ML13004A327
| ML13004A327 | |
| Person / Time | |
|---|---|
| Site: | Callaway  |
| Issue date: | 11/03/2010 |
| From: | Lawrence Criscione NRC/RES/DRA |
| To: | David Beaulieu Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML130040225 | List:
|
| References | |
| FOIA/PA-2012-0259 | |
| Download: ML13004A327 (5) | |
Text
Criscione, Lawrence From: Criscione, Lawrence Sent: Wednesday, November 03, 2010 3:26 PM To: BeaulieulQvid Attachments: ]testimony
& NRC conclusions.pdf Dave, fro4(b)(7)(C)
I have attached an Adobe document to this email. The first two pages of that document come fromIi testimonyF(b)(7)(c)
It is very evident from his testimony that he believed the temDerature decrease was caused by fault steam line drains. This is also backed up by statements made durindb)(7)(C) j testimony b)(7)(C) land by the NRC in the 01 investigation summary for Case 4-2007-049.
It is also backed up in Callaway Plant CAR 200308555 which blamed the letdown isolation on a cooldown caused by faulty steam line drain valves and it is also backed up by a Callaway Plant work order (mentioned during the testimonies) for troubleshooting and repairing the steam line drain valves. By their own admission, the crew certainly believed on October 21, 2003 that the cooldown was the result of malfunctioning steam line drain valves. And in 2007/2008 the NRC concurred with this view and so did I. The last two pages come from a February 26, 2010 letter from Region IV to me. In this document, it is clear that the NRC now understands that the temperature transient was due solely to the buildup of Xenon and had nothing to do with the opening of the steam line drains. I initially was resistant to this view, but have since "seen the light". Callaway Plant, however, is still "in the dark" and it is important to elucidate the facts. I am not hard and fast that this needs to be apparent in the Information Notice, but I do believe including it adds to the information being conveyed.
With the reactor critical and well above the point of adding heat, opening the steam line drains should have merely caused a slight increase in reactor power and not affected temperature at all -the temperature drop was solely due to Xenon-135 building up.Lawrence S. Criscione Reliability
& Risk Engineer RES/DRA/OEGIB Church Sireet Building Mail Stop 2A07 (301) 251-7603 36 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 551 degrees.(b)(7)(C) iOr higher?(b)(7)(C)
IOr higher. That's minimum.l(b)(7)(C)
So what kind of action do you have to take if you go below the 551?1(b)(7)(C)-
1i have to restore temperature above 551.(b)(7)(c)
IWas that recognized?
Was there an attempt to restore temperature?
I(b)(7)(c)
Well, yes. We tripped the turbine.1(b)(7)(c) 1Okay.(b)(7)(C)
IWe initially
-- in going back through, we had opened up our steam dump drain valves -- or not our steam dump drain -- our drain valves on the steam lines, and that's when we started having -- when the temperature started to lower.The balance of plant operator closed those drain valves to restore temperature.
We got dual indication in the control room that not all the drains were closed. We tried to reduce the blowdown flow --the steam generator blowdown flow. And then we tripped the turbine.Ib I Was that successful in getting the temperature to come back above the minimum NEAL R. GROSS COURT REPORTERS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., N.W.I.3,O\ 'Y2A.A.ii WA miw41N1f n f .mfl -w.,I7fI www rrxlmrnwt rin 37 1 temperature for criticality?(b)(7)(C)2 Ij Tripping the turbine was.3 PIc Okay.4 (b)(7)(C)
IThe drain valves -- I don't 5 know how familiar you are with our drain valves, but 6 probably one hand switch controls, I think, 13 7 different valves.8 So we had E~s out in the field trying to 9 find which drain valves were still open. We closed 10 those, and then we were trying to maintain some steam 11 generator blowdowns.
We were throttling blowdown.
And 12 we did eventually trip the turbine.Ib()(C)13 So you did have -- aside 14 from the inverter, you did you have some other 15 equipment fail, drain valves?(b)(7)(C)16 Drain valves, correct. But 17 I didn't know that until --(b)(7)(C)18 Later.19 Correct.(b)(7)(C)20 Okay. Do you understand 21 what he's saying? He's saying that they had some 22 equipment fail that got them into the condition
-- the 23 Tech Spec for minimum temperature for criticality.
24 (b)(7)(C)
= Okay.I[b)(7)(C)
I 25 So that put them there, NEAL R. GROSS COURT REPORRS AND TRANSCRIBERS 1323 RHODE ISLAND AVE., NW.(2021 234-4433 WASHINGTON, D.C. 20005-3701 www.nealrgou.comn performing the reactor and steam piant shutdown orocedlures.
Tile inspection reviewed the details of these procedures and concluded that the operators followed the procedures correctly and had maintained the plant in a safe configuration with adequate shutdown margin The inspectors evaluated the time that elapsed from when the reactor went sub-critical to the time the contro' rods were fully inserted into the core. The inspector.
found that not inserting the control rods soon after the reactor went sub-critical was not consistent with effective command and control and good piant oper:alionali awareness.
The NRC mnspectcrs also determined that the delay :n :o iet~nv the shutdown by tnset~ina tie control rods was not a"l jnsafe condition The nspec.ors verified that no ctrocedurai outdance e-,:isied wito1 respect to nrrleniness as to how fast the c:;ontrol rods needed ro be inserted The inspectors noted mhat the crew had completed a shutdowri rmargin verification just prior to trrppin. the main turbine, as required by the shutdown procedure.
The shutdown margin verification ensured that had a design basis arcident occurred at that time, adequate negative reactivity was available to maintain the plant shutdown.The NRC's Office of Investigations Region iV Field Office, nitrated an investgaturx to determine there was ,,fi,, misconduct in the ,o"trol room orsonnel"s fa1Lre to document the ,ern..erature .ransient.
On November 6. 2007.. the NRC staff met wth you to investigate whether there was wilfj.i misccrnduCi in tile -ccntroi oroom verscinet'5 41iue to documenl the te-nperature lransient.
The investigator also interviewed 11 indiv.duals who were kn I deabe of facts pertinent to your concern, inch.iding thel(b)17)(C)(b)(7)(C) on duly dur ng tlhe October 21, 2003, shutdown.
Based onl the evidence developed dliinnlgtne investigation, the Office of Investigations deleimined the allegation that control roomTl personnel at the Callaway Plant willfully failed to document a temperature transient on October 2 1. 2003. was not substantiated.
Based on the NRC's assessment of the October 2003 sihutdown:
10he opera.',ng crew -did not anticipate the impact of the rapid; shutdown frorm the reactwvity mana. )ement perspective which th~en resu!!ed in ra"s'is osre the t al 'he ;o, power cceran ieveis The iýnspectors performed a reactivity balance for severai periods of tin-e associated wvilh the shutdown i.t bette: understand what was controlling the power of the reactor The NRC assessment of the transient was that operators did not recognize that the reactor was responding to the steady state main turbine demand through the reactor coolant system termperature decrease, which then caused the decrease in pressurizer level and the letdown system isolatiorn.
Xenon was controlling the shutdown rate of the reactor for at. least " ho urs pfor to :he turbine trip and fo!Iowino the las t con.:nre "od ,srto i:,er turlbine p, 0h- reactor *oant .s~en tenmoerature increased to the !." eeve; adding negatve re!ctity.
Ti, -.s. aloni wvh the Xencn accumuLiatiorn, sh-ut the r...eactor down and conltinued to Olcrenise the shutdown marcin until the conitro! rods were cm. eteh; tserted The NRC determined that the temperature and pressurizer level transient just prior to the turbine trip was caused by the negative reactivity being added by the Xenon. Because Xenon continued to build in rapidly and insert negative reactivity during the down power from 100.percent power when operators attempted to stabilize the reactor power with a constant main turbine load, a temperature transient .decrease, co! the reactor plant occurred providing RIV-2007-A-0096 E2ctosure RIV-2009-A-0036 the necessary positive reactivity to maintain power As a result of the temperature decrease, there was also a decrease in the pressuimzer level and the subsequent letdown soiation.Earlier, Control Banks C. and D had ee' nser.ed aio-rý wih a red.cion in turbine load to baiance reactoi and tuirblne oer levels to approximately 7-percent Vhe NRC performed an approximate reactiity baiance for the reactor at the po;nt where average temperature JTavq)began to decrease.
The reactivity balance indicates that the continued buildup of Xenon poison in the core without a corresponding reduction in turbine load caused the decrease in Tavg and related plant responses The NRC found that the temperature transient that resulted in the core temcnerature falling below the mirimum Techr.ical spec-!.caton-.O re,. 'ed temperature for cnt!,caiily wvas relui redto e eyed n,,. the censees cc~rectfve
- .wtn oi'gram. The NRC documented trhe associale, non-;te. vo~at~on in. NRC Insoecton Report 05000483,2007003 It. addition, the NRC resident insrdciors at the Callaway Planl commun-icated NRC perspectives regarding the operating crew's performance, including the command and control aspects of the evoluLtion, with Callaway Plant management The NRC found .that reactivity r.anagerment at the low power levels.. where the plarnt configuration induced the plant transient to maintain reaclcr oower, was not effective or adequately supported by procedures, and ta!I tripping 1the main turbine andfor reactor could have pievented the temperature and pressurizer level transient.
The NRC noted that the pre-evolu&Con practice training provided to the operators did not include operation after thte point where the opera.iors tripped the main turbine.tf~~ff-rcrrutdq*and Prcceluries an-d Tra rvrinc linoacts and movnet The inspectors reviewed the iicensees training materials to detemi.ne how the licensee addressed activities and lessons learned from the October 2003 unit shutdown.
The licensee did not demonstrate appropriate awareness of reactivity implications based on their actions and!he plant configuratvon, including the impact of Xenon with a steady main turbine power output a'd later ma~nl.ai..nq the control rods ith:Javrn after t -c',ant: was shuti r! own -he inspectors no.e:t thai orel atom trainino fnr low n,,er d'cd rnt a-den.iate!y address thrimpact 3f systemfrr .esponses.
conrrnamcd and control with procedura" *rpre enta1~ozn, and re(activitjy managernerni The inspectots reviewed both initial license trainin., and lice-rnsed operator contnuing train'ing materiais as it is currently being implemented The inspectors identfied that both the initial license and licensed operator continuing trainir' incorporated plani shutdowns from. a iow power of 20 io 3QC percent power to a Mode 3 condition.
Thns "rainin Inclu.,ded both siimulato-and classroom on the performance of the task and the ecessary procedures to accomplishment the evolution.
Emphasis was placed on (the actionis required by the procedure and the sequence of these actions, In addition, the licensee crealed a job performance measure for the licensed operator continuing training to prepare a Xenon prediction for changes 0t power The kicensee also h-as performed several pre.evolution practrce-tra;iinng activwties fir vnrl a. ... ., , ul-n,, during plant sa.,0lup arId shutdown ar,, Want. er rh ge c ; eou ,,, Ulo..re RIV-2007-A-0096 RIV-2009-A-0036