ML18227D420

Submit Supplemental Information to FPLs Request to Postpone Inspection of Steam Generators

ML18227D420
Person / Time
Site:	Turkey Point
Issue date:	02/09/1978
From:	Robert E. Uhrig Florida Power & Light Co
To:	Lear G Office of Nuclear Reactor Regulation
References
L-78-49
Download: ML18227D420 (8)

Text

REGULATORY INFORMATION DISTRIBUTION SYSTEM (RIDS)

DlSTRIBUTION FOR INCOMING MATERIAL 50-251 REC:

LEAR G

NRC ORG:

UHRIG R E FL PWR 5 LIGHT DOCDATE: 02/09/78 DATE RCVD: 02/16/78 DQCTYPE:

LETTER

'NOTARIZED:

NO COPIES RECEIVED

SUBJECT:

LTR 3 ENCL 3 SUPPLEMENTAL INFO TO APPLICANT"S 01/18/78 REQUEST TQ POSTPONE THE INSPECTION QF THE STEAM GENERATORS AT UNIT 4.

PLANT NAME: TURKEY PT $3 REVIEWER INITIAL:

XJM DISTRIBUTOR INITIAL:

++++++++++++++4++ DISTRIBUTION OF THIS MATERlAL IS AS FOLLOWS GENERAL DISTRIBUTION FQR AFTER ISSUANCE OF OPERATING LICENSE.

(DISTRIBUTION CODE A001)

FOR ACTION:

INTERNAL:

EXTERNAL:

BRANCH CHIEF SCHWENCER44W/7 ENC EG FILE~a /ENCL

/2 ENCL HANAUER+~W/ENCL EISENHUT4 +W/ENCL BAER44W/ENCL GRIMES++M/ENCL J.

MCGOUGH++W/ENCL LPDR S MIAMI~

FL++W/ENCL TICKS< WfENCL NS IC++W/ENCL ACRS CAT 844W/16 ENCL NRC PDR+4W/ENCL OELD>+LTR ONLY CHECKS< WfENCL SHAO+4W/ENCL BUTLER++W/ENCL J COLLINS+>W/ENCL DISTRIBUTION:

LTR 40 ENCL 39 CONTROL NBR:

780480240 SIZE:

1P+2P

/

THE END

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I, mj~%PQ41+M, MIAMI, FL 33101 j~qlpg] 90 yklllz FLORIDAPOWER & LIGHTCOMPANY February 9, 1978 L-78-49 Office of Nuclear Reactor Regulation Attention.:

Mr. George Lear, Chief

= Division of Operating. Reactors, Branch 2

U. S. Nuclear Regulatory Commission Washington, D.C.

20555

Dear Mr. Lear,

Re:

Turkey Point Unit 4 Docket No. 50-251 Request for Amendment to Operating License DPR-41 Additional Information

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~/pe cg qr OII Attached is supplemental information to our request to postpone the inspection of the steam generators at Turkey Point Unit 4.

This request was submitted, January 18, 1978 (L-78-23).

Yours ver

truly, R. E. Uhrig Vice President REU/NLR/lah Attachments cc:

J.

P. O'Reilly, Region II Robert Lowenstein, Esquire 78048Q2gO idol 3/p PEOPLE... SERVING PEOPLE

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e TURKEY POINT UNIT No.

4 REQUEST TO CONTINUE OPERATION BEYOND PERIOD AUTHORIZED BY NRC ORDER Considering the 15% tube hoop strain contour for Turkey Point Unit 4 at 5

EFPM beyond closure (the approximate current status of the plant), within this contour in steam generator B (the worst steam generator) are approximately 175 unplugged tubes.

Reviewing the results of the recent reinspections of Surry 1 and 2 and for con-ditions similar to that of Turkey Point Unit 4 (i.e., the 15%

tube hoop strain contour at 5.5 EFPM), within"these contours were approximately 270 and 260 unplugged tubes prior to these reinspec-

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tions in steam generator C of Surry 1 and steam generator A.of Surry 2 respectively.

These were the worst steam generators for these units and are the steam generators upon which the Surry strain contours were based.

Over the six month operating period 2 leakers in steam generator C of Surry 1 and 1 leaker in steam generator.

A of Surry 2 occurred in the tube lane region.

Assuming consistency of behavior between the Surry units and Turkey Point 4, one would expect in the" order of 2 leakers to have occurred during a similar six month operating period of Turkey Point Unit. 4.

This in fact is very consistent with th'e actual operating history of Turkey Point Unit 4 over the last six months (1 previous leaker in steam generator B and the current.leak in steam generator A).

Thus it appears reasonable to expect that the occurrence of tube restrictions in steam generator B is similar to that of the Surry units.

Considering the occurrence of.540 restricted tubes in 'the tube lane of the above mentioned Surry 1 and 2 steam generators, a total of 10 and 5 such tubes respectively developed over six months. of operation.

Ratioing the occurrence of these

.540 re-stricted tubes in the tube lane region to the total unplugged tubes within the 15% tube hoop strain contour and equating this to steam generator B of Turkey Point Unit 4 yields:

x 175

= 5 tubes 15 530 or a predicted occurrence of 5 tubes restricted to.540 over six months.

It is estimated that two additional months of operation beyond the current. six months would produce approximately 2 more

.540 tubes for a total of 7 such restricted tubes.

Although it would not. be expected that all of these

.540 restricted tubes would develop through wall cracks during a MSLB accident,,-

it would be conservative to assume that they would.

Even if the above number of tubes is doubled to allow for uncertainties, this is still within the assumptions made in the MSLB accident analysis performed in a previous submittal.

The use of a conservative crack aspect ratio of 6 for Turkey Point Unit 4 would yield a tight crack of length 0.3 inches when it be-came through wall.

Tests results indicate that such a crack would not burst below 5000 psid (well above differential pressures occurring during MSLB) and for differential pressures experienced during MSLB would yield a leakage of less than 0.05 GPM.

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Considering the 14 tubes postulated, it is estimated that this would result in a total increase in'leakage of:

14 leaks x 0.05 GPM/leak = 0.7 GPM

This, added to the.3 GPM leakage assumed to be present at the start of MSLB (which would increase to > 0.7 GPM due to MSLB hP),

yields a total leakage of > 1..4. GPM.

Thus even if the other two Unit 4 steam generators were included at this level of leakage, sensitivity analyses for steam linebreak show acceptable results for total leakage up to 10 GPM using NRC analytical assumptions.

Such a low leakage rate during MSLB would have a negligible effect on the DNBR transient, on. the percent of coolant volume lost by either contraction or leakage, and on the time to terminate the core transient.

LOCA effects previously analyzed still apply since these effects aie only dependent on the size and number of through wall cracks existing at the time of the accident.

The size and number of cracks are maintained below an acceptable quantity by the.3 GPM per steam generator operating limit already imposed.

The effect of secondary to primary leakage during LOCA would be negligible relative to primary system thermal hydraulic p'arameters when com-pared to the effects of the LOCA on these parameters.

RECEt YFO Orcut,k~tl

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