GENERAL38529 - Laserfiche WebLink

Home Browse Search

these wind patterns. Accordingly, the environmental samPliny location proximate to tl~e west property boundary is located such that it is virtually unaffected by the valley wind patterns and is expected to yield airborne particulate concentrations uninfluenced by the licensed facilities. IV. Pathways A. External Dose - Direct Gamma Radiation The mineralc~yy surrou m.li n~~ tl~c ltcruse:J f~~~rlitirs make., tlir determination of a "i~et" dose for ga«uua tedtation trom th~_ licensed facilities difficult. The mineralogy of tl~e ot,t,osiny valley slopes at the Sttr is quite different. Specificall:~, the valley side east-northeast of the site is much young e!: than the valley side nest-northwest of the site. The age .it the east-northeast side is on the order of millions of years, while the west-northwest side is about 4 to 4.5 billion y.-ars old. Needless to say, this leads to a vastly different mineralogy. The east-northeast side is comprised mostly o1: sandstones, mudstones, clay and conglomerates, while the west-northwest side is made up of metamorphosed gneisses <~~td schists. Geology types such as sandstones, mudstones, and clays are historically associated with higher "background" gamma counts than the metamorphosed types. This difference in mineralogy substantially limits the usc~ of a thermoluminescent dosimeter (TLD) for background subtraction. To address this problem, Cotter proposed the placement of ten TLDs on the east-northeast valley side for a period of one year. This proposal was approved by Radiation Control and monitoring began on April 1, 1988. The one year monitoring period was completed in 1989 and the average annual background gamma radiation exposure for the ten locations studied was 184 mRem. A gamma dose is not attributed to the licensed facilities and is not included to the ottsite dose conunitment because the background study data of 184 mRem/year exceads the pro7ecteri 173.6 mRem/year from monitoring data cc11CC•ted from January through June 1993 (81.8 mRem) and the previous six months for the environmental sampling location which approximates the nearest feasible resident.