My initial response was a camera or lighting issue based on just one picture. Looking at the two pictures (Capture1 and Capture2) where Capture1 is more in focus than Capture2, the distortion is much less. It looks more like thermal distortion in the water in addition to the camera angle and lighting. Beaver Valley had been performing 4-sided fuel inspection for several cycles with 4 cameras located on the refueling cavity floor pointing upwards slightly to record the assemblies as they are retracted into the mast. The thermals from the core and the fuel itself created some interesting pictures and videos.
Also, the Bottom Nozzles are 304 SS not Inconel. We did see a lot for discoloration of the bottom grid that is made from Inconel in our videos, but not the "cloudy" pictures you've seen.
We also identified very different crud patterns on fuel assemblies located on the baffle. Since there is a lot more flow turbulence and we utilize zinc, the crud patterns were very varied on the fuel assembly faces towards the baffle. We did not see any unusual patterns under the Bottom Nozzle, however the cameras we used were at an angle and not directly under the fuel assembly. I may go back and try to look at some of the videos for fuel assemblies right near the cameras to see if there were any similar patterns to yours.
Anthony (A.R.) Burger Supervisor, Reactor Engineering FENOC- Beaver Valley Power Station Phone: (724) 682-4108 Cell: (724) 601-3224 FAX: (724) 682-4250 Email: aburger@firstenergycorp.commailto:aburger@firstenergycorp.com
From: PWRRM [mailto:pwrrm-bounces@retaqs.com] On Behalf Of Elam, Kevin Scott Sent: Wednesday, March 29, 2017 9:02 PM To: Elam, Kevin Scott kselam@tva.gov; BRYSON, DAMON V DBRYSON@scana.com Cc: 'Kelliher, Andrew P:(GenCo-Nuc)' andrew.kelliher@exeloncorp.com; pwrrm@retaqs.com Subject: *EXTERNAL* Re: [Pwrrm] FW: question on fuel assembly bottom nozzle observation
Is the issue related to the angle at which you view the bottom nozzle? Absolutely. But that does not mean the phenomenon is a camera or lighting issue. We have quite certainly refuted that notion.
My best analogy is parking a DeLorean in a lit parking lot at night and placing a piece of gray, fine grained sandpaper on the hood. When you move such that the sandpaper is aligned with the reflection of a light, you do not see the image of the light. You see a slightly brighter shade of the gray sandpaper. When you move such that the sandpaper is aligned with a portion of the hood reflecting the black sky, you see a slightly dimmer shade of the gray sandpaper.
The majority of the light reflected off of the surface of the bottom nozzle is reflected in the normal way off of the surface. But there is a significant portion of the light that is reflected in a scattered manner. I would also suggest that there might be some preferential angle of reflection.
I have two theories:
* There is a microscopic layer of something adhereing to the bottom nozzle, probably chemically induced, such as an oxydation mechanism. The molecules thick substance has unique reflective properties. Scattering, mostly.
* There are microscopic pits in the surface of the bottom nozzle, possibly caused by microscopic "sand-blasting."
Why it is not a lighting (or camera) issue:
* The phenomenon is correlated to fuel assemblies adjacent to the core baffle.
* The shape of each image on each fuel assembly is defined. No matter how you spin or move the fuel assembly, the shape remains the same.
* Another way of thinking about it is the image does not exist on a bottom nozzle, or half of a bottom nozzle, it never appears no matter how you spin or move the fuel assembly.
* If you pick up a fuel assembly multiple times and look at it, the shape on that fuel assembly is the same.
* When you watch the image in motion, you can see it is associated with the bottom nozzle and not the light source in the canal. When you bridge the fuel assembly so that you change the angle of sight from about 40o to about 5o, the surface image actually does not entirely go away. You see the image fade, but it is still slightly there at the nearly vertical angle.
* The effect exists on the inner surface of the flow holes, which do not directly reflect the light from a light source in the canal. The light reflected from the inner surface of the flow holes is highly scattered - looking lighter when it should be darker and looking darker when it should be lighter. In other words, just slightly verying shades of medium gray, no matter how the surface aligns with your camera and light source.
Seeing these images in motion with video is much more enlightening than seeing still shots.
Why it is not my second theory of microscopic pits in the surface:
* This phenomenon does not affect the shiny stainless steel screws mounted in the bottom nozzle. If it were a "sand-blasting" phenomenon, I would think the screws would have also been pitted.
Why I think it is a chemical attack:
* The bottom nozzle is Inconnel and the screws are stainless steel. The phenomenon is differential to the material. I think it is some kind of chemical reaction that affects inconnel and not stainless steel.
Kevin S. Elam
Reactor Engineer kselam@tva.govmailto:kselam@tva.gov 423-365-8806 Watts Bar Nuclear Tennessee Valley Authority
From: PWRRM [mailto:pwrrm-bounces@retaqs.com] On Behalf Of Elam, Kevin Scott Sent: Wednesday, March 29, 2017 3:42 PM To: BRYSON, DAMON V Cc: pwrrm@retaqs.commailto:pwrrm@retaqs.com Subject: Re: [Pwrrm] FW: question on fuel assembly bottom nozzle observation
TVA External Message. Please use caution when opening. The effect is a real surface issue on the fuel. Not a camera or lighting issue.
Sent from my iPhone
On Mar 29, 2017, at 09:46, BRYSON, DAMON V <DBRYSON@scana.commailto:DBRYSON@scana.com> wrote:
TVA External Message. Please use caution when opening. That looks like some kind of weird combination of a reflection and difficulty focusing. I agree, it's not a problem with the fuel. You might be able to eliminate this with a lighting adjustment. It is not unusual to see strange artifacts on these digital cameras. It also might be a problem with the thermals adjustment, if you have that feature on your camera. I love the thermals adjustment when doing ID verification in the core, but it can do some weird things.
Damon Bryson VC Summer Nuclear Station dbryson@scana.commailto:dbryson@scana.com 803-345-4814
From: PWRRM [mailto:pwrrm-bounces@retaqs.com] On Behalf Of Hulvey, Kimberly Dawn Sent: Tuesday, March 28, 2017 8:56 AM To: 'pwrrm@retaqs.commailto:pwrrm@retaqs.com' <pwrrm@retaqs.commailto:pwrrm@retaqs.com> Subject: [Pwrrm] question on fuel assembly bottom nozzle observation
***This is an EXTERNAL email. Please do not click on a link or open any attachments unless you are confident it is from a trusted source. ________________________________
During our refueling outage fuel assembly inspections, we noticed something unusual in a number of periphery fuel assemblies removed from the core. We initially thought it was some type of debris and were going to attempt removal. Upon further inspection, the 'marking' is only seen at certain angles of viewing - it looks like a haze. Since we have seen this on more than one assembly, we don't think it is camera distortion or camera focusing issues. When we zoon in and look at the flow holes better, we do not see any obstruction so we are currently planning to reuse these assemblies. Just curious if anyone had ever seen anything similar. Pictures are attached.
Thank you in advance for your response and help.
Kim Hulvey WBN Reactor Engineering Manager 423-365-7720 (office) 931-581-5423 (cell)
<Capture4.JPG> <Capture3.JPG> <Capture2.JPG> <Capture1.JPG> <why we had concern.JPG> <Capture6.JPG> <Capture5.JPG> _______________________________________________ PWRRM mailing list PWRRM@retaqs.commailto:PWRRM@retaqs.com http://www.keffective.com/mailman/listinfo/pwrrm _______________________________________________ PWRRM mailing list PWRRM@retaqs.commailto:PWRRM@retaqs.com http://www.keffective.com/mailman/listinfo/pwrrm
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