Linda,
Stays times for initial cavity decontamination activities during refueling outages are limited to 30 to 45 minutes due to temperatures. 1) Prior to drain down, water temperature is controlled solely through shut down cooling. This outage we had higher than expected ambient temperatures and had to utilize a back up portion of our emergency core cooling system to reach the Tech Spec temp limit prior to drain down. 2) Post drain down only the shutdown cooling system is used to maintain water temperature. The emphasis is more on time to boil rather than worker stay times for heat stress. 3) We have been successful in maintaining Containment Ventilation in service for the first few days of the outage. This was done primarily to assist in the removal of iodine (if needed due to fuel integrity) during system openings. The secondary effect has been to remove residual metal heat quicker from containment which obviously assists workers. We have tried cool vests, etc.; to help increase heat stress stay times for workers, but to date cooling off and hydrating have been the rigor d'jour. One other consideration that you might want to contemplate is using anticipated PCEs. Basically reduce the protective clothing requirements and trade off heat stress vs. contamination. Seth. From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Tuesday, October 12, 2010 6:25 AM To: [email protected] Cc: [email protected] Subject: Powernet: Cavity Decon Stay Times Limerick asked this question before and got no response. We are putting it out again for review. Rad Engineering is trying evaluate "out of the box" methods for increasing stay times due to heat during reactor re-assembly and cavity decon. Any information is appreciated. Limerick is a Boiling Water Reactor (BWR). Stays times for initial cavity decontamination activities during refueling outages are limited to 30 to 45 minutes due to temperatures. 1) Prior to reactor cavity drain down - What methods (other than shut down cooling) are used to control water temperature prior to drain down to reduce temperatures in the cavity post drain down? (Note: A large in-vessel inspection or repair scope may limit the use of shut down cooling.) 2) Post reactor cavity drain down - What method is used (if any) to control or reduce reactor cavity temperatures after drain down to increase stay times? (e.g., in-cavity air-conditioning, evaporative cooling fans). 3) If you don't do anything to reduce temperatures for worker stay times, please state that and why. You can respond via Powernet or contact our Rad. Engineer directly. [email protected]<mailto:[email protected]> or 610-718-2248. Thanks Linda Parlatore ************************************************** This e-mail and any of its attachments may contain Exelon Corporation proprietary information, which is privileged, confidential, or subject to copyright belonging to the Exelon Corporation family of Companies. This e-mail is intended solely for the use of the individual or entity to which it is addressed. If you are not the intended recipient of this e-mail, you are hereby notified that any dissemination, distribution, copying, or action taken in relation to the contents of and attachments to this e-mail is strictly prohibited and may be unlawful. If you have received this e-mail in error, please notify the sender immediately and permanently delete the original and any copy of this e-mail and any printout. Thank You. ************************************************** Email Firewall made the following annotations --------------------------------------------------------------------- --- 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. ---------------------------------------------------------------------
