MESA RADIOLOGICAL ASSESSMENT, SURVEY PLAN AND DATA BOOK 1 OF 1 MEMORANDUM FOR FILE April 10, 2014 SUBJECT: Assessment of Radiological Events at the Mesa EXECUTIVE SUMMARY During the 1980s, radioactive material that had been inappropriately transferred from the site was discovered at the Mesa. That material was primarily contamination on tools and equipment that had been inadvertently released from thesite as a result of a material release program that lacked the necessary rigor and was not well enough implemented to intercept all contaminated items among the thousands of items moved to the Mesa. Since the Part 50 license did not include the Mesa, the receipt. storage, or use of radioactive material was not permitted there. ConSequently, the discovery of anything with radioactive contamination required immediate and complete removal; contaminated items were immediately secured, transferred back to the site. and the area was veri?ed to be free of residual contamination. This assessment was accomplished through a review of historical records and through interviews with current and former San Onofre employees who have knowledge of the Mesa. The intent of this assessment is to identify those locations at the Mesa that were affected by the inappropriate presence of radioactive materials. In addition. this assessment supports a foundation that will assist in determining, for each specific event and location, whether or not additional radiological surveys are appropriate to confirm the complete cleanUp of radioactive materials before termination of appropriate land leases and eventual turnover to the Department of the Navy. INTRODUCTION Principle Nuclear Regulatory Commission (NRC) regulations that govern the planning for and decommissioning of a commercial nuclear power plant are 10 CFR 201401-1406 ?Radiological Criteria for License Termination." 10 CFR 50.82 "Termination of License? and 10. CFR.5D.75 ?Reporting and Recordkeeping for Decommissioning Planning." implementation of the radialogical assessment requirements are described in NUREG- 1575. Rev 1 ?Multi? Agency Radiation Survey and Site Investigation Manual Chapter 3 provides guidance for performing a Historical Site Assessment (HSA.) The Mesa and its facilities were never part of the Part 50 license for the San Onofre Nuclear Generating Station (SONGS) and therefore not intended for receipt. storage. or use of any radioactively contaminated tools, materials, or equipment. As such, the discovery of anything with radioactive contamination required immediate and complete removable with an acceptance criterion of "no detectable." The only acceptable result for each event was