ML13004A329
| ML13004A329 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 03/10/2010 |
| From: | Lawrence Criscione NRC/RES/DRA |
| To: | William Jones NRC/RGN-II |
| Shared Package | |
| ML130040225 | List:
|
| References | |
| FOIA/PA-2012-0259 | |
| Download: ML13004A329 (4) | |
Text
+3 Criscione, Lawrence From:
Criscione, Lawrence Sent:
Wednesday, March 10, 2010 4:30 PM To:
Jones. Willia Cc:
1(b)(7)(c)
Subject:
Dilutions during the 80F Temperature Transient?
Attachments:
CARS 200701278 on August 20, 2007.pdf; Letter to Steven Hill.pdf; MODE2 Shutdowns -
10-2003 and 6-2005.xls; CARS 200701278 - Attachemnt - Parameters during June 17, 2005 Shutdown.pdf; CARS 200701278 - Attachemnt - Shutdowns From Mode 2.pdf
- Bill, This is an email I sent to Steve Hill (of INPO) when I still worked at Callaway Plant.
Attached to this email is a spread sheet (all the attachments are the same ones sent with the original email to Steve Hill).
The Excel spread sheet shows dilutions occurring between 09:47 and 10:02 (during the time of the 8OF temperature transient), but this might not be accurate (see below).
The worksheets of the Excel file contain the actual Callaway Plant data from eDNA. The charts of the spreadsheet are a mixture of scaled data and actual data:
The IRNI traces are actual data plotted on the log axis
" The rod heights are actual data plotted on the linear axis
" There are two AT traces. One is plotted on the log axis and is scaled to lay on top of the IRNI plots.
One is plotted on the linear axis and is scaled such that one division is equivalent to 5% rated reactor power AND offset such that the 1 E-3 line is equivalent to 0% rated reactor power.
The Tavg trace is plotted on the linear axis and is scaled such that one division is equivalent to 5°F AND offset such that the 1E-3 line is equivalent to 5570F.
" Tref is scaled and offset similar to Tavg The Lpzr trace is offset to get it out of the way of the other traces
" The trace labelled "dilution" is actually "total makeup" flow.
The Excel spreadsheet contains data from the following two data points:
REF0110D, BORIC ACID PULSE INPUT REF0111D, TOTAL MAKEUP PULSE INPUT During the 12:49 to 13:00 time frame, both REF0110D and REF011 1D were going up, so a boration was occurring at this time.
During the 09:47 to 10:02 time frame, REF0110D was steady and REF0111D was going up. I took this to mean a dilution was occurring (since no boron was being added). I still believe this, but I no longer have access to the Callaway Plant documents to confirm this.
It may be that from 09:47 to 10:02, an automatic make up was occurring in response to lowering pressurizer level from the temperature transient.
Before you state that the RCS was not diluted within two hours of the temperature transient, I would make sure that the 09:47 to 10:02 make up additions were from some type of "make up" (i.e. blended flow set to match RCS boron concentration) and not from a dilution (i.e. pure water).
When I initially analyzed the data, I was under the impression that for a "blended flow", REF01 10D would rise.
I still believe this, but I might be wrong.
From: Crscione, Larry S.
Sent: Tuesday, August 21, 2007 9:58 AM To: 'hillsc@inpo.org'
Subject:
SOER 07-1 and Callaway Action Request 200701278 Please review the attached documents.
Thank you, Larry Criscione Shift Engineer Callaway Plant 2
August 20, 2007 Steven Hill, Events Analysis Institute of Nuclear Power Operations 700 Galleria Parkway Atlanta, GA 30339-5943 Mr. Hill:
I just finished reading SOER 07-1. In February 2007 1 analyzed eDNA (I do not know what the acronym stands for, but it is the Plant Historian system at Callaway Plant) for nine shutdowns from October 2002 through May 2006.
The data I looked at included rod bank heights, average coolant temperature, Pressurizer pressure, Intermediate Range Nuclear Instruments ion chamber amps and Delta T power.
In two of the nine shutdowns the operators intended to hold power in MODE 2 after descending from 100% power. Both attempts were unsuccessful. In each case, a temperature rise of a couple degrees Fahrenheit occurred upon tripping the turbine which inserted enough negative reactivity to shut down the reactor before the operators noticed the transient.
Since both cases involved a negative reactivity transient, reactor safety was never in jeopardy. Analysis of these incidents might still be of concern to you because:
" Although it does not jeopardize nuclear safety, the inadvertent shutdown of a reactor plant due to a positive temperature transient near the point of adding heat (POAH) can cause a loss of unit capacity. In June 2005 Callaway Plant lost 31 hours3.587963e-4 days <br />0.00861 hours <br />5.125661e-5 weeks <br />1.17955e-5 months <br /> of generation due to an inadvertent shutdown.
" Although a negative reactivity transient does not, in itself, jeopardize nuclear safety, the response to it of an inexperienced or ill-trained operating crew could result in a crew initiated positive reactivity event similar to the Zion and Surry incidents.
" At Callaway Plant there was a wide spread misperception among the operators that the two shutdowns were caused by Xenon.
- During the October 2003 shutdown, it does not appear the operating crew noticed the reactor had shutdown until nearly an hour after the event.
" At Callaway Plant there is a wide spread misunderstanding among the operators and supervisors that the Point of Adding Heat is at 1%. Although this is a good thumb rule for reactor start ups (RCP heat is about 1% power at Callaway), during the shutdowns analyzed the POAH occurred at about 2% due to decay heat. Also, the affects of the POAH (reduction in and finally loss of moderator temperature driven reactivity feedback) were present as early as 7% power.
The analysis was captured in Callaway Action Request 200701278. In response to this analysis, Operations has adopted the following; The steam dump automatic controller is set such that the steam dumps are approximately 5% open prior to tripping the main turbine (this eliminates the
-2°F temperature rise on tripping the turbine).
If the reactor will be retained critical following the turbine trip, low power operations will be conducted well above the Point of Adding Heat; power will be maintained between 7 and 14% on the steam dumps.
Please review the enclosed condition report and data. By plotting the log of Delta T power offset to IRNI ion chamber amps, it is readily apparent when the POAH starts to have an affect on moderator temperature driven reactivity feedback. Around 7% Delta T power, the log of Delta T starts to diverge from the ion chamber amps plot. By 2%
power (dictated by decay heat and pump heat), all temperature feedback to reactivity is lost since nuclear fission has a negligible contribution to the heat being generated by the system.
I am interested in your review of CAR 200701278 and appreciate any comments you might provide. The two shutdowns of particular interest are the October 21, 2003 and June 17, 2005 shutdowns. Both of these shutdowns occurred while tech spec required equipment was being repaired and the operating crews intended to maintain the reactor critical after tripping the turbine. Neither attempt was successful.
Respectfully, Lawrence Criscione Shift Engineer Operations Department Callaway Plant 2