ML17301A097

Submits Info Re Pressurizer Heater Transformer Barrier Design,Per License Condition 2.C.9.Missile Protection Structure Will Be Seismically Anchored on Concrete Floor Slab

ML17301A097
Person / Time
Site:	Saint Lucie
Issue date:	02/27/1984
From:	Williams J FLORIDA POWER & LIGHT CO.
To:	Eisenhut D Office of Nuclear Reactor Regulation
References
RTR-NUREG-0843, RTR-NUREG-843 L-84-44, NUDOCS 8403010400
Download: ML17301A097 (5)

Text

REGULATO I. ORMATION DI'STRIBUTION ~ 8 (RIDS).

ACCESSION NBR:8403010400 DOCe DATE: 84/02/27 NOTARIZED: NO DOCKET P.

FACIL:50-389 St. Lucie Plant~ Unit 2p Florida Power 5 Light Co, 05000389 AUTH ~ NAME AUTHOR AFFILIATION WILLIAMS' ~ N. Florida Power L Light Co, @A RECIP.NAME RECIPIENT AFFILIATION EISEWHUT<D.G, Division of Licensing

SUBJECT:

Submits info r e pressur izer heater transformer barrier design~per License Condition 2 'D 9 'issile protection stl ucture will be seismically anchored on concrete floor slab.

DI'STRIBUTION CODE: A001S COPIES RECEI VED: LTR ENCL SIZE:

TITLE: OR Submittal; General Distribution NOTES:

RECIPIENT COPIES RECIPIENT COPIES ID CODE/NAME LTTR ENCL ID CODE/NAME LTTR ENCL NRR ORB3 ,BC 01 7 7 INTERNAL: ELD/HDS2 1 0 NRR/DE/MTEB 1 1 NRR/DL DIR 1 1 NRR/DL/CRAB 1 0 NRR/DSI ETB 1 1 NRR/DSI/RAB 1 1 R ILK OQ 1 1 RGN2 1 1 EXTERNAL: ACRS 09 e LPDR 03 1 1 NRC PDR 02 1 1 NSIC 05 1 NTIS 1 1 iTOTAL NUMBER OF COPIES REQUIRED: LTTR 25 ENCL 23

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3X 14000, JUNO BEACH, FL 33408 FLORIDA POWER & LIGHT COMPANY February 27, 1984 L-84-44 Office of Nuclear Reactor Regulations Attentionc Mr. Darrell G. Eisenhut, Director Division of Licensing U S Nuclear Regulatory Commission Washington, D.C. 20555

Dear Mr. Eisenhut:

RE1 ST. LUCIE PLANT - UNIT NO. 2 DOCKET 50-389 PRESSURIZER HEATER TRANSFORMER BARRIER DESIGN REF: 1) FPL letter L-82-429 dated October 29, 1982 from R.E. Uhrig (FPL) to D.G. Eisenhut (NRC)

2) NUREG 0843 Supplement 3 dated April 1983 In accordance with the St. Lucie Unit 2 operating license NPF-16, Condition of License 2.C.9, Florida Power & Light Company herewith submits the following information on the pressurizer Heater Transformer Barrier design.

During a 1982 Power Systems Branch site audit, the NRC identified "high energy equipment" (the Pressurizer Heater Transformers) in the cable spread area. Via Reference 1, FPL committed to install a suitable barrier around the, transformers prior to startup following the first refueling. Per Reference 2, the NRC stipulated that FPL's commitment is acceptable provided that prior to installation .FPL submit the barrier design and justification for NRC review and approval. The following is FPL's design philosophy for this barrier.

The Pressurizer Heater Buses are part of the onsite power distribution system.

The buses are comprised of a 480 volt class motor control center with a throat connected transformer. The transformers are 750KVA, 4 .16 KV to 480 volts, three phase. Any postulated failure of the Pressurizer Heater Transformers must somehow be initiated from the electrical system. FPL has assumed (non-mechanistically)an electrical failure which would increase the internal pressure of the transformer and cause it to rupture. The transformer is designed to operate below 5 psig with a relief valve set at that pressure> the tank is designed for 6.25 psig by the vendor. By using independent, conservative methods, the tank was determined to fail in different places at 10-16 psig.

However, the pressure used in the calculation was conservatively raised to 30 psig, which is a factor of almost five over the vendor information.

In this analysis, all appurtenances, regardless of attachment, were considered as'otential missiles. The velocity of a missile is dependent on its mass and cross sectional area, the driving force, and the distance to the barrier.

The driving force is the pressure that would cause tank rupture by seam 84030i0400 840227 i l PDR ADQCK 05000389 P PDR PEOPLE... SERVING P OPLE

splitting. The missile, therefore, is assumed to be driven out by the built-up pressure just prior to a tank failure. With the driving force and mass known for each object, the acceleration was found. The acceleration is used to

'determine the velocity of the missile. The velocity is required to determine the impactive force of the missile. A broad spectrum of large and small, heavy and light objects are considered as missiles to provide adequate loading combinations'o contain the missiles from the transformer, a barrier layout was prepared consisting of structural steel grating and a supporting structure. (see Figure

1) The important items considered were the penetration of the missiles through the grating and the impactive force on the grating.

The grating was designed as described in FSAR Section 3.5.3.1.2b.

It was assumed that only one missile at a time will hit the grating., It was determined that a grating thickness of 0.75" would be adequate. The openings in the grating were sized to contain the majority of the missiles. Certain .

very small missiles, however, were considered that might penetrate the barrier (e.g. a pipe plug). Structural steel plates will be installed on the grating in the front of these very small potential missiles.

Finally, the missile protection structure will be seismically anchored on floor slab. the'oncrete FPL concludes that this barrier will preclude damage to the cable spreading area in the highly unlikely event of a tank rupture.

I This concludes our reporting requirements to comply with condition of, license 2.C.9.

We intend to proceed with this design unless you have additional concerns.

Please contact us 'accordingly.

Very truly yours, J.W. Williams, Jr.

Vice President Nuclear Energy Attachment cc: J. P. O'Reilly, Region II Harold F. Reis, Esquire

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