ML20235G815

From kanterella
Jump to navigation Jump to search
Revised Nuclear Safety-Related Moderate Energy Line Break Flooding Evaluation Rept Sequoyah Nuclear Plant Units 1 & 2
ML20235G815
Person / Time
Site: Sequoyah  Tennessee Valley Authority icon.png
Issue date: 03/06/1987
From:
SARGENT & LUNDY, INC.
To:
Shared Package
ML20235G786 List:
References
SL-4424, NUDOCS 8707140390
Download: ML20235G815 (53)


Text

,.

e w 34 o

-... -. ~.

- ~.. -.

2 u

. n~.

.....~ -

.A suns v,. '. c.

e.

. n.

~

. v_>. an

. a

.w 4 e.-

.~ --

=

._.- ~. _

_.. ~..

I_~S'Ocidir~5alst9-hsihted 1 ~

f

... ~.,

- Moderate Energytirte Break--

Floodini Sh~E. DEI.N..iic.l.iarf t:vE1DstidrfRepdPt' ~

~~~

P.ii.h..f.~0.n..i.is T...and.s~. ~..

j si

(

Tennessee. Valley Authority -.

.. R. epon. SL.-4424 August 29,1986 R..e.v.ise.d De..c. em.b 3.r_12,1986 _.._.._

. --...-... R. e.vis..e. d. Mar.ch. _6, 19_87.._

--^

~

e-6.

'6 NW6 GP ".G+h1b.SA....e+*.

,pm

...u.-

.ai.gh wh.

.. egg h

, e m D

Ib.h. W e.e.ge esp.pauppio.g de eg.a

.qqg, gap,,,,g,,,

,g,,

' " ~ ~ ~ ~ ~ ~ ~ ~ ~

G707140390 870702 PDR ADOCK 05000327 P

PDR

'~

^

' ' ~

~

9Cr>4 1

~

D3-67-398 4

W.

a.s 8

__,.,,,._A o

1 l

1 u.N i

i l

1 I

l 1

Date: 03-06-37 I

... _ _.. Issue Summary of SL-4424 l

~

q Date P --

Revision Date.....

Pace __..

Revision

-. a n- - - - ~-~

~

"J~"

~51~~

~~

_. -.. - _.ES _ 1.....

2.

03.06 - --. _... _.... ' -.2

~

03-06-87 '

]

ES-2..

1 12.86 72 2

03-06-87 g,g p - - 7_3-. _ _-_. --.. - 2~-

~ 03-06-S7-1..

12-12-S6.-

g...._

12-12 8 6 -- - ~ S-1...... - -

.T'rI ' '~ ~ ' ~~~~ ~ t'~ ^ ~ 12 8 6-- -

8 - --

---1

-. -.12-12-86

..___.. 2

--- ----- - --- 12-86. ~. 8-3.,... _

1 -

.12-12-86 2-1 1

12-12-86 8-4 2

03-06-87

. _ i. -.._. --l 12-8 6 - 5 ---- -.

12.-12-86.-

. _... _g -

2-3 1

12-12-86 Appendix A 1

. 2.

12-03-86

-.--- 2 -. -... - -l..

.~.12-12-8 6_.__

...,-. 23.

, l.. _.

.12-12-86..

_. 2,,. _

2 _ _,,,

12-03-86 1..

_....-12-12..8 6......

3 2

12-03-86 3-1 2

12-03-86 7-.

. 12:12;86-~ '

5'

~

2 12-03-86 3.q___- _..--.-..__ 7.__ _.--12-12 -

6- - -

. 2 - 03-86

-.- g. 2 -- -- - -- - --- 1 -- - -

12-12-86 7

- 2

.12-03-86 L. e : =..._ 2.

I 2-03-8 6 3;_3 j

..-12_l2-36 9_- -

-.. 03-86

-..._, _ 3.t m.__.1.~... _.12-12-S6. -..

.;2-.

12-03-86

_.-.5-2..._..-_.-..

. 1

..__..12-12-86.._..

10 ; _.

2 12-03-86 03:0'6 '

12-2 12-03-86 p.

12-12-86 13-2 12-03-86 6-4 1

12-12-86 14 2

12-03-86

.._._.6'-5~

~

' ' ~^~

1-17-12.

15 2

12-03-86

. 16 2

12-03-86 (7e n.w.3,

2..,.. n,, 12.03-8 6 w*.

...d.

.g m,4 g.e...-...

n'M'

  • be w

p.,

C

=

.6

+6--

b.

._.-4..

W.a.

NJ.-

.e.ieg..,,

e.s b

ap..i.

s.-

O g<,.ecN.*

.a.-W

-.po.e q_-

W.m

.m.

e4'hi.-

z w 24 SARGENT & LUNDY ES-1 SL-4424 08-29-86 Rev.12-12-86 Rev. 03-06 _87

. w..

_. EXECUTIVE S_UMMARY nevrs.

~

This report has been developed'to provide an organized overview of work performed by Sargent & Lundy to evaluate moderate energy line break (MELB) flooding events for the Tennessee Valley Authority (TVA) Sequoyah Nuclear Plant (SQN). The actual work performed is documented in calculations incorporated by reference into this report (see Section 8).

These calculations have been provided to TVA under separate cover.

This work was i

performed at the request'of. the TVA Nuclear Engineering Branch in Knoxville, Tennessee.

This MELB flooding evaluation serves to verify previous design work done by TVA and is based on the as constructed plant status, it also provides comprehensive documentation that demonstrates adequate plant design for MELB flooding events.

Certain followup actions are required of TVA to ensure that the assumptions used in the analysis are valid. These are:

Modify TVA Test Procedure SL-129 Flood protect the turbine building "n"-line wall to elevation 706 feet 0 inches Document certain high pressure fire protection (HPFP) lines as equivalent to Seismic Category !(L) Pressure Boundar.y Retention Flood prctect certain safe shutdown cables and non-safe shutdown cables exposed to borated water flooding Provide structural qualification of floors in certain flood zones Modify certain shutdown board main circuit breaker trip settings and sensor sizes Modify drainage in the reactor building annulus Provide documentation of crack exclusion for the test return header to the

+

refueling water storage tank and certain component cooling water piping Spurious operation of associated equipment that might prevent safe shutdown was not evaluated in this report R

The effect of degraded bus voltage due to MELB flooding was not evaluated in this report i

j

.A

v e 34.

i SARGENT 5 LUNDY ES-2 SL-4424 08-29-86 Rev.12-12-86 Sargent & Lundy recommends that these actions should be summarized by TVA tnrough issuance of a.TVA calculation, "MELB Flooding - Summary 'of Corrective Actions,"

SQN-SQ54-59.

= "

L L

ce-3 9 4' '

y

'SARGENT & LUNDY i-L.u.L..;.

SL-4424 08-29-86 Rev.12-12-86

~

.~n---..-

CONTENTS

. a.-: e

_r-r+r r.

i'--

- ~~~: '

Section Pace EXECUTIVE

SUMMARY

ES-1

'1 INTRODUCTION 1-1 2

DEFINITIONS 2-1 3

METHODOLOGY 3-1 General 31 TVA input Documents 3-2 Field Verification 3-2 4

SUMMARY

OF FLOOD LiiVEL CALCULATIONS 4-1 General 4-1 Detection and Isolation 4-1 TVA Crack Exclusion 4-2 Unverified Assumptions 4-2 3

SUMMARY

OF STRUCTURAL FLOOD LOAD ASSESSMENT 3-1 Unverified Assumptions 3-2 6

SUMMARY

OF SAFE SHUTDOWN ANALYSES 6-1 Safe Shutdown Evaluation 6-1 Safe Shutdown Power Supply Analysis 6-1

' Unverified Assumptions 6-2 Cable Submergence Analysis 6-3 7

CONCLUSIONS AND RECOMMENDATIONS 7-1 Program Followup 7-2 8

REFERENCES S-1 APPENDIX A

Sargent & Lundy Project Instruction PI-SQ-05, " Evaluation of the Effects of MELB Flooding Inside and Outside Containment"

c c.c N j

.SARGENT & LUNDY 11 SL-4424 08-29-86 Rev.12-12-86

)

l 1

EXHIBITS l

i Exhibit

)

3-1 Workflow and Documentation Used to Support the MELB Flooding Evaluation j

l I

i 1

1 l

i i

l I

7ef M w

.SARGENT & LUNDY l-1 i

SL-4424 1

08-29-86 Project 7659-00 Rev.12-12-86 Section 1 INTRODUCTION I

This report summarizes work. performed by. Sargent & Lundy to evaluate MELB flooding.

events for the Sequoyah Nuclear Plant (SQN). This report also serves as a guide that shows the relationships among the various design documents produced as a result of this evaluation. The process and controls used to perform this evaluation are also discussed.

Code of Federal Regulations 10 CFR 50, Appendix A, General Design Criteria 4, requires that structures, systems, and components important to safety shall be designed to accommodate the effects of and be compatible with the environmental conditions associated with postulated piping failures. The effects of postulated piping failures include fluid jets, sprays, and pipe whips, while the environmental conditions include pressure, temperature, humidity, radiation, and submergence. The effects of fluid jets, sprays, and pipe whips are addressed in the TVA CEB Pipe Break Reports.1,2 The impact of environmental conditions associated with piping failures including pressure, temperature, humidity, raoiation, and certain aspects of submergence (e.g., high energy line break (HELB) flooding 3 ~and submergence inside the reactor building) is coyered by the TVA Equipment Qualification Project for Sequoyah. MELB flooding issues, including structural loading and submergence, are addressed in this report.

Historically, flood protection at SQN has been provided by plant design features and sup-ported by engineering evaluations. One design feature is the large passive sump in the-auxiliary building. In general, this sump gready increases the margin for operator response in detecting and isolating ficoding sources. Additional design features include the use of com-partmentalization, dropout panels, hatches, open grating, and curbs. Engineering evaluations were performed by TVA as required. However, these evaluations were not comprehensively documented in all cases. This MELB flooding evaluation serves to verify previous design i

r I

(

y os: 24 SAEGEN't & LUNDY l-2 SL4424 08-29-86 Rev.12-12-86 2

i work done by.TVA and is based on the as constructed plant status and also provides com-prehensive ' documentation that demonstrates adequate plant design for MELB flooding events..

. Sarge:nt & Lendy based evaluations on TVA <focuments provided by TVA. Sargent '& Lundy did not independently verify the contents or accuracy of these documents. Field verification of j

certain information was carried out by Sargent & Lundy, including confirmation of drainage path parameters and submergence levels of Class lE electrical equipment. Various verbal and written directions were provided by cognizant technical personnel at TVA, and this-direction is documented in Sargent & Lundy calculations and TVA Quality Information Requests.

R

/

l

. - ~ -

F err J 9 l

i~>

SARGENT 5 LUNDY 2-1 SL-4424 08-29-86 1

Rev.12-12-86 4

l 1

1 i

.i

%.M

  • 1I*'
i.
  • C h h #.,

2'

,.; 3 h

..b'

'I,..

. ce

$.,- :.:;ne nn -

-.ra.

e m: DEFINITIONS - -

DIIe... _,,e. au e. v.wu,:. -

. - cc:,rc 7.

Sargent:& Lbridy's design inforniation trarismittal process and standard form.

DCL~L"" F'-

- :~"

.' c.....

Sargent & Lundy's document controi log for use of TVA documents.16'17'18'19 ERCW Essential raw cooling water system.

i ESSENTIAL STRUCTURES, SYSTEMS, AND COMPONENTS Structures, systems, and components recuired to shutdown' the reactor and mitir, ate the consequences of a postulated piping failure, including systems and components regoired to detect and isolate postulated piping failures. Essential structures, systems, and components are required by TVA to be Seismic Category I.

HELB High energy line break. This represents the event of a postulated circumferential rupture of a high energy fluid system line.

HIGH ENERGY FLUID SYSTEMS r

Fluid systems that, during normal plant conditions, are either in operation or maintained pressurized under conditions where the maximum operating temperature exceeds 200*F. This criterion reflects the actual TVA criterion applied in evaluating the effects of flooding due to high energy line breaks. High energy lines are not within the scope of the MELB flooding study.

e.~~~

m as-z4

.u.

1 SARGENT & LUNgy 2-2 1

SL-4424 03-29-86 Rev.12-12-86 I

HPFP-i 1'

' High pressure fire protection system.

.MELB Moderate energy line break. This represents the event of a postulated thro,agh-wall leakage crack in a moderate energy fluid system line.

MCC Motor control center'.

MODERATE ENERGY FLUID SYSTFJAS FNid systems that during normal plant conditions are either in operat..on or maintained

. pressurized (above atmospheric pressure) under conditions where the maximum operating

. temperature is 200*F or less.

NORMAL PLANT CONDITIONS Plant operating conditions during operation at power, reactor startup, refueling, testing, hot standby, or reactor cooldown to cold shutdown condition.

POSTULATED PIPING FAILURES Through-wall leakage cracks postulated according to the provisionsr/of Sargent & Lundy Project instruction PI-SQ-05.9 PRIMARY SAFETY FUNCTION The passive or active function of a structure, system, or component that must rernain I

functional to assure directly 1) the integrity of the reactor coolant pressure boundary (RCPB), 2) the capability to shut down the reactor and maintain it in a safe shutdown

(

// or 34 SARGENT E LUNDy 2-3 SL-4424 08-29-86 Rev.12-12-86 condition, or 3) the capability to prevent or mitigate the consequences of accidents that could result in potential offsite exposures in excess of the guideline exposure of Code of Federal Regulations 10 CFR 100.

.m.

SAFE SHUTDOWN

.Thego.nditiog.under which all required saf.ety functions, including reactor criticality control, primary an,d secondary inventory and pressure control, decay heat removal, and environ-mental control are being achieved and maintained within design limits.

SAFETY-RELATED i

Those plant features that perform either a primary safety function or a secondary safety IU*C'$"* ~.

t SARGENT 5t LUNDYDIVISIONS 2

EPED - Electrical Projec: Engineering Division MDDD - Mechanical Design & Draf ting Division NSLD - Nuclear Safeguards & Licensing Division SED - htru'ctural Engineering Division SEC0NDARY SAFETY FUNCTION The function of a portion of a structure, system, or component that must retain limited structural-integrity because its failure could jeopardize, to an unacceptable extent, the achievement of a primary safety function or because it forms interface between Seismic Category I and Seismic Category !(L) or nonseismic plant features.

w, -

/2 aC 34 SARGENT & LUNDY 2-4 SL-4424 08-29-86 Rev.12-12-86 SEISMIC CATEGORY I The designation of those structures, systems, or components that perform primary safety functions and that are designed and constructed so as to assure achievement of their primary safety functions at all times including during a concurrent safe shutdown earthquake (SSE).

SEISMIC CATEGORY I(L)

The TVA designation for those structures, systems, or components that perform secondary safety functions and that are designed and constructed so as to assure achievement oLtheir secondary safety functions at all times including during a concurrent SSE.

SE5MIC CATEGORY I(L) PRESSURE BOUNDARY RETENTION The TVA designation for those structures, systems, or components that in addition to being classified as Seismic Category 1(L) are designed and constructed so as to retain fully intact their pressure boundary at all times including during a concurrent SSE.

SINGLE ACTIVE COMPONENT FAILURE The failure of an active component to complete its intended function upon demand. It is the loss of function of a component of an electrical, mechanical, or fluid system. The failure of an active component of a fluid system is considered to be the failure of a component to l

perform its function as a result of mechanical, hydraulic, pneumatic, or electrical malfunction, but not the loss of component structural integrity. The direct consequences of a single active failure are evaluated.

(A single active failure is postulated to occur simultaneously with the postulated pipe failure, passive failures are not postulated). Where appropriate, the dual purpose moderate energy exclusion, as described in Section 5.2 of R

Appendix A, is utilized.

i

\\

l l

/s on.74 -

4

.SARGENT & LUNDY 2 un m,,,.

SL-4424 08-29-86 Rev.12-12-86

.~....

/-

.THROUGH-WALL LEAKAGE CRACK

= a.v....

.The_ postulated failure mode of a moderate energy:c.luid system line. Fluid flow from a f

. u a.a.. : ;

.:1s v. ::.:.,

..s:.

. :: c.

.. rough-wall lea.kage crack is based on a circular opening with an area equal to an equivalent th

.e.

e v := m e. 2

= c.:.... '. =.... :.. x. - :

rectangular. opening of one-half,th. e p.ipe inside. diameter in length and one-half pipe wall

~...

thickness in width.

s : :,..

3;.,.

  • :W 3 * % :4 '.~.:.'.'.'

e

~:

-,.u.-.~.w..

i

.- ;. a :.~.....

I,iti..t1 '...... ",.

l

. g ;,

l

.. ~ ~ '

1... ?. T.e c...

.~.

l.

LD Y :'

.k :

--~

l I

w

.s.w w -.

MwM

. SARGENT & LUNDY

}- t -

SL4424 08-29-86 Rev.12-12-86 Section 3 METHODOLOGY

. GMNERAL

' The goal of this study is to demonstrate that safe plant shutdown can be achieved for design basis MELB f, boding events. This requires both a structural load assessment and an electrical equipment safe shutdown evaluation. These in turn require input on flood levels arising from postulated i.iELB flooding events. The major elements of this stuoy were Flood level calculations (including field verification of input parameters)

Structural load assessment Safe shutdown evaluation (including field identification of submerged Class iE electrical equipment)

Safe shutdown power supply analysis Cable submergence analysis Exhibit 3-1 shows the relationships among the tasks required to perform this overall evaluation.

These tasks are further described in a series of Sargent & Lundy Project instructions, PI-SQ-04, -05, and -06.8,9,10 "MELB Flood Level Calculations"ll provides flood levels for postulated MELB flooding l

events for input to structural flood load arid safe shutdown assessments. These ca.tculations I

are summarized in Section 4.

" Structural Flood Load Assessment"12 verifies structural adequacy by comparing design basis MELB flood loads to allowable floor live loads provided by TVA and to concrete and masonry wall capacities calculated by Sargent & Lundy.

This assessment is further described in Section 5.

6

/S~ e:f.34 SARGENT & LUNDy 3-2 SL-4424 08-29-86 Rev.12-12-86 The safe shutdown evaluation was divided into three parts.

"MELB ' Safe Shutdown Analysis"I3 examines safe shutdown for'MELB flooding events in which Class IE electrical

. equipment was' found to be submerged based on field walkdowns.I4 This analysis assumes that safe shutdown power supplies and submerged cables that are required will be operable during the MELB flooding event. This is ensured by two analyses presented in Section 6.

The design criteria used to perform the various evaluations of this study are contained in the

, Sargent & Lundy Project Instruction PI-SO-05,."Eva!uation of the Effects of MELB Flooding inside and Outside Containment."9 This document is included as Appendix A to this report.

~

I Specific modeling assumptions used to perform various analyses are documented in individual calculations.11,12,13,15 TVA INFUT DOCUMENTS A number of TVA documents, including drawings, diagrams, calculations, design criteria, letters, memoranda, surveillance ' instructions, general operating instructions, system operating instructions, and reports, were used as input to the various MELB flooding analyses.

Use of these documents is controlled by Sargent & Lundy Project Instruction PI-SQ-17, " Project Instruction for Use and Control of TVA Drawings and Documents for L

Sequoyah Flooding Study."16 The TVA documents used by Sargent & Lundy are recorded on three separate document control logs, one each for EPED, NSLD, and SED.I7'I8'I9 in addition, cognizant technical personnel at TVA provided verbal direction and interpretations, which in turn were documented by Sargent & Lundy.

FIELD VERIFICATION

. Field verification of various input parameters used to calculate flood levels was performed by the Sargent & Lundy walkdown team unoer Sargent & Lundy Project Instruction PI-5Q-06.10.This team also performed submergence walkdowns for electrical equipment, based o MELB flood levels, under the same project instruction.

l:

i


,----,-----.,--,--.--.----------,---,_m 0

4 V

. ap # E *-

~

g I

O

  • 4f '*

~ ~ p !, u:.

g*e j

N f m

1'

.sa.

g' 1 wnoz

,{

j d'

4 g

e f i ep ;;8 i

?.1 I

L i

l

- m s e. e :.

.:E,

- ! I.

P ; ;

3 if

I-ge i

5 8

), ;I k

5 g

3

=

l h

$ [

I

  • l (1} I i l 1

{

s

'lp;s:

i. f 3

x r

2 g

2 3

a F =i.l i f i.}. i.

E

.:y1 2

t s

e 9

e ess r

=

w 4-9 91 O

w 8

s 4

i{ s t

S

i.. -

I s

II alI s

i r

+

d

.i l E'

{43 uk2 i

5 kN#

"I' E j g

5 36 5 *I i

=

c

  • o, o

g s =

I!$

k N.

I 1

'l

=23 h!4 R

,a. g :. -

}

T i

9

" 3.i 1(

d o

1

  • 1
  • ] a.

o u B.w B32 i i I

e, g

3 d i.

}i 8

J'**

4 jf l

3,.

n

{g t

O g

}

stu:

3 i

at 3

3 t

{ e n,g d.

o aP o

- G s*

.o 3*=

-.g

  • IEW.

g s

g g

uf}

g 983.9 E

Xg g

sa u

L y

M 2

~

er 3b

<a

~

/ 7ac.74 SARGENT8 LUNDY 4-1 SL-4424 08-29 '

Rev.12-12-36

'~

Section 4

SUMMARY

OF FLOOD LEVEL CALCULATIONS

. GENERAL Flood levels are documented in "MELB Flood Level Calculations."II Methods and

'assumpSons used in 'this calculation are based on criteria contained in Sargent & Lundy 9

Project.Instruedc.. PI-SQ-05 and are fully documented as part of the calculation. report.

Two important modeling assumptions used in the analysis were that only one piping failure was assumed for each MELB event and that no credit was taken for flow into floor drains.

The flood level calculation examined flooding events in 250 flood zones in the auxiliary, R

control, diesel-generator, and reactor buildings and in the ERCW pumping station. Many flood zones experience flood levels of less than two inches because available drainage pathways prevent appreciable accumulation. Other zones act as sealed compartments and experience higher levels.

Flood zones, sources, drainage pathways, and levels are comprehensively tabulated in the calculation report.II Two flood levels were calculated for each ficod zone; one for flooding sources originating within the zone (h ) and one for flooding sourccs originating outside of the zone (h ). These 3

2 flood levels were used in the structural load and safe shutdown assessments. While no credit is taken for flow into floor drains when calculating h g flood levels, the potential for limiting p

2 flood levels due to backflow through floor drains was evaluated. This type of flow was h

found to produce limiting h2 flood levels for about 10% of the zones.

DETECTION AND ISOLATION The duration of fluid inflow from a postulated MELB was generally taken as sixty minutes.

R This incluoes time for both detection and isolation. This inflow time is significantly longer than for HELS events because of the general unavailability of automatic isolation for moderate energy systems.

/7 cA~34 SARGENT S LUNDY ~

4-2

{

SL-4424 l

08-29-86 i

Rev.12-12-86

]

Detection is assumed to be provided by a combination of means including roving watches by plant and security personnel, personnel at permanent watch stations (e.g., Zone 669.0-Al),

non-safety related flood and sump level alarms, and system performance indicators sucn as low flow or surge tank level.

The assumed act;ons and times required to isolate leaking fluid systems are documented in a separate calculation, " System Isolation for MELB Flooding."20 This calculation describes the actions required to isolate leaking systems, including the necessary. actions to establish alternate trains where required.

For most zones (approximately 80%), calculated flood levels are independent of the assumed inflow duration..The levels reported for these zones are steady-state levels where inflow is balanced by outflow. The use of steady-state flood leveis generally simplifies the analysis

- without introducing excessive conservatism into the calculated results.

TVA CRACK EXCLUSION Stress levels in certain moderate energy lines allow use of the crack exclusion criteria to eliminate postulated piping failures in these lines. These criteria are set forth in the NRC Standard Review Plan.22 These lines are tabulated in the flood level calculation,II and crack exclusion hr.s been documented in separate calculations by TVA.II UNVERIFIED ASSUMPTIONS Certain assumptions used in the MELB flooding study remain unverified at the time of this II report. These are listed in the MELB flood level calculation and are 1

It has been assumed that the study performed by Earthquake Engineering will demonstrate the HPFP piping in Zones 749.0-A6, 749.0-A7, 749.0-A10, and 749.0-All will not fail under design basis earthquake conditions.

The wall from the turbine building to control and auxiliary buildings is assumed to be flood protected to elevation 706 feet 0 inches.

m

n' or 34 SARGENT 8 LUNDY 4-3 ht' SL-4424 c

08-29-86 Rev.12-12-86 l

l Doors to both the A and B train safety injection pump cubicles are assumed to be open. during, period.c. functional testing of either pump in the SI

_ + ::

3 system. This requirement is not currentiv a,part of the test procedure.

l r an: 3e:cr.. :e 3:nr:e. r~nm

. a'-

-,- ::q Flooding.in the reactor building annulus is limited to~2 inches by assuming free flow, in the emergency drain system, which is prevented by a normally

' closed valve. Verification of this assumption requires that TVA modify or upgrade detection and isolation capability for line breaks inside the annulus or modify the flow path from the annulus sump.

R a assu zr.e-r-

. :.5: -

. Thectest. return header to the refueling water storage tank and certain

~~~

Tornpon'ent' cooling system piping in' Zonas 714.0-A7 and 714.0-A3 are assumed to meet the crack exclusion criteria.

+-

c...t-L 1-

'- =i.

O L,i" L '.* :

I '. : : -

:. t :-

..' 7

. rt :

.e.

O t ?'..

""'"f-

.?

. ~11.

L;:....

.4

.'i,'

I\\..

... u.

1

.4 Ed-

.n.--

na

=m

=-

l 4

...-...ul

c ze a - 3+

SARGENT & LUNDY 5-I-SL-4424 08-29-86 Rev.12-12-86 Section 5

SUMMARY

OF STRUCTURAL FLOOD LOAD ASSESSMENT The structural assessment for flood loads due to postulated MELB flooo.

events is documented in SED Calculation Book No. SF4P-01, Revision 3.12 A total of 250 flood zones R

throughout the auxiliary, control, diesel-generator, and reactor buildings and the ERCW

. pumping station were reviewed and found to be structurally adequate.*

The structural assessment included a review of the affected slabs, beams, columns, and walls for each flood zone. The qualification of the slabs, beams, and columns was based on a comparison of postulated flood loads to the allowable floor live loads provided by TVA on Drawing 41N704-1, Revision 6, and TVA Letter No. B41-860709-001. Walls were qualified based on a comparison of postulated flood levels to the wall capacities that were generated by Sargent & Lundy. Per the above method, each structural element in each flood zone was

. R shown to be qualified for flood loading due to postulated MELB flooding events.**

Calculations verifying these conclusions are filed under TVA Branch / Project identification No. ' SCG-IS69, SED Calculation Book No. SF-OP-01.12 This calculation consists of six R

sections.

Section 1 includes the design criteria and control documentation for the calculations. Section 2 consists of the generic calculation of wall capacities used in the qualification of walls in Sections 5 and 6. Section 3 is a compilation of pertinent design input documents and references required to support the design basis of this calculation. Sections 4 through 6 comprise the detailed assessment and qualification of structural elements for each flood zone.

TVA is responsible for providing structural qualification of the floors located in flood

ones 669.0-A15, 669.0-A16, 714.0-A7, calculation 3C37-0686-001, Revision 3.gnd 714.0-A8 for the flood levels listed in NSLD R

Exceptions to this are flood zones 690.0-All, 690.0-Al2, 690.0-A15, 690.0-A16, 714.0-A6, and 714.0-A10, which have been structurally qualified by TVA per QlR Number SQPS6132 dated November 5,1986.

2/a= 34 SARGENT & LUNDY 5-2 SL-4424 CE-29-86 Rev.12-12-86 l

UNVERIFIED ASSUMPTIONS Certain assumptions used in the MELB study remain unverified at the tirne cf this report.

These are:

R-Verification of the adequacy of the walls and slabs for Zones 669.0-A15, 669.0-A16, 714.0-A7, and 714.0-A8.

)

w 22 w r4 4

' SARGENT & LUNDY 6-1 SL-4424 08-29-86 Rev.12-12-86 Section 6

SUMMARY

OF SAFE SHUTDOWN ANALYSES SAFE SHUTDOWN EVALUATION The'"MELB Safe Shutdown Analysis"I3 documents the evaluation of the ability to achieve safe shutdown for MELB flooding events. This evaluation assumes that safe shutdown power supplies and cables that are required will be operable during the MELB flooding event. This assumption is ensured through analyses discussed later in this Section.

The safe shutdown evaluation examined MELB flooding on a zone by zone' basis Field 10,14,7a were used to identify Class IE electrical equipment that was submerged walkdowns by the calculated MELB flood levels. When essential equipnient was found to be submerged based on field walkdowns, the ability to achieve safe shutdown was evaluated for flooding events that could submerge that equipment. Other Class IE electrical equipment that could be submerged concurrently was also considered.

The list of available safe shutdown equipment was taken as that provided in the Appendix C list from the TVA document

" Equipment Required for Safe Shutdown per 10 CFR 50 Appendix R."5 This list was supplemented by Sargent & Lundy with the components necessary for operation of the safety i

injection system. Required system controls and instrumentation were examined through use of block diagrams.5 The r.bility to achieve safe shutdown was demonstrated for the j

postulated MELB flooding events with consideration of single active failure and loss-of-offsite-power. The flooding effects of nonseismic pipe breaks on safe shutdown equipment were also evaluated. Details of these evaluations, including methodology and assumptions, are documented in the safe shutdown analysis calculation.I3 SAFE SHUTDOWN POWER SUPPLY ANALYSIS l

i Auxiliary Power Systems The evaluation of the ability to achieve safe shutdown included an assessment of the j

auxiliary power system to ensure the availability of required shutdown boards during flooding

V 23 w21 4

l SARGENT& LUNDy 6-2 j

SL-4424 08-29-86 Rev.12-12-86 Rev. 03-06-87 events.

Specifically, the objective.of this assessment was to evaluate increased board loading due to submergence of equipment and to determine if the increased loading could be sufficient to trip the main breaker. Main breaker trip renders a safe shutdown board unable to power safe shutdown loads.

l During the course of this review, it was found that several main. circuit breakers were inadequately selected and/or set with respect to their ability to carry normal worst-case continuous current, irrespective of any flooding conditions. Recommendations for corrective action to resolve this problem have been developed and are included in the " Safe Shutdown l

Power Supply Analysis.15 Assuming implementation of tne above-noted recommendations for corrective action, the

" Auxiliary Power ' Systems Analysis" demonstrates the avaliability of required shutdown boards during M,ELB flooding events.

UNVERIFIED ASSUMPTIONS Certain assumptions used in the MELB flooding study remain unverified at the time of this report. These are:

Verify that flood protection for certain conduits containing safe shutdown cables and ncn-safe shutdown cables exposed to borated water flooding are sealed or qualified for the submergence.

Verify that certain shutdown board main circuit breaker trip settings and sensor sizes are modified.

Spurious operation of associated equipment that might prevent safe shutdown was not evaluated in this report.

The effect of degraded bus voltage due to MELB flooding was not addressed in this report.

R Control Power System As part of the overali evaluation of the ability to achieve safe shutdown, control power systems were assessed to ensure the availability of required systems during ficoding events.

Specifically, control power systems required for safe shutdown were assessed for the effects

24 # 34 S A.R.. GENT. & LUNDY 6-3 n...

SL-4424 08'29-86 Rev.12-12-86 obdact. eased loading::resulting -frorn :ftooding of control circuits b' th-at component and o

exposed' intermedia te; terminations.

r. e a 1 The methodology used in the Sargent & Lundy assessment of control power systems was to

.showethat the 'fVA Calculation SQN-SMBC-li Revision 16 for in-contairiment submergence due-.to: postulated tfELB flooding of control circuits, which documents acceptable results, represents armore severe challenge to the availability of control ~ power system' ~ thEn does

~

s

_(

postulated 'MELB-induced flooding.

Once this is demonstrated, no additional detailed calculations to address control power systems under MELB flooding conditions need be prepared.

.-._nc_

As-in the~ auxiliary power study; the concern is flooded, non-safe shutdown equipment inat could potentially disable required shutdown boards. Control circuit loads required to achieve safe shutdown are, by definition, not submerged, since submergence is assumed to render circu'idiinopirable..

x x asr.- uc u.

~

' Based on the assurnptions and evaluations included in the " Safe Shutdown Power Supply Analysis,"I0 the effect of MELB flood waters on the control power systems will be less severe tha(the, effects. analyzed;iri TVA. Calculation No. SQN-SMBG-1, Revision 1,6 which were found by TVA to be acceptable.

CABLE SUBMERGENCE ANALYSIS General ve -. rr "

Numerous types of cables are installed at SQN.

The compilation of existing cable documentation to' demonstrated qu'alification for submergence was not within the scope of the present study. Therefore, an a! ternate approach was used: either it was demonstrated that cablp_are not submerged as a result of postulated MELB flooding, or safe shutdown cables that potentially may become submerged were indicated as requiring flood protection.

e.-.m=*

tw

_weeuqqu

l

}

2sof 24 SARGENT & LUNDY:

6-4 SL-4424 i

08-29-86 j

Rev.12-12-86 l

1 l

l Cables in Cable Trays i

As a result of postulated MELS flooding, cables may become submerged due to 1) cable' tray

. routing below the maximum expected flood level, and 2) cable tray routing from floor to floor. Generally, cable tray systems do not enter subcompartments which may have high j

. flood levels and are installed above calculated flood levels in other areas. Therefore, submergence of cable trays is not considered to be a problem.- These arguments are supported by Sargent & !. undy field confirmation of cable tray routing. A sample of more than seventy flood zones was examined by the field walkdown team, and observations substantiate the generalizations made above. in addition, a review of color-coded cable

~ ~

I8 0

routing drawings produced for Appendix R analysis supports these arguments for the auxiliary building.

The remaining concern is cable tray risers that pass through floors. The TVA floor opening I7'I9 design as indicated on TVA drawings includes embedded steel framing that extends four inches above the floor. Since all tray risers in the auxiliary and control buildings are in areas where calculated flood levels are less than four inches, submergence of cables in risers will not occur. No tray risers were identified in the ERCW pumping station or in the diesel-generator buildings. Therefore, cable tray risers passing through floors do not present a cable submergence concern.

Cables in Conduits TVA is currently assessing through field walkdown conduits that may become filled with water as a result of design hasis flooding. Conduits that have openings, fittings, etc., that are not watertight and are located below calculated flood levels may become filled. For the purposes of this study, Sargent & Lundy has assumed that required safe shutdown cables are either qualified for submergence or will be protected from submergence during tne time that they are required to operate.

In addition, Sargent & Lundy has assumed that conduit containing cables connected to safe shutdown power supplies and located in areas that may R

be affected by borated water flooding are qualified for submergence or are protected from submergence. As such, TVA must either implement physical measures (e.g., seal conduits) to

~ :

2G v 39 SARGENTD LUNDY 6-5 SL-4424 08-29-86 Rev.12-12-86 e_nsu.r.e;that r.equired cables do not become submerged or otherwise demonstrate that cable.

lR

~

submergence is acceptable. A method of establishing cable qualification for submergence has b. : :..

.. :3.m$arge.._..,.sn.nt & Lundy and transmitted to TVA under separate cover. g a.

.ac :2 3 u :~ : :. :' w-een developed by o

..j7..

. e.

7,,, 3. -

e x n u,...,3;..

at' 21.

ET'

~

w"' U

.s,

~

2.0: **;f! -

'.r t

' "a..:'.

4.,...

7.

.a.

.,p c-e..

' t "". e.;

. - ". t. '

u

".30l**

.. ;" ". 02.

~

  • ~

!.*. J.. t.

.v

?~^t.

?

s L?a -.'me.o...

._ L "O...

h..

O

  • 3.i' l'

4L.,. _ _

. '. I ~ ' C 3 ".

J.

.it'.

2 L. ~.. ShI k J.

Z.0 *

' c a U s a ' ' fa t*. '. 's.i...

w

  • i. ; T. as. *.

w i

,.w.

.L.

s. Tr~t*.

~

'U.

~ "'

j I

.....;' +

2 7 as-34' k

ty

  • ARGENT & LUNDY t ::. ' 1: n -

7-1

]

'S SL-4424 08-29-86 Rev.12-12-86 Rev. OM6-37 l

m.. :

...: 2. :. s;,w:.

.:. a e n a. g.ja..

,e 1

.: e re.::. a :n m..

- m :-

u.c.~;_.:._..,

i u..C.QNCLUSION5 ANDRECOMMENDATIONS w cer :r.w::t --

. The ability to achieve safe shutdown was demonstrated for postulated MELB flooding events provided the following recornmendations are implemented:

TVA Test Procedure SL-129, "ECCS Injection Pump Operability," should be revised to include the requirement for both Division A and Division B safety injection pump cubicle doors to be open during functional testing of either pump. This is only required during surveillance testing of the safety injecuon pumps and not during plant-wide SI signal tests. This requirement ensures that design basis MELB flood loads in these cubicles are less than the allowable live loads provided by TVA.

The auxiliary building / turbine building and control building / turbine building wall snould be flood protected to elevation 706 feet 0 inches.

HPFP lines in Zones 749.0-A6,749.0-A7, 749.0-A10, and 749.0-All should be shown to be equivalent to Seismic Category !(L) Pressure Boundary Retention. This may require sprinkler nead modifications.

Conduit containing cables required for MELB safe shutdown that are located below MELB flood levels should be sealed. Alternatively, the cables may be shown to be qualified for submergence.

Conduit containing cables connected to safe shutdown power supplies that are located below MELB flood levels in areas affected by borated water should be sealed. Alternatively, the cables may be shown to be qualified for submergence.

Revise the protective device settings for the following main circuit breakers i

in accordance with the recommendations centained in Sargent & Lundy Calculation No. SQN-EPS-001-1:

Board Byaker Location 480-V Shutdown Board 1 Al-A 480-V Shutdown 3 card 1 Al-A Cubicle IB 480-V Shutdown Board IBl-B 480-V Shutdown Board IB1-B Cubicle IB R

480-V Shutdown Board 2Al-A 480-V Shutdown Board 2Al-A Cubicle IB 480-V Shutdown Board 2Bl-B 480-V Shutdown Board 2B1-3 Cubicle IB

zr e 34 SARGENT & LUNDy 7-2 SL-4424 08-29-86 Rev.12-12-86 Rev. 03-06-87 Board Breaker Lockation C&A Building Vent Board 1 Al-A 480-V Shutdown Board 1 A1-A C&A Building Vent Board IB1-B 480-V Shutdown Board IBI-B C&A Building Vent Board 2Al-A 480-V Shutdown Board 2Al-A Verify the structural adequacy of walls and floors in Zones 669.0-A15,669.0-A16, 714.0-A7, and 714.0-A8 for the flood levels provided in NSLD Calculation 3C37-0686-001, Revision 3.II Flooding in the reactor building annulus must be limited to 2 inches'by providing free flow in the drain system or modification to the detection and isolation system.

The test return header to the refueling water storage tank and certain component cooling system piping in Zones 714.0-A7 and 714.0-Ab are assumed to meet the crack exclusion criteria.

Spurious operation of associated equipment that might prevent safe shutdown was not evaluated in this repcrt.

The effect of degraded bus voltage due to MELB flooding was not evaluated in this report. Sargent & Lundy recommends that TVA consider resetting the g

auxiliary building supply fan breaker to reduce the degraded voltage duration.

PROGRAM FOLLOWUP Sargent & Lundy recommends that TVA summarize implementation of the above recommen-dations through issuance of a TVA calculation "MELB Flooding-Summary of Corrective Actions."7 This calculation will document corrective actions taken by TVA to ensure that the intent of the Sargent & Lundy recornmendations is met.

u _

27 er 24

^

w SARGENTS LUNDY 7-3 SL-4424 08-29-86 R<:v. (2-12-86 Rev. 03-06-87 i

SARGENT & LUNDY Prepared by:

MY

'03-06-87 R..%. Fiela' Senior Safeguards Engineer Nuclear Safeguards & Licensing Division

....- eu.::r

+-. :s 7'

03-06 47 y

M. P/ Mur$y)

'/

.s Electrical Project Engineer..

,~

Electrical Project Engineering 'Didsion ~

/w 03-06 _

~ Rpiarsnalia '

~

Supervising Design Engineer Structural Engineering Division Reviewed bhi.

~

m 03-06-87

~~

'w. R. Peeoles V'

Supervisor

-'~,. ~ Nuclear Safegundsli Licensing Division

[

.d 03-06-87 R. M. Scniavont

' Senior Electrical Project Engineer Electrical Project Engineering Division

/ _,

03-06-87 A. T. Gojer Structural Project Engireer Structural Project Engirieering Division

,..4

)f, 03-06-87 I

Approvec by:

x 3C J. 5pstick Project Manager Froject Management & Engineering Division D,,,*,

a y;s.y a & AGgjggy.-.gre s.

ap" e

c# $5 4..

0F TO '..

/

n u..

l

Os o.= 34 S. AR.G.E.NT 8 LUNDY 8-1 n s.

Sg_4gyg 08-29-86 Rev.12-12-86 3 --

...... Section 8

~'

... e.2.. e -

REFERENCES ce ::: n,c r ;. ;

. a L.e...

)

TVA DOCUMENTS 1.

" Evaluation gf. th,e Effec,ts of Postulated Pipe Failures Outside Containment," TVA Report CEB'72-22, Revision 3, MEDS CEB 821007 001.

1 2.

" Report ortEtatection.Against.. Dynamic Effects of Pipe Failure Inside Containment,"

TVA Report CEB 76-03, Revision 0, MEDS CEB 801105 008.

f 3.

K. W. Schram, " Flooding in Auxiliary Building due to Postulated Pipe Breaks," TVA meviewCalculation,3ranctLIdentifier_S.QN DSG7-007, Revision 2, RIMS B45 860131219.

4.

C. P. Baxter, " Piping Critical Crack Exclusion Evaluation for SQN Flooding Study -

.SCR SQN NEB 8520," TVA Calculation, Revision 0, August 15.1986, RIMS B41860S15 001.

5.

" Equipment Required for Safe Shutdown for 10 CFR 50 Appendix R," TVA Calculation, Revision 5, MEDS B45 850514 218.

~

6.

" Analysis of Class IE I&C Power Systems for Post LOCA Submergence of Electrical Equipment," TVA Calcul& tion, Branch Identifier SQN-SMBG-1, Revision I, RIMS B43

~

860815 910.

l movm e:

7.

"MELB Flooding - Summary of Corrective Actions," TVA Calculat-lon, Sranch Identifier SQNESQ5%39; fpreliminsry).'

j 7a.

" Water Depth and Spray on Equipment Necessary for Safe Shutdown," TVA QlR-SQN-EEB-85003, June 29,1985.

R l

' 3/ er rs

-4 SARGENTE LUNDY 8-2 SL-4424 08-29-86 Rev.12-12-86 SARGENT & LUNDY DOCUMENTS 8.

" Work Flow for MELB Flooding Study," Sargent & Lundy Project instruction PI-SQ-04, Revision 0, June 3,1986.

9.

" Evaluation of the Effects of MELB Flooding Inside. and Outside Containment,"

Sargent & Lundy Project Instruction PI-SQ-05, Revision 3, December 3,1986.

R 10.

"Walkdown Procedures," Sargent & Lundy Project Instruction PI-SQ-06, Revision 2, August 28,1986.

I 11.

R. M. Field, et al., "MELB Flood Level Calculations," NSLD Calc. No. 3C37-0686-001, Revision 3, December 9,1986.

R l

12.

3. 3. Gustin, et al., " Structural Flood Load Assessment," SED Calc. Book No. SF-OP-g 01, Revision 3, TVA Branch V ntifier SCG-IS69.

i 13.

L. A. Langenberg, et al., "MELB Safe Shutdown Analysis," NSLD Calc. No. 3C37-0786-R 001, Revision 1, December 15,1986.

14.

Sargent & Lundy Design Information Transmittals DIT-SQ-MDD-001, 06/19/86 j

DIT-SQ-MDD-001-01, 06/26/86 DIT-SQ-MDD-002, 06/23/86 D!T-SQ-MDD-003, 06/25/86 DIT-SQ-MDD-004, 06/27/86 DIT-SQ-MDD-005, 06/28/86

32 g 34 4

SARGENT 5 LUNDY 8-3 SL-4424 08-29-86 Rev.12-12-86 5AF 26tf-SQ-MDO-006,T~

06/30/86 D!I-SQ-MD.D-007,g3 _06/30/86 3, DIT-SQ-MDD-008, 07/01/86 DIT-SQ-MDD-009, 07/02/86

'..o...

.m_

The.above D,ITs. transmit the "Confirmat.ory.Walkdown Data Sheets" and " Submergence Cata Sheets" from J. M. Luna (MDDD) to R. M. Field (NSLD).

.. e...

- '. a ;..

DIT-SQ-MDD-010, 07/22/86 The above DIT transmits supplemental " Confirmatory Walkdown Data Sheets" from J..J. Gustin (SED) to R. M. Field (NSLD).

DIT-SQ-MDD-011, 07/22/86

)

The above DIT transmits " Submergence Data Sheets"(which supercede previous sheets for certain zones) from J. J. Gustin (SED) to R. M. Field (NSLD).

i DIT-SQ-MDD-012, 11/03/86 The above DIT transmits " Submergence Data Sheets"(which supercede previous sheets for certain zones) from R. M. Field (NSLD) to M. A. Navarao (NSLD).

DIT-SQ-MDD-013, 11/26/86

]

The above DIT transmits " Submergence Data Sheets" from J. P. Kish (EPED) to R. M. Field (NSLD).

4

~

i i

.:rs or 34 SARGENT & LUNDY '

84 SL-4424 03-29-86 Rev.12-i 2-86 Rev. 03-06-87 DIT-SQ-MDD-013-1, 12/03/86 Tne above DIT transmits " Submergence Data Sheets" (which upgrade previously transmitted sheets for certain zenes) from J. P. Kish (EPED) to R. M. Field (NSLD).

DIT-SQ-MDD-013-2, 12/06/86 The above DIT upgrades three " Submergence Data Sheets" (which were previously transmitted). This DIT is from J. P. Kish (EPED) to R. M. Field (NSLD).

15.

" Safe Shutdown Power Supply Analysis," Sargent & Lundy Calculation, TVA Branch Identifier SQN-EPS-001, Revision 2, Caruary 27,1987.

R 16.

" Project Instruction for Use and Control of TVA Drawings -and Documents for Sequoyah Flooding Study," Sargent & Lundy Project Instruction PI-SQ-17, Revision 1, August 20,1986.

17.-

R. M. Schiavoni (EPED), to R. J. Suslick (PMED), " Electrical Department Document Control Log," Sargent & Lundy Interoffice Memorandum, February 24,1987.

R 18.

R. M. Field (NSLD), to R. J. Suslick (PMED), " Document Control Log - Revision 5,"

Sargent & Lundy Interoffice Memorandum, November 20,1986.

19.

A. T. Goier (SPED), to R. J. Suslick (PMED), " Structural Department Document Control Log," Sargent & Lundy Interoffice Memorandum, November 6,1986.

20.

W. R. Peebles, " System isolation for MELB Flooding," NSLD Calc. No. 3C37-0686-002, Revision 2, December 9,1986.

)

i i

av o,c J4 SARGENT S LUNDY E5 a. :s '.

SL-4424 08-29-86 Rev.12-12-86

. _.. -.,. ~...

21..

R. J. Suslick (S&L), to J. A. Raulston (TVA), " Evaluating the Performance of Insulation Co'mpounds Under Totally Submerged Conditions," Sargent & Lundy letter, August 23, 1986.

^

L' ; ~

' ; F. t " *. : - ' - _

~~-

OTHER DdCUMENT5"

" ~' ~ ' '

~

22.

" Determination of Break Locations and Dynamic Effects Associated with the Postulated Rupture of Piping," U.S. Nuclear Regulatory Commission Standard Review Plan.Section 3.6.2, Revision 1, July 1981.

ap 9

d-

. ;?*~. :..

4-t..5m

.e up.e 4

W e

4 4

r '.

., O  ;. "

~ *

- - g,,

w l'

a

9

,e s

t i

Appendix A l

Sargent & Lundy P~oject Instruction Pl-SO-05, I

Evaluation of the Effects of j

MELB Flooding Inside and Outside Containment"

=

8 b-401 J

e l

PROJECT SARGENT&LUNDY zusTRUCrzcu PI So-Os INSTRUCTION 2N8*****-

c-caoo REV. 2 Client TENNESSEE VALLEY AUTHORITY l

Project SEQUOYAU NUCLEAR PLANT Project No.

7659-00 i

i l

I

Title:

Evaluation of the Effects of MELB Flooding f

Inside and Outcide Containment l

1 I

O Safety-Related O non-Safety-Related Reviewed by:

Approved by:

Rev.

Date Sr. Elect.

Sr. Struct.

QA Project Project Engr.

Project Engr.

Coordinator Kanager,

,1 0

OGl03/86 f/ lb1

\\ )ffh(% QlM W W)S0 h/bY 1

08/28/86 f.[f Vk/% '. 0,._[hh(,4,4W ME dM[__b[

  • &. ~~,g., )f, m/J-& R,&}lf 2

12/03/86

,(A,0 l [

.( A ( J 1 i g i a l m 1 S e b i i 1 of 17 Page

l INSTRUCTION Pl. 50-05 l PROJECT SARGENT* LUNDY 1 INSTRUCTION ____ sue wo mme - REV. 2 TABLE OF CONTENTS PAGE 1.0 I nt roduc ti o n a nd Sco pe................................ 3 ) i 2.0 References............................................ 3 1 3.0 D e f i n i t i o n,s........................................... 4 I 4.0 Pi pe Fa i l u re C r i te r i a................................. 9 5.0 Assumptions........................................... 11 6.0 Fl o od i n g I nt e rac ti on.................................. 16 7.0 Ac ce pta bil i ty C ri t e ri a................................ 16 8.0 Requi rements for Summary o f Anal ysi s.................. 17 9.0 Exce pti ons to Accepta bil i ty Cri teri a.................. 18 i ~ ta n 5 eoo E 5 na. Page 2 of 17

__I,

-l iNsmcTioN m; SO,05 PAOJECT SARGENT 9 LUNDY . INSTRUCTION { _ _ spp,,'** * *

  • R 2

_.-. _ _ -- s -

1.0 INTRODUCTION

AND SCOPE i This Project Instruction delineates the criteria to be followed in evaluating the effects of flooding on safe snutdown capability following l postulated moderate energy fluid system line breaks (MELB) inside and l' outside containment. Evaluations of tne effects of high energy line -breaks.are beyond the scope of this Project Inst ruction. Many of' the criteria in SQN-0C-V1.1.11 " Evaluating the Effcets of 'a Pipo Failure.0utside Containment" and in SQN-DC-V-2.13 " Evaluating the Effects of a Pipe Failure Inside Containment; and in SQN-DC-V-2,13, " Evaluating the Effects of a Pipe Failure Inside Containment", (which apply to evaluations of pipe whip, jet impingement) are repeated in this document for use in' evaluating the effects of flooding. It is intended, throuah these criteria and supplemental detailed criteria, that the same pipe breaks are postulated and acceptance criteria are met (as - applicaole) for ev61uations of flooding as for evaluations of other moderate energy pipe break ef fects (see references 2.2 and 2.3). Other breaks are to be evaluated as necessary to assure that the' effects of flooding are conservatively bounded.

2. 0

' REFERENCES 2.1 NRC Regulatory Guide 1.29, " Seismic Design Classification." 2.2 " Evaluation of. the Effects of Postulated Pipe Failures Outside of Containment for Sequoyah Nuclear Plant, Units 1 and 2," Revision 3. CEB-72-2%, TVA Document MEDS Accessinn Number CEB 821007 001. 2.3 " Protection Against Dynamic Effects of Pipe Failure Inside Containment and the Main Steam Valve Rooms," Sequoyan Nuclear Plant, Revision 0, CEB-76-03, TVA Document MEDS Accession Number CEB 801105 008. ( -2.4 Shames, I.H., Mechanic of Fluig, Eq. (15-60), pg. 301, McGraw-Hill, 1962. l 2.5 Brater, E.F., and H. W. King, Handbook of Hydraulics, Eq. 4-l'0, p.4-3, ) McGraw-Hill, 1976. f 2.6 Crocker, S. and King, R. C., Pioing Handbook, pp. 3-26, McGraw. Hill' 1967. R e 8 .2. 7 "Sequoyah Nuclear Plant General Design Criteria for Evaluating the -[ Effects of a Pipe Failure Outside Containment," SQN-DC-V1.1.11, Revision 4, 9/12/84 Page 3 of 17 i s )

SO~0U ~ l SARGENT LUNDY msmuCTION N AROJECT INSTRUCTION _,awanseman-REV 2 ~ i 2.8 "Sequoyah Nuclear Plant General Design Criteria for Evaluating the Effects of a Pipe Failure Inside Containment," SQN-DC-V-2.13, Revision 4, Septemoer 4, 1984 2.9 Memorandum from John A. Raulston to R. A. Sesscms dated November 5, 1985 " Criteria Used by NEB in Determining Environmental Conditions for Electrical Equipment Qualification, "TVA Document - RIMS Accession Numoer B4685110S253. 2.10 OE Calculations " Flooding in Auxiliary Building due to Postulated Pipe Breaks," Revision 2, dated 1/31/86. TVA Document RIMS Accession Number B45851031219. 2.11 OE Calculations " Evaluation of Reactor Cavity Flooding due to Pipe Break j in an Open System," Revision 0, dated 1/7/80. TVA Document - MEDS i Accession Number NEB 810107 271. 2.12 OE Calculations " Flooding Levels in the East and West Valve Vaults - SQN Units 1 and 2," TVA Document RIMS Accession Humber B45 860225 235. ) 2.13 OB Calculations "Maximun Containment Water Level," TVA Document - MEDS Accession Number NEB 811005 262. 2.14 TVA Letter, f rom R. C. Wei r (TVA), to R. J. Suslick (S&L) entitled, "Sequoyah Nuclear Plant - Units 1 and 2, Flooding Evaluation - Comments R on Report and Supporting Calculation," dated. 0ctober 17, 1986. 3.0 DEFINITIONS 3.1 Acceptable Interaction An interaction for which, from a systems' standpoint, the net required I,afety functions of systems, structures, and components are not impaired following a postulated failure and a postulated single active failure. 3.2 Active Component Any component which must perform a mechanical mot' ion or change of state during the courne of accomplishing a safety function. 3.3 Circumferential Ruoture 8 A postulated piping failure where the break area shall be equal to the ef fective pipe cross-sectional area at the break location. i'he plane of 2 the break shall be normal to the pipe flow axis. Flow may be out of each end of the broken pipe depending upon the reverse flow capability. Flow will be modeled assuming a lateral offset of one pipe diameter. Page 4 of 17

,1 INSTRUCTION Pt. @ 05 PROJECT SARGENT s LUNDY INSTRUCTION _,,,u ,ue,,," AEv 2 m 3.4 Essential Structures. Systems, aad Components Structures, systems, and components required to shutdown the reactor and mitigate the consequences of a postulated piping failure including systems and components required to detect and isolate postulated piping failures. Essential structures, systems, and components are all required by TVA to be Seismic Category I. 3.5-Flooding Effects The direct and consequent hazards created by a flooded or submerged condition. 3.6 High Eneroy Fluid Systems For the purposes of thit Project Instructw., fluid systems that, during normal plant conditions, are either in operation or maintained pressurized under conditions where the maximum operating temperature 0 exceeds 200 F. This criterion is more conservative than that applied in References 2.2, 2.3, and 2.7 but reflects the actual criterion applied in evaluating the effects of flood.ing due to high energy line breaks (see References 2,9, 2.10, 2.12, and 2.13 ). High energy lines are not within the scope of the MELS flooding study. 3.7 Inside Containment For the purpose of these criteria, inside containment is defined to include all pipe and fittings inside the containment vessel and in the annulus and main steam valve rooms. (The actual containment boundary, i for integrity evaluation purposes, is normally taken as the second isolation valve.) 3.8 Moderate Eneroy Fluid Systems Fluid systems that during normal plant conditions, are either in operation or maintained pressurized (above atmospheric pressure) unoer conditions where the maximum operating temperature is 200 F or less. 0 O NOTE: The terms moderate and low energy (used in earlier pipe break ej criteria) have the same definition. 5 3.9 Normal Plant Conditions 8 Plant operating conditions during reactor startup, refueling, testing, E 3 operation at power, hot standby, or reactor cooldown to cold shutdown condition. Page 5 of 17

x 4 .s INSTRUCDON Pl. 50-05 PROJEC7 SARGENT' LUNDY INSTRUCTION s REV. 2 3.10 Outsiffe Containment Outside containment includes all of those regions not included in the definition of "Inside Containment" (subsection 3.7). I 3.11 ' Primary Safety Function The passive or active function of a structure, system, or component which must remain functional to assure directly: (1) the integrity of the reactor coolant pressure boundary (RCPB), (2) the capability to shut down the reactor and maintain it in a safe shutdown condition, or l (3) the capability to prevent or mitigate the consequences of accidents which could result in potential offsite exposures in excess of the guideline exposure of Code of Federal Regulations 10 CFR 100. 3.12 Postulated Pioino Failures i Through-wall leakage cracks postulated according to the provisions of this Project Instruction. 3.13 _P,rotective Structures or Compartments Structural units provided to separate or enclose redundant trains of safety-related systems or enclose high and moderate energy lines. (These structures are required to be Seismic Category I by TVA). 3.14 Reactor Cooiant ' Pressure Boundary (RCPB) Those pressure containing components such as pressure vessels, piping, pumps, and valves, which are: a. Part of the reactor coolant system (RCS) or b. -Connected to the RCS, up to and including any of the following: 1. The outermost containment isolation valve in system piping which penetrates primary reactor containment, 7 2. The second of two valves normally closed during normal reactor E operation in system piping which does not penetrate primary { reactor containment, and 8 3. The RCS safety and relief valves. E 3 3.15 Sa f ety-Rela ted Those plant features which perform either a primary safety function or a secondary safety function. Page 6 of 17 o


~---

^

i PROJECT-SARGENT 6 LUNDY ~ INSTRUCTION PI-SQ-05 l 1NSTRUCTION _,sevemasmo REV. 2 3216 Secondary Safety Function I The function of a portion of a structure, system or component which must retain limited structural integrity because its. failure could jeopardize, to an unacceptable extent, the achievemer.t of a primary safety function'or because it forms interface between Seismic Category I and Seismic Category I (L) or nonseismic ' plant features. t 3.17. Seismic Catecory I' Those structures, systems, or. components which ' perform primary safety functions are. designated as Seismic Category I and are designed and constructed so as to assure achievement of their primary safety functions at all times including a concurrent safe shutdown earthquake (SSE). ( 3.18 Seismic Catecory I(L) Those structures, systems, or components which perform secondary safety functions are designi.ed by TVA ss Seismic Category I(L) (i.e., limited requirements) and are designed and constructed so as to assure achievement of their secondary safety functions at all times including a concurrent SSE. 3.19 Shutdown Locic Diaoram A logic diagram that establishes system requirements for reactor scram and shutdown to cold-conditions. 3.20 _S Stresses under the combination of loadings associated with the upset plant conditions includin of equations (9) and (10)g 1/2 SSE loadings, as calculated from the sum in subarticles NC-3600 or ND-3600 of the ASME Boiler and Pressure Vessel Code, Section III. 3.21 _S h, 7 Basic material allowable stress at maximum (hot) temperature from the E allowable stress table in Appendix I of the ASME Boiler and Precsure j Vessel Code, Section III. J'$ 3.22 SA E ~ ,2 Allowable stress range for expanrion stresses, as defined in subarticles NC-3500 or ND-3600 of the ASME Boiler and Pressure Vessel Code, Section III Pa ge 7 o f 17 a_ -_--__.__.__.________m__.

W***** INST 9UCTION Pl.. S0 -05 PAOJEC7 SARGENT s LUNDY INSTRUCTION -,wm 3.23 S n, - I! Primary-plus-secondary stress ".,ttensity range, as calculatec from i equation 10 in Subarticles NB-3600 of the ASME Soller end Pressure Vessel Code,- Section III, for upset plar,t conditions (including 1/2 SSE and normal plant conditions loading effects). 3.24 Sm_ Allowable design stress-intensity value, as defined in Subarticle NS-3500 of the ASME Boiler and Pressure Vessel Code, Section III. 3.25 Single Active Component Failegg A singie active Silure is the failure of an active component to complete its intended function upon demand. It is the Icss of function of a component of electrical, mechanical, or fluid cystems. The failure of an active component cf fluid systcai is considered to be the failure if a component to perfons its function as a result of' mechanical. Lydraulic,-pneuuatic, or electrical nialfenction, but not the loss of emponent structural integrity. The direct. conseouances of p single active failure are evaluated. (A single active failure is postulated to ~ accur simultaneously with the postulated pipe failure; passne failures are not pos'..alated). 3.25 Throuch-Well Leakage Crack Fluid flow from a through-wall leakage crack shall be based or, a circular opening with an area equal

  • .,n an equivalent rectangular opening of one-half tne pipe inside diameter in length and one-half the wall thicknese in width.

NOTE: The terms through-wall leakage crack and critical crack (used in earlier pipe break studies) have the same definition, 3.27 Zone of Influence The maximum ohysical range of the direct effects of flooding re:,ul'.ing from a pipe failurs. 3.28 Uoset Plant Conditions 8 Plant operating conditions during system transients that may occur with moderate frequency during plant service life and are anticipated E 3 operational occurrences. Page 8 of 17

SARGENTMUNDY WSWCDON Pb SM PROJECT WSTAUCTION ___.swowes enn g g i 4.0 PIPE NAILURE CRITERIA For the purpose of postulating. pipe failure locations, the plant shall be assumed to be in the mode of upset plant operation (including loadings of one-half safe shutdown earthquack (1/2 SSE) and normal plant condition loading effects) in which the piping under investigation experiences the maximum conditions of operating pressure and operating temperature. For systems in which the maximum conditions do not occur during the same plant operating condition, the condition with the 4 4 highest calculated volumetric. blowdown rate through a postulated through-wall leakage crack shall be used. The following criteria shall be used to define the various pipe failure i types, sizes, and orientation and to determine failure locations 'for moderate energy piping components (only one failure is postulated to occur at a time). 4 4.1 Seismic Category I and I(L) (Pressure Boundar,v Retention) Pioino A through-wall leakage crack will be postulated in any one moderate energy pipe which exceeds a nominal pipe size of 1-inch where the following rules apply. I Piping systems that are located in areas where the subsequent a. flooding from a postulated piping failure could adversely affect structures, systems, or components which perform a primary safety function provided such postulated failures produce more limiting flooding coaditions and effects than previously postulated high energy breaks in the same areas, and b. Where the maximum stress, S. as defined in Section 3.0 exceeds 1.2 n S, or S as defined in Section 3.0 exceeds 0.4 (S +3 )* m h A 'lhe cracks should be postulated to occur individually at locations that result in the maximum fluid flooding effects. It shal' be located at any position on the pipe circumference or along the surface of the pipe. i 4.2 Non-Seismic and Seismic C'ateoory I(L) (Non-Pressure Boundary Retention) P_i oi n g a na Tan ks =4 j A throuigh-wall leakage crack will be postulated in any one non-seismic or I(L) (non-pressure bouncary retention) moderate energy pipe or tank e 9 with a nominal pipe size which exceeds a 1-inch and which could also affect structures, systems, and components which perform a primary SSE. This crack should be Pstulated concurrent with the ) safety fur.ction. j j i Page 9 of 17 o

-c SARGENTNNDY lNsmemN Pb PRoascT INSTRUCTION

es.awa m me "

REV. 2 f i 'The pipe may.be assumed to lose its pressure boundary at any location 'along its entirellength such as to maximize the flooding of equipment. j The failure is not limited to inline fittings, valves, flanges, welds, welded attachments, etc'., but may also be taken irt runs or branches of straight' pipe. A rupture of any one non-seismic or seismic category _ I(L) tank shall be postulated per guidance provided in Section 5.7. Cracks or ruptures shall be postulated to occur individua*ily with SSE. 4.3 Failure Time Regardless of pipe failure type, the failure shall be assumed to open-to its defined: size in 1 ms. 4.4 Failure Consequences The consequences of any flooding that may develop following the above postulated piping failures will. be evaluated. 5.0 ASSUMPTIONS In analyzing the effects of postulated piping failures, the following assumptions shall be made. (It is intended through the.use of censerva tiv assumptions relative to plant, system, and component operation / response before, during, and af ter a moderate energy line break, and use of conservative margins when calculating flooding levels, that the effects of detailed or complex phenomenon _that have not been considered (such as edge. effects on flow or dynamic effects) will be bounded or lessened.) 5.1 Operating Mode All normal plant operating modes (see subsection 3.9) shall be considered when evaluating the effects of a postulated pipe failure. 5.2 Sinole Active Component Failure e 3 A single active failure is the failure of an active component to 3 complete its intended function upon demand. A single failure shall be assumed in systems used to mitigate consequences of the postulated e 8 piping failure and to shut down the reactors. The single active failure is assumed to occur in addition to and concurrent with the postulated 2 piping failure and any consequences of the piping failure. When the postulated piping failure is assumed to occur in one train or division of a dual purpose moderate energy system (that is a system which is required to operate during normal plant conditions and to shutdown the Page 10 of 17 w___

.g I I b. s PROJECT I_ S0-05 I WSTRUCTION W SARGDiT *. LUNDY INSTRUCTION I __,s,vowee m ms REV 2 i l 1 k reactor), the single active component failure shall not be assumed to occur in. the redundant train or division,. provided the system is designed.to seismic Category I standards, is. powered from.both offsite { and onsite3 sources, and is: constructed, operated, and inspected to i quality assurance, testing, and inservice inspection standards appropriate for nuclear safety systems. { p 5.3 Available Systems. l All available essential systems, including.those actuated by operator l I actions, may be employed to mitigate the consequences of a postulated piping failure. In judging the availability of essential systems, icc~iiant shall be taken of the postulated failure and its consequences ~ such as unit trip and loss of offsite power and of the assumed single active component failure and its consequences. The feasibility of _ carrying out operator actions shall be judged on the basis of ample time and adequate ac_ cess to equipment being available for the proposed actions. 5.4 Offsite hower-When it is conservative to do so, offsite power shall be assumed to be avaiTi6Te during a' portion of or throughout the sequence of events that follow a pipe; failure. This. loss-of-offsite power shall be assumed to occur concurrently with the he postulated pipe failure and the single active s failure ur:- m:.2 es: If.however..a detailed analysis can be provided to show that the loss of offsite. power:is not a direct consequence of the pipe failure, then a loss of offsite power need not be assumed. 5.5 Unintended Operation of Equioment l The ps~r"fo'rmance of an unintended active function by equipment not within the zone of influence of a pipe failure shall not be postulated. Unint; ended operation of equipment within the zone of influence of the pipe failure may occur if caused by the pipe failure, provided the i unintended operation is a credible postulation. Unintended operation I g wit 1 not lieT6Hsi~dbHFtollace equipment in any operating mode other than those: modes for which it is normally required to function. a ...g. 5.6 Operator Resoonse ) 8 t It shall be assumed that a proper sequence of events is initiated by the E 3 operator to bring the plant to a safe condition, with the capability of ) going to a cold shutdown if required. However, it shall be assumed that Page 11 of 17 i - - - - - - - A

INSTRUCTION Pl. 50-05 SARG54.4 UNDY (' PROJECT INSTRUCTION ,sevowwa s ses. REE 2 no opdrator action is initisted for at least 10 minutes after pipe f a ilure. Additional time will be allocated for actions outside the main control room. 5.7 Tan ks Seismic Category I tanks shall not be assumed to fail. The effects of flooding due to failure of non-seismic category I tanks due to a seismic event shall be evaluated assuming an amount of fluid released equivalent to the internal volume of the tank. The initial compartment flood level should be based on the instantaneous release of the tank contents. The effects of automatic make-up systems and attached piping systems shall be considered as appropriate in the determination of subsequent fluid flow rate and volume released. 5.8 Flow Pcth ~ Fluid may to transferred from one area to another within the plant through many p6thways. The following sections provide information concerning'the methodology to be used to calculate flow rates between areas / compartment flood levels. The purpose of these calculations is to evaluate the resultar,t compartment flood levels. 5.8.1 Floor Drains For purposes of calculating compartment flooding potential and rates, floor drains shall be assumed to be plugged. However, if design provisions, engineering evaluation, and appropriate periodic tests and inspections demonstrate that these floor drains would not plug, they shall be assumed open. If drain lines from one compartment cross to other compartments, the potential for flooding in other compartments due to backflow shall also be assessed. Drainage flow from compartment to compartment shall be determined using conservative values. for entrance and exit loss coefficients for the drain line, and elevation differences (head) between the flood level in the upper compartments and drain line located in the lower compartment. l 5.8.2 Stairwells and Floor Openinos Fluid. removal from compartments via stairwells and floor openings shall 0 be assessed. This outflow may be calculated using the following expression (for flow over a broad crested wier): 1 Q = bg /2(2/3 h)3/2 (reference 2.4) } where: 3 Q = fluid discharge rate (ft fgee) Page 12 of 17 L

i \\ i ins m e m N N so-os i PROJECT SARGENT 9 LUNDY INSTRUCTION _waNowmans. RW 2 ) i I ti = unobstructed perimeter of the opening (f t) g = 32.2.ft/sec2 h = flood hei:y;r upstream of the opening (f t) Caution: j s The equation is valid for unidirectional flow over a broad crested l weir. Where multidirectional flow ccverage on a floor opening, edge effects may reduce the effective perimeter (b) of the opening and shall be accounted for in calculating the fluid discharge rate (Q). The effects of flooding on lower elevations due to water flowing down the stairwells shall be determined. Consideration shall be given to stairwell architecture and conservative values applied for the amount of { water assumed to be retained on each elevation. 5.8.3 Floor Sleeves Flow through unsealed floor sleeves may be considered where the outflow is conservatively considered as: Q = CA (2gh) /2 (reference 2.5) where: 3 Q = outflow (f t /sec) A = flow area = (D0-Of)/4(ft) 2 C = coefficient of discharge (typically 0.6) h = flood height (ft) 2 g = 32.2 ft/sec D = inner diameter of sleeve (ft) 0 Dj = outer diameter of pipe in sleeve (ft) 5.8.4 Doors ,1 O C Where Closed doors exist between Compartments, flow under these doors E i shall be evaluated. Provided the area outside the door is configured to carry away the outflow from the compartment, flow under a door may be modeled as flow under a sluice gate given as: Page 13 of 17

s h SARGENT4,LUNDY INSTRUCTION Pl. 50-05 PAOJECT INSTRUCTION I asoweemme.. g 9 0 (h-h )) 1/ (reference 2.6) 0= cb (2gh 0 where: 3 Q = outflow (ft /sec) c = coef ficient of discharge (typically 0.57) (reference 2.14) R ba door width (ft) 4 h = flood height (ft) h0 = height of gap under door (ft) 2 g = 32.2 ft/sec Outflow to other areas assuming the compartment doors are open shall also be evaluated ur,less it can be demonstrated that adequate administrative controls exist that would prevent these doors from being blocked open for more than 1 shift (8 hours). Credit may be taken for outflow through normally closed doors when it can be demonstrated that the flood level is sufficient to cause the door failure and door strength is conservatively calculated. 5.8.5 Dropout Panels No flow through dropout pariels shall be considered until the necessary flood height required to cause the panel to dropout is reached. At this time, flow through these openings shall be assessed in the same manner as outlined in 5.8.2. 5.8.6 Miscellaneous Penetrations Flow through otner unsealed penetrations shall be evaluated as applicable to each postulated pipe break. Examples of penetc.ations that j 1 may be significant are: cable tray penetrations, shield plug j penetrations, HVAC penetrations, grates, and louvers. 5.8.7 Accumulation j 1 Fluid released to a region will accumulate in that region as long as the f 8 release rate is grater than the discharge rate from the region. The E water height developed in each region shall be evaluated by comparing 2 the net inflow to the region with the net floor area of the region (i.e., the gross floor area minus blocked off regions such as pump foundations or flood walls). The water height shall be determined by calculating the net free volume of tne compartment in question. 4 Page 14 of 17 4 1

-. _ - ~ _ _ _ _ PAOJECT h .,(( INSTRUCTION Pl. 50-05 INSTRUCTION Conservati$eestimatesofthenetfreevolume'maybe.usedinlieuof actual values. 6.0 FLOODING INTERACTION An active component (electrical, mechanical, and instrumentation and control) shall be assumed incapable of performing its active function upon experiencing flooding effects exceeding its environmental ratings for submergence. However, credit for the component may be taken if sufficient time is a*vailable_ for accomplishing its function before environmental ratings are exceeded. Credit may also.be taken if the component's short-term (24 hours or less) environmental rating can be established and if it can be shown that the flooding effects resulting from the pipe failure can be limited to a corresponding short term. 7.0 ACCEPTABILITY CRITERIA ~ 7.1 General _.. The. capability to achieve a hot standby condition shall not be jeopardized even if the pipe failure is followed by a single active fai. lure. ; Failures in non-seismic or seismic category I(L) (non-oressure boundary :.retenti on ) p1 ping shall not damage either train of seismic category I systems..Tne system requirements and availaole reoundance snall be that snown on a shutdown logic diagram or a required equipment list for mitigating the effects of the postulated failure. i Although the design basis for acceptability is achievement of a hot standby condition, the capability to eventually achieve a cold shutdown condition, applying the same criteria, shall be evaluated and exceptions l documented. Long-term repair of sin *gle active failures may be con-sidered to assure achievement of the cold shutdown condition where such repairs can be shown to be practicable and timely, and provided the unit c7nTe~ held T5Tsafe state during the time required for the repair. The evaluation of such repair shall be considered on a case-by-case basis and the nuclear safety aspects associated with the repair shall be determined by the Neclear Safeguards and Licensing Division. 7 7.2 Civil G 7.2.1 frotFct We~ 5t ruct u res 3 The flooding effects of a postulated piping failure should not preclude 2 habitability of the control room or access to surrounding areas important to the safe control of reactor operations needed to cope with the consequences of the piping failure. Page 15 of 17

w 4 I INSTRUCTION Pl. 50-05 AR EN *.MDY PAOJECT-1NSTAUCTION amemmesses. 2 REV 7.3 Electrical System 7.3.1 Submergence of Multiple Electrical Components The integrity of required electrical safe shuten circuitry shall not be compromised by the submergence of multiple electrical components (including terminations and caoles) due to moderate energy line breaks. (Submergence of single components, i.e., single failures, are within the design bases for SQN and require no analysis.) For each j postulated.MELB, an operable electrical safe shutdown path shall be identified anu documented by appropriate shutdown logic diagrt.ms or equipment lists. Submergence of low and medium voltage auxiliary power components and terminations not required for safe shutdown but supplied from required sources shall be analyzed as follows: 1. For a given submergence zone, determine the component (s) submerged and the associated power source (s). If only single faults for each source result from the MELB, i.e., one submerged component per power source, no further analysis is required; single failures are within the he design basis of SQN. Document the submerged components and associated power sources to verify existence of single failure only. 2. Should multiple faults exist on a power source as a result of I i submergence, an analysis shall be performed to verify (a) the existence of a separate, fully operable safe shutdown path or (b) clearing of the power system faults by associated electrical protective devices without loss.or degradation of the power source. Document as applicable for the approach employed. 8.0 REQUIREMENTS FOR SUMARY OF ANALYSIS A final report will be prepared to document the flooding evaluation. Sufficient information shall be provided such that an independent review can be performed. The final report shall provide guidance on the use of supporting MELB flooding calculations, the conclusions drawn, and any g reconrnended corrective actions. e i 3 9.C TT.CEPTIONS TO ACCEPTABILITY CRITERIA l J .9.' Submergence of Multiple Control Voltage Level Electrical Comoonents E ) 2 Submergence of control voltage level electrical components (including terminations and cables) not required for safe shutdown requires no 1 detailed analysis: tne high resistivity of borated, demineralized, raw, and potable waters limits submergence related f ault currents to Page 16 of 17 o

,v - - _. _. =.- INSWCTION R. 50-OD' PROJECT SARGENT *, LUNDY INSTRUCTION g magnitudes..approximately equal to (for borated water) or much less than (all other water) normal circuit load current. Thus, given st'andard board loadino and di v_ef.3_i_ty2 'no p.owen.s.ource degradation occurs. This engineering evaluation shall be documented with the MELB analysis. ,pq Q~'yg* pae- ,;. g.. ,7 L ...~I ^'J*9' s., I ~ h; W. FOP..'.'

  • st O s "*

~ g e g o ' :.':. - - _... - -. '.. ; 7 e 'Oo E ~ B w Pape 17 of 17 .. - _ _ _. _ -. _ _. _ _ _}}