NAPSNet Special Report
May 14, 2013
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Handbook to Support Assessment of Radiological Risk Arising From Management of Spent Nuclear Fuel

by Gordon R. Thompson

May 14, 2013

This handbook was produced for of the Institute’s Resilience and Security of Spent Fuel in East Asia project with the support of the John T. and Catherine D. MacArthur Foundation.

I. Introduction

Commercial nuclear power plants around the world harness nuclear fission to produce electricity. At each plant, a fission reactor receives fresh nuclear fuel and discharges spent nuclear fuel (SNF). Although the SNF is “spent”, it contains a large amount of radioactive material. Some of that material could be released to the environment by an accident or an attack, causing harm to humans by exposing them to ionizing radiation. The potential for such harm is the “radiological risk” associated with SNF. Independent assessment of this risk could help societies to manage the risk. This report is designed as a handbook that could be used to support such independent assessment. The report has two main parts. The first part provides introductory material, and the second part sets forth a seven-step approach to assessing SNF radiological risk.

Gordon D. Thompson, Phil., is currently the executive director of Institute for Resource and Security Studies in Cambridge, MA. In addition, he serves as Research Professor, George Perkins Marsh Institute, Clark University, Worcester, Massachussetts.

The views expressed in this report do not necessarily reflect the official policy or position of the Nautilus Institute. Readers should note that Nautilus seeks a diversity of views and opinions on significant topics in order to identify common ground.

II. Handbook by Gordon Thompson

Handbook to Support Assessment of Radiological Risk Arising From Management of Spent Nuclear Fuel


This report is designed as a handbook that could be used to support independent assessment of a particular risk associated with the world’s nuclear-power industry. The industry operates about 440 nuclear power plants (NPPs) that harness nuclear fission to provide about 14 percent of world electricity production.[1] 

Harnessing nuclear fission creates various types of risk. This handbook focuses on a particular type of risk with two major features. First, the risk is associated with spent nuclear fuel (SNF) discharged from the fission reactors at NPPs. Although the fuel is “spent”, it contains some fissionable material – uranium and plutonium – and a large amount of radioactive material. Second, the risk is “radiological”. Section I.2, below, defines radiological risk in the context of this handbook. In brief, this term refers to the potential for harm to humans as a result of their exposure to ionizing radiation due to an unplanned release of radioactive material.

The radiological risk posed by SNF has existed since fission reactors first operated. Over the intervening decades, the risk has increased due to growth in SNF inventories, changed properties of nuclear fuel, and design choices regarding modes of SNF storage. These factors are discussed in Section I.4, below.

Public awareness of SNF radiological risk was low before the 2011 accident at the Fukushima #1 nuclear site in Japan. Awareness grew during that accident, as citizens learned that SNF was stored in pools adjacent to the affected reactors, and that there was a potential for a large release of radioactive material from this SNF to the atmosphere.

This handbook addresses a range of technical issues. Each issue is complex, and is associated with a substantial technical literature and body of practical experience. Here, much of the complexity is avoided. A comparatively simple approach to assessing SNF radiological risk is set forth, involving various assumptions and simplifications. With this approach, analysts can assess the risk using a sequence of hand calculations and judgments that is easy to follow. The findings could be used for a variety of public policy purposes. However, the findings should not be used in situations where a more detailed analysis is required. This matter is discussed further in Section I.5, below, which addresses the purpose and scope of the handbook.

The present level of SNF radiological risk is not inevitable. Instead, it reflects choices made by the nuclear industry and accepted by regulatory organizations. Options are available whereby the risk could be substantially reduced. Some options would affect the operation of NPPs, while others would not. In the analytic approach set forth in thishandbook, risk-reduction options are considered as part of an assessment of the collateral implications of SNF radiological risk. Various collateral implications are important.

Users of this handbook are advised to inform themselves about SNF radiological risk from as many sources as possible. The handbook should not be used uncritically, but as a framework to guide a user’s exercise of informed judgment. Good judgment can be cultivated by reading technical literature, visiting nuclear facilities, and pursuing dialogue with colleagues. In addition, hand calculations using simple models can build understanding of the basic physics and chemistry, and appreciation of the magnitudes of relevant indicators. Computer-based models are available to address many of the technical issues discussed here, but a computer model should only be employed when the user is thoroughly familiar with its underlying principles.

The structure of this handbook is explained in Section I.6, below. In brief, there are two main parts of the handbook. Section I provides introductory material. Section II describes a seven-step approach to assessing SNF radiological risk.

This is only a portion of the full handbook. Click here to read the handbook in it's entirety

III. References

[1] Nuclear fission’s share of world electricity production was about 14 percent in 2010, down from a peak of about 17 percent in the early 1990s. (See: World Nuclear Association website, http://www.worldnuclear. org/info/inf01.html, accessed on 16 February 2012.)

IV. Nautilus Invites Your Responses

The Nautilus Peace and Security Network invites your responses to this report. Please send your response to: Comments will only be posted if they include the author’s name and affiliation.

V. Recommended Citation

Gordon R. Thompson, "Handbook to Support Assessment of Radiological Risk Arising From Management of Spent Nuclear Fuel", NAPSNet Special Reports, May 14, 2013,

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