U-604453, Regulatory Conference Information
| ML18334A179 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 11/19/2018 |
| From: | Kapellas B Exelon Generation Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation, NRC/RGN-III |
| References | |
| U-604453 | |
| Download: ML18334A179 (54) | |
Text
{{#Wiki_filter:Exelon Generation Clinton Power Station 8401 Power Road Clinton, IL 61727 U-604453 November 19, 2018 Regional Administrator, Region Ill U.S. Nuclear Regulatory Commission 2443 Warrenville Road, Suite 21 O Lisle, Illinois 60532-4352 Clinton Power Station, Unit 1 Facility Operating License NPF-62 NRC Docket No. 50-461
Subject:
Clinton Power Station Regulatory Conference Information
References:
(1) Letter from P. L. Louden (NRC) to B. C. Hanson (Exelon Generation Company, LLC), "Clinton Power Station-NRG Inspection Report 05000461/2018051 and Preliminary White Finding," dated October 15, 2018 [EA-18-104] (2) Letter from P. L. Louden (NRC) to B. C. Hanson (Exelon Generation Company, LLC), "ERRATA-Clinto n Power Station-NRG Inspection Report 05000461/2018051 and Preliminary White Finding," dated November 6, 2018 [EA-18-104] (3) Letter from B. T. Kapellas (Exelon Generation Company, LLC) to K. K. Stoedter (NRC), "Response to NRC Inspection Report and Preliminary White Finding," dated October 19, 2018 (4) Letter from K. R. Riemer (NRC) to B. C. Hanson (Exelon Generation Company, LLC), "Clinton Power Station~Regulato ry Conference," dated November 15, 2018 [EA-18-104] In accordance with the referenced letters, Exelon Generation Company, LLC (EGC) is submitting the enclosed supporting presentation materials for the Regulatory Conference to be held on November 30, 2018, at the NRC's Region Ill Office. As requested in References 1 and 2, this material is being submitted at least one week prior to the conference in an effort to make the conference more efficient and effective. There are no regulatory commitments contained in this letter. K C,Y'--J D~ rJ (Lf?__. (L~10-: ~rr
U. S. Nuclear Regulatory Commission U-604453 Page2 . If there are any questions or concerns regarding this submittal, please contact Mr. Dale Shelton, Regulatory
. Assurance Manager, at (217) 937-2800.
Respectfully, ley T.
- apellas Plant Manager Clinton Pow~r Station
Enclosure:
Clinton PowerStation Regulatory Co.nforence Information cc: NRC Document Control Desk NRG Proje.ct,Manager, NRH - Clinton Power Station NRG Senior Resident Inspector---'- Clinton Power Station Karla Stoedter.- NRG *
- Kenr'leth Riemer'-'- NRG Charles Phillips - NRG Illinois Emergency Management Agency- Division of Nuclear Safety
ENCLOSURE Clinton Power Station, Unit 1 Docket No. 50-461 Facility Operating License No. NPF-62 Clinton Power Station Regulatory Conf~rerice Information
.. 1 I
. I
* '. I
.' ./
I! *: Clinton Power Station . . i; :: ',
- c'~
Regulatory Conference ' . ', ,".. I ' , * ~
* ' * ,! * * ' .* 1 _* -;. ~ ' :; ,
- JI' ~* .' *
' . ~ .
'
- 1 - ' ,,.;
Divis*ion 2 Diesel Generator * - : - ****,: -* . " . . ' . ' . . . - . ' .' ' ~ ; ,, , Air Start Isolation .. - ' - - Event *. **. ** .* . *. *. **.* *. ; ' \ *. <
' ' ,, .. ' __ .-.... :1
., ; -. ' .... ~
.~ .-
November 3d, 2oi8 .* . *.**. .... .
.! '~ .,:
*,. ~- . . - '!
' . :_:* ' ' "/.*. . . ' :.~: . ' . *, . d 1
-' . ' :. - '-. . ~ . . ,.* . - '
/ ' -. *-* ' ,, ...
- ,_ )..-
- :'..,:..'. . <_ .. "**:. ~~----**-.:~*; ~-~-~ ... ~-*-~: ...*... -- ,'--'**- ~~:. ----~-'-"_*'. -
Agenda '*.J., 0 Introduction ... 0 di ,,?, ,II **11 Ill, IS
- II 111 ~. *: 11_,11- ,II Key Differences.
* .'In' itiar
. . Con : .*. ,: n*s<. Jolt
. ditio >\ '. ' . . ,, ' "' .*.Ev:e:nl
>** :,f).ostula:ted ,* ' ' . 1 and Mitigation ~ctiQ¥1S::.:* .............
8
-*Risk Slg_n-ffic.ance-~,~,::'/,;
.. ;::..,@:ehe.:.:Ke,ll'i
- ~~*ConcJu.sio.n II ***, '! '. ii .,11.
*)~e:a. Stfanei:,;* .
Clinton Powe.r Station Regulatory Conference Introduction Brad Fewell Senior Vice President, Regulatory Affairs and General Counsel Exelon Generation
"< ,e -
)__~*-~**-** -"~---~--- "----*~-------,-*-' -*-.r*---,--w--*-*---*---*-- ,_..._
Introduction 0 We agree with the Finding and violation 0 We recognize our failure to maintain the configuration of an important safety system 0 We have taken tirnely, comprehensive, and broad responsive actions 0 We disagree with the Finding's preliminary significance of White
- Commission Policy and NRC guidance drive risk evaluations to be realistic and based on best available information
- NRG risk evaluation does not reflect the as-built, as-operated plant response
- NRC's risk evaluation assurnptions do not reflect how CPS would respond to DG I
recovery, SBO, FLEX, and ELAP by not appropriately crediting: iI
- Operators' extensive knowledge, training, and experience I I
I
- Available time to take recovery actions Il
- Procedures that control the event and drive successful resolution I l
I
.::* '.P.RA ~~aluation~ should be reaiistic*:ahd *-based* on best available *information *.
< ~
* , I I
I 3 _..ft' Exelon Generation I
Introduction (cont.) 0 We will show that using realistic and best-available information: *
.i - Division 2 DG would have been restored and injection availa.ble within one hour I - Expansive time was available to recover AC power and prevent core uncovery - Procedurally directed alternati_ve power recovery actions would have been pursued in parallel - Objective data to support different performance shaping factor (PSF) multipliers
- We will provide information that the NRC did not previously review and nevv I
information that we have recently developed ) e We had the knowledge, time, and resources to' restore AC power and injection I I
*I I
I I I
- * . * =-~-,. * -** : ~ :* *Fin<;ting~~ould~be*.ch~r~qterized as Green* . ..*.- .. . ** .! I
* *
- i' ~ *
.I 4
~<"~ Exelon Generation **1!;
.. I
Clinton Power Station Regulatory Conference Finding Cause and Corrective Actions Brad Kapellas Plant Manager
, > Exelon Generation
Station Event Response 0 Root Cause
- Contrary to Exelon fleet governance for plant status control, operator logs were utilized as the sole means to track plant configuration
~ Corrective Action to Prevent Reoccurrence
- Identify and eliminate legacy site-specific administrative procedures/guidance that allow operator logs as a sole method for plant status control
~ Continuous Procedure Use
- Cause of the event was not an operating procedure execution issue - Procedure directed operator component rnanipulation error rate is very low (estimated less than two per million manipulations)
- Corrective Actions
- Implemented I know because I loo~,ed" initiative station wide to improve administrative procedure knowledge and compliance
- Reinforced accountability for equipn1ent status control throughout operations
- Revision to safety related operator rounds points
- Three day station wide campaign for change
.. Eve.nt taken s~riously and being used as burning platform to move
'J* . .. * .* ~
i
. culture to "sustained levels of high Operational Excellence .
I
~
6
...,..., ExelonGerleration. j
Clinton Power Station Regulatory Conference Key Differences Gene Kelly Sr. Manager, Risk Management Johnny Weissinger Di rector, Operations
) ., . y Exelon Generation
Exelon and NRC Risk Results - *Differences Exelon change in CDF NRC change in CDF 3.8E-6/year ' 0 Large difference in our results a factor of almost 400 1 I i i The difference is not in PRA methods ... both use similar approaches from a PRA
- standpoint
- Key differences:
- Actual site response in SBO conditions - Available time to recover power and injection I i - Operator experience and training applied to recovery actions - Complexity associated with power recovery actions
- I I
. . . I
- Risk analysis should refle.ct m.~nnerJn which plant is operated .
- II 8
Exelon Generation,~* jI I
Key Choice Letter Disagreements NRC Position Exelon Position Assumption 12 o 1 hour available to recover AC power to Division c Air start valves found isolated within 29 minutes; 2 by recovering DG; ELAP declared at 1 hour and ELAP not declared FLEX power to Division 2 would commence c DG recovery complicated by SBO load shedding o Load shed recovery proceduralized and does not that removes all DC control power from DG cornp.licate DG recovery FLEX electrical lineup impacts DG components J_o_. --E.-LA_P_no_t_d_e_c_ia_r_e_d/_F_L_E_x__s_ta_g_i_ng_o_n_ly-------1 Assumption 13 ~ Experience/training considered Low for DG DG air start valve position easily identified in recovery diagnosis knowledge-based or procedure-based mode
- Operators have not trained on, experienced, or ~ Operators extensively trained on DG rnalfunctions been exposed to failed DG LIii" 9
~* Exelon Generation
Key Choice Letter Disagreements (cont*.) NRC Position Exelon Position Assumption 2 .. 0 Time to TAF does not appear to credit shutdown Cl Operators will close one shutdown cooling valve cooling isolation per procedure to extend time to TAF from 10.8 hours to about 24 hours Assumptions 14, 23, 24 I
@ FLEX in1plementation success credited as Low 0 NRC inspections confirm that FLEX strategy meets regulatory !'equirements a FLEX lineup experience/training considered Low 0 FLEX trained in accordance with Systernatic .
Approach to Training G FLEX ergonomics considered Poor 0 FLEX tasks similar to norn1al EO tasks & . performed in non-adverse conditio"ns Assumption 15 e Div 3 to Div 2 AC power cross-tie is Complex 0 Procedure is straightforward and not complex f, Time required to complete cross-tie is 5-6 hours 0 Time-validated at 1.5 hours 10
~ Exelon Generation
Clinton Power Station Regulatory Conference Initial Conditions for Postulated Event, Recovery and Mitigation Actions Johnny Weissinger Director, Operations Gene Kelly Sr. Manager, Risk Management
-= 21 y* Exelon Generation
Success Criteria lpj~ctlon Establlshed Before RPV Water Level R~ac.hes the Top of .*. ii j Active Fu.el * *I I i : i'
.I Division 2 DG is completely recoverable (no equipment malfunction) and .I l
I operations response would not con1plicate recovery . i
- NRC did not model or credit Division 2 DG after one hour I!
I One action to close a shutdown cooling valve (1E12-F008), as directed by -I procedure, extends the time to TAF to about 24 hours
- Does not appear to be modeled in NRC's analysis I I
D*C batteries provide ability to control RPV pressure using SRVs. permitting
. II use of low or high pressure injection sourqes - Does not appear to be modeled in NRC's analysis I
.12
/lllllll6!Jl' . Exelon *Generation I I
I Exelon Perspective 0 RPV injection will be restored prior to reactor water level lowering below TAF through multiple, independent, and diverse means
- Rule-based procedural guidance to restore the DG - Knowledge-based identification of the DG air start valves - Cross-tie of the Division 3 DG to t!1e Division 2 bus - Use of FLEX
- Identifying the closed air start valves, reopening them, and restarting the DG per procedure terminates the postulated event
- Significant time available before deterioration of plant conditions
- Operators are extremely knowledgeable and experienced with DG operation
- All actions to identify the valves and restart DG are proceduralized
- Air start valves are readily identifiable and accessible
- Reopening a manual ball valve is a simple task
- Emergency battery lighting and portable flashlights available
- _Significant resources onsite to support 13
,.,,.,,.. Exelon Generation
Bus Alignment During Div 1 & 2 DG Unavailability 345 kV Switchyard - - ~ ~ Plant is in Mode 4 - Cold Shutdown RAT - B XFMR RPV Water Level 235" to 250" above TAF Time To Boil --4 hours Divis. 60V Unplanned out-of-service Div 3 DG Div 2 DG Division 1 138 kV Switchyard - - ~ ~ ------- AC Distribution X AC Distribution 0 AC Distribution 0 Diesel Generator X Diesel Generator X Diesel Generator 0 ERAT XFMR RHR-A / SDC X RHR-B / SDC 0 HPCS X LPCS X RHR-C 0 DC Batteries 0 DC Batteries 0 DC Batteries 0 14 Exelon Generation
Overview of Station Response to a SBO Power Recovery :
. . Shutdown *Cooling Restore Offsite
- Isolation Power *
'(extends time to
- TAF from 10.8 hrs to -24 hrs)
Align Div_2 DGto start Div 3 DG cross-tie to Div 2 bus FLEX 15 Exelon Generationoi
Loss of AC Power Procedure 4200.01 Station Blackout (SBO) <<cM- 1>> A t o tal loss o f o f fs i t e AC power sourc e s (i ncluding main gen erato r ), and fa i lure o f Div 1 & Di v 2 DG power source s. 1.5 Extended Loss of AC Power (ELAP) A tot a l and sustai n e d (> 1 hour) loss o f both o f fs i t e and ons ite AC power source s as a r e sul t o f a p os t u lated Be yond Des i gn Basis Externa l Event (BDBEE) which is e xpected to e xceed the 4 hour SBO coping p e riod .
- Definitions are in accordance with CPS licensing basis SBO is not a beyond design basis external event 16
!l
,*' .)
' i i
*/
.. i IF Within 1 HOUR of the Station Blackout, there has *I I
not been action taken that would provide a HIGH ASSURANCE of restoration of Div 1 and/or Div 2 power within the 4 hour SBO coping period, THEN STOP executing Station Blackout actions and immediately execute CPS 4306.01 Extended Loss AC Power/Loss of UHS. HIGH ASSUBANGE thi;lt ~;wer will*bercover<::;Clwithin4 hourq,in~lf.1.Q~::;:'.: ;. *. . . *. . . .
' *.**::. *:*.: .. *: .'.'*****:'* ....* .< * ..* ' .. :* .... :,..... *,, .... *~****,,:::*,*;*,_***.* ... ::*.*.. *: .. :.***' ._*,_.::.,_:._ . ,.:* ~.***_ . .,.** *,.,
Division 2 DG air start valves*Jc!entified o*ut of -position-:_ .* . *.*I
*.*No maintencln;eperforrne&onDiVi*Sio.rL2
,., * .,. *, ,'": ,; . ' *: . 'I*:.. . .:-'" ' .* \. . . '
*;~
DG.d0d6go.Jiaga/*i,*. ,.*. . *. *. ****.*. ,.i**.J
'\' *.
. ,;.~*,
~- .
.*,~_,.:: ,:r C
,, *~) ,'
.~ * .No degr<?1.deq cond.iti.on.~_.for the o*ivisiorJ 2- DG exist~.d - . -- . . . ,..,. .'. - .- . * :* -
- ' . ' . .' ' '.. . -_. , ' ,:* : ' .*, ' .. '. ' ' ', . ' *.. :? : . . . ' ;--_ .. ' . ' . ' ' ' ' :" '". _* ' . ':
- i. .~ **- - . : - ' .. . ~ ' .. - ' *. -
- ,*,. ' *. ,;;: *. 'Shtft.':M~.nager. has iilgh.~cir._allo~EL.AP does rioi,~ist ' ' '.' , .::
):, f\~o.: .. *
. ':":' ~ ,
, * .. * " "# * ,; "' * ~ - '"* ,. ... ~ * -... ~ ... * ' ~ ... '
' ...:.' . ; '. '***~,~ "* . . / f**,*: ~ ,,~;~~- . . . *., :,,:/..
0
- ~*.1~' _.; ~ *.*.~?;~_Y:_'*:-
. * ** * ...... * ;;...... s,et~n.~~P~tqtJ~n.,
~ --*~' __ ..* * - ~ - - -.. ~ - * - * - * . _ _ _ _ _ _ _ _ * ' ',"_ .** .._' . **:_ , ' _ . ' n " * , -~-*
- _. * . . **-...._*: _* *_._ * *. _ *-*----~--~-~
Entry into ELAP i GI Operators are exhaustively trained on the DGs and Loss of AC Power due to high risk significance
- Five simulator scenarios, 26 exam questions, biennial training in last two years
- Operator JPMs for DGs include resetting trips/lockouts and manually bypassing the air start system to manually start the engine with 100% pass rates administered a total of 50 times in the last two years e ERO is trained on LOOP/FLEX
- ERO drills include simulated loss of power and/or loss of DG
- TSC personnel experienced in plant restoration
- Restoration of power is high priority
- Six CPS Shift Managers were surveyed for four potential ELAP scenarios
- All surveyed Shift Managers stated they would not declare an ELAP during scenarios where action was taken to recover power within the 4-hour SBO coping period
- All Shift Managers stated they would not enter ELAP/FLEX procedures once the DG air start valves are identified out of position
- All Shift Managers surveyed stated they would pre-stage FLEX equipment to improve plant risk
- 28 SROs from other stations (including non-Exelon) were given CPS procedures and scenarios that recreated the postulated scenario
- All SROs stated that they rernain in the LOOP procedure and NOT enter ELAP No ,ELAP entry conditions 18 Exelon Generation
Recovery Pathway #1: Division 2 DG Restorat,ion 0 Time validation for a CPS EO to walkdown and identify the out of position air start valves using only system knowledge was 11 minutes
., Time validation for a CPS EO to identify and correct the out of position air start valves per procedure was 29 minutes
- DG full lineup completed within 40 minutes and in service within 50 minutes 0
JPM performed by non-CPS EOs to identify out of position air start valves
- All six EOs identified closed air start valves using procedure within 32 minutes
- DG full lineup completed within 37 minutes e Multiple operators, engineers, and technicians would respond, improving DG recovery time
* . * ** * * :.: *.*. ~: ~ *~ ~- . ,.Division 2**0G* wil*I be recovered in < .1 h~ur * :*.: ~*
* * .l: " + * * .. " ~ ** ,.
19 _.,.,, Exelon Generation
Rule-Based Operator Response to Division 2 DG Failure to Start Knowledge/ Training-Based Response Procedure/ Rule-Based Response DG is recovered. EOs are trained to check the air start A supervisor and additional EOs arrive Air start va Ives a re system after any DG start. The EO is also to support with the procedure in hand. restored by procedure. cued by the alarm card. The out of position air start valves are The Div 2 DG starts The out of position air start valves will be identified by procedure. and restores power. identified during this walkdown. Multiple means to identify out of position air start valves 20 Exelon Generation~
Operator Response to Division 2 DG Failure to Start (Rule-Based) 21
Operator Alarm Response (Rule-Based) I FAILURE TO START I TITLE: FAILURE TO START 5285-3D I DEVICE NAME SETPOINT INDICATION
< 12 5 rpm LOCKOUT RELAY TRIPPED Overcrank and amber light ON K4 Relay > 10 sec after start Dedicated EO requests AUTO ACT I ONS a copy of the DG Loc kout relay trips.
procedures from the Control Room OPERATOR ACTIONS Verify DG lB is ready to start per CPS 3506.01, iesel Generator And Support Systems (DG).
- 2. If the 4160V Bus l Bl is deenergized after DG l B fai ure t o start, refer t o CPS 3501.01, High Voltage Auxiliary Power System to reenergize the bus.
- 3. If required, proceed to CPS 42 00 . 01, Loss Of AC Power.
22 Exelon Generation
Operator Alarm Response (Rule-Based) Opening of the air start valves is procedurally governed
- 2. 0 Placing DG l B in Standby CPS 3506.01P002 On Page 6 of DG 2.2 Starting Air System operating procedure
- 6. Open and lock open the following Air Starting System Air Receiver outlet Valves :
- 1) 1DG160, Air Receiver A Outlet. D
- 2) 1DG161 , Air Receiver B Outlet D Restoration of DC control power following load shed is procedurally governed and does not complicate DG recovery 4.2.4 Re-Energizing 4160V Bus 1A1 (1B1) [lCl] Using DG 1A(1B) [lC ]
4 . (Local) For appli cable Bus 1A1(1B1) re- energization: Load shed circuits Veri f y Ckt J 13( 14) [DG 1A(1B) control] & Ckt 32 (RHR are recovered per control) on DC MCC 1A(1B) [1DC13(14)E] are re- energi zed if Loss of AC Power turned of f by CPS 4200 . 01C002, DC Load Shedding Duri ng A SBO. procedure DG recovered completely by procedures 23 Exelon Generation~
Operator Response to Division 2 DG Failure to Start (Knowledge-Based) I FAILURE TO START I TITLE: FAILURE TO START 5285- 3D I I DEVICE NAME SETPOINT INDICATION
< 25 rpm LOCKOUT RELAY TRIPPED K4 overcrank and amber ight ON Relay > 10 sec after start POSSIBLE CAUSE Starting air receiver pressure is
~ - - - - - - - - - 225-250 psig and did not lower as (D Low starting air pressure
- expected following DG start signal
- 2. Lockout relay not reset
- 3. Overspeed trip handle not reset
- 4. Safety shutdown circuits not reset
- 5. Engine maintenance switch in LOCKOUT position 24 Exelon Generation~
Operator Validates DG Starting Air Parameters Division 2 DG Local Air Start Pressure Division 2 DG Air Receiver Pressure Located on gauge board, as found during the event Tech Spec LCO 3.8.3 Required to log on operator rounds Normal pressure Not on operator rounds prior to event is 225-250 psig EO identifies closed air start valves based on alarms and local indications 25 Exelon Generation~
Operator Response to Division 2 DG Failure to Start This flow path was most recently trained in 2017 Air start path can be easily traced back to the receivers EO JPM to start the DG by overriding the air start system solenoids/Ii neu p; 100% pass rate across 27 Operators in 2017 26
Operator Validates Air Start System Did Not Actuate Through Equipment Checks If the DG received starting air, an oil spray/mist would be visible below the exhaust of the six air start motors 27 Exelon Generation~
Operator Response to Division 2 DG Failure to Start Walking down the air start system is trained and performed with the monthly DG runs CPS 9080 . 02 8 .2 DG lB Operabi1it y (cont ' d) 8 . 2.3 Start Diese Generator lB (cont'd )
- 7) Start DG B with DG lB contro sw ' tch .
8 .2 .4 Verify the following:
- 6. (Local) Verify that an oil mist was exhausted from OR oi residue exists in the exhaust port of al--DG air star motors :
Ca n be ~nd ' c a ted by oi on t he e ng
- ne n ex ~ o t he a ir st rt exha ust par .
EOs trained to check air start system response after DG start 28 Exelon Generation~
Operator Identifies Out Of Position Air Start Valves Division 2 DG air start valve in the Left over tie wraps from clearance order normal "Locked Open" position tags as found on 5/17/18 "Tags Plus" straps left on air start valves 29 Exelon Generation
Operator Response to Division 2 DG Failure to Start 30
~, Exelon Generation~
I
- -- - --- - -- *----- --- ---- - --- - - --- --** ------ - - -- --- *----***- -- -- ---- --- ---- --~------ ------- ---------------*- ---,-----*-----~------------~-------------'i
DG Restoration Summary 0 identification of the out of position air start valves will occur in either knowledge or rule-based space " Air start valves are time validated to be identified by knowledge in 11 minutes and procedure in 29 minutes
- DG recovery is simple task (open air start valves) using regularly executed DG lineup procedure
" Identification of closed air start valves and no visible damage provides Shift Manager High Assurance of Division 2 power recovery
- An ELAP will not be declared
- OCC/ERO technical support and large nurnber of resources
* **. * *: , We h-ad knowledge, lime, and resources to restore Division 2 DG.
31 Exelon Generation
Impact of Actual Response: Div 2 DG Recovery Exelon's DG HEP NRC's DG HEP 0.005 0.2 (99.5% success) (80% success) 0 Realistic modeling of Division? DG recovery, by itself, leads to GREEN significance
- NRC's sensitivity case #3 (using Exelon's HEP) shows Green SPAR-H HEP Impact on PSF NRC Diagnosis Setting Exelon Position Reduction Finding Factor Expansive Available Time Nominal (required time <1 hr) only need 2 hrs, but -50 1 hr 24 hrs available Experience/Training Low Nominal -10 32
__.,.,. Exelon Generation - . -- - -- -*~----- **-*-*---* ------- --*~---~----**-*-- -------------------*--*-------------- --------------- ----*--*----- --
Minimum Shift Staffing* Control Room Team ShiftJv'lanager. (SRO)
***.;-{,-'
"'
- C 2 Senior Reactor:Operators 3 Reactor*
.** Operator~
,.\ ; x;~:~~, .*J* -.-:** -.~" ev*.*. :*_*':.fo:;_'f::W .. M\' ~,,,,.~,. ;,'<>.:,.{. =.x~o0,-~"~ - .>.--<_;4~.,;,~*'~--." *, x~'. _
., / Dedicated Qp Duty
. S~curity Forci;:iviembers ,
"' ~~l{=<~;"; : , .* c-';~.?;' ':* ,,' <>* * ,':
6 ~quipment Operators t 1 IM/EM ERO 2 RP Technicians .:chemistry' t Jechnician. 33
Outage Response Staffing 0 137 - Minimum craft staffing on any shift during the affected window of C1R18 ttttttttt Control Room Team tt tttttttt ttttttttt ttt tttttttt ttttttttt 27 Equipment Operators 6 Senior Reactor Operators 5 Reactor Operators 16 Electricians tttttttttt .......... . tttt 4 Chemistry Technicians
.......... ' ******,*,*,*,*,* tttttt
!!!! ttttttttttt ttttt ttttttttttt 44 Instrument Maintenance 11 Radiation Protection Technicians Technicians 34
- -- - - -- --- - - - - *---- -- --------- ----- - --- --- - -- -- - - - -- ----- --- --- --- -- ----------- - - -- ------------ --------- - - - - - - - - - - * -~
Event Recovery Timeline Activities in Series Start 2 hours 4 hours 6 hours 8 hours 10 hours 12 hours Restore Div 2 DG to Service (50 min) ~ Complete DC Load Shed (1 hour) =)+ Commence FLEX Pre-Staging (1 hour) L,)+ ERO Is Staffed (Alert) (1 hour) [)+
~
Complete Div 3 to Div 2 X-Tie (1.5 hours) End of SBO. Commence FLEX (4 hours) ~~ r -') FLEX is ready for RPV injection (5 hours*) *>+ RCS Boilin_g Be,gins (4 hours) Shutdown Coolin_g Isolated within 6 hours
) ~~
~~
- ~
Time to TAF (No Operator Actions) (10.8 hours) I I I I
, )+
Time to TAF (SDC isolated or RPV pressure controlled low with Batteries) (-24 hours) "' 5 hours is the worst case for FLEX RPV injection and 8 hours is the worst case FLEX heat removal and suppression pool makeup. RPV injection commences before TAF in all cases.
- 1 hour subtracted from FLEX times because they overlap with the first hour of SBO actions.
Substantial time available for mitigation actions even if performed in series 35 Exelon Generation
Recovery Pathway #2: Cross-Tie Div 3 DG to Div 2 Bus - Bus cross-tie completion validated to complete in 1.5 hours
- Open one in-plant disconnect - Open four relay test switches - Remove one relay control power fuse - Control Room performs breaker alignments - Tools pre-staged in operations locked cages and all manipulations in general plant areas - Switchgear breaker and disconnect training occurs every two years - Four page procedure with pictures, locations, and diagrams simplify execution At 1AP09EH, 4160V Bus 161 DG1B Feed 1DG01KB, remove cover and open the following test switch:
1.2.1 Lock open 1APEf4, ET4 Disconnect Switch, CB 737' S.5-129 outside laundry area. (Key #38-WEC Office) {Figure 1) 1) Test switch 4 (fourth from left, bottom) on relay 227X2-21B1-2 {Figure 4) Figure 1 Control Building 737' @ Operating handles for ET4 or ET14. Handles are stored In the electrical equipment locker located In OPS cage on 762' DG (Hl orGMaster Key required for cage access). 36 Exelon Generation
Cross-Tie Div 3 DG to Div 2 Bus During SBO 345k~ chyard ~ ~ RAT-B XFMR Unplanned Out of Div 1 DG service Div 2 DG System Outage Window Division 1 138 k~ chyard - - AC Distribution X AC Distribution 0 AC Distribution 0 Diesel Generator X Diesel Generator X Diesel Generator 0 ERAT XFMR RHR-A/ SOC X RHR-B / SOC 0 HPCS X LPCS X RHR-C 0 DC Batteries 0 DC Batteries 0 DC Batteries 0 37 Exelon Generation
Impact of Actual Response: Div 3 to Div 2 Cross-Tie Exelon's Cross-Tie HEP NRC's Cross-Tie HEP 0.096 0.27 (90.4% success) (73% success) SPAR-H HEP Impact on PSF NRCAction Setting Exelon Position Reduction Finding Factor Available Time Nominal Extra (required time -1.5 hr) (13 hours) (24 hours) Experience/Training Low Nominal
-7 Ergonomics Poor Nominal Complexity High Moderate 38 Exelon Generation~
Recovery Pathway #3: FLEX Implementation and Timeline Extended Loss of AC Power / Loiss of Ultimate Heat Sink ENT Y CONDMON STAnON BLACKOUT
- ENTER 4200.01 Loss of AC Power, Section, 4.4 Station Blackout Do NOT continue in this procedure until directed by 4200.01.
FLEX equipment pre-staged in parallel until implementation required 39 Exelon Generation~
FLEX Implementation and Timeline 0 By 2 hours: Briefs complete, tean1s ready to dispatch 0 By 4 hours: Pre-staging cornplete, hoses and cables run to location, FLEX generator running in standby; plant realignment occurs when directed by Control Roon1 Supervisor
- C) By 6 l1ours: Battery charger in service powering Division 2 batteries, low *pressure RPV makeup is available C, By 8 hours: Decay heat ren1oval and suppression pool rnakeup available e Minimun1 Personnel: 6 Operators, 6 Security Force Members (for 3_hours), 2 Radiation Protection Technicians, 1 Chemistry Technician ill Outage Personnel: At least 15 Qualified Operators+ Supervision, Electrical.and Mechanical maintenance dispatched by the ERO to support as necessary 40
*~- Exelon*Generation
FLEX Training and Experience
"' Task specific procedures are located in field FLEX cabinets 0
Procedures are designed to be "Grab and go" and have prerequisite steps built into each section to ensure all required manipulations are completed 0 Most tasks are similar to normal EO tasks . I
)
- Racking breakers !
j
- Starting FLEX generator (similar to TSC generator)
- Routing cable or hoses 0
Trained in accordance with the Systematic Approach to Training
- From NRC Inspection Report Tl-191: "licensee has trained their staff to assure personnel proficiency in the mitigation of beyond DB events"
-
- EOs trained a'nd proficient with FLEX equipment and procedures 41
~- Exelon Generation
~ -*** -- -- _____,._ -------**-*----*- ---- ------*-*-------------------*-----*-*---------*--------*-------------
Impacts of Actual Response: FLEX Alignment Exelon's FLEX HEP NRC's FLEX HEP 0.002 0.25 (99.8% success) (75% success) SPAR-H HEP Impact on PSF NRC Action Setting Exelon Position Reduction Finding Factor Available Time Nominal Extra (required time ~4 hr) (13 hours) (24 hours) Experience/Training Low Nominal
-12 Ergonomics Poor Nominal Complexity High Nominal
.: * *Realistic mo_deling of FLEX deployment, coupled w.ith higher likelihood of offsite power recovery within 24 hours, leads to Green 42
~ Exelon Generation~
RPV Pressure Control 0 SRVs are available for pressure control for > 24 hours
- Division 1 and 2 DC batteries analyzed with > 24 hours capacity with outage loads
- ADS accumulators and backup air bottles fully charged a> Procedure guidance to stabilize pressure in multiple procedures
- Station Blackout, Loss of Shutdown Cooling, EOP-1, FLEX 0
EOP-1 directs holding RPV pressure < 104 psig until shutdown cooling restored
- Time to boil is 4 hours, SRV usage not needed until at least 8 hours
. \/. RPV pressure controlled to allow use.of low pressure injection systems .
43
~- Exelon Generation
Injection
~ Multiple diverse injection systems available after Division 2 AC power restored using proceduralized actions
- Within 1 minute, start Standby Liquid Control pump "B" from Control Room
.. 43 gpm (4000 gallon tank), injects at any pressure, no field actions required
- Within 1 minute, start RHR-8/C water leg purnp from Control Room
- 50 gpm with RPV depressurized, no field actions required
- Manually start RHR-C for Low Pressure Coolant Injection (LPCI)
- Align RHR-8 from shutdown cooling to LPCI -mode
@ Additional injection systems using proceduralized actions
- FLEX pump direct injection from Ultimate Heat Sink
- Suppression Pool Transfer Pump using FLEX generator power
- Fire pump injection (direct to RPV or using hoses) .
* ~
- Any one Path restores Rev level :
4 ' * ~ ' ~
~
44
~- Exelon Generation*)
Impact of Actual Response - Pressure/.lnventory Control Exelon HEP NRC HEP ' SDC Isolation 0.022 Not modeled (98% success) Maintain RPV Pressure (Using Division 1 or 2 Batteries) 0.001 Not modeled (99.9% success) 0 Both actions procedurally directed
- Success of EITHER action extends time to TAF to about 24 hours
- Increases Available Time for Diagnosis and Action to restore onsite equipment
- Increases likelihood of offsite power recovery 0
Division 1 and 2 batteries available for RPV pressure control (SRVs) for ?4 hours 0 RPV pressure control enhances ability for low or high pressure injection sources
. Reali.stic:,model~ng of loss ofshutqown. cooling actions.and RPV pressure control, coupled with multipl.e sources of irdection, leads to Green 45
~ Exelon Generation
Recovery and Mitigation Actions Summary 0 Identification of out of position air start valves will occur 0 DG recovery is simple task (open air start valves) 0 Shift Manager has High Assurance of Division 2 power recovery © Activities to restore power taken in parallel but controlled to minimize conflicts 0 Other defense-in-depth actions provide additional success paths within the available time
.~ . ~ "
AC power and injection recovered quickly and successfully 46
~- Exelon Generation
Clinton Power Station Regulatory Conference Risk Significance Gene Kelly Sr. Manager, Risk Management Exelon Generation
Risk Assessment for Safety Significance* For White significance, NRC must conclude the SBO condition would not be successfully mitigated because:
- Division 2 DG not recovered within 1 hour and
- ELAP declared at 1 hour and
- Shutdown cooling valve not isolated and
- RPV pressure not controlled and
- Division 3 to Division 2 AC power cross-tie procedurally con1plex and
- FLEX strategy inadequate and not sufficiently trained White significance not based on realisti9 or best available information 48
,. - Exelon Generation
Clinton Power Station Regulatory Conference Conclusion Ted Stoner Site Vice President
.MM+/-
5
/ Exelon Generation0
Conclusion c We had the knowledge, time, and resources to restore AC power 0 NRC policy and guidance dictate risk evaluations to be realistic and based on the best available inforrnation 0 Best available information includes:
- Reflecting a realistic response to the event
- Recognizing extensive operator training and experience
- Appropriately crediting FLEX 0
Using the best available information as presented today and applying the Commission's guiding policies and principles on risk results in: 50
~ Exelon Generation
- -*- -* ---- ..... - - ... ----*-* *---------- ---- -- ......... -*---------------- *------------- - --*-----------..--- ..________________________ __ - - - - - - - - - _________________ __j}}