05000280/LER-1978-035-01, /01T-0 on 781109:study of Calibr Techniques Showed That SI Accumulators Indicated Level Would Be Lower than Actual Level.Discovered After Rigorous Review of Factors Affecting Instru

/01T-0 on 781109:study of Calibr Techniques Showed That SI Accumulators Indicated Level Would Be Lower than Actual Level.Discovered After Rigorous Review of Factors Affecting Instru

ML18113A640
Person / Time
Site:	Surry
Issue date:	11/20/1978
From:	Baucom T VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML18113A639	List: 05000280/LER-1978-035, Forwards LER 78-035/01T-0 05000280/LER-1978-035-01, /01T-0 on 781109:study of Calibr Techniques Showed That SI Accumulators Indicated Level Would Be Lower than Actual Level.Discovered After Rigorous Review of Factors Affecting Instru
References
LER-78-035-01T, LER-78-35-1T, NUDOCS 7811280238
Download: ML18113A640 (3)

LER-1978-035, /01T-0 on 781109:study of Calibr Techniques Showed That SI Accumulators Indicated Level Would Be Lower than Actual Level.Discovered After Rigorous Review of Factors Affecting Instru

Event date:
Report date:
2801978035R01 - NRC Website

text

NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION

{7.77)

LICENSEE EVENT REPORT.

CONTROL BLOCK: !-----'---'l'--__._l _..,___,__-c'I CD (PLEASE PRINT OR TYPE ALL REQUIRED INFORMATION) 6

~

I V I A 1

• s I p I s I 1 101 0 I O I - I O I O I O I O I O I -1 0 I O 101 41 1 I 1 I l I 1 101 I I 0 7

8 g

LICENSEE COOE 14 15 LICENSE NUMBER 25 26 LICENSE TYPE 30 57 CAT 58 CON'T CITTI 7

8

~~~~~~. ~JC~ I o I s I o I o I o I 2 I s I o 101 1 I 60 61 DOCKET NUMBER 68 69 1 I o I 2 I 1 I a I© I 1 I 1 I 2 I o I 1 I s 10 EVENT DATE 74 75 REPORT DATE 80 EVENT DESCRIPTION AND PROBABLE CONSEQUENCES@

!An engineering study of tank level instrument ca]ihration techniq11es demonstrated

~

I that the indicated level of SI Accumulators would be lower than actual level.

The

[:QID I condition is conservative for minimum level requirements but maximum 1 eve]_ 1 imi ts a.i=

((II] jT.S. 3.3 may be exceeded by 5.7 cu. ft. on Unit 1 and 8.0 cu. ft. on Unit 2.

Actual [QJI] !level differences are 0.7 inches on Unit 1 and 0.99 inches on Unit 2, Event is rPportd

[§J2] !able per T.S. 6.6.2.a.(2) and applies to Surry Unit Nos. 1 and 2.

CIT[]

7 8 9 SYSTEM CODE

CAUSE

CAUSE CODE SUBCODE COMP.

COMPONENT CODE SUBCODE VALVE SUBCODE 80

~

!I IB I@ ~@ Lu(9 lrlNlslT!R!ul@ Lu@ [LI@

7 8

9 10 Q

LER/RO CVENT YEAR

~

REPORT 17 l 8 I NUMBER 21 22 11 12 13 l==1 23 SEQUENTIAL REPORT NO.

I o I 3 I sJ 24 26 18 OCCURRENCE CODE I 01 1J 27 28 29 19 REPORT TYPE LU 30 20 l=1 31 ACTION FUTURE EFFECT SHUTDOWN

~ ATTACHMENT NPRD-4 FORM SUB.

PRIME C.OMP.

TAKEN ACTION ON PLANT METHOD HOURS ~ SUBMITTED

~@~@) ~@ Li t0 IO 1° 10 I ~@

33 34 35 36 31 40 41 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS @

~

42 SUPPLIER

~@

43 REVISION NO.

I._QJ 32 COMPONENT MANUFACTURER RI 3 j 6 I 9 I@

44 47 jThe condition was discovered by a rigorous review of factors affecting the instrument, DJJJ ji.e. calibration standard, b*oron concentration, pressure effects and temperature [I))] teff_ects.

The levels of the accumulators were brought into an operating band that is IJJJJ jconserv~tive for high and low volume requirements.

OJil 7

8 9

FACILITY STATUS

% POWER OTHER STATUS METHOD OF A

80 [QI]~@ 11 I O I OJ@l~_NA ____

DISCOVERY DISCOVERY DESCRIPTION ~

L.£J~~l~E_n~g=1.-*n_e_e_r_i_n~g"---S_t_u_d~y~~~~~~~~~--J 45 46 8

9 10 12 13 ACTIVITY CONTENT Q

RELEASED OF RELEASE AMOUNT OF ACTIVITY ITII1 LU@ ~@._I _____

NA ___

8 9

10 11 44 7

44 NA LOCATION OF RELEASE @

80 45 80 PERSONNEL EXPOSURES

~

t*UMBER r:;:;-. TYPE DESCRIPTION~

ITTIJ IO IO 10 J0LU@1--_NA _______________________

7 8

9 11 12 13 80 PERSONNEL INJURIES Q

NUMBER DESCRIPTION~

ITI~] IO IO 10 l@L--_N_A _____________________

~----J 7

8 9

11 12 LOSS OF OR DAMAGE TO FACILITY '43" TYPE

DESCRIPTION

~

[IE)~@

NA 80 7

8 9

10 PUBLICITY r::'\\

NRC USE ONLY ISSUED~ DESCRIPTION~

~

~e;L..-.. __

..:__NA _________________ __, I I I I I I I I I I I I I~

'all 1 ]. 2 § 0 ~ '

68 69 80 ;;;

NAME OF PHEPARER I* L Baucom PHONE: __

(8_0_4..;..)_3_5_7_-_3_1_8_!} ____ ~ J 80

Attachment, Surry Power Docket No:

Report No:

Event Date:

pag~* of 2)

Station, Unit 1 50-280 78-035/0lT-0 11-09-78 Safety Injection Accumulator Errors

1.

Description of Event

An engineering study of tank level instrument calibration techniques demonstrated that the indicated level in Safety Injection (SI) accumulators is lower than the actual level.

As a result, the maximum volume limits stated in Technical Specification 3.3 may have been exceeded but the minimum volume requirements have always been met.

In the worst case condition (maximum indicated level and 650 psia) the excess volume is 5.7 cubic feet (over 989) for Unit 1 and 8.0 cubic feet (over 1089) for Unit 2 *. These excess levels decrease the pressurized gas volume by no more than 1.15% in Unit 1 and 2.0% in Unit 2.

In actual level, the differences amount to 0.7 inches in Unit 1 accumulators and 0.99 inches in Unit 2 accumulators.

This event is reportable in accordance with Technical Specification 6.6.2.a.(2) and is applicable to Surry Units 1 and 2.

2.

Probable Consequences/Status of Redundant Systems:

The consequence of a higher-than-indicated level would be to reduce the volume of pressurized gas available to inject the accumulator contents.

Accident analyses are conducted based on minimum level and minimum pressure conditions.

Maximum levels are specified to assure that the accumulator contains sufficient pressurized gas to accomplish the injection.

In the worst case identified by the study, the maximum possible level reduced the gas *volume by 2% but this was at a condition of gas pressure 8% over minimum required pressure.

It is considered that even in "worst case" level error, the accumulator systems would have performed the intended function fully.

Therefore, the health and safety of the public were unaffected.

3.

Cause

The condition was discovered as the result of a rigorous review of the factors affecting the output of a differential pressure type liquid level indicator system.

The factors included in the study were calibra-tion standards. and techniques, boron concentrations, pressurized gas density variations, and variations in ambient temperature of the accumu~

lators.

4.

Immediate Corrective Action

The accumulator levels were lowered to the indicated levels recommended by the study on 11-9-78.

Attachment, Surry Power Docket No:

Report No:

Event Date:

• page 2 of 2 Station, Unit 1 50-280 78-035/0lT-0 11-9-78 Safety Injection Accumulator Errors

5.

Subsequent Corrective Action:

The station administrative documents for accumulator setpoints were changed on 11-15-78.

6.

Actions Taken to Prevent Recurrence:

Future level requirements for accumulator levels will be verified by the calculational methods outlined in the study.

7.

Generic Implications:

No other analagous situation is known to exist at Surry Power Station.