IR 05000413/1997004: Difference between revisions

From kanterella
Jump to navigation Jump to search
(StriderTol Bot insert)
 
(StriderTol Bot change)
 
Line 1: Line 1:
{{Adams
{{Adams
| number = ML20134P472
| number = ML20138J524
| issue date = 02/18/1997
| issue date = 01/31/1997
| title = Documents Closure of Apparent Violation Described in Insp Repts 50-413/97-04 & 50-414/97-04 Conducted on 970106-23 & Completes NRC Action in Subj Matter
| title = Insp Repts 50-413/97-04 & 50-414/97-04 on 970106-23.No Violations Noted.Major Areas Inspected:Operations & Engineering
| author name = Reyes L
| author name =  
| author affiliation = NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
| author affiliation = NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
| addressee name = Mccollum W
| addressee name =  
| addressee affiliation = DUKE POWER CO.
| addressee affiliation =  
| docket = 05000413, 05000414
| docket = 05000413, 05000414
| license number =  
| license number =  
| contact person =  
| contact person =  
| document report number = EA-97-036, EA-97-36, NUDOCS 9702250478
| document report number = 50-413-97-04, 50-413-97-4, 50-414-97-04, 50-414-97-4, NUDOCS 9702070324
| document type = CORRESPONDENCE-LETTERS, OUTGOING CORRESPONDENCE
| package number = ML20138J512
| page count = 6
| document type = INSPECTION REPORT, NRC-GENERATED, TEXT-INSPECTION & AUDIT & I&E CIRCULARS
| page count = 9
}}
}}


Line 18: Line 19:


=Text=
=Text=
{{#Wiki_filter:_ .
{{#Wiki_filter:,. .'
O February 18, 1997
U. S. NUCLEAR REGULATORY COMMISSION
~
EA 97-036 Duke Power Com]any ATTN: Mr. W. 1. McCollum Site Vice President Catawba Site


4800 Concord Road York. South Carolina 29745-9635 SUBJECT: EXERCISE OF ENFORCEMENT DISCRETION (NRC INSPECTION REPORT NOS. 50-413. 414/97-04)
==REGION II==
This letter refers to an inspection conducted during the period January 6 through 23, 1997, at your Catawba Nuclear Station. During the inspection, the 1 NRC examined the facts and circumstances surrounding your identification of a design deficiency associated with the Unit 1 and 2 Auxihary Feedwater (AFW)
Docket Nos: 50-413, 50-414 License Nos: NPF-35. NPF-52 Report Nos.: 50-413/97-04. 50-414/97-04 Licensee: Duke Power Company  l Facility: Catawba Nuclear Station. Units 1 and 2 Location: 422 South Church Street Charlotte. NC 28242  i Dates: January 6 - January 23. 1997 i
Syste On January 9, 1997, you submitted Licensee Event Report (LER)
Inspectors: R. J. Freudenberger. Senior Resident Inspector l P. A. Balmain. Resident Inspector  i R. L. Franovich. Resident Inspector  j Approved by: C. Casto. Chief Reactor Projects Branch 1 Division of Reactor Projects i
, No. 50-413/96-012 following the determination that the AFW system was outside '
    .
its design basis. Subsequently, on January 17, 1997. Revision 1 to the LER was submitted to provide additional information and corrective action Our review of this issue is discussed in detail in the subject inspection report
Enclosure 9702070324 970131 PDR 0 ADOCK 05000413 PDR
-
 
transmitted to you by letter dated January 31, 199 Based on the information develo)ed during the inspection, the NRC has determined that a violation of 1RC requirements occurred. Specifically, from
      !
'
,. .
EXECUTIVE SUMMARY Catawba Nuclear Station. Units 1 & 2 NRC Inspection Report 50-413/97-04. 50-414/97-04 This special inspection focused on the integrated efforts of the facility staff to evaluate, determine the root cause of, and correct a licensee-identified design deficiency involving the assured suction source (nuclear service water) to the auxiliary feedwater (AFW) pumps. The report covers the resident inspection period from January 6 to January 23. 199 Doeratiqn_g
. U)on discovery of a design deficiency that impacted the operability of t7e AFW systems, control room operators made appropriate notifications in the time periods required; appropriately implemented immediate actions in compliance with Technical Specifications (TS), and promptly developed ar4d executed short-term actions to restore trains of the AFW system to operable statu Enaineerina
. Appropriate compensatory actions were developed and implemented in a timely manner to restore the AFW system to operable but degraded status until a mcdification could be implemented to permanently correct the proble . The engineering support to develop the modification plan was responsive I to resolve the design deficiency. The plan was implemented in a timely manner. 6nd no concerns with the modification were identifie . The root cause evaluation provided in an initial Licensee Event Report I (LER 50-413/96-12) was not sufficiently developed to define the scope of similar potential design issues. The licensee's rationale for
      ,
l concluding that the root causes were different for the events documented l in LERs 50-413/96-04, 50-414/96-05, and 50-413/96-12 was not cogent and i did not drive long-term corrective actions to identify any additional l potential issues. A revised submitt61 of LER 50-413/96-12 proposed that '
the root cause investigation be continued; this corrective action was app priately scoped to ensure that similar potential design issues wou be revealed
. The design deficiency, which had existed since original construction and resulted in the AFW system being unable to perform its intended safety function under certain conditions, is characterized as Apparent Violation 50-413.414/97-04-0 ,
l i
l Enclosure l
l
      ,
 
,. .-
 
Reoort Details  .
i
      ,
I. Enaineerina l
E2 Engineering Support of Facilities and Equipment  l E2.1 Auxiliary Feedwater System Single Failure Design Deficiency
  ' Insoection Scoce (37551)
l On December 11, 1996, the licensee identified a design deficiency during- l a design review of assured makeup supply to the auxiliary feedwater j (AFW) system, The design review was conducted in support of a !
modification to reduce the ice condenser ice weight limit in Technical
      '
Specifications (TS). The inspector discussed the issue with plant :
3ersonnel: reviewed operability evaluations modification plans the !
Jpdated Final Safety Analysis Report (UFSAR) facility TS, LER 50-413.414/96-12 (Revisions 0 and 1), and station Problem Identification a Process (PIP) reports 0-C96-3241 and 0-C96-3266: evaluated the root :
cause investigation and proposed corrective actions: and observed ;
      '
portions of modifications implemented to correct the design oversigh Observations and Findinas
      '
Because they provide condensate quality water, the normal suction sources for auxiliary feedwater (AFW) are the AFW condensate storage ,
tank, upper surge tank, and condenser hotwell. However, these sources are not seismically qualified. Therefore, the' assured suction source for the AFW system (as described in FSAR Section 9.2.1) is nuclear ,
service water (NSW), which is seismically qualified but not of condensate quality. To ensure that a reliable source of water would be i available during a security event that would require operation of the '
standby shutdown system (SSS), the licensee incorporated a design that i would provide an additional suction source for the AFW pumps. Check '
valves were located in the suction piping to enable the additional suction source to feed all three AFW pumas, though only the turbine- 1 driven AFW pump was assumed to be availa]le during such a security even During a design review, the licensee determined that the flow of NSW !
(the assured supply) to the.AFW pumps was inadequate under certain -
accident scenarios. Specifically, with all three AFW pumps running with I high flow demand and loss of the normal suction sources, a single i
      '
failure of one of the two assured (NSW) makeup source valves (1(2)RN-250A or 1(2)RN-310B) would cause the remaining train of the assured source to attempt to supply all three AFW pumas. This would result in inadequate net positive suction head to all t1ree pumps, rendering them :
inoperabl The design deficiency involved the absence of check valves in locations j that would provide separation between the 'A' and 'B' trains of the ,
Enclosure ,.
r
  .
 
    . _ _ _ _ .
      ,
.
*
.
      [
      !
assured source suction to the AFW system. As indicated above, check '
valves were located upstream of a common header to the AFW pumps where train separation could not be achieve ;
The licensee promatly informed the NRC resident inspector of the design :
deficiency and su)mitted a 10 CFR 50.72 notification within the required i time period. At 11:15 a.m., on December 11. the licensee declared all ;
three AFW pumps on both units inoperable and entered TS action  .
3.7.1.2.c. which required them to immediately initiate corrective action !
to restore at least one AFW pump to o)erable status as soon as possibl l To restore two trains of AFW to operaale status, the licensee closed and i
      '
removed power from the Train B NSW supply valve (s) (1(2)CA-85B) to the turbine-driven AFW pump (s). This provided separation between the A and >
B Trains of AFW suction for both units, but also rendered the turbine- !
driven AFW pump (s) inoperable by elimir'ig one of the two assured !
suction sources. Consequently, this plE #1 both units in TS action i 3.7.1.2.a. which required restoration of the turbine-driven AFW pump (s) 1 to operable status within 72 hours. The inspector concluded that  i appropriate notifications were made in the time periods require ,
immediate actions to comply with TS were appropriately implemented, and
      '
short-term actions to provide train separation and restore the motor- >
driven AFW pumps were promptly developed and execute '
To restore the turbine-driven auxiliary feedwater pump (s) to operable !
status and maintain operability of the motor-driven AFW pumps, the !
licensee o)ened the assured source suction valves (1(2)RN-250A and 1(2)RN-3103) and then removed power to ensure that their open position was maintained. In addition. the NSW system was aligned to its assured :
source (i.e.. the standby nuclear service water pond). This ensured l that all other related credible single failures on the NSW system would i not prevent the AFW system from performing its intended safety functio t
      '
The licensee performed an operability evaluation to demonstrate that the Unit 1 and Unit 2 AFW systems were operable but degraded in this  ;
configuration. The inspector concluded that this action was appropriate to ensure system operability until a modification could be implemented to permanently correct the problem. The operability evaluation supported the action and adequately demonstrated the operability of the system in a degraded conditio A modification plan was developed by the engineering organization to install check valves in appropriate locations of the AFW system. The modification for Unit 2 was completed during a forced shutdown (to correct a nitrogen entrainment condition in the 2B residual heat removal pump and discharge piping) from December 16. to December 20. 1996: the modification for Unit 1 was completed on January 9.1997. The inspector concluded that the engineering support to develop the modification plan was responsive in resolving the design deficiency and implemented in a timely manner. No concerns with the modification were identifie ~he design deficiency was documented in Licensee Event Report (LER)
00-413/96-12. which was superseded by a subsequent revision. The original LER. submitted on January 9.1997, stated that the root cause Enclosure
 
, . _ _ . _ _ _ _ _ _  _ _ _ _ _ _ _ _ _ _ _ _ . _ . _ . _ .
  -
,. .
 
was suspected to be an initial design oversight. The LER also referred  l to two previous events involving design issues associated with the Standby Shutdown System (SSS): these events are documented in LERs 50-413/96-04 and 504414/96-05. The licensee asserted in LER 50-413/96-12  ;
that the root causes associated with the referenced LERs and LER 50-  l 413/96-12 were different to support a conclusion that the event documented in LER 50-413/96-12 was nonrecurrin No long-term l corrective actions'were defined. The inspector determined that the root  :
cause evaluation was not sufficiently developed to define the scope of :
similar potential design issues. In addition. the licensee's rationale  i for concluding that the root causes of the events documented in LERs 50-413/96-04, 50-414/96-05, and 50-413/96-12 were different was not cogent  ;
and did not drive long-term corrective actions to identify any  ;
additional potential issues. The inspector discussed these observations  i with the license i Revision 1 to LER 50-413/96-12. submitted on January 17. elaborated on  l the root cause. The revised LER established that common contributing
        '
factors existed between itself and the two events documented in LERs 50- '
l  413/96-04 and 50-414/96-05. The difficulty was encountered in the l  verification of information from original design sources immediately  .
;
available. The licensee concluded that a broader investigation and  ,
l  corrective actions.to ensure that no further problems exist was warranted. The inspector determined that the proposed continuation of
'
'
initial construction of Units 1 and 2 until December 11. 1996, measures were not established to correctly translate the design basis of the AFW system .
the root cause investigation was appro)riately scoped to ensure that similar potential design issues would ]e reveale ,
described in the Final Safety Analysis Report. Section 9.2.1 into specifications, drawings, and procedures for the Nuclear Service Water (NSW)
        ,
System (the assured water source for the AFW system) resulting in the
The revised LER also delineated long-term corrective actions to:
  ,
  (1) conduct an investigation into the sequence of changes since the original design of the AFW system to ensure that the root cause investigation is appropriately scoped for corrective actions to be  ,
requirements of Technical Specification (TS) 3.7.2.1 not being met for both units. Because the AFW systems' assured source lacked adequate train separation, a single, active failure of one of the two assured source suction valves (1/2RN-250 or 1/2RN-310) would render all three AFW pumps for the associated unit inoperable under certain condition Specifically, with all three AFW pumps running with high flow demand ar,a a loss of the normal suction sources (non-safety related), a single failure of one of the two assured source suction valves would cause the remaining train of the assured source to attempt to supply all three AFW pumps. This would result in inadequate net positive suction head to all three pumps, rendering them inoperabl In accordance with the " General Statement of Policy and Procedures for Enforcement Actions" (Enforcement Policy). NUREG-1600. this violation normally would be categorized as a Severity Level III violation. However, as discussed in Section VII.B.3 of the Enforcement Policy. the NRC may refrain from issuing a Notice of Violation (Notice) and proposing a civil Jenalty for a Severity Level III violation that involves a past problem, suc1 as an old engineerin design, or installation deficiency, provided that certain criteria are me OFFICIAL COPY
effectively determined: (2) conduct a reconstitution of the electrical l  and mechanical system design basis for the SSS interfacing systems; and .
  .nn PDR ADOCK 05000413 G  PDR
  (3) conduct a review of the Operating Experience Database for SSS interfacing systems to identify any other adverse trends. The inspector ;
concluded that the planned corrective actions delineated in the revised ;
LER were sufficiently thorough to identify potential weaknesses in i previous design reviews associated with the addition of SSS interface '
c. Conclusions    .
l The failure to correctly translate the design described in FSAR Section 9.2.1 resulted in a violation of 10 CFR 50. Appendix B. Criterion III  i (Design Control) and TS 3.7.1.2. However, the licensee identified the i
        ^
design deficiency, took effective immediate and short-term corrective actions and has planned comprehensive long-term corrective action This licensee identified and corrected violation is characterized as  >
l  Apparent Violation (EEI) 50-413.414/97-04-01: AFW System Single Failure i  Design Deficiency. Unresolved Item (URI) 50-413.414/96-20-02:  .
'
Auxiliary Feedwater Assured Source Single Failure Design Deficiency, is closed.
 
l
        <
Enclosure ,
i
    -  - - , ..
 
-
.-
 
II. Manaaement Meetinas X1 Exit Meeting Summary The inspectors ) resented the inspection results to members of licensee management at t1e conclusion of the inspection on January 23. 1997. The licensee acknowledged the findings presented. No proprietary information was identi fie l
      .
 
Enclosure


_ _ _ _ _ ..
  *
  *
  .
  .
d DPC  -2-After review of this violation and consultation with the Director, Office of Enforcement the NRC has concluded that the criteria for enforcement
..
, discretion have been met. Therefore, to encourage licensee efforts to identify and correct subtle violations before degraded safety systems are called upon to function, no Notice is being issued in this case. The specific bases for this decision are: (1) you identified the violation during a
, licensee-initiated design review conducted in support of a modification:
(2) although voluntary self-initiated technical audits had beer 1 performed for both the AFW =and NSW systems, it was not unreasonable tha' these audits did not identify the deficiency earlier, and it is unlikely the deficiency would
'
have been identified by routine surveillances or quality a surance audits:
(3) timely and appropriate modifications were completed to mstall check valves in locations to resolve the deficiency: (4) timely and effective corrective actions were implemented, and appropriate long-term corrective actions to review and identify any similar design deficiencies in the systems interfacing with the Standby Shutdown System were delineated; and (5) the design deficiency occurred at the time of plant construction and is not reasonably linked to present engineering performanc This letter serves to document the closure of the ap)arent violation (eel 50-413 and 50-414/97-04-01) described in the su) ject inspection re) ort and completes the NRC's action in this matter. No formal response to t1is letter is required. In accordance with 10 CFR 2.790 of the NRC's " Rules of Practice," a copy of this letter will be placed in the NRC Public Document Roo If you should have any questions regarding this letter, please contact Mr. Charles Casto. Chief Branch 1. Division of Reactor Projects, at 404-331-550 Sincer ly, ,
    .
Luis A. Reyes Regional Admin &s rator Docket Nos. 50-413, 50-414 License Nos. NPF-35, NPF-52 cc:
M. S. Kitlan Regulatory Compliance Manager Duke Power Company 4800 Concord Road York. SC 29745-9635 cc: (Cont'd on Page 3)


  .._ _ _ . .. __ _ _ . I
Partial List of Persons Contacted Licensee Bhatnager A., Operations Superintendent Coy, S., Radiation Protection Manager Forbes, J., Engineering Manager Harrall. T., IAE Maintenance Superintendent Kelly C., Maintenance Manager Kimball. D., Safety Review Group Manager Kitlan M., Regulatory Compliance Manager McCollum, W., Catawba Site Vice-President Peterson, G., Station Manager Tower. D.. Compliance Engineer
    \
      .
.
I l
DPC  -3-
      .
    ,
Enclosure
cc (Cont'd):    j Paul R. Newton Legal Department (PB05E)
Duke Power Company 422 South Church Street Charlotte, NC 28242-0001 Robert P. Gruber Executive Director Public Staff - NCUC P. O. Box 29520 Raleigh. NC 27626-0520 J. Michael McGarry, III. Es .
Winston and Strawn  I 1400 L Street. NW Washington D. C. 20005 North Carolina MPA-1  ,
Suite 600    -
P. O. Box 29513 Raleigh. NC 27626-0513  l Max Batavia, Chief
    !
Bureau of Radi.ological Health S. C. Department of Health  .
and Environmental Control 2600 Bull Street Columbia, SC 29201 Richard P. Wilson. Es Assistant Attorney General S. C. Attorney General's Office  ;
P. O. Box 11549  i Columbia. SC 29211 i
Michael Hirsch Federal Emergency Management Agency  ,
    ,
500 C Street. Sw. Room 840  '
Washington, D. C. 20472 cc: (Cont'd on Page 4)
.
e t


  .. - . . _ . ... _- -.- - . - - - - . -
  . .. - . . - .
    ,
  '
4 4    T DPC  -4-
. cc (Cont'd):    i North Carolina Electric  '
.~
Membership Corporation P. O. Box 27306 Raleigh NC 27611 Karen E. Long Assistant Attorney General N. C. Department of Justice  i P. O. Box 629    :
Raleigh. NC 27602  !
Saluda River Electric Cooperative. In ,
P. O. Box 929    !
Laurens. SC 29360 Peter R. Harden IV Account Sales Manager Power Systems Field Sales Westinghouse Electric Corporation P. O. Box 7288 C.larlotte. NC 28241 County Manager of York County York County Courthouse York. SC 29745 Piedmont Municipal Power Agency 121 Village Drive Greer. SC 29651 G. A. Copp Licensing - EC050 Duke Power Company P. O. Box 1006 Charlotte. NC 28201-1006 T. Richard Puryear Owners Group North Carolina Electric Membership Corporation 4800 Concord Road York. SC 29745 4 . - . . - - - .. _ .-.
~
  .
Duke Power Company-5-Distribution:
PUBLIC HT.hompson, EDO EJordan DEDO    .-
' GTracy ,OEDO LReyes,,RII LChandler OGC
,
,
Inspection Procedure Used IP 37551: Onsite Engineering Items Oh.ned Doened 50-413.414/97-04-01 EEI Auxiliary Feedwater System Single Failure Design Deficiency Closed 50-413.414,96-20-02 URI Auxiliary Feedwater Assured Source Single Failure Design Deficiency Discussed 50-413/96-12 (Rev.1) LER Auxiliary Feedwater System Found Outside Design Basis l
l l
l l
l
i
      !
Enclosure i
.. . - - - - . . .
*
. .
.
LIST OF ACRONYMS USED
!
!
JGoldberg, OGC RZimmerman,, NRR EJplian, SECY 8 Keeling CA Enforceme,nt Coordinators  l RI, RIII RIV    1 JLieberman,, DE j
l l AFW -
DE:EA RP dersen, File OE(BSummers) (2 letterhead)
Auxiliary Feedwater System Code of Federal Regulations
EH den, OPA l GC puto, 01 DR ss, AEOD    -
;
HB 11, DIG i
HB rkow, NRR PT9m,NRR
,
CEyans, RII Buryc, RII KClark,RII    '
RTrojanowski,Ril    I JJdhnson RII    i JJqudon,,Rll RCarroll, RII CCg'sto,Rll ABoland, RII    i NRCResidentInipector
,
U.S. Nuclear Regulatory Commission  '
L i 4830 Concord Rodd York,i SC 29745 l
l of, . 1 (
i OE R!d RA:RI!k  D:N RPedersen LReyes #,d  ;
JLNerman '
02/l$/97 02/)k/97
    ;
02/d/97 l t
Doc Name: G:\0ECASES\97036REV.RP
'
'
i i
CFR -
l i
DPC -
l
Duke Pwer Company EEI -
Escalated Enforcement Item (Apparent Violation)
FSAR - Final Safety Analysis Report IR -


FROM    g;,3g,3997 34 20  P. 1
==Inspection Report==
,.**
LER -
_
Licensee Event Report NSW -
Nuclear Service Water PIP -
Problem Investigation Process SSS -
Standby Shutdown System TS -
Technical Specifications UFSAR - Updated Final Safety Analysis Report URI -
Unresolved Item VIO -
Violation
     .
     .
AD Duke Power Company  -5-  i
Enclosure
)fstribution:
SUBLIC    !
      '
>
HThompson, E00
      ! '
EJordan DEDO    i GTracy, OEDO LReyes,RII    1 LChandler OGC JGoldberg,, OGC RZimmerman, NRR EJulian, SECY BKeeling CA Enforceme,nt Coordinators    !
RI, RIII RIV    1 JLieberman,, OE
      {
OE:EA RP dersen,File OE(BSummers) (2 lotterhead)  <
EH den, OPA GC puto, O!    {
      >
DR.ss, AE00    I HB911, O!G HB9rkow, NRR PT4m, NRR CEtans,RII Buryc, RII KClark, RII RTrojanowski,Ri!    I
      '
JJdhnson RII JJaudon,,Rll RCarroll RII (
CCqsto,kil ABoland, RII    ,
NRC Resident Inspector    I
      '
U.S. Nuclear Regulatory Commission 4830 Concord Road York, SC 29745    ,
 
I 4'
  -
    \
OE Rtd RA:RI!  0:N RPederson LReyes #,d JLINerman 02/1997 02/l d 797 02Ni/97 Doc Name: 6:\0ECASES\97036REV.RP l
      '
i
  . _ _ _ -
}}
}}

Latest revision as of 16:48, 29 June 2020

Insp Repts 50-413/97-04 & 50-414/97-04 on 970106-23.No Violations Noted.Major Areas Inspected:Operations & Engineering
ML20138J524
Person / Time
Site: Catawba  Duke Energy icon.png
Issue date: 01/31/1997
From:
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
To:
Shared Package
ML20138J512 List:
References
50-413-97-04, 50-413-97-4, 50-414-97-04, 50-414-97-4, NUDOCS 9702070324
Download: ML20138J524 (9)
v • d • e


Text

,. .'

U. S. NUCLEAR REGULATORY COMMISSION

REGION II

Docket Nos: 50-413, 50-414 License Nos: NPF-35. NPF-52 Report Nos.: 50-413/97-04. 50-414/97-04 Licensee: Duke Power Company l Facility: Catawba Nuclear Station. Units 1 and 2 Location: 422 South Church Street Charlotte. NC 28242 i Dates: January 6 - January 23. 1997 i

Inspectors: R. J. Freudenberger. Senior Resident Inspector l P. A. Balmain. Resident Inspector i R. L. Franovich. Resident Inspector j Approved by: C. Casto. Chief Reactor Projects Branch 1 Division of Reactor Projects i

.

Enclosure 9702070324 970131 PDR 0 ADOCK 05000413 PDR

!

'

,. .

EXECUTIVE SUMMARY Catawba Nuclear Station. Units 1 & 2 NRC Inspection Report 50-413/97-04. 50-414/97-04 This special inspection focused on the integrated efforts of the facility staff to evaluate, determine the root cause of, and correct a licensee-identified design deficiency involving the assured suction source (nuclear service water) to the auxiliary feedwater (AFW) pumps. The report covers the resident inspection period from January 6 to January 23. 199 Doeratiqn_g

. U)on discovery of a design deficiency that impacted the operability of t7e AFW systems, control room operators made appropriate notifications in the time periods required; appropriately implemented immediate actions in compliance with Technical Specifications (TS), and promptly developed ar4d executed short-term actions to restore trains of the AFW system to operable statu Enaineerina

. Appropriate compensatory actions were developed and implemented in a timely manner to restore the AFW system to operable but degraded status until a mcdification could be implemented to permanently correct the proble . The engineering support to develop the modification plan was responsive I to resolve the design deficiency. The plan was implemented in a timely manner. 6nd no concerns with the modification were identifie . The root cause evaluation provided in an initial Licensee Event Report I (LER 50-413/96-12) was not sufficiently developed to define the scope of similar potential design issues. The licensee's rationale for

,

l concluding that the root causes were different for the events documented l in LERs 50-413/96-04, 50-414/96-05, and 50-413/96-12 was not cogent and i did not drive long-term corrective actions to identify any additional l potential issues. A revised submitt61 of LER 50-413/96-12 proposed that '

the root cause investigation be continued; this corrective action was app priately scoped to ensure that similar potential design issues wou be revealed

. The design deficiency, which had existed since original construction and resulted in the AFW system being unable to perform its intended safety function under certain conditions, is characterized as Apparent Violation 50-413.414/97-04-0 ,

l i

l Enclosure l

l

,

,. .-

Reoort Details .

i

,

I. Enaineerina l

E2 Engineering Support of Facilities and Equipment l E2.1 Auxiliary Feedwater System Single Failure Design Deficiency

' Insoection Scoce (37551)

l On December 11, 1996, the licensee identified a design deficiency during- l a design review of assured makeup supply to the auxiliary feedwater j (AFW) system, The design review was conducted in support of a !

modification to reduce the ice condenser ice weight limit in Technical

'

Specifications (TS). The inspector discussed the issue with plant :

3ersonnel: reviewed operability evaluations modification plans the !

Jpdated Final Safety Analysis Report (UFSAR) facility TS, LER 50-413.414/96-12 (Revisions 0 and 1), and station Problem Identification a Process (PIP) reports 0-C96-3241 and 0-C96-3266: evaluated the root :

cause investigation and proposed corrective actions: and observed ;

'

portions of modifications implemented to correct the design oversigh Observations and Findinas

'

Because they provide condensate quality water, the normal suction sources for auxiliary feedwater (AFW) are the AFW condensate storage ,

tank, upper surge tank, and condenser hotwell. However, these sources are not seismically qualified. Therefore, the' assured suction source for the AFW system (as described in FSAR Section 9.2.1) is nuclear ,

service water (NSW), which is seismically qualified but not of condensate quality. To ensure that a reliable source of water would be i available during a security event that would require operation of the '

standby shutdown system (SSS), the licensee incorporated a design that i would provide an additional suction source for the AFW pumps. Check '

valves were located in the suction piping to enable the additional suction source to feed all three AFW pumas, though only the turbine- 1 driven AFW pump was assumed to be availa]le during such a security even During a design review, the licensee determined that the flow of NSW !

(the assured supply) to the.AFW pumps was inadequate under certain -

accident scenarios. Specifically, with all three AFW pumps running with I high flow demand and loss of the normal suction sources, a single i

'

failure of one of the two assured (NSW) makeup source valves (1(2)RN-250A or 1(2)RN-310B) would cause the remaining train of the assured source to attempt to supply all three AFW pumas. This would result in inadequate net positive suction head to all t1ree pumps, rendering them :

inoperabl The design deficiency involved the absence of check valves in locations j that would provide separation between the 'A' and 'B' trains of the ,

Enclosure ,.

r

.

. _ _ _ _ .

,

.

.

[

!

assured source suction to the AFW system. As indicated above, check '

valves were located upstream of a common header to the AFW pumps where train separation could not be achieve ;

The licensee promatly informed the NRC resident inspector of the design :

deficiency and su)mitted a 10 CFR 50.72 notification within the required i time period. At 11:15 a.m., on December 11. the licensee declared all ;

three AFW pumps on both units inoperable and entered TS action .

3.7.1.2.c. which required them to immediately initiate corrective action !

to restore at least one AFW pump to o)erable status as soon as possibl l To restore two trains of AFW to operaale status, the licensee closed and i

'

removed power from the Train B NSW supply valve (s) (1(2)CA-85B) to the turbine-driven AFW pump (s). This provided separation between the A and >

B Trains of AFW suction for both units, but also rendered the turbine- !

driven AFW pump (s) inoperable by elimir'ig one of the two assured !

suction sources. Consequently, this plE #1 both units in TS action i 3.7.1.2.a. which required restoration of the turbine-driven AFW pump (s) 1 to operable status within 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />. The inspector concluded that i appropriate notifications were made in the time periods require ,

immediate actions to comply with TS were appropriately implemented, and

'

short-term actions to provide train separation and restore the motor- >

driven AFW pumps were promptly developed and execute '

To restore the turbine-driven auxiliary feedwater pump (s) to operable !

status and maintain operability of the motor-driven AFW pumps, the !

licensee o)ened the assured source suction valves (1(2)RN-250A and 1(2)RN-3103) and then removed power to ensure that their open position was maintained. In addition. the NSW system was aligned to its assured :

source (i.e.. the standby nuclear service water pond). This ensured l that all other related credible single failures on the NSW system would i not prevent the AFW system from performing its intended safety functio t

'

The licensee performed an operability evaluation to demonstrate that the Unit 1 and Unit 2 AFW systems were operable but degraded in this  ;

configuration. The inspector concluded that this action was appropriate to ensure system operability until a modification could be implemented to permanently correct the problem. The operability evaluation supported the action and adequately demonstrated the operability of the system in a degraded conditio A modification plan was developed by the engineering organization to install check valves in appropriate locations of the AFW system. The modification for Unit 2 was completed during a forced shutdown (to correct a nitrogen entrainment condition in the 2B residual heat removal pump and discharge piping) from December 16. to December 20. 1996: the modification for Unit 1 was completed on January 9.1997. The inspector concluded that the engineering support to develop the modification plan was responsive in resolving the design deficiency and implemented in a timely manner. No concerns with the modification were identifie ~he design deficiency was documented in Licensee Event Report (LER)

00-413/96-12. which was superseded by a subsequent revision. The original LER. submitted on January 9.1997, stated that the root cause Enclosure

, . _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ . _ . _ .

-

,. .

was suspected to be an initial design oversight. The LER also referred l to two previous events involving design issues associated with the Standby Shutdown System (SSS): these events are documented in LERs 50-413/96-04 and 504414/96-05. The licensee asserted in LER 50-413/96-12  ;

that the root causes associated with the referenced LERs and LER 50- l 413/96-12 were different to support a conclusion that the event documented in LER 50-413/96-12 was nonrecurrin No long-term l corrective actions'were defined. The inspector determined that the root  :

cause evaluation was not sufficiently developed to define the scope of  :

similar potential design issues. In addition. the licensee's rationale i for concluding that the root causes of the events documented in LERs 50-413/96-04, 50-414/96-05, and 50-413/96-12 were different was not cogent  ;

and did not drive long-term corrective actions to identify any  ;

additional potential issues. The inspector discussed these observations i with the license i Revision 1 to LER 50-413/96-12. submitted on January 17. elaborated on l the root cause. The revised LER established that common contributing

'

factors existed between itself and the two events documented in LERs 50- '

l 413/96-04 and 50-414/96-05. The difficulty was encountered in the l verification of information from original design sources immediately .

available. The licensee concluded that a broader investigation and ,

l corrective actions.to ensure that no further problems exist was warranted. The inspector determined that the proposed continuation of

'

the root cause investigation was appro)riately scoped to ensure that similar potential design issues would ]e reveale ,

,

The revised LER also delineated long-term corrective actions to:

(1) conduct an investigation into the sequence of changes since the original design of the AFW system to ensure that the root cause investigation is appropriately scoped for corrective actions to be ,

effectively determined: (2) conduct a reconstitution of the electrical l and mechanical system design basis for the SSS interfacing systems; and .

(3) conduct a review of the Operating Experience Database for SSS interfacing systems to identify any other adverse trends. The inspector ;

concluded that the planned corrective actions delineated in the revised ;

LER were sufficiently thorough to identify potential weaknesses in i previous design reviews associated with the addition of SSS interface '

c. Conclusions .

l The failure to correctly translate the design described in FSAR Section 9.2.1 resulted in a violation of 10 CFR 50. Appendix B. Criterion III i (Design Control) and TS 3.7.1.2. However, the licensee identified the i

^

design deficiency, took effective immediate and short-term corrective actions and has planned comprehensive long-term corrective action This licensee identified and corrected violation is characterized as >

l Apparent Violation (EEI) 50-413.414/97-04-01: AFW System Single Failure i Design Deficiency. Unresolved Item (URI) 50-413.414/96-20-02: .

'

Auxiliary Feedwater Assured Source Single Failure Design Deficiency, is closed.

l

<

Enclosure ,

i

- - - , ..

-

.-

II. Manaaement Meetinas X1 Exit Meeting Summary The inspectors ) resented the inspection results to members of licensee management at t1e conclusion of the inspection on January 23. 1997. The licensee acknowledged the findings presented. No proprietary information was identi fie l

.

Enclosure

.

..

Partial List of Persons Contacted Licensee Bhatnager A., Operations Superintendent Coy, S., Radiation Protection Manager Forbes, J., Engineering Manager Harrall. T., IAE Maintenance Superintendent Kelly C., Maintenance Manager Kimball. D., Safety Review Group Manager Kitlan M., Regulatory Compliance Manager McCollum, W., Catawba Site Vice-President Peterson, G., Station Manager Tower. D.. Compliance Engineer

.

I l

.

Enclosure

. .. - . . - .

'

,

Inspection Procedure Used IP 37551: Onsite Engineering Items Oh.ned Doened 50-413.414/97-04-01 EEI Auxiliary Feedwater System Single Failure Design Deficiency Closed 50-413.414,96-20-02 URI Auxiliary Feedwater Assured Source Single Failure Design Deficiency Discussed 50-413/96-12 (Rev.1) LER Auxiliary Feedwater System Found Outside Design Basis l

l l

l l

l

i

!

Enclosure i

.. . - - - - . . .

. .

.

LIST OF ACRONYMS USED

!

l l AFW -

Auxiliary Feedwater System Code of Federal Regulations

'

CFR -

DPC -

Duke Pwer Company EEI -

Escalated Enforcement Item (Apparent Violation)

FSAR - Final Safety Analysis Report IR -

Inspection Report

LER -

Licensee Event Report NSW -

Nuclear Service Water PIP -

Problem Investigation Process SSS -

Standby Shutdown System TS -

Technical Specifications UFSAR - Updated Final Safety Analysis Report URI -

Unresolved Item VIO -

Violation

.

Enclosure

Retrieved from "https://kanterella.com/w/index.php?title=IR_05000413/1997004&oldid=2866261"