05000339/LER-1981-001-03, /03L-0:on 810101,average RCS Temp Outside Tech Specs on Two Occasions.First Caused by Vol Control Tank Being Overborated;Second by Overcooling Primary.Steam Generator Blowdown Secured,Rods Withdrawn & RCS Diluted

/03L-0:on 810101,average RCS Temp Outside Tech Specs on Two Occasions.First Caused by Vol Control Tank Being Overborated;Second by Overcooling Primary.Steam Generator Blowdown Secured,Rods Withdrawn & RCS Diluted

ML19341A472
Person / Time
Site:	North Anna
Issue date:	01/15/1981
From:	Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
Shared Package
ML19341A467	List: 05000339/LER-1981-001, Forwards LER 81-001/03L-0 05000339/LER-1981-001-03, /03L-0:on 810101,average RCS Temp Outside Tech Specs on Two Occasions.First Caused by Vol Control Tank Being Overborated;Second by Overcooling Primary.Steam Generator Blowdown Secured,Rods Withdrawn & RCS Diluted
References
LER-81-001-03L, LER-81-1-3L, NUDOCS 8101230601
Download: ML19341A472 (3)

LER-1981-001, /03L-0:on 810101,average RCS Temp Outside Tech Specs on Two Occasions.First Caused by Vol Control Tank Being Overborated;Second by Overcooling Primary.Steam Generator Blowdown Secured,Rods Withdrawn & RCS Diluted

Event date:
Report date:
3391981001R03 - NRC Website

text

Y 3

V U.S. NUCLEAR REGULATORY COMMISSION LICENSEE EVENT REPORT CONTROL BLOCK / / / / / / / (1)

(PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION)

/0/1/

/V/A/N/A/S/2/ (2)

/0/0/-/0/0/0/0/0/-/0/0/ (3)

[4/1/1/1/1 (4)

/ / / (5)

LICENSEE CODE LICENSE NUMBER LICENSE TYPE CAT

/0/1/

/L/ (6)

/0/5/0/0/0/3/3/9/ (7)

/0/1/0/1/8/1/ (8) /o/1/1/s/a/1/ (9)

E DOCKET NUMBER EVENT DATE REPORT DATE EVENT DESCRIPTION AND PROBABLE CONSEQUENCES (10)

[0/2/

/

On January 1,1981, with Unit II at 2% power in Mode 2, the average reactor

/

/0/3/

/

coolant system temperature was less than 541*F on two occasions. However, on /

/0/4/

/

each occasion, the temperature was restored to within its limits (2541'F) with-/

/0/5/

/

in 15 minutes as required by the Technical Specifications. Consequently, the /

/0/6/

/

health and safety of the public were not affected.

/

/0/7/

/

/

/0/8/

/

/

SYSTEM

CAUSE

CAUSE COMP.

VALVE CODE CODE SUBCODE COMPONENT CODE SUBCODE SUBCODE

/0/9/

/I/E/ (11) /D/ (12) /Z/ (13) /Z/Z/Z/Z/Z/_Z/ (14) g/ (15) g/ (16)

SEQUENTIAL OCCURRENCE REPORT REVISION LER/R0 EVENT YEAR REPORT NO.

CODE TYPE NO.

(17) REPORT NUMBER

/8/1/

/-/ /0/0/1/

/\\/

/0/3/

/L/

/-/

LO/

ACTION FUTURE EFFECT SHUTDOWN ATTACHMENT NPRD-4 PRIME COMP. COMPONENT TAKEN ACTION ON PLANT METHOD HOURS SUBMITTED FORM SUB. SUPPLIER MANUFACTURER

/X/ (18) /G/ (19) /Z/ (20) /Z/ (21) /0/0/0/0/ (22) LY/ (23) /N/ (24) /2/ (25) /Z/9/9/9/(26)

CAUSE DESCRIPTION AND CORRECTIVE ACTIONS (27)

/1/0/

/The first event occurred as a result of the volumn control tank (VCT) being in-/

/1/1/

/ advertently overborated while excess letdown was in service, and prior to

/

/1/2/

/ initiating normal letdown. The second event occurred as a result of

/

/1/3/

/ overcooling the primary with the condenser steam dumps. Temperature was restored /

/1/4/

/by securing steam generator blowdown, withdrawing rods and diluting the RCS.

/

FACILITY METHOD OF STATUS

% POWER OTHER STATUS DISCOVERY DISCOVERY DESCRIPTION (32)

/1/5/

LCL (28)

/0/0/2/ (29) /

NA

/ (30)

LAf_ (31) L, Operator Observation

/

A ACTIVITY CONTENT RELEASED OF RELEASE AMOUNT OF ACTIVITY (35)

LOCATION OF RELEASE (36)

/1/6/

/Z[ (33)

/Z[ (34) /

NA

/

/

NA

/

PERSONNEL EXPOSURES NUMBER TYPE DESCRIPTION (39)

/1/7/ /0/0/0/ (37) g[ (38) /

NA

/

PERSONNEL INJURIES NUMBER DESCRIPTION (41)

/1/8/ /0/0/0/ (40) /

NA

/

LOSS OF OR DAMAGE TO FACILITY

~

}

TYPE

DESCRIPTION

/1/9/

/Z/ (42) /

NA

/

PUBLICITY ISSUED DESCRIPTION (45)

NRC USE ONLY

/2/0/

/N/ (44) /

NA

/////////////

NAME OF PREPARER W. R. CARTWRIGHT PHONE (703) 894-5151 8101280 W

^$

Virginia Electric and Power Company North Anna Power Station, Unit 2 Attachment: Page 1.of 2 Docker No. 50-339 Report No. LER 81-01/03L-0 1

Description of Event

On January 1,1981, with Unit II in mode 2 at 2% power (and 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br /> following a 100% reactor trip), the average reactor coolant system (RCS) temperature was less than 541' on two occasions; one duration of 10 minutes and one duration of 3 minutes.

In each occurrence average RCS temperature was brought within its normal parameters 2 541 'F within 15 minutes as required by Tech. Specs.

This event is contrary to T.S.

3.1.1.5, and reportable pursuant to T.S. 6.9.1.9.b.

Probable Consequences of Occurrence Since RCS average temperature was brought within specifications as required by the action requirements of the limiting conditions for Operations, the health and safety of the public were not affected.

1

Cause of Event

This event occurred as a result of changing modes of operation of the VCT (by dilution and boration) during a preceding reactor startup in order to compensate for reactivity changes due to xenon with dilution required while xenon is building in and boration required while xenon is decaying out. Prior to and during this startup, excess letdown was in service due to a failed letdown isolation valve in the normal letdown line. Consequently, boron concentration in the VCT increased and when normal letdown was restored, the normal flows from the VCT to the RCS increased substantially resulting in a decreasing RCS average temperature as normal letdown was being initiated, and before the appropriate action could be taken.

i In the second case RCS temperature fell less than 541'F while being controlled through manual manipulation of a condenser st'eam dump. The valve was opened a turn rather than closed a turn as a result of a misunderstanding in communication between the individuals involved.

This misunderstanding was quickly corrected.

Immediate Corrective Action

The immediate corrective action was to secure steam generator blowdown, commence dilution, and wicadraw control rods until RCS average temperature was restored to 2 541 *F.

J Scheduled Corrective Action There is no scheduled corrective action required.

D a

l Attachment: Page 2 of 2 Actions Taken to Prevent Reccurrence 1

For the first event, the operation procedure associated with shifting from excess letdown to normal letdown will be changed to add the appropri-ate precautions necessary to insure that proper boron concentrations exist in the VCT prior to initiating normal letdown, and that possible power and temperature changes can take place after initiating normal letdown.

For the second event, the occurence was discussed with the individuals involved. Corrrect communications and instructions were stressed.

Generic Implications There are no generic implications to this event.

l l