SONGS purchased the early version of the MicroRem, which could not be pulse calibrated. We calibrated all scales with sources, with the instrument inside a 4" lead shield.
Routine audits of instrument fleet "As Found" readings to determine/verify proper calibration cycle length showed excessive "out of calibration" results for the lowest scale of this instrument model. It appeared the problem was fluctuation due to a response time too short for the number of events counted. With the ever-changing analog response, the user has to simply guess the reading. We switched to newer circuit cards, and now pulse calibrate the lowest scale. NCRP 112, Page 44 states "electronic techniques may be used to extend the calibration to lower dose rates..." The process is further described in Appendix A-2. Roger Schanzenbach HP Technical Support San Onofre Nuclear Generating Station (949) 368-9580 From: "Pell, Bryan" <[email protected]> To: "'[email protected]'" <[email protected]> Date: 02/03/2011 07:39 AM Subject: Powernet: MicroRem Calibration Sent by: [email protected] Just a quick question. Ginna calibrates our microrem meters on the x1 scale electronically instead of calibrating on that scale against a source. We calibrate the other scales (x10, x100, x1000) against a source. This method is authorized in the tech manual but was challenged. What does your site do? Thanks, Bryan Bryan S. Pell R.E. Ginna Nuclear Power Plant Senior Plant Health Physicist (585) 771-3804 [email protected] P Please consider the environment before printing >>> This e-mail and any attachments are confidential, may contain legal, professional or other privileged information, and are intended solely for the addressee. If you are not the intended recipient, do not use the information in this e-mail in any way, delete this e-mail and notify the sender. CEG-IP1
