RPT 243Instructional Resources
Module 5:Radioactive Equipment and Systems
Table of Contents:
Resources Key......
Module Readings and Homework......
Primary Scenario “Technician Received Radiation Exposure to His Hand During Replacement of Source and Intermediate Range Monitor Dry Tubes in the Reactor Vessel”
Transfer Scenario “Workers Receive Excessive Radiation Dose While Changing a Filter”
Transfer ScenarioOriginal Event Descriptions
Transfer Scenario “Workers Receive Excessive Radiation Dose While Changing a Filter”
ACAD References......
Resources Key
This refers to: / This reference:ACAD / National Academy for Nuclear Training, Uniform Curriculum Guide for Nuclear Power Plant Technician, Maintenance, and Nonlicensed Operations Personnel Associate Degree Programs, ACAD 08-006.
DOE-SG / Office of Environmental, Safety and Health: Radiological Control Technician Training Site Academic Training Study Guide Phase I, Project Number TRNG-0003
Available at: File is located under the Docs/General Curriculum/DOE materials folder.
G. / Gollnick, D. (2006). Basic Radiation Protection Technology, 5th Ed. Pacific Radiation Corporation, Altadena, CA.
Module Readings and Homework
Primary Scenario “Technician Received Radiation Exposure to His Hand During Replacement of Source and Intermediate Range Monitor Dry Tubes in the Reactor Vessel”
Core Concept: Techniques and precautions for minimizing contamination and exposure from equipment and toolsHomework
Readings / Calculation Items / Non-calculation Items
DOE-SG-Mod 1.11-15 to 1.11-16
G., Chap. 11, pp. 452 - 454 / DOE-SG-Mod Sample prob. 1.11-11 and 1.11-12
G., Chap.11, # S-2 / N\A
Core Concept: Safe work practices in rapidly changing radiological conditions
Homework
Readings / Calculation Items / Non-calculation Items
N\A / N\A / N\A
Core Concept: Special precautions to control or reduce exposures when working with high-dose rate sources of radiation
Homework
Readings / Calculation Items / Non-calculation Items
N\A / N\A / N\A
Core Concept: Radiological consequence(s) of exposures involving high-dose rate radioactive sources
Homework
Readings / Calculation Items / Non-calculation items
N\A / N\A / N\A
Transfer Scenario “Workers Receive Excessive Radiation Dose While Changing a Filter”
- Refer to readings and homework for primary scenario above.
- The complete text of the event for this scenario is in the section “Transfer Scenario Original Event Descriptions” below.
Transfer ScenarioOriginal Event Descriptions
Use the complete text of these events to assess students’ ability to analyze the event, and apply appropriate safety and response procedures.
Transfer Scenario “Workers Receive Excessive Radiation Dose While Changing a Filter”
On May 2, 1997, three workers received excessive radiation doses while changing a spent fuel pool recirculation filter. Two of the workers exceeded both the whole body and extremity annual dose limits. The recorded whole body radiation dose for the three workers was 9.2 rem, 7.3 rem, and 4.1 rem. The limit for whole body exposure, during a calendar year, is 5 rem. The 50 rem limit for extremity radiation dose was exceeded for two workers with an estimated maximum of 142.9 rem and 113.87 rem dose to the skin of the hands, respectively.
The predicted dose rate during the filter change was on the order of a few millirem (mrem) per hour. When the filter was removed, the radiation protection technician recorded a dose rate on the filter of approximately 220 mrem/hour. After working on the filter for 10 minutes, one of the two radwaste workers noticed his direct reading dosimeter was off scale high. The two radwaste workers and the radiation protection technician left the area. The radiation protection technician returned with a different radiation survey instrument. This instrument indicated a dose rate of 240 rem/hour. The incident was then reported to radiation protection management.
Significant aspects of this event include the following:
- Three workers received excessive whole body radiation dose. Two of these workers exceeded both the whole body and extremity annual dose limits.
- The typical station practice of performing radiological surveys with only a Geiger-Mueller tube radiation survey instrument did not conform to the radiation protection technician training program requirement to use two types of radiation instruments to perform surveys (Geiger-Mueller tube and ionization chamber). The intent of this requirement is to identify instances of Geiger-Mueller tube saturation caused by high radiation fields.
- As a productivity measure, spent fuel pool filter replacement frequency was changed in June 1994. The new replacement criterion was based on filter differential pressure and was made without adequate consideration of increased radioactivity buildup.
- Station logs indicate that the differential pressure across this filter had peaked and began to decline about one year ago. The differential pressure trend was not effectively evaluated and, as a result, the filter was found degraded. Therefore, the differential pressure replacement criterion might never have been reached.
- Industry and station operating experience was ineffectively used to predict the expected dose rate for this evolution. Industry experience from similar plants indicated expected dose levels of approximately 300 rem per hour or greater for this filter. However, the station was unaware of this information. Periodic radiation survey results for the spent fuel pool filter were not trended as part of the process to determine the need for filter change or to determine current dose levels. As a result, expected radiation dose levels were not well established before the filter change.
- The radiation survey instrument used during this event was placed in service at the station approximately three years ago. Training on the use of the survey instrument was conducted during radiation protection continuing training at that time. There has been no additional requalification training on the use of this type instrument. Follow-up interviews after the event determined that some operational functions of the instrument were not understood by radiation protection personnel.
ACAD References
Note: ACADs listed in the RPT 243 instructors’ guide introduction document may also apply.
ACAD3.1 Plant Systems and Components Knowledge: Systems
- Identify conditions that preclude safet work in the vicinity of system components
3.3.11 CONDUCT AND MONITORING OF RADIOLOGICAL WORK
- Discuss proper job coverage and radiological protection measures for high exposure jobs and potential high exposure jobs, such as:
–In-core detector maintenance
3.3.12 RADIOLOGICAL INCIDENT EVALUATION AND CONTROL
- Identify the radiological consequence that may result from various incidents, such as:
–Uncontrolled spread of contamination
–Leak or spill of contaminated liquid
–Injury to an individual while performing radiological work
–Fire in the radiologically restricted area
–Loss of a high-activity radiation source
–Degraded core
–Uncontrolled or unsecured high radiation areas
Module 5Radioactive Equipment and Systems
The Curators of the University of Missouri
Copyright © 2008
A Product of DOL Grant #HG-15355-06-60
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