ML20196E317

Retracted RO 80-26 Re B&W Abnormal Transient Operating Guidelines Program Analysis Concerning Steam Generator Tube Rupture.Concerns Addressed in RO 80-26 Never Valid Since Procedure E.06 Ensures That Offsite Dose Limits Met

ML20196E317
Person / Time
Site:	Rancho Seco
Issue date:	02/18/1988
From:	Andognini G SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:	Martin J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V)
References
80-26, GCA-88-088, GCA-88-88, NUDOCS 8803010028
Download: ML20196E317 (4)

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QlEQ SACRAMENTO MUNICIPAL UTILITY DISTRICT C 6201 S Street, P.o Box 15830. Socramento CA 958524830.(916) 452 3211 AN ELECTRIC SYSTEM SERVING THE HEARTIOF CAUFORNIA FEB I 819?8 IC d ! !4 GCA 88-088 U. S. Nuclear Regulatory Comission Attn: J. B. Martin, Regional Administrator Region V Office of Inspection and Enforcement 1450 Maria Lane, Suite 210 Halnut Creek, CA 94596 Docket No. 50-312 Rancho Seco Nuclear Generating Statior' License No. DPR-54 RETRACTION OF REPORTABLE OCCURRENCE 80-26

Dear Hr. Hartin:

The Sacramento Municipal Utility District hereby retracts Reportable Occurrence 80-26. Reportable Occurrence 80-26 was based on the results of B&H's Abnormal Transient Operating Guidelines (ATOG) program analysis for ANO-1 concerning a steam generator tube rupturc-(SGTR). That ATOG analysis determined that the FSAR analysis regarding the calculation of offsite dose followingaSGTR,maynotbe]oundingforallplants.

When B&H's initial ATOG analysis was issued in 1980 it was not an acceptable substitute for an FSAR-type analysis; however, B&W was to provide interim operator guidelines covering a SGTR event for ANO-1. The District comitted to review the new B&H operator guidelines and incorporate them into existing procedures, if applicable.

In July 1985, the ATOG analysis was superseded by the generic Technical Basis Document (TBD). The TBD provides the technical basis *or Pancho Seco's Emergency Operating Procedures (EOP). In the past, operator actions during a SGTR ware not based on offsite doses; however, procedure E.06 "SGTR," Revision 8 now provides specific guidance to ensure that the Technical Specificatioa offsite dose limits are not exceeded. Moreover, the Technical Specification effsite dose limits are a factor of ten below ;he limits specified in the TBD.

The documents which support the adequacy of the E0Ps are outlined in District memorandum NL 88-172, dated February 9 1988. A copy of this memorandum is attached.

980301002a suC21G DR ADOCK O N

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RANCHO SECO NUCLEAR GENERATING STATION O 1444o Twin Cities Road. Herald, CA 95638 9799.(209) 333 2935 Pm t i

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t GCA 88-088 r

, J.B. Martin FE81 s 1983 [

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) Reportable Occurrence 80-26 was based on the results of the ATOG analysis [

program for ANO-1. The ATOG analysis was superseded by the TBD and current .

Rancho Seco E0Ps are based on this TBD. Procedure E.06 lists specific  !

! operating criteria to ensure that the offsite dose limits of Technical

) Specification 3.1.4 are met; therefore, the concerns addressed in Reportable i 3

Occurrence 80-26 were never valid.

i 5 Based on the above, the District requests that Reportable Occurrence 80-26 be

retracted, i

i Please contact me if you have any questions. Members of your staff with i questions requiring additional information or clarification may contact

Mr. Bob Jones at (916) 452-3211, extension 4675. '

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Sincerely,  !

I f a ///w i G. arl Andognt i Chief Executive Officer,  !

Nuclear l Attachment cc: G. Kalman, NRC, Bethesda (w/atch)  !

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A. D'Angelo. NRC, Rancho Seco ( " )

, F. J. Miraglia, NRR, ( "

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SACRAMENTO MUNICIPAL UTILITY DISTRICT l OFFICE MEMORANDUM NL 88-172  ;

B b Croley DATE. February 9j 1989 g foi l

p,,,,,ed by: Bob Jones R,vi,wed by: Dave Schumann febwm app,,,,4 dy: Steve Crunk hLhtd f RETRRCTION OF REPORTABLE OCCURRENCE ~40-26 susJecT:

on May 21, 1980, the District submitted Reportable ,

Occurrence 80-26. This Reportable Occurrence was based on the results of B&W's Abnormal Transient Operating  !

Guidelines (ATOG) program analysis for ANO-1 concerning a steam generator tube rupture (SGTR). That ATOG analysis determined that the FSAR analysis t'or a SGTR may not be ,

bounding for all plants. The Reportable occurrence listed the following factors which may contribute to differences in the analyses i

0  !

1. Recent requirements to maintain 50 F

" subcooling in ths RCS during such an ,

l event and small break guidelines regarding RC pump trip which reduce l plant depressurization capabilities.

regarding periodic f

2. Consideratiens steam ,

steaming of the affected to prevent overfilling- i generator that generator. l

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3. Contaminated steam the released to the auxiliary environment via feedpumps exhaust while the affected l steam generator is in service during a coincidental loss of offsite l power, ,

The District committed to review the new B&W operator  ;

l guidelines and incorporate them into existing procedures, if applicable. Further, the District committed to submit

[

j a revised FSAR upon furthur information and clarification from B&W. .

l In the past, operator actions during a SGTR were not based on of fsite doses. Currently, Emergency Operating  !

E 06 "SGTR" Revision 8 lists specific Procedure (EOP)

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. L DOB CROLEY NL 88-172 j criteria regarding steaming and isolation of the OT3G to ensure that the Technical Specification offsite dose limits are not exceeded.

The requirement to maintain 500 F subcooling in the Reactor Coolant System during a SGTR has been superseded t by the variable subcooling margin (VSM) curve. The VSM  ;

curve allows the reactor to be operated at pressures lower than the original 500 F subcooling margin. I Procedure E.06 requires that the subcooling margin be monitored and maintained continuously throughout the  :

event.

Procedure E.06, Section 11.0 addresses steaming of the Once-through Steam Generators (OTSG) to ensure that j appropriate water level is maintained. Section 15.0 i states that steaming may continue until the calculated offsite exposure reaches 250 mrem whole body or 2.5 rem thyroid.  ;

To mitigate- the offsite dose from contaminated steam released to the environment via the auxiliary feedpump i exhaust, procedure E.06, Section 15.0 requires tnat the ,

affected OTSG be isolated if Auxiliary Feedpump P-318 is inservice using turbine drive. This requirement is not '

applicable if dose calculations indicate that the offsite  ; ~

exposure is less than 250 mrem whole body and 2.5 ra -

! thyroid.

i  !

The original FSAR analysis makes conservative assumptions regarding the size of the break and the amount of i i8 radiation leaking directly to the environment. Current EOPs list specific operating criteria for a SGTR event to ensure that the offsite dose limits of Technical Specification 3.1.4 are met. The offsite dose limits in ,

Technical Specification 3.1.4 are conservatively set at a f factor of ten below the requirement in the Technical i

) Basis Document.  ;

r Based on the above, the concerns addressed in Reportable  !

! Occurrence 80-26 are no longer validt therefore,

! Reportable Occurrence 80-26 should be retracted. l l

l cc: NL Files 1 RIC I I r l

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