Summary of the Nuclear Risk Assessment Environmental...
Transcript of Summary of the Nuclear Risk Assessment Environmental...
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Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND NO. 2015-XXXXP
Summary of the Nuclear Risk Assessment for the Mars 2020 Mission
Environmental Impact Statement NETS 2015 Conference
February 23-26, 2015
Team Members
Daniel J. Clayton, John Bignell, Christopher A. Jones, Daniel P. Rohe, Gregg J. Flores, Timothy J. Bartel, Fred Gelbard, San Le, Charles W. Morrow, Donald L. Potter, Larry W. Young, Nathan E. Bixler and Ronald J. Lipinski
Acknowledgements Department of Energy Office of Space and Defense Power Systems (NE-75) National Aeronautics and Space Administration (NASA) Reviewers - Ryan Bechtel, Steven Giannino, Scott Hopkins and Yale Chang
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LAUNCH • MSL Class/Capability LV • Period: July/Aug 2020
CRUISE/APPROACH • 7.5 month cruise • Arrive Feb 2021
ENTRY, DESCENT & LANDING • MSL EDL system: guided entry and
powered descent/Sky Crane • 25x20km landing ellipse • Access to landing sites ±30° latitude,
≤0.5 km elevation • ~950 kg rover
SURFACE MISSION • Prime mission of one Mars year • 20 km traverse distance capability • Seeking signs of past life • Returnable cache of samples • Prepare for human exploration of Mars
Mars 2020: Mission Concept
http://mars.jpl.nasa.gov/mars2020/
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NEPA Requires EIS for the Mission
MISSION & LAUNCH
VEHICLE DATA (NASA)
ACCIDENT DESCRIPTIONS
(NASA)
SYSTEM DESIGN & TEST DATA
(DOE)
Nuclear Risk Assessment
(DOE)
Environmental Impact
Statement (NASA)
NASA Record of Decision
Sandia writes the Nuclear Risk Assessment for DOE for the Environmental Impact Statement
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Scope of EIS
The Mars 2020 EIS considers both radiological and non-radiological environmental impacts from the proposed action and the alternatives.
The analysis in the EIS includes:
Preparation for a Launch
Impacts from a Normal Launch
Possible Launch Accidents
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Mars 2020 EIS Mission Alternatives
Alternative 1 (Proposed Action): A rover powered by a Multi-Mission Radioisotope Thermoelectric Generator (MMRTG)
Full operability over one Mars year (687 Earth days) Complete access to desired landing site region (30˚ North to 30˚ South
latitudes around the planet) No restrictions on operations Highest science return of Alternatives
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Safety is built from the inside out and from the outside in. Analysis must quantify this for decision makers.
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Multi-Mission Radioisotope Thermoelectric Generator (MMRTG)
Launches Can Fail
Atlas Fallback
Delta 241 Jan 27, 1997
Titan 34D
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Launch Safety Analysis Approach Goal: Quantitative estimate of the risk for use by decision maker
Mean probability of release of PuO2 Amount of PuO2 released (“source term”) Health effects (dose, latent cancer fatalities over 50 years) Land contamination (e.g. square km of > 0.2 microCi/m2) All expressed as mean values, percentile values, and exceedance probability
graph (Complementary Cumulative Probability Distribution) Numerous phenomena need to be modeled
Blast and impact Fire and thermal Reentry Accident sequence options Atmospheric transport and consequences
Start with detailed understanding of the response of RPS to insults Perform detailed simulations and Monte Carlo sequence codes
used to develop the probabilistic risk analysis
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Launch Safety Code Suite
Databook Ch 5 Site
Ch 8 Accidents
Ch 3 Launch Vehicle Ch 6 Flight Safety
Ch 4 Spacecraft Ch 9 Explosive
Ch 9 Debris
Ch 3 Launch Vehicle Ch 9 Fire
Ch 7 Trajectory Ch 9 Reentry
Impact Sierra/SM Zapotec
CTH
Fire SFM
PEVACI SINDA
Reentry LAPS TAOS HANDI CMA
Data Tables
Accidents LASEP
Release Records
Consequence STORM
IAT HYSPLIT FDOSE
Meteorology Population Geography
Health Physics
Health Effects, Land Contamination
Risk Integration
CARS
Exceedance Probabilities &
Uncertainty
Legend Data Code
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Blast and Impact Modeling Blasts from launch destruct and
ground impact of propellant tanks or solid propellant fragments
Ground impact of MMRTG Impact of spacecraft and launch
vehicle debris on MMRTG and components
Impact of solid propellant fragments on MMRTG and components
SNL’s Sierra/SM used for analyses Hundreds of parallel processors,
days to weeks of run time for each configuration
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MMRTG 45° Impact at 75 m/s (terminal velocity is 60 m/s)
No fuel release
Solid Propellant Burn Modeling Solid propellant fire temperatures exceed iridium clad melt and PuO2
vaporization temperatures Modeling begins with extensive fire testing and data acquisition Uses Sandia’s Sierra/Fuego detailed fire model Export Fuego’s physics module into Fluent for scoping studies Feed results into Sandia’s PEVACI code for numerous accident simulations
Solid Propellant Burn Test Sierra/Fuego Simulation Fluent with physics module from Fuego
With sideward burn
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LAPS Reentry Code Description
Reentry Object Definition
Initial Reentry Conditions
Trajectory Definition (TAOS or user provided)
Nonablating Cold Wall Boundary Layer Heating
(BLUNTY, HANDI, or MAGIC)
Ablation & Heat Conduction (CMA)
MMRTG Breakup v-gamma Map (gamma is entry angle)
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LASEP Stochastically Simulates the Range of Potential Launch Accidents
Launch Accident Sequence Evaluation Program
• 100,000 lines of Fortran code
• Hundreds of subroutines
• Extensive QA
• Over a million accident scenarios run for FSAR
• LASEP Models:
– Rocket trajectory, accident time, liquid propellant explosion and fires, blast effects, fragment impact, component fallback, component ground impact, impact by debris, solid propellant fires, orbital reentry, and other phenomena
Land Impact Water Impact
Reentry
Blast
Fire
Impact by debris
Launch Accident Sequence Evaluation Program
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Release Locations and Amounts
LASEP models numerous potential scenarios, randomly choosing time of failure, explosion characteristics, etc.
Release location and amounts determined mechanistically
Probability distributions for release are determined Potential release locations from numerous LASEP launch simulations
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Consequence Modeling
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Sandia Transport Of Radionuclides Model (STORM) uses NOAA’s HYSPLIT code, leveraging NOAA’s extensive investment and readily accessing NOAA’s weather database
Calculate health effects from inhalation, resuspension, ingestion, cloudshine, and groundshine
Fireball Rise Height Particle Transport Land Usage
Mission Phases
Prelaunch – MMRTG installation to launch Early Launch – until no potential for land impact Late Launch – up to 100,000 ft Suborbital – end of first stage burn Orbital – until spacecraft separation Long Term – if spacecraft does not land on Mars and returns
to earth
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Source Term Results
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Overall accident probability – 2.5%
Conditional probability of release – 1.5%
Mean given a release 15.5 Ci
Consequences
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Overall mean given a release Maximum Individual Dose – 15.9 mrem Collective Dose – 126 person-rem Health Effects – 0.0759 Land Contamination – 1.94 km2
Cropland Intervention – 0.034 km2
Mission Risk
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Overall Mission Risk – 2.9E-05 (1/34,400) Main contribution to risk is from Early Launch accidents Uncertainty range, percentile confidence levels
5th – 1.2E-6 (1/833,000) 95th – 7.3E-4 (1/1,370)
Mars 2020 Record of Decision
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