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Review of Hazards Associated with Molten Salt Reactor Fuel Processing Operations

Oak Ridge National Laboratory

Joanna McFarlaneMike Poore

August 13, 2019

A1

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A1 PowerPoint doesn’t have a tracking feature, but you can follow these steps to compare the new file to the original and review my suggestions:1. Open the original file on your computer and click the Review tab.2. Click the Compare button. A window will open, and you will be prompted to choose a file to merge with the original presentation.3. Navigate to and select the edited file, and then click Merge.4. A new file will open showing revisions in comment balloons. The revisions can be reviewed, accepted, or rejected. However, when the file is saved, it will not maintain the revision information.Author, 8/6/2019

22 Review of Hazards Associated with Molten Salt Reactor Fuel Processing Operations

Introduction

• Objectives

• Scope of work

• Report overview

33 Review of Hazards Associated with Molten Salt Reactor Fuel Processing Operations

Non–Light Water Reactor Policy and Technical Guidance Support, Letter of Technical Direction #6

• Tasks– ORNL shall collect information (and identify documents) on hazards: nuclear

criticality, fire, radiation, and reactive or toxic chemicals– The investigation shall consider hazards that are part of the primary process

operations, that are part of supporting operations (e.g., actinide recovery, waste management) or that are the result of design features or process equipment used for conducting primary or supporting operations

– The investigation shall consider . . . normal operations as well as those that are part of nonroutine operations (e.g., startup, maintenance)

44 Review of Hazards Associated with Molten Salt Reactor Fuel Processing Operations

Deliverables

• Kick-off meeting summary

• Letter report on major information sources

• Hazards report

• Knowledge management meeting with NRC staff

55 Review of Hazards Associated with Molten Salt Reactor Fuel Processing Operations

Review of Hazards Associated with Molten Salt Reactor Fuel Processing Operations

• ORNL/TM-2019/1195

• Available on www.osti.gov

66 Review of Hazards Associated with Molten Salt Reactor Fuel Processing Operations

Background

• Types of fuel salts

• Historic fuel salt preparation facilities– Aircraft Reactor Experiment– Molten Salt Reactor Experiment (MSRE)– Stripping of uranium from MSRE fuel and flush salts

77 Review of Hazards Associated with Molten Salt Reactor Fuel Processing Operations

Non-reactor site fuel salt processes and hazards

• Salt component synthesis

• Synthesis of MSR fuel salt

• Packaging and transportation of enriched UF6 and UF4

88 Review of Hazards Associated with Molten Salt Reactor Fuel Processing Operations

Reactor site fuel processes and hazards

• Liquid salt operations

• Fuel loading

• Fuel sampling

• Off-gas system

• Insoluble fission product filtering

• Soluble fission product separation

• Waste form preparation

99 Review of Hazards Associated with Molten Salt Reactor Fuel Processing Operations

Fuel salt processing hazard tables

• Process identified

• Salt type and process objective

• Refers to relevant report sections for the process

• Important hazards to consider for the process

• Qualitative assessment of maturity of process (TRL)

• Qualitative assessment of degree of hazard to operators(1–5)—no information on likelihood of exposure to hazard

• Engineering strategies to mitigate exposure to hazard

1010 Review of Hazards Associated with Molten Salt Reactor Fuel Processing Operations

Excerpt:Table 3a. Off-site nuclear fuel preparation and handling (continued)

Table 3a. Off-site nuclear fuel preparation and handling (continued)

Physical or chemical process

Salt type andprocess objective

Relevant report sections

Key hazards

Qualitative assessment

Qualitative severity judgment

Mitigation strategiesTRL: 1 (low) to 9

(high)Rank: 1 (low) to 5

(high)

• Salt purification• Hydrofluorination

Removal of oxides/hydroxides from fluoride salts

3.1.1

• H2/HF• Be if present as the

BeF2 salt component• Heat (650°C)• Contamination if

actinides present

7 4

Standard contamination control

for unirradiated materials

• Salt purification• Chlorination

Removal of oxides/hydroxides from chloride salts

3.1.1

• CCl4, Cl2, COCl2, HCl• Heat• Contamination if

actinides present

7 5

Standard contamination control

for unirradiated materials

• Packaging and transportation

Actinides and nonfissile components

3.3

• Contamination if actinides present

• Air-sensitive• Be (if present as

BeF2)

9 3Double barrier

container

1111 Review of Hazards Associated with Molten Salt Reactor Fuel Processing Operations

Fluoride salt production loop (Sections 2.2, 3.1.1)

1212 Review of Hazards Associated with Molten Salt Reactor Fuel Processing Operations

Excerpt:Table 3c. On-site fuel processing hazards during power operations

Table 3c. On-site fuel processing hazards during power operations

Physical or chemical process

Salt type and process objective

Relevant report sections

Key hazardsQualitative assessment

Qualitative severity judgment

Mitigation strategiesTRL: 1 (low) to 9 (high) Rank: 1 (low) to 5 (high)

Online sampling offuel salt during operation

Fluorides, chlorides to give salt composition

2.2.3, 4.3

• Very high radiation• Very high contamination

(leakage of volatile FP, actinides in salt & entrained aerosols)

• Heat• Air sensitive• Be (if present as BeF2)

4 5

• Remote handling• Inert gas flush• Double barrier

containment

Online sampling of fuel salt when loading salt during operation

Fluorides, chlorides to give salt composition

2.2.3, 4.3

• Flow restrictions/ pressure due to plate-out/freezing

• Very high radiation • Very high contamination

(leakage of volatile FP, actinides in salt & entrained aerosols)

• Criticality• Heat• Air sensitive • Be (if present as BeF2)

2 2

• Remote handling• Rapid measurements

(pressure, temperature, salt density)

• Purge gas pressure relief• Secondary containment

1313 Review of Hazards Associated with Molten Salt Reactor Fuel Processing Operations

MSRE sampler enricher (Sections 2.2.3 and 4.3)

1414 Review of Hazards Associated with Molten Salt Reactor Fuel Processing Operations

Summary—Wide range of hazards

• Hazards depend on fuel salt, processing operation, fissile material concentration, radiation level, and other toxic or hazardous materials

• Tables are used to summarize hazards in report

• Differences from solid-fueled reactors:– Refueling and adjustment of fuel salt chemistry online– Fuel processing closely coupled with reactor operations– Off-gas important for fission product confinement during normal operations

1515 Review of Hazards Associated with Molten Salt Reactor Fuel Processing Operations

Limitations of assessment

• MSR designs for the reactors and support systems are not fully mature, so only an overview of hazards can be provided based on the likely salt processing steps

• Limited experience with MSRs

• Can extrapolate from larger non-nuclear halide salt use

• Cannot assess inadvertent criticality during initial fuel transfer