Palo Verde provides the following response:
1) Scenario 1: Would we count this as an unanticipated dose rate alarm? No provided the worker responded to the alarm as required; however, if you received an alarm of 12 mr/hr I would assume that you set the electronic dosimeter alarm at 10 mr/hr and I would expect that at these alarm levels you receive numerous rate alarms whenever a worker encounters moderate radiation fields. 2) Does your site have an acceptance band for variations in briefed dose rate alarms versus actual dose rates encountered? Yes. We do not have a hard number such as 20% but your example fairly well covers how we would determine whether this would be considered to be anticipated or unanticipated. Are dose rates vary and electronic dosimeters are not survey instruments so a reasonableness test needs to apply. In your example a survey instrument indicates 100 mR/hr but a dosimeters may alarm at 120 mR/hr or 130 mR/hr. what do your follow-up surveys show? Was the worker in the location briefed? Based on how the electronic dosimeters operate ascribing that level of precision to a device that provides an approximation of radiological conditions to that of a calibrated survey instrument might preclude you from utilizing two effective ALARA tools: rate and anticipated alarms From: [email protected] [mailto:[email protected]] On Behalf Of Johnson, Graham T Sent: Thursday, April 25, 2013 4:23 AM To: [email protected] Subject: Powernet: Unanticipated Dose Rate Alarm Metric (KPI) Duke Energy would appreciate answers to the following questions regarding counting dose rate alarms as anticipated or unanticipated in your site metrics. 3) Scenario: An employee is briefed to expect a dose a rates of between 75 -150 mR/hr in route to a work area. The RWP/Task dose rate alarm setpoint is 75 mR/hr and the employee is briefed to anticipate a dose rate alarm. The employee logs onto the wrong RWP Task and receives a dose rate alarm at 12 mR/hr because he is on the wrong task. The actual dose rates encountered were as briefed. Would you count this as an unanticipated dose rate alarm? 4) Does your site have an acceptance band for variations in briefed dose rate alarms versus actual dose rates encountered and if so, what is the band? For example, if a worker is briefed to receive an anticipated a dose rate alarm of 100 mR/hr, is there a range above 100 that would be acceptable and then a point at which alarm would be called unanticipated? (e.g., if the band was +/- 25%, then 120 mR/hr would be an anticipated alarm but 130 mR/hr would be called an unanticipated alarm.) Thanks, Graham Johnson, CHP Supervising Scientist General Office Radiation Protection Duke Energy --- NOTICE --- This message is for the designated recipient only and may contain confidential, privileged or proprietary information. If you have received it in error, please notify the sender immediately and delete the original and any copy or printout. Unintended recipients are prohibited from making any other use of this e-mail. Although we have taken reasonable precautions to ensure no viruses are present in this e-mail, we accept no liability for any loss or damage arising from the use of this e-mail or attachments, or for any delay or errors or omissions in the contents which result from e-mail transmission.
