ML18127A651

LER 1978-025-00 for St. Lucie Unit 1, on 07/24/78 Concerning an Error in the Analysis for the Cask Drop Accident Which Makes the Technical Specification 3.9.14 Non-Conservative

ML18127A651
Person / Time
Site:	Saint Lucie
Issue date:	08/07/1978
From:	Schmidt A Florida Power & Light Co
To:	O'Reilly J NRC/RGN-II, NRC/IE
References
PRN-LI-78-219 LER 1978-025-00
Download: ML18127A651 (5)

Text

of(<<(o0 REGULATORY XNFORNATION DISTRIBUTION SY TEN<RXDS)DXSTRIBUTION FOR INCOMING NATERIAL 50-335 GRG;SCHMIDT A D DOCDATE: 08/07/78 FL PWR 8(LIGHT DATE RCVD: 08/15/78 REC: OREXLLY J P, NRC DOCTYPE: LETTER NOTARIZED:

NO COPIES RECEIVED

SUBJECT:

LTR 1 ENCL 1 LICENSEE EVENT REPT 50-335/78-25 ON 07/24/78 CONCERNING AN ERROR IN THE ANALYSIS FOR Tl-IE CASK DROP ACCIDENT WHICI.I MAKES TFIE TECH SPEC 3.9.14 NGI4-CONSERVATI VI:.PLANT MANE: ST LUCXE 4I:1+~+cs<sss+u<>'s<

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LTR 45 ENCL 45 SIZE: 3P%%%%%%%%%%.2%%%%%4I%%%%%%%%%8c 0M 0F%0f%%0$TIIE END CONTROL NBR: 782230377 4 g'k a+~//FLORIDA POPOVER 5 LIGHT COMPANY Mr.James P.O'Reilly, Director, Region II Office of Inspection and Enforcement, U.S.Nuclear Regulatory Commission

'30 Peachtree Street, N.M., Suite 1217 Atlanta, Georgia 30303

Dear Mr.O'Reilly:

REPORTABLE OCCURRENCE 335-78-25 ST.LUCIE UNIT 1 DATE OF OCCURRENCE:

JULY 24 1978 August 7, 197g-P RN" L I-78-219m~

I<<X)<..C/l~C/l~n CA CASK DROP ANALYSIS The attached Licensee Event Report is being submitted in accordance with Technical Specification 6.9 to provide prompt notification of the subject occurrence.

Very truly yours, JiP A.D.Schmidt Vice President Power Resour ces MAS/ms Attachment cc: Harold F.Reis, Esquire Director, Office of Inspection and Enforcement (40)Director, Office of Management Information and Program Control (3)782230377 PLOPLF.~.SERVING PFOPI.F 0 NAC FORM 666 P TTI LlCENSEF EVENT REPORT U<<*NUCLEAR AEGULATORY COMMISSION CONTROL BLQCICI I lQI (PLEASE PAINT OR TYPE ALI.A'EQUIREO INFORMATIONI Q.15<<6 LICSNSS TY)<<0 Sl A<<ja C.9 LICcNSK K COOK~4~5 I.ICK NSK NLMef<<4~<<<<PI LIB LIBI1 r 0 Ol-0 01010101-10 It<<4 II XIIIX Q~IQ<<CON'T~OI 1 8 0 2 souAc I X JQB 0 5 0 I 0 l 0 l 3 3 5 OT 0 I 60 61 COCK 8 T NUM 9 6 R EVENTOESCAIPTION ANO PAOBABL-COIYSECUcNCc QIO Because of an error in the anal sis for 7 2 4'7 8 6 0 8 Ol 7I 7 8 QB fy NTOAtf 15 RK)QAT QATK 40 the cask dro accident T.S.3.9.1 4 i s.non-conservati ve.It has been determined that a dro ed cask could impact a larger radius, therefore, a longer decay time is needed before a cask.can be moved into the spent fuel pool cask compartment.

There are no adverse conse uences because of the small amount of fuel in the pool and the high degree of conservatism in the analysis.~Oa 1 8 9 SYSTeu CAUSe CAUSK COMP.VALVS COOK CQOK S'U8CQOK CQMPON KNT COOK suacoof suscQQK~<<<<~PB Qrl~BQ>>~A Q<<<<X X X X I X X Q<<~ZQ<<~Z Qi-9 10 ll 12 12 IS 19~0 Scouf NTIAL OCCUAAKi4CK Rc)OAT RKVISIotl<<

Lca!AO KVKNTYKAA itf PORT HO.COOK HO.Q<<r<<ir<<<<r~7S~~02 5~<<~01~X 21 22~23 24 26 21 8 29 0 3'I 22 ACTION Fut<<JAS cFFKCT SI4UTCOWN At-.ACNMK NT Nr ROM PFAue CQMr.=COMPONK H r TAKcN*I TION Ctl PI.ANT Mf T<<IQO I<<OVAS 22 SUBMITTKO FOA!45ua.SUPPLISR u*NVFACTUAKR LBOLJS LRS>>IS~>>>>S LJS MS<<5 26 3)4l 42 43 44 41 CAUSE DSSCSIIPTION

<<I<<NO CORRECTIVE ACTIONS Q21 0 The cask dro was not anal zed in accordance with FSAR methodolo y, there by leading to a non-conservative basis for T.S.3.9.14.A boundin analy sis has been erformed and will be administrativel a lied in case use o the soent fuel cask is re uired before a ro osed Technical S ecificationl 9 amendment can be submitted.

and a roved b the NRC.1 A ILITY S.A<<VS;I)OWfA OTIIKR5 ATUS DOO LOS~i'S~8 Is 18 12 44 ACTIVITY.CQNTK NT AKLKASKO OF Afl.KASK AM(IVNT~F*CTIVITY QSS~zQ>>~zQS'A 1 8 10 II 44 FKRSONNfL KX)OSUAKS~OII'0 Q<<r~ZQB<<'A 1 I I I'2 13 Pf ASCNNK L IPUL'Ates pZg~o"'8'"0 Q'"'"'".III<<~DQSI NOtif iCatiOri VrOm 7/4 45 gA LOCA'tloN OF<<IKLKASK Q 45 KO 30 30 a 2 II l2 LCSS OF CA OAMAC-0 F*CILITY Q42 TYPf.of>>AlrtloN zQ2 10 rueLICI TY ISSUKO OKSCAIPI.CN LPJ~glQ44 9 10 NAME OP PREPARER PIION6: I'<<I 80 30 NAC USE ONI.Y ee'69 W Reportable Occurrence 335-78-25 Licensee Event Report Pa e Two Additional Event Descri tion During power operation, the Architect/Engineer found an error in the accident analysis for the drop of a spent fuel cask into the spent fuel pool.As a result of the error;Specification 3.9.14 on spent fuel handling is non-conservative.

The analysis was originally performed assuming a single pendu-lum, which gave a drop radius of 133 inches.The FSAR methodology, however, specifies a double pendulum, which gives a drop radius of 248 inches.This means that a dropped cask could impact more, fuel elements, therefore,"fresh" spent fuel must be stored farther from the cask area and/or allowed to decay longer before the cask can be moved into the spent fuel pool.The probable consequences of the occurrence are not signifi cant because fuel was stored in the pool for only 2 months before the error was found, and there is considerable conservatism in the dose rate analysis for the cask drop acci-dent.This was the first occurrence involving a calculational error associated with a spent fuel system.