ML20101S765

Forwards Responses to NRC 850109 Questions Re Util 840917 Submittal of Riverborne Missiles Supplemental Info.Required Analyses Underway.Results Will Be Forwarded by 850220

ML20101S765
Person / Time
Site:	Hope Creek
Issue date:	01/31/1985
From:	Mittl R Public Service Enterprise Group
To:	Schwencer A Office of Nuclear Reactor Regulation
References
NUDOCS 8502050630
Download: ML20101S765 (25)

Text

,

f O PS G Company Pubhc Sennce Electnc and Gas 80 Park Plaza, Newark, NJ 07101/ 201430-8217 MAILING ADDRESS / P.O. Box 670, Newark, NJ 07101 Robert L. Mitti General Manager Nuclear Assurance and Regulation January 31, 1985 Director of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission 7920 Norfolk Avenue Bethesda, Maryland 20814 Attention:

Mr. Albert Schwencer, Chief Licensing Branch 2 Division of Licensing Gentlemen HOPE CREEK GENERATING STATION DOCKET NO. 50-354 RIVERBORNE MISSILES SUPPLEMENTAL INFORMATION On December 18, 1984, representatives of PSE&G met with the NRC staff to discuss comments raised by the staff on PSE&G's September 17, 1984 submittal of supplemental information on riverborne missiles. After that meeting, the NRC formally transmitted these comments as questions in 'a letter to PSE&G on January 9,1985 (A. Schwencer to R. L. Mittl).

Our response to these questions is attached. In a few instances we are completing required analyses which will be forwarded to you by approximately February 20, 1985.

Should you have any questions or require any additional information on our submittal, please contact R. P. Douglas, Manager - Licensing and Analysis, of our staff.

Very truly yours, g

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A. R. Blough (w/ attach.)

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. HOPE CREEK GENERATING STATION PUBLIC. SERVICE ELECTRIC AND GAS COMPANY RESPONSES TO QUESTIONS IN JANUARY 9, 1985 LETTER RIVERBORNE MISSILES

- Question 1 1Your analysis of waterborne missiles has been limited to the hurricane flooding event.

a) Using the combined event criteria cited in ANS 2.8-1981, provide your detailed

-analysis of the water levels associated with the Probable Maximum' Flood (PMF) on the Delaware River at the Hope Creek il Plant.

Use appropriate hydrologic models which input the 10 percent excedence high tide and the PMF hydrograph as the upstream input condition, b).Using the combined event criteria, provide your analysis of the water levels at the plantLsite associated with the seismic dam failure combined

.with.the one-half PMP. event on the entire river basin and thel 10. percent excedence high tide at the plant site.

IResponse Section 2.4.4 of-the FSAR includes analyses of the effects 6

of single and multiple dam failures on flood levels at the Hope Creek site.

The analyses presented were based on the assumption that the previously proposed'Tocks Island Dam would be: built.

A' review of recent developments has lead us to.the conclusion that'the proposed Tocks Island Dam is no longer a viable project.for the foreseeable future.

Our

. conclusion is' based on the following:

.The Tocks Island. Project'was. originally conceived in the

~

early:1960s to. provide flood' control and water supply'in

the ' middle. Delaware region.'

Funding was provided to the Army Corps'of Engineers until 1975.for. design, planning,.

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11andJacquisition,.and project 1 review..In 1975V the

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-Delaware 1 River : Basin-Commission.(DRBC) voted -to ask

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< Congress to stop funding the project.and voted to putLit e-on reserve status.

In 1978,l Congress passed PL 95-625 whichc included - in' the' Wild 'and Scenic River. System the -

section of the" Delaware) River that'is' bounded by the

~

DelawarezWater Gap; National Recreation Area, much of..

.which would.have.:been inundated had the: dam been built.

+ '.

In11983,.theVDRBCipassed'a:. resolution'(No. 83-27) to.

f

. amend'its Comprehensive _ Plan to' revise and' update the 1

description ~of the-project.

According to-the resolution, the, project has been' placed in reserve for - development if mi needed i fori waterEsupply. af ter.;the ; year 2000.

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If the'DRBC were to vote for development of Tocks Island

-r at the-turn of the century, Congress would have to recon-sider the matter during the appropriation process and would.also have to alter the designation of that section of' the river under the. Wild and Scenic River System.

The considerable opposition to the project in the early 1970s would probably resurface to slow or halt Congressional action and the permitting process.

Based on the above, we.have deleted consideration of the

-Tocks Island Dam in our analyses that follow.

The flooding effect caused by the Probable Maximum Flood and one-half Probable' Maximum Flood were evaluated concurrently with the ten percent exceedence high tide level at the site using a one-dim,ensional backwater computer model (Reference 1).

The dam flood analyses'were evaluated following a one-dimensional flood wave routing procedure (Reference 2).

The events are assured to be independent;and therefore, the resulting flood depth caused by one-half. PMP and dam failure flood - represents the superposition of the - independent events.

The flood depth estimated for each event is referenced to the National Geodetic Vertical Datum (NGVD).

The magnitude of the Probable Maximum Flood, 1,250,000_cfs, represents the PMF for the entire drainage basin, an area of 12,765 square miles.

This was estimated ~following the enveloping isoline technique described

.in Regulatory Guide.l.59'(Reference 3).

For.the evaluation of PMF~and one-half PMF,~

it was ' considered that the peak flood eleva-

tion occurs at -the fsite : location concurrent -

with the peak discharge based on gradually varied flow a'ssumpt' ions generally applicable to rierine flooding.

Hence, a one-dimen-

.sional backwater. profile modelican be used.

The cross sections were.obtained using NOAA

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National. Ocean Survey Nautical charts with soundings and elevations converted to NGVD (References 4 and,5).

A total of'seven cross sections were taken starting from the s

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Delaware Bay.at Murderkill River to Reedy Point.. A-composite Manning's roughness co-Jef ficient Lyalue lof 0.03 was used for the

- backwater profile'model.

Trail runs were made -for 'both PMF and one-half PMF with starting water. surface elevations equivalent to -the ten percent exceedence high tide ap-

. proximately,4.2 feet (NGVD), and Mean High

' Water at Murderkill River, 3.2 feet'(NGVD).

For the evaluation of single dam failure flood, Francis E. Walter dam was considered m

-while multiple dam failure considered seis-

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-mically-induced failure of'Pepaction Dam and

.Connonsville Dam instead of Tock's Island Dam.

This. procedure was also used for the

. preparation of the Safety Analysis. Report.

Starting with evaluating. peak dam failure

. discharge andfflood stage at the dam site the: dam flood was then routed to the HCGS site.

Variables.used for the routing analy-sis 1 include total: flood release volume and valley storage index.which represents the storageEeffectuof the valley and the chan-nel.,

Results.give the attentuated peak dis-charge and flood stage which is referenced to the. mean sea level.

For.the estimation'of.the water flow

velocity, the values of each contributing Levent was evaluated independently.

Mean'

. current velocities associated with the PMF

'and:one-half PMP.'were calculated in the backwater' profile.model.

VelocitiesJas-:

sociated_with dam floods,were estimated

using; simplified peak discharge, flow area

calculation.

To incorporate the wind ef-ifects thelsurface' wind-induced current ^

velocities,are conservatively' assumed t'o be -

approximately 5' percent ofi the 10-meter. wind

. speed.1.Bretschneider-(Reference 6i) and.

Saylor (Reference'7):have concluded that 2' c

t'o 3% ofithe' wind speed! represents an 1

/

average range of' wind-induced currents

^

speed. ;Further,'the wind velocity,in the surface'fri,ctionclayer above;the water sur-f ace 'was ~ estimated ' based on' the ' l/7 th power -

ilaw of the1 vertical' wind velocity distribu--

- tion.- 1 The' thickness of ' the.frictionElayer 4

. as(assumed to be about 0.6 cm (Reference-p w

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The wave-induced horizontal orbital velocity was also calculated based on methods described in the Shore Protection Manual ~(Reference 8).

-For the wind and wave-induced current compu-tations, the wind condition used is the 2-year sustained extreme wind, approximately 50 mph in the study area.

Tables 1 and 2 present the results of the flood elevation and current velocity estimates.

From this~ analysis, the flood

~

elevation associated.with PMF is approx-imately 7.6 ft (NGVD) concurrent with ten

-percent exceedence high tide.

The multiple dam failure scenario results in a flood level of about 11.4 feet (NVGD) including one-half PMF and ten percent exceedence high tide which is approximately 1.0 feet above the plant grade, 10.5 feet (NVGD) at the service water intake structure.

However, all flood elevations are below the plant grade of 12.5 feet (NGVD) at the Reactor Building.

For a 2-year extreme wind speed of 50 mph, the wind speed in the surface friction layer can be as high as 25 feet per second.

The average current velocity con-sidering ef fects from multiple dam f ailure, with one-half PMF, wind and wave ~ induced ef-L fects is approximately 16 fps as estimated

'by supe rposition.

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E TABLE 1 r

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. WATER LEVEL ELEVATION ESTIMATES EVENT ELEVATIONS (NGVD)

(feet) 1.

Probable Maximum Flood 7.6 with 10% exceedence high tide 2.

One-half probable maximum flood 5.4

-with 10%:exceedence high tide 3.-

Single dam tailing with one-half 10.4 PMF and 10% exceedence high tide

. 4.

. Multiple dam tailing with one-half 11.4 PMF and'10% exceedence high tide f

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- TABLE 2 CURRENT VELOCITY ESTIMATE i

EVENT VELOCITY (fps)

-1.

Probable Maximum Flood ~

4

- :2. -One-half Probable Maximum Flood 2

3.

~ Single dam failure 4

4.-

Multiple dam failure 4

5.

' Wind-induced longshore current 4

6.

Wave-in'duced surface horizontal 6

orbital velocity Velocity of Combined Events by Superposition

- l+5+6 14 2+4+5+6 16 (worst case)-

2+3+5+6 16 (worst case) s

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~. REFERENCES FOR OUESTION 1 1.

.U.S.--Army CoEps..of. Engineers.

The Hydrologic Engineering Center.. September-1982.

HEC-2 water surface profile, corporate program.

2.

.Snyder,nF.F.,_ Hydrology of Spillway Design: Large Structures-Adequate Data._ Journal of Hydraulics

' Division, Proceedings, ASCE HY3, May 1964.

' 3.

U.S. Nuclear Regulatory Commission, August 1977.,

Regulatory. Guide 1.59, Design Basis Floods for Nuclear Power Plants. -

4..

U.S.

Dept. of Commerce, NOAA, NOS., Nautical Chart 12311, Delaware River, Smyra River to Wilmington, September 83 and Nautical: Chart 12304, Delaware Bay, October 19 83.

5.

Mr.~ Milton'Rustein, Chief, Tidal-Datum Section.

Personal Communication.

Conversion of MLW level to MSLL

'MGVD, 1929. along. Delaware River, January 3,1985.

~

6.

.Bretschneidr, C.L.,

Storm Surges in Advances in (Hydrosciences (Ed. V. T. Chow), Vol. 4, 1967.

Academic

-Press, N.Y.

~

7.' _ Say1or,' J.H.~,1 Currents at Little Lake Harbor.

Lake

~

Superior,; U.S. - Lake Survey Res. Dep. No. H., Lake Survey

District,.U.S. E Army Corps of 1 Engineers, 1966.

8.1 U.S.~ Army' Corps of Engineers,_-1984.

Shore Protection L Ma nual, ;Vo l.1 1, prepared by Coastal' Engineering Research

Center, Dept. of the Army, Waterway Experimental

Station.

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Ouestion 2' Discuss the impact of waterborne missiles, derived from up-stream industrial areas as a result of these flooding events, on safety-related structures including the waterproof doors.

Response

The safety related structures of concern to the flooding generated missile analysis are the service water intakes structure and the doors on the power-block.

The service water intake structure is addressed in Ouestion 3.

As f ar as waterborne missiles derived from upstream industrial areas are concerned, they are no threat to the waterproof doors on the power block since these missiles could not' traverse the plant site.

The answer to Ouestion 1 indicates'that the extreme water level due to flooding initiated from the north (upstream) results in a water level of 11.4 ft. above Mean Sea Level at the location of the plant..The water. level is therefore about 1 ft. below plant grade and floating missiles could not enter the plant site

-and-impact the. power block doors.

Ouestion 3 Discuss _the ability of the service water intake structure to resist the impact of waterborne missiles (boats, barges,

'etc.) from upstream sources.

Response

To be provided later.

Question 4

Discuss the ability of exterior doors in safety-related

-structures.to withstand the impact of a spectrum of water-borne' missiles'and identify the limit of the doors to resist thel impact of the missile spectrum.

' Response

.As' indicated in answer to'Ouestion 1,~the worst' postulated flood originating from the. north (Ouestion ]b) wo'uld lead to a water level of II.4 ; f t.. over Mean Sea Level in the vicin-

ity'of'the Hope Creek Station.x This water level is about

• 1;ft. below plant grade.

As such, the power block doors are

,not exposed to missiles originating north of the plant.

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MP85'.27/08 8-db

The ADL~ Report analyzed the missiles which could impact the

~

doors in the event of extreme wind event generated high water.

As indicated in the ADL Report, very severe hur-c ricanes on a highly specific trajectory could cause the water level to' raise over plant grade allowing for the pos-sible; impact between waterborne missiles and the power block doors.

The results of an impact analysis described in the ADL. Report' indicate that the doors will maintain leak-tightness 'for the full spectrum of missiles.

The most

- severe-impact results from a very large recreational boat (25,000 lbs.) impacting a door on a 10" round cross-section

'7 This results in an im with.a 20 mph velocity.

f t.-lbs. per f tgact energy per unit area of about 500,000 Although for impact energies in excess of the above values, the. leak tightness of certain doors could be compromised, the extreme-conservations in the assumptions on the mass of therboat, cross-sectional area and impact velocity result in ic_

this case being one that. bounds by a wide margin potential

- missiles that--could reach safety-related structures on site.

Question-5

' Provide.the uncertainty associated with.the extrapolation of -

-a n 11 year' data base to represent return periods of up to 200 : years, particularly in the development of a relationship

-between extreme wind speed and wind direction.

Response

To be provided later.

' Ouestion 6 Provide.further justification of the use of the " Fisher-

~

Tippett Type 2" distribution when-other analyses of extreme windsT(e.g.,.NUREG/CR-2639,3 " Historical Extreme Winds for

- the United-States-Atlantic and Gulf 1of Mexico Coastlines")

suggest use of a mixed: distribution, with all type I distri--

o

. - bution1 fitting non-tropical storms and=the.Weibull distribu-tion fitting tropical. storms.-

Response

To be.providedflater.

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C Ouestion 7 The-statement is made on page 2 that "the particularly open exposure of this site -is not adequately duplicated at any of the' National Weather Service (NWS) stations in the region,"

' implying that extreme wind speeds at the site may be higher than at the NWS-stations.

Provide a discussion of the ex-

posure of NWS stations in the region, particularly at Wilmington, Delaware, and provide comparable estimates of extreme' winds at the-NWS stations for return periods of 20, 50, 100, and 200 years as in Table 2.

Response

To be provided later.

Question 8 Typically, extreme winds are represented by the fastest mile

- winds peed.

Provide a-comparison of fastest mile wind speeds

- for return periods of 20, 50, 100, and 200 years between regional NWS stations and the site.

Response

To.be provided later.

Question 9 Sustained winds with durations of 10 minutes are often examined to determine wave action, run-up and surges.

Pro-vide additional discussion and justification.for use of

. l. hour and 6 hour6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> averages of wind speed for consideration of the effects of winds on riverborne missiles at Hope

. Creek.

Response

- In'the evaluation of the effects of hurricanes on riverborne missiles, five different storms were analyzed; PMH, model

,L hurricane, and three other storms with maximum wind speeds between. that of the PMH-and the model hurricane. -The max-imum wind speeds-used were by definition, the surface wind which is considered to be that which would be observed at 30

. feet above the surface of.the water whose speed is a 10

. minute ~ average.

This parameter is part of the input to the computer program for. computing surge on the open coast and routing up the Delaware Bay.

The program considers the com-plete wind field associated with that maximun wind.

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'In calculating.the open coast surge resulting from extreme s

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wind-events other than those accompanying hurricanes, we consider.that the ' winds would have to be blowing for an ex-tended period of time to obtain steady state conditions.

We used maximum hourly wind speeds of.200, 100, 50, and 25 year

~ recurrence intervals and assumed that they persisted un-

.diminshed for six hours.

A storm which would produce the

-maximum : hourly wind would have associated with it a higher

'10 minute: wind speed.

However, it.would be the speed of longer durationzthat would develop the surge.

Therefore, xthe. surge ~ values developed.are conservative and reflect a wind : field with somewhat higher 10 minute wind. speed.

'In calculating the effects of winds at the site, we assumed

the localized wind conditions would result only in cross

-wind l set-up or set-down.

The time required to achieve this

.value is~ a1 function of wind. speed, fetch and water depth.

lFor 50: mph winds, it is on the order.of one hour.

Winds of hurricane force 140 mph.would require 30 minutes.

There-fore,~our use of the one hour wind is appropriate.

Quest' ion 10 tThe : attempt to quantify.the probability of occurrence of a

' probable maximum hurricane.(PMH) with a trajectory west of Artificial Island appears somewhat misguided, considering the deterministic deviation of the PMH-parameters and the considerable uncertainties associated with hurricane trajec-tories = prior;to 1871.

Provide' additional discussion of the

' relationship'of the PMH to trajectory, considering in, par-ticular the number of. hurricanes which;have or appear to

'have passed west of Artificial Island since 1683 (about-six?)'and that none of the observed-hurricanes approached the'intensityLof the PMH.

Response

.Please-refer toltheLresponse'to Question 21.

, Quest' ion 111

.The.relationshipfbetween. wind speed magnitude, direction, and duration appears; crucial 1for this analysis.

Although relationships <between, fastest mile wind speeds and sustained

winds for 1 minute'orJ10' minute periods are available, the

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relationship.between the direction of sustained winds is not

^

(well-estrblished.-l Provide additional' discussion of the.

ai 1 relationship offextreme wind speeds.to wind direction in the icontext offriverborne' missiles at' Hope Creek..

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- Response-In-the MES studyLof the fastest-mile data for the 11 year period of site' data, the six hour periods of maximum sus-l tained win'ds in'the direction sector of concern (79'-170*)

- was selected and then the. fastest-mile wind peak occurring

. within-that time. period-was determined.

The fastest-mile

-wind was therefore within this same direction' sector, al-

~

thoughLnot pinpointed in the exact direction at the time of the fastest-mile' occurrence.

Since the fastest-mile data

_themselves:have little to do with the development of the 1 major surge, their specific directions.are irrelevant, ex-cept possibly with respect.to the movement of floating ob-Jjects during the last few miles before reaching shore.

Also, please see'the response ~to question 9.

i Question 12-i Provide-the details of your analysis performed to evaluate

.effectscon' power block structures and the intake structure due to the. impact of the waterborne missile.

These details

'shouldcinclude, at least, the following:

a.

Assumptions,-Basis and Results..

'b.

-Criteria used-in evaluations.

'c.

? Evaluation lof local-effects,Eincluding spalling of con-crete-on inside: faces, potential impact on the safety-related' equipments. nearby, and leakage potential.

d.

Overall effect of the' waterborne missile'on the structu-

. ral' elements and doors, L and _ boundary mechanics. by' which

the impact forcesfare. transmitted.from the door to.the structure.

e'.

Overal11 stability of intake structure.

f.'.Any high frequency 7 vibration effects'on_the attached 3 equipment.

Response

a.

The3 evaluation.of.the impact is based on the following:

Assumptions:

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.MP85:27/08 12-db-s

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la The types of. missiles evaluated are described in the report "An Analysis of the Likelihood of Waterborne Traffic and Other Floating _ Objects on the Delaware River Impacting the Hope Creek Generating Station in Severe, Storms" prepared by Arthur D.

Little (ADL),

Inc., September 1984.

o The impact phenomenon caused by the waterborne mis-siles on the structure is assumed to be similar to that of an automobile missile impacting on rigid target under a tornado event.

As a result, the forc-ing. function of the impact is assumed to be the same as that of an automobile impact, as described in Bechtel Topical Report 1BC-TOP-9A, " Design of Struc-tures for Missile Impact," September 1974 (PSAR Reference No. 3.5-4).

o The nature of the impact is assumed to be plastic in which all of the missile momentum is transferred to

'the target.

Basis:

o Standard Review Plan, NUREG 0800, Section 3.5.3 is used as the basis of evaluation.

Results:

o Based on the missiles defined in the ADL Report, recreational boat type missile weighing 25 kips traveling at 20 mph is determined to be critical.

o-Using extremely conservative assumption of rigid mis-sile and the equivalent contact-area of impact to be only 10. inches in diameter, the depth of

' perforation'is estimated to be approximately-

30. percent of the thickness of the thinnest wall (30 inches).

Consequently, no adverse local damage is anticipated.

o' In evaluating overall. damage it is determined that the requirements of ductility ratios as described in Appendix A, Section: 3.5.3 of NUREG - 800 have been met.

As a' result, the overall structural integrity u^

will not be adversely af fected by the impact.

o=

Based on the above, it is concluded that the structure lwill remain leaktight following the postu-

~1ated impact.

MP85 27/08 13-db--

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b.

The criteria used for the evaluation are contained in the following references:

o Hope Creek Generating Station Final Safety Analysis Report (FSAR),' Docket No. 50-354.

o USNRC Standard Review Plan, Section 3.5.3 of NUREG-0800.

c.

Since the mass of the intake structure and the thickness of the exterior. walls are considerably less than those of'the power block, it is determined that evaluation of the intake structure will provide conservative results for concrete structural elements.

The water depth associated with the unlikely, probable

maximum hurricane event is expected to reach 40 ft. at the intake structure ( ADL Report, page 8).

At this water depth, the design missile is postulated to strike the structure at the western outside shear wall between elevation 100 ft. and elevation 128 ft.

For the poten-tial area of impact, this shear wall has a uniform con-crete thickness of 30 inches.

Perforation and spalling of the impacted shear wall are evaluated by using formulae for rigid missiles.

The

-thickness' required to prevent perforation is found to be approximately 10 in., which is substantially less than the wall thickness (30'in.).

Since the design missile

-is a soft missile, the value obtained is very conserva-tive.

Based on the shape-and the characteristics of the

-design missile, and the extremely conservative impact area used in the calculations, the spalling on the

.inside face of the impacted wall will not occur and, the leak tightness of the wall will be maintained after the impact.

Since all safety related equipment is located inside the structure and away from the potential impact area, a direct hit by the design missile on the equipment is not possible.

Furthermore, since spalling of the impacted concrete wall is unlikely, the impact of secondary mis-siles on the equipment need not be considered.

1d.

.The calculated peak impact force is on the order of 4.6 x.-105 lbs., and-the required shear force to punch through the wall is 1.4 x 106 lbs.

Since the punching shear. force is more than twice the peak impact force, MP85 27/08 14-db

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sthe concrete structural elements are determined to be

capable of maintaining their integrity during and af ter the impact.

Evaluation :on the leak tightness and the. structural integrity of:the door'is;given in ADL Report (page 20 and page 21).

It-is determined that all doors are cap-

able'of maintaining both the leak tightness and the structural integrity under the missile impact.

.e..-The peak impact force caused by the waterborne missile isionly a'small -fraction. of the total' weight of the

~

- structures. fTherefore, the stability of the Category I

' Structures will not be adversely affected by the 7 postulated impact.

f.

Using :the' conservative 1 fundamental mode frequency of the fix base' intake structu're-(13.5.Hz), the average accele-

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E ration level of the structure is found to be about i^

' O '. 0 5 g.1 The design SSE acceleration (0.2g) is signifi-fcantly.higherfthan1the average global acceleration level

~ of. the1 structure.. The l maximum local acceleration level b

at the-impact location, :which is conservatively assumed ntolbe at the center of the impacted wall, is found to be

-1.50g.

This acceleration will_ generally : attenuate away

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from the impact location. _ For equipment which is

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' located away from the~ impacted wall, the high frequency

vibration-effect presents no problem.

For the traveling

. water screen',-which~is located closest to the impacted wall, the;above two acceleration levels are still smal-1er-than 'the design. spectral 'value 'of - 1.6g which corres-

pondsito.the Safe-shutdown ~ Earthquake..Therefore, high

< frequency: vibration effects caused by the waterborne missileHdo )not result inJa problem to safety related-

- ~

" equipment. located in :the; intake structure.

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V Ouestion 13 For.those structures and. doors wh'ich mayfleak or fail or

-generate Lsecondary ' missiles, -provide the results of any 0

l analysis'~of-the : ef fects of. the secondary' miss'iles' and. flood-Lingion safety-related systems -and components.

Credit for 1any mitigating action _canLonlyfbe taken for safety-related-r -/

. Class lE powered: structures, ' systems, and components.

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? Response YIY l -,

(See response to'Ouestion'12c.-

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-Ouestion 14 h

On.page;5 of.the ADL Report, it is stated that grade level is approximately'14 ft. above Mean Low Water Level.

In

. Table 2,. footnote 4, page.7, it'is stated that an increased

~

water depth of 12 ft. over Mean Low Water results in a water l

. level ~which.is about 3 ft. below plant grade.(rather-than 2.ft.,,as.would. result from the statement on page 5 of the ADL' Report).

Is there a reason for the difference between f

the statements in page 5 and in Table 2?

T

-Response The' elevation and water height numbers in-the ADL Report are j"

-approximate to within about 1 foot.

This approximation does not compromise the analysis or change any conclusion.

The most recent measures of datum and water level relationships are contained in1 Figures 2.4-3gof the Hope Creek Final Safety Analysis Report.

A copy of Figure 2.4-3 dated

october?l983 is attached.

It can be seen from this figure that plant grade is actually 15.1 ft. above Mean Low Water. - Under the postulated extreme.

wind scenario the-water level could rise up to 12 ft, over Mean_ Low Water.

.In this case,.the water level would still

.be about 3 ft. below plant grade.

Question 15 It -appears ~ implicit?in the estimate of the ~ kinetic energy per unit area for a large recreational boat 'hittin

structure _ :(page 16) that-the impact area is = 100 'f tg a

~

Ex-plain why the impact areas could not be significantly

- smaller than 100 f t2,.

Response

The~ discussion on.page 16 is presented only as aLhypothe-tical example.

In order--for a 10 ton recreational boat to i=

impact a rigid: concrete structure and not sustain damage to itself (so,as to look at the worst-case damage'to the-intake structure) aDstructurally-strong segment of the recreational

~

-boat-would have;to be the impact point.. Such a strong seg :

. ment is unlikely to exist:on a recreational boat, but if it

-did, it may likely;have the 100 ft2 surface' area..

-However, the discussion on page 16 is only~a general narra-

t. -.

.t'ive?ofia postulated scenario..The actual values used for

~

lthe impact: area in the door _ integrity analysis was about 1

~

jy #

I

'MP85;27/08.16-db

~. ~=

a

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).,.

i l

MSL PSEEG MAXIMUM WAVE RUNUP HEIGHT, FETCH NO.1,

. 34,3 _

323,3 d L PROSABLE MAXIMUM SURGE MAXIMUM WAVE RUNUP MElGHT, FETCH N0.2, 31.0 -

120.0 O

PR0SA8LE MAXlMUM SURGE MAXIMUM WAVE RUNUP HEIGHT, i

26.3 -

115 3 MILTIPLE DAM FAILURES MAXIMUM WAVE RUNUP HEIGHT, 21.6 -

110.6 SINGLE DAM FAILURE 20.8 -

109.8 MAXIMUM WAVE RUNUP ME1GMT, DELAWARE RIVER PMF 18.1 -

107.1 MAXIMUM WAVE RUNUP HEIGHT, TSUNAMI WAVES 22.5' 26.3' 12.5 -

101.5 PLANT GRADE 9

4.0' 8.5 -

97.5 l l HIST 0AlCAL HIGH WATER (NOVEMBER 1950) 8.5' MEAN HIGH WATER 3.2 -

92.2 n

9 2.9' 89.3 MEAN TIDE LEVEL i

0-89.0 MTu"E 'Mu M uuuu MEAN SEA LEVEL (SANDY HOOK 1929 ADJUSTMENT) 2.68 2.9' NATIONAL GEODETIC VERTICAL DATUM

-2.6 -

86.4 MEAN LOW WATER 8.0'

-8.0-81.0 HISTORICAL LOW WATER (DECEM8ER 31, 1962) l 93,ge l

l'

[

- 13.0 -

/6.0 EXTREME LOW WATER - DESIGN HO9E CREEK j

GENERATING STATION i

I FINAL SAFETY ANALYSI3 REPORT I

DATUM AND WATER LEVEL RELATIONSHIP t

FIGURE 2.4 3 AMENDMENT 2,10/83

-ft2 as represented by a 10" round cross-section discussed on page 19 of the ADL Report.

-Also, a very large recreational boat weighing 25,000 lbs. was considered in the analysis

-(see page 19 of the ADL Report).

Both the size and impact are conservative in that they result in a very large energy per unit area being transmitted to the doors.

Ouestion 16 Explain why the chances of an unmanned vessel approaching within 10 miles of Hope Creek without a prior grounding are estimated on page 44, Appendix C of the ADL Report, to be less than 10 percent?

Response

The unmanned vessels which could break free from a barge tow in the highly unlikely event of a barge tow being anchored on the Delaware substantially south of Artificial Island in an ' extreme wind event would be a barge.

Of the three major types of barges, an open top hopper barge with its two to three feet freeboard would probably sink within a few minutes under the postulated extreme wind and water condi-tions.

A closed top sea-going barge or a liquid cargo barge could survive longer provided it is not punctured due to im-pact with other floating objects (debris) which would be present in the river during the postulated storms.

However, because of surface currents and wind driven " sail area" ef-fects, the barge would be pushed towards the banks of the river where it will ground in the shallows prior to substan-tial. movement towards the plant.

Subsequent to grounding, it would be impacted by floating debris and could sink.

The barge could also undergo some additional movement, but we do not consider this likely.

Based on the above unmanned ves-sel movement scenario, it was assumed that the likelihood of such a vessel approaching.a location within 10 miles south of the plant prior to sinking or grounding was less than 10 percent.

JOuestion 17 It is assumed in the ADL Report (page 45)'that the proba-bility per mile of simultaneous loss of power and steering is A = 10-5/ mile.

This estimate is based on historical data

-contained in References 1 and 7.

Do these historical data pertain to severe storm conditions?

If not, are the esti-1 mates independent of whether storm conditions are present?

MP85 27/08~17-db a

^

Response

-The; United States Coast Guard is required by law to investi-gate all marine casualties in U.S. waters and any maritime casualty:world-wide involving a U.S. vessel of any kind.

This law requires a report-from the owner, master, agent, a person involved in a casualty..that resulted in damage in ex-cess of.$1,500,-material damage affecting the seaworthiness Lof1ef ficiency - of? a. vessel, grounding,. loss of life, or an injury.which incapacitates for more than 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> (46 CFR 74.05-1).

.The segment of the data contained in the Coast Guard files which deals with loss of power and steering for self-propelled vessels is for all weather conditions.

We have assumed that the. estimate A = 10-5/ mile obtained from

'the' Coast Guard ~ data. base is valid for all weather condi-i itions and would not increase in severe storms. The reason

~

for this is as follows.

The sub-surface currents and wind drag encountered by a vessel-during a severe storm would be somewhat jlarger. than under more " normal" deep sea storm cir-

'cumstances.for which the vessels are designed, but the stress on the power. screws and the rudder-(both under the

water level) would be so excessive as to cause failure.

The degree.of maneuverability available in terms of actual

~

headway possible in-the desired direction may be diminished but would not lead.to loss of both power and steering.

As such, we believe that a value for A of 10-5/ mile is appropriate.

Question 18 Explain why, once power and steering are lost, the vessel is more likely to head towards -the target :(rather thn equally likely.to move in.fany direction), by-a factor-of about 10 for the water-intake structure and.by a factor of about 100

~

for entering-the Hope Creek site (see page 47 of the ADL Report).

Response

.In1 order to achieve the extraordinarily high water levels p

associated with the various hurricanes, -the postulated 4

scenarios. require that-the hurricane follow a highly spe-z cific track.. The actual wind and current driven effects on

' a marine vessel would depend on the relative location of the vessel:with respect'to the " eye" or the center of the hur-ricane.

A drifting marine vessel' generally would move in a

-northern, direction with the wind and current,.but.could also

. drift;in an easterly or westerly direction.

Movement in'a H

southerly direction.isfnotspessible under-the postulated scenario.

LMP85.27/08 db.

+

The above situation was modeled.. analytically utilizing the appropriate probability distribution for wind and tracking of the vessel movement on a half-mile basis once the vessel was at'a location-within 10 miles south of the plant.

Based on this, and the ~ target size presented by the plant (120

ft. for the intake structure and 1500 ft. for the onsite safety-related structures), it was found that a drifting

-vessel was more'likely to move towards the plant than if the wind ~ direction was> uniformly distributed over 360*.

This l resulted -in a greater likelihood factor of 10 for the water intakei structure _and ' about 100 / for the Hope Creek site area

.of concern.-

Question 19 The probabilities of strike by a non-self-propelled vessel already within 10 miles of. Hope Creek striking the water in-take structure are stated on page 48 of the ADL Report to be 11.2 x 10-5 vessel for the intake structure.and 3.1 x 10-3/

~

/

-vessel for the Hope Creek site.

Were the same multiplica-

. tion-factors of 10 and 100 used in these estimates as the estimates discussed in item 5 above?

Response

Yes.

Refer: to'the answer to Ouestion 18 for details.

~

Ouestion 20 InL any --given-storm, wind speeds over water are higher than wind speeds over ground.

It appears. this _was not taken into account in the estimate of annual probabilities of.~ extreme six hour: wind speeds at-33 ft.; elevation.

Is this the

-case?L If-so,_why?

Response

To befpr'ovided=later.-

X

._Ouestion 21 In.the July 11984 MES Report.it is stated that the probabili-ty ofioccurrence in any one year.of a'" probable maximum hur-ricane," H(max), having a direction of motion D,Lcapable'of causing a.very large tidal esurge can be -obtained as follows:

7 :.

'P(H(max),D)..= P(H(max)) P(D) (1)'

~

?whereLP(H(max))'= probability.of_. occurrence in any one. year

'of a: probable maximum-hurricane regardless of trajectory,

-andLP(D) - probability of occurrence intany one' year of a C

l

'MP85.27/08.19-db' s

. n:c ~

1

\\

storm.having the direction of motion D.

It is estimated in the above-mentioned Report that P(H(max)) approximately equals 1000 per year.

It is further estimated in the Report that P(D) approximately equals 100 per year, the justifica-tion for that estimate being that only one storm in 100 years was sufficiently strong and had the direction of motion needed to cause a significant tidal surge.

Actually, P(D) should represent the ratio of the number of storms having a direction of motion D to the total number of storms, regardless of their direction.

For the area and time frame considered, it would follow from the report that this ratio is above 5/39 (page 9).

If the ratio 5/39 were used in equation 1 above, rather than the ratio 1/100, the

estimated probability P(H(max), D) would increase by an order of magnitude, i.e.,

it would be about 10E-4 per year, rather than 10E-5 per year as estimated in the MES Report.

To summarize, it appears that the MES Report uses, in lieu of P(D), a joint probability P(V,D),.where V is a relatively large wind speed such that P(V,D) approximately equal to 100 per year. -An explanation is requested concerning this matter.

Response-The NOAA document on the Standard Project Hurricane and the Possible Maximum Hurricane (PB80-117997) provides results that are deterministic in the sense'that each of.the hur-

.ricane parameters has been established as being possible for the latitude and the-coastline of concern.

However, this report only sets limits.to the-values that might be en-countered without providing any indication of the probabil-ity of occurrence.

For example, for Milepost 2400, the entrance to' Delaware Bay, the report shows that the forward.

speed.might range-from 40-80-km/hr (Fig. 2.7) and the angle of approach could fall between 70* and 185' (Fig. 2.9), but there is no indication what probability might.be associated with either of these ranges, or more important, what-their joint probability might be.

Furthermore, as pointed out in our earlier submittal on this subject, the authors of the PSH-PMH documents discourage the reader from; attempting to establish a probability for any of the individual-parameters, much less a probability for the-combination of the various factors.

MP85 27/08.20-db r

For'this reason, the original hurricane trajectory and intensity data was used in order to try to establish a reasonable probability of having the PHM affect the Hope Creek site in such a way as to cause the highest possible surge.

In that analysis, close attention was paid to the full trajectories of the storms, not merely the angle of attack and forward speed as they approached the coast.

To achieve the maximum ef fect, the storm could not pass over land for any considerable distance prior to reaching the site.

Neither could it follow any path to the east of the site or one more than a few miles to the west of the site.

It was concluded that seven storms passed within 100 miles west of the site between 1871 and 1983, but only one of these actually. followed a trajectory that would keep it over water until reaching the immediate site area (MES Report, 7/6/84, page 8).

In the earlier period analyzed, from 1683

-to 1869, it appears that five storms passed close enough to the west of the site to produce reportable storm surges, but only one seems to have resulted in a major flooding of the area (ibid.-page 9).

A hurricane would have to follow a trajectory taking it past the site within approximately a 10 mile band to be included in an analysis of the probability of having the PMH cause a major surge in the area.

Based on our assessment, we conclude that the probability of the'PMH surge.is a combination of having the PMH aggregation of parameters occur simultaneously ( 10-4) times the proba-bility that the storm would approach the coast on precisely the right trajectory and pass cases in 300 years, or <10-2).just west of the site (two The 5/39 ratio cited in question 21 is certainly not. applicable, nor would it be proper to use seven over the total number of hurricanes ob-served in the 1871-1983 period.

Question 22 It is stated in the August 1984 MES Report (page 4) that the NBS BSS-124 document "is based on actual hurricane clima-tology and statistics only insofar as the frequency of oc-currence of hurricanes in various locations is concerned."

Actually, NBS BSS-124 also uses statistics based on climato-

-logical data concerning the pressure' dif ference between center and' periphery of storms,' radius of maximum wind speeds, speed of translation of storm, and direction of storm translation (see pages.3 and 4 of NBS BSS-12).

The MCS Report should be corrected to reflect this information.

MPSS 27/08 21-db

V

Response

NBS-124 was based in:part on climatology other than just the frequency of occurrence.

However, the misstatement has no ef fect1on the utilization of the data in the report, nor does it have.any bearing on the new estimates of fastest-mile ~and longer-period wind data.

Question 23 In Table 1 of the August 1984 MES Report, were any of the storms of the thunderstorm type?

This question is asked be-cause if indeed some of those storms were of that type, then the ratios, FM/lH and FM/6H, would be too high to be pos-sibly representative of hurricane winds."

Response

The events listed in Table 1 of the August MES Report are the dates of the maximum annual six hour wind speed averages for each of the 11 years of record.

These events do not necessarily contain the overall maximum fastest-mile wind

-speeds for each.of these 11 years, and it is probable that some of the absolute fastest-mile observations may have been associated with thunderstorms.

However, review of the synoptic situations for each of the time periods used in the analysis indicated that in all cases the strong onshore winds were caused either by deep winter-type low pressure systems located west of the site, or_a combination of strong high pressure to the east and low pressure to the west.

These situations indicate strong winds persisting for time periods on the order of hours, not minutes as is common with thunderstorms, and there was no indication that thunderstorms contributed to any of the fastest-mile. data.

.Th'e re f ore, the' ratios of fastest-mile wind speeds to longer-term averages quoted in the MES Report are representative of larger-scale storms.

The method of~using peak / average ratios based upon non-tropical storms to simulate hurricane situations is recommended.on page 10 of the NBS-124 document.

-Question 24 Page'7 of the August 1984 MES Report reproduces estimates of

~

directional fastest-mile wind speeds from the NBS BSS-124 Report.

However, the estimates of NBS BSS-124 pertains to

.MP85 27/08 22-db

TT A-winds blo' wing from a 360*/16 = 22.5* sector, rather than "from/the.79*-170' sector.

Using data on which the NBS BSS-124 Report _ is based (which are available on tape at I NBS), the fastest-mile wind speeds at 33 feet over ground is festimated,as 36 mph, 73. mph, and 85 mph for the 10, 50, and 100 year means recurrence intervals, respectively, rather than_24 mph,.57 mph, and 70 mph, as indicated on page 7 of thefAugust 19841MES Report.

. Response

-To be provided.later.

Ouestion 25

~

Page 4 of the Arthur D. Little, Inc. report, "An Analysis of the Likelihood of Waterborne Traffic and Other Floating Ob-jects on the Delaware River Impacting the Hope Creek Gen-ferating Station in Severe Storms" revised report dated

~

September 1984,. lists a number of floating objects such as

~

. utility poles,7 houses, automobiles, fuel tanks, and trees (which were analyzed.for. potential damage to metal doors in Lthe' power block.

In view of the location of rail lines and chemical -industries at relatively low-grade elevations up-

~

stream from the: reactor site, indicate if empty railroad tank cars-and industrial chemical storage and/or processing tanks.should also be included in the flood missile spec-trum.~

' Indicate the size (and mass) of these-tanks as com-

= pared with the ' size aof the power block. doors and hatches.

Response-

~

As indicated in answer to' Question 1, the highest water levels associated with flooding events initiated from the north-are those associated with the seismic multiple dam.

failure combined.with the one-half PMF event on the. entire river basin and the 10. percent excedence high tide-at the-plant site.- This event leads to a site water level of 11.4 ft."above'Mean Sea Level'.

Under these conditions, the. water

' level would be~about 1~ft. below plant grade.

As such, any

= waterborne missileHgenerated north of the plant could not:

exist on plant grade and could not impact.the power block

. doors and: hatches.

e-;[ +

h 4

.2 MP85 27/08123-db-

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