Hi Doug, EPRI is looking at this in the chemistry extended activity release project. Most/all B&W and many CE plants don't because of tradition to have RCP's off after the pressurizer is solid or inability of the cleanup system to be in service.
We're still learning a lot here. Many Westinghouse plants oxidize before securing RCPs, usually with one pump but some have tried multiple pumps. Several are securing RCPs before oxidation now. The experiences vary, the main concern is whether the particulate activity fuel crud will be sheared off the fuel with the high flow rates and decreasing temperature (and oxidizing conditions), which could lead to contamination in the RCS systems. If there isn't much particulate activity, then one pump running is a good thing because you have good mixing and dissolution of the nickel fuel crud by the peroxide, and it can be removed by the cleanup system along the predicted cleanup curve. However, if there are two or more pumps running, you may increase the shear forces and distribute the activity, this can be a real problem, especially with recently replaced generators when there is a lot of nickel-based crud on the fuel. I've also seen channel head dose rates decreased where the pumps were run, but it's not guaranteed. In cases where you have high fuel duty (or a lot of local boiling) and no RCPs running (and sometimes with them running), you may have a lot of slow dissolving crud that leads to an extended release, or it takes longer than the theoretical cleanup curve. One B&W plant in particular and a serious case of this. We think it's related to the form of the crud on the fuel. This can also lead to more than normal activity in the transfer canal and fuel pool. You're welcome to give me a call about it, I'm traveling internationally next week. --Dennis ================================ Dennis Hussey Senior Project Manager Electric Power Research Institute, Nuclear Sector Fuel Reliability, Radiation Management, Chemistry Phone: 650 855-8529 Fax: 650 855-1026 Mobile-Work: 650 862-7387 [email protected] -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of [email protected] Sent: Wednesday, November 10, 2010 12:28 PM To: [email protected] Subject: Powernet: Use of RCPs during Shutdown clean-up Davis-Besse is a B&W 2 loop pwr. The station has never used its reactor coolant pumps during shutdown evolutions. We are considering it now. How many pwrs utilize rcps during crud burst clean-up. activities Douglas L. Noble Manager - Radiation Protection Davis-Besse Nuclear Power Station (419) 321-7780 office (419) 304-0068 cell ----------------------------------------- The information contained in this message is intended only for the personal and confidential use of the recipient(s) named above. If the reader of this message is not the intended recipient or an agent responsible for delivering it to the intended recipient, you are hereby notified that you have received this document in error and that any review, dissemination, distribution, or copying of this message is strictly prohibited. If you have received this communication in error, please notify us immediately, and delete the original message. ----------------------------------- Powernet - a service of the Health Physics Society Power Reactor Section Powernet archives at http://www.mail-archive.com/[email protected]/ Reply to: [email protected] If Questions, contact Mike Russell, CHP at [email protected] ----------------------------------- Powernet - a service of the Health Physics Society Power Reactor Section Powernet archives at http://www.mail-archive.com/[email protected]/ Reply to: [email protected] If Questions, contact Mike Russell, CHP at [email protected]
