Interestingly, we had a small issue that became a large one due to the influence of the DOE.. We had a very small alara limit for neutrons around a bunch of UF6 cylinders. The dosimeters we used had Li-6 so they were very responsive to thermal neutrons but the calibration said that the spectrum was all fast. I suspected that the neutrons were being moderated by skyshine causing there to be an excess of thermals that make the dose look higher than before. I don't know if you will have that many neutrons as this was a few acres of cyclinders.. Just a thought. I wanted to do an experiment with some dosimeters just to see what we would find, but never got around to it.
Good luck, Rob Robert J. Gunter, MSc, CHP CHP Consultants/CHP Dosimetry www.chpconsultants.com www.chpdosimetry.com Toll Free: (888) 766-4833 Fax: (866) 491-9913 Cel: (865) 387-0028 [email protected] From: [email protected] [mailto:[email protected]] On Behalf Of BREHM, DAVID M Sent: Friday, November 04, 2011 7:30 AM To: [email protected] Subject: Powernet: RE: ISFSI/Dry Storage Neutron Spectrum I too am very interested in this. We did not do a neutron energy study last dry-cask campaign and, in retrospect, I really wish we had. We will be doing a study as part of the next campaign, but any data out there (we use the DMC-2000GN and OSLN) to get us closer to the mark will help a lot. One learning to share, the cask configuration changed from the first campaign (where a study was performed) to the second & most recent campaign. Among other things, the changed cask configuration improved the gamma shielding, but also had the effect of lowering the average neutron energy without really changing the neutron flux. The end result is that field neutron monitoring -- electronic dosimeter & portable instruments and record dosimeter -- were quite a bit different. David Brehm Fort Calhoun Nuclear Station Supervisor - Radiological Equipment & Dosimetry Office: 402.533.7582 Cellular: 402.214.0107 Pager: 402.561.3310 From: [email protected] [mailto:[email protected]] On Behalf Of Holmes, Stephen J Sent: Thursday, November 03, 2011 2:49 PM To: '[email protected]' Subject: Powernet: ISFSI/Dry Storage Neutron Spectrum Who out there has performed a neutron energy spectrum study specific to dry storage processes? We have good data on our containment spectrum, but have not yet done a specific study for dry storage. We are looking at ensuring our dosimetry/instruments are set up to respond properly to the dry storage neutron energies. The only plant I know of that has done this is Kewaunee. If anyone else has, I would appreciate any learnings you can share. If you haven't, and you have a good justification for not doing it, I am interested in that as well. Thanks, -Steve Stephen J Holmes Sr. Plant Health Physicist RE Ginna NPP Constellation Energy Nuclear Group [email protected] 585-771-3577; 585-545-1661 (cell) >>> 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 _____ This e-mail contains Omaha Public Power District's confidential and proprietary information and is for use only by the intended recipient. Unless explicitly stated otherwise, this e-mail is not a contract offer, amendment, or acceptance. If you are not the intended recipient you are notified that disclosing, copying, distributing or taking any action in reliance on the contents of this information is strictly prohibited.
