ML20149F491

Summary of 940712 Meeting W/Util at NRC Office in Rockville,Md to Discuss Results of Control Rod Drop Testing & Subsequent Control Rod Drive Mechanism Testing During Week of 940601

ML20149F491
Person / Time
Site:	Three Mile Island
Issue date:	08/03/1994
From:	Hernan R Office of Nuclear Reactor Regulation
To:	Office of Nuclear Reactor Regulation
References
TAC-M89494, NUDOCS 9408100311
Download: ML20149F491 (15)

Text

.

Mkd h

[ , g ?g UNITED STATES

< E NUCLEAR REGULATORY COMMISSION 3' 4E WASHINGTON, D.C. 205S5 0001

/ August 3, 1994 Docket No. 50-289 LICENSEE: GPU Nuclear Corporation FACILITY: Three Mile Island Nuclear Station, Unit 1 (TMI-1)

SUMMARY

OF JULY 12, 1994, MEETING WITH GPU NUCLEAR CORPORATION REGARDING CONTROL R0D DROP TIME ISSUES AT THREE MILE ISLAND NUCLEAR STATION, UNIT 1 (TMI-1)(TAC N0. M89494)

On Tuesday, July 12, 1994, a public meeting was held at the U.S. Nuclear Regulatory Commission (NRC) offices located at One White Flint North, Rockville, Maryland with GPU Nuclear Corporation (GPUN), the licensee for TMI-1. The purpose of the meeting was to discuss results of the control rod drop testing and subsequent control rod drive mechanism (CRDM) testing during the week of June 1, 1994. Enclosure 1 is the list of participants at the meeting. Enclosure 2 is a copy of the handouts used during the meeting.

The first time that control rod drop times exceeded the Technical Specification (TS) limit of 1.66 seconds was October 1993, at the conclusion of the 10R refueling outage. At that time three rods exceeded the requirement and were brought back within the TS requirement by additional testing. During a scheduled outage in March 1994, surveillance testing indicated that 12 of 61 rods exceeded the TS requirement. All rods were again brought below the TS requirement by additional testing. However, following a meeting with GPUN on March 25, 1994, the staff issued a confirmatory action letter (CAL) to GPUN on March 29, 1994, requiring GPUN to establish a program of per, iodic control rod monitoring, development of evaluation criteria, a contingency plan, and a long term plan for corrective action.

THI-l was shut down on June 1, 1994, to conduct rod drop time testing. On that date, three control rods were determined to exceed the time required by the TS. GPUN removed those three CRDMs plus one other for inspection and replacement of the CRDM thermal barriers. Enclosure 2 summarizes the results of the testing and inspections. GPUN confirmed that the root cause of the lengthened control rod drop times is deposition of crud in the thermal barrier of the CRDMs. GPUN restated that the crud buildup has probably been aggravated by operating at a lower reactor coolant system (RCS) pH than normal as a result of higher boric acid concentrations required for the extended-life cores. Corrective action proposed in a March 26, 1994, letter from GPUN, and repeated in the staff's CAL, consists primarily of raising pH and lithium hydroxide levels in the RCS, and exercising control rods through 10% of their total travel on a biweekly basis. GPUN expects that these actions will result in an improvement in rod drop time. The drop times of the refurbished CRDMs were determined to be satisfactory by testing following refurbishment. p GPUN was advised in a meeting on May 3, 1994, that the staff would consider a temporary revision to the TS limit if it could ba justified by GPUN from a ( :

safety standpoint and GPUN was encouraged to submit a TS change request as j

{$ \

( <. p < c ,n \

EsR"188M 328883e9 PDR NBC RE CENTER CDPY P

GPU Nuclear Corporation August 3, 1994 soon as possible so that the request could be noticed in the Federal Reaister.

Subsequently, GPUN submitted Technical Specification Change Request No. 244 on May 20, 1994, to temporarily raise the TS drop time requirement to 2.11 seconds for eight control rods. The licensee's submittal provided analysis that concluded a 3.0 second drop time for all 61 control rods would still provide adequate protection for the core in the event of an accident requiring an automatic reactor trip. The staff concluded during the July 12 meeting, however, that adequate need for a TS change had not been provided and stated that a license amendment would not be forthcoming.

GPUN discussed their plans for the remainder of the current operating cycle and tnetative plansfor additional CRDM refurbishment during the 10R refueling outage in September 1995 (see Enclosure 2). As stated in the March 1994 CAL, GPUN will submit a long-range CRDM plan to the NRC in September 1994.

This summary replaces the summary of the same meeting issued on July 14, 1994.

Original signed Ly:

Ronald W. Hernan, Senior Project Manager Project Directorate 1-4 Division of Reactor Projects - 1/11 Office of Nuclear Reactor Regulation

Enclosures:

1. List of Attendees

2. GPUN meeting handout cc w/ enclosures:

See next page Distribution w/ enclosures 1 & 2: w/ enclosure 1:

Docket File WRussell/FMiraglia MRubin NRC & Local PDRs RZimmerman LPhillips PDI-4 Memo SVarga HRichings RHernan JCalvo MVirgilio JRogge, R1 JStolz RJones OGC EJordan SNorris ACRS (10)

WDean OFFICE LA:PDI-4 PM:PDI-4 ,

A: PQl-A //_

hAME S r RHernan:cn[gkdoY[

DATE $/j/g4 h/,3/g4 [ / /94 / / / /

OFFICIAL RECORD COPY Document Name: G:\HERNAN\7-12-94. sum

1

\

Three Mile Island Nuclear Station, Unit I cc w/ enclosures:

Michael Ross Michele G. Evans O&M Director, TMI-l Senior Resident Inspector (THI-1)

GPU Nuclear Corporation U.S. Nuclear Regulatory Commission Post Office Box 480 Post Office Box 311 Middletown, Pennsylvania 17057 Middletown, Pennsylvania 17057 ,

John Fornicola Regional Administrator, Region I Director, Licensing & Reg. Affairs U.S. Nuclear Regulatory Commission GPU Nuclear Corporation 475 Allendale Road i

~

100 Interpace Parkway King of Prussia, Pennsylvania 19406 Parsippany, New Jersey 07054 Robert B. Borsum Jack S. Wetmore B&W. Nuclear Technologies TMI Licensing Manager Suite 525 GPU Nuclear Corporation 1700 Rockville Pike  ;

Post Office Box 480 Rockville, Maryland 20852 Middletown, Pennsylvania 17057  !

Ernest L. Blake, Jr., Esquire William Dornsife, Acting Director Shaw, Pittman, Potts & Trowbridge Bureau of Radiation Protection 2300 N Street, NW. Pennsylvania Department of ,

Washington, DC 20037 Environmental Resources Post Office Box 2063 .

Chairman Harrisburg, Pennsylvania 17120 .

Board of County Commissioners of Dauphin County Mr. T. Gary Broughton, Vice President ,

and Director - THI-1 Dauphin County Courthouse Harrisburg, Pennsylvania 17120 GPU Nuclear Corporation Post Office Box 480 Chairman Middletown, Pennsylvania 17057 Board of Supervisors of Londonderry Township  !

R.D. #1, Geyers Church Road ,

Middletown, Pennsylvania 17057

-- - --,,._y--.i.

, ENCLOSURE 1 l

l LIST OF ATTENDEES ,

JULY 12, 1994 MEETING WITH GPU NUCLEAR CORPORATION REGARDING CRD RETEST PLAN TITLE AFFILIATION TITLE i Ronald W. Hernan NRC/NRR/PDI-4 Senior Project Manager Larry Phillips NRC/NRR/SRXB Section Leader Howard Richings NRC/NRR/SRXB Senior Reviewer John Stolz NRC/NRR/PDI-4 Project Directorate

Robert Jones NRC/NRR/DSSA Acting Deputy Director, DSSA

]

Lew Miller NRC OEDO Michele Evans NRC TMI SRI Jacque Durr NRC, Region I DRP, Chief, Branch 4 l

Michael Ross GPUN O&M Director, TMI l

'l T. Gary Broughton GPUN VP and TMI Director l

Pat Walsh GPUN Manager, Plant Engineering Charles Hartman GPUN Manager, Electrical Engrg John Link GPUN Nuclear Analysis  !

Jack S. Wetmore GPUN Manager, Licensing W. M. Drendall GPUN Tech Functions B. Connor GPUN Matl. Engrg., Parsippany Robert Borsum B&W Nuc. Technology Manager Stan Maingi Pennsylvania BRP L

O Enclosure 2  ;

J GPUN-NRC MEETING ACENDA JULY 12, 1994 CONTROL ROD DROP TIMES I. CONTROL ROD DROP TIME TESTING ~ JUNE 1,1994 RESULTS ,

l II. RESULTS OF THE FIELD INSPECTION OF THE FOUR CRDMS  :

AND REMOVED THERMAL BARRIERS o

.a .

l III. PLANS "

l A. REMAINDER OF CYCLE 10 l B. LONGER TERM PLANS

e. . ar ..

IV. DISCUSSION 0F TSCR FOR INCREASED ALLOWED DROP TIME

+- *;*:*'

l l

l

SUMMARY

OF JUNE 1, 1994 DROP TIME TESTING TESTED ALL 61 RODS .;

... . . . i THREE RODS EXCEEDED TECH SPECS AT L-14, GROUP 1, ROD 3 (2.07 SEC)

AT M-9, GROUP 4, ROD 5 (2.0 HSE.Cb ..

.F  : - i'. ; -;-

AT P-8, GROUP 6, ROD 5,"T2.20 SEC)).c; l

i

As Found Time for 49 ' Good' Rods 1.60

~

9 e

c y1.50 s

4 a>

.E H

n '

o w

1.40 A

1.2L63 a; -

~~ _ 1,237 43 0 co k .. < ,-

1.2o5 '

< 1.30 -

/

L.251 1.152 1.151 1.15f

-di

_,,________ap-_______3,____

6R 7R 8R 9R 10R 10 U2 10 P3

Group Average Drop Times - As Found Gp1 9 1.80 -

Gn2 ,

- . 6 _.- ,

Gp3 '

p' ,'

/

~~-O-- - -

n \ ,,

N Gg4 '

/ / ' ~s i

S 1.60 -

\ 's G G /. ,'

~3~5 ~

. h -

\ ',

G6 E

" /

2d)6

/

m - N,.

- , ~

/ / 9 F

u Gp7 -

. /

s I.40 -

\

_ / '5'F/ / -

'fy d> / ,-, .,

+>

..e - - - -n

o. ------- e >' -

-s ' AL P.

u-~-

mv

^

f ,

T}

<~

?

ny. - . .

- L3 -n

~

1.20 We b

e, e

e 6R 7R 8R 9R^ 10 R 10 U2 10 P3

l l

THERMAL BARRIER REPLACEMENT EFFECT ON DROP TIME t

GROUP - TIME TIME TIME NO. OF AS LEFT ROD 10R MARCH JUNE STUCK TIME COR LOC (SEC) (SEC) (SEC) BALLS (SEC)

GP 3 Ro 6 1.72 2.31 l'.'41 4~ l'.328 M3 GP 1 Ro 3 1.83 2.53 2.07 3* 1.312 L 14 GP 4 Ro 5 1.81 2.49 2.01 ""

4 '

1.320

_M 9 j GP 6 Ro 5 .l.43 2.42 2 .20. ,, . 9,33 < . 1.296 i P8 1

• THE FOURTH BALL WAS INITIALLY STUCK BUT. UNSEATED WITH A i FORCE OF APPROXIMATELY ONE POUND.

d

l CHEMISTRY CONTROL DURING JUNE SHUTDOWN AND RESTART l

e PLACED RCS ON CLEANUP TO REDUCE " CRUD" LEVELS TO LESS THAN 0.1 PPM AS AN ADDITIONAL EFFORT PRIOR TO FILLING AND VCNTING CRDMs TO REDUCE PARTICULATE CRUD. I i

1 e INSURED FILL WATER CONTAINED'<0.1 PPM " CRUD" PRIOR TO ADDING TO RCS." THIS CONTINUED A NORMAL .

EFFORT TO REDUCE PARTICULATE CRUD.

l 1

e INCREASED LITHIUM CONCENTRATION TO APPROX. 3.6 PPM PRIOR TO FILL OF RCS AND MAINTAINED LITHIUM HIGH (APPROX; 2.4 PPM)nTHROUGHOUT-THE SUBSEQUENT

. VENTING AND HEATUP.- 1 m +

1 l

o . .

l e DECREASED LITHIUM'SLIGHTLY AS-WE DE80 RATED TO GO ,

CRITICAL-AND PROCEEDED TO 100% POWER OPERATION.

MAINTAINED LITHIUM TO MAINTAIN HOT PH OF 15.9 i

l l

. I i

l

s-_.- _. -- -a,. .ua u- = -- ,=- -.u,- -~ e.- > x-- - - -.-~ -.-

+=

0 4

Y CONCLUSIONS PHYSICAL EVIDENCE OBTAINED DURING INSPECTION i SUPPORTS OUR UNDERSTANDING OF THE CAUSE OF THE SLOW ROD DROP TIMES TO BE CRUD IN THE THERMAL BARRIER CHECK VALVES AND BUSHINGS.

IMPROVEMENT FOUND IN THE AS FOUND DROP TIMES DEMONSTRATES THAT OUR CORRECTIVE ACTIONS WERE EFFECTIVE.

i t

4

-._ _ _ __ _ _ _ __ __ _ . . -- - _ - --- - , .. - . . . _ . . . _ _ , , . . . - s._-. - , ,_, , , , r- , _y- , -----

1 Nuclear TMI CHEMISTRY CONTROL FOR REMAINDER OF CYCLE 10 LITHlUM CONCEN.TRATION AS A RSCTION & BORON CONCENTRATION 4

3.5 N \ .

4 Current f3 3, m - x\ s_ '

M N , ,

, W40% %%WN/4 x s

\ Y -

3 i.,

6 \ s b\

\

i x ~ 3k N \  %

0 1000 1400 i 1230 1000 800 000 400 330 0 1800 1300 190 0 900 700 500 300 10 0 N ppm Current Data:

Boron = 1270 ppm Lithium = 2.2 ppm pH - 6.94

l $

PLANS FOR THE REMAINDER OF CYCLE 10 MAINTAIN LITHIUM /PH CONTROLS.

CONTINUE BI-WEEKLY ENHANCED ROD EXERCISING TO MAINTAIN CLEARANCES BETWEEN THE LEAD SCREW AND THERMAL BARRIER BUSHING.

MONITOR DROP TIMES IN THE EVENT OF A REACTOR TRIP PERFORM DROP TIME TESTING AT THE NEXT UNPLANNED SHUTDOWN.

PERFORM DROP TIME TESTING PRIOR TO ENTRY INTO 11R REFINE OUTAGE PLANS. .

LONGER TERM PLANS e

LONG TERM PLANS ARE INTENDED TO RETURN ALL CRDM'S TO A CONDITION THAT PROVIDES ASSURANCE THAT CONTINUED OPERATION IS WITHIN EQUIPMENT DESIGN.

e BWOG WORK IN PROGRESS e

ALTERNATE DESIGNS AND CHEMICAL CLEANING OPTIONS WITH A REPORT EXPECTED IN AUGUST.

i l

o GPUN WORK / PLANS e SUBMIT A LONG TERM PLAN IN SEPTEMBER 1994.

e PREPARED TO REPLACE 12 THERMAL BARRIERS IN 11R BASED ON o ROD DROP TIME HISTORY 1

e GASKET LEAKAGE AND PREVIOUS GASKET-WORK e ALTERNATE WORK MAY INCLUDE CHEMICAL CLEANING INSTEAD OF BARRIER REPLACEMENT. '

e OUTAGE PLAN MAY BE MODIFIED BY PRE-0UTAGE DROP l TESTING. l e

FUTURE REPLACEMENTS / REPAIRS WILL BE DETERMINED AFTER 11R.

TECH SPEC CHANGE REQUEST 244 e SUBMITTED MAY 20, 1994 e FR NOTICE COMMENT PERIOD EXPIRES JULY 13, 1994 i e WOULD INCREASE ALLOWED DROP TIME FOR 12 SELECTED RODS FROM 1.66 SECONDS TO 2.11 SECONDS e SAFETY ANALYSIS PERFORMED FOR ALL 61 RODS AT 3.0 SECONDS (WITH REDUCED OVERPOWER SETPOINT AT LOW POWER LEVELS) e REASON FOR REQUEST l

e POTENTIAL THAT SOME RODS COULD EXCEED CURRENT  ;

TECH. SPEC. LIMIT BEFORE END OF CYCLE

\

o LICENSE SHOULD REFLECT THIS SITUATION AS AN ANALYZED CONDITION TO ALLEVIATE FUTURE TECH.

SPEC. VIOLATIONS l l

l l

t j