ML110620527

Lr - FW: Information Request - Diablo Canyon - Neutron Noise

ML110620527
Person / Time
Site:	Diablo Canyon
Issue date:	12/21/2010
From:	Office of Nuclear Reactor Regulation
To:	Division of License Renewal
References
Download: ML110620527 (4)

Text

DiabloCanyonNPEm Resource From: Poehler, Jeffrey Sent: Tuesday, December 21, 2010 10:00 AM To: Cullingford, Michael

Subject:

FW: Information request - Diablo Canyon - Neutron noise Jeffrey C. Poehler Sr. Materials Engineer NRR/DCI/CVIB (301) 4158353 From: Parks, Benjamin Sent: Monday, December 20, 2010 12:16 PM To: McLellan, Thomas; Poehler, Jeffrey Cc: Wang, Alan

Subject:

RE: Information request - Diablo Canyon - Neutron noise Im afraid I have little to add.

A number of different effects could be causing neutron noise. In the Diablo case, looks like it was vibration.

In other cases, Westinghouse plants have been known to undergo an upper plenum anomaly where temperatures fluctuate, causing power oscillations and mild xenon transients. In BWRs, some plants undergo bistable flow oscillations in the header cross region of the jet pumps, which propagates into power oscillations picked up by the LPRMs. These noises have a pretty long period, though on the order of minutes.

Perhaps the RIV/DRP folks could shed some light on the regulatory interaction described in the NEI article, but in the other two noise examples I identified, there was no regulatory interaction that I am aware of. One of the bistable flow plants, I know, had to reduce its thermal power level to avoid the oscillations resulting in an overpower condition in excess of their operating license. The upper plenum anomaly plants work their issues out in control space its a bigger problem with 14 cores.

From: McLellan, Thomas Sent: Monday, December 20, 2010 9:50 AM To: Poehler, Jeffrey Cc: Parks, Benjamin; Wang, Alan

Subject:

RE: Information request - Diablo Canyon - Neutron noise Try Benjamin Parks of the Reactor Systems Branch we work with him a lot on various relief requests. From the attached article sounds like a turbulent flow issue. Tom From: Poehler, Jeffrey Sent: Monday, December 20, 2010 8:04 AM To: Cheruvenki, Ganesh; McLellan, Thomas; Fairbanks, Carolyn; Sheng, Simon; Andruszkiewicz, Edward; Widrevitz, Dan; Sydnor, Christopher; Purtscher, Patrick; Kerr, Matthew Cc: Mitchell, Matthew

Subject:

FW: Information request - Diablo Canyon - Neutron noise Have any of you ever reviewed anything related to neutron noise monitoring? Im thinking this is something Reactor Systems Branch in DSS or I&C Branch in DE would be responsible for, but I thought I would check with you all first.

1

Thanks, Jeffrey C. Poehler Sr. Materials Engineer NRR/DCI/CVIB (301) 4158353 From: Wang, Alan Sent: Friday, December 17, 2010 3:53 PM To: Poehler, Jeffrey

Subject:

FW: Information request - Diablo Canyon - Neutron noise Jeff, I got the Matt is away message. Could you help me with this. Thanks alan From: Wang, Alan Sent: Friday, December 17, 2010 3:51 PM To: Mitchell, Matthew

Subject:

FW: Information request - Diablo Canyon - Neutron noise Matt, Mike Cullingford had this request from someone from the Spanish NRC?. They saw the Diablo article and was wondering if it might have implications for them. I am not sure what issue with the Trillo plant is but when I read the link it appears to me that the neutron noise was instrumentation we placed inside the reactor to look for vibration and loose parts. Do you know if we have any information regarding this type of instrumentation to determine vibration or loose parts? It is not clear to me what neutron noise they are detecting unless they too are using a similar technology for loose parts. If you have any insights on this I would appreciate it. Alan From: Cullingford, Michael Sent: Friday, December 17, 2010 9:49 AM To: Wang, Alan

Subject:

FW: Information request - Diablo Canyon - Neutron noise Hi Alan: Could you please guide me as to who is the appropriate person (if not yourself) for me to get the answer to this question? Thank you, mike From: FRANCO MATILLA, Fernando [1]

Sent: Friday, December 17, 2010 4:48 AM To: Fehst, Geraldine

Subject:

Information request - Diablo Canyon - Neutron noise

Dear Gerri,

On behalf of one CSN Commissioner, we are interested in obtaining some technical information from the NRC. As you may know, we have been experiencing abnormal neutron noise in Trillo NPP. The analysis carried out by the licensee and the CSN is under progress, with the cooperation of our German colleagues (Trillo is German design), who are carrying out similar analysis. In relation to this, the following news has drawn our attention:

http://www.neimagazine.com/story.asp?storyCode=2056532 We would be interested in obtaining some information about the role of the USNRC in case it has been involved in the assessment of this issue. So far, our search at the USNRC website has been unsuccessful. Would it be possible to get additional information regarding the evaluation of this situation by the NRC? Thank you very much for your cooperation, Fernando Franco 2

3 Hearing Identifier: DiabloCanyon_LicenseRenewal_NonPublic Email Number: 2638 Mail Envelope Properties (Jeffrey.Poehler@nrc.gov20101221100000)

Subject:

FW: Information request - Diablo Canyon - Neutron noise Sent Date: 12/21/2010 10:00:23 AM Received Date: 12/21/2010 10:00:00 AM From: Poehler, Jeffrey Created By: Jeffrey.Poehler@nrc.gov Recipients:

"Cullingford, Michael" <Michael.Cullingford@nrc.gov>

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Files Size Date & Time MESSAGE 4989 12/21/2010 10:00:00 AM Options Priority: Standard Return Notification: No Reply Requested: No Sensitivity: Normal Expiration Date:

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