1. Statistical Methods for Reliability Engineering α-Particle Inter-arrival Time & System Design Requirements -Christopher M Harrington 31 March 2008 Sustainable Radioactive Fuels This document contains private administrative and/or financial information of Sikorsky Aircraft Corporation, which is submitted in confidence. No disclosures or use of this information is permissible without the prior written consent of Sikorsky Aircraft Corporation, except as specifically authorized by law. Disclosure otherwise may result in criminal penalties pursuant to 18 USC 1905.

2. Sustainable Radioactive Fuels: Introduction Reliability of radioactive decay of persistent α-particles and the distribution thereof is an important factor in understanding the control of such sustainable fuel sources. Continued research in pulse-rockets require a significant amount of fuel as well as a highly reliable system to isolate any radioactive material. Design of such vehicles requires a strong knowledge of the particle emissions and required materials to isolate such decay.

3. Review of existing data on the decay of Americium-243 & -241Review of existing data on the decay of Americium-243 & -241 Americium-241 is a byproduct of the decay of Americium-243 by α-Particle decayAmericium-241 is a byproduct of the decay of Americium-243 by α-Particle decay Data gathering from stoichiometry and known Am-241 papersData gathering from stoichiometry and known Am-241 papers Formulation of trend, distribution & reliability functionsFormulation of trend, distribution & reliability functions Increase confidence levels by changing data sample sizeIncrease confidence levels by changing data sample size Determine path-forward for material matrix layeringDetermine path-forward for material matrix layering Sustainable Radioactive Fuels: Methodology

4. Sustainable Radioactive Fuels: Discussion MTTA: is defined as Mean Time to Particle Arrival MTTA:=G/λ where λ is the arrival rate of individual α-particles from data MTTA follows an exponential distribution with arrival rates normally distributed Use of MAPLE® to determine decay function and particle inter-arrival rates. Simulated layers of protection from particle decay emissions Correlated data with increased reliability per increased samples and known decay rates

5. Sustainable Radioactive Fuels: Discussion Alpha radiation consists of helium-4 nuclei and is stopped by a sheet of paper. Beta radiation, consisting of electrons, is halted by an aluminum plate. Gamma radiation, consisting of energetic photons, is eventually absorbed as it penetrates a dense material. 241-Am has Decay Energy of 5.638 MeV and requires 0.01 cm of Pb for containment of this energy p=0.505 p=0.858 Increased distribution confidence on a factor increase of sample

6. Sustainable Radioactive Fuels: Conclusions Increased data sources increase reliability of measurements: n=20: Std Error 52 n=200: Std Error 13 n=2000: Std Error 3.8 For highest reliability need n=10220. This reduces the std error in the distribution to 1.7; still need higher for public to be comfortable with isotopes. Scale (wrt IQR) increases in accuracy from 3.1 to 2.2 with a correlation factor of 0.966

7. Pb Sustainable Radioactive Fuels: Path Forward Increased Decay Analysis: -Monte Carlo & Process Simulations -Link to current Decay half-lift data Correlate absorption coefficients and angles with radioactive isotope for Aluminum and Lead: -Aluminum not required for α & λ particles -Lead requires 0.01 [cm] for 150% reliability