Summary of the Nuclear Risk Assessment for the Mars 2020 Mission Environmental Impact Statement

Transcription

1 Photos placed in horizontal position with even amount of white space between photos and header Summary of the Nuclear Risk Assessment for the Mars 2020 Mission Environmental Impact Statement NETS 2015 Conference February 23-26, 2015 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-AC04-94AL SAND NO XXXXP

2 2 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

3 Mars 2020: Mission Concept 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 3 3

4 4 NEPA Requires EIS for the Mission MISSION & LAUNCH VEHICLE DATA (NASA) ACCIDENT DESCRIPTIONS (NASA) SYSTEM DESIGN & TEST DATA (DOE) Sandia writes the Nuclear Risk Assessment for DOE for the Environmental Impact Statement Nuclear Risk Assessment (DOE) Environmental Impact Statement (NASA) NASA Record of Decision

5 5 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

6 6 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

7 7 Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) Safety is built from the inside out and from the outside in. Analysis must quantify this for decision makers.

8 8 Launches Can Fail Delta 241 Jan 27, 1997 Atlas Fallback Titan 34D

9 9 Launch Safety Analysis Approach Goal: Quantitative estimate of the risk for use by decision maker Mean probability of release of PuO 2 Amount of PuO 2 released ( source term ) Health effects (dose, latent cancer fatalities over 50 years) Land contamination (e.g. square km of > 0.2 microci/m 2 ) 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

10 10 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 Impact Sierra/SM Zapotec CTH Fire SFM PEVACI SINDA Accidents LASEP Data Tables Legend Data Code Release Records Meteorology Population Geography Health Physics Consequence STORM IAT HYSPLIT FDOSE Health Effects, Land Contamination Ch 7 Trajectory Ch 9 Reentry Reentry LAPS TAOS HANDI CMA Risk Integration CARS Exceedance Probabilities & Uncertainty

11 11 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 MMRTG 45 Impact at 75 m/s (terminal velocity is 60 m/s) No fuel release

12 12 Solid Propellant Burn Modeling Solid propellant fire temperatures exceed iridium clad melt and PuO 2 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 With sideward burn Solid Propellant Burn Test Sierra/Fuego Simulation Fluent with physics module from Fuego

13 13 LAPS Reentry Code Description Reentry Object Definition MMRTG Breakup v-gamma Map (gamma is entry angle) Initial Reentry Conditions Trajectory Definition (TAOS or user provided) Nonablating Cold Wall Boundary Layer Heating (BLUNTY, HANDI, or MAGIC) Ablation & Heat Conduction (CMA)

14 14 LASEP Stochastically Simulates the Range of Potential Launch Accidents Launch Accident Sequence Evaluation Program Reentry Blast Impact by debris 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 Fire Land Impact Water Impact

15 15 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

16 16 Consequence Modeling 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

17 17 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

18 18 Source Term Results Overall accident probability 2.5% Conditional probability of release 1.5% Mean given a release 15.5 Ci

19 19 Consequences Overall mean given a release Maximum Individual Dose 15.9 mrem Collective Dose 126 person-rem Health Effects Land Contamination 1.94 km 2 Cropland Intervention km 2

20 20 Mission Risk Overall Mission Risk 2.9E-05 (1/34,400) Main contribution to risk is from Early Launch accidents Uncertainty range, percentile confidence levels 5 th 1.2E-6 (1/833,000) 95 th 7.3E-4 (1/1,370)

21 21 Mars 2020 Record of Decision