ML20155F060

Enforcement Conference Rept 50-271/86-05 on 860319.Areas Discussed:Failure of Standby Liquid Control (SLC) Sys During 860208 Test & Factors Causing Inoperable SLC from 840711 Until 860208

ML20155F060
Person / Time
Site:	Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date:	04/14/1986
From:	Elsasser T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:
Shared Package
ML20155F047	List: ML20155F043 ML20155F060
References
50-271-86-05-EC, 50-271-86-5-EC, NUDOCS 8604210134
Download: ML20155F060 (5)

See also: IR 05000271/1986005

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U.S. NUCLEAR REGULATORY COMMISSION

REGION I

Report No. EC 86-05

Docket No. 50-271

License No. DPR-28

Licensee: Vermont Yankee Nuclear Power Corporation

RD 5, Box 169, Ferry Road

Brattleboro, Vermont 05301

Facility Name: Vermont Yankee Nuclear Power Station

Type of Meeting: Enforcement Conference

Meeting At: NRC Region I, King of Prussia, Pennsylvania

Meeting Date: March 19, 1986

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Prepared By: Wi -

. ond,Senjnr_ResidentInspector

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Approved by: _ . 44-d' _

ThomasC.'Elsasg ef Rea K Njects Section 3C ' Date

Meeting Summary: An Enforcement Conference was held at NRC Region I, King of

Prussia, Pennsylvania, on March 19, 1986 to discuss the findings of Special In-

spection No. 50-271/86-05. That inspection was conducted to review the failure

of the Standby Liquid Control (SLC) system during a test on February 8,1986, and

to identify the factors that caused the SLC to be inoperable from July 11, 1984

until February 8, 1986. Operation of the reactor for core operating Cycle XI was

in violation of Technical Specification 3.4.A. The meeting was attended by NRC

and licensee management and lasted about two hours, during which the circumstances

associated with the event and the licensee's proposed corrective actions were

discussed.

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DETAILS

1. Meeting Attendees

a. Vermont Yankee Nuclear Power Corporation

D. McElwee, Senior Engineer - Operations Support

W. Murphy, Vice President and Manager of Operations

R. Wanczyk, Technical Services Superintendent

b. Nuclear Regulatory Commission

J. Allan, Deputy Regional Administrator

T. Elsasser, Chief, Reactor Projects Section 3C

P. Eselgroth, Chief, Test Programs Section

D. Holody, Enforcement Specialist

W. Kane, Deputy Director, Division of Reactor Projects

W. Raymond, Senior Resident Inspector

R. Starostecki, Director, Division of Reactor Projects

L. Tripp, Chief, Reactor Projects Section 3A

E. Wenzinger, Chief, Reactor Projects Branch 3

2. Summary of Discussion

Mr. Starostecki opened the meeting and participants were introduced.

Mr. Starostecki summarized the event as described in Inspection Report 86-05

and requested Vermont Yankee representatives to address NRC concerns associ-

ated with the inoperable Standby Liquid Control System (SLC), including: how

the system became inoperable; the apparent loss of configuration control fol-

lowing a design change on the SLC system; and, the deficiencies in the pro-

curement and pre-service testing programs which did not detect a vendor pro-

duct change that affected the operability of a safety system.

Following opening remarks by Mr. Murphy, Mr. Wanczyk and Mr. McElwee gave a

presentation that summarized the sequence of plant actions associated with

the event, the licensee comments on the Inspection Report 86-05, and the cor-

rective actions taken and planned to prevent recurrence. The summary of lic-

ensee actions covered the period from February 8-18, 1986, and included the

sequence of plant activities following the failure of the 14A SLC squib valve

to fire during testing per OP 4114 on February 8, 1986. Management involve-

ment in the review of the event was evident. Licensee actions to provide

timely notifications to the NRC and other users of potentially defective

vendor parts were also evident.

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The licensee provided comments in three areas of Inspection Report 86-05, re-

garding statements that could be potentially misleading. The Summary section

of the report (page 1) noted that the as-found firing circuit wiring differed

from the wiring design drawing. Further, on page 2 of the report, the NRC

staff noted that the as-found wiring in the local terminal boxes appeared

" rolled" into a sequence different than that depicted by control wiring draw-

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ings (CWDs) B191301 Sheets 1200 and 1201. The licensee stated that the as-

found wiring was functionally the same as the design specified by SIL 186,

and further, that the sequence of the wires shown on the CWD was not pertinent

to the functional design basis of the circuit, but only provided for clarity

in depicting the circuit terminations. The-licensee stated further that the

SIL design basis was not to make a circuit that would be acceptable for a

primer chamber of a type different than that installed during the modifica-

tions in 1977.

The NRC staff agreed that implementation of the 1977 modifications resulted

in a circuit that was functionally correct per the SIL design. However, field

changes to the circuit as described in the installation procedure were made

which were not properly documented. The NRC staff maintained that the failure

to properly document the 1977 field changes constituted a loss of licensee

control over the wiring configuration, since the CWDs are the only controlled

drawings provided to depict the electrical configuration of station electrical

circuits, and are used by plant personnel as both electrical schematics and

wiring diagrams. The NRC staff agreed, as stated in the report, that had the

field changes been properly documented in 1977, they would have been approved.

Thus, the causes for the SLC system failure remained the primer manufacturing

error, and the failure by the manufacturer and the licensee to detect the

error prior to use of the primer chambers. Additionally, it also remains

true that had the firing circuit field modification not been made, the im-

properly manufactured primers would have fired the squib valves and allowed

the SLC to function as designed.

The licensee commented further on a statement made on page 6 of the report

concerning the actions by an Instrumant & Control technician while working

on the SLC firing circuits in 1983. The licensee stated that the technician

did not recognize a discrepancy between the as-found circuits and the CW0s

in 1983, but only noted that the wiring color coding was not carried through

the local terminal boxes. The NRC staff acknowledged the licensee's comments

and noted that the clarification had no bearing on the outcome on the staff

enforcement action for the issue.

The licensee suggested that the NRC staff reconsider the information provided

to the industry in Information Notice 86-13 dated 2/21/86 which described the

SLC failure at VY. The licensee noted that information in the notice attri-

buted the failure to wiring errors both internal and external to the primer

chambers, when in fact, the primer wiring error alone could cause a problem

at another facility. The NRC staff stated that this information would be

reviewed and the need to reissue information on this subject would be recon-

sidered.

The licensee summarized the scope and status of corrective actions that have

or will be t'aken to prevent a recurrence of the event, which included the

actions summarized below.

(1) Revise procedure 0P 4203 to: include a pin-to pin continuity check of

new primer chambers prior to installation in the firing circuits; change

the method of test firing the primers in the circuit, such that the in-

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situ testing will be on a primer from a batch to be used for the upcoming

operating cycle; and, address additional precautions regarding the proper

handling of the explosive charges. The revised procedure is expected

to be issued by April 17, 1986.

(2) Update and correct CWD drawings B191301 Sheets 1200 and 1201. The draw-

ing changes were initiated on March 17, 1986. Additionally, the licensee

will review drawings for control room panel 9-5 to identify and make

needed clarifications.

(3) Procedure changes will be made to enhance procurement controls and speci-

fically to require that drawings will be requested and reviewed by plant

personnel for subsequent orders of the parts. The existing primer cham-

bers in stores will be clearly marked to assure shelf life limits are

observed and out-of-date charges will be disposed. Additionally, by memo

dated March 17, 1986, Yankee NSD was requested to reevaluate the primer

chamber vendor's QA program and to make recommendations by April 17, 1986

regarding subsequent orders from the vendor.

(4) In the area of design control, the licensee will complete a revicw by

April 17, 1986 to assure that present procedures assure that as-built

drawings are completed as part of the design change process. Maintenance

request 86-0524 has been initiated to arrange the primer pigtail wiring

to reflect the sequence specified by the CWD, and thereby make the cir-

cuit wiring compatible with either type of primer chamber. Additionally,

surveillance procedures will be reviewed by April 17, 1986 to identify

any other tests which provide an after-the-fact operability demonstration

of the tested system. The as-built circuit configuration will be veri-

fied for any test so identified. The Traversing Incore Probes (TIP) were

the only systems identified as of March 19, 1986 that required additional

review.

(5) Additional tests and checks will be completed using an upgraded version

of OP 4203 prior to declaring the SLC sytem operable. This will include

a continuity check of all charges withdrawn from stores, and in-situ test

firing of one charge from the batch to be used.

(6) The licensee will complete an evaluation by April 17, 1986 to determine

whether design changes to the squib continuity monitoring circuit would

be warranted to make it foolproof. The licensee's preliminary assessment

for this item is that such a monitoring circuit would not be cost effec-

tive, and the existing design is sufficient so long as configuration

controls are maintained.

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(7) The licensee agreed to consider whether the SLC technical specifications

(3/4.4) should be revised to better define the intended surveillance test

requirements.

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3. Conclusion of Meeting

Mr. Murphy summarized the licensee's presentation by making the following

points: (i) the SLC system was inoperable for 1 operating cycle; (ii) the

cause for the SLC being inoperable was the manufacturing error in the primer

chambers, as substantiated by the vendor's Part 21 report; (iii) the system

design and testing procedures in place since 1977 were adequate to assure an

operable system, except that the procedure for bench testing the charges could

have been more detailed and the in-situ testing could have been better;

(iv) the loss of configuration control did not contribute to the loss of

operablility, but did create an inadequacy in the documentation; and, the

plant's followup actions were timely and comprehensive.

Mr. Starostecki concluded the meeting by stating the Region I staff would

evaluate the licensee's corrective actions and that a decision regarding the

appropriate enforcement action would be forthcoming.

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