NRC Generic Letter 92-09, Limited Participation by NRC in the IAEA International Nuclear Event Scale

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December 31, 1992

TO: ALL HOLDERS OF OPERATING LICENSES OR CONSTRUCTION PERMITS FOR NUCLEAR POWER REACTORS

SUBJECT: LIMITED PARTICIPATION BY NRC IN THE IAEA INTERNATIONAL NUCLEAR EVENT SCALE (GENERIC LETTER 92-09)

PURPOSE

The U. S. Nuclear Regulatory Commission (NRC) is issuing this generic letter to inform licensees of its recent decision to participate in the International Nuclear Event Scale (INES) of the International Atomic Energy Agency (IAEA).

The NRC decided to participate in this program in a limited way to foster international cooperation. The NRC expects that the limited use of INES will have a negligible effect on its licensees or on State and local governments.

The participation of the NRC is not intended to affect emergency classifi-

cations, event reporting to the NRC, or communications with the public. Nevertheless, usage of the INES could lead to confusion with the existing four-level emergency response scale used in the United States. This generic letter discusses the measures and conditions of the limited participation to prevent any adverse effect. It supersedes the previous position of the NRC not to participate in the INES program (letter from E. L. Jordan, Director, NRC Office for Analysis and Evaluation of Operational Data, to NRC licensees, dated August 22, 1990).

DESCRIPTION OF THE SCALE

The INES is a tool intended to promptly and consistently communicate to the public the safety significance of reported events at nuclear installations by providing a common terminology among the nuclear community, the media, and the public for describing the events. The INES was designed by an international group of experts convened jointly by the IAEA and the Nuclear Energy Agency (NEA) of the Organization for Economic Cooperation and Development. The group was guided in its work by the findings of a series of international meetings held to discuss general principles underlying such a scale. The INES also reflects the experience gained from the use of similar scales in France and Japan as well as from consideration of possible scales in several other countries.

Events are classified in the INES at several levels. Events of greater safety significance (levels 4-7) are termed "accidents," events of lesser safety significance (levels 1-3) are termed "incidents," and events of no safety significance (level 0 or below scale) are termed "out-of-scale deviations."Generic Letter 92-09December 31, 1992

DISCUSSION OF LIMITED NRC PARTICIPATION

The IAEA adopted certain precautions on the use of the INES. They are given in a leaflet describing the structure and use of the INES (Attachment 1). NRC licensees or state or local governments do not need detailed instructions for event rating because the NRC will complete and submit event rating forms (Attachment 2) to the IAEA.

The NRC will limit its participation by classifying and submitting forms only for events at nuclear power plants that are classified as an alert or higher on the emergency response scale used in the United States. Not every alert will necessarily have an INES classification, as some may be rated below the INES scale.

When the NRC receives a report of an event, it will delay the assignment of an INES level number for about a week after termination of the event, to consider subsequent developments in assigning the number. This time delay will help prevent any confusion with the U.S. emergency classification. The NRC will notify State and local governments and the affected licensee of its INES classification. The NRC will not request of any of these parties a review or concurrence with the NRC classification. The NRC does not plan to issue a press release associated with the classification, but will provide copies of the transmitted event rating form to the concerned licensee and to the NRC Public Document Room.

The NRC remains bound to the early notification and assistance conventions formally approved by the IAEA General Conference in September 1986. These conventions provide for an international exchange of information, data, and assistance during a nuclear accident or serious radiological emergency.

BACKFIT DISCUSSION

This generic letter conveys information about the participation of the NRC, an agency of the United States, in the international program of the IAEA for classification of nuclear events. By this generic letter, the NRC staff does not request any licensee or applicant to submit information to the NRC, does not recommend any new regulatory action, and does not modify any existing regulatory position of the NRC staff. Consequently, this generic letter does not represent a backfit.

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Generic Letter 92-09December 31, 1992

This generic letter requires no specific action or written response. If you have any questions about this information, please contact the technical contact listed below, who is the NRC INES Coordinator.

ORIGINAL SIGNED BY

James G. Partlow Associate Director for Projects Office of Nuclear Reactor Regulation

TECHNICAL

CONTACT

Denwood F. Ross, Jr., Deputy Director Office for Analysis and Evaluation of Operational Data U. S. Nuclear Regulatory Commission Mail Stop 3701 MNBB Washington, D.C. 20555 Telephone (301) 492-7361

Attachments:

1. INES Description

2. INES Event Rating Form

3. List of Recently Issued Generic Letters