05000318/LER-1980-034-01, /01T-0:on 800727,while Operating at 100% Power for 4,days Unit Exceeded Tech Specs by 8 Mwt.Caused by Leak in Steam Generator Blowdown Recovery Heat Exchanger 21 Which Resulted in Calorimetric Power Calculation Error

/01T-0:on 800727,while Operating at 100% Power for 4,days Unit Exceeded Tech Specs by 8 Mwt.Caused by Leak in Steam Generator Blowdown Recovery Heat Exchanger 21 Which Resulted in Calorimetric Power Calculation Error

ML19331C492
Person / Time
Site:	Calvert Cliffs
Issue date:	08/08/1980
From:	Davis S BALTIMORE GAS & ELECTRIC CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
Shared Package
ML19331C490	List: 05000318/LER-1980-034, Forwards LER 80-034/01T-0 05000318/LER-1980-034-01, /01T-0:on 800727,while Operating at 100% Power for 4,days Unit Exceeded Tech Specs by 8 Mwt.Caused by Leak in Steam Generator Blowdown Recovery Heat Exchanger 21 Which Resulted in Calorimetric Power Calculation Error
References
LER-80-034-01T-01, LER-80-34-1T-1, NUDOCS 8008180506
Download: ML19331C492 (2)

LER-1980-034, /01T-0:on 800727,while Operating at 100% Power for 4,days Unit Exceeded Tech Specs by 8 Mwt.Caused by Leak in Steam Generator Blowdown Recovery Heat Exchanger 21 Which Resulted in Calorimetric Power Calculation Error

Event date:
Report date:
3181980034R01 - NRC Website

text

f FORM 366 1

LICENSEE EVENT REPORT wNTGOL SLOCs(: l l

l l

l l

l (PLEASE PRINT OR TYPE ALL CECUCED INFC'.MATi"N1 1

6 l M i o i c l c lN l 2 l@l 0101 -l 0l 0l 0l 010l -! 0l Ol@l 4I il 1111 lj@l l

l@

o i 7

8 9 tickNSEE CODE 14 15 LsCENSE Nww8tR 25 26 LICENSE TV,( Js*

$7 CAT bd con 4 10151 l'"C dl0151010101311 18 l@l01712 171810 l@l 018101818l Ol@

8 60 61 OOCK ET NUVS E R 68 69 EVENT DATE 74 75 REPORT D ATE 80 EVENT DESCRIPTION AND pro 8ABLE CONSEQUENCES h Lo_L ! 10n 7/27/80, it was confirmed that Unit 2 exceeded 2700 MWth (T.S.1.3) by 8 MWth i

10131 Iwhile the unit was operating at 100% power for approximately four days due to l

1o 91 l an undetected leak in #21 steam generator blowdown recovery heat exchanger l

1 o # si l(SG80RHX) which resulted in a nonconservative error in computer calorimetric l

o 6 l calculation power. The leak was isolated and correct blowdown flow was l

iTTT) I entered into the calculation at 1315 on 7/27/80.

LER 80-35 (U-2) describes i

I 1 o Ie I LLsimilar event.

80 E

CC"D E su C E CCVPON ENT COCE SLS CE S

DE FoTTl I z 1 z l@ LxJ@ l zi@ l 21 zl zi z l z i z i@ i zl@ Lz_j @

7 8

9 to 11 12 13 18 is 20 SE QUE NTI A L CCCURRENCE REPCRT R E vistDN t ER no EVENTVEAR R(PORT NO.

CODE TYPE NO.

@,afg 18 10 I l-l 1013141 M

10111 1 Tl 1---J LOJ 21 22 23 24 26 27 28 29 30 31 32 vhm

• OUR$

$8 i O

FOR B-5 LE MANLFAC RER TAE N ACT ON ON PL NT [G_j@[_zj@

[Z_j@

[_z_j@

l 010l 010l

[,YJ @

[ N_j@

l z l@

l X l 9 l 9 l 9 Ig 33 34 35 36 31 40 41 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h 1:101IThe cauw was dua to tube failure in di21 SGBDRHX which is coo' led by condensate.

I L'_L'J l This caused an erroneously high blowdown flow rate which resulted in an error I

l in the nonconservative direction for the calod metric power calculation.

A I

i,12i L'_L3_J l weekly preventative maintenance channel check will be imolemented to verify l

I

, L'_LJ l blowdown flow rate.

so fA

% POWE R OTHER STATUS DISCO RV O'SCOVERY DESCR'PTION L2J@ l of s10181 NA I

L sJ@l special Test I

li s

'5

.!Tivm CCETENT TOC,T.ONC,REuisE@

.oOuNT C, CTiv,Tv @ l r.E u.sEo 0,RE u.sE NA l

NA l

L1]@ [Z_j@l i 6

,ERsONNELnPCsSEs cEsCR,, TION @

~uu.ER Tv,E l

10101 Ol@LZ_J@l NA li 2

,ERsONNEL,NJEs t'

cEsCR:, TION @ NA l

Nev.E R l0101Ol@l i a 80 7

8 9 11 12 T E CESCR 8T ON I

LZj@l NA i 9 7

8 9 10 tSSUE @ DESCRIPTION [yj l

NA I

IIIIIIIIIII!II 2 o

' s d (f8 i s gg......,

s. M. Davis (301)269-4742

, oN E.

LER NO.

80-34/1T DOCKET NO.

50-318 EVENT DATE 07/27/80 ',

REPORT DATE 08/08/80 ATTACHMENT EVENTDESCRIPTIONANDPRO3ABLECONShuENCES:

On July 27, 1980, it was confimed that Unit 2 had exceeded rated thermal power of 2700 K4th (T.S.1.3) for approximately four (4) days when the unit was operating at 100% power.

This event was caused by an undetected leak in #21 steam generator blowdown recovery heat exchanger which resulted in an erroneous input to the plant computer's calorimetric power calculation.

On July 26, 1980, !21 steam generator blowdown recovery heat exchanger which is cooled by condensate water was discovered to have an approximately 230 gpm leak from the condensate side to the blowdcwn recovery side. As the -

leak increased in magnitude, the Operator closed the throttle valve to maintain the required indicated blowdown flow rate.

This action resulted in an ermr in the nonconservative direction between actual blowdown flow rate and indicated blowdown flow rate.

It has been estimated by conducting a hand calculated heat balance and confirmed by an actual test that the leak caused an error of approximately 8 Kith in calorimetric power.

At 1315 on July 27, 1980, the heat exchanger was isolated and placed out of service after it was confimed to have failed tubes.

After the heat exchanger was placed out of service and proper response of the blowdown flow rate meter was verified, the correct blowdown flow rate was entered into the computer calorimetric calculation.

An investigation was conducted in an attempt to verify the actual inception date of the leak so that a best estimate could be made as to the actual length of time the unit exceeded 2700 !s'th.

Two parameters were studied.

First a comparison of calorimetric power to incore instrument power was made, however, the results were inconclusive.

The second parameter studied was steam generator chemistry.

This data showed that blowdown became ineffective on 7/22/80.

Therefore, it.was concluded that the # 21 steam generator blowdown recovery heat exchanger tubes failed on that date.

Af ter reviewing the unit's power history and assuming that the Icak started on 7/22/80, it has been concluded that the unit exceeded power for91 hours.

$n cssessment of the significance of the overpower condition on tne Safety nnalysis concluded tnat tne overpower condition was more than offset, since local peaking factors (F t and F t) remained at least 8% below their Technical x

Specification limit duri"ng the ev3nt.

Therefore, an adequate margin of safety r-r.a i ned.

CAUSE DESCRIPTION AND CORRECTIVE ACTIONS:

The cause of this event was due to tube failure in ! 21 steam generator blowdown heat exchanger which resulted in an erroneous input to the plant co.rputer calcrimetric power calculation.

Corrective action to prevent recurrence will be to implement a weekly preventative maintenance functicnal check to verify proper blowdown flow rate.