On March 11, 2011, the strongest earthquake in almost a century struck off the northeast coast of Japan. More than 21,000 people are dead or missing in the devastation from this 9.0 earthquake and the ensuing tsunami. Numerous nuclear plants in Japan were shut down automatically. However, the closest nuclear plant impacted by the tsunami, Fukushima Dai-ichi, was crippled, subsequently leading to releases of radioactive steam and waste water. The events at reactors 1, 2, and 3 have been rated at Level 7 on the UNAEA scale, which “indicates major release of radioactive material with widespread health and environmental effects requiring implementation of planned and extended countermeasures.” In support to the Japanese, Operation Tomodachi was initiated by the United States Armed Forces to assist and support Japan in disaster relief. This paper focuses on radioactive waterborne hazard modeling efforts by the DTRA Technical Reachback team. The DTRA Technical Reachback capability provides 24/7 operational support and planning for consequence assessment collateral effects as well as force protection. Reachback is a team of WMD subject matter experts with the ability to leverage expertise across DoD. It is an example of the Tech/OPS interface that brings the best S&T to bear on urgent CWMD matters.

This paper describes a successful two week multi-disciplined multi-organizational effort to adapt an existing waterborne transport model, SHARC (System for the Hazard Assessment of Released Chemicals) developed by Applied Science Associates for use during Operation Tomodachi. This effort represents the use of state-of-the-art S&T tools and subject matter expertise to provide urgent decision-support information to the United States Forces Japan (USFJ) Commander. Ocean environmental data were provided by Navy Oceanography Office (NAVOCEANO), Naval Oceanographer Anti-Submarine Warfare (ASW) Center (NOAC), at Stennis, MS. Off-shore sensor data from TEPCO and Ministry of Education, Culture, Sports, Science & Technology (MEXT) were used to benchmark the hazard predictions for I-131, Cs-134 and Cs-137. Department of Energy Federal Radiological Monitoring and Assessment Center (FRMAC) aerial monitoring data were used to validate general tidal features of the transport of radioisotopes. Waterborne hazard estimates addressed the 7th Fleet's operating environment concerns and potential for contamination of shipboard potable water. Various levels of concern, based on EPA standards for drinking water, were developed in collaboration with USFJ.

The waterborne transport capability was based on Dai-ichi facility run-off water contamination. Ground deposition (especially from the NW corridor) may have contributed to significant hazards from water run-off from the larger Japanese watershed/infrastructure. A proof-of-concept integration of SHARC and Incident Commander Water (IC Water) was demonstrated in an effort to account for sources of radioactivity removed from Dai-ichi. IC Water models airborne and direct deposition onto estuaries, ground and water treatment networks. IC Water output is used as a source term input to the SHARC ocean transport; however, these integrated models were not used for operations because watershed/river sensor data either did not exist or were not available for benchmarking these models