ML20086M546

Responds to NRC 910501 Request & Supplements 910206 Util Ltr Re Instrument Setpoints.Util Engineering Std ES-002, Instrument Error Calculation & ..., Is Based on Guidance of ISA-S67.04 Not ISA-RP67.04, Methodologies For..

ML20086M546
Person / Time
Site:	Oyster Creek
Issue date:	12/06/1991
From:	Devine J GENERAL PUBLIC UTILITIES CORP.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
5000-91-2086, C321-91-2283, NUDOCS 9112170515
Download: ML20086M546 (4)

Text

f a

• ENuclear

%""n-2 t-~

Paratpany, New Jersey 07054 201 310 7000 TELEX 136 482 Wnters Drect Dial Nu%e, December 6, 1991 5000-91-2086 C321-91-2283 U. S. Nuclear Regulatory Commission Attention:

Document Control Desk Washington, D.C.

20555 Gentlemen:

Subject:

Oyster Creek Nuclear Generating Station Facility License No. DPR-16 Docket No. 50 219 l

Response to Request for Additional Information 1

Instrument Setpoints This letter is provided in response to a NRC staff request for additional information dated May 1,1991 and supplements GPU Nuclear (GPUN) letter dated February 6, 1991. Each staff information request item is reiterated and GPUN's response follows:

Item-1

' Describe the basis for the GPU Nuclear Corporation's (GPUN) engineering standard ES 002,

" Instrument Error Calculation and Setpoint Determinatiort. " Are the guidelines of ISA-RP67.04, Section 7, "Setpoint Relationships," considered?'

fluponse 1 GPUN Engineering Standard ES-002 is based on the requirements of ISA-S67.04 (1982).

ISA-P,P67.04, " Methodologies for the Determination of Setpoints for Nuclear Safety-Related Instrumentation," has not been formally issued. We are familiar with this document and will-consider its application to the degree practical and appropriate when it is issued.

Item 2

'In regard to GPUN Calculation Cl302-640-5350-001, "0yster Creek Technical Specification Instrument Drift Calculations, Revision 1,

what drif t factors were considered?

a.

Has the seismic event effect on the setpoint been considered for RE02, RE18, and RE23; has the seismic event effect on the process instrumentation been considered for RE02 and RE237 4n (

y m 7o313 911206 r

p mcx exy

, g g

aeumo,ce,ne,em,m - -om - u-coe~

1

)

I e

~

5000-91-2086 C321-91-2283 Page 2 b.

What is the effect of process instrument drift, calibration tolerances, calibration equipment tolerances, and reference leg (if any) density effects for RE02, and RE23?

What is the effect of calibration tolerances and calibration equipment tolerances for RE187 c.

For RE02, RElD, and RE23, show the process effects, process instrumentation drift effects, environmental effects, loop loading, talibration equipment uncert ainties, and "as-lef t" tolerances, etc.,

have beer included in the setpoint methodology calculations.'

Response _2-Historical drift is established in GPUN calculation Cl302-640-5350-001.

This is 95/95% confidence drift-based on actual instrument performance over time. No specific drift effects are considered in this calculation.

a.

The seismic event effect on the setpoint was not considered for

RE02, RE18, and RE23.

Seismic event effect on process instrumentation is not considered enveloped by historical drift.

The~ instruments are qualified to maintain integrity and remain function 1 during and after a seismic event.

b.

Historical drift envelopes the effect of process instrument drift.

Calibration tolerances, calibration equipment tol erances, -- - or reference leg density effects are-not considered enveloped by historical drift.

c.

GPUN Engineering Standard ES-002 describes the method and format for setpoint calculations.

This standard _' describes the factors af fecting instrument accuracy along with methods for calculating their impact on overall loop accuracy, and setpoint.

Detailed requirements for the instrument setpoint relationships include process

effects, process.

instrumentation drift

effects, environmental effects, calibration equipment uncertainties, and as-left tolerances.

GPUN has performed loop error calculations, in accordance with ES 002 for RE02, RE18, and RE23 instrument loops.

A loop loading effect evaluation is normally performed during the initial l

design and installation of a process instrument loop. Further evaluations will be performed during subsequent modifications to the loop, loop loading effect is not considered as part of the setpoint calculation.

L L

I

--..m

a

• 5000-91-2036 C321-91-2283 Page 3 Item 3 I

'What is the margin between the allowable value for RE02, RE18, and RE23 and the respective safety (operation) limits?'

i Reinnoin.1 GPUN Engineering Standard ES-002 describes the " Technical Specification Limit" as the " Operational Allowable Value". The allowable value, normal operating limit, and instrument range for RE02, RE18, and RE23 are given i

below:

i Allowable Value Normal (Tech. Spec.

Operational Instrument Jn11rument Limilj Limit Rarse RE02 186 inch TAF 160 inch 1AF 85 185 Inch TAF RE18 156 Inch TAF 160 Inch TAf 189 Inch TAF RE23-1825 PSIG 940 PSIG S0 1173 PSIG

• TAF - Top of active fuel Item 4

'For the above instrumentation, address the process instrumentation signal shift betwaen cold - calibration conditions and normal operation environmentt.,

including abnormal-environments when the setpoint is required to operate.'

-ER129Ed !

RE02 and RE18 are differential pressure instruments for level raeasurement and are calibrated during normal operation of the plant, i.e., during hot conditions.

RE23 is a pressure

switch, and as such,.procest instrumentation signal shift is not a concern.

Item 5

'For historic drift greater than calculated drift, and above the technical specification limit, the analysis presented for justification assumes that the transient is sufficiently rapid to-render the setpoint error insignificant, However, the Technical Specification is-still not sat'sfied, nor is the response time of instrumentation-discussed.

The analysis presented appears to be engineering judgement. Were calculations performed, and was the safety ar,alysis reviewed?'

Resoonse_5

+

Thn justification for the RE18s was based on a review of the safety

[

analysis for small break 1.0CA and engineering judgement on the rate of decrease of water level.

Calculations were not performed.

h

,+

m-

.,,---._-----,._..m.--_

...c..

l

• 5000-91-2086 C321 91-2283 Page 4 1 tem 6

'In Reference 3, the instrument surveillance intervals are being changed I

froin quarterly to yearly. For Group 1 loops 1, 3, 4, 9 and 10 are the as left and as found historical drift values still valid for that new and extended interval?'

RPJponse 6 Group 1 loop 1 (RE03), loop 3 (RE0S and HE05/19), and it op 4 (RE02) uttitre Rosemount transmitters and foxboro electronics, ihe stability (drift)specificationforRosemounttransmitterswasdeteminedasvalid for 30 months (Rosemount test report 08900126 revision a).

The drift value for foxboro electronics is negligible. The as found limits for the loops are unaffected due to the surveillence interval change. There will be no change in the historical delft values.

Group 1 loop 9 (RD86) and loop 10 (RD90) utilize Gould transmitters and Foxboro electronics.

The drift value for Fcuboro electronics is negligible. - Existing setpoint calculations for both loops were revised to take into account added drift due to the change in surveillance interval, it was concluded that existing as found limits remain unchanged.

Historical drift values are based on as found data.

Very ti y)urs, i

GdA J. C. OeVine, Jr.

l Vice President and Director l

Technical Functions JCD/PFC/amk cc: Administrator, Region !

l NRC Oyster Creek Project Manager NRC Resident Inspector-