ML20246B433

Ack Receipt of Informing NRC of Steps Taken to Correct Violations Noted in Insp Rept 50-382/89-11

ML20246B433
Person / Time
Site:	Waterford
Issue date:	06/28/1989
From:	Milhoan J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:	Dewease J LOUISIANA POWER & LIGHT CO.
References
NUDOCS 8907070334
Download: ML20246B433 (2)

See also: IR 05000382/1989011

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[E'* JUN 2 81989

In Reply Refer:To:

Docket.: 50-382/89-11

' Louisiana Power & Light Company

ATTN: J. G. Dewease, Senior Vice President  ;

Nuclear Operations

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317 Baronne Street

New Orleans, Louisiana 70160

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. Gentlemen:

Thank you for your letter of June 9,1989, in response to our letter and

i. Notice of Violation dated May 10, 1989. We have reviewed your reply and find-

it responsive to the concerns raised in our Notice of Violation. We will

review the implementation of your corrective actions during a future j

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. inspection to determ ae that full compliance has been achieved and will be

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maintained.

Sincerely,

Original Signed By

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James L.1 Milhoan, Director

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Division of Reactor Projects

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cc:

Louisiana Power & Light Company

ATTN: R. P. Barkhurst, Vice President

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Nuclear Operations

P.O. Box'B '

K111ona:, Louisiana 70066

Louisiana Power & Light Company

ATTN: J. R. McGaha, Jr., Plant Manager

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LATTN: J^R.: F. Burski, Manager, Nuclear i

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June 9, 1989

W3P89-3048

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ti.S. Nuclear Regulatory Commission

ATTN: Document Control Desk

Washington, D.C. 20S55

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Subject: Waterford 3 SES JUN I 51989 ..

Docket No. 50-382 ,

License No. NPF-38

NRC Inspection Report 89-11

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Gentlemen:

In accordance with 10 CFR Part 2.201, Louisiana Power & Light hereby submits

in Attachment 1 the response to the Violation identified in Appendix A of the

subject Inspection Report.

If you have any questions concerning this response, please contact T.J. Gaudet

at (504) 464-3325.

Very truly yours,

"

R.F. urski

Manager

Nur. lear Safet.y f: Regulatory Affairs

RFB:TJG:ssf

Attachment

cc: -R.DT Martin,4NRC Region IV

F.J. liebdon, NRC-NRR

D.L. Wigginton, NRC-NRR

NRC Resident Inspectors Office

E.L. Blake

W.M. Stevenson

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"AN EQUAL OPPORTUNITY EMPLOYER"

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Page 1 of 4

H . ATTACHMENT 1

lE LP&L Response ' to ' the Violation Identified in Appendix A'-

of Inspection Report 89-11

VIOLATION NO. 8911-01

Inadequate Design Control

Criterion IIIzof Appendix B to'.10 CFR Part 50 states,'in'part, " Measures

ihall be established to assure that applicable regulatory requirements and

the design basis, as defined in 10 CFR 50.2 and as specified in the license

application, for those structures, systems, and components to which this

appendix applies are correctly translated into specifications, . drawings,

procedures,-and instructions.... The design control measures shall provide

for verifying or checking the adequacy of design, such as by the

performance of design . reviews, by the use of alternate or simplified

calculational methods, or by the performance of a suitable testing

program ..." This is implemented by the-licensee's approved Quality

Assurance Plan.

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Contrary to the above, the following examples of the failure to control the

facility design adequately were identified:

1. Containment sump recirculation valves' backup air supply accumulators

' were not designed or tested to ensure proper system operation for all

conditions postulated by the design basis.

2. Static uninterruptible power supply 3A-S was mo'dified by the addition

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of a nonsafety-related load to the distribution panel without

accounting for the effects of load faults on the inverter operation.

.These examples are a Severity Level IV violation.

P".SPONSE

(1) Reason For The Violation

Example 1

The root cause of the deficiency cited in example I was an inadequate

review of design requirements for the noted air accumulators.

Safety injection sump recirculation isolation valves SI-602 A&B are

air actuated, safety-related valves that are required to be closed

during the safety injection phase and to open on a recirculation

actuation signal (RAS) during a design basis event. The Instrument

Air System (IA) normally positions the valves. In the event of a loss

of IA, air accumulators are provided to supply air to operate these

valves. The installation specifications for the SI-602 A&B

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accumulators were based on a large break loss of coolant accident'

(LOCA) with IA not available and a RAS generated within one hour.

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'Accordingly,-the accumulators were designed to maintain sufficient .

pressure to perform their function for one hour. The accumulators j

were not reevaluated during construction to ensure that they were

adequately designed for the,small break LOCA. During a small break

LOCA scenario, the valves may be required to operate longer than one

hour after the IA supply is-compromised. (Small break 10CA's are.the

limiting accident for determining the_ length of time after a LOCA that .

the valves must be-able to function.)

)

The possibility that these valves may need to operate beyond the

existing one hour limit was identified _ during LP&L's evaluation of

Generic Letter 88-14, " Instrument Air Supply System Problems _Affecting )

Safety Related Equipment." Thus, in January, 1989, Problem

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Evaluation /Information Request (PEIR) 10673 was generated to further

evaluate this concern.

On March 30, 1989 a Nonconformance Condition Identification (NCI

262265) was. issued to expedite the engineering evaluation. Then on

March 31, 1989, the situation was determined to be reportable as in

unanalyzed-condition that has existed since initial startup. (Note:

This information has been submitted to the NRC in LER-89-007 via LP&L-

Letter No.'W3A89-0129 dated 5/1/89.)

Example 2

The root.cause of the deficiency cited in example 2 was a design

inadequacy that occurred during the design phase of the Waterford 3

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static uninterruptible power supplies (SUPSs). A brief discussion on

the d(sign is provided below. At this point, it is important to note  !

that.the inadequate design relates to the design philosophy of the

SUPS that was originally established by the Waterford 3 Architect

Engineer and not to a deficiency in meeting the regulatory

requirements. l

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Typicallyr SUPS design incorporates an automatic static transfer <

switch for instantaneous transfer to a bypass source in the event of a j

fanlt on the SUPS output or on feeder circuits. This bypass source 1

provides high current for tapid clearance of the faulted circuit.  ;

During the design phase of the Waterford 3 SUPS, a conscientious j

decision had to be made on whether or not to install this automatic j

static transfer switch feature. At that time, the NRC and the i

industry identified several concerns with the operation of

cointerruptible power supplies (UPSs) (Reference: NRC (AEOD) Case l

Study Report - Operational Experience Involving Losses of Electrical

Inverters, December 1986). In particular, several failures of static

transfer switches had occurred due to problems with solid state

devices used in these switches. These failures led to degradation of

the inverter and/or the entire UPS system, and the reliability of the

static transfer switch was in question. Based on the these concerns,

there appeared to be no advantage in providing the automatic static

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transfer switch for fast fault clearances. Accordingly, Waterford 3

(and some other PWRs) chose not to incorporate this feature into the

SUPS design.

The IE SUPS at Waterford 3 (3A-S and 3B-S which are manufactured by

Elgar Corporation) are 10 KVA safety-related power supplies that feed

power distribution panels (PDP) 390-SA and 391-SB, respectively. The

SUPS are required for normal operation of the plant and safe shutdown

during a design basis accident condition. The existing design feature

is such that a fault on any load feeder circuit with an instantaneous

demand of 165% full load amps will drive the ZA-S/3B-S SUPS into

shutdown condition for 0.5 seconds before driving it into the current

limiting mode. The protective devices on the feeder may not trip fast

enough to isolate the faulted circuit.

During a design basis accident, non-1E loads are postulated to fail in

an adverse manner. PDP 390-SA has a non-1E load (Telephone Cabinet

PEC 2) on Circuit No. 65. (Note: At that time, the Architect

Engineer considered communications to be a vital part of the plant and

therefore elected to make such a connection.) Thus, a failure of the

non-safety telephone cabinet during a design basis accident has the

potential to momentarily shutdown the 1E SUPS and degrade the Class IE

system.

The original understanding of the design was that upon the inception 4

of a fault, the SUPS would supply up to 150% full load amps and then '

go into current limiting mode. In the event that the current limiting

mode failed, the 165% shutoff limit would protect the inverter from

severe damage. This arrangement was considered a backup protective

feature. The fact that the SUPS could overshoot to the 165% shutoff

limit befor'e getting into the 150% current limiting mode condition was i

not obvious and only realized after the vendor was persistently

questioned.

There are four more Class IE SUPS at Waterford 3, which are of similar

design but different manufacture. These SUPS do not have the backup

shutoff feature. Consequently, as far as LP&L was concerned, the

connecting loads associated with the SUPS had no bearing on the

design.

(2) Corrective Steps That Have Been Taken And The Results Achieved

Example 1

A detailed engineering evaluation was performed to address this

concern as documented in NCI 262265. The results of the evaluation

(as amended on 4/20/89) indicated that adequate operating pressure in

the accumulators could be maintained for the limiting small break LOCA

(0.01 ft )2 in which a RAS is predicted to occur within 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br />. A

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graph of required IA header pressure versus maximum allowable

accumulator pressure decay rate was developed. Operations issued

Standing Instruction 89-04 to establish IA operation based on the IA

header pressure graph. Until a permanent solution is implemented, the  ;

IA system pressure will be monitored and controlled by Operations '

Standing Instruction 89-04.

Example 2

A Nonconformance Condition Identification (NCI 262261) was generated

on 3/30/89 to formally address and document corrective actions for the

potential loss of power condition for SUPS 3A-S during design basis

accident conditions.

On 3/31/89, Circuit No. 65 of PDP 390 was disconnected from SUPS 3A-S

at the local terminals in the cabinet. Temporary power from a

non-safety supply (PDP 3014 Circuit No. 5) was then provided to

telephone cabinet PEC 2 under a temporary alteration (TA 89-009).

All loads on PDP 390-SA and PDP 391-SB were reviewed to ensure that no

other non-1E loads existed.

(3) Corrective Steps Which Will Be Taken To Avoid Further Violations

Example 1

Station Modification Request (SMR) SI-007 has been issued to propose

several solutions to ensure long term operation of valves SI-602 A&B

after a LOCA with a simultaneous loss of IA.

PEIR 71128 has been initiated to review the design basis of the air

and nitrogen accumulators with respect to small break LOCAs.

Example 2

A deaign change will be implemented to make TA 89-009 a permanent

installation. (Note: Station Modification Request No. SMR ID-003 has

been generated to accomplish this task). Also, the drawings for PDP

390-SA and PDP 391-SB will be marked to ensure that non-1E loads are

not added to them in the future.

(4) Date When Full Compliance Will Be Achieved

Example 1

The design basis review of the accumulators is expected to be complete

by December 31, 1989. Permanent installation of one of the proposed

solutions of SMR SI-007 is expected by Refuel No. 4, at which time

LP&L will be in full compliance.

Example 3

The design change (DC 3180) and drawing revision are scheduled for  !

completion by 12/31/89, at which time LP&L will be in full compliance. I

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