ML20217N864
| ML20217N864 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 03/27/1998 |
| From: | Kennedy M, Moody J, Oregan P ENTERGY OPERATIONS, INC. |
| To: | |
| Shared Package | |
| ML20217N838 | List: |
| References | |
| NSD-023, NSD-023-R00, NSD-23, NSD-23-R, NUDOCS 9804090232 | |
| Download: ML20217N864 (122) | |
Text
Arkansas Nuclear One - Unit 2 Pilot Plant Study Risk-Informed Inservice Inspection Eva:Luation for the Service Water System consisting of the following:
Calculation No. NSD-023: Consequence Evaluation ofANO-2 Service Water System Report No. SIR-98-011: Evaluation ofDamage Mechanismsfor the Service Water System at Arkansas Nuclear One - Unit 2 Report No. SIR-98-026: Service History and Susceptibility Review, Risk Evaluation andElement Selectionfor Arkansas Nuclear One - Unit 2 March 1998 l
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Page1 J;alculation No. NSD-023 ORIGINAL PAGE 1 of122 PAGES
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Rev.1: PAGE 1 of PAGES V
Rev. 2: PAGE 1 of PAGES Rev. 3: PAGE 1 of _ PAGES QA RECORD?
RECORD TYPE NO.
13.C16.053 X YES Safety Class /P.O. NO. (if applicable) N/A
__ NO YANKEE NUCLEAR SERVICES DIVISION CALCULATION / ANALYSIS POR TfrLE Conseauence Evaluation of ANO-2 Service Water System PLANT Arkansas Nuclear One - Unit 2 (ANO-2)
CYCLE N/A CALCULATIONNUMBER NSD-023 PREPARED BY REVIEWED BY APPROVED BY SUPERSEDES
/DATE
/DATE
/DATE CALC./REV. NO.
ORIGINAL J.H. Moody P.J. O'Regan M.F. Kennedy N/A (JHM Consulting)
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(DE&S)
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KEYWORDS: Inservice Inspection (ISit Frobabilistic Risk Assessment (PRA). Risk Based. Risk Informed. ASME Section XI. Conscouence Analysis. Piping COMPirfER CODES:
NfA EQUIP / RAG NOs.:
N/A SYSTEMS:
N/A RETERENCES:
See Calculation Pace 66 FORM WE-103-1 Revision 4 r
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1 Page 2 Calculation No. NSD-023 CALCULATION / ANALYSIS REVIEW CALCULATION NO.
NSD-023 REVISIONNO. 9 COMMENTS RESOLUTION i
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Identify method (s) of review:
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,X. Calculation / analysis resiew
_ Alternative calculational method
_ Qualificationtesting Resolution By:
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Commentf Cont' ued on Page:
/V1'f Concurrence with Resolution
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Reviewer /Date FORM WE-103-3 Revision 5 O
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Page 3 Calculation No. NSD-023 NED ANALYSIS PROCESS CHECKLIST Preparer Reviewer Name J. H. Moody Name P. J. O'Regan (please print)
(please print)
Organization J.,H. Moody Consulting, Inc.
Organization DE&S Signature h$M, -
Signature f[////f'//,., a S g,jgEff f k l ltf 8 '
Date Date
<f, Reautrement Preoarer Reviewer Ensure that the method described in the MOM, if applicable,
/[A A//4 and the base calculation, if one exists, has been followed
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If not, ensure lead engineer / manager is consulted and I
document variation in calculation b
$10 E Ensure that other applicable NED Procedures are implemented Ensure inputs / assumptions are obtained from appropriate fToW
[
sources Ensure any change to an input / assumption is consistent with 4A N /A-
/
operating practice at the plant Ensure that the safety analysis conforms to applicable LN d//4 requirements
'/
Ensure that intermediate results that would require a change to
//
h/A-plant operating practice are dispositioned and documented
/
Ensure, if reporting preliminary results, that the standard Al
///d memorandum clearly states the results are preliminary and
/
provides the status of the final analysis Ensure that issues found when performing an analysis are
//7 A/!N
/
dispositioned and documented Ensure a standard memorandum is written describing the 2
analysis performed and containing the following elements:
Any documents affected by the analysis are A//1 M/d updated
/
Recommend updates be incorporated in the A/M h
affected documents and include an action taken
/
feedback block DU ano_swl. doc 3/26/98
Page 4 Calculation No. NSD-023 NED ANALYSIS PROCESS CHECKLIST (continued)
Reautrement Preparer Reviewer N
A!/ 4-If the memorandum recommends updates to affected documents, copy the NED
/
Administrative Assistant
]
Provide a list of personnel for distribution at F W12.
l' YNSD and the sponsor A/!d N/h Notify project and sponsor licensing groups of any NRC reporting requirements
/
include a safety evaluation,if a plant operating Md
_,pk practice is affected
/
Ensure that this checklist has been filled out and is attached to D '/L both the memorandum, placed in department chronological
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files, and the calculation. [ NOTE: The checklist does not need to be attached to distributed copies of the memorandum.)
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rage 5 Calculation No. NSD-023 NED WE-103 REVIEW CHECKLIST
,,;vj Reviewer Compliance Reviewer Name P. J. O'Regan Name (please print)
(please print)
( IL qth h c h oy Organization DE&S Organization DE&S Signature
((
//'[ j Signature
[d/ [()
,h y
<y y
Date z.,7g y[
Date
'} l,)flq f Reauirement Reviewer Compliance Reviewer Ensure the title page is appropriately filled out.
RM'/L Correct number of pages.
QA Record filled out.
IMS number filled out. N/4 Th Rev '1 Fcon wE-/of -l T/?-
Record number filled out (13.C09.001 included if microfiche oc NhfB
+
hard copy of computer runs are attached to the calculation).
Descriptive title.
+
Plant, cycle number and calculation number included. "N/A" can be used for plant and cycle number.
Signatures and dates are included, and are in correct chronological order. Print the name and individuals' organization (if other than YAEC) below the signature. The title page reviewer g3 (v) and approver dates do not pre-date any date in the calculation except for changes containing that individual's initials and date.
All WE-108 computer codes and other keywords not in the title which can be used to retrieve the calculation are listed in the M/
keyword field.
Ensure the Form WE-103-2 is included and properly completed when a D /4 U/9 computer code is used.
Ensure Form WE-103-3 is included, and has signatures / dates from both Phn '/2-AM the preparer and the reviewer and that all comments have been addressed.
If no comments, use the following statement:
- Reviewed in accordance with WE-103 with no comments".
Ensure review of the calculation can be done without recourse to fMR N/A the originator.
Ensure computer codes are used in accordance with WE-103 N I4
/N Steps 4.1.4.1 through 4.1.4.6.
Ensure the calculation includes a title page, objective, method, inputs, 9_TD 't?
/4 7' assumptions, calculations, results, conclusions and references.
Ensure the inputs are referenced to formal documents, e.g., WE-103. The PD '/2 N/A reference can not be a YAEC report unless formal QA records are checked l
l and also referenced.
rN Ensure design input internal and extemal correspondence is prepared and 93D '/2 N/A l()
reviewed, and is, therefore, a QA record. If there is only one signature on the correspondence, verify that it is a QA record, ano_swl. doc 3/26/98
Page6 Calculation No. NSD-O':3 Reauirement Reviewer Compliance Reviewer
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Ensure that if design specifications wt te used as input to the calculation, At/4 N/A the performance characteristics are verified in writing by the provider of the component / product or by cognizant YAEC/ plant personnel.
Ensure that,nput and modeling uncertainties are explicitly addressed FTo'n N/A in the calculation.
Ensure that the applicable inpot considerations from WE-100, Table 1 P3D ' /2_
N/A have been incorporated and are explicitly addressed within the calculation.
Ensu e individuals responsible for each portion of the calculation are Allel Al/S identified when multiple preparers and/or reviewers are utilized. Page initiating is optional, even in the cases where initial boxes are provided on the pages.
Ensure each page has a page number and the calculation number and pee
/%-
revision number if applicable. Dates on each page are optional.
Ensure that every page of every attachment (or Appendix) contains its N lA*
Al/4 attachment (or Appendix) number.
Ensure a conclusion is stated in a supplemental Revision.
Ar/A
,t/ /4 Ensure corrections are addressed in one of the following approaches:
PJD '/L MC Retyped and identified by a vertical line with revision number, if applicable,in the right margin; OR Lined out, initialed and dated by preparer, OR
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Photocopy of original to eliminate any previous correction tape, whiteout, or erasures.
j Ensure enhancements and clouding are initialed and dated.
N /4 Md Confirm legibility meets WE-103, Attachment A. Specific pages can be f'3D GL M[
exempt if they are: (1) documents receivt.d from nother organization who is the original QA custodian, or (2) supplemental les included for information only. In these two cases, make su.-
,emo wasissued to RMS per WE-002 Section 3.4.3.
Review of 10CFR50.46 reporting requirements has been documented for A/ /4 N/A analyses which assess conformance with 10CFR50.46.
Ensure computer codes are validated for the computing environment.
_, /U /4 N/A Ensure script files are included in the calculation or referenced to another A//A N/A calculation. Also, ensure the preparer identifies how the code / script was run.
Ensure applicable outstanding Engineering Deficiency Reports (EDRs) have P38(t N/A been reviewed forinfluence on the calculation and note review in calculation.
Ensure relevant SER conditions / limitations have been reviewed for their 6J[A" effect on this calculation and the review is noted in the calculation.
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Page 7 Calculation No. NSD-023 Table of Contents O
1.0 OBJECTIVE AND SCOPE 8
2.0 METHOD OF SOLUTION 9
9 2.1 SununaryofEPRIMethodolog 2.2 Quar"*stive Basis 13 i
3.0 INPUTS AND ASSUMPTIONS 19 3.1 IPE Review 19 21 3.2 SafetyFunctions 22 j
3.3 Plantimel Assumptions l
4.0 ANALYSIS 31 4.1 Configurations &PipeRuns 31 36 4.2 Spatial ArrangementandWalkdown 43 4.3 InitiatingEvents 44 4.4 MitigatingCapability 4.5 Containment & Combinations 45 5.0 RESULTS 54
6.0 CONCLUSION
S & RECOMMENDATIONS 65 l
7.0 REFERENCES
66 l
APPENDIX A - CONSEQUENCE ANALYSIS RESULTS (SW SYSTEM) 71 ano_swl. doc 3/26/98
I Page 8 Calculation No. NSD-023 l(G^ 't 1.0 Objective and Scope l
This analysis documents th:: implementation of the Electric Power Research Institute (EPRI) risk-informed inservice inspection (RI-ISI) consequence evaluation at the Arkansas Nuclear One -
Unit 2 (ANO-2) nudear power plant. The objectives of the EPRI RI-ISI evaluation process are to l
identify risk signific.:nt piping, define the elements that are to be inspected within this risk l
significant piping, and identify appropriate inspection methods. As part of determining the risk significance of piping, the consequence evaluation focuses on the impact of a pipe failure. In the consequence evaluation, probab:listic safety assessment (PSA) techniques and insights are used to determine consequence categories as described in Reference 1.
The objective of the analysis presented here is to categorize the consequence (s) of pipe failures for the ANO-2 Service Water System (SW). The scope of piping covered by this analysis includes service water system piping greater than 1 inch nominal pipe diameter. The consequence analysis (Appendix A) documents the analysis of piping greater than 4 inch nominal pipe diam &r which includes the main supply and return headers, including the component cooling water (CCW) and fuel pool cooling (FPC) beat exchangers. This scope also inc.ludes the most important safety loads such as emergency diese'.sjacket cooling and ECCS cooling. Also, the containment coolers are included in this scope. The resub of this evaluation are used to draw conclusions about smaller pipir.g (equ:0 to and ! ass than 4 inch nominal diameter).
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Page 9 l
Calculation No. MSD-023 2.0 Method of Solution p
U The consequence evah'.ation is conducted assuming pipe failure (loss of pressure boundary integrity). A pipe failure can occur at almost any time either causing an initiating event or disabling the corresponding system or train during standby, periodic tc-ting, or a real accident demand. The same failure can also inipact the availability of other maigating systems. These consequence scenarios are analyzed per Reference 1.
2.1 Summary of EPRIMethodology As described in Section 3 of Reference 1, in the consequence evaluation, a pipe failure (loss of pressure boundary integrity) is analyzed with respect to impact en plant operation. Both direct and indirect impacts are corr,idered:
Direct - the failure results in a diversion of flow and a loss of the corresponding train / system i
or an initiating event. If flow divnsion or isolation of a pipe failure can cause loss of a train or system function, this is assumed to be the case. This is conservative because pipe failure is always assumed large enough to either disable the system or lead to isolation of a train or system.
d p
Indirect - the failure results in depletion of a tank and loss of system (s) supplied by the tank, (j
and/or spatially impacts other train / system (s) due to spray, flooding, etc. Since it takes time i
for flooding and draining impacts to occur, detection and isolation capabilities are an important consideration in assessing these impacts. The spatial location and impacts of propagation are assessed for each assumed pipe failure.
A consequence category is assigned based upon the above impacts including the isolability or failure to isolate the break, and the number of available mitigating (ur.affected backup) trains.
Four consequence categories are used: Hig' ) r!ium, Low, and None. The "High" category represents events with a significant impact un plant safety, while the " Low" category represents events with a minor impact on plant safety.
Consequences are ca'egorized in different importance categories based on the logic structure of the plant IPE. The logic structures specifically examined in this process are:
the event tree and system models the critical failure combinations, and e
the success paths e
l The critical failure combinations and the acceptable success paths are analyzed fcr each safety function in order to determine the level of plant protection and importance of different mitigating O
functions.
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Olculation No. NSD-023 The basic consequence rankmg philosophy, used in this analysis, can be summarized as:
"High" Rank: Pressure boundary failures resulting in events which are imponant contributors to the plant risk or pressure boundary failures which l
significantly degrade the plant's mitigating ability.
" Low" Rank: Pressure boundary failures resulting in anticipated operational events or pressure boundary failures which do not significantly impact the plant's mitigating ability.
" Medium" rank is included to accomm'>date failure events which do not obviously belong to the "High" or " Low" rank.
The analysis is conducted slightly differe it deperding on whether or not pipe failure causes an initiating event. The following provides examples to explain these differences and the general r ~thodology:
- l. Initiating Event - A pipe failure causes a LOCA without failing any other system or train.
This is a direct impact and for this example there are no indirect impacts. When the pipe failure causes an initiating event, Table 2-1 or Table 2-3 is used to determine the consequence category. Since the described event causes an initiating event with no impacts on mitigating trains, Table 2-1 applies. A medium LOCA (M)in Table 2-1 leads to a "High" consequer.e.
- 2. No Initiating Event - The pipe failure does not cause an initiating event. In this case, Table O
2-2 is used to determine the consequence category. The total impact is assumed to include the V
train containing the pipe failure and a spatial impact on two cther systems due to draining the tank and flooding. Further it is assumed that there are two unaffected backup trains available for mitigating the event, unavailability of the system containing the pipe failure requires a plant shutdown within 1 day (short AOT in Table 2-2), and the system is required to mitigate design basis category IV accidents in Table 2-2. With 2 unaffected backup trains, the consequence category is " Low" in Table 2-2.
- 3. Combination Event - The pipe failure causes both an initiating event and impacts mitigative systems, therefore, Table 2-3 applies. It is assumed there are three unaffected backup ti. ins available to mitigate the event. Based on Table 2-3 the consequence category is " Low" unless the consequence category for the initiating event in Table 2-1 is higher. Ifit is further assumed the initiating event is a medium LOCA, then using Table 2-1, the final consequence category becomes "High."
The above provides an example of how the importance of pipe failure is analyzed. In example 1, tlie initiating event is consi iated and using the results of the IPE, a consequence category is determined. In example 2, nJtigating system impacts are assessed and, based on the number of mitigative trains available and the likelihood of system demand during an applicable exposure time, a consequence category is determined. For example 3, the combination impacts are considered and, again, mitigative capabilities are determined and tre initiating event impact are determined using the results of the IPE.
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Caletttion No. NSD-023 The above examples and their reference te Tables 2-1,2, and 3 determined pipe failure (V) importance relative to core damage. Pip s failure must also be asseseed fbr impacts on centainment performance and their potential for unisolated LOCAs outside :ontainment. T61es 2-2 and 2-3 are also used to extend the analysis to assess containment peribrmance. The scope of svetems in this analysis does not include piping connected to the reactor coolant pressure boundary with respect to potential LOCAs outside containment. However, Table 2-4 is included for completeness to show how such piping would be intependently analyzed.
The following provides additional explanations of the methodology and the tables used in the analysis and discussed above.
Table 2-1: This table has been revised from Reference I to be ANO-2 specific, based on conditional core damage probability for each initiating event type. This table provides the minimum consequence category when pipe failure causes one of the plant specific initiating events. If additional impacts occur to mitigating systems due to the pipe failure, Table 2-3 must also be used. Table 2-1 also includes potential LOCAs in the containment for piping beyond the first reactor coolant isolation valve (See Table 2-4 for potential LOCAs outside containment).
Table 2-2: This table is used when pipe failure does not cause an initiating event, but affects plant mitigating functions;it has also been revised from Reference I to be ANO-2 specific. Assigning consequence categories when the mitigating ability of the plant is affected depends on the following attributes:
O)
- 1. Frequency of pipe challenge, which determines how often the mitigating function of the
(
system / train is called upon. This corresponds to the frequency of plant initiating events (i.e.,
not pipe failure frequency) that require the system / train operation.
- 2. Number of unaffected backup systems / trains, which determines how many unaffected systems or trains are available to perform the same mitigating function. The availability of multiple trains makes the effect of the loss of systems / trains less significant. Mitigative systems should be evaluated for each plant safety function (e g., reactivity control, RCS inventory, decay heat removal). When considering the consequences, given an isolation failure, the number ef trains must also include isolation.
- 3. Exposure time determines the downtime for the failed systems / trains, or the time the systems / trains would be unavailable before the plant is required to be shutdown, or the time required to repair the break. In this analysis, it is always assumed that the time to repair is greater than the allowed outage time (AOT). Exposure time is a function of the test interval, the detection time, and AOT. AOTs are plant-specific and, usually, short for important safety components. The key attributes in detennining the exposure time are the system states when the pipe failure is expected to occur (standby, test, or real demand), and time required for break detection (means available to detect the diversion of flow).
Four different exposure times are considered:
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Page 12 l
Calculation No. NSD-023 "All Year," which applies to standby systems and parts of systems where the run of piping f,]
is not " tested" or is not exposed to the loading condition ofinterest during a year.
l(
,V "Between Tests" applies to standby systems,.dich are regularly tested (monthly or quarterly). It is assumed that for those systems the actual exposure time is equal to the test interval (1 to 3 months), because, if a degraded condition is present, it will be discovered during the test.
"Long AOT" exposure time applies to operating or standby systems where pipe failure will be detected within a short time after the occurrence, and the plant will shutdown if the i
failure is not recovered (i.e., repaired) during the AOT. The exposure time is, therefore, equal to the AOT plus detection time. A "long AOT" exposure time is I week.
"Shoit AOT" exposure time applies to the same systems as the "Long AOT," the exposure time is less than or equal to 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
Table 2-2 also incorporates guidance for assessing containment performance. If there is a containment barrier available, the consequence category determined in the table for core damage is retain:d. If there is no barrier or failure of the only available barrier is used in determining the consequence category for core damage, some margin in the consequence category must be present to retain the consequence determined for core damage. If there is no margin, the consequence category is increased as shown in the table.
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Table 2-3: This table is used when the impact of pipe failure results in both an initiating event, as well as other direct impacts, and/or indirect impacts, such as loss of mitigative system (s). It is used in combination with Table 2-1 in that the higher consequence category is always selected.
The number of unaffected backup systems / trains available to perform the mitigating functions is determined. The availability of multiple backup trains could make the effect of the loss of systems / trains less significant. Systems should be evaluated for each plant safety function (e.g.,
reactivity control, RCS inventory, decay heat removal). When considering the consequences, given an isolation failure, the number of backup trains must also include isolation.
Table 2-3 also incorporates guidance for assessing containment performance. If there is a containment barrier available, the consequence category determined in the table for core damage is retained. If there is no barrier or failure of the only available barrier is used in determining the consequence category for core damage, some margin in the consequence category must be present to retain the consequence determined for core damage. If there is no margin, the consequence category is increased as shown in the table.
Figure 2-1 further summarizes the methodology and spplication of the tables described above.
1 The figure shows the affects of successful and unsuccessful isolation of a pipe failure. When evaluating the impacts ofisolation failure, this failure etn be equivalent to an available train depending on detection, time available, and physical cap ability (i.e., MOV or trip pump). In the example shown, the reliability ofisolation is assumed to be worth "I train." If pipe failure causes Il an initiating event (IE), only this portion of Figure 2-1 is utilized. Given an initiating event, and an l
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Page 13 Calculation No. NSD-023 assumed exposure time of"All Year," the accident demand case is enveloping. If no initiating O
event is caused by the pipe failure, the " accident demand" configuration is analyzed when applicaole, because it envelopes the exposure time for the " normal" and " testing" configurations.
Table 2-4: All piping connected to the reactor coolant pressure boundary and beyond the first isolation valve are evaluatM as potential unisolated LOCAs outside containment using this table.
Piping inside the containment and between the first reactor coolant pressure boundary isolation valve and the containment wall is evaluated in Table 2-1 as a potential / isolable LOCA.
l 2.2 Quantitative Basis The ANO-2 IPE, supplemented with design basis information, is used to define the quantitative basis for applying the EPRI procedure to the consequence evaluation at ANO-2. Figure 3-1 summarizes ANO-2 success criteria for different safety functions.
The following values for conditional core damage probability (CCDP) assuming a pipe failure are utilized by the EPRI methodology to assign consequence categories:
Low CCDP s IE-6 Medium lE-6 < CCDP s IE-4 High CCDP > 1E-4 O
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Page 14 Calculation No. NSD-023
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Table 2-1 Consequence Category Assignment for ANO-2 Pipe Failures Resulting in Initiating Events
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initiating Event IEF CDF CCDP Consequence (2)
T1 - Turbine trip 7.6E-01 2.3E-06 3.0E-06 low-medium T2 - Loss of PCS 2.5E-01 9.0E-07 3.6E-06 medium-low T3 - LOSP 5.8E-02 1.7E-06 2.9E-05 medium i4 - Excessive FW 9.4E-C4 1.9E-09 2.0E-06 low-medium T5 - Stram/ Feed break 1.lE-03 1.lE-09 1.0E-06 medium (3)
T6 Ector Trip 2.0E+00 6.0E-06 3.0E-06 low-medium T7 - Loss of SW 5.5E-03 2.1E-06 3.8E-04 high T8 - Loss of SW P4A 7.4E-02 2.lE-07 2.8E-06 medium-low T9 - Loss of SW P4B 7.4E-02 2.0E-07 2.7E-06 medium-low T10 - Loss of DC D01 3.9E-04 9.8E-06 2.5E-02 high Til - Loss of DC D02 3.9E-04 _1.lE-06 2.8E-03 high T12 - Loss of AC A3 3.9E-04 3.2E-06 8.2E-03 high T13 - Loss of AC A4 3.9E-04 5.8E-08 1.5E-04 high-medium T14 - Loss of AC B5 1.0E-03 1.9E-07 1.9E-04 high-medium T15 - Loss of AC B6 1.0E-03 1.2E-07 1.2E 04 high-medium S - Small LOCA 5.0E-03 1.7E-06 3.4E 04 high-medium M - Medium LOCA 1.0E-03 1.7E-06 1.7E-03 high fx A - Large LOCA 1.0E-04 1.4E-06 1.4E-02 high C.J R-SGTR 9.8E-03 9.5E-08 9.7E-06 medium Potential / Isolable LOCA (1)
(1)
(1) low-medium ISLOCA (1)
(1)
(1) high 3
l (1) Piping connected to reactor coolant pressure boundary is not included in the analysis scope; included for completeness. Consequence depends on isolation failure likelihood and other conditions. Also, see Table 2-4.
(2) When CCDP is close to a lower consequence, a range is shown. The first consequence shown in the range is assumed in the analysis. In the case of transients (T1, T4, and T6), a low consequence is assumed in the analysis. The IPE is judged to be conservative (e.g., additional credit for AFW and human actions) relative to other initiators (e.g., note T5 CCDP is lower) and the CCDP value is close to the IE-6 threshold. Other initiators that are marg:nal could be evaluated further with the IPE to determine whether a more realistic CCDP is possible.
(3) Steam & Feedwater breaks although marginally low are considered a severe plant challenge (e.g., high energy lines) and assumed to be medium consequence.
Initiating event frequency (IEF) is from IPE Table 3.3-6 (page 3.3-23) and core damage frequency (CDF) is from IPE Table 3.5.4-7A (page 3.5-59).
The above events can be assigned to design basis categories as in Reference 1 (Table 3.2) by considering the IPE initiating event frequency (IEF) in the above table.
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Page 15 Calculation No. NSD-023 Table 2-2 Guidelines for Assigning Consequence Categories to Pipe Failures Resulting in Loss of 49 System (s)ffrain(s) Without an Initiating Event V
Affected Systems Number of Unaffected Backup Trains Frequency of Exposure Time Challenge to Challecge 0
0.5 1.0 1.5 2.0 2.5 3.0 2 3.5
'W Allyear L
Anticipated Between tests (13 month)
(DB Cat II)
Long AOT(1 week) l Shc.rt AOT(s 3 day) iWi L
L Allyear
- g y b
Infrequent Between tests (1-3 month)
(DB Cat III)
Long AOT(1 week) k Short AOT(s 3 days) i, Allyear f
Unexpected Beturen tests (1-3 month)
(DB Cat IV)
Long AOT(1 week) f ff Shon AOT(s 3 days)
High Consequence Category H
e Medium Consequence Category M e Low Consequence Category L
=
Containment Performance - If there is no containment barrier and the consequence category is de ined by a diago al shaded box, the consequence category is increased.
- Low becomes Medium O
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Page 16 Calculation No. NSD-023 Table 2-3 Guidelines for Assigning Consequence Categories to Combinations of Consequence Impacts (Initiating Event and Mitigating Train (s)/ System (s) Impact) l Combination ofInitiating Event &
Consequence Category l
Mitigating Ability Affects Less than 2 unaffected backup trains available for mitigation lM: ldtMEDl55d
?;$8Y At least 2, but less than 3 unaffected backup trains k IE 2h available for mitigation hdefQifhigli&R6 g
LOW At least 3 unaffected backup trains available for (or IE category from Table 2-1, mitigation ifhigher)
No mitigating ability affected IE category from Table 2-1 Note: Mitigating systems always correspond to the analyzed initiating event.
Containment Performance -If there is no containment barrier and a minimum number of unaffected backup trains, the consequence category is increased as follows:
2 unaffected backup trains and no containment barrier: " Medium" becomes "High." If the number of unaffected trains is between 2 and 3, " Medium" is retained.
3 unaffected backup trains and no containment barrier: " Low" becomes " Medium." If the number of unaffected trains is greater than 3, " Low" is retained.
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Page 17 Calculation No. NSD-023 Table 2-4 Guidelines for Assigning Consequence Categories to Pipe Failures Resulting in Increased Potential for an Unisolated LOCA Outside of Containment 1
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- 1. An Active Protection is presented by a valve which needs to close on demand.
- 2. A Passive Protection is presented by a valve which needs to remain closed.
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Page 19 Calculation No. NSD-023 G
3.0 Inputs and Assumptions This calculation addresses the applicable input considerations from WE-100, Table 1 and are summarized below and in Section 7. DE&S EDRs (CRs) were reviewed for influence on the calculation. ANO-2 Safety Evaluation Report (SER) conditions / limitations have not beeen reviewed as it is the responsibility of ANO-2.
In addition to Reference 1, numerous plant specific documents are reviewed (see Section 7 references); the following are key inputs to this analysis:
i ANO-2 IPE (Reference 2) is used to assess importance and unavailability of systems, trains, accident initiators, and accident sequence types. The IPE also contains information on systems operation, dependencies, and spatial consequences (e.g., intemal flooding initiators).
The ANO-2 P& ids, Isometrics, and Plant Design Drawings (References 3,4, and 5) are utilized to identify piping locations.
ANO-2 Documents (References 6 through 9)
ANO-2 Internal Flooding Study (Reference 10) f%
(,1 3.1 IPE Review i
The ANO-2 IPE (Reference 2) is used to evaluate the importance ofinitiating events, systems, and spatial locations affected by potential pipe leaks and/or failures.
i Core damage frequency depicted in the ANO-2 IPE is approximately 3.4E-5/yr. Table 2-1 shows the contribution of accident initiator types as well as conditional core damage probability (CCDP) which provides an indication of mitigation capability for each initiator.
The following summarizes the review results:
LOCAs outside containment, internal floods, and ATWS sequences are screened from the IPE as contributing less than or equal to IE-6/yr.
Loss of DC bus 2D01 or 2D02 are important. These events prevent fast transfer of AC power, cause blackout at one bus, loss of main feedwater, and once-through cooling is unavailable (ECCS vent valves unavailable). This is combined with failure of the unaffected EFW train and/or operator failures to recover AC power to cause core damage.
Loss of AC bus 2A3 or 2A4 are imponant. These events result in blackout at one bus and loss of main feedwater. This is combined with operator failures to realign affected DC to another AC bus and/or control EFW flow with realignments or local actions.
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Page 20 Calculation No. NSD-023 IPE Table 3.5.4-3 summarizes the importance of operator actions and equipment. Operator actions to align offsite power, realign AC power, realign DC power, and trip RCPs are most important. Batteries, EFW train A, and diesel generators are important equipment.
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O ano_swl. doc 3/2&98
Page 21 Calculation No. NSD-023
(
)
3.2 Safety Functions Each critical safety function is considered when determining the number of available mitigating trains in the consequence evaluation. Figures 3-1 A & B summarize the ANO-2 IPE (Reference
- 2) success criteria as a simplified diagram. Reactivity control and pressure boundary integrity functions are not shown in the figure, but are discussed below. The following summarizes how these functions and others are treated in the consequence evaluation:
Reactivity Control - this function is not explicitly included in the consequence evaluation.
Although this function is required immediately upon demand to protect the core, a pipe failure is judged more likely to cause a reactor trip than to prevent a reactor protection system success (this function is fail safe, de-energize to actuate). Also, it is judged unlikely that a pipe failure would immediately impact actuation of turbine trip, safety injection, or EFW. The most likely scenario could be an independent failure of RPS (unavailability on the order of IE-5; a medium consequence without other mitigating capability) and failure of safety injection or EFW due to the piping failure. Since such failures due to pipe failure are likely to lead to " Medium" or higher consequences due to impact on other safety functions, the reactivity control function is not explicitly evaluated.
RCS/ Core Heat Removal & Inventory Control - these functions are included in the simplified f]
success diagram as shown in Figures 3-1 A & B. For transients, the steam generators with feedwater or emergency feedwater or auxiliary feedwater can provide the heat removal V
function. Inventory control is assumed not to be a primary concern unless there is a challenged and stuck open pressurizer safety valve or a seal LOCA (RCS integrity function).
If the steam generators can not provide the necessary heat removal, the HPSI system in combination with pressurizer vent paths can provide heat removal and inventory control (once through cooling). For this success path, transfer to containment sump recirculation and heat removal with containment spray is required. As shown in Figure 3-1B, the success criteria changes for LOCAs since inventory control becomes the primary concern. A stuck open pressurizer safety or a seal LOCA (RCS integrity function failum) is assumed to be a medium LOCA as modeled in the IPE.
Containment Performance - To maintain the consequence category determined from the above functions, at least one containment barrier must be available or there must be margin in the number of available mitigating trains as described in Section 2. Otherwise, the consequence category is adjusted accordingly.
I Table 3-1 summarizes key functions, systems, and pump trains shown in Figures 3-1 A and B.
The table also explains the backups trains assumed in the analysis.
Loss of the service water system (in part or in total) presents special impacts relative to the loss of other systems in that many mitigating systems are dependent upon service water for equipment q
U>
cooling requirements. Table 3-2 summarizes the functional dependencies of the various loads supplied by the service water system. As shown, loss of the service water system can impact ano,,,swl. doc 3/26/98
Page 22 Calculation No. NSD-023
()
mitigating equipment including the ECCS system, the emergency diesel generators, the EFW system as wel! as other components such as the CCW and FPC heat exchangers. Depending on where the pipe break is assumed to occurred, the service water failure can result in a loss of supported equipment due to loss of equipment cooling (e.g. 2E-53A, HPSI Pump Cooler), area cooling (e.g. 2VUC-7A, Charging Pump Room Cooling), inventory supply (e.g. service water to EFW pump suction). Typically, each train of mitigative equipment is supplied by its corresponding train of service water. As depicted in Table 3-2, some equipment can be supplied by either service water header. These components and/or systems can be recovered by alignment to the other train. Also, as depicted in Table 3-2, a loss of a single header can impact a whole system (e.g., ACW) or an additional pump train (e.g., HPSI C) depending on which header is aligned.
In the IPE, HPS! and containment spray pump cooling (service water dependency) are only required in the containment sump recirculation mode of operation (Reference 2, pages A-20 and A-45). LPSI pump seal and room cooling (service water dependency) is required during all modes of operation (Reference 2, page A-52). Also, EFW pump room cooling is necessary based on Reference 2 (page A-33). Other important service water dependencies include emergency diesels, containment cooling units, shutdown cooling heat exchangers, component cooling water (CCW effects reactor coolant pumps, feedwater, and condensate), auxiliary cooling water (ACW effects turbine and assumed to make power conversion system unavailable),
fuel pool cooling, and other room cooling loads.
O LJ 3.3 Plant Level Assumptions Engineeringjudgments are included and discussed throughout the analysis; the following are considered to be key plant level assumptions and judgments:
- 1. Pipe failure can occur at anytime; three configurations are defined as shown in Table 4-1.
These are normal (operating or standby), test, and accident demand. This table also summarizesjudgments and assumptions regarding which configurations are most important.
If pipe failure does not cause a direct initiating event, it is assumed that pipe failure occurs during the accident demand configuration, if applicable. This assumes pipe failure occurs during the most conservative exposure time and accounts for the higher stress placed on the operators with resultant delay in operator response.
- 2. Pipe failures in moderate energy lines (<200 F and <275 psig) are assumed to be large. This analysis goes beyond the design basis by evaluating the consequences of unisolated large breaks (i.e., flooding) even though they are considered less likely in moderate energy lines.
Smaller breaks would allow more time for the flooding impacts to occur. Most studies would consider such events almost incredible.
- 3. The valve arrangement in Room 2084 and the failure of fire doors into Room 2073 are assumed to preclude flooding of the ECCS valves in Room 2084. Some of the ECCS valves m
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appear to be close to the floor (i.e.,2 feet above El 360), but their motor operators are l
judged to be a few feet higher. Sprays could impact some valves, but there are a number of ano_swl. doc 3/26/98
I Page 23 Calculation No. NSD-023 (g)
HPSI supply valves and the containment spray valves are separated such that there should always be a discharge path for these systems. Also, flooding to a level of 3 to 5 feet in a room is assumed to fail the door and drain the room (doors open out of rooms toward Room 2073).
- 4. MCCs at El 354 (Room 2073) and El 335 (Room 2040) are rssumed to fail if water accumulates to a height of 6 inches at the MCCs. At El 54, there is a large grated opening to El 335 on the west end of the building. Thus, it is assumed that breaks in this analysis scope can not accumulate 6 inches at this location. It takes a significent time to flood to a level of 6 inches at El 335, but it is assumed that failure to isolate results in MCC failure. The main service water headers are located at El 335; for these breaks MCC 2B52 impacts are assumed to occur whether isolation is successful or not; this is conservative.
- 5. This analysis assumes that filling of an EFW pump room (CST or service water as the source) will not cause gross structural failure of the room or door. The watertight doors are very heavy and open into the rooms.
- 6. The IPE internal flooding study identifies impacts in rooms from cable terminal points. Since most junction boxes, terminal boxes, etc. noted during the walkdown are at least a few feet off the floor, these impacts are ignored in the analysis. Also, junction boxes appeared to be tight and scaled, therefore, even if water reached them, an electrical fault appeared unlikely.
- 7. No credit is allowed for isolation of ECCS Room ventilation penetr.itions. Isolation could prevent flood propagation into or out of the ECCS rooms. These ventilation openings auto
("')
close on a safety injection signal and annunciator response procedures for room flooding direct operators to close these penetrations.
- 8. The IPEEE (external hazards analysis) assessment neglects (1) the potential impacts of relay chatter from relays with unknown capacity (possible optimism, although this is scheduled to be resolved), (2) an improvement if the seismic capacity of EDG tanks is increared, and (3) a detailed review of fire scenarios (not provided in the IPEEE). These are not ju Jged to significantly impact the analysis results.
- 9. This analysis is based on a walkdown performed on the EFW, containment spray, and feedwater systems. These same areas of the plant also contain service water, however, there are senice water piping areas which have not been walked down by the analyst. Also, the focus of the previous walkdown was not on service water piping. An ANO-2 walkdown of the service water system (Reference 20) and their review of this evaluation are used to assess spatialimpacts and propagation.
- 10. The consequence analysis in Appendix A includes greater than 4 inch nominal diameter piping. The analysis of piping equal to and less than 4 inches is based on a review relative to the larger piping results to ensure that the larger piping is bounding. Relative to this review, 4 inch piping and less isjudged small enough such that flow diversion does not cause a loss of a service water header initiating event (i.e., there is significant time to locate and isolate the leak, Reference 20). Also, propagation is assumed successful such that significant accumulation does not occur (e.g., floor drains and under doors) causing failure of mitigating
[jD systems.
x ano_swl. doc 3/26/98
1 Page 24 Calculation No. NSD-023
- 11. Service water pipe breaks down stream of 2CV-1530-1 and 2CV-1531-2 (common supply to i
CCW), including the common return piping, is assumed to cause flow diversion to both service water headers until isolated. The headers upstream of these valves are treated as independent. Service water header connections (greater than 4 inch) on elevation 335 (Room 2040) are treated as part of the header unless there is an isolation valve or some other reason to separate piping into another segment. There are potential conservative and non
(
t conservative impacts associated with these assumptions, but they are considered reasonable.
- 12. Loss of fuel pool cooling is possible, but neglected in the analysis. There is significant time to recover heat removal ud/or provide makeup before fuel damage.
- 13. Service water pipe break events are assumed to be isolated eventually (e.g., failure to isolate is assumed to fail ECCS by flooding El 317, but not fail EFW, etc. at El 335 and above).
Flow diversion failures are assumed to fail EFW from loss of room cooEng which is conservative (EFW could be successful without cooling long enough to allow additional l
recoveries).
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d Page 25
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Calculation No. NSD-023 o
Table 3-1 Assumed System & Train Backup System / function / train Trains Explanation MFW (gate B02) 1 Given no MSIV isolation or loss of PCS initiator, main feedwater is treated as at least I train.
SDBCS/Cond 0
Recovery with steam dump bypass control and condensr.te has not (gate P300) been credited in the analgs.
EFW (gate Q001) 1.5 Common cause is assumed to be dominated by 4 trams of steam generator supply paths.
EFW (gate Q005) SLB 1.5 Same as above Motor EFW l
ne pump trains are assumed to dominate unavailability. Here are multiple injection paths to steam generators and they can be locally opened. Normally open suction to CST and auto switchover to service wateris reliable.
Turbine EFW 0.5 The pump trains are assumed to dominate unavailability. There are multiple injection paths to steam generators and they can be locally openeu. Normally open suction to CST and auto switchover to service water is reliable.
AFW 0.5 Highly dependent on operator actions & CST is required.
OPER 1
He "Once Brough Cooling" path depends on OPER-2 (SE-3) and can be assumed to be I train as long as there is a success path available in Figure 3-1 A.
HPSI(gate H001) 1 OPER assumed to dominate.
HPSIA 1
Pump train dominates with multiple injection paths.
HPSIB 1
Pump train dominates with multiple injection paths.
Requires operator action.
HPSIC Pzr vent (gate R001) 1 Redundant series MOVs.
Recire (gate H003) 1 OPER assumed to dominate.
Recire A 1
Sump MOV must open and other MOVs close.
Recire B 1
Sump MOV must open and other MOVs close.
Contamment Spray 1
OPER assumed to dominate.
(gate Y001)
Pump and discharge MOV dominate.
Pump and discharge MOV dominate.
This is a check on the conditional probability of a transient induced Integrity (gate Q01 A)
LOCA. Unavailability is based on gate QO2B=1 Not used in analysis.
LPSI(gate L001)
Pump and discharge MOV dominate. Not used in analysis.
LPSI A Pump and discharge MOV dominate. Not used in analysis.
LPSIB Not used in analysis.
SDC (ga*e LOO 2)
Not used in analysis.
SIT (gate C0001)
AU ano._swl. doc 3/26/98
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Page 29 l
Calculation No. NSD-023 Figure 3-1 A Simplified Success Criteria for Transient MFWor SDBCSK.ond N
I Fw M Success
~ECCS HPSIA*
CSS *A*
-v
-+
s y,,,,
g,ci,,
oPER HPSl *B" LToP HPSl *B*
CSS *S*
_9
_9 g
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R.cire HPSl *C-9 The above simplified diagram applies to a transient with the power conversion system (PCS) initially available. The containment cooling function is not shown for the once through cooling function because most of CSS piping is required to support recirculation function. Containment coolleg is credited as a train for breaks that can be isolated, allowing HPSI and LPSI success.
.O ano_swl. doc 3/26/98
1 Page 30 Calculation No. NSD-023 Figure 3-1B Simplified Success Criteria for LOCAs Main Feedwater HPSl *N Y
Motor HPSl'A" CSS"N Y
-Y l
. HPStalr' CSS "B" l
~
(1)oPER Y
SDBCS ECCS s->
wm SDC OPER Recowry LToP
+
~
l we (1) If main feedwater or EFW or AFW is successful, the operators can depressurize with steam generators and remove sufficient heat to preclude the need for recirculation and containment heat removal. The containment cooling function is not shown because most of CSS piping is required to support recirculation function and medium LOCA is assumed (SLOCA success path is not used in the analysis).
HPSl *N LPSI"N HPSl"N CSS"N (1)
Recire MLOCA HPSl *B*
g s
LLOCA LPSI "B" HPSI "B" CSS *B" g
g (1)
Recirc HPSI "C" l
(1) LPSI is only required for Large LOCAs (LLOCA) and SITS success is not shown (assumed to be more reliable than LPSI). The containment cooling function is not shown because most of CSS piping is required to support recirculation function.
Containment cooling is credited as a train for breaks that can be isolated, allowing HPSI and LPSI success.
O ano_,swl. doc 3/26/98
1 Page 31 Calculation No. NSD-023 (J3 4.0 Analysis 4.1 Configurations & Pipe Runs An important input to the consequence evaluation is the system configuration under which piping
)
is assumed to fail. The following system configurations are used in the evaluation. For these configurations, the plant is assumed to be at-power.
- 1. Normal (operating or standby)
- 2. Test (periodic testing applies)
- 3. Demand (real demand due to plant trip or accident)
The configuration can influence piping loads, piping degradation mechanisms, the probability of failure (demand 4 time dependent exposure), and the probability of detecting and isolating the failure prior to significant propagation and/or impacts. It is assumed that pipe failure occurs during an accident demand if the pipe failure does not cause an initiating event and does not see service flow during normal power operation. This is conservative in that it increases exposure time and reduces human reliability in response to a pipe failure m comparison to the ' Normal" and " Test" configurations. This is explained further in Section 2 and Figure 2-1. Table 4-1 documentsjudgments made in the consequence analysis relative to applying the above 1
l configurations.
The follow'mg summarizes how piping runs and configurations are identified:
- 1. The system P&ID, isometrics, and plant design drawings (References 3, 4, and 5) are reviewed to determine the location of analyzed piping within the plant and associated piping connections (e.g., CST, RWT, reactor coolant system, Lake). Connections to normal operating systems are considered as having a high potential for causing an initiating event as well as spatialimpacts.
- 2. The IPE, including the internal flooding study (References 2 and 10), is reviewed to determine the importance of spatial locations (i.e., location of critical equipment),
propagation paths between plant locations, as well as detection & isolation capabilities.
- 3. Based on the above, the system piping is divided into piping runs based on spatial location and an initialjudgment as to initiating event potential and the consequences if an unisolated pipe failure occurs. In addition, the applicable configuration is detennined (e.g., normal operation or demand). Location designators in the IPE internal flooding study are used in this analysis. Generally, a new piping consequence ID is defined for each location or an additional consequence ID is defined when the ceasequences differ within a location (i.e., isolation capability changes). In some cases, the piping comequence ID contains piping in more than one location when the consequences do not change; O
ano_swl. doc 3/26/98
I Ps 32 I
Calculation No. NSD-023
")
The results are provided in Appendix A for the major piping (greater than 4 inch nominal pipe diameter) and developed throughout this analysis.
Other Modes of Operation The consequence evaluation is an assessment assuming the plant is at-power. Generally, the at-power plant configuration is assumed to present the greatest risk for piping since the plant requires immediate response to control reactivity, heat removal, and inventory control; the plant is critical, at higher pressure, and temperature in comparison to shutdown operation. The '
potential importance of piping during plant shutdown is evaluated here to establish confidence that no gross misjudgment is made in the consequence assignment. This evaluation concluded that power operation should be bounding for the service water system.
Pipe segments that are already a "High" consequence from the evaluation at-power need not be evaluated for shutdown. Those that are already " Medium" require confidence that High would not occur due to shutdown configurations. However, a " Low" consequence for power operation requires more confidence that a High woald not occur and some confidence that a Medium consequence would not occur. Taking this into account, a review & comparison of system consequence results for power operation versus potential consequence during shutdown operation is conducted.
Other observations about shutdown operation considered in this review include the following:
(]
During shutdown, mitigation systems are not automatic and require manual actuation. EFW G
e is automatic until cold shutdown (Mode 5, <200 F) an='. ECCS actuation is no longer automatic when RCS is <361 psia in Mode 4 (2102.e.
30 " Plant Cooldown").
However, Entergy's outage management philosophy m ask management guidelines, and procedures provide assurance that loss of SDC ' '
niected and mitigated (e.g.,
2203.29, Rev 9 " Loss of Shutdown Cooling").
Unavailability of mitigating trains is higher due to planned maintenance during outages.
However, guidelines and procedures assure suflicient redundancy and account for higher risk configurations (e.g., mid-loop) which requires extra redundancy and/or contingencies (e.g.,
2R12 Shutdown Operations Protection Plan, May 8,1997).
For the majority of piping, the exposure time associated with operation in a shutdown j
configuration is on the order of 0.1/yr. The frequency of being in a more risk significant j
configuration could be even lower depending on the system and function being evaluated.
For the majority of standby piping, the frequency of challenging important mitigating systems isjudged to be on the same order of magnitude or lower.
The reactor is shutdown, depressurized, and decay heat is lower than for at-power operation.
)
The reactivity control function is not a concern because the rods are inserted. Re-criticality during shutdown is unlikely and not judged to affect the present ranking. The inventory makeup (safety injection) function is considered the most important function during
(
shutdown, given a pipe break occurs during shutdown causing loss of SDC. Loss of service water during shutdown is much less likely to cause core damage because the recirculation ano_swl. doc 3/26/98
Page 33 Calculation No. NSD-023 function (which requires pump cooling and heat removal) would be needed much later in time, if at all. In other words, if the steam generators and other decay heat removal systems are not available, makeup to the core could be considered a success, allowing significant time to consider heat removal.
Decay heat is lower during shutdown such that the time for recovery of shutdown cooling or o
inventory makeup is usually longer. Thus, even though equipment may require manual actuation and may also be in maintenance, there is time for recovery. Even LOCAs (considered less likely due to reduced pressure and temperature) would exhibit much less severe environmental conditions (e.g., hot or warm water versus steam) until decay heat starts to heatup reactor after loss of SDC.
l That portion of service water supplying LPSI heat exchangers that is in standby during power operation and operates in the SDC mode during an outage is judged to present the most important ccnfiguration change requiring further evaluation. Loss of SDC is an important l
initiating event during shutdown.
Most of the major service water pipe segmeas are in the "High" or " Medium" consequence category from the power operation evaluatir,a. The service water piping to the SDC heat exchangers is a " Medium" consequence cased on a LOCA demand during power operation.
l l
Failure of this piping during shutdown would cause a loss of SDC initiating event. Detection would occur as during operation and flooding could impact ECCS at El 317. Service water piping does not cause a LOCA condition and there is time for isolation and recovery. If the
+(
reactor coolant system (RCS) is closed, a steam generator can be used or a pressurizer vent with l
reactor makeup is necessary. If the RCS is open, almost any makeup source can satisfy boil off.
CCDP for loss of service water is judged to be on the order of IE-4 or less (Medium) durir.g shutdown.
In summary, most SW piping already causes an initiating event during power operation and is in the "High" or " Medium" category based on power operation. The SDC pipe seg,ents l
challenged as part of the recirculation heat removal function are a " Medium" consequence and judged to be similar or less during shutdown when an irdtiating event could occur. A more detailed risk assessment of shutdown configurations would be needed to support a " Low" consequence for the piping.
- External Events The consequence evaluation is an assessment utilizing design basis information and the plant PRA for internal initiating events. Pipe breaks cause the same initiating events in the PRA and their frequencies in the present evaluation is higher than the frequency of fire and seismic events.
However, these low frequency events beyond the design basis have potential common cause
. effects that could possibly affect the importance of piping. Because of this, the importance of
. piping during extemal events beyond the design basis is assessed here to establish confidence that no gross misjudgment is made in consequence assignment. This evaluation concluded that the present analysis piping consequences bound external events.
Pipe segments that are already a "High" consequence from the evaluation need not be evaluated for external events. Those that are already " Medium" require confidence that High would not ano_swl. doc 3/26/98
Page 34 Calcula1on No. NSD-023 occur due to external events. However, a " Low" consequence for power operation requires more confidence that a High would not occur and confidence that a Medium consequence would not occur. Taking this into account, a review & comparison of system consequence results versus potential consequence during external events is conducted.
The following observations can be made, in general, for all external initiators:
For piping which is assumed to cause an initiating event in the present analysis, external o
. initiating events should not have an impact on pipe importance. The frequency of the initiator is already 1.0 in the present analysis. The frequency of an external event causing a pipe failure
~ is low and the probability of an external event simultaneous with the pipe break is also low.
Based on the above, it is expected that piping in mitigating sptems that respond on o
" Demand" to external initiating event challenges are more likely to be affected. The frequency of challenge and impacts on redundant mitigating functions due to the external initiator are considered.
The ANO IPEEE was reviewed; the results are summarized for each hazard below. The following summarizes the review for each of the major hazards (seismic, fire, and other):
Seismic Challenges - Except for the emergency diesel fuel tank A & B (2T57A & B), other structures, systems, and components in the seismic safe shutdown list screened at the 0.3g HCLPF (high confidence low probability of failure). Some relays with unknown capacity are not resolved and are not evaluated in this review. The calculated HCLPF for the two tanks is 0.2g. It can be concluded that seismic loss of offsite power (HCLPF < 0.2g) and seismic Qilure of the tanks would result in an important accident scenario (station blackout with recovery unlikely).
The potential effects of seismic initiating events on consequence ranking is assessed by considering the frequency of challenging plant mitigating systems and the potential impact on the existing consequence category. The followirig summarizes this assessment:
Piping in the analysis scope will have a capacity much greater than the 0.3g screening value and is not considered likely to fait during a seismic evnt.
Most major piping is already assumed to cause an initiating event in this analysis. The frequency of an earthquake induced pipe failure in these systems is less than assumed in the present analysh. Also, the likelihood of a simultaneous seismic event during or after a pipe break is low.
. Reactivity controlis unlikely to be afrected by seismic events because loss of offsite power (usually the seismic limiting component with any consequence) will de-energize and drop control rods. The earthquake is more likely to cause a scram rather than prevent it. A very large earthquake could cause mechanical failure of the core and/or prevent rods from entering the core. However, such a low probability event would likely impact most functions due to equipment failures, causing core damage. The importance of the piping becomes O
irrelevant at this point and it is a low probability event.
ano_swl. doc 3/26/98
s i
Page 35 l
Calculation No. NSD-023 With regard to mitigation, the most likely scenario would be loss of offsite power due to the e
seismic event. The seismic capacity of offsite power has been found to be limiting, both with respect to seismic capacity and its impact on the plant; it causes the unavailability of feedwater, main condenser, and all equipment dependent on normal AC power. It also challenges emergency diesels (usually less reliable than the numerous trains of mitigating systems they support). Based on a typical fragility for LOSP (Reference 13), a HCLPF of about 0.lg is assumed. This frsgility when combined with the seismic hazards developed for the ANO site (References 14 and 15) indicate the unconditional frequency of a seismically
~
induced LOSP is less than IE-4/yr. Since the rervice water analysis includes initiating event challenges on the order of IE-2 or greater, the seismic challenge is judged to be enveloped by l
the present analysis. Note that IE-4 alone provides the basis for a " Medium" CCDP.
With regard to the impact on mitigation backup trains, the most likely scenario would be seismic loss of offsite power (<1E-4) and failure of one service water supply to an emergency I
diesel on demand (1.0 assumed). The unavailability of the backup service water and diesel l
train is between 0.1 and 0.01. Thus, the total CCDP for this piping would be <1E-5.
Fire Challenges - The total estimated core damage frequency due to intemal fires is 3.5E-5/yr in the ANO IPEEE. Fires in the turbine building (50%), cable spreading room (17%), diesel corridor (17%), intake stmeture (8%), control room (5%), and auxiliary building extension (3%)
dominate risk. The IPEEE report did not provide sufficient information on the dominant scenarios regarding which systems failed, what the initiating ever.t is, and which mitigating O
systems are available. Typically, important fire scenarios are those that impact support systems (e.g., because of their comwr cause effect) and/or multiple mitigating systems. Similar to seismic events, fires usually do not impact reactivity control nor cause LOCAs unless it is due to a stuck open reliefvalve.
Similar to the seismic analysis, the frequency of mitigating system challenges from 6res is judged to be less than assumed in the present analysis. For example, fires causing loss of offsite power and challenging SW to the emergency diesels should be on the order c IE-2 or less, otherwise c
we would see such events occurring in the industry. Ifit is assumed that one SW train fails on demand, the total CCDP would be less than IE-4 (unavailability of backup diesel and turbine driven EFW is at least IE-2). This format is similar to seismic in that loss of offsite power is assumed to be an important challenge because it makes feedwater and the main condenser unavailable (AFW is also assumed unavailable). Note that fires are not assumed to cause a LOCA (pipe break) which is a possibility for seismic.
Other Challenges - these hazards are screened in the ANO IPEEE and are assumed not to influence ranking. The frequency of challenging mitigating systems due to these other external challenges is comparable or less than considered in the seismic and fire analysis above. Also, the likelihood ofimpacting mitigating systems is less. The discussion of seismic and fire is assumed
, to envelope.
Based on a review of the ANO-2 external event information, the RI-ISI results are not expected to change significantly, ano_swl. doc 3/26/98
Page 36 Calculation No. NSD-023 O
.2 Spatial Arrangement and Walkdown 4
o 4.2.1 Spatial Arrangement The location of piping, the propagation paths from that location, the spatial impacts from the pipe failure, and propagation (i.e., sprays, flooding) are necessary to assess direct impacts (i.e.,
initiating event potential) and indirect impacts (i.e., flooding) in the consequence analysis. System P& ids, Isometric drawings, and the IPE internal flooding study are key inputs in assessing these impr. cts for each system. A plant specific walkdown (Reference 20) was conducted to confirm these spatialimpacts.
Figures 5-1 through 5-6 provide simplified system diagrams and summarizes the location of l
system piping within the analysis scope. Plant locations, as defined in the IPE internal floong l
study, are used in the analysis. These locations are summarized in Table 4-2 and described below relative to propagation, detection (only spatial detection; system detection mechanisms are discussed later for each system), and potential impacts. Table 4-3 also summarizes the analysis of piping greater than 4 inches, its location, and the resulting consequence from Appendix A.
i
{
l Containmen_1 Service water supplies the containment coolers, however, flooding is containui and there is no l
success path electrical equipment located inside the containment. Detection inside containment l
includes containment sump level and there is a low service water flow alarm in these paths l
(Reference 8).
i Intake Stmeture The service water pumps, header 1 & 2 cross-tie MOVs, and the ACW supply isolation MOVs I
are located here. There are grated openings in the floor to return water to the intake bay, L
preventing flooding of equipment (References 7, 8, and 20).
l l
Turbine Auxiliary Buildina & Main Turbine Buildine (TAB. TB)
Service water to CCW coolers and to tower / pond does communicate with these areas. There is no safety equipment in these locations and the more likely propagation is into the turbine building. No spatial impacts are assumed in this area except possibly the power conversion system (PCS). Potential impacts on the PCS are not evaluated because errangement drawie (References 2 and 5) and Reference 20 indicate the turbine build!r,g area is very large, precluding floodingimpacts on PCS.
ReMor Auxiliary Building Elevations 386 372. A 368
- Piping within the scope of this analysis supplin room coolers and the emergency diesel (EDG) jacket hea, xchangers. The main piping ercers the EDG rooms (Rooms 2093 and 2094) and supplies thz antrol room emergency candensing units. The control room and critical electrical equipment ( -1.ated at these elevr.6ons. The emergency diesel generators are located at El 369 with surrounding rooms at El 3?4-6 and 372. A water tight door is provided for access between EDG rooms and the corrido: entrance to the north room. There is a 5 inch curb at the south ano_sw1. doc 3/26/98 -
l Page 37 Calculation No. NSD-023 room corridor entrance. Each EDG room have at least three floor drains, an intrusion alarm and float type switches that alarm in the control room (Reference 20).
' Reactor Auxiliary Buildinn Elevations 354. 335. and 317 Most of the major piping within the analysis scope is located at these elevations. Propagation from elevation 354 to elevation 335 is easily accomplished by grating on the west end of the building corridor (Room 2073). The auxiliary building elevator and east stairway 2001 (2149-B) also provide propagation paths. Propagation from elevation 335 to elevation 317 is through east stairway 2001 (2149-B). Both elevations have floor drains that propagate to El 317. Specific rooms are described below in greater detail.
Room 2081 - North Pinine Penetration Room at El 354 and 335 (RAB 2081-HIO In this analysis, Room 2081 includes Room 2048 which is the designated room for El 335.
Service water return headers from CCW and ACW (2CV-1543-1 and 2CV-1542-2 are located several feet off the floor) pass through this room. Containment cooling service water train B supply and return piping (2CV-1510-2 and 2CV-1513-2 are located several feet off the floor) l-also pass through this area. Propagation is down through the spiral staircase and grating to l
elevation 335. There is a door with no latch (a requirement of high energy line break analysis) to a large corridor (RAB 2040-D). Also, there is a door at elevation 354 into a stairway which is E
tight and opens into the room. Continued propagation and detection at El 317 is the same as described below for Room 2040.
Both of the main feedwater lines enter the containment through the north piping penetration room which consist of two levels connected by a spiral staircase from floor elevation 335. Two EFW header supply lines, including MOVs, to steam generator B (one from each EFW train) are also located in the north piping penetration room. Header MOVs and check valves are located in this room above elevation 354. Test return valve 2CV-0798 is located about 5 feet above El 335.
Eqqry 2084 - Upper South Pioine Penetration Room at El 360 (RAB 2084-DD)
In this analysis, Room 2084 includes adjoining rooms that connect to Room 2084 discussed i
belo u Containment cooling service water train A supply and return piping (2CV-1511-1 and 2CV-1519-1 are located at about El 362) pass through this area. Propagation would be out the doors into the corridor (Room 2073) at El 354. Propagation from elevation 354 to elevation 335 (Room 2040) is easily accomplished by grating on the west end of the building corridor (Room 2073). The auxiliary building elevator and east stairway 2001 (2149-B) also provide propagation paths. Continued propagation and detection at El 317 is the same as described below for Room j
2040.
Two EFW header supplies to steam generator A (one from each EFW train) are located in this room. Header MOVs and check valves are located in this room at about El 365. Both containment spray discharge paths are in this room where they penetrate the containment building (containment spray discharge MOVs are located at about El 362).
O ano_swl. doc 3/26/98
Page 38 Calculation No. NSD-023 A
(
! Other imponant valves located in this room include normally closed HPSI header supplies and normally closed LPSI supplies to the RCS hot and cold legs. The motor operators arejudged to be high enough off the floor to preclude impacts due to flooding.
Room 2055 - Lower South Pipinn Penetration Room at El 335 (RAB 2055-JD In this analysis, Room 2055 includes connected Room 2031. Containment cooling service water train A supply and return piping pass through this area. EFW section piping from the Unit 1 CST passes through this area. EFW discharge piping to steam generator A, including normally closed (fail close () test return valve 2CV-0714-1, is located in this room. Containment spray discharge piping also passes through this room. Propagation is through a door into Room 2040 6t El 335.
Continued propagation and detection at El 317 is the same as described below for Room 2040.
Other imponant valves located in this room include normally open HPSI train A & B supply to the cold legs and the LPSI locked open supply from the heat exchangers and locked open low pressure injection supply. The motor operators are judged to be high enough off the floor to preclude impacts due to flooding and the valves are in their normal safe position (open).
Room 2073 - General Access Area at El 354 (RAB 2073-DD)
In this analysis, Room 2073 includes several connected smaller rooms. Service water supply and return piping for EDGs, room coolers, and fuel pool heat exchanger pass through this area.
Propagation to elevation 335 (Room 2040)is easily accomplished by grating on the west end of p
the building corridor. The auxiliary building elevator, floor drains, and east stairway 2001 (2149-V B) also provide propagation paths. Continued propagation and detection at El 317 is the same as described below for Room 2040.
The most important component in this room is MCC 2B62 which contains breakers for key train B valves. These valves include normally closed containment spray train B supply (2CV-5613-2),
normally closed train B containment sump recirculation (2CV-5650-2), normally closed HPSI hot leg 2 supply (2CV-5102-2), one of four normally closed HPSI train B cold leg supplies (2CV-5076-2), normally open HPSI train B orifice bypass (2CV-5104-2) and one of two normally closed LPSI train B cold leg supplies (2CV-2077-2). Also, train B of CVCS, shutdown cooling, and diesel room ventilation are powered from this MCC.
The floor area is large, there are several floor drains, and it takes at least 6 inches of water to fail the MCC, which is highly unlikely due to the easy propagation to El 335 through the grating at j
the west end of the corridor. The door opens out of Room 2084, thus, limited water can collect l
before gross failure of the door.
There are service water valves located in this room, b' heir motor operators are more than a foot off the floor where again flooding is not expects N reach.
Room 2040 - General Access Area at El 335 fRAB 2040-JD In this analysis, Room 2040 includes several connected rooms, including tank room 2054 which j
(g) contains RWT suction piping and MOVs to containment spray. Both main service water supply and return headers run through room 2040. Propagation from room 2040 is into stairwell 2001 ano_swl. doc 3/26/98
Page 39 Calculation No. NSD-023 (RAB 2149-P.) ed down to elevation 317 (RAB 2006-LL and 2011-L). Detection is provided by the auxiliary building surp (El 317) high level alarm (annunciator 2K15) in the control room
" AUX BLDG SUMP LEVEL HIGH" (Reference 11). Corrective actions for flooding include ensuring that ESF pump rooms are isolated. EFW pump rooms are protected from flooding as described below (Rooms 2024 and 2025).
The most important component in this room is MCC 2B52 which contains breakers for key valves. These valves include normally closed containment spray supply train A (2CV-5612-1),
normally closed train A containment sump recirculation (2CV-5649-1), normally closed HPSI hot leg 1 supply (2CV-5101-1), two of four normally closed HPSI train A cold leg supplies (2CV-5035-1 and 2CV-5075-1), normally open HPSI pump B & C recirculation (2CV-5128-1 &
2CV-5127-1), normally open HPSI train A orifice bypass (2CV-5103-1), and one of two normally closed LPSI train A cold leg supplies (2CV-2037-1). Also, train A of CVCS, shutdown cooling, and diesci room ventilation are affected by this MCC.
The floor area is large, there are several drains, and it takes at least 6 inches of water to fail the MCC (propagation will occur through a stairway and floor drains to El 317). Given the size of the areas, including the intermediate auxiliary building elevation 326, and propagation to El 317, it is unlikely to actually fail the MCC (e.g., 6 inches of water at El 335). Still, the analysis assumes failure of the MCC for the major service water piping due to the potentially very large flow rates.
Room 2024 - Turbine EFW Pumo RAB 2024-JD Service water supply to the EFW pump suction enters this room. EFW steam, suction, and dische e piping associated with the turbine driven pump is located in this room.
EFW pump rooms are at El 329 with access from El 335 through open stairs. The open stair starts about 8 inches above El 335 such that most floods will not reach the EFW pump room doors. Each room has a water tight door (opens into room), an intrusion alarm in the control room, and a float type level switch with an alarm in the control room (Reference 11).
The IPE internal flooding study indicates turbine driven EFW room (page 6-8) contains cable terminal end points that impact both trains of EFW, including its recovery from the control room.
This is identified as MOV 2CV-0707 which is normally open and now is deactivated such that it will not isolate the normal CST suction path. Floods in this room (i.e., not isolated in time) are assumed to fail the turbine driven pump. Since the door is very heavy, opens into the room, and the room is water tight, any leakage out of the room is expected to be within floor drainage capability and have no impact on equipment outside the room.
Room 2025 - Motor EFW Pumo RAB 2025-JD Service water supply to the EFW pump suction enters this room. Suction and discharge piping associated with the motor driven pump is located in this room.
EFW pump rooms are at El 329 with access from El 335 through operi stairs. The open stair starts about 8 inches above El 335 such that most floods will not reach the EFW pump room ano._swl. doc 3/26/98
1 i
Page 40 Calculation No. NSD-023 oC doors. Each room has a water tight door (opens into room), an intmsion alarm in the control room, and a float type level switch with an alarm in the control room (Reference 11).
Floods in this room (i.e., not isolated in time) are assumed to fail the motor driven pump. Since the door is very heavy, opens into the room, and the room is water tight, any leakage out of the room is expected to be within floor drainage capability and have no impact outside the rooms.
Rooms 2006 & 2011 - Gtderal Access & Tendon Access at El 317 (RAB 2006-LL & 2011-LL)
In this analysis, all roms at El 317 except the ECCS rooms discussed below are included as Room 2006 ar.d/or 2011. Service water supply and return piping for shutdown cooling heat exchanps, room coolers, and pump seal coolers pass through this area. Also, piping breaks above El 335 will propagete to these rooms. Detection is provided by the RAB sump level
)
(Reference 11). Service water train A MOV (2CV-1400-1) could be flooded before isolation takes place. There are no impacts on HPSI, containment spray, and EFW in this room.
In order to impact HPSI, containment spray, and LPSI, a very large flood must accumulate in these rooms as described below for Rooms 2014,2007, and 2010.
Rooms 2014. 2007. & 2010 - ECCS A. B. & C. Respectively at El 317 Service water supply and return piping for shutdown cooling heat exchangers, room coolers, and pump seal coolers pass through these areas. In this analysis, Room 2013 is included with 2014, p
Room 2009 is included with 2007, and 2006 includes Rooms 2011 & 2012, as well as several V
pump rooms and the strirway.
If Rooms 2006 & 2011 dood up to about El 328, HPSI"C" room (2010) will be flooded, unless the ventilation openings are isolated (safety injection signal or by operators in Reference 11).
]
Then, if 2006,2011, and 2010 !! cod to about El 329, ECCS rooms "A" (2014) and "B" (2007) will be flooded. Flood propagation into the ECCS rooms is through ventilation openings.
The following summarizes the areas and propagation paths at El 317 based on the IPE internal flooding study:
2 Room Description ft Propagation between 2006/2011 RAB 2006-LL General Access 3316 El 317 RAB 2011-LL Tendon Gallery 240 El 317 RAB 2010-LL HPSI C 486 about El 328 through ventilation opening RAB 2007-LL East HPSI 2610 about El 329 through ventilation opening RAB 2014-LL West HPSI 2610 about El 329 through ventilation opening Each train of ECCS (HPSI, LPSI, containment spray, and SDC heat exchanger) is in a separate water tight room called the East and West Rooms (2007 and 2014). HPSI C (2010) is in a separate water tight room on El 317 called the Center Room. Each room has ccaductance type
(~')
level detectors that alarm in the control room (Reference 11).
V ano_swl. doc 3/26/98
Page 4' Calculation No. NSD-023 2
The combined area of Rooms 2006 and 2011 is >3500 ft. To flood Rooms 2006/2011 up to El 328 where HPSI C could be affected,287,000 gallons (11 ft
- 3500 ft
- 7.48 gallons /ft') are 2
required. To fill Room 2007 or 2014 up to the ventilation openings requires about 234,000 gallons (12 ft
- 2610 fiz
- 7.48 gallons /ft').
Filling Rooms 2006,2011, and 2010 up to El 329 where Rooms 2007 & 2014 could be affected requires about 359,000 gallons (12 ft
- 4000 ft
- 7.48 gallons /ft'). Assuming that 3 feet of water 2
. is required in Rooms 2007 and 2014 to fail electrical equipment, an additional 116,000 gallons are required (3 ft
- 5200 ft
- 7.48 gallons /ft'). Without a more detailed analysis of floor areas 2
and/or elevations at which HPSI, LPSI, and CSS will be affected, it is concluded that failure to isolate a break will fail all ECCS. For example, the floor area presented in the IPE for the tendon gallery area appears to neglect some floor area.
4.2.2 Walkdown On November 19 and 20,1996, a walkdown was performed at ANO-2 to assess potential spatial interactions. associated with splashing, spraying, and flooding, including propagation paths. The following individuals panicipated in the walkdown and meetings at ANO-2:
O Randy Smith (ANO Consultant)
Jim Moody (DE&S Consultant)
Pat O'Regan (DE&S)
The plant was in an unexpected outage and radiological controls would not allow access to the south piping penetration rooms (Rooms 2084 and 2050) and El 317 (Rooms 2006,2011,2014, 2007, and 2010). However, this is not judged to have an impact on the analysis since spatial questions were answered for these areas during the visit. The focus of the walkdown was in those areas where main steam, main feedwater, EFW, and containment spray piping exists and their propagation paths and impacts. Although this walkdown was not spec!SJ1y conducted for the service water system, the observations are relevant. The following summarizes the walkdown observations:
Main steam piping area (Room 2155) was investigated where main steam and EFW steam.
lines were observed along with the main steam isolation valves and EFW steam isolation and check valves. Although unlikely, it is possible for certain large main steam line breaks to impact both steam lines supplying EFW. The main steam lines are near the common wall with the refueling area (Room 2151), thus, it is considered possible that a very large steam break could damage and/or vent through this siding. There also is siding and doors that open out to an adjoining building roof and stairway (turbine auxiliary building).
O rnei haneiins ana scent reei geei area caeem is>> -a -aikea oe-n. rae erw tea-piping was observed coming vertically down from the steam piping area and into a pipe chase ano_swl. doc 3/26/98
Page 42 Calculation No. NSD-023 which comes out at elevation 335 (Room 2040). This is a very large area and it isjudged unlikely that main steam piping break propagation to this area would impact safety equipment which is mostly located at lower elevations. Also, EFW steam line break isjudged unlikely to impact safety equipment.
- North Piping Penetration (Room 2081) was walked down. EFW and main feedwater valves were identified in the room. Grating and a spiral stair ensures easy propagation to elevation 335 where there is a door with its latch removed (required due to high energy line break analysis) opening out to Room 2040. A door at elevation 354 opens into the room and provides access to a stairwell and the turbine auxiliary building. It would be difficult for floods to access Room 2081 from the turbine auxiliary building side. Propagation into 2081 from 2040 would not affect any equipment as the EFW and MF valves are above the floor.
Elevation 335 (Room 2040) is a very large area containing general access, corridors, and severk! large non safety related rooms. Several floor drains were observed. EFW and containment spray piping is located here, including RWT suction MOVs. The MOVs are located high off the floor in the tank room, protected from floods. Also, the EFW steam admission valve 2CV-0340-2 and 2SV-0205 is located behind a wall and sufHeiently off the floor to be protected. Several rooms connect to this room from elevation'354 (Room 2073) and the piping penetration rooms (Rooms 2055 and 2084) at elevation 335. The most critical component identified in this area is MCC 2B52 which powers several train A components.
O Although the MCC is not near analysis scope piping, it is at the east stairway entrance (the propagation path to El 317). If six inches of water could be accumulated r.t El 335 or if a very large pipe break occurred, it is considered possible that the MCC could fail.
EFW pump rooms (2024 and 2025) at elevation 329 were inspected. The stairs from Room 2040 down to the EFW pump room entrances are protected from flooding because the stairs start about 8 inches off the floor at elevation 335. Also, the pump rooms have a flood protection door that opens into each room. Piping and valves in each room were identified and confinned. Also, the rooms were noted to be water tight; any leakage out of the room (assuming the room fills from a pipe break) would be small and within the capacity of drainage systems. Room flood detectors and floor drains were observed.
Elevation 354 (Room 2073) is a large area containing general access, corridors, and other non safety related rooms. Several floor drains were observed. There is no analysis scope piping located here, but the upper south piping penetration area (Room 2084) will propagate to this room. The most critical component identiSed in this area is MCC 2B62 which powers several train B components. The MCC is not near analysis scope piping and there is easy propagation through grating at the west end of the floor away from the MCC. It appears unlikely that six inches ofwater could accumulate at El 354.
A separate ANO-2 service water system specific walkdown (Reference 20) was conducted by ANO-2 and ABB/CE personnel. Reference 20 was used as an input to this analysis.
O ano_swl. doc 3/26/98
l' Page 43 Calculation No. NSD-023 4.3 Initiating Events There are two types ofinitiating events or demands considered in this analysis:
- 1. The pipe failure causes a direct initiating event.
- 2. When the pipe failure does not cause a direct initiating event, an independent demand for tim system is assessed.
To ensure that direct impacts from initiating events and the unavailability of mitigating systems are properly considered (e.g., impact of support systems and other common cause effects), the L
conditional probability of core damage due to initiating events in the ANO-2 IPE (Reference 2) is assessed. Table 2-1 summarizes consequence categories applied to ANO-2 IPE initiating events when the pipe failure causes such an event. This table is plant specific for ANO-2 and replaces Table 3.1 ofReference 1.
l The following summarizes how initiating events apply for each piping run and configuration in Table 4-1:
- 1. Operating - only the " Normal" configuration is evaluated when the piping is in a normal operating system or the piping is connected to a normally operating system. At ANO-2, pipe f
failure in the service water system results in an initiating event or it is assumed to be the case.
\\
The other configurations either do not apply or are less likely with similar consequences.
l
- 2. Standby - in the case of piping that is normally isolated or does not see normal system flow conditions, pipe failure on demand (i.e., from an independent initiator) is analyzed. Periodic testing during normal operation is assumed to challenge the piping and reduce exposure time for possible pipe failure during a " demand."
- 3. Standby & No Accident Demand - in this case, the pipe is not automatically challenged l
during an accident. The evaluation considers pipe degradation as revealing itself during
" normal standby" and " test" configurations. These are the preferred configurations relative to exposure time for accident demands.
At ANO-2, if pipe degradation reveals itself during " Normal" or " Test" configurations and it does not cause a direct initiating event, detection will occur from the various sump alarms or from visual inspection. An eventual manual shutdown can be assumed based on technical specifications ifisolation and repair of the leak is not quick enough. The exposure time for a real accident demand is lower (e.g., repair time or AOT); if an accident does not occur, human reliability is expected to be high during these configurations. For these reasons, pipe failure is assumed to occur during the " Demand" configuration, if applicable, due to the increased exposure time and higher stress situation for the operators.
O ano_swl. doc 3/26/98
Page44 Calculation No. NSD-023 4.4 Mitigating Capability Mitigating capability is determineu in the analysis utilizing the following:
- 1. After evaluating the total impact on train / systems (direct and indirect impacts, including initiating event, system or train containing the pipe failure, spatial propagation, and draining),
the remaining available mitigating trains (backup trains) from Figure 3-1 are identified.
2.. If pipe failure does not cause an initiating event, the frequency of challenging the system (real.
accident demand) and the exposure time are evaluated. For each normally operating SW train, the allowed outage time (AOT) is 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> (Reference 12). Service water flow rate to the containment cooling units is checked every 14 days; a 7 day AOT with unavailability of a train (Reference 12). The frequency of challenging standby systems when pipe sagment failure does not cause an initiating event is described further below.
- 3. The ability to isolate a break is evaluated and credited, if feasible.
- 4. When evaluating the consequences from "no isolation" (either not possible or failure to isolate), the probability ofisolation failure is assessed. Based upon the likelihood of detection and the time available for the operator response, usually an equivalent backup train is assumed in the analysis.
The consequence evaluation addresses the potential of both successful isolation and unsuccessfi'!
isolation of the break. The reliability of detection and isolation depends on plant configuration, redundancy, and whether human actions are required. Ifisolation is successful, the impact includes the direct impact associated with the initiating event and the applicable train or system containW the pipe fai'ure, and limited spatial considerations. Ifisolation fails, indirect impacts are considered, howevw, the probability ofisolation failure e assessed. Detection and isolation capabilities at ANO-2 nre summarized below:
i e - There is detection capability and procedural guidance for the operators given moderate
- energy line events in the auxiliary building where the greatest potential for impacts can occur.
l l
The auxiliary building sump alarm, ECCS pump room flood alarm, EFW pump room flood alarm, and EDG room flood alarm (References 11 and 20) provide indication of flooding. -
Each SW supply header has a low pressure alarm (55 psig) which can be indicative of a pipe break (Reference 8, page 44). Also, SW supply to the fuel pool exchanger (2E27) has a low /high flow alarm (1300 gpm and 6700 gpm). There are also low /high flow alarms (4800 and 6500 gpm) to SDC exchangers (2E35A and B) and low flow (2400 gpm) to containment cooling coils. Low flow can be indicative of flow diversion due to pipe break in a SW supply header.
. - Loss of flow to local cooling loads (flow indication) will lead to high temperature alarms O
. and/or equipment failures (Reference 9, pages 18 and 19).
Loss of service water procedure 2203.022 (Reference 18) provides direction to the operators. Both service water header low pressure and ACW low pressure alarms are entry l
l' ano_swl. doc 3/26/98 J
1 l
)
l Page 45 Calculation No. NSD-023 l
conditions to this procedure. Step 2 of the procedure checks indications of SW mpture (e.g.,
sump levels or alarms, room level annunciators in alarm, rupture reported). Step 3 separates
)
the two SW headers by isolating FPC and one header supply to CCW. Steps 4 and 5 have operators compare header pressures and walk down ACW ifit is aligned to the header with the lowest pressure. Step 6 verifies SW or ACW rupture is isolated and provides contingency q
actions if the break car uot be isolated.
An assessment of operator response before significant impacts occur is included in determining j
the available mitigating trains in the analysis (Appendix A documents this for each major mn of piping within the system). Generally, failure to isolate is credited as a backup train in the analysis.
When pipe failure does not cause an initiating event (e.g., SW supply is normally isolated, in standby, or the line is small enough to not cause an initiating event, s4 inch), the independent accident demand initiator is evaluated:
For the emergency diesels, loss of offsite power (LOSP, T3) is the appropriate challenge.
For ECCS cooling loads, a small LOCA (S) is chosen, however, when assuming pipe failures
=
in the service water system, non safety service water loads are assumed unavailable or isolated (e.g., feedwater and main condenser are not available).
As described in Section 2, the combination of all impacts is assessed. If an initiatmg event occurs, r
Tables 2-1 and 2-3 are utilized to determine the consequence category, otherwise, Table 2-2 is used.
Piping equal to or less than 4 inch in diameter was reviewed to ensure the analysis of greater. nan 4 inch piping bounds. This smaller piping is judged to be bounded for the following rea.=ms:
Flow is not sufficient to cause a loss of a service water header due to flow diversion (Reference 20).
Piping that is challenged frequently during normal power operation (e.g., switchgear room cooling) is likely to fait during operation with exposure time for an accident determined by a "Long AOT" in Table 2-2. As shown in Table 2-2, only 1 to 2 backup trains are needed to provide a Low consequence depending on the applicable accident challenge.
Piping is small enough such that room drains and/or the ability to propagate under doors to floor drains ensures that flooding impacts are not likely (e.g., no significant spatial impacts identified).
Detection is similar to large pipes, but the time available for isolation is longer.
Table 4-4 sumrr.arizes the results of the review of piping s 4 inches in diameter.
O 4.5 Containment & Combinations V
l ano_swl. doc 3/26/98
Page 46 Calculation No. NSD-023 s-As described in Section 2, containment perfonnance is considered in determining the final consequence category. A containment barrier is required or the consequence evaluation must show margin. For the service water system, only the supply and return lines to containment coolers inside containment have the potential to impact containment isolation. For all postulated pipe failures, there is always a containment barrier. The piping is a closed system inside l
containment and there is an isolation valve outside containment in each supply and retum line.
l Therefore, containment isolation has no impact on the service water consequence analysis
^
results.
l O
i l
l
\\
j
\\ --
l i
i ano_,swl. doc 3/26/98
l i
Page 47 Calculation No. NSD-023 Table 4-1 Type of Pipe Versus Applicable Plant Configurations l
Type of System /
Applicable Configuration Comments l
Piping Normal Test Demand
- 1. Operating or Standby X
Normal - usually an initiating event (IE).
' directly connected to Test - condition does not apply.
operating system (sces Demand - applies, but IE envelopes unless operating pressure) significant loads' are identified.
- 2. Standby and periodic X
X X
Normal - applies, but leakage in a standby pipe testing without operating loads is likely to be small with 2
detection & isolation reliability high,
Test - applies, but detection and isolation reliability high as with " Normal" and piping challenge reduces demand exposure time.
Demand - applies, but periodic testing reduces likelihood of pipe failure unless significant loads' identified.
- 3. Standby and no X
X Normal-same as above periodic testing Test - does not apply.
Demand - applies
- 4. Standby and no X
X Nonnal-same as above accident demand Test - piping is challenged by periodic testing during normal operation.
Demand - does not apply.
- l. Water hammer has occurred in the service water system, but modifications have been made to the system to prevent against such events (Reference 8, pages 15 and 16).
- 2. Auxiliary building and equipment room sump level alarms are available in the control room to provide detection capability (Reference 11).
O l
1 l
ano_swl. doc 3/26/98
Page 48 Calculation No. NSD-023 b
G Table 4-2 Pipe Location & Break Propagation Imtion Description Propagation Path Containment Containment Building None intake Intake Structure Floor grating back to intake bay.
2073-DD General Access (El 354)
Other non safety related rooms at El 354, grating at west end of corridor down to 2040 (tank room) provides easy propagation.
Also, east stai:way, elevator, and floor drains to 2040 and El 317.
2040-JJ General Access (El 335)
Other non safety related rooms at El 335, through east stairwell and floor drains to El 317 (2011 & 2006).
2024-JJ Turbine EFW (El 335)
Watertight room, otherwise to 2040.
2025-JJ Motor EFW (El 335)
Watertight room, otherwise to 2040.
2081-HH North Piping Penetration (El 335 & 354) 2040 2084-DD Upper South Piping Penetration (El 360) 2073 2055-JJ Lower South Piping Penetration (El 335) 2040 Outside Yard and pipeway outside Bldgs No propagation to Auxiliary Bldg and safety equipment.
ATB,TB Auxiliary Turbine Bldg and Main No propagation to Auxiliary Bldg and safety Turbine Bldg.
equipment.
2011-LL Tendon Gallery Access (El317) 2006 first and then 2010 at >lI ft, then
,i 2014 & 2007 at >l2 ft (ventilation opemngs ifopen).
2006-LL General Access Area (El 31")
2011 first and then 2010 at >l1 ft, then 2014 & 2001 at >l2 ft (ventilation openings ifopen).
2014-LL ECCS "A"(El 317) 2006 and 2011 at >l2 feet of water and ventilation openings not isolated.
2007-LL ECCS "B"(El 317) 2006 and 2011 at >l2 feet of water and ventilation opemngs not isolated.
2010-LL HPSI"C"(El 317) 2006 and 2011 at >l1 feet of water and ventilation openings not isolated.
2093-P EDG "A (El 369)
Through cast stairwell to El 317 (2011 &
2006) based on Reference 2, page 3.6-10.
2094-Q EDG"B"(El 369)
'Ihrough east stairwell to El 317 (2011 &
2006) based on Reference 2, page 3.6-10.
2106 Pump Room (El 372)
Through cast stairwell to El 317 (2011 &
2006) based on Reference 2, page 3.6-10.
2093 MCC 2B63 Room (El 372)
Through east stairwell to El 317 (2011 &
2006) based on Reference 2, page 3.6-10.
2139 Corridor & Area Outside CR(El 386)
Through east stairwell to El 317 (2011 &
2006) based on Reference 2, page 3.6-10.
O ano_swl. doc 3/26/98
i Page 49 Calculation No. NSD-023 n
4
(
)
Table 4-3 Large Pipe (>4 inch) Locations and Consequences Pipe Description Location
- Consequence 2HBC-32-20 pump discharge intake SW-C-01 A SW-C-01B SW-C-01C SW-C-02A SW-C-02B SW-C-03 2HBC-33-20 supply header #1 Yard SW-C-4A j
Turbine Bldg SW-C-5A J
Room 2040 SW-C-6A 2HBC-34-20 supply header #2 Yard SW-C-4B Turbine Bldg SW-C-5B Room 2040 SW-C-6B 2HCC-33-20 supply header #1 Room 2040 SW-C-6A 2HCC-34-20 supply header #2 Room 2040 SW-C-6B 2HCC-33-18 supply header #1 Room 2040 SW-C-6A 2HCC-34-18 supply header #2 Room 2040 SW-C-6B 1
2HBD-33-18 supply header to CCW Room 2040 SW-C-07 TAB SW-C-08 2HBD-33-12 supply to CCW HEs TAB SW-C-08
,,(j 2HBD-35-12 retum from CCW HEs 2HBD-35-18 return header from CCW 2HBD-33-10 CCW bypass 2HBD-23-20 CCW & ACW return header TAB SW-C-09 j
Room 2081 SW-C-10 2JBD-618-12 ACW return Room 2081 SW-C-10 TAB SW-C-Il TAB SW-C-27 2JBD-618-8 & 6 ACW retum TAB SW-C-27 2HBD-23-24 cooling tower makeup Room 2081 SW-C-10 TAB SW-C-Il Yard 2HBC-50-16 CCW return to retum header #1 Room 2081 SW-C-12A 2PBC-50-18 return header #1 Room 2040 2HBC-51-16 CCW retum to retum header #2 Room 2081 SW-C-12B 2HBC-51-18 retum header #2 Room 2040 2HBD-26-18 common retum Room 2040 SW-C-13 2HBD-26-24 2HBD-26-30 2HBC-85-6 header #1 supply to EFW 2P7B suction Room 2040 SW-C-06A MOV 2CV-0716-1 Room 2025 SW-C-30A 2HBC-86-6 header #2 supply to EFW 2P7A suction Room 2040 SW-C-06B
,,_3j MOV 2CV-0711-2 Room 2024 SW-C-30B ano_swl. doe 3/26/98
Page 50 Calculation No. NSD-023 Table 4-3 Large Pipe (>4 inch) Locations and Conscauences Pipe Description Location Consequence 2HBC-35-16 supply to ECCS/SDC from header #1 Room 2040 SW-C-06A Room 2006 SW-C-14A l
Room 2014 2HBC-35-14 supply to ECCS/SDC from header #1 Room 2014 SW-C-14A l
2HBC-43-16 supply to ECCS/SDC from header #2 Room 2040 SW-C-06B Room 2006 SW-C-14B 2HBC-43-14 supply to ECCS/SDC from header #2 Room 2006 SW-C-14B Room 2007 2HCC-294-14 return from SDC HE 2E35A Room 2014 SW-C-ISA l
2HBC-59-14 2HBC-59-16 return from SDC HE 2E35A Room 2014 SW-C-ISA Room 2006 Room 2040 SW-C-12A 2HCC-295-14 retum from SDC HE 2E35B Room 2007 SW-C-ISB 2HBC-60-14 2HBC-60-16 retum from SDC FE 2E35B Room 2007 SW-C-ISB Room 2040 SW-C-12B 21BC-68-12 header #1 supply to contamment coolers Room 2040 SW-C-06A Room 2055 SW-C-16A p
Room 2084 SW-C-17 2HBB-2-12 header #1 supply to containment Room 2084 SW-C-18A j
2HBC-103 header #1 to containment coolers Contamment SW-C-19A 2HBC-105 containment coolers retum to header #1 2HBB-4-12 containment cooler retum to header #1 Room 2084 SW-C-20A 2HBC-77-12 containment cooler return to header #1 Room 2084 Room 2055 Room 2040 SW-C-12A i
2HBC-69-12 header #2 supply to contamment coolers Room 2040 SW-C-06B Room 2081 SW-C-16B 2HBB-3-12 header #2 supply to containment Room 2081 SW-C-18B 2HBC-104 header #2 to containment coolers Containment SW-C-19B 2HBC-106 containment coolers retum to header #2 2HBB-5-12 containment cooler retum to header #2 Room 2081 SW-C-20B 2HBC-78-12 containment cooler return to header #2 Room 2081 Room 2040 SW-C-12B 2HBC-63-8 header #1 supply to EDG & CR cooler Room 2040 SW-C-06A Room 2073 SW-C-21 A Room 2093 SW-C-22A 2HBC-75-8 EDG A return to header #1 Room 2093 SW-C-22A Room 2073 SW-C-23A SW-C-24A Room 2040 SW-C-12A 2HBC 64-8 header #2 supply to EDG & CR cooler Room 2040 SW-C-06B ano_swl. doc 3/26/98
Page 51 Calculation No. NSD-023 Table 4-3 Large Pipe (>4 inch) Locations and Consequences Pipe Description Location Consequence Room 2073 SW-C-21B Room 2094 SW-C-22B 2HBC-76-8 EDG A return to header #2 Room 2094 SW-C-22B Room 2073 SW-C-23B SW-C-24B Room 2040 SW-C-12B 2HBC-87-12 header #1 supply to fuel pool HE (2E-27)
Room 2040 SW-C-06A Room 2073 SW-C-25A header #2 supply to fuel pool HE Room 2040 SW-C-06B Room 2073 SW-C-25B common header supply to fuel pool HE Room 2073 SW-C-26 2HBC-81-12 common retum from fuel pool HE (2E-27)
Room 2073 SW-C-26 fuel pool return to header #1 Room 2073 SW-C-26 Room 2040 SW-C-12A fuel pool return to header #2 Room 2073 SW-C-26 Room 2040 SW-C-12B j
2HBC-88-42 SWS suction from emergency pond Yard SW-C-31 2HBC-83-30 SWS return to ECP 2081 SW-C-12A TB, Yard SW-C-32 l
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Page 54 Calculation No. NSD-023 O 5.0 Results This section summarizes the results of the Service Water (SW) system consequence evaluation described in the previous sections and in attached Appendix A. The function of the service water system is to provide cooling water from Lake Dardanelle or the Emergency Cooling Pond (ECP) to cool safety related and non-safety related equipment and provide an emergency supply of water to the Emergency Feedwater (EFW) system and Fuel Pool (FP) system.
Figures 5-1 through 5-6 provide a simplified diagram of service water (SW) major piping, denoting consequence category and plant location. Only key components are shown in these simpli6ed diagrams. There are other components and piping, including manual valves and check valves that are not shown. Table 5-1 summarizes the consequence analysis results in Appendix A.
The following further summarizes these results:
Loss of header #2 in Room 2040 (Consequence SW-C-06B) results in a HIGH consequence e
because large flow rates from the break are assumed to fail MCC 2B52 which fails ECCS A (1 train of once through cooling); the other train of once through cooling fails due to loss of header #2. Conditional core damage probability depends on one train of EFW and not having a LOCA condition (e.g., RCP seal LOCA or stuck opes pressurizer safety).
O
r*e r iiure te i ei te eres siiitv whic* icaa te ie eraii sw i ;ud ed te se a nica consequence (SW-C-07,10,12A,12B, and 13). When the pipe segment is outside the auxiliary building (SW-C-08, 09, and 11), a MEDIUM consequence is based on crediting additional time for operator recoveries.
Most other consequences fall into the MEDIUM category because of the importance of service water dependencies and potential propagation impacts; exceptions are described below.
A LOW consequence was assessed for containment cooler piping located inside containment because the frequency of challenge, testing, and resulting impacts lead to a low CCDP.
Control room emergency condenser piping is the largest (4 inches) of small piping not explicitly eveluated in Appendix A. This piping isjudged small enough to not cause an initiating event (Reference 20), the frequency of challenge is infrequent (LOSP challenge of EDG also supplied by this line isjudged most important) the plant would be shut down after a short AOT, and at
- least a backup train (another diesel and offsite power recovery) results in low to medium consequence.
Also, other small piping (less than 4 inch diameter) was reviewed and judged to be enveloped by the Appendix A analysis and the above evaluation of CR emergency condenser 4 inch piping.
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Page 57 Calculation No. NSD-023 Figure 5-3 Service Water - SDC and ECCS Cooling ECCS A Cooling From Header #1 SW C-14A SW.C-15A 2006,2014 2006,2014 I,
2CV-1400-1 2CV-1453-1 81 Figure Figure SDC HE 5-1 2E-35A 4
52 i
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ECCS Room and Pump J
Coolers ECCS B Cooling From Header #2 SW-C-14B SW-C-I SB 2006,2007 2006,2007 I
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Figure Figurc SDC IIE 5-2 5-1 2E-35B Y
ECCS Room and Pump Coolers
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ano_swl. doc 3/26/98 1
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i Page 59 Calculation No. NSD-023 Figure 5-5 Service Water - EDG and Control Room EDG A From Header #1 If SW-C-21 A
!! SWC22A
. SWC23A SWC-24A 2073 2093 2073 2073
>$ 2CV-1503-1 R.gm Egurc EDGA 4
51 CR Cooler 2VE-IA EDG B From Header #2
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5-1 CR Cooler 2VE1B Ov ano_swl. doc 3/26/98
Page 60 Calculation No. NSD-023 Figure 5-6 Sr.vice Water - Fuel Pool Heat Exchanger
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Page 65 Calculation No. NSD-023 O
6.0 Conclusions & Recommendations The potential for containment performance, shutdown configurations, and external events to influence the results in Section 5 was included in this evaluation. These assessments did not result in changes to the at-power consequence assessment; conclusions from these assessments are summarized below:
Containment isolation reliability is effected by pipe failure in the service water supply to and o
return from the containment coolers. However, the piping is a closed system inside containment with an isolation valve outside on both the supply and return line. Thus, there is always a barrier and/or isolation valve available; this provides sufficient margin to preclude increasing the consequence ranking.
Events during shutdown are judged to be in the Low to Medium consequence range for o
certain piping. However, this same piping is already a Medium or High consequence for the at-power analysis summarized in Section 5. Thus there is no impact assumed from shutdown events.
External events are judged to be in the Low to Medium consequence range for certain piping.
o However, this same piping is already a Medium or High consequence for the at-power analysis summarized in Section 5. Thus there is no impact assumed from external events.
t Conditional core damage probability (CCDP) for certain initiating events is marginally in the
" Medium" or "High" consequence category (see T7, T8, and T9 in Table 2-1). A more detailai
- analysis ofimpacts (e.g., room cooling) and consideration of timing (e.g., time to failure based on loss of cooling) could improve these results. In this study, T7, T8, and T9 are assumed to be in the "High" and " Medium" consequence range.
Several " Low" and " Medium" consequence analysis results depend on successful operator actions to identify the broken pipe and isolate it before additional impacts occur (procedure 2203.022). It may be appropriate to utilize the training simulator and/or operator interviews to discuss some of these scenarios and confirm that the analysis is not too optimistic and/or to identify procedural improvements.
ano swl. doc 3/26/98
Page 66 Cr'.ulation No. NSD-023 O
7.0 References
- 1. EPRI TR-106706, Work Order 3230, Interim Report, June 1996 " Risk-Informed Inservice Inspection Evaluation Procedure" prepared by Electric Power Research Institute, Yankee Atomic Electric Company, and Sartrex Corporation.
I
- 2. ANO Probabilistic Risk Assessment (PRA), Individual Plant Examination (IPE) Submittal, Report No. 94-R-2005-01, Rev 0
- 3. ANO-2 Piping and Instrument Diagrams M-2210, " Service Water System" Sheet 1, Rev 75 M-2210, " Service Water System" Sheet 2, Rev 74 M-2210, " Service Water System" Sheet 3, Rev 76
- 4. ANO-2 Large Pipe Isometric Drawings:
2HBB-2-1 Sheet 1, Rev 6 "Servie:e Water Supply From 2CV-1511-1 to Containment Cooling Coils 2VCC-2A & 2VCC-2B" 2HBB-3-1 Sheet 1, Rev 7 "Contvinment Cooling Coil Service Water Supply to Containment Penetration 2P-55" 2HBB-4-1 Sheet 1, Rev 7 "S.W. Return Piping From Cont. S.W. Cooling Coils 2VCC-2A &.
B to Valve 2VC-1519-1" 2HBB-5-1 Sheet 1, Rev 6 " Penetration Piping From Cooling Coils 2VCC-2C and 2D" 2HBC-32-1 Sheet 1, Rev 19 " Service Water Pump 2P-4A,2P-4B and 2P-4C Discharge and Crossover Piping" 2HBC-32-2 Sheet 1, Rev 13 " Service Water Supply Header #1" 2HBC-33-1 Sheet 1, Rev 12 " Service Water Supply Header #1" 2HBC-33-1 Sheet 2, Rev 0 " Service Water Supply Header #1" 2HBC-33-3 Sheet 1, Rev 9 " Service Water Supply Header #1" 2HBC-33-80 Sheet 1, Rev 14 " Loop i Service Water Supply Header" 2HBC-34-1, Rev 15 " Loop II Service Water Supply Header" 2HBC-34-2 Sheet 1, Rev 8 " Service Water Supply Header #2" 2HBC-34-3 Sheet 1, Rev 8 " Loop II Service Water Supply Header Unit 2 Intake Structure to Turbine Bldg."
2HBC-34-80 Sheet 1, Rev 13 " Loop II Service Water Supply Header Unit 2 Intake Structure to Turbine Building" l
2HBC-34-80 Sheet 2, Rev 1 " Loop II Service Water Supply Header Unit 2 Intake Structure to Turbine Building" 2HBC-35-1 Sheet 1, Rev 15 " Service Water Supply Header to Shutdown Heat Exchanger 2E-35A" 2HBC-41-1 Sheet 1, Rev 14 " Service Water to Control Room Emergency Condensing Unit 2VE-1A" 2HBC-41-1 Sheet 2, Rev 0 " Service Water to Control Room Emergency Condensing Unit 2VE-1 A" 1
ano_swl. doc 3/26/98
)
i c
Page 67 Calculation No. NSD-023 2HBC-43-1 Sheet 1, Rev 14 " Loop 2 Senice Water Supply to Shutdown Cooling Heat Exchanger 2E-35B" 2HBC-50-1 Sheet 1, Rev 15 " Service Water Retum to Header #1" 2HBC-50-2 Sheet 1, Rev 11 " Service Water Return to Header #2 to 2CV-1541-1 Supply to Emergency Pond" 2HBC-51-1 Sheet 1, Rev 13 "Senice Water Return Loop 2" 2HBC-51-2 Sheet 1, Rev 16 " Service Water Return Header Loop 2" 2HBC-59-1 Sheet 1, Rev 23 " Service Water Return From Shutdown Cooling Heat Exchanger 2E-35A to Header #2" 2HBC-59-1 Sheet 2, Rev 8 " Service Water Return From Shutdown Cooling Heat Exchanger 2E-35A to Header #2" 2HBC-60-1 Sheet 1, Rev 17 " Service Water Return From Shutdown Cooling Heat Exchanger l
. 2E-35B to Header #2" 2HBC-63-1 Sheet 1, Rev 20 " Service Water to Emergency Diesel Generator 2K-4A Jacket l
Cooler Heat Exchanger 2E-64A" i
2HBC-63-1 Sheet 2, Rev N " Service Water to Emergency Diesel Generator 2K-4A Jacket l
Cooler Heat Exchanger 2E-64 A" 2HBC-64-1 Sheet 1, Rev 17 " Service Water From Loop II Senice Water Header to Emergency Diesel Jacket Coolef' 2HBC-64-1 Sheet 2, Rev 3 " Service Water From Loop II Senice Water Header to i
Emergency Diesel Jacket Coolef' 2HBC-64-2 Sheet 1, Rev 13 " Service Water to Emergency Diesel Jacket Cooler 2E-64B" 2HBC-68-1 Sheet 1, Rev 10 " Service Water Piping From Loop I Header to Penetration Valve 2CV-1511-1" 2HBC-69-1 Sheet 1, Rev 14 " Service Water Piping to Containment Cooling Coil 2VCC-2D" 2HBC-75-1 Sheet 1, Rev 21 " Service Water From Emergency Diesel Generator 2K-4A Engine Jacket to Reservoir Discharge" 2HBC-75-1 Sheet 2, Rev N "Senice Water From Emergency Diesel Generator 2K-4A Engine Jacket to Reservoir Discharge" 2HBC-76-1 Sheet 1, Rev 18 " Service Water Return From Emergency Diesel Generator Jacket Cooler" 2HBC-76-2 Sheet 1, Rev 20 " Service Water Return From Emergency Diesel Generator Jacket Cooler 2E-20B" 2HBC-77-1 Sheet 1, Rev 15 " Service Water Return From Penetration Line 2HBB-4 to Return Headef' 2HBC-78-1 Sheet 1, Rev 15 "Senice Water Return From Containment Penetration 2P-63 to Header #2"
)
2HBC-81-1 Sheet 1, Rev 10 " Service Water Return From Fuel Pool Heat Exchanger 2E-27" 2HBC-81-1 Sheet 2, Rev 2 " Service Water Return From Fuel Pool Heat Exchanger 2E-27" 2HBC-81-2 Sheet 1, Rev 7 " Service Water Return Piping From Heat Exchanger 2E-27 to Service Water Headef' 2HBC-83-1 Sheet 1, Rev 9 " Service Water Return to Emergency Cooling Pond" 2HBC-83-2 Sheet 1, Rev 7 " Service Water Return to Emergency Cooling Pond" h
2HBC-83-2 Sheet 2, Rev 0 " Service Water Return to Emergency Cooling Pond" 2HBC-83-80 Sheet 1, Rev 16 " Emergency Cooling Water Discharge to Emergency Pond" ano_swl. doc 3/26/98
l l
Page 68 Calculation No. NSD-023
(
2HBC-83-81 Sheet 1, Rev 9 " Emergency Cooling Water Discharge to Emergency Pond" 2HBC-87-1 Sheet 1, Rev 9 " Service Water Header #2 Supply to Spent Fuel Pool Heat Exchanger" 2HBC-87-2 Sheet 1, Rev 8 " Service Water to Fuel Pool Heat Exchanger" 2HBC-88-80 Sheet 1, Rev 5 " Emergency Cooling Pond Piping to Senice Water Pump Bays" 2HBC-88-81 Sheet 1, Rev 5 " Emergency Pond Discharge to Service Water Pump Suction" 2HBC-88-82 Sheet 1, Rev 10 " Emergency Pond Discharge to Service Water Pump Suction" 2HBC-98-1 Sheet 1, Rev 15 " Service Water From Control Room Emergency Chiller 2VE-1B to 2K-4B Heat Exchanger" 2HBC-103 1 Sheet 1, Rev 9 " Service Water Supply to 2VCC-2A & 2B" 2HBC-103-2 Sheet 1, Rev 8 " Service Water Supply to 2VCC-2A" 2HBC-103-3 Sheet 1, Rev 8 " Service Water Supply to 2VCC-2B" 2HBC-104-1 Sheet 1, Rev 12 " Service Water Supply to 2VCC-2C & 2D" 2HBC-104-2 Sheet 1, Rev 10 " Service Water Supply to 2VCC-2C & 2D" 2HBC-104-3 Sheet 1, Rev 9 " Service Water Supply to 2VCC-2D" 2HBC-105-1 Sheet 1, Rev 8 " Service Water Return From 2VCC-2A & 2B" 2HBC-105-2 Sheet 1, Rev 11 " Service Water Return From 2VCC-2A & 2B" 2HBC-105-3 Sheet 1, Rev 8 " Service Water Return From 2VCC-2A & 2B" 2HBC-106-1 Sheet 1, Rev 8 " Service Water Return" 2HBC-106-2 Sheet 1, Rev 8 " Service Water Return From 2VCC-2C" 2HBC-106-3 Sheet 1, Rev 9 " Service Water Return From 2VCC-2D" p
2HBD-23-1 Sheet 1, Rev 13 " Service Water From Auxiliary Cooling System to Cooling U
Tower" 2HBD-23-2, Rev 4 " Service Water" 2HBD-23-80, Rev 9 " Service Water Return Piping (Headers)"
2HBD-23-81, Rev 5 "24" Service Water Return Piping" 2HBD-26-1 Sheet 1, Rev 12 "Senice Water Return to Reservoir Via Unit 1 Outfall" 2HBD-33-1 Sheet 1, Rev 12 " Component Cooling Water Heat Exchangers 2E-28A, B & C Senice Water Supply" 2HBD-35-1, Rev 9 " Isometric Turbine Aux. Bldg. Service Water Branches" 2HCC-296-1 Sheet 1, Rev 2 "Senice Water Supply to Control Room Emergency Condenser 2VE-1 A)"
2HCC-298-1 Sheet 1, Rev 1 " Service Water Supply to Control Room Emergency Chiller 2VE-1B)"
2HBC-83-1 Sheet 1, Rev 9 " Service Water Return to Emergency Ooling Pond" 2HBC-83-2 Sheet 1, Rev 7 " Service Water Return to Emergency voling Pond" 2HBC-83-2 Sheet 2, Rev 0 " Service Water Return to Emergency Cooling Pond" 2HBC-83-80 Sheet 1, Rev 16 " Emergency Cooling Water Discharge to Emergency Pond" 2HBC-83-81 Sheet 1, Rev 9 " Emergency Cooling Water Discharge to Emergency Pond" 2HBC-88-80 Sheet 1, Rev 5 " Emergency Cooling Pond Piping to Service Water Pump Bays" 2HBC-88-81 Sheet 1, Rev 5 " Emergency Cooling Pond Piping to Service Water Pump Bays" 2HBC-88-82 Sheet 1, Rev 10 " Emergency Pond Discharge to Senice Water Pump Suction" 2JBD-618-1 Sheet 1, Rev 7 " Turbine Aux Building Regenerative Waste" V l 2JBD-618-2 Sheet 1, Rev 5 " Turbine Aux Building Regenerative Waste" 2JBD-618-3 Sheet 1, Rev 6 " Turbine Aux Building Regenerative Waste" ano_swl. doc 3/26/98
]
Page 69 Calculation No. NSD-023 2JBD-618-4 Sheet 1, Rev 4 " Turbine Aux Building Regenerative Waste" i
j 2JBD-618-5 Sheet 1, Rev 4 " Turbine Aux Building Regenerative Waste"
- 5. ANO-2 Plant Design Drawings:
M-2045, Rev 43 " AREA 24 Containment Auxiliary BLDG Plan EL 335 to 354" M-2038, Rev 37 " AREA 23 Containment Auxiliary BLDG Plan EL 354" M-2033, Rev 46 " AREA 23 Contaimaent Auxiliary BLDG Plan EL 354 to 368" M-2044, Rev 31 " AREA 24 Containment AUX Building Plan EL 354 to 372" l
M-2070, Rev 12 " Condensate Storage tank & Reactor Makeup Tank Plan & Sections" l
M-2056, Rev 24 " AREA 25 Containment Building Plan EL 357 to 376-6" 1
M-2055, Rev 27 " AREA 25 Containment Building Plan EL 376-6 to 405-6" M-2054, Rev 21 " AREA 25 Containment Building Plan EL 405-6 to 426-6" M-2040 SHT 4, Rev 13 " AREA 23 Turbine Auxiliary BLDG Section U23-U23" M-2040 SHT 3, Rev 13 " AREA 23 Turbine Auxiliary Building Section G23-G23" M-2040 SHT 5, Rev 13 " AREA 23 Turbine Auxiliary BLDG Miscellaneous Sections" M-2040 SHT 6, Rev 12 " AREA 23 Turbine Auxiliary BLDG Section E23-E23" l
M-2845, Rev 12 "Small Piping AREA 24 Containment Auxiliary BLDG Plan El 335 to 354" M-2838, Rev 11 "Small Piping AREA 23 Turbine Auxiliary BLDG Plan El 354"
- 6. ANO Fire Hazards Analysis, Rev 3, Controlled Set #16
- 8. ANO Unit 2 System Training Manuals:
1 Service Water & Auxiliary Cooling Water Systems, STM 2-42, Rev 4 I
j
- 9. Design Configuration Documentation Project:
l ANO-2 Service Water System, ULD-2-SYS-10, Revision 0
- 10. ANO-2 Internal Flooding Study (ANO-2 Calculation No. 89-E-0048-35, Rev 0)
- 11. ANO-2 Control Room Indications and Annunciators Procedure 2203.012W, page 2 of 14, Rev 11, Annunciator 2K15, A-1, AUX BLDG SUMP LEVEL HIGH.
Procedure 2203.012L, page 77 and 78 of100, Rev 27, Annunciator 2K12, H-8, ESF l
ROOM (S) LEVEL HI.
Procedure 2203.012L, page 79 of 100, Rev 27, Annunciator 2K12, J-8, TURBINE BLDG SUMP STA 6 LEVEL HI.
Procedure 2203.012L, page 90 of 100, Rev 27, Annunciator 2K12, J-9, TURBINE BLDG SUMP STA 2 LEVEL HI.
Procedure 2203.012L, page 89 of 100, Rev 27, Annunciator 2K12, H-9, EFWP ROOM (S)
LEVEL HI.
Procedure 2203.012L, page 90 of 100, Rev 27, Annunciator 2K12, J-9, TURBINE BLDG j
t l
ano_swl. doc 3/26/98
Page 70 Calculation No. NSD-023 Procedure 2203.012J, page 67 of 76, Rev 26, Annunciator 2K10, B-7, CNTMT SUMP LEVEL HI.
Procedure 2203.012G, pages 54 of 59, Rev 20, Annunciator 2K07, E-9,2P7B SUCT PRESS HI/LO.
l
, Procedure 2203.012C, pages 83 of 137, Rev 19, Annunciator 2K03, C-9, PUMP SUCT PRESS LO.
i
- 12. ANO-2 Technical Specifications 3/4.7.1.3 Service Water System 3/4.6.2.3 Containment Cooling System (page 3/4 6-14, Amendment 29 and page 3/4 6-15, i
1 Amendment 149) l i
l
- 13. North Atlantic Energy Services Corp. " Individual Plant Examination External Events" Report for Seabrook Station, Response to Generic Letter 88-20, Supplement 4, September 1992.
)
- 14. EPRI NP-6395-D, April 1989, "Probabilistic Seismic Hazard Evaluations at Nuclear Plant 1
Sites in the Central and Eastern United States: Resolution of the Charleston Earthquake Issue" Prepared by Risk Engineering, Inc.,- Yankee Atomic Electric Company, and l
Woodward-Clyde Consultants.
- 15. NUREG-1488, " Revised Livermore Seismic Hazard Estimates for 69 Nuclear Power Plant l
Sites East of the Rocky Mountains" Final Report, April 1994.
- 16. Summary Report ofIndividual Plant Examination of External Events (IPEEE) for Severe Accident Vulnerabilities for Arkansas Nuclear One, Unit 2, May 1996.
- 17. ANO Procedure 2104.029 " Service Water System Operations" Rev 46
- 18. ANO Procedure 2203.022 " Loss of Service Water" Rev 7
- 19. ANO Procedure 2311.002 " Service Water System Flow Test" Rev 10
.20. ANO-2 Service Water System Walkdown Notes, ANO-2 Letter No.ANO-98-2-00052, Rhck Fougerousse to Pat O'Regan dated March,1998.
l I
O l
l ano_swl. doc 3/26/98
Page 71 Calculation No. NSD-023 O
Appendix A - Consequence Analysis Results (SW System)
O O
ano_swl. doc 3/26/98 I
Page 72 Calculation No. NSD-023 Consequence ID: SW-C-Ol A l
Consequence
Description:
2P-4A Discharge Inside Intake Structure and to 2CV-1418-1 (2HBC-32-20)
During Operation Break Size: Large Isolability of Break: Yes l
ISO Comments: Stop pump 2P-4A or 4B (depends on which one is operating) and if aligned to ACW l
system, close either 2CV-1418-1 or 2CV-1419-1. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection.
Spatial Effects: None Effected Location: Intake Spatial Effects Comments: There are openings in the floor to prevent flooding and retum water to the service water bay (FS AR Section 9.2.1).
Initiating Event: I Initiating Event ID: T8 Initiating Event Recovery: Loss of 2P-4A and service water header #1 unavailable and assumed not recovered in this analysis.
Loss of System: SD System IPE ID: NA System Recovery: CCW is partially isolated per Procedure 2203.022. Also,if ACW is aligned, it would be isolated and could be recovered from the other unaffected header. Not all CCW and ACW loads can be supplied unless both remaming pumps are available.
Loss of Train: T Train ID: SW Header #1
[
Train Recovery: See Initiating Event Recovery.
Consequence Comments: Consequence is " Medium" based on Table 2-1.
Consequence Category: MEDIUM l
l 1
l i
l /3 (V
l l
l ano_,swl. doc 3/26/98 l
Page 73
' Calculation No. NSD-023 Consequence ID: SW-C-OlB Consequence
Description:
2P-4C Discharge Inside Intake Structure and to 2CV-1422-2 (2HBC-32-20)
During Operation Br< ak Size: Large Isolability of Break: Yes ISO Comments: Stop pump 2P-4C or 4B (depends on which one is operating) and if aligned to ACW system, close either 2CV-1422-2 or 2CV-1421-2. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection.
Spatial Effects: None Effected Location: Intake Spatial Effects Comments: There are arrninge in the floor to prevent flooding and return water to the service water bay (FSAR Section 9.2.1).
Initiating Event: I Initiating Event ID: T9 Initiating Event Recovery: Loss of 2P-4C and service water header #2 unavailable and assumed not recovered in this analysis.
Loss of System: SD System IPE ID: NA System Recovery: CCW is partially isolated per Procedure 2203.022. Also,if ACW is aligned, it would j
be isolated and could be recovered from the other urdected header. Not all CCW and ACW loads can be supplied unless both remauung pu.nps are available.
Loss of Train: T Train ID: SW Header #2 Train Recovery: See Initiating Event Recovery.
Consequence Comments: Consequence is " Medium" based on Table 2-1.
Consequence Category: MEDIUM i
O ano_,swl. doc 3/26/98
Page 74 Calculation No. NSD-023
' Consequence ID: SW-C-01C Consequence
Description:
2P-4B Discharge Inside Intake Structure and to 2CV-1419-1, 2CV-1421-2, &
2CV-1425-1 (2HBC-32-20) During Operatum BreakSize: Large Isolability of Break: Yes ISO Comments: Stop pump 2P-4B (if runmng) and isolate the maw service water header as well as ACW. Close either 2CV-1418-1 or 2CV-1419-1 if aligned to header 1. Close either 2CV-1422-2 or 2CV-1421-2 if aligned to header 2. Closing 2CV-1425-1 or 2CV1427-2 will isolate ACW. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection.
SpatialEffects: None Effected Location: Intake Spatial Effects Comments: There are openings in the floor to prevent floodmg and return water to the service water bay (FSAR Section 9.2.1).
J Initiating Event: I Initiating Event ID: T8 or T9 Initiating Event Recovery: Loss of 2P-4B, a service water header (it is assumed that 2P-4B is operatmg) and ACW. If the backup pump is available to supply the isolated header, the service water header can be recovered.
Loss of System: S System IPE ID: NA System Recovery: CCW is partially isolated per Procedure 2203.022. ACW is unavailable and assumed not recoverable.
Loss of Train: T Train ID: SW Header #1 or #2 l
Train Recovery: See Initiating Event Recovery.
Consequence Comments: Consequence is " Medium" based on Table 2-1.
Consequence Category: MEDIUM i
O ano_swl. doc 3/26/98
Page 75 Calculation No. NSD-023
' Consequence 1D: SW-C-02A Consequence
Description:
2P-4A & 2P-4B Discharge Crosstie Between 2CV-1418-1 and 2CV-1419-1 Inside Intake Structure (2HBC-32-20) During Operation Break Size: Large Isolability of Break: Yes
. ISO Comments: Closure of 2CV-1418-1 and 2CV-1419-1 isolates the break. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection.
Spatial Effects: None Effected Location: Intake Spatial Effects Comments: There are openings in the floor to prevent floodmg and return water to the service water bay (FSAR Section 9.2.1).
1 Initiating Event: I Initiating Event ID: T8 Initiating Event Recovery: If 2P-4A is initially runmng or can be started, isolation restores service water beader #1. If 2P-4B is initially running or can be started, isolation restores ACW.
Loss of System: S SystemIPEID: ACW System Recovery: CCW is partially isolated per Procedure 2203.022. ACW can be recovered (see Initiating Event Recovery).
Loss of Train: T Train ID: SW Header #1 Train Recovery: See Initiating Event Recovery.
Consequence Comments: Consequence is " Medium" based on Table 2-1.
Consequence Category: MEDIUM O
ano_swl. doc 3/26/98
Page 76 Calculation No. NSD-023 Consequence ID: SW-C-02B Consequence
Description:
2P-4C & 2P-4B Discharge Crosstie Between 2CV-1422-2 and 2CV-1421-2 Inside Intake Structure (2HBC-32-20) During Operation Break Sise: Large Isolability of Break: Yes ISO Comments: Closure of 2CV-1422-2 and 2CV-1421-2 isolates the break. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection.
Spatial EKects: None EKected Location: Intake I
Spatial EKects Coni:nents: There are openings in the floor to prevent flooding and return water to the service water bay (FSAR Section 9.2.1).
Initiating Event: I Initiating Event ID: T9 Initiating Event Recovery: If 2P-4C is initially runmng or can be started, isolation restores service water header #2. If 2P-4B is initially running or can be started, isolation restores ACW.
Loss of System: S SystemIPEID: ACW System Recovery: CCW is partially isolated per Procedure 2203.022. Also, ACW can be recovered (see Initiating Event Recovery).
Loss of Train: T Train ID: SW Header #2 Train Recovery: See Initiating Event Recovery.
Consequence Comments: Consequence is " Medium" based on Table 2-1.
Consequence Category: MEDIUM i
i 1
ano_swl. doc 3/26/98.
Page 77 Calculation No. NSD-023 Consequence ID: SW-C-03 Consequence
Description:
Crosstic Supply to ACW Inside Intake Structure Between 2CV-1425-1 and 2CV-1427-2 (2HBC-32-20) During Operation Break Size: Large Isolability of Break: Yes ISO Comments: Closing 2CV-1425-1 isolates the break. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection.
SpatialEKeets: None Effected Location: Intake.
Spatial Effects Commentsr. There are openmgs in the floor to prevent floodmg and return water to the service we.er bay (FSAR Section 9.2.1).
Initiating Event: I Initiating Event ID: T8 or T9 Initiating Event Recovery: S'.ccessful isolation results in loss of ACW (Turbine trip, TI). Failure to i.olate is equivalent to loss of service water pump and header due to flow
.fiversion (T8 or T9) and ACW due to flow diversion.
Loss of System: S SystemIPEID: ACW System Recovery: CCW is partially isolated per Procedure 2203.022. ACW is unavailable and assumed not recoverable.
Loss of Train: T Train ID: SW Header #1 or #2 Train Recovery: Loss of service water header if unisolated. See Initiating Event Rwvery.
(
Consequence Comments: Consequence is " Medium" based on Table 2-1.
Consequence Category: MEDIUM j
ano_swl. doc 3/26/98 i
Page 78 Calculation No. NSD-023 e
Consequence ID: SW-C-04A L
Consequence
Description:
Header #1 in Yard (2HBC-33-20) During Operation Break Size: Large Isolability of Break: Yes ISO Comments: Stop pump 2P-4A or 4B (depends on which one is operating) and if aligned to ACW system, close either 2CV-1418-1 or 2CV-1419-1. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection.
SpatialEffects: None Effected Location: Yard Spatial Effects Comments: This pipias is underground in the Yard; no impacts identified.
Initiating Event: I Initiating Event ID: T8 Initiating Event Recovery: Loss of 2P-4A and service water header #1 unavailable and assumed not recovered in this analysis.
Loss of System: S SystemIPEID: ACW System Recovery: CCW is partially isolated per Procedure 2203.022. Also, if ACW is aligned, it would be isolated and could be recovered from the other unaffected header and/or pumps.
Loss of Train: T Train ID: SW Header #1 Train Recover 3 : See Initiating Event Recovery.
Consequence Ct wnents: Consequence is " Medium" based on Table 2-1.
Consequence Catepry: MEDIUM O
ano,_swl. doc 3/26/98
l Page 79 Calculation No. NSD-023 O ' Consequence ID: SW-C-04B O
Consequence
Description:
Header #2 in Yard (2HBC-34-20) During Operation Break Size: Large Isolability of Break: Yes ISO Comments: Stop pump 2P-4C or 4B (depends on which one is operating) and if aligned to ACW
' system, close either 2CV-1422-2 or 2CV-1421-2. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection.
Spatial Effects: None Effected Location: Yard Spatial Effects Comments: This piping b underground in the Yard; no impacts identified.
Initiating Event: I Initiating Event ID: T9 Initiating Event Recovery: Loss of 2P-4C and service water header #2 unavailable and assumed not recovered in this analysis.
Loss of System: S SystemIPEID: ACW System Recovery: CCW is partially isolated per Procedure 2203.022. Also, if ACW is aligned, it would be isolated and could be recovered from the other unnFmed header and/or pumps.
Loss of Train: T Train ID: SW Header #2 Train Recovery: See Initiating Event Recovery.
Consequence Comments: Consequence is " Medium" based on Table 2-1.
Consequence Categor/: MEDIUM i
l l
i l
l l
l ano_swl. doc 3/26/98
Page 80 Calculation No. NSD-023
- Consequence ID: SW C-05A Consequence
Description:
Header #1 in Turbine Buildmg (2HBC-33-20) During Operation Break Size: Large Isolability of Break: Yes ISO Comments: Stop pump 2P-4A or 4B (depends on which one is operatmg) and if aligned to ACW system, close either 2CV-1418-1 or 2CV-1419-1. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection.
Spatial Effects: local Effected Location: TB Spatial Effects Comments: This piping is in the Turbine Building which is a very large area to collect water before propagation out of the building. It is assumed power conversion system and its support systems could be affected.
Initiating Event: I InitiatingEventID: T8 Initiating Event Recovery: loss of 2P-4A and service water header #1 unavailable and assumed not recovered in this analysis.
Loss of System: S SystemIPEID: ACW System Recovery: CCW is partially initially isolated per Procedure 2203.022. Also, if ACW is aligned, it would be isolated and could be recovered from the other undei header and/or pumps.
Loss of Train: T Train ID: SW Header #1 Train Recovery: See Initiating Event Recovery.
Consequence Comments: Consequence is " Medium" based on Table 2-1.
Consecuence Category: MEDIUM O
ano_swl. doc 3/26/98
Page 81 Calculation No. NSD-023 Consequence ID: SW C-05B Consequence
Description:
Header #2 in Turbine Building (2HBC-34-20) During Operation BreakSize: Large Isolability of Break: Yes ISO Comments: Stop pump 2P-4C or 4B (depends on which one is operating) and if aligned to ACW system, close either 2CV-1422-2 or 2CV-1421-2. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection.
Spatial Effects: Iml Effected Location: TB Spatial Effects Comments: This piping is in the Turbine Building which is a very large area to collect water b-fore propagation out of the building. It is assumed power conversion system and its support systems could be affected.
Initiating Evat: I Initiating Event ID: T9 Initiating Event Recovery: Loss of 2P-4C and service water header #2 unavailable and assumed not recovered in this analysis.
Loss of System: S SystemIPEID: ACW
' System Recovery: CCW is partially isolated per Procedure 2203.022. Also, if ACW is aligned,it would be isolated and could be recovered from the other unaffected header and/or pumps.
Loss of Train: T Train ID: SW Header #2 Train Recovery: See Initiating Event Recovery.
Consequence Comments: Consequence is ' Medium" based on Table 2-1.
Consequence Category: MEDIUM l
l O
ano_swl. doc 3/26/98
- Page 82 Calculation No. NSD-023 Consequence ID. SW-C-06A Consequence
Description:
Header #1 in AB Room 2040 During Operation (2HCC-33-20,2HBC-33-20, 2HBC-33-18 up to 2CV-1530-1,2HBC-35-16 in Room 2040,2HBC-87-12 in Room 2040,2HBC-85-6 in Rooms 2040,2HBC-68-12 in Room 2040,2HBC-63-8 in Room 2040)
Break Size: Large Isolability of Break: Yes ISO Comments: Stop pump 2P-4A or 4B (depends on which one is operatmg) and if ahaned to ACW system, close either 2CV-1418-1 or 2CV-1419-1. Procedure 2203.022 provides direction to isolate based on low hemier pressure providmg detection. Also, auxihary building sump alarms provide detection.
Spatial EKects: Propagation -
Effected Location: Room 2040 Spatial Effects Comments: Propagation is to El 317 (Rooms 2006 & 2011) through floor drains and east stairway. Room 2040 is a very large floor area, but eventually water could accumulate and fail MCC 2B52. De MCC is assumed to fail before isolation if the break is in the main supply or return headers (i.e., very high flow rates).
%e MCC fails Train A ECCS valves includmg CSS Valves 2CV-5612-1 and 2CV-5649-1 (Sump Recirculation A). An unisolated break would evetually fill El 317 and it is assumed that all ECCS equipment is flooded (propagataan into rooms 2007,2010, & 2014).
Initiating Event: 1 Initiating Event ID: T8 Initiating Event Recovery: loss of 2P-4A and service water header #1 unavailable and assumed not recovered in this analysis. It is also assumou u.4 --~1 piping in standby (i.e., no flow) sees sufficient SW pressure to be challenged during normal operation.
Loss of System: S SystemIPEID: ACW f
System Recovery: CCW is partially isolated per Procedure 2203.022. Also, if ACW is ahgned, it would l
be isolated and could be recovd from the other unaffected header and/or pumps.
l Loss of Train: T TrainID: SWHeader#1 Train Recovery: See Initiating Event Recovery.
Consequence Comments: Consequence is " Medium" ba en on Table 2-3 with 2 backup trains (EFW A, possibly PCS, and I train of once through cooling). For the failure to isolate case, there are 2 backup trains (failure to isolate, EFW A, and possibly AFW)
Consequence Category: MEDIUM O
ano_swl. doc 3/26/98
Page 83 Calculation No. NSD-023 Consequence ID: SW-C-06B Consequence
Description:
Header #2 in AB Room 2040 During Operation (2HCC-34-20,2HBC-34-20, 2HBC-34-18 up to 2CV-1531-2,2HBC-43-16 in Room 2040,2HBC-87-12 in Room 2040,2HBC-86-6 in Rooms 2040,2HBC-69-12 in Room 2040,2HBC-64-8 in Room 2040)
Break Size: Large Isolability of Break: Yes ISO Comments: Stop pump 2P-4C or 4B (depends on which one is operating) and if aligned to ACW system, close either 2CV-1422-2 or 2CV-1421-2. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection. Also, auxiliary building sump alarms provide detectiort SpatialEffects: Propagation Effected Location: Room 2040 Spatial Effects Comments: Propagation is to El 317 (Rooms 2006 & 2011) through floor drains and east stairway. Room 2040 is a very large floor area, but eventually water could accumulate and fail MCC 2B52. The MCC is assumed failed before isolation if the break is in the main supply or return headers (i.e., very high flow rates).
The MCC fails Train A ECCS valves including CSS Valves 2CV-5612-1 and 2CV-5649-1 (Sump Recirculation A). An unisolated break would eventually fill El 317 and it is assumed thst all ECCS equipment is flooded (propagation into rooms 2007,2010, & 2014).
Initiating Event: I Initiating Event ID: T9 Initiating Event Recovery: Loss of 2P-4C and service water header #2 unavailable and assumed not recovered in this analysis. It is also assumed that connected piping in standby (i.e., no flow) sees sufIicient SW pressure to be challenged during normal operation.
Loss of System: S SystemIPEID: ACW System Recovery: CCW is partiallyisolated per Procedure 2203.022. Also, if ACW is aligned, it would be isolated and could be recovered from the other unaffected header and/or pumps.
Loss of Train: T Train ID: SW Header #2 Train Recovery: See Initiating Event Recovery.
Consequence Comments: Consequence is "High" based on Tabic 2-3 withless than 2 backup trams (EFW B and possibly AFW). For the failure to isolate case, there are 2 backup trains (failure to isolate, EFW B, and possibly AFW).
Consequence Category: HIGH o
V ano_swl. doc 3/26/98
Page 84 Calculation No. NSD-023 Consequence ID: SWC-07 Consequence
Description:
CCW supply Downstream of 2CV-1530-1 and 2CV-1531-2 In Room 2040 During Operation (HBD-33-18 in Room 2040)
Break Size: Large Isolability of Break: Yes ISO Comments: Isolate 2CV-1530-1 and 2CV-1531-2. This would restore both service water safety related headers. If an MOV fails, the aligned service water pump could be tripped.
Procedure 2203.022 provides direction to isolate based on low header pressure provxhng detection. Also, auxiliary building sump alarms provide detection.
SpatialEffects: Propagation Effected Location: Room 2040 Spatial Effects Comments: Propagation is to El 317 (Rooms 2006 & 2011) through floor drams and east stairway. Room 2040 is a very large floor area, but eventually water could accumulate and fail MCC 2B52. 'Ihe MCC is assumed fail before isolation if the break is in the main supply or return headers (i.e., very high flow rates).
1 The MCC fails Train A ECCS valves including CSS Valves 2CV-5612-1 and 2CV-5649-1 (Sump Recirculation A). An unisolated break would eventually j
fill El 317 and it is assumed that all ECCS equipment is flooded (propagation into rooms 2007,2010, & 2014).
Initiating Event: I Initiating Event ID: T7 i
Initiating Event Recovery: Potential flow diversion of both trams is assumed. Isolation success restores both safety related headers with loss of CCW (RCP cooling and auxiliaries).
O Loss ofSystem: S' SystemIPEID: CCW System Recovery: CCW is lost as well as systems dependent on CCW (loss of power conversion system can be assumed).
)
f Loss of Train: T Train ID: SW Header #1 or #2 Train Recovery: See Initiatmg Event Recovery.
Consequence Comments: Consequence is "High" for the failure to isolate case based on Table 2-3 with I backup train (isolation). Successful isolation is a " Medium" based on Table 2-3 with 2 backup trains (EFW and 1 train of once through cooling).
Consequence Category: HIGH O
i ano_swl. doc 3/26/98 j
Page 85 Calculation No. NSD-023 s
Consegnence ID: SW-C-08 Consequence
Description:
CCW supply Downstream of 2CV-1530-1 and 2CV-1531-2 in Turbine Bldg During Operation (2HBD-33-18, 2HBD-33-12, 2HBD-35-12, 2HBD-35-18, 2HBD-33-10)
Break Size: 1.arge Isolability of Break: Yes ISO Conunents: Isolate 2CV-1530-1 and 2CV-1531-2. 'Ihis would restore both service water safety related headers. If an MOV fails, the aligned service water pump could be tripped. For portions of 2HBD-35 close to the return header (2HBD-23-20), ACW may have to be isolated to prevent floodmg. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection. There are also sump alarms in the turbine building.
SpatialEffects: Propagation Effected Location: TAB Spatial Effects Comments: Turbine auxiliary building propogates into turbine building with pawi=1 impacts on power conversion system and its support systems Initiating Event: 1 Initiating Event ID: T7 Initiating Event Recovery: Potential flow diversion of both trains is =s= mad Isolation success restores both saf-N related headers with loss of CCW (RCP cooling and auxiliaries).
Loss of System: S SystemIPEID: CCW System Recovery: CCW is lost due to isolation as well as systems dependent on this system (loss of power conversion system can be assumed).
Loss of Train: T Train ID: SW Header #1 or #2 Train Recovery: loss of headers due to flow diversion until isolation. Se,- Initiatmg Event Recovery, Consequence Comments: Consequence is " Medium" based on Table 2-3 with 2 backup trains (EFW and once through cooling). For the failure to isolate case, there are 2 backup trams (because break is outside RAB,2 opportunities to fail isolation and/or recover EFW or AFW or once throu8 cooling).
h
' Consequence Category: MEDIUM ano_,swlidoc 3/26/98
Page 86 Calculation No. NSD-023 Consequence ID: SW-C-09 Consequence
Description:
CCW & ACW Retum Header in Turbine Bldg (2HBD-23-20 in TAB)
Creek Size: Large Isolability of Break: Yes ISO Comments: Both CCW (2CV-1530-1 and 2CV-1531-2 closed) and ACW supply MOVs must be isolated to prevent further flooding. Also,2CV-1543-1 and 2CV-1542 (isolate CCW and ACW from main service water return headers) may need to be closed to prevent back flow (depends on system hydraulics). This would restore both service water safety related headers. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection. There are also sump alarms in the turbine building.
Spatial Effects: Propagation Effected Location: TAB Spatial Effects Comments: TurbN auxiliary building propogates into turbine building with potential impaus on power conversion system and its support systems.
Initiatiag Event: I Initiating Event ID: T7 Initiating Event Recovery: Potential flow diversion of both trains is assumed. Isolation success restores both safety related headers with loss of CCW (RCP cooling and auxiliaries).
Loss of System: SM-2 SystemIPEID: CCW, ACW System Recovery: CCW and ACW are lost due to isolation as well as systems dependent on these systems (loss of power conversion system can be assumed).
O Loss of Train: TM-2 Train ID: SW Header #1 and #2 Train Recovery: Loss of both headers due to flow diversion until isolation. See initiating Event Recovery.
Consequence Comments: Consequence is " Medium" based on Table 2-3 with 2 backup trams (EFW and once through cooling). For the failure to isolate case, there are 2 backup trams (because break is outside RAB,2 opportunities to fail isolation and/or recover EFW or AFW or once through cooling).
Consequence Category: MEDIUM ano swl. doc 3/26/98
Page 87 Calculation No. NSD-023 Consequence ID: SW-C-10 Consequence
Description:
CCW & ACW Return Header in Room 2081 Upstream of Header Isolation Valves 2CV-1543-1 and 2CV-1542-2 During Operation (2HBD-23-20, 2HBD-23-24, and 2JBD-618-12 in Room 2081)
BreakSize: Large Isolability of Break: W ISO Comments: Both CCW (2CV-1530-1 and 2CV-1531-2 closed) and ACW rupply MOVs must be isolated to prevent flooding. Also,2CV-1543-1 and 2CV-1542 (isolate CCW and ACW from main service water return headers may need to be closed to prevent back flow (depends on system hydraulics). His would restore both service water safety related headers. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection. There are also sump alarms in the turbine building. Also, auxiliary building sump alarms provide detection.
Spatial Effects: Propagation Effected Location: Room 2081 Spatial Effects Comments: Room 2081 propoagates into Room 2040. Room 2040 propagation is to El 317 (Rooms 2006 & 2011) through floor drams and cast stairway. Room 2040 is a very large floor area, but eventu.Ily water could accumulate and fail MCC 2B52. The MCC is assumed fail before isolation if the break is in the main supply or return headers (e.g., very high flow rates). He MCC fails Train A ECCS valves including CSS Valves 2CV-5612-1 and 2CV-5649-1 (Sump Recirculation A). An unisolated break would eventually fill El 317 and it is assumed that all ECCS equipment is flooded (propagation into rooms 2007,2010, & 2014).
Initiating Event: I Initiating Event ID: T7 Initiating Event Recovery: Potential flow diversion of both trains is assumed. Isolation success restores both safety related headers with loss of CCW (RCP cooling and auxiliaries).
Loss of System: SM-2 SystemIPEID: CCW, ACW System Recovery: CCW and ACW are lost due to isolation as well as systems dependent on these systems (loss of power conversion system can be assumed).
Loss of Train: TM-3 Train ID: SW Header #1 and #2 Train Recovery: Loss of both headers due to flow diversion until isolation. See Initiating Event Recovery.
Consequence Comments: Consequence is "High" for the failure to isolate case based on Table 2-3 with I backup train (isolation). Successful isolation is a " Medium" based on Table 2-3 with 2 backup trams (EFW and I train of once through cooling).
Consequence Category: HIGH ano_swl. doc 3/26/98
Page 88 Calculation No. NSD-023 Consequence ID: SW-C-11 Consequence
Description:
Makeup to Cooling Tower Basin in Turbine Bldg & Yard Dunng Operation and ACW retum in the Turbine building (2HBD-23-24 in TAB & Yard and 2JBD-618-12 in TAB downstream of check valve 2ACW-54)
Break Size: Large Isolability of Break: Yes ISO Comments: Closure of 2CV-1540 isolates a cooling tower maeup break. As a backup, CCW and ACW MOVs and retum header MOVs can be isolated. ACW can be isolated.
SpatialEncets: Propagation EEected Location: TAB, YARD Spatial EKects Comments: Turbine auxiliary building prnpag=* into turbine buiMing with pa*=tial impacts on power conversion system and its support sysems.
Initiating Event: I Initiating EventID: T7 Initiating Event Recovery: Potential flow diversion of both trams is assumed. Isolation success restores both safety related headers with loss of CCW (RCP cooling and auxilianes) and ACW.
Loss of System: S SystemIPEID: PCS System Recovery: Loss of power conversion system (PCS) is assumed either due to floodmg or isolation.
Loss of Train: TM-#2 TrainID: SW Header #1 and #2 Train Recovery: Loss of both headers due to flow diversion until isolation. See Initiatmg Event Recovery.
(O Consequence Comments: Consequence is " Medium" based on Table 2-3 with 2 backup trains (EFW and once through cooling). For the failure to isolate case, there are 2 backup trams (because break is outside RAB,2 opportunities to fail isolation and/or recover EFW or AFW or once through cooling).
Consequence Category: MEDIUM O
ano_swl. doc 3/26/98
1 Page 89 1
Calculation No. NSD-023 Consequence ID: SW-C-12A Consequence
Description:
CCW & ACW Retum Connection & Return Header #1 in Rooms 2081 &
2040 up to 2CV-1481-1 During Operation (2HBC-50-16 & 18 in Rooms 2081 and 2040,2HBC-59-16 in Room 2040,2HBC-77-12 in Room 2040,2HBC-75 8 in Room 2040,2HBC-81-12 in Room 2040,2HBC-88-42 in Room 2081)
Break Size: Iarge Isolability of Break: Yes ISO Comments: 2CV-1543-1 will isolate flow fan CCW and ACW; these sources can also be isolated up stream of this valve. Other service water loads that discharge into this retum header must also be isolated or the whole service water header isolated. Also,2CV-1481-1 must be isolated to prevent back flow from Header #2. Loss of Header #1 can be assumed due to isolation. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection. Also, auxiliary building sump alarms provide detection.
SpatialEffects: Propagation Effected Location: Room 2081 & 2040 Spatial Effects Comments: Room 2081 pic g== into Room 2040. Room 2040 propagation is to El -
317 (Rooms 2006 & 2011) through floor drains and east stairway. Room 2040 is a very large floor area, but eventually water could accumulate and fail MCC 2B52. He MCC is assumed fail before isolation if the break is in the.
main supply or return benders (i.e., very high flow rates). The MCC fails Train A ECCS valves including CSS Valves 2CV-5612-1 and 2CV-5649-1 (Sump Recirculation A). An unisolated break would eventually fill El 317 and
' ' " ' ' ' " ~ ' ' " ' ' ' ' ' " ' ' ' " ' ' ' ' " " " ' ' " ' ' ' " '"' ' "'
C) 2007,2010, & 2014).
Initiating Event: I Initiating Event ID: T7 Initiating Event Recovery: Potential flow diversion of both trains is assumed. Isolation success restores both safety related headers with loss of CCW (RCP cooling and auxiliaries).
Loss of System: SM-2 SystemIPEID: CCW, ACW System Recovery: CCW and ACW are lost due to isolation as well as systems et on these -
systems (loss of power conversion system can be assumed).
Loss of Train: TM-2 Train ID: SW Header #1 and #2 Train Recovery: Loss of both headers due to flow diversion until isolation. See Inhiding Event Recovery.
Consequence Comments: Consequence is "High" for the failure to isolate case based on Table 2-3 with I backup train (isolation). Successful isolation is a " Medium" based on Table 2-3 with 2 backup trams (EFW A and I train of once through cooling). Pipe 2HBC-88-42 in Room 2081 is included with this consequence (it is assumed that pipe failure on demand is not detectable before flooding ECCS).
Consequence Category: HIGH ano_swl. doc 3/26/98 j
Page 90 Calculation No. NSD-023 Consequence ID. SW C-12B Consequence
Description:
CCW & ACW Retum Cnnaa-tion & Return Header #2 in Rooms 2081 &
2040 up to 2CV-1480-2 Durir.g Operation (2HBC-51-16 & 18 in Rooms 2081 and 2040,2HBC-60-16 in Room 2040,2HBC-78-12 in Room 2040,2HBC-
. 76-8 in Room 2040,2HBC-81-12 in Room 20<0)
Break Size: Large Isolability of Break: Yes ISO Comments: 2CV-1542-2 will isolate flow from CCW and ACW; these sources can also be isolated up stream of this valve. Other service water loads that discharge into this retum header must also be isolated or the whole service water header isolated. Also,2CV-1480-2 must be isolated to prevent back flow from Header #1. less of Header #2 can be assumed due to isolation. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection. Also, auxiliary building sump alarms provide detecuan Spatial EKects: Propagation Effected Location: Room 2081 & 2040 Spatial Effects Comments: Room 2081 propagates into Room 2040. Room 2040 propagation is to El 317 (Rooms 2006 & 2011) through floor drains and cast stairway. Room 2040 is a very large floor area, but eventually water could accumulate and fail MCC 2B52. The MCC is assumed fail before isolation if the break is in the main supply or return headers (i.e., very high flow rates). *Ibe MCC fails Train A ECCS valves including CSS Valves 2CV-5612-1 and 2CV-5649-1 (Sump Recirculation A). An unisolated break would eventually fill El 317 and it is assumed that all ECCS equipment is flooded (propagation into rooms O
2007, 2010, & 2014).
Initiating Event: I Initiating Event ID: T7 Initiating Event Recovery: Potential flow diversion of both trams is assumed, Isolation success restores both safety related headers with loss of CCW (RCP cooling and auxiliaries).
Loss of System: SM-2 System IPE ID: CCW,ACW System Recovery: CCW and ACW are lost due to isolation as well as systems sir =*=t on thesc systems (loss of power conversion system can be assumed).
Loss of Train: TM-2 Train ID: SW Header #1 and #2 Train Recovery: less of both headers due to flow diversion until isolation. See Initiatmg Event Recovery.
Consequence Comments: Consequence is "High" based on Table 2-3 with less than 2 backup trams (EFW B). For the failure to isolate case, there is 1 backup train (failure to isolate).
Consequence Category: HIGH l
O ano_swl. doc 3/26/98
Page 91 -
Calculation No. NSD-023 Consequence ID: SW-C-13 Consequence
Description:
C= man Retum Dow..heT. of 2CV-1481-1 & 2CV-1480-2 in Room 2040 During Operation (2HBD-26-18,24 & 30 in Room 2040)
Break Size: Im ge Isolability of Break: Yes ISO Comments: Isolation of this break could result in total loss of service water. Closure of 2CV-1481-1 and 2CV-1480-2 (or 2CV-1460 for piping i,w Lwii of this valve), and opemng of 2CV-1541-1 and/or 2CV-1540-2 will restore service water headers. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection. Also, auxiliary building sump alarms provide detection.
~ Spatial Effects: Propagation Effected Location: Room 2040 Spatial Effects Comments: Propagation is to El 317 (Rooms 2006 & 2011) through floor drams and esst stairway. Room 2040 is a very large floor area, but eventually water could accumulate and fail MCC 2B52. The MCC is assumed fail before isolation if the break is in the main supply or return headers (i.e., very high flow rates).
The MCC fails Train A ECCS valves includmg CSS Valves 2CV-5612-1 and 2CV-5649-1 (Sump Recirculation A). An unisolated break would eventually fill El 317 and it is assumed that all ECCS equipment is flaaM (propagation into rooms 2007,2010, & 2014).
Initiating Event: I Initiating Event ID: T7 Initiating Event Recovery: Potential flow diversion of both trains is med Isolation success restores both safety related headers with loss of CCW (RCP cooling and auxiliaries).
Loss of System: SM-2 SystemIPEID: CCW, ACW System Recovery: CCW and ACW are assumed lost during event (loss of power conversion system can be assumed).
Loss of Train: TM-2 Train ID: SW Header #1 and #2 Train Recovery: Loss of both headers due to flow diversion until isolation. See Initiatung Event Recovery.
Consequence Comments: Consequenc6 is "High" for the failure to isolate case based on Table 2-3 with I backup train (1 solation). Successful isolation is a " Medium" based on Table 2-3 with 2 backup : rains (EFW and I train of once through cooling).
Consequence Category: HIGH 1
l O
ano_swl. doc 3/26/98
Page 92 Calculation No. NSD-023
) Consequence ID: SW-C-14A
/
Consequence
Description:
Supply Header #1 in Rooms 2006 and 2014 to ECCS Equipment During Operation (2HBC-35-16 & 14 upstream of 2CV-1453-1)
Break Size: Large Isolability of Break: Yes ISO Comments: Piping downstream of 2CV-1400-1 can be isolated, but isolation of header #1 at the intake is assumed (see spatial effects). Procedure 2203.022 provides direction to isolate based on low header pressure providing detection. Also, ECCS pump room floor drain alanns provide detection.
SpatialEffects: Propagation Effected Location: Room 2006 & 2014 Spatial Effects Comments: Since 2CV-1400-1 is a few feet off the floor in Room 2006, no credit is alloud for its isolation of the break. Eventually propagation will occur into the train B & C ECCS equipment rooms (Rooms 2007 and 2010) if the break is not isolated; this would result in loss of all ECCS. He ECCS rooms are protected by water tight doors.
Initiating Event: I Initiating Event ID: T8 Initiating Event Recovery: Flow diversion of header #1 and its loss when 2P-4A or 4B is stopped; service water header #1 is assumed not recovered in this analysis. Since there is flow through this piping during normal operation, this configuration is analyzed up to normally closed 2CV-1453-1 (piping downstream is evaluated Loss of System: S SystemIPEID: CCW, ACW System Recovery: It is possible that CCW and/or ACW could be isolated, but it could also be recovered.
i Loss of Train: T Train ID: SW Header #1 Train Recovery: If 2CV-1400-1 can be isolated (e.g., locally), header I with the exception of ECCS equipment cooling can be recovered. His is not credited in the analysis.
Consequence Comments: Consequence is " Medium"liased on Table 2-3 with 2 backup trains (EFW A, I train of once through cooling, & possibly PCS or AFW). For the failure to isolate case, there are 2 backup trams (failure to isolate, EFW A, & possibly PCS or AFW).
Consequence Category: MEDIUM l
l Db ano_swl. doc 3/26/98
Page 93 Calculation No. NSD-023 Consequence ID: SW-C-14B Consequence
Description:
Supply Header #2 in Rooms 2006 and 2007 to ECCS Equipment Dunng Operation (2HBC-43-16 & 14 upstream of 2CV-1456-2)
BreakSize: Large Isolability of Break: Yes ISO Comments: His piping can be isolated with 2CV-1406-2 in Room 2040. Header #2 at the intake can also be isolated. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection. Also, ECCS pump room floor drain alarms provide detection.
h SpatialEffects: Propagation EEccted Location: Room 2006 & 2007 Spatial Effects Comments: Eventually propagation will occur into the train A & C ECCS equipment rooms (Rooms 2014 and 2010) if the break is not isolated; this would result in loss of all ECCS. The ECCS rooms are protected by water tight doors.
Initiating Event:.I Initiating Event ID: T9 Initiating Event Recovery: Flow diversion of header #2 until it is isolated. Isolation results in loss of ECCS train B equipment cooling; service water header #2 is assumed not recovered in this analysis. Since there is flow through this piping during normal operation, this configuration is analyzed up to normally closed 2CV-1456-2 (piping downstream is evaluated for accident demand).
Loss ofSystem: S SystemIPEID: CCW, ACW System Recovery: It is possible that CCW and/or ACW could be isolated, but it could also be recovered.
- Loss of Train: T Train ID: SW Header #2 Train Recovery: If 2CV-1406-2 is isolated, header 2 with the exception of ECCS equipment cooling can be recovered. His is not credited in the analysis.
Consequence Comments: Consequence is " Medium" based on Table 2-3 with 2 backup trams (EFW B,1 train of once through cooling, & possibly PCS or AFW). For the failure to isolate case, there are 2 backup trains (failure to isolate, EFW B, & possibly PCS or AFW)
Consequence Category: MEDIUM j
I O
l ano_swl. doc 3/26/98
Page 94 Calculation No. NSD-023 Consequence ID: SW-C-15A Consequence
Description:
ECCS Return Header #1 Downstream of 2CV-1453-1 on Demand in Rooms 2014 and 2006 (2HCC-294-14 & 2HBC-59-14 & 16) -
Break Size: Large Isolability of Break: Yes ISO Comments: 2CV-1453-1 can be closed or 2CV-1400-1 can be isolated or header #1 can be isolated at the intake. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection. Also, ECCS pump room floor drain alanns provide detection.
Spatial EKecM: Propagation Effected Location: Room 2006 & 2014 Spatial EKects Comments: Since 2CV-1400-1 is a few feet ott de. floor in Room 2006, no crecht is allowed for its isolation of the break. 2CV-1453-1 is at least 5 feet above the floor and may also be flooded before isolation occurs. Eventually propagation will occur into the train B & C ECCS equipment rooms (Rooms 2007 and 2010) if the break is not isolated; this would result in loss of all ECCS. 'Ibe ECCS rooms are protected by water tight doors.
Initiating Event: N Initiating Event ID: LOCA Initiating Event Recovery: It is assumed that pipe break occurs during a LOCA accident demand which opens 2CV-1453-1.
Loss of System: S SystemIPEID: CCW, ACW System Recovery: CCW and ACW (power conversion system) are assumed unavailable due to LOCA whichisolates these systems Loss of Train: T Train ID: SW Header #1
)
Train Recovery: If 2CV-1400-1 or 2CV-1453-1 can be isolated, header 1 with the exception of ECCS equipment cooling can be recovered. 'Ihis is not credited in the analysis; header #1 is assumed unavailable.
Consequence Comments: Consequence is " Medium" based on Table 2-2: unexpected frequency of challenge, between tests exposure, and I backup train (ECCS train B). For the failure to isolate case (all ECCS failure), it is assumed that failure to isolate is i
worth a backup train.
Consequence Category: MEDIUM O
ano,,swl. doc 3/26/98 -
Page 95 Calculation No. NSD-023 Consequence ID: SW-C-ISB Consequence
Description:
ECCS Return Header #2 Downstream of 2CV-1456-2 on Demand in Rooms 2007 and 2006 (2HCC-295-14 & 2HBC-60-14 & 16)
Break Size: Large Isolability of Break: Yes ISO Comments: 2CV-1456-2 can be closed or 2CV-1406-2 can be isolated or header #2 can be isolated at the intake. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection. Also, ECCS pump room floor drain alarms provdt detection.
SpatialEffects: Propagation Effected Location: Room 2006 & 2007 Spatial Effects Comments: Since 2CV-1406-2 is in Room 2040,2CV-1456-2 is at least 5 feet above the floor and may be flooded before isolation occurs. Eventually propagation will occur into the train A & C ECCS equipment rooms (Rooms 2014 and 2010) if the break is not isolated; this would result in loss of all ECCS. 'Ihe ECCS rooms are protected by water tight doors.
Initiating Event: N Initiating Event ID: LOCA Initiating Event Recovery: It is assumed that pipe break occurs during a LOCA accident demand which
{
opens 2CV-1456-2.
Loss of System: S SystemIPEID: CCW, ACW S
CCW and ACW (power conversion system) are assamed unavailable due to LOCA O
ystem Recovery:
which isolates these systems Loss of Train: T Train ID: SW Header #2 Train Recovery: If 2CV-1406-2 -r ; CV-1456-2 can be isolated, header 2 with the exception of ECCS equipment cooling can be recovered. This is not credited in the analysis; header #2 is assumed unavailabic.
Consequence Comments: Consequence is " Medium" based on Table 2-2: unerp~i frequency of challenge, between tests exposure, and 1 backup train (ECCS train A). For the failure to isolate case (all ECCS failure), it is assumed that failure to isolate is worth a backup train.
Consequence Category: MEDIUM s
c
' ano_swl. doc 3/26/98
Page 96 Calculation No. NSD-023 Consequence ID: SW-C-16A Consequence
Description:
Containment Cooling From Header #1 in Room 2055 During Operation (2HBC-68-12 in Room 2055)
Break Size: Large Isolability of Break: Yes ISO Comments: Stop pump 2P-4A or 4B (depends on which one is operating) and if aligned to ACW system, close either 2CV-1418-1 or 2CV-1419-1. Procedure 2203.022 provides 3
direction to isolate based on low header pressure providing detection. Also, auxiliary building sump alarms provide detection.
Spatial Effects: Propagation Effected Location: Room 2055 Spatial Effects Comments: Room 2055 propagates to Room 2040 which propagates to El 317 (Rooms 2006 & 2011) through floor drams and cast stauway. Room 2040 is a very large floor area, but eventually water could accumulate and fail MCC 2B52, if unisolated. The MCC fails Train A ECCS valves including CSS Valves 2CV-5612-1 and 2CV-5649-1 (Sump Recirculation A). An unisolated break would eventually fill El 317 and it is assumed that all ECCS equipment is flooded (propagation irlo rooms 2007, 2010, & 2014).
Initiating Event: I Initiating Event ID: T8 l
Initiating Event Recovery: Ioss of 2P-4A and service water header #1 unavailable and assumed not recovered in this analysis. It is also assumed that this piping in standby (e.g.,
no flow) sees sufficient SW pressure to be challenged during normal O
operation.
Loss of System: S System IPE ID: NA System Recovery: CCW could be initially isolated per Procedure 2203.022, but could be recovered by the unaffected service water header. Also, if ACW is aligned, it would be isolated and could be recovered from the other unaffected header.
Loss of Train: T Train ID: SW Header #1 Train Recovery: See Initiating Event Recovery.
Consequence Comments: Consequence is " Medium" based on Table 2-3 with 2 backup trains (EFW A, I train of once through cooling, & possibly PCS or AFW). For the failure to isolate case, there are 2 backup trams (failure to isolate, EFW A, & possibly PCS or AFW)
Consequence Category: MEDIUM O
ano_swl. doc 3/26/98
Page 97 Calculation No. NSD-023 Consequence ID:SW-C-16B l
Consequence
Description:
Containment Cooling From Header #2 in Room 2081 During Operation (2HBC-69-12 in Room 2081 up to 2CV-1513-2) l Break Size: Large Isolability of Brealc Yes ISO Comments: Stop pump 2P-4C or 4B (depends on which one is operating) and if aligned to ACW l
system, close either 2CV-1422-2 or 2CV-1421-2. Procedure 2203.022 provides direction to isolate based on low header pressure provuhng d-'~+ian Also, auxahary l
building sump alarms provide detection.
SpatialEffects: Propagation Effected Location: Room 2081 Spatial Effects Comments: Room 2081 propagates to Room 2040 which prw to El 317 (Rooms 2006 & 2011) through floor drams and east stairway. Room 2040 is a very l
large floor area, but eventually water could accumulate and fail MCC 2B52, if unisolated 'Ihe MCC fails Train A ECCS valves including CSS Valves 2CV-5612-1 and 2CV-5649-1 (Sump Recirculation A). An unisolated break would eventually fill El 317 and it is assumed that all ECCS equipment is j
flooded (propagation into rooms 2007,2010, & 2014).
Initiating Event: I Initiating Event ID: T9 l
Initiating Event Recovery: Loss of 2P-4C and service water header #2 unavailable and assumed not recovered in this analysis. It is also assumed that c-M piping in standby (e.g., no flow) sees sufficient SW pressure to be challenged during normal O
Loss of System: S System IPE ID: NA System Recovery: CCW could be initially isolated per Procedure 2203.022, but could be recovend by the unaffected service water header. Also, if ACW is ahgned, it would be isolated and could be recovered from the other unnhM header.
Loss ofTrain: T TrainID: SWHeader#2 Train Recovery: See Initiating Event Recovery.
' Consequence Comments: Consequence is " Medium" based on Table 2-3 with 2 backup trams (EFW B,1-train of once through cooling, & possibly PCS or AFW). For the failure to isolate case, there are 2 backup trains (failure to isolate, EFW B, & possibly PCS or AFW).
l Consequence Category: MEDIUM
\\
l O
ano_swl. doc 3/26/98
Page 98 Calculation No. NSD-023 Consequence ID: SW-C-17 Consequence
Description:
Containment Cooling From Header # 1 in Room 2084 During Operation (2HBC-68-12 in Room 2084 up to 2CV-1511-1)
Break Size: Large Isolability of Break: Yes ISO Comments: Stop pump 2P-4A or 4B (depends on which one is operatmg) and if aligned to ACW system, close either 2CV-1418-1 or 2CV-1419-1. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection. Also, auxiliary building sump alanns provide detection.
Spatial Effects: Propagation Effected Location: Room 2084 Spatial Effects Comments: Room 2084 prapag=*~ to Room 2073 which easily propagates down to Room 2040 through floor grating. Also floor drams propagate to El 317.
Room 2040 propagates to El 317 (Rooms 2006 & 2011) through floor drains and cast stairway. Room 2040 is a very large floor area, but eventually water could accumulate and fail MCC 2B52, if unisolated. 'Ihe MCC fails Train A ECCS valves including CSS Valves 2CV-5612-1 and 2CV-5649-1 (Sump Recirculation A). An unisolated break would eventually fill El 317 and it is assumed that all ECCS equipment is flooded (propagation into rooms 2007, 2010, & 2014).
- Initiating Event: I Initiating Event ID: T8 Initiating Event Recovery: Loss of 2i-4A and service water header #1 unavailable and assumed not f-recovered in this analysis. It is also assumed that this piping in standby (e.g.,
no flow) sees sufficiert: SW pressure to be challenged during normal operation.
Loss of System: S SystemIPEID: NA System Recovery: CCW could be initially isolated per Procedure 2203.022, but could be recovered by the unaffected service water header. Also, if ACW is aligned, it would be isolated and could be recovered from the other unaffected header.
Loss of Train: T Train ID: SW Header #1 Train Recovery: See Initiating Event Recovery.
Consequence Comments: Consequence is "Mediurri' based on Table 2-3 with 2 backup trains (EFW A, I train of once through cooling, & possibly PCS or AFW). For the failure to isolate case, there are 2 backup trains (failure to isolate, EFW A, & possibly PCS or AFW)
Consequence Category: MEDIUM O
ano,_swl. doc 3/26/98
Page 99 Calculation No. NSD-023 Consequence ID: SW-C-18A Consequence
Description:
Containment Cooling A During LOCA Demand (2HBB-2-12)
BreakSize: Large Isolability of Break: Yes ISO Comments: Close 2CV-1511-1 results in loss of train A contamment cooling. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection. Auxiliary building sump alarms provide detection as well as contamment coe!!ng return low flow.
SpatialEffects: Propagation Effected Location: Room'2084 Spatial EfTects Comments: Room 2084 propey;es to Room 2073 which easily propagates down to Room 2040 through floor grating. Also floor drams propagate to El 317.
Room 2040 picp - " to El 317 (Rooms 2006 & 2011) through floor drains and east stairway. Room 2040 is a very large floor area, but eventually water could accumulate and fail MCC 2B.*2, if unisolated. The MCC fails Train A ECCS valves including CSS Mes 2CV-5612-1 and 2CV-5649-1 (Sump Reciculation A). An unisolated break would eventually fill El 317 and it is assumed that all ECCS equipment is flooded (propagation into rooms 2007, 2010, & 2014).
Initiating Event: N Initiating Event ID: LOCA Initiating Event Recovery: It is assumed that pipe break occurs during a LOCA accident demand which opens 2CV-1511-1.
Loss of System: S-SystemIPEID: NA System Recovery: CCP and ACW (power conversion system) are assumed unavailable due to LOCA which isolates these systems Loss of Train: T Train ID: SW Header #1 Train Recovery: SW header #1 is lost due to flow diversion until break is isolated. Isolation leads to loss of contamment cooling train A.
Consequence Comments: Failure to isolate results in a " Medium" consequence based on Table 2-2:
unexpected frequency of challenge, between tests exposure, and ! backup train (isolation). Successful isolation is a "Im" Consequence based on Table 2-2 with 2 backup trains (both ECCS trains).
Consequence Category: MEDIUM ano swl. doc 3/26/98
Page 100 Calculation No. NSD-023 Consequence ID: SW-C-18B Consequence
Description:
C*=ia-at Cooling B During LOCA Demand (2HBB-3-12)
BreakSize: Large Isolability of Break: Yes ISO Comments: Closing 2CV-1510-2 results in loss of train B contamment cooling. Procedure 2203.022 provides direction to isolate based on low header pressure provximg datartum Auxiliary building sump alarms provide detection as well as contamment coohng return low flow.
SpatialEffects: Propagation Effected Location: Room 2081 Spatial Effects Comments: Room 2081 prapag=*a= to Room 2040 which propagates to El 317 (Rooms 2006 & 2011) through floor drains and cast stairway. Room 2040 is a very large floor area, but eventually water could accumulate and fail MCC 2B52, if unisolated. 'Ihe MCC fails Train A ECCS valves including CSS Valves
~ 2CV-5612-1 and 2CV-5649-1 (Sump Recirculation A). An unisolated break would eventually fill El 317 and it is assumed that all ECCS equipment is.
flooded (propagation into rooms 2007, 2010, & 2014).
Initiating Event: N Initiating EventID: LOCA Initiating Event Recovery: It is assumed that pipe break occurs during a LOCA accident demand which opens 2CV-1510-2.
Loss of System: S SystemIPE ID: NA System Recovery: CCW and ACW (power conversion system) are assumed unavailable due to LOCA whichisolates these systems Loss of Train: T
. Train ID: SW Hender #2 i
Train Recovery: SW header #2 is lost due to flow diversion until break is isolated. Isolation leads to loss of contamment cooling train A.
Consequence Comments: Failure to isolate resuhs in a " Medium" consequence based on Table 2-2:
l unexpected frequency of challenge, between tests exposure, and I backup train (isolation). Successful isolation is a "I.ow" C==~mence based on Table 2-2 with 2 backup trains (both ECCS trams).
Consequence Category: MEDIUM l
hv l
I ano_swl. doc 3/26/98
1 Page 101 Calculation No. NSD-023 Consequence ID: SW-C-19A Consequence
Description:
Containment Cooling A During LOCA Demand Inside Contamment (2HBC-103 and 105)
Break Size: Large Isolability of Break: Yes ISO Comments: Close 2CV-1511-1 results in loss of train A contamment cooling. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection.
Creainment cooling retum low flow alarm also provides detection.
I SpatialEffects: Contamment Effected Location: Contahunent Building Spatial Effects Comments: No flooding mpacts on LOCA mitigation have been identified inside i
containment.
Initiating Event: N Initiating Event ID: LOCA Initiating Event Recovery: It is assumed that pipe break occurs during a LOCA accident demand which opens 2CV-1511-1.
Loss of System: S SystemIPEID: NA System Recovery: CCW and ACW (pow:r conversion system) are assumed unavailable due to LOCA which isolates these systems.
Loss of Train: T Train ID: SW Header #1
('
Train Recovery: SW header # 1 is lost due to flow diversion until break is isolated. Isolation leads to loss of containment cooling train A.
Consequence Comments: Consequence is " Low" based on Table 2-2: unexpected frequency of challenge, between tests exposure, and 2 backup trams (ECCS trams A & B). For the failure to isolate case (loss of I header which leads to loss of 1 ECCS train),
there are still 2 backup trains (failure to isolate plus 1 ECCS train).
Consequence Category: LOW O
ano_swl. doc 3/26/98
Page 102 Calculation No. NSD-023 Consequence ID: SW-C-19B
\\
Consequence
Description:
Containment Cooling B During LOCA Demand Inside Contamment (2HBC-104 and 106)
Break Size: Large Isolability of Break: Yes ISO Comments: Close 2CV-1510-2 results in loss of train B contamment cooling. Procedure 2203.022 provides direction to isolate based on low header pressure provxhng detection.
Contamment cooling return low flow alarm also provides detection.
SpatialEffects: Contamment Effected Location: Contamment Building Spatial Effects Comments: No flooding impacts on LOCA mitigation have been identified inside contamment.
Initiating Event: N Initiating Event ID: LOCA Initiating Event Recovery: It is assumed that pipe break occurs during a LOCA accident demand v Mch opens 2CV-1510-2.
Loss of System: S System IPE ID: NA System Recovery: CCW and ACW (power conversion system) are assumed unavailable due to LOCA which isolates these systems.
Loss of Train: T Train ID: SW Header #2 Train Recovery: SW header #2 is lost due to flow diversion until break is isolated. Isolation leads to loss
\\
of contamment cooling train B.
Consequence Comments: Consequence is " Low" based on Table 2-2: unexpected frequency of challenge, between tests exposure, and 2 backup trams (ECCS trains A & B). For the failure to isolate case (loss of I header which leads to loss of 1 ECCS train),
there are still 2 backup trams (failure to isolate plus 1 ECCS train).
Consequence Category: LOW O
ano swl. doc 3/26/98
Page 103 Calculation No. NSD-023 Consequence 1D: SW{-20A Consequence Bescription: C"=3aw Cooling A Return During LOCA Demand (2HBB-4-12 & 2HBC-77-12 in Rooms 2084 & 2055)
Break Size: Large Isolability of Break: Yes ISO Conuments: Closing 2CV-1511-1 isolates break and results in loss of train A containment cooling.
2CV-1519-1 can also be closed for piping downstream of this valve. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection.
Auxthary building sump alarms provide detection as well as containment cooling return low flow.
SpatialEffects: Propagation Effected Location: Room 2084 & 2055 Spatial Effects Comments: Room 2084 pranag='~ to Room 2073 which usily pic-;=? down to Room 2040 through floor gratmg. Also floor drams propagate to El 317.
Room 2055 pranag='~ directly to Room 2040. Room 2040 propagates to El 317 (Rooms 2006 & 2011) through floor drains and east stairway. Room 2040 is a very large floor area, but eventually water could accumulate and fail -
MCC 2B52, if unisolated. 'Ihe MCC fails Train A ECCS valves including CSS Valves 2CV-5612-1 and 2CV-5649-1 (Sump Recirculation A). An unisolated break would eventually fill El 317 and it is assumed that all ECCS equipment is flooded (propagation into rooms 2007,2010, & 2014).
Initiating Event: N Initiating Event ID: LOCA O
Initiating Event Recovery: It is assumed that pipe break occurs during a LOCA accident demand which opens 2CV-1511-1.
Loss ofSystem: S System IPEID: NA System Recovery: CCW and ACW (power conversion system) are assumed unavailable due to LOCA whichisolates these systems Loss of Train:' T Train ID: SW Header #1 Train Recovery: SW header #1 is lost due to flow diversion until break is isolated. Isolation leads to loss of contamment cooling train A.
Consequence Comments: Failure to isolate results in a " Medium" consequence based on Table 2-2:
unexpected frequency of challenge, between tests exposure, and I backup train (isolation). Successful isolation is a "Im" Consequence based on Table 2-2 with 2 backup trams (both ECCS trams).
Consequence Category: MEDIUM O
ano_swl. doc 3/26/98
. Page 104 Calculation No. NSD-023 G ConsequenceID:SW-C-208 b
Consequence
Description:
Cet Cooling B Retum During LOCA Demand (2HBB-5-12 and 2HBC-78-12 in Room 2081)
Break Size: Large Is > lability of Break: Yes ISO Comments: Closing 2CV-1510-1 isolates break and results in loss of train B contamment cooling.
2CV-1513-2 can also be closed for piping downstream of this valve. Procedure 2203.022 provides ducction to isolate based on low header pressure providing detection.
Auxiliary building sump alanns provide detection as well as contamment coolmg return low flow.
SpatialEffects: Propagation Effected Location: Room 2081 Spatial Effects Comments: Room 2081 prapag=*~ to Room 2040 which prapag='~ to El 317 (Rooms 2006 & 2011) through floor drams and east stairway. Room 2040 is a very q
large floor area, but eventually water could accumulate and fail MCC 2B52, if unisolated. The MCC fails Train A ECCS valves including CSS Valves 2CV-5612-1 and 2CV-5649-1 (Sump Recirculation A). An unisolated break 3
i would eventually fill El 317 and it is =sW that all ECCS equipment is flooded (propagation into rooms 2007, 2010, & 2014).
Initiating Event: N Initiating Event ID: LOCA Initiating Event Recovery: It is assumed that pipe break occurs during a LOCA accident demand which opens 2CV-1510-2.
Loss of System: S SystemIPEID: NA System Recovery: CCW and ACW (power conversion system) are assumed unavailable due to LOCA which isolates these systems Loss of Tesin: T Train ID: SW Header #2 Train Recovery: SW header #2 is lost due to flow diversion until break is isolated. Isolation leads to loss of contamment cooling train A.
Consequence Comments: Failure to isolate results in a " Medium" consequence based on Table 2-2:
unexpected frequency of challenge, between tests exposure, and I backup train (isolation). Successful isolation is a "Imv" Consequence based on Table 2-2 with 2 backup trains (both ECCS trains).
Consequence Category: MEDIUM O
ano_swl. doc 3/26/98
Page 105 Calculation No. NSD-023 Consequence ID: SW-C-21 A Consequence
Description:
Control Room & EDG Coolmg From Header #1 in Room 2073 During Operation (2HBC-63-8 in Ro 2073) -
Break Size: large Isolability cf Break: Yes ISO Comments: Manual valve 2SW-14.5A in Room 2040 can be closed. As a backup, pump 2P-4A or 4B (depends on which one is operating) could be stopped and recovered after local isolation. Procedure 2203.022 provides direction to isolate trased op %w header pressure providing detection. Also, auxiliary building sump alarms provide t.cv., tion.
SpatialEffects: Propagation Effected Location: Room 2073 Spatial Effects Comments: Room 2073 easily propagates down to Room 2040 through floor gratmg Also floor drams propagste to El 317. Room 2040 prr=ge~ to El 317 (Rooms 2006 & 201' Vough floor drams and east stairway. Room 2040 is a very large floor area, but eventually water could accumulate and fail MCC 2B52 if unisolated. An unisolated break would eventually fill El 317 and it is assumed that all ECCS equipment is flooded (propagation into rooms 2007, 2010, & 2014).
Initiating Event: I Initiating Event ID: T8 Initiating Event Recovery: Loss of service water header #1 due to flow diversion or initial stop of 2P-4A.
Isolation of break recovers main header, but EDG and Control Room emergency cooling is unavailable.
Loss of System: S System IPE ID: NA System Recovery: CCW could be initially isolated per Procedure 2203.022, but could be recovered by the unaffected service water header.
Loss of Train: T Train ID: SW Header #1 Train Recovery: See Initiating Event Recovery.
Consequence Comments: Consequence is " Medium" based oo Table 2-3 with 2 backup trams (EFW A, once through cooling, & possible PCS or AFW). For the failure to isohte case, there are 2 backup trams (failure to isobte, EFW A, & possible PCS or AFW)
Consequence Category: MEDIUM 1
l O
ano_,swl. doc 3/26/98
I Page 106 Calculation No. NSD-023 Consequence ID: SW-C-21B Consequence
Description:
Control Room & EDG Cooling From Header #2 in Room 2073 During Operation (2HBC-64-8 in Room 2073)
Break Size: Large Isolability of Break: Yes ISO Comments: Manual valve 2SW-143B in Room 2040 can be closed. As a backup, pump 2P-4C or 4B (depends on which one is operstmg) could be stopped and recovered aRer local isolation Procedure 2203.022 provides direction to isolate based on low header pressure provuhng detection. Also, auxiliary building samp alarms provide detection.-
SpatialEffects: Propagation Effected Location: Room 2073 Spatial EfTects Comments: Room 2073 casily propagates down to Room 2040 through floor gratmg.
i Also floor drams propagate to El 317. Room 2040 prryay* to El 317 (Rooms 2006 & 2011) through floor drams and cast stauway. Room 2040 is a very large floor area, but eventually water could accumulate and fail MCC I
2B52 if unisolated. An unisolated break would eventually fill El 317 and it is assumed that all ECCS equipment is flooded (propagation into rooms 2007, 2010, & 2014).
Initiating Event: I Initiating Event ID: T9 Initiating Event Recovery: Iais of service water header #2 due to flow diversion or initial stop of 2P 4C.
Isolation of break recovers main header, but EDG and Control Room amergency cooling is unavailable.
g Loss of System: S System IPE ID: NA System Recovery: CCW could be initially isolated per Procedure 2203.022, but could be recovered by the
==#W service water header.
i Loss of Train: T Train ID: SW H;.ader #2 Train Recovery: See Initiating Event Recovery.
Consequence Comments: Consequence is " Medium" based on Table 2-3 with 2 backup trams (EFW B, once through cooling, & possible PCS or AFW). For the failure to isolate case, there are 2 backup trains (failure to isolate, EFW B, & possible PCS or AFW)
Consequence Category: MEDIUM O
ano_swl. doc 3/26/98
Page 107 Calculation No. NSD-023 Consequence ID: SW-C-22A Consequence
Description:
EDG Cooling From Header #1 During LOSP Demand (2HBC-63-8 and 2HBC-75-8 in Room 2093)
BreakSize: Large Isolability of Bresk: Yes ISO Comments: Manual valve 2SW-143A in Room 2040 can be closed and there are other manual valves in Rooms 2073 and 2093. As a backup, pump 2P 4A e G (depends on which one is operstmg) could be stopped and recovered after local isolation. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection. Also, there is an intrusion alarm and flood alarm for each EDG Room and auxiliary buildmg sump alarms provide detection.
Spatial Effects: Propagation Effected Location: Room 2093 Spatial Effects Comments: The EDG can be assumed unavailable from flooding. The EDGs are lented at El 369 with surrounding rooms at El 374-6 and 372. A water tight door is provided for access between EDG rooms and the corridor entrance to the north room. Here is a 5 inch curb at the south room corridor entrance. Acccnig to PRA Flooding study, propagation is down through stairway and floor drains to El 317 (Room 2006 & 201!).
Initiating Event: N Initiating Event ID: LOSP Initiating Event Recovery: It is assumed that pipe break occurs during a LOSP accident demand which opens downstream valve 2CV-1503-1.
O Loss ofSystem: N System IPE ID: NA System Recovery: NA Loss of Train: T Train ID: SW Header #1 Train Recovery: SW header #1 is lost due to flow diversion until break is isolated. Isolation leads to loss of EDG and Control Room cooling train A.
Consequence Comments: Consequence is " Medium" based on Table 2-2: ufrequent frequency of challenge, betww tests exposure, and I backup train (EDG and LOSP recovery). For the failure to isolate case, there is at least I backup (fail to isolate).
Consequence Category: MEDIUM i
l i
l O
ano swl. doc 3/26/98
Page 108 Calculation No. NSD-023 Consequence ID: SW-C-22B Consequence
Description:
EDG Cooling From Header #2 During LOSP Demand (2HBC-64-8 and 2HBC-76-8 in Room 2094)
Break Size: Large Isolability of Break: Yes ISO Comments: Manual valve 2SW-143B in Room 2040 can be closed and there are other manual valves in Rooms 2073 and 2094.. As a backup, pump 2P-4C or 4B (depends on which one is -
operatmg) could be sicpped and recovered after local isolation. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection. Also, there is an intrusion alarm and flood alarm for each EDG Room and auxiliary building sump alarms provide detection.
SpatialEffects: Propagation Effected Location: Room 2094 Spatial Effects Comments: ne EDG can be assumed unavailable from floodmg. The EDds are located at El 369 with surroundmg rooms at El 374 6 and 372. A water tight door is provided for access betw. EDG rooms and the corridor entrance to the north room. Dere is a 5 inch curb at the south room corridor entrance. According to PRA Flooding study, propagation is down through stairway and floor drains to El 317 (Room 2006 & 201I).
Initiating Event: N Initiating Event ID: LOSP Initiatinig Event Recovery: It is assumed that pipe break occurs during a LOSP accident demand which opens downstream valve 2CV-1504-2.
O Loss of System: N SystemIPEID: NA System Recovery: NA Loss of Train: T Train ID: SW Header #2 Train Recovery: SW header #2 is lost due to flow diversion until break is isolated. Isolation leads to loss of EDG and Control Room cooling train B.
Consequence Comments: Consequence is " Medium" based on Table 2-2: mfrequent frequency of challenge, between tests exposure, and I backup train (EDG and LOSP recovery). For the failure te isolate case, there is at least I backup (fail to isolate).
Consequence Category: MEDIUM j
i 1
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Page 109 Calculation No. NSD-023
(
Consequence !D: SW-C-23A Consequence Descrip6 a, NOQ Cooling Retum up to 2CV-1503-1 During LOSP Demand (2HBC-75-8 m Room 2073 up to 2CV-1503-1)
Break Size: Luc Isolability of Break: Yes ISO Comments: Maal valve 2SW-143A in Room 2040 can be closed and there are other manual valves in Rooms 2073 and 2093. As a backup, pump 2P-4A or 4B (depends on which one is operating) could be stopped and recovM aaer local isolation. Procedure 2203.022 provides direction to isolate based on low headei pressure providing detection. Also, auxiliary building sump alarms provide detection.
Spatial Effects: Propagation Effected Location: Room 2073 Spatial Effects Comments: Room 2073 casily propagates down to Roon'. 2040 through floor gratmg Also floor drams propagate to El 317. Room 2040 propagates to El 317 (Rooms 2006 & 2011) through floor drains and cast stairway. Room 2040 is a very large floor area, but eventually wat:r could accumulate and fail MCC 2BS2 if unisolated. An unisolated break would eventually fill El 317 and it is assumed that all ECCS equipment is flooded (propagation into rooms 2007, 2010,&2014).
Initiating Event: N Initiating Event ID: LOSP Initiating Event Recovery: It is assumed that pipe break occurs during a LOSP accident demand which opens downstream valve 2CV-15031, V Loss of System: N System IPE ID: NA System Recovery: NA Loss of Train: T Train ID: SW Header #1 Train Recovery: SW header #1 is lost due to flow diversion until break is isolated. Isolation leads to ioss of EDG and Control Room cooling train A.
Consequence Comments: Consequence is " Medium" based on Table 2-2: infrequent frequency of challenge, between tests exposure, and I backup train (EDG and LOSP recovery). For the failure to isolate case, there is at least 1 backup ('hil to isolate).
Consequence Category: MEDIUM i
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Page 110 Calculation No. NSD-023 Consequence ID: SW C-23B Consequence
Description:
EDG Cooling Return up to 2CV-1504-2 During LOSP Demand (2HBC-76-8 in Room 2073 t.p to 2CV-1504-2)
BreakSize: Large Isolability of Break: Yes ISO Comments: Manual valve 2SW-143B in Room 2040 can be closed and there are other manual valves in Rooms 2073 and 2093. As a backup, pump 2P-4C or 4B (depends on which one is operating) could be stopped and recovered afler local isolation. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection. Also, auxiliary building sump alarms provide detection.
SpatialEfTects: Propagation EfTected Location: Room 2073 Spatial Effects Comments: Room 2073 casily propagates down to Room 2040 through floor gratmg Also floor drains propagate to El 317. Room 2040 propagates to El 317 (Rooms 2006 & 2011) through floor drams and east stairway. Room 2040 is a very large floor area, but eventually water could accumulate and fail MCC 2B52 if unisolated. An unisolated break would eventually fill El 317 and it is assumed that all ECCS equipment is flooded (propagation into rooms 2007, 2010, & 2014).
Initiating Event: N Initiating Event ID: LOSP Initiating Event Recovery: It is assumed that pipe break occurs during a LOSP accident demand witich opens downstream valve 2CV-1504-2.
O Loss ofSystem: N System IPE ID: NA System Recovery: NA Loss of Train: T TraiaID: SW Header #2 Train Recovery: SW header #2 is lost due to flow diversion until break is isolated. Isolation leads to loss of EDG and Control Room cooling train B.
Consequence Comments: Consequence is " Medium" based on Table 2-2: infrequent frequency of challenge, between tests exposure, and I backup train (EDG and LOSP recovery). For the failure to isolate case, there is at least I backup (fail to isolate).
Consequence Category: MEDIUM l
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Page111 Calculation No. NSD-023 Consequence ID: SW-C-24A Consequence
Description:
EDG Cooling Return downstream of 2CV-1503-1 During LOSP Demand (2HBC-75-8 in Room 2073 after 2CV-1503-1)
Break Size: Large Isolability of Break: Yes ISO Comments: Close 2CV-1503-1 or manual valve 2SW-143A in Room 2040 and there are other manual valves in Rooms 2073 and 2093. As a backup, pump 2P-4A or 4B (depends on which one is operating) could be stopped and recovered after local isolation. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection.
Also, auxiliary building sump alarms provide detection.
Spatial Effects: Propagation Effected Location: Room 2073 Spatial Effects Comments: Room 2073 easily propagates down to Room 2040 through floor gratmg.
Also floor drains propagate to El 317. Room 2040 propagates to El 317 (Rooms 2006 & 2011) through floor drains and cast stairway. Room 2040 is a very large floor area, but eventually water could accumulate and fail MCC 2B52 if unisolated. An unisolated break wouki eventually fill El 317 and it is assumed that all ECCS equipment is flooded (propagation into rooms 2007, 2010, & 2014).
Initiating Event: N Initiating Event ID: LOSP Initiating Event Recovery: It is assumed that pipe break occurs during a LOSP accident demand which Loss of System: N System IPE ID: NA System Recovery: NA Loss of Train: T Train ID: SW Header #1 Train Recovery: SW header #1 is lost due to flow diversion until break is isolated. Isolation leads to loss of EDG and Control Room cooling train A.
Consequence Comments: Consequence is " Medium" based on Table 2 2: mfrequent frequency of challenge, between tests exposure, and I backup train (EDG and LOSP recovery). For the failure to isolate case, there is at least 1 backup (fail to isolate).
Consequence Category: MEDIUM l
l l
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Page 112 Calculation No. NSD-023 Consequence ID: SW C-24B Consequence
Description:
EDG Cooling Retum downstream of 2CV-1504-2 During LOSP Demand (2HBC-76-8 in Room 2073 after 2CV-1504-2)
Break Size: Large Isolability of Break: Yes ISO Conunents: Close 2CV-1504-2 or manual valve 2SW-143B in Room 2040 and there are other manual valves in Rooms 2073 and 2094. As a backup, pump 2P-4C or 4B (depends on which one is operatmg) could be stopped and recovered aAer local isolation. Procedure -
220M22 provides direction to isolate based on low header pressure providing detection.
Also, auxiliary building semp alanns provide detection.
SpatialEfects: Propagation Effected Location: Room 2073
_ Spatial Effects Comments: Room 2073 casily prt==g*= down to Room 2040 through floor gratmg Also floor drams propagate to El 317. Room 2040 propagates to El 317 (Rooms 2006 & 2011) through floor drams and cast stairway. Room 2040 is a very large floor area, but eventually water could accumulate and fail MCC 2B52 if unisolated. An unisolated break would eventually fill El 317 and it is assumed that all ECCS equipment is flooded (propagation into rooms 2007, 2010, & 2014).
Initiating Event: N InitiatingEventID: LOSP Initiating Event Recovery: It is assumed that pipe break occurs during a LOSP accident demand which opens upstream valve 2CV-1504-2.
O Loss of System: N _
SystemIPEID: NA System Recovery: NA Loss of Train: T Train ID: SW Header #2 Train Recovery: SW header #2 is lost due to flow diversion until break is isolated. Isolation leads to loss I
of EDG and Control Room cooling train B.
Consequence Comments: Consequence is " Medium" based on Table 2-2: ' frequent frequency of m
challenge, between tests exposure, and I backup train (EDG and LOSP recovery). For the failure to isolate case, there is at least I backup (fail to i
isolate),
Consequence Category: MEDIUM o
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Page 113 Calculation No. NSD-023 Consequence ID: SW C-25A Consequence
Description:
Header #1 Supply to Fuel Pool HE During Operation in Room 2073 upstream of 2CV-1525-1 (2HBC-87-12)
Break Size: Large Isolability of Break: Yes ISO Comments: Stop pump 2P-4A or 4B (depends on which one is operating) and if aligned to ACW system, close either 2CV-1418-1 or 2CV-1419-1. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection. Also, auxiliary building sump alarms provide detection.
Spatial Effects:' Propagation Effected Location: Room 2073 Spatial Effects Comments: Propagation from Room 2073 to 2040 is relatively easy through gratmg Also, floor drains propagate to El 317. Room 2040 propagation is to El 317 (Rooms 2006 & 2011) through floor drains and east stairway. Room 2040 is a very large floor area, but eventually water could accumulate and fail MCC 2B52, if unisolated. He MCC fails Train A ECCS valves including CSS Valves 2CV-5612-1 and 2CV-5649-1 (Sump Recirculation A). An unisolated break would eventually fill El 317 and it is assumed that all ECCS equipment is flooded (propagation into rooms 2007,2010, & 2014).
Initiating Event: 1 Initiating Event ID: T8 Initiating Event Recovery: Loss of 2P-4A and service water header #1 unavailable and assumed not recovered in this analysis. It is also assumed that connected piping in standby qg (e.g., no flow) sees sufficient SW pressure to be challenged during normal operation.
Loss of System: S System IPE ID: NA System Recovery: CCW could be initially isolated per Procedure 2203.022, but could be recovered by the unaffected service water header. Also, if ACW is aligned, it would be isolated and could be recovered from the other unaffected header.
Loss of Train: T Train ID: SW Header #1 Train Recovery: See Initiating Event Recovery.
Consequence Comments: Consequence is ' Medium" based on Table 2-3 with 2 backup trams (EFW A, once through cooling, & possible PCS or AFW). For the failure to isolate case, there are 2 backup trams (failure to isolate, EFW A, & possible PCS or AFW)
Consequence Category: MEDIUM O
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Page 114 CalculationNo NSD-023 Consequence ID: SW C-25B Consequence
Description:
Hender #2 Supply to Fuel Pool HE During Operation in Room 2073 upstream of 2CV-1526-2 (2HBC-87-12)
J BreakSise: Large Isolability of Break: Yes ISO Comments: Stop pump 2P-4C or 4B (depends on which one is operatmg) and if aligned to ACW system, close either 2CV-1422-2 or 2CV-1421-2. Procedure 2203.022 provides direction to isolate based on low header pressure provuhng detection. Also, auxiliary building sump alarms provide detection.
Spatial ElTects: Propagation Effected Location: Room 2073 Spatial EfTects Comments: Propagation from Room 2073 to 2040 is relatively easy through gratmg Also, floor drams propagate to El 317. Room 2040 propagation is to El 317 (Rooms 2006 & 2011) through floor drams and east stairway. Room 2040 is a very large floor area, but eventually water could accumulate and fail MCC 2B52, if unisolated. The MCC fails Train A ECCS valves includmg CSS Valves 2CV-5612-1 and 2CV-5649-1 (Sump Recirculaten A). An unisolated break would eventually fill El 317 and it is manad that all ECCS equipment is flooded (propagation into rooms 2007,2010, & 2014).
Initiating Event: I Initiating Event ID: T9 Initiating Event Recovery: loss of 2P 4C and service water header #2 unavailable and assumed not recovered in this analysis. it is also assumed that c+=%i piping in standby (e.g., no flow) sees sufficient SW pressure to be challenged during normal operation.
Loss of System: S SystemIPEID: NA System Recovery: CCW could be initially isolated per Procedure 2203.022, but could be recovered by the unnKead service water header. Also, if ACW is aligned, it would be isolated and could be recovered from the other unaffected header.
Loss of Train: T TrainID: SWHeader#2 Train Recovery: See Initiating Event Recovery.
Consequence Comments: Consequence is " Medium" based on Table 2-3 with 2 backup trams (EFW B,
)
once through cooling, & possible PCS or AFW). For tiu: failure to isolate case, there are 2 backup trains (failure to isolate, EFW B, & possible PCS or AFW)
Consequence Category: MEDIUM i
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1 i
Page 115 Calculation No. NSD-023 Consequence ID: SW C-26 Consequence
Description:
Ceman_ Fuel Pool HE Piping Downstream of 2CV-1525-1 and 2CV-1526-2 During Operation in Room 2073 (2HBC-87-12 downstream of 2CV-1525-1 and 2CV-1526-2 and 2HBC-81-12 in Room 2073)
Creak Size: Large Isolability of Break: Yes ISO Comments:^ Close 2CV-1525-1 and/or 2CV-1526-2 (depending on which header is aligned).
Procedure 2203.022 provides direction to isolate based on low header pressure providing detection. Also, auxiliary building sump alarms provide detection.
Spatial Effects: Propagation Effected Location: Room 2073 Spatial Effects Comments: Propagation from Room 2073 to 2040 is relatively easy through gratmg Also, floor drains propagate to El 317. Room 2040 propagation is to El 317 (Rooms 2006 & 2011) through floor drains and east stauway. Room 2040 is a very large floor area, but eventually water could accumalate and fail MCC 2B52, if unisolated. De MCC fails Train A ECCS valves including CSS Valves 2CV-5612-1 and 2CV-5649-1 (Sump Recirculation A). An unisolated break would eventually fill El 317 and it is assumed that all ECCS equipment l
is flooded (popagation into rooms 2007,2010, & 2014).
l Initiating Event: I Initiating Event ID: T8 or T9 l-Initiating Event Recovery: Flow diversion occurs on the aligned service water header until isolated.
Loss of System: S SystemIPEID: FPC q
l System Recovery: Fuel pool cooling is lost, but there is signi6 cant time to recover beat removal or L
provide makeup to pool. His is judged to be a low consequence.
Loss of Train: T Train ID: SW Header #1 or #2 Train Recovery: See Initiating Event Recovery.
Consequence Comments: Failure to isolate consequence is " Medium" based on Table 2-3 with 2 backup trains (EFW A or B and isolation). Successful isolation is a " Low" consequence based on Table 2-1 with 3 backup trams (EFW, ECCS; an effective plant trip TI). Ioss of FPC is judged to be " Low" based on signficant time and makeup sources.
Consequence Category: MEDIUM O
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Page 116 Calculation No. NSD-023 Consequence ID: SW-C-27 Consequence
Description:
ACW Retun in Turbine Bldg During Operation (2JBD-618-12 in TAB upstream of check valve 2ACW-54 and 2JBD-618-8 and 6 in TAB)
Break Size: Large Isolability of Break: Yes ISO Comments: ACW can be isolated. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection. Also, tmbine building sump alarms provide detection.
SpatialEffects: Propagation Effected Location: TAB Spatial Effects Comments: Turbine auxiliary building propogates into turbine building with potential impacts on power conversion system and its support systems Initiating Event: I Initiating Event ID: T2 ort 8 or T9 Initiating Event Recovery: Potential flow diversion of ACW and impact on power conversion systsm assumed. Also, potential flow diversion from a service water header until isolated.
Loss of System: S SystemIPEID: PCS System Recovery: Loss of power conversion system (PCS) is assumed either due to floodmg or isolation.
Loss of Train: N Train ID:
Train Recovery: Potential loss of a service water header due to flow diversion until isolation.
Consequence Comments: Consequence is " Medium" based on Table 2-1 (T2 with isolation) and Medium with isolation failure based on Table 2-3.
Consequence Category: MEDIUM k
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Page 117 Calculation No. NSD-023 Consequence ID: SW C-28 Consequence
Description:
Not Used
' Break Size:
Isolability of Break:
ISO Comments:
Spatial Eficcts:
Effected Location:
Spatial Effects Comments:
k Initiating Event:
Initiating Event ID:
Initiating Event Recovery:
Loss of System:
System IPE ID:
System Recovery:
Loss of Train:
Train ID:
Train Recovery:
Consequence Comments:
Consequence Category:
l O
1 ano_swl. doc 3/26/98
Page 118 Calculation No. NSD-023 Consequence ID: SW-C-29 Consequence
Description:
Not Used Break Size:
Isolability of Break:
ISO Comments:
Spatial Effects:
Effected Location:
Spatial Efi'ects Comments:
Initiating Event:
Initiating Event ID:
Initiating Event Recovery:
Loss of System:
i., stem IPE ID:
System Recovery:
Loss of Train:
Train ID:
Train Recovery:
Consequence Comments:
Consequence Category:
ano_swl. doc 3/26/98
Page 119 Calculation No. NSD-023 Consequence ID: SW-C-30A
. Consequence
Description:
Header #1 Supply to EFW 2P7B in Room 2025 Upstream of MOV 2CV-0716-1 During Normal Operation (2HBC-85-6 Upstream of 2CV-0716-1 in Room 2025)
- Break Size: Large Isolability of Break: Yes ISO Comments: Stop pump 2P-4A or 4B (depends on which one is operating) and if aligned to ACW system, close either 2CV-1418-1 or 2CV-1419-1. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection. Also, auxiliary building sump alarms provide detection.
Spatial Effects: Propagation Effected Location: Room 2025 Spatial Effects Comments: EFW 2P7B will be flooded and unavailable. Propagation is into Room 2040 which propagates to El 317 (Rooms 2006 & 2011) through floor drains and cast stairway. Room 2040 is a very large floor area, but eventually water 1
could accumulate and fail MCC 2B52, if unisolated. 'Ihe MCC fails Train A ECCS valves including CSS Valves 2CV-5612-1 and 2CV-5649-1 (Sump Recirculation A). An unisolated break would eventually fill El 317 and it is assumed that all ECCS equipment is flooded (propagation into rooms 2007, 2010, & 2014).
Initiating Event: I Initiating Event ID: T8 Initiating Event Recovery: Ioss of 2P-4A and service water header #1 unavailable and assumed not recovered in this analysis. It is also assumed this v =M piping in standby (i.e., no flow) sees sufficient SW pressure to be challenged during normal operation.
Loss of System: S SystemIPEID: ACW System Recovery: CCW is partially isolated per Procedure 2203.022. Also, if ACW is aligned, it would be isolated and could be recovered from the other unaffected header and/or pumps. '
Loss of Train: TM-2 Train ID: SW Header #1 & EFW B Train Recovery: EFW B due to floodmg and SW header #1 due to flow diversion, then isolation. See Initiating Event Recovery.
Consequence Comments: Consequence is " Medium" based on Table 2-3 with 2 backup trains (EFW A, I train of once through cooling, & possibly PCS or AFW). For the failure to isolate case, there are 2 backup trains (failure to isolate, EFW A, & possibly PCS or AFW) l Consequence Category: MEDIUM O
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l Page 120 Calculation No. NSD-023 Consequence ID: SW-C-30B Consequence
Description:
Header #2 Supply to EFW 2P7A in Room 2024 Upstream of MOV 2CV-0711-2 During Normal Operation (2HBC-86-6 Upstream of 2CV-0711-2 in Room 2024)
BreakSize: Large Isolability of Bres&: Yes ISO Comments: Stop pump 2P-4C or 4B (depends on which one is operatmg) and if aligned to ACW system, close either 2CV-1422-2 or 2CV-1421-2. Procedure 2203.022 provides direction to isolate based on low header pressure providing detection. Also, auxiliary building sump alarms provide detection.
Spatial Effects: Propagation Effected Location: Room 2024 Spatial Effects Comments: EFW 2P7A will be flooded and unavailable. Propagation is into Room 2040 which propagates to El 317 (Rooms 2006 & 2011) through floor drams and east stairway. Room 2040 is a very large floor area, but eventually water could accumulate and fail MCC 2B52, if unisolated. The MCC fails Train A ECCS valves including CSS Valves 2CV-5612-1 and 2CV-5649-1 (Sump Recirculation A). An unisolated break would eventually fill El 317 and it is assumed that all ECCS equipment is flooded (propagation into rooms 2007, 2010, & 2014).
Initiating Event: I Initiating Event ID: T9 Initiating Event Recovery: Loss of 2P-4C and service water header #2 unavailable and assumed not recovered in this analysis. It is also assumed this c=W piping in standby (i.e., no flow) sees sufficient SW pressure to be challenged during normal operation.
Loss of System: S SystemIPEID: ACVv System Recovery: CCW is panially isolated per Procedure 2203.022. Also, if ACW is aligned, it would be isolated and could be recovered from the other unaffected header and/or pumps.
Loss of Train: TM-2 Train ID: SW Header #2 & EFW A Train Recovery: EFW A due to flooding and SW header #2 due to flow diversion, then isolation. See Initiating Event Recovery.
Consequence Comments: Consequence is " Medium" based on Table 2-3 with 2 backup trains (EFW B, I train of once through cooling, & possibly PCS or AFW). For the failure to isolate case, there are 2 backup trams (failure to isolate, EFW B, & possibly PCS or AFW)
Consequence Category: MEDIUM O
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4.
Page 121 Calculation No. NSD-023 1
Consequence ID: SW-C-31 Consequence
Description:
SWS Suction From Emergency Cooling Pond During Demand (2HBC-88 42 Outside)
Break Size: Large Isolability of Break: Yes 1
ISO Comments: The sluice gate MOVs can be reclosed.
Spatial ENects: Propagation Effected Location: Yard j
Spatial ENects Comments: None Initiating Event: N Initiating Event ID: Seismic Initiating Event Recovery: It is assumed that the the pipe breaks during the design basis seismic event demand which causes the loss of Lake Dardanelle.
Loss of System: M SystemIPEID: SWS System Recovery: SWS sluice gates can be closed, but the lake has also failed due to initiator.
Loss of Train: N TrainID; N Train Recovery: NA Consequence Comments: Consequence is "High" based on Table 2-2 with 0 backup trams (loss of all service water due to loss of ultimate heat sink)
Consequence Category: HIGH O
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Page 122 Calculation No. NSD-023 Consequence ID: SW-C-32 Consequence
Description:
SWS Return to Emergency Cooling Pond During Demand (2HBC-83-30 in TB, Yard)
Break Size: Large Isolability of Break: Yes ISO Comments: Reclosure of MOVs 2CV-1541-1 and 2CV-1560-2 will isolate the break, but this is not assumed since impact is in turbine building and outside.
i SpatialEffects: Propagation Effected Location: TB, Yard Spatial Effects Comments: Balance of plant systems in turbine building can be affected.
Initiating Event: N Initiating Event ID: LOCA Initiating Event Recovery: It is assumed that pipe break occurs during a LOCA accident de-ad Loss of System: N System IPE ID: N System Recovery: See ISO Comment above.
Loss of Train: N TrainID: N l
Train Recovery: NA l
Consequence Cmiimcr.t:: Consequence is " Low" based on Table 2-2 (unexpected frequency of demand and 2 backup trains - both service water trains)
Consequence Category: LOW
,O i
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