05000423/LER-1996-015, :on 960610,noncompliance W/Electrical Separation Requirements for Redundant Protection Trains, Occurred.Caused by Inadequate Job Skills for Maintaining Electrical Separation.Procedures Have Been Revised: Difference between revisions

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{{Adams
#REDIRECT [[05000423/LER-1996-015]]
| number = ML20198T272
| issue date = 11/05/1997
| title = :on 960610,noncompliance W/Electrical Separation Requirements for Redundant Protection Trains, Occurred.Caused by Inadequate Job Skills for Maintaining Electrical Separation.Procedures Have Been Revised
| author name = Smith D
| author affiliation = NORTHEAST NUCLEAR ENERGY CO.
| addressee name =
| addressee affiliation =
| docket = 05000423
| license number =
| contact person =
| document report number = LER-96-015, LER-96-15, NUDOCS 9711140246
| package number = ML20198T267
| document type = LICENSEE EVENT REPORT (SEE ALSO AO RO), TEXT-SAFETY REPORT
| page count = 7
}}
{{LER
| Title = :on 960610,noncompliance W/Electrical Separation Requirements for Redundant Protection Trains, Occurred.Caused by Inadequate Job Skills for Maintaining Electrical Separation.Procedures Have Been Revised
| Plant =
| Reporting criterion = 10 CFR 50.73(a)(2)(x), 10 CFR 50.73(a)(2)(ii)(B), 10 CFR 50.73(a)(2)(vii), 10 CFR 50.73(a)(2)(v), 10 CFR 50.73(a)(2)
| Power level =
| Mode =
| Docket = 05000423
| LER year = 1996
| LER number = 15
| LER revision = 0
| Event date =
| Report date =
| ENS =
| abstract =
}}
 
=text=
{{#Wiki_filter:-
~.
.=.--
NRC FORM 366 U.S. NUCLEAR REGULATORY Commission APPROVED BY OMS No. 31f,o4104 ExPents 04t30/98 M 951 Eo"a iEr oIEoUeE[icEaTo"d[sNoNs sNa'rt"o $$M tu;"%'%5,17"*!!!#.3 'c"sM/0?.'"WJ,2 ^=
UCENSEE EVENT REPORT (LER)
Wu'"J '=caat/ea ut;'g $ ",^pa~,,,' t"gc a
bun??bAu'el33': ',*2lILY3"oWfuts'"'**'-
ISee reverse for required number Of digits /charactersfor each block)
FiCarrY NAME (1)
DOCKET NUMBER (29 PAGE(3)
Millstone Nuclear Power Station Unit 3 05000423 1 of 7 TITLt 14)
Inadequate Electrical Separation Between Redundant Protection Trains Associated with Reactor Trip Swliches and Reactor Trip Breaker Indicating Lights EVENT DATE (5)
LER NUMBER (6)
REPORT DATE (7) 0,THER FACILITIES INVOLVED (8)
MONTH DAY YEAR YEAR sEoVENTIAL REVislON MONTH DAY YEAR FAC!uTV NAME DOCKET NUM8ER NUMBER NUMBER 05 11 05 97 06
?O 96 96 015 OPERATING 5
THis REPORT is SUBMITTED PURSUANT TO THE REQUIREMENTS oF lo CFR 1: (Check one of f.iore) (11)
MODE (9) 20.2201(b) 20.2203(aH2)(v) 50.73(aH2)(i) 50.73(aH2)(viii)
POWER 000 20.2203(e)(1) 20.2203(aH3Hil X' 50.73(an2Hii) 50.73(a)(2)(x)
LEVEL (10) 20.2203(aH2)(il 20.2203(aH3Hid 60.73(a)(2Hiid 73.71 20.2203(aH2)(i0 20.2203(a)(4) 50.73laH2)(iv) oTHER L
~
~
20.2203(aH2Hiid 60.36(cH1)
X So.73(aH2Hv) co. city in Abstract b.iow
~
20.2203(aH2)(ev) 50.36(cH2)
X 50.73(aH2Hvii)
LICENSEE CONTACT FoR THis LER (12) 5AME TELEPHONE NUMBER liricaude Area Codel David A, Smith, MP3 Nuclear Licensing Manager (860)437 5840 COMPLETE ONE LINE FOR EACH COMPONENT FAILURE DESCRIBED IN THIS REPORT (13)
~
l
 
==CAUSE==
SYSTEM COMPONENT l MANUF ACTURER REPORI ABLE
 
==CAUSE==
SYSTEM COMPONENT MANUFACTURER RE PORT ABLE TO NPRDS TO NPROS i
SUPPLEMENTAL REPORT EXPECTED (14)
EXPECTED MONTH DAY YEAR l
YEs X NO suBMtssioN DATE (16)
(If yes, comptate EXPECTED sVBMissioN DATE).
ABSTRACT (Lemrt to 1400 spaces,1.e., approxenately 15 single-spaced typewrittenlines) (16)
On June 10,1996, with the plant in Mode 5, it was determined that e noncompliance with electrical separation requirements for redundant protection trains had occurred and this was a condition outside the design basis of the plant. Additional electrical separation noncompliances were reported in August, September, and November 1996, and in February and April 1997 supplements to this report This supplement reports electrical separation noncompliances determined reportable on October 9,1997, pursuant to 10CFR50.73(a)(2)(ii)(B) as conditions outside the design basis of the plant.
Based on the number of electrical separation noncompliances in the March and April 1997 inspections, the failure to comply with electrical separation criteria appears to have been mainly an electrical installation problem that existed prior to ir.itial plant startup. However, some of these instances were apparently caused during maintenance and modifications after startup. The October 1997 identified instances of electrical separation noncompliance are considered to be isolated occurrences.
l There were no adverse safety consequences from this cond tion, in that the unit has not experienced an event as a L
result of a failure in electrical separation, however, this condition is significant t' ise these conditions are outside the design basis.
l Completed corrective actions include intemal electrical panelinspections, rt, : sons to work planning process
, procedures, and personnel training on electrical separation. Correction of identified electrical separation noncompliances will be completed prior to entry into Mode 4.
9711140246 971105 PDR ADOCK 05000423 8
PDR
 
4 N~.C FoMM 366A U.S. NUCLEAR REoVLAToRY CoMMISSloN LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION
'~F AclLITY NAME'11)
DOCKET NUMBER (2)
LER NUM8ER {6)
PAoE (3)
YEAR SEQUENTIAL REVislON Millstone Nuclear Power Station Unit 3 05000423 NUMBER NUMBER 2 of 7 015 05 96 TEK1 tilrnore space is required. use edditionalcopies of NRC form 366A) (17) l.
 
==Description of Event==
On June 10,1996, at 15:30 hours, with the plant in Mude 5 at 0-percent power, it was determined that a noncompliance with electrical separation requirements for redundant protection trains was a condition outside the design basis of the plint. A single electrical fault could potentially hue rendered the manual Reactor Trip Switch on the main control board Inoperable for both A and D Trains. As a result the Reactor Trip Switch on the main control board was dec.lared inoperable and an immediate notification was made on June 10,1996, pursuant to 10CFR50.72(b)(1)(ii)(B) as a condition outside the design basis of the plant.
In August 1996, during electrical separation inspections additional noncompliances (descrit'ed below) were identified in sections of the main control board, ventilation panet VP1 and the post accident sample panel. In January 1997, additional panels were identified that had not been included in the electrical separation inspections. A revised method for determining panels requiring electrical separation inspection to verify compliance was developed. Internal panel inspections using upgraded electrical separation criteria were performed during March and April 1997.
In October 1997, several electrical separation noncompliances were identified during a System Readiness walkdown and an Engineering Self Assessment.
The Final Safety Analysis Report (FSAR) specifies that a minimum six-inch separation (or a barrier) applies to spacing between exposed terminals, contacts, and equipment of redundant Class 1E circuits for testing and maintenance purposes. A minimum one inch separation (or a barrier)is required between redundant wire bundles or Class 1E and non-Class 1E wire bundles. Less than six-inches separation existed between the exposed terminals of the Train A portion of the Reactor Trip Switch and the Train B portion of the Reacter Trip Breaker indicating lights when the condition w s identified on June 10, 'i996. In addition, less than six-inches separation existed between the Train B portion cf the Raactor Trip Switch and the Train A portion of the Reactor Trip Breaker indicating lights on the main control board (MCB) and less than one-inch separation existed between wire bundles from the contacts associated with the Train A portion of the Reactor Trip Switch and wire bundles associated with the Train B Reactor Trip indicating Lights. These conditions may have existed since t.iitial plant startup.
Initial corrective action specified detailed inspections of vendor supplied equipment and other systems most vulnerable to electiical separation noncompliances. In sections 1 and 2 of the main control board, fourteen electrical separation noncompliances were identified on August 7,1996 In each case, the "as-found* condition failed to meet the minimum six-inch separation between exposed terminals, contacts, and equipment of redundant Class 1E circuits and/or the minimum one-inch separation between redundant wire bundles or Class 1E and non-Class 1E wire bundles. These conditions are reportable under 10CFR50.73(a)(2)(vii) as conditions that caused at least one independent train or channel to become inoperable in multiple systems. In no case were redundant trains of a system safety function affected.
in sechons 3 and 4 of the main control board, twenty one electrical separation noncompliances were identified on e
August 9,1996. In each case, the "as-found* condition failed to meet the minimum six-inch separation between exposed terminals, contacts, and equipment of redundant Class 1E circuits and/or the minimum one-inch separation between redundant wire bundles or Class 1E and non-Class 1E wire bundles. These conditions are reportable under 10CFR50.72(b)(2)(iii)(D) and 10CFR50.73(a)(2)(v)(D) as conditions that alone could have prevented the fulfillment of the safety function of systems that are needed to mitigate the consequences of an accident. An
:- immediate notification was made on August 9,1996 pursuant to 10CFR50.72(b)(2)(iii)(D). The immediate report._ _ - _... _ _ _ _ -
 
NRc FORJ 366A _
U.s. NUCLEAR REoVLAToRY CoMMisslON 84 96)
LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FACILITY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (6)
PAoE (3)
YEAR SEQUENTIAL Revision Millstone Nuclear Power Station Unit 3 05000423 NUMBER NUMBER 3 of 7 96 015 05 TEKT IIImore spaceis required, use additionalcopies of NRC form 366AI t1T)~
was associated with Train A and B Pressurizer backup heater and reactor vessel head vent isolation valve instrumentation failing to meet the minimum one-inch separation between redundant wire bundles. A further review concluded that several of the noncompliances identified are also reportable under 10CFR50.73(a)(2)(vii) as a condition that caused at least one independent train or channel to become inoperable in multiple systems. In these cases, no redundant trains of a system safety function were affected.
in sections 5 ano 6 of the main control board, twenty-four electrical separation noncompliances were identified on e
August 14,1996. In each case, the "as-found' condition failed to meet the minimum six-inch separation between exposed terminals, contacts, and equipment of redundant Class 1E circuits and/or the minimum one inch separation between redundant wire bundles or Class 1E and non-Class 1E wire bundles. These conditions are reportable under 10CFR50.73(a)(2)(vii) as conditions that caused at least one independent train or channel to become inoperable in multiple systems. In no case were redundant trains of a system safety function affected, in sections 7 and 8 of the main control board, ventilation panel VP1 and the post accident sample panel, twenty e
electrical separation noncompliances were identified on August 19,1996 and August 29,1996. In each case, the "as-found" condition failed to meet the minimum six-inch separation between exposed terminals, contacts, and equipment of redundant Class 1E circuits and/or the minimum one-inch separation between redundant wire bundles or Class 1E and non-Class 1E wire bundles. These conditions are reportable under 10CFR50.72(b)(2)(iii)(D) and 10CFR50.73(a)(2)(v)(D) for specific conditions found that alone could have prevented the fulfillment of the safety function of systems that are needed to mitigate the consequences of an accident. An immediate notification was made on August 19,1996 pursuant to 10CFR50.72(b)(2)(iii)(D). The immedLte report was associated with main steam isolation and control building isolation instrumentation failing to meet the minimum six-inch separation between exposed terminals, contacts, and equipment of redundant Class 1E circuits. A further review concluded that several of the noncompliances identified are also reportable under 10CFR50.73(a)(2)(vii) as ( condition that caused at least one independent train or channel to become inoperable in multiple systems. In these cases, no redundant trains of a system safety function were affected.
An engineering specification provides the electrical separation requirements for items intemal to control panels and cabinets.: Electrical separation requirements are summarized in the FSAR. The FSAR specifies that "where device arrangement precludes the minimum separation at exposed contacts or terminals, a barrier is provided. The barrier extends 1 inch beyond exposed contacts or terminals." The physicallayout of components on the main control board and ventilation panels precludes meeting separation requirements without the use of barriers. The barriers are g3nerally in the form of sheet metal enclosures surrounding a component. The design is such that one barrier can shield up to eight adjacent cornponents from interaction due to the six inch spatial requirement.
BIsed on the January 24,1997, event it was determined that not all panels were inspected. In addition after a subsequent identification of additional electrical separation noncompliances in panels previously inspected, management decided to reinspect the panels, including those that were previously inspected. A comprehensive inspection program wcs developed, Internal panelinsrections were performed during the time period from March through April 1997. As part of this inspection process, panels previously inspected were re-examined using the revised inspection criteria developed in response to this issue.__
The identified electrical separation specification deviations were in the following categories:
1.
Missing barriers between components 2.
Barrier not fitted tightly resulting in a slight air gap 3.
Barrier not extending one inch beyond the exposed contact or terminal NGC FORM 366A (4 95)
 
..U.s. NUCLEAR EE!ULAToHY CoMMESloN 14 958 LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION.
=
F ACILITY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (6)
PAoE (3)
YEAR sEoVENTIAL REvlsloN Millstone Nuclear Power Station Unit 3 05000423 NUMBER NUMBER 4 of 7 96 015 05 TsK1 (Ilmore space ls required. use additionalcopies of NRC form 366A) l11l
' 4.
Perforated material used as a barrier
: 5. Wires within one inch of each other The March and April 1997 inspections identified 782 deviations from electrical separation specification requirements. A
. deviation was identified when a requirement was not met between two adjacent components. Consequently, one barrier missing or improperly installed could result in up to eight separate electrical separation deviations. Tne vast majority of the identified electrical separation deviations occurred in the main control board and ventilation panel (VP1) and involved barrier installation problems.
On October 1,1997, a System Engineer during a system readiness walkdown identified two electrical separation noncompliances within the auxiliary shutdown panel (ASP - 3RPS*PNLAS). One noncompliance involved an adhesive ti3-wrap holder that had come loose allowing a safety related cable to come within one inch of nonsafety related wires.
The second noncompliance occurred because nonsafety related ASP door switch annunciator wires were found tie-wrtpped to a safety related cable bundle. These electrical separation noncompliances have been corrected. These conditions were determined reportable on October 9,1997, pursuant to 10CFR50.73(a)(2)(li)(B) as conditions outside tha design basis of the plant.
On October 7,1997, during an Engineering Self Assessment of the electrical separation inspection program, three clectrical separation noncompliances were identified within section 2 of the main control board. For each noncompliance th3 minimum one-inch separation requirement between Class 1E (wire) cable bundles or between Class 1E and non.
Cliss 1E (wire) cables bundles was not maintained. The three noncompliances involved not maintaining the required separation; -1) between wires from a device and a safety related cable bundle,2) between two safety related cables bundles where a separation device did not hold one of the cables far enough from the other and 3) between two safety rstated bundles where one bundle is attached to a bridge within the cabinet. These conditions were determined r: portable on October 9,1997, pursuant to 10CFR50.73(a)(2)(ii)(B) as conditions outside the design basis of the plant.
These conditions were discovered when the unit was in an extended cold shutdown and as a result no immediate operator action was required. Operability determinations were prepared for the electrical separation deviations identified, and corrective actions taken as required. Detailed records of the individual electrical separation deficiencies cr2 available at the Millstone Station.
11.
 
==Cause of Event==
The original root cause for the electrical separation noncompliances occurring since system tumover was considered to be inadequate job skills for maintaining electrical separation during the performance of maintenance and modifications.
This had been considered due to inadequate training and staff qualification associated with the electrical separation requirements identified in engineering specifications and the FSAR. Lack of training was considered to have applied to personnel who have been performing maintenance and implementing modifications and to planners in work control.
Contributing to this was a failure to develop adequate inspection plans for electrical separation criteria that resulted in inspections of inadequate scope.
A secondary cause, as originally considered, was that for a limited number of cases the failure to comply with the clectrical separation criteria existed prior to initial plant startup and was due to inadequate inspections by the Architect / Engineer.
NMC 70RM 306A (4-951
 
e
,yU.s. NUCLEAR REIULAToRY Commission to 951 LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION FActLITY t#":.t1)
DOCKET NUMBER (2)
LER NUMBER (6)
PAGE (3)
YEAR sEoVENTiAL Revision Millstone Nuclear Power Station Unit 3 05000423 NUMBER NUMBER 5 of 7 05-015 96 TEXT (if more space is required, use additionalcopies of NRC form 366A) (1 T)
Based on the number and type of electrical separation deviations identified during the March through April 1997, inspections, th6 majority of the failures to comply with the electrical separation criteria appears to be the result of inadequate installation and inspection prior to initial plant startup. These instances appear to have been due to inadequate ins,nections by the Architect / Engineer.
Several noncompliances were identified in October 1997, during a System Readiness Walkdown and a Self Assessment where the minimune one inch minimum electrical separation had not been maintained within the auxiliary shutdown panel and within section 2 of the main control board. These conditions are considered to be isolated occurrences.
~ lil,-- Analysis of Event The Final Safety Analysis Report (FSAR) specifies that a minimum six-inch separation (or a barrier) is required between cxposed terminals, contacts, and equipment of redundant Class 1E circuits. A minimum nf one-inch of separation (or a barrier)is required between redundant wire bundles for Class 1E and non-Class 1E wire bundles. These separation requirements are to prevent common cause failures and to provide physical protection between redundant Class 1E circuits during testing and maintenance.
There were no adverse safety consequences from this condition, in that the unit has not experienced an event cs a result of a failure in electrical separation nor has it experienced an event which was aggravated by a failure in Electrical separation of circuits or equipment. However, this condition is significant becaus3 the potential existed that thsse conditions could have prevented the fulfillment of the safety function of a system or systems needed to mitigate the consequences of an accident, or had caused at least one independent train or channel to become inoperable in multiple systems.
B sed on investigation it was originally concluded that the electrical separation of wiring internal to panels was provided in accordance with applicable specifications. As subsequent electrical separation inspection results indicate, based ca the number of specification deviations identified, the problems probably occurred mainly during original installation.
Between 1983 ano 1985, substantial modifications performed on the main control boards were not adequately inspe:ted for electrical separation in accordance with applicable specifications.
Between 1985 and 1996, many of the components associated with non-compliance with the six-inch separation criteria were caused by post startup maintenance and modification activities. However, in a few cases, during the original investigation, no maintenance activities could be identified which would have caused specific noncompliances.
Therefore, these instances were considered isolated cases of non-compliance with the six-inch, contact to contact, separation criteria that existed prior to initial plant startup as a result of iradequate inspections. (Subseq Jent electrical separation inspection results indicate, that, based on the number of specification deviations identified, that these isolated occurrences were actually indicative of the large number of installation prob! ems found during the March through April 1997, inspections ) Between 1983 and 1985, substantial modifications were performed on the main control boards. ' A r:; view of work orders associated with post startup maintenance and modification activities indicates that inspection plans failed to adequately identify electrical separation as an inspection attribute. In addition during this period no detailed training regarding requirements for electrical separation had been provided to individuals responsible for performance of maintenance and modifications.
NRC FORM 306A R951
 
4
.U.s. NUCLEAR REGULATORY Commission LICENSEE EVENT REPORT (LER)
TEXT CONTINUATION
~
F ACILITY NAME (1)
DOCKET NUMBER (2)
LER NUMBER (6)
PAGE (3)
YEAR SEQUENTIAL REVISION Millstone Nuclear Power Station Unit 3 05000423 NUMBER NUMBER 6 of 7 05 015 96 TEXT tri more space is required. use additionalcopies of NRC form 366Al t11l
 
==IV. Corrective Action==
No immediate actions were required on June 10,1996 as die plant was in a shutdown condition at the time of discovery end remained shutdown for unrelated reasons. Immediate corrective action was required for the Control Building isolation noncompliance that was discovered on August 19,1996. An entry into the Technical Specification Limiting Condition for Operation was made, and necessary repairs were initiated in addition, various components in multiple systems were declared inoperable after it was identified that the circuit and/or equipment failed to meet the applicable criteria for electrical separation.
Detailed ini.pections of vendor supplied equipment and other systems most vulnerable to electrical separation noncompliances were performed in response to the conditions discovered on June 10,1996. Due to the number of noncompliances identified, the inspection scope was expanded to include any equipment that might have contained both trcins of Class 1E cables or Class 1E and non-Class 1E cables. Inspections internal to electrical panels performed in response to the June and August 1996 events have been completed. These inspections identified additional separation noncompliances. On January 24,1997, additional panels were identified that had not been included in the electrical separation inspections, A revised method for determining panels requiring electrical separation inspection to verify compliance was developed. Following the January 24,1997, event an inspection of panel internals in March and April 1997 was performed using the upgraded electrical separation inspection criteria. In October 1997, several electrical separation noncompliances were identified within the auxiliary shutdown panel and within section 2 of the main control board. The results of these additional electrical panelinspections is presented in the Description of Events section of this LER.
The following corrective actions have been completed:
The applicable wt K planning process procedures have been revised to incorporate guidance for electrical e
separation inspection plan development.
j The internal electrical canelinspection program performed during March and April 1997 has been completed.
l e
Maintenance and modifications activities performed intemal to panels which could potentially impact electrical l
separation (performed during the period from June 1996 to November 1996) were originally intended to be reviewed prior to May 31,1997, to ensure compliance with training requirements and revised electrical separation criteria. Subsequently, due to the reinspection of the unit panels the need for this corrective action was negated.
initial training on electrical separation has been completed. A training module on electrical separation has been e
implemented as continuing training for applicable personnel from the implementing and Engineering departments.
The electrical separation noncompliances identified in October 1997 within the auxiliary shutdown panel have been corrected.
No further corrective actions are planned. The following corrective action remains to be completed:
Identified electrical separation noncompliances will be corrected or restored to compliance with the design basis e
prior to entry into Mode 4. (This corrective action includes those identified within section 2 of the main control board in OctoWr 1997.)-
 
I e
e Nec P0hhi 366A U.S. NUCLEAR RE;ULATORY COMMisslON LICENSEE EVENT REPORT (LER) l TEXT CONTINU ATION F ACILIT Y NAME lil DOCKEi NUMsER12)
LER NUMBER 16)
PAGE (3)
Y!AR SEOuEN(IAL REVIS'ON j
Villstone Nuclear Power Station Unit 3 05000423
. NUMDER NUMBER 7 of 7 f
06
~
015 96 a
T E K1 lit tmne space is required, use addetualcopies of NRC form 366A) l11t
!}
V.
Addittonal inf ormath!D None Sim3ar Events l
LERs discussing inadequate electrical installations from failure to maintain design conditions are identified below.
V rious elements of the Configuration Management Program are being conducted to these type of problems The LERs are:
i LER 96-045-00 *Flectrical Separation Design Conflict with FSAR" LER 96-049-01
* Class 1E to Non-Class 1E Electrical Cable Separation Noncomptance" i
Manuf actu er Data gil.S_Svstem Code PI:nt Protection System (Manual Reactor Trip). JC i
Reactor Coobnt System (Pressi riter Heater). AB Reactor Coolant System (Head. ent isolation). AB Main Steam (Drainline) Isolation SB Controi Building Isolation VI Nehttect Enaineer Stone & Webster Engineering Corp.
i i
i CC &ORM 366A 44 pli
- -,.. - -.., -...., _...., _ _. ~,,,
}}
 
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