ML18139A610

LER 80-009/01T-0:on 800718,Westinghouse LOCA ECCS Reanalysis Indicated Error in Fuel Clad Burst Model.Caused by Reduction in Clad Heatup Rate Which Shifts Fuel Clad Burst Curve & Results in Earlier Clad Burst.Limit Will Be Controlled

ML18139A610
Person / Time
Site:	Surry
Issue date:	07/31/1980
From:	WILSON J L VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML18139A609	List: ML18139A608 ML18139A610
References
LER-80-009-01T, LER-80-9-1T, NUDOCS 8008040118
Download: ML18139A610 (3)

Text

CONTROL BL 0 0CK: 1 8 (PLEASE PRINT OR TYPE.L REQUIRED INFORtJ..:.TIONJ o I -I o Io Io Io I O I 0 I O 101 4 1 1 1 1 1 1 11 101 I I G LICENSE NUMBER 2!:> 2G LICENSE. TYPE 30 :S C.:..T :,8 l V I A Is I p I s I 2 101 0 LICENSEE CODE 14 1~

L!:_JG) 1 o I s I o I o I o 1 2 1 s I o 101 o I 7 11 I 8 I s I o l(v I o I 7 I 3 I 1 1 s Io 10 60 61 DOCKET NUMBER 68 69 EVENT DATE 74 7:, REPORT DATE BD EVENT .DESCRIPTION AND F'ROBABLE CONSEQUENCES@

I Westinghouse LOCA-ECCS reanalysis indicates that a residual penalty of O .007 i=-FQ exists 9 from the fuel rod burst model. The error in the fuel clad burst model was rep:rted 11-26-79 in Unit 1 LERNO. 79-032/0lT-0.

As a result, the FQ Limit (T.S.3.12.~.l) must be reduced. This is reportable as per T.S. 6.6.2.a.8.

8 9 6 SYSTEM CODE I RIC I@ 9 10 CAUSE CAUSE CODE SUBCODE COMPONENT CODE Lu@ L!J@ IFjUjEjLjXj x1@ 11 12 13 18 COMP, SUBCODE L:J 19 C SEQUENTIAL OCCURRENCE REPORT r.::;,. LER/RO EVENT YEAR . REPORT NO, CODE TYPE \'..:./N"i;~~~~

Is I 0 1 I I 1° 1° I 9 1 1.....--1 lo l 1! L!J . 21 Xl 23 24 26 27 28 29 30 VALVE SUBCODE w@ 20 31 ?.EVISION NO. w 32 80 ACTION FUTURE EFFECT SHUTDOWN @ ATTACHMENT NPR0-4 TAKEN ACTION ON PLANT METHOD HOURS SUBMITTED FORM .SUB. l..u@L!J@

~(§) L2J 10 10 I Oj 01 l2..J ~ PRIME COMP. SUPPLIER COMPONENT MANUFACTURER 33 34 36 3 7 40 41 42 ~@) I wJ 1 I 2 Io I@ CAUSE DESCRIPTION AND_CORRECTIVE ACTIONS@ 43 0 I The* fuel clad burst error wa~ caused .by :a reduction in clad heatup rate which shifts the }] !fuel clad burst curve and results in earlier clad burst. The FQ.lirnit will be TI _ladrninistratively controlled at 2.18 pending NRC evaluation of the Fuel Clad burst* model 3 jand possible LOCA-ECCS Reanalysis.

4 B 9 FACILITY . ,.;;;.. METHOD OF A <17 BO STATUS %POWER S/ OTHERSTATUS

\:SI 5 l.£J@ IO IO j ~@)!RepTaee\Tient outage j 8 A2flVITY C~~TENT 12 1J 44 DISCOVERY DISCOVERY DESCRIPTION i&. ~@ .... I _N_o_t_i_f_i_c_a_t_i_o_n_f_r_o_m

__ N_s_s_s _________

---

1 ~5 46 80 RELEASED OF RELEASE AMOUNT OF ACTIVITY @ J GJ@) ~@I NA 8 9 . 10 1~1:--------------..J PERSONNEL EXPOSURES 4-4 NUMBER TYPE DESCRIPTION@

NA LOCATION OF RELEASE @ 45 80 NA Q I o I o Io l021W@ I 8 9 11 12 1::3:----------------------------------------~

PERSONNEL INJURIES BO NUMBER DESCRIPTION@

'O I o I o I o I@ 8 9 11 ,;--;2;---------------------------'=---------------------J LOSS OF OR DAMAGE TO FACILITY@

TYPE DESCRIPTION 43 I] t2J@ . NA 60 NA 8 9 10 PUBLICITY r.;,.. 80 0 ~/ J!l,.. ,ssurnr,;:;\

DESCRIPTION~

8 o 4, o , j a J l NJ0:--;;-10

___________

_.:N~A:....._

_________

__j I I 1 ! 1 I i I II I I I~ 68 69 BO NRC I.Ee ONLY (804) 357-3181'..

ru:,ME OF PREPARER J. L. Wilson oun ... ,r.

ATTACHI-IENT 1 *SURRY POWER STATION DOCKET NO: 50-281

• REPORT NO: 80-009 /0lT-0 EVENT DATE: 7-14-80 TITLE OF EVENT : FQ LIMIT RESTRICTION

1. Description of Event: On November 9, 1979, VEPCO was notified of an unreviewed safety question by Westinghouse Electric Corporation.

The unreviewed safety question concerned a potential non-conservative feature of the Westinghouse ECCS large break evaluatio~

model which could affect the peak clad temperature calculated for the tOCA. transient, specificly in the fuel clad burst model. Westinghouse,in evaluating their fuel Clad Burst model,has recommended a conservative, interim limit 'Be 9-pplied--to*

~the. mode.1--pending

• NRG approval of their new Fuel Clad Burst model. Westinghouse analysis (with the interim**

limits) of Surry Unit 1 indicated that sufficient margin existed in the FQ-limit, but for Surry Unit 2, there existed a ,_ residual penalty of O. 007 in Fq based on the present Fq "limit of 2*:.19. ' This event is reportable in accordance wit:h Technical Specification 6.6.2.a.8.

2. Prob ab le Consequences/Status of Redundant Sys terns-: The Westinghouse evaluation revealed that heatup rates could be <25°F/second During the LOCA transient, the fuel clad burst curve establishes the time of clad burst and the post-burst conditions of the c.lad. The fu~l clad burst curve is dependent on the clad heatup rate prior to burst, and a reduction in clad heatup rate causes earlier cla~ burst, Since Surry Unit 2 has not operated since this event was reported, the health and safety of the general public have not been affected.

3. Cause The potential non-conservative feature of the Westinghouse large break ECCS evaluation utilized a model which uses a curve that represents fuel clad burst conditions for clad heatup rates of > 25°F /second .. The* fuel clad burst curve is dependent on the clad heatup rate prior to burst and a redu*ction in heatup rate causes earlier clad burst.' A shift in clad burst time can affect the peak clad temperature (PCT) calculated for the LOCA-transient.

4. Immediate Corrective Actions: Since the current Surry LOCA-ECCS analyses exhibited heatup rates less than 25°F/sec., a specific reanalysis was performed to ascertain the effect on PCT for the Surry Unit 2 analysis.

The Fq limit will be administratively restricted to 2.18 as an interim measure until NRC fuel +9d burst mpdeling co~c~rns_are r~9 o~ye9. ~lJ ijo~ ~hannel factor surveillance will be analyzed based *on this interim li:r.n.t.

5. Scheduled Corrective Action: Once the Fuel Rod Burst model concerns are -resolved-, the model will be evaluated for Surry to determine if LOCA-ECCs analysis and possible Technical Specifications changes will be required.

for present Fq limits.

}.TTACHHENT 2

• e 6. Action Taken to Prevent Recurrence:

No other action will be necessary to prevent recurrence.

7. Generic Implications This event was a Westinghouse identified generic item and was reported under LER No. 79-032/0lT-0 for Surry Unit 1 and 2.