ML19347C883

Responds to IE Bulletin 80-17,Suppl 4, Failure of Control Rods to Insert During Scram at Bwr. Sys Consists of Sensor, Transmitter,Alarm Unit & Remote & Local Indicators.Sensing Device Is Capacitance Probe

ML19347C883
Person / Time
Site:	Vermont Yankee File:NorthStar Vermont Yankee icon.png
Issue date:	01/30/1981
From:	Heider L VERMONT YANKEE NUCLEAR POWER CORP.
To:	Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
References
FVY-80-18, IEB-80-17, IEB-80-17-S4, NUDOCS 8103100229
Download: ML19347C883 (8)

Text

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s VERS 10NT YAN KEE NUCLEAR PbWER CORPORATION SEVENTY $EVEN GROVE STREET RUTLAND. VERMONT 05701 8

ENGINEERING OFFICE 1671 WORCESTER ROAD FRA MINGH AM, M ASSACH US ETTS o17of January 30, 1981 7s'<PMoa s *'7-*72 ='oo W

s United States Nuclear Regulatory Commission O

A Office of Inspection and Enforcement V

Region I 631 Park Avenue J

King of Prussia, Pennsylvania 19406 Eg'9 9

1,.'h ap%

O Attention:

Mr. Boyce H. Grier, Director

References:

(a)

Llcense No. DPR-28 (Docket No. 50-27 %

0 (b) USNRC Letter to VYNPC, dated December 1,.

IE Bulletin NO. 80-17, Supplement No. 4

Subject:

Response to IE Bulletin No. 80-17, Supplement No. 4

Dear Sir:

This letter is in response to Reference (b) which deals with the failure of a water level indication system to detect water in the cram discharge volume (SDV) following a scram. Although Supplement 4 dea's siith an ultrasonic syste.m failure, we are responding to the required generic questions applicable to our system.

In response to this request, the following is provided:

ITEM 1:

Bench Test of CMS a.

The system consists of a sensor, transmitter, alarm unit and remote and local indicators. The sensor is a capacitance probe of the immersion type, which supplies a signal to a transmitting un't.

The transmitter converts the capacitance signal to a varying current which supplies a series wired local indicator, alar:a unit, and remote indicator.

The alarm unit supplies a common annunciator for both North and South scram discharge volumes. The annunciator and remote indicators are in close proximity to one another in the =ain control room.

The accompanying drawings depict the system layout. The only deviation-is that the Setcon alarm unit is contained within the transmitter case instead of being mounted separately.

b.

The sensing device, as mentioned before, is a capacitance probe which' changes its value as the dielectric of the medium around the probe changes. Specific characteristics are as follows:

8103100 M q

. - - =. - _ _. _ _. - _ -

l

. United Statos Nuclear Rsgulatory Commission j

Jrnuary 30, 1981 Pag 3 2 0

1.

Ambient temperature limits: -400 to 140 F 2.

2 5 pf per 30 F change or.15 pf for an 4

operating range of 6.0 to 4x10 pr.

3 Linearity: 3 5%

4.

Time response 20 milliseconds (to 905 of final value);

this response is not effected by temperature.

! ~

5 Conductance factor "G" equal to 4.

6..

Conductivity dielectric constant ratio.36 micromhos per centimeter - defines when bare probe can be used. Vermont 4

Yankee system used insulated probes which can be used for any material, independent of above ratio.

7 System accuracy: 2 15 of span or 3 1/16 of one inch.

c.

System calibration is determined by application, i.e., as a I

transmitter or proportional controller. Vermont Yankee uses a transmitter system.

The sensor is mounted within 24' of the transmitter. There are no transmission losses for the current loop within the range of 0-400 ohm loop resistance.

The system i

is calibrated prior to installation and the additional capacitance effects are zeroed out after installation. The option exists within the system to add external capacitance if required to compensate for the effects 'of the installation.

d.-

All testing and calibration of this. system is performed by the Instrument and Control Department Technicians.

All these individuals are qualified to. test and maintain Technical Specifications and/or Safety Related equipment.

This system is not more sophisticated or of greater importance than those systems related to usafe shutdown or accident control.

I ITEM 2:

Operability Test of CMS Following receipt of material and prior to installation, a bench test was performed using the vendor supplied Technical Manuals for direction.

The test was completed satisfactorily.

As directed by;the test procedure included.with the design package, p

an - operability test was performed following-the installation.

Water was admitted to the scram discharge volume header by

.backfilling the instrument. volume.

An ultrasonic measuring device

'(portable) was used to verify level, and final span adjustments were performed.

4-

' ITEM 3:

Interim Manual Surveillance -

This item.is notH applicable to _ Vermont Yankee.

Plant was shutdown "at time of Bulletin receipt. : The -CMS was installed and fully tested priorito startup.

V

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O-i-

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Unitcd Stat 3s Nuclsnr R2guletory Commission J nuary 30, 1981 Page 3 Response to IE Bulletin No. 80-17, Supp. No. 4 - Items 4, 5, and 6 ITEM 4:

Full Test of CMS to be Conducted During a Planned Outage Following the installation and prior to plant startup, an in-place operability test was performed by observation of several f' low rates in the SDV.

Different responses were observed in each case.

Flows were observed at both ambient or reduced temperature and pressure, and normal operating temperature and pressure.

Flow rates varies from a full scram condition to a single scram.

In addition, approximately two gallons of water were added to the SDV header to ensure the vent paths were clear.

Level indication for all flows responsed as expected and returned to normal following SDV header draining.

ITEM 5:

Operability of CMS During Reactor Operation ITEM 6:

Operating Procedures At Vermont Yankee, the CMS was installed and made fully operable in December 1980.

As previously described, the system was calibrated and functionally tested in accordance with manufacturers recommendations. Procedures are in use that require control room personnel to perform an instrument check once per shift.

Presently approved procedures also give operations personnel instructions on the use of the CMS as well as the response required in the event of alarms or other abnormal conditions. These procedures will be expanded by March 1, 1981 to cover actions to be taken in the event the CMS is determined to be inoperable. Surveillance procedures including functional testing, calibration, and repair are presently under development and will be issued prior to the input scheduled su rveillance.

The 'following information is ' submitted in response to your request for estimates of manpower expended in the research and subsequent performance of actions associated with this Bulletin.

Manpower Requirements Hours Bulletin Response 25 Corrective Actions N/A We trust the above supplied information is satisfactory; however, should you desire additional information, please contact us.

Very truly yours, VERMONT YANKEE NUCLEAR POWER CORPORATION L. H. Heider Vice President

Unitcd Stat 0c Nucloce R2gulatory Commission January 30, 1981 Pag 3 4 COMMONWEALTH OF MASS ACHUSETTS)

)ss COUNTY OF WORCESTER

)

Then personally appeared before me, L. H. Heider, who, being duly sworn, did state that he is a Vice President of Vermont Yankee Nuclear Power Corporation, that he is duly authorized to execute and file the foregoing request in the name and on the behalf of Vermont Yankee Nuclear Power Corporation, and that the statements therein are true to the best of his knowledge and belief.

N6berf. H. Groce '

Notary Public

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