Overview of Hanford Site Risk
Assessment to Support CleanupDecision Making
Mark Triplett
Senior Advisor
Risk and Decision Sciences
1st International Forum on the Decommissioning of the Fukushima Daiichi NPS
April 11, 2016
PNNL-SA-116283

Overview
Hanford History
Cleanup Mission
Comparison to Fukushima Decommissioning Challenges
Development of Hanford’s Risk-Informed Cleanup Strategy
Risk Management Strategies
Applicability to Fukushima Decommissioning –DOE/PNNL/NDF Collaboration

Plutonium Production Mission
1943 – 1989; Current Legacy
106,000 tons ofuranium processed

2,300 tonsof spent
nuclear fuelremain974 tons ofplutonium
created~2,000 Capsules
5.6 x 1018 Bq

5Contaminated effluentsdischarged to theground: 1.7 x 1012 Liters

177 tanks
200 Million Liters
7.2 x 1018 Bq
PNNL-SA-115297> 500 contaminated facilities> 2,000 waste sites
32> 150 Km contaminated groundwater

Plutonium Production Mission –Key Facilities

PNNL-SA-115297

Hanford’s Cleanup Mission
Tri-Party Agreement signed by DOE, U.S. Environmental Protection Agency
and Washington state in 1989 – began the cleanup mission.
Surplus facility demolition
Reactor decommissioning – interim safe storageSpent fuel and nuclear material stabilization and storage
Near-surface soil and debris removal and disposal
Groundwater pump and treat, hydraulic control, and permeable barriers
Liquid effluent processing
Solid waste disposal operations
Tank waste storage and treatment

Development of a Risk-Informed Strategy
for the Hanford Site (1994-95)
Multiple types of risk that are not directly comparable
Near-term release hazards – high-consequence, low probability
Workplace hazards
Long-term hazards – threat to environment and public through transport ofcontaminants (especially contaminated groundwater transport to ColumbiaRiver)
Ecosystem hazards – threat to plant and animal life

Key elements of Hanford’s risk-informed strategy
Promptly reduce or eliminate near-term release hazards
Deactivate high-cost, high-risk legacy facilities that threaten the environment,
workers, and require active, expensive surveillance and maintenance
Remove waste sources close to the Columbia River
Contain and remediate groundwater contamination that threatens theenvironment and publicShrink the footprint of active remediation and waste management activities toa small, central portion of the SiteKey Challenges and Strategies for
Success
Dedicated Disposal Facility Enables Hanford Cleanup and Visible
Progress
Future Site Uses Work Group(1992): “Use the CentralPlateau Wisely for Waste
Management” – Broadpublic consensus recognized
the necessity for a dedicatedwaste disposal facility.
ERDF (central disposalfacility) built in 1995 allowed
real, visible progress tooccur.
Today, ERDF holds morethan 9 million m3 ofcontaminated material.

8Hanford Near-Term Release Hazards(1995 to Today)
High-risk nuclear
fuel and materials
Tank safety issues
Surplus reactors
Processing facilities
requiring active
safety controls

9Hanford Near-Term Release Hazards(1995 to Today)
High-risk fuel andnuclear material
moved to safe
storage away from
Columbia River
Tank safety issues
resolved
Surplus reactors
placed in interim
safe storage(isolated fromenvironment)
Processing facilities
deactivated andplaced in passive
safe condition
10

Long-Term Hazards – Remediation
Strategy
Contaminated soil
removed fromareas adjacent toColumbia River
Active remedies inplace for primary
threats togroundwater andRiver
Liquids removed
from undergroundsingle-shell tanks

Active Remedies in Place for11

Risk-Informed Strategy
NDF-PNNL Collaboration
Inventory(Source Term)

Release
Mechanisms

TransportMechanisms• Fuel and fueldebris• Stored spentfuel (poolstorage)• Contaminatedwater• Secondarywaste (fromwater treatment)• Building debris• Environmental
waste (soil andtrees)• Initiating events• Engineering
containment
systems• Waste form
releasemechanisms• Subsurface• Airborne• Ocean

Risk &Exposure
Assessment• Workers• Affected
Environment• PublicRisk-Informed Strategy
Current Focus for NDF-PNNL Collaboration
Inventory(Source Term)

ReleaseMechanisms

Transport
Mechanisms• Fuel and fueldebris• Stored spent
fuel (poolstorage)• Contaminatedwater• Secondarywaste (fromwater treatment)• Building debris• Environmental
waste (soil andtrees)• Initiating events• Engineering
containment
systems• Waste form
releasemechanisms• Subsurface• Airborne• Ocean

Risk &Exposure
Assessment• Workers• Affected
Environment• Public• Understand existing risks associated with spent
fuel and fuel debris• Support evaluation of fuel debris removal
options• Evaluate changes in risk over time to inform
decommissioning strategy

Thank You!