ML18127B178

Forwards Information Required by Section E.1 of Enclosure 1 to Operating License; Florida Power & Light Co. Requests Condition E.1 to Be Removed

ML18127B178
Person / Time
Site:	Saint Lucie
Issue date:	07/28/1976
From:	Robert E. Uhrig Florida Power & Light Co
To:	Ziemann D Office of Nuclear Reactor Regulation
References
Download: ML18127B178 (11)

Text

U.S. NUCLEAR REGULATORY COP ION FROM:

Florida Power

& Light Company Miami, Florida Mr. Robert E. Uhrig TO:'r. Dennis L. Ziemann NRC FOR!w.495

{2-76) 4 NRC DISTRIBUTION FQR PART 50 DOCKET MATERIAL DOCKET NUMBER 50-335 FILE NUMBER DATE OF DOCUMENT 7/28/76 DATE RECEIVED 11/1/76 PKLETTER jQORIGINAL Ocopv DESCRIPTION ONOTORAZED PfUNC LASS IF I E D It PROP INPUT FORM ENCLOSURE NUMBER OF COPIES RECEIVED Two signed Ltr. trans the following:

NOTE: Three originals recvd./1 copy advanced to Hulman 8/2/76.

For distribution of small drawings, csee control 7/7713 ~

-Distribution as per R. Diggs-PLANT NAME'igure No. 1:

Hurricane Protection Figure No. 2:

Schematic 'Profile of Area between the Acid-Neutralization Basin and the East Groin w/

attachment B.

ACKNOWLEDGED St. Lucie gl (1-P) tt DO NOT REMOVE SAFETY ASSIGNED AD:

BRANCH CHIEF:

PROJECT MANAGER:

LIC ASST FOR ACTION/I Silver

- C NFORMATION ASS NEn AD ~

Pn 11 1 76.

RJL 8 FILE C

NRC PDR I&E OELD GOSSICK & STAFF MIPC CASE HANAUER E

INTERNALD SYSTEMS SAFETY HEINEMAN SCHROEDER ENGINEERING, MACCARRY SIWEIL PAWLICKI ISTR I OUTION BENAROYA IPPOLITO KRKW 0 OPERAT N REAC 0 S

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July 28, 1976 L-76-276 Director of Nuclear Reactor Regulation Attn:

Dennis L. Ziemann, Chief Operating Reactors Branch I2 Division of Operating Reactors U. S. Nuclear Regulatory Commission Washington, D.

C.

20555

Dear Mr. Ziemann:

Re:

St. Lucie Unit No.

1 (Docket No."-50-335)

Condition of License 'E.l I

"~

Enclosed herewith is the information required. by Section E.l of Enclosure,l to the St. Lucie Operating License.

H This information addresses erosion protection (Sheet pile groins and Bulkheads) near the eastern edge of the Ultimate Heat Sink and consists of two parts.

The analyses and drawings of Attachment A and the description of the neutral-ization basin structure provided by Attachment B are con-sidered sufficient to conclude that the erosion protection will function as intended during severe hurricane wave erosion conditions.

We, therefore, request that Condition E.l be removed from the St. Lucie Unit 1 Operating License.

Yours very truly, Robert E. Uhrig Vice President

,,,. (EIJÃilitk7 Attachments Ol 1Ig I)CI II/1~

'llIttlIG RI.~ (laIII.

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Norman C. Moseley, Region II (w/Attach less Figure 1 of Attachment A)

Jack R.

Newman, Esq.

(w/Attach, less Figure 1 of Attachment A) 776-]0 PEOPLE... SERVING PEOPLE

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Memorandum No.

13

SUBJECT:

WAVE ACTION AND SAND MOVEMENT AT THE EAST GROIN AREAR'.

The east groin at St. Lucie lies about 30 feet west of the corner of the neutralization basin.

The relation of the groin, neutralization basin, and the security fence between the two is Drawing 8770-G-516 Revision 2.

(See Fig. 1, attached).

memorandum will develop an estimate of the wave action and sand in this area of the plant island.

west the shown on This movement 2.

A schematic profile taken al'ong a north-south profile between the corner of the neutralization basin and the groin is shown on Fig. 2, attached.

An estimate of the wave action and the progressive changes that could be expected in the area during the NRC stalled hurricane (Peak

surge, 13.2 ft, MLW) and the Case 7 hurricane (peak surge 15.03 ft, MLW) are given in the following paragraphs.

The NRC Stalled Hurricane 3.

This hurricane surge is depicted on Fig 1B of Supp.

1, App. 2H, Rev.

37 8/22/75.

It has a peak surge elevation of 13.2 ft MLW occurring at Hour 59 into the hurricane.

This initial rise has a duration of about 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> (Hour 56 to Hour 65) above elevation +9.5 ft MLW with an average elevation of about +11.25 ft MLW, the peak being at +13.2 ft as stated above.

This initial peak is followed by other peaks of +12.8 ft (at Hour 72) and

+12.0 ft (at.Hour 84); these other two peaks, however, play no part in the east groin area as the wave directions are not from the N or NW.

4.

The wave action accompanying the +13.1 ft peak is about 6.5 feet as it approaches the groin area.

It is however approaching the shore at about 45; angle to the East (See Fig.

11 of Rev. 37) and would therefoxe be refracted as it moved onto the shore and broke; this refracted wave height would be about 5.6 feet.

At the average surge elevation of +11.25 ft for this initial rise, the refracted wave height would be about 5.0 ft.

5.

Actually some wave action would reach the east groin area 2 or 3 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> before Hour 56.

However, this wave action would 2 feet in height or less, so their overall effect at the east would be slight, particularly since the surge elevation would to bring a meaningful attack on the shore.

during the be only about groin area be too low 6.

When the surge reached about elevation +11 ft, the waves would begin to bite into the slope between the neutralization basin and Big Mud Creek as shown as Fig-2, attached.

This material would be dragged offshore in an attempt to,establish the equilibrium profile, fox this type of wave action.

As the surge rose in elevation the wave action would increase in height and more and'more material would be pulled out of the area between the neutralization basin and the east groin in an attempt to establish the equilibrium profile.

These waves would be between 4 ft and 5.6 ft in height and would tend to establish a bench at about elevation +8 or +9.

The duration of this initial rise is, as P

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Memorandum No.

13 (Cont.)

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stated in par. 3, about 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br />.

Using Fig.

9 of. Rev. 37, the cumulative erosion would be about 220 cubic feet.

7.

The existing ground elevation in the area between the east groin and the neutralization basin is at elevation +15.5 ft ML>1.

Thus, with a 34 ft cut into the'area at +9 ft, the height of.the face of the cut would be 6.5 feet (15.5 - 9.0).

The erosion, then, would be estimated at (220/6,5=)

34 feet.

The distance from the front slope to the toe of the roadway shoulder is about 80 feet, thus,'the material

,available in a one-foot width is about (80 x 6.5=) 520 cu ft.

There is,'herefore, available sufficient material to prevent the wave action from eroding into the

~ highway embankment, the indication being that the cutting action would extend only about 34 feet into the area under study in order to provide the 220 cu ft per foot of material called for in the preceding paragraph.

8.

Actually, the erosion would not be expected to extend this 34 feet for three reasons:

(a)

The average wave height would be about 5.0 feet, which is significantly less than the 6-foot wave height used in preparing Figure 9.

(b)

Much of the wave energy at the higher surge elevations would spill westerly over the east groin and not be available to erode the area east of the groin.

(c)

There is actually much more material in the area than was used in making the above calculations, as the area widens to about 80 feet to the east of the west coxner of the basin while the wave energy must enter in the 30 feet between the basin corner and the groin.

From the above, it can be concluded that the erosion into the groin area would probably not be over 20 or 25 feet for the first rise of the hurricane surge.

The two subsequent surge peaks would not have any significant erosion effect in the east groin as the waves would not be coming from dixections that would attack this area.

.9.

The preceding analysis carries with it the assumption that there would be no material moving westwardly along the plant island and brought to the east

~ groin area as littoral drift.

Instead, let it be assumed that a substantial quantity of material would be brought to the east groin as is predicted on pages 9 - ll of the erosion estimate section of Rev.

37 of 8/22/75.

The q'uestion in this case would be whether or not this material would be carried to the east groin where wave action might then drive it through the gap between the groin and the neutralization basin and then over the roadway embankment and into the emergency canal - intake canal complex.

Memorandum No. 13.(cont.)

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10.

To examine the above situation, let it be assumed that the surface areas and slopes in and around the east groin are paved and cannot erode.

Then a study will be made of what will happen to the littoral materials brought into this area by wave action.

Next let the wave run-up situation be examined when the surge level peaks at +13.2 ft MLW.

Under these conditions, the wave run-up would wash across the +15.5 ft MLW plateau at the rate of about 2.6 cu ft sec per foot of opening.

(See pages 7-39 of'Shore Protection Manual for method of computation).

With a 30-foot-opening between the neutralization basin and the east groin, the over-topping rate would be (30 x 2.6) 78 cu ft per sec.

This 78 cu ft pex sec-of overtopping water is equivalent to 280,000 cu ft per hr or 17.5 x 106 lbs of water per hr.

11.

One way of calculating the amount of sand carried onto the "plateau" by this overtopping water is to determine the concentration of sand to be expected in the overtopping water.

An examination of the literature'shows the following:

(a)

Watts.

BEB TM. 34, "Development and Field Tests of a Sample for Suspended Sediment in Wave Action," 1953.

Of the 290 field samples taken at Mission Bay, California for this study, a number were in waves 4.1 to 6.0 ft in height and in depths of 5 feet or less.

The highest average sand concentration (Figure 19) measured with pump-type samplers under these conditions was 1.2 parts per thousand by

'weight.

This concentration in the 17.5 x 106 lbs of overtopping water (paragraph

10) would total 21,000 lbs of sand.

At 2700 lbs of sand per cu yd, this would represent a total of 7.8 cu yds of sand per hour or 210 cu ft of sand per hour.

For the 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> that the peak "surge and wave direction were acting together at the east groin, the above rate would produce (9x210=)

1890 cu ft of sand or 70 cu yds for the 9-hour interval.

(b)

Fairchild, 1972 Proceedings, Coastal Engineering Conferenc Chapter 56, Vol. 11, "Longshore Transport of Suspended Sediment."

This reference reports on the suspended sediment concentrations measured in some 800 water samples taken for this specific purpose, using a pump-type sample, off the ocean piers at Ventnor, N. J.,

and at Nags Head, N. C.

An examination of the plot on Fig. 4 of this paper indicates that the single maximum concentration at Nags Head for waves about 3.25 feet in height was about 3.3 ppt by wt.

near the bottom and about 0.53 ppt by wt. near the top, for a maximum average concentration of 'about 1.9 ppt over the entire length.

This "maximum" average concentration (the outside envelope) converts to 2992 cu ft (110 cu yds) for

~ the 9 hour1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> interval as used in (a), above.

In this connection,.Fig 9 of this paper indicates that the sediment concentration does not vary significantly with the wave height.

Thus, the use of the concentration with the 3.25 foot wave height is con-

=

sidered justified.

(Note:

These concentrations are in general agreement with the concentration of 1.2 ppt shown on Figure 19 for Mission Bay in the report of (a) above.)

"3"

. Ãemoaaodum No.

13 (Co)

I (c)

The Fairchi,ld paper (Fig 12) also shows that in the large wave tank at the Coastal Engineering Research

Center, a concen-tration of as much as 10 ppt by weight measured in the bottom layers (less than one foot off the bottom) for waves about 4

feet in height.

This measurement is questionable as -a similar measurement with 6 to 6.5-foot waves gave concentrations of only 0.6 ppt.

However, if this 10 ppt measurement were used and assumed to represent the average concentration in the entire water mass, the quantity of sand carried ashore at the east groin site would be only 17320 cu ft (641 cu yds) for the 9-hour peak surge interval.

12.

The three sand columes in the preceding paragraph for the 9-hour peak surge interval (70 cu yds 110 - cu yds,'nd 641 cu yds) are

.recognized as being too small to cause any difficulty even if washed over the roadway and into the area near the junction of the emergency canal and the intake canal.

(The "safe" sand storage capacity of this junction area is well in excess of 10,000 cu yds.)

Some of the sand would probably be carried westerly over the east groin so that not all of the calculated volumes would be expected to move southerly over the roadway.

13.

Another quantitative indication of the ability of hurricane waves to carry sand over a coastal barrier is given in the April 1976 report "Hurricane Buelah and Camille:

An Evaluation of Erosive Impact" prepared by Envirosphere Company for Florida Power and Light. Company.

This report reviewed'ntensively the history of averwashes on South Padre Island (Buelah) and the Mississippi Delta area (Camille).

The summary in the report states (Page 4) that the volume of overwash varied from 1.05 to 20.3 cubic yards of sand per foot of breach width.

Using the higher figure of 20.3 cu yd per foot for the 30-foot gap between the neutralization basin and the east groin, this would give an estimate of. 609 cu yds of sand.

It should be recognized, however, that the Buelah and Camille events, involved breaching of the dune line accompanied, no doubt, by considerable flow velocities through the breach.

In the absence of a breaching action near the east groin (see pars 8 and 9 above), it could not be expected that the rate of overwash would approach the 20.3 cubic yards per foot reported as an 'observed maximum in the Envirosphere report.

14.

Another point to be noted is that the sand overwash quantities of 70,

110, and 641 cu yds per hr of par. il were based on the assumption that the surge stood at the elevation of +13.2 ft MLH foi'he entire 9 hours1.041667e-4 days <br />0.0025 hours <br />1.488095e-5 weeks <br />3.4245e-6 months <br /> of the peaking interval.

Actually, the average elevation during the peaking interval is about +11.25 ft MLH.

At +11.25 ft elevation with a wave height (after refraction) of 5.0 ft.

The overtopping note for this average condition would be slightly less than 1.0 cfs per foot of width as compared to the 2.6 cu ft / sec of par.

10.

Thus, the quantity of sand overwash for the 9-hour peaking interval would be represented by figures of 27, 42 and 246 cu ft of sand per hour when based on the average overwash conditions for the 9-hour peaking interval rather than applying the overwash conditions at, the +13.2 feet MM instantaneous peak to the entire 9-hour interval.

Memorandum No.

13 (Cont.)

15.

The conclusion from the above analyses of the as-installed condition of the east groin, wave barrier wall and the NRC stalled hurricane in-dicates that there would be no breaching of the roadway behind the barrier and no serious overwash of sand onto=or across the area behind the 'east groin.

I' 16.

A review of other PHH situations showed that one of these (Case 7) might produce more severe erosion than the NRC stalled hurricane.

Thus an

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'nalysis similar to the above was made for the Cas'e 7 hurricane; this hurri-cane had a max. wind radius of 20 miles and a txansitional speed of 4 knots and a pressure differential of 5 in. mercury.

Its peak surge height*was'

+15;03 ft 1K'ith a duration of 13 hours1.50463e-4 days <br />0.00361 hours <br />2.149471e-5 weeks <br />4.9465e-6 months <br /> above +8.0 ft MLU.

This surge was divided into two steps for this study:

one, a high step, a +15.0 ft elevation assumed to last for 3.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />, and one a lower step at +11.0 Et assumed to last for 9.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br />.

The waves for these two steps were 7.6 feet and 4.7 feet respectively.,

The erosion resulting, from the first step would be 23 Eeet and from the second step 15 feet, for a total'of 38 feet.

This is 4 feet more than the 34 feet computed in paragraph 7, above..

17.

As a next step, the amount of sand that might be carried landward was computed for the Case 7 hurricane in the same'anner as was used for the NRC stalled hurricane in paragraphs 9-12, above.

The same two steps as described in paragraph 16 were used for the Case 7 hurricane.

The results indicate that, for a sediment concentration of 1.9 ppt by weight in the overtopping water, a total of 255 cu yds of sand would be carried inland between the neutralization basin and the east groin.

For a sediment concentration of 10 ppt by wt., the quantity would be 1342 cu yds.

- This compares with totals of 110 cu yds and 641 cu yds respectively for the sand

'oVerwash quantities given for the NRC stalled hurricane in paragraph 12, above.

As indicated in the text of this memorandum, the smaller overwash figures of 255 cu yds and 110 cu yds are considered to be the more realistic.

figures, as they are based on the maximum average concentration throughout-

, the water mass rather than on a single'aximum concentration measured very near the bo'ttom.

4 18.

The figures given for potential erosion and potential sand overwash for the NRC stalled huxricane'nd the Case 7 hurricane indicates that no severe c'onditions would develop in the east groin area from either cause or from a combination of the two.

Thus, it can be concluded that no further treatment of this area is needed to defend against sand overtopping-.or wave erosion.

Joseph M. Caldwell Consulting Engineer, NfC pf

. 2 incl.

Pig.

1.Plan Fi5. 2 Profile 0

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