for the transport of radioactive materials. Rather, the shipping documents had a generic description of the materials and actions to be taken in the event of an emergency. Further, the names and telephone numbers of Federal and State officials to be contacted for additional information or assistance in the event of an emergency were included with the documents. There were no specific criteria for the closed vehicles or rail cars that were to be used during transport; other than the materials should be protected so that radiologically significant amounts would not be lost during transport. The contractor carriers were obligated to report all spills or releases exceeding approximately 7 kg (15 Ibs) to DOE. DOE was not obligated to report spills to DOT unless the spills were much greater. According to the DOE plans, the same procedures were to be used for handling spills

regardless of the activity being above or below the transportation definition for radioactive material. The

conveyances were not required to be marked or placarded as would be normally required for bulk packagings. The usual radioactive material placard was considered to be an excessive warning for a material for which the hazards were considerably lower than most materials represented by the placard. Instead, a poster was required on opposite sides which indicated the content was low level radioactive material under the regulatory authority of DOE and DOT. It also stated that additional information could be obtained from an indicated telephone number or on documents in the cab of the conveyance. The exemption also required that the operating personnel have documented training concerning the hazards of the materials and the procedures to be followed in the event of emergencies. Before these bulk transport vehicles used

4. Radium In Soils and Debris Problem

During the early part of the twentieth century there were a number of locations in the United States where radium was extracted from ores. There are other locations where the radium was processed and used for a variety of purposes, some of which are considered very questionable in light of today's knowledge.

As decades have passed, the nature and location of many of these activities were lost, but the long half-life radionuclides that were in the buildings and the refuse from the processing remain.

Also, the character of the communities changed, and the old process sites have showed up in everything from fine residential areas to heavy industrial locations.

Following surveys by public health officials, many of these sites have been declared to be unsafe, and, by an Act of Congress, programs are underway to remediate these sites and transport the contaminated soils and debris to safe locations. The U.S.

Environmental Protection Agency (EPA) was assigned the

responsibility for the remediation of these radium contaminated sites. The standard for radium clean-up of sites was set at 0.2 Bq/g (5 pCi/g) for 224Ra at the surface of the ground and not more than 0.6 Bq/g (15 pCi/g) at depths greater than 15 cm. Since most of the corporations or individuals who were responsible for the contamination problems are no longer in business, the Federal Government has also assumed the financial expenses of the clean-up.

One of the most notable public health hazards existing in the radium contaminated areas was high radon concentrations in air at levels greatly exceeding the standards recommended by EPA. These conditions existed mostly in homes, but were also found in business and public buildings. In the course of investigating the radium and radon problems, EPA and other public health officials learned of the presence/location of contaminated areas from measurements taken with high sensitivity radiation detection instruments and from documented and word of mouth historical information.

In some cases, contaminated buildings and facilities were remediated and the transportation of the wastes to the disposal sites was done in compliance with DOT regulations. In other cases where there were a large number of sites and/or where large volumes of soils and debris needed to be transported, it was very ineffective to perform detailed assays and to transport the materials within the transportation regulations.

Typically to assay a small area of land to be cleaned-up, a grid pattern was established for the area. Radiation dose rates at ground surface or at a fixed distance above points on the grid

Typically to assay a small area of land to be cleaned-up, a grid pattern was established for the area. Radiation dose rates at ground surface or at a fixed distance above points on the grid