ML20070Q853

Forwards Instrumentation Error Analysis of Reactor Vessel Water Level Indication Sys,Completing Response to NRC 820619 Request for Info

ML20070Q853
Person / Time
Site:	Point Beach
Issue date:	01/19/1983
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	Clark R, Harold Denton Office of Nuclear Reactor Regulation
References
NUDOCS 8301270184
Download: ML20070Q853 (10)

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El W POWER COMPANY 231 W. MICHIGAN, P.O. BOX 2046, MILWAUKEE, WI 53201 January 19, 1983 Mr. H. R. Denton, Director

' Office of Nuclear Reactor Regulation U. S. NUCLEAR REGULATORY COMMISSION Washington, D. C. 20555 Attention: Mr. R. A. Clark, Chief Operating Reactors Branch 3 Gentlemen:

DOCKET NOS. 50-266 AND 50-301 INSTRUMENTATION ERROR ANALYSIS REACTOR VESSEL WATER LEVEL INDICATION SYSTEM POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 Enclosed with this letter is an instrumentation error analysis of the Reactor Vessel Water Level Indication System for the Point Beach Nuclear Plant, Units 1 and 2. The error analysis of the instrumentation completes our response to your request for information dated June 19, 1982. The majority of the information requested in that June'19 letter was provided with'our letter dated July 28, 1982.. Please contact us if you have any additional questions regarding this information.

Very truly yours, l$ho P

O k Vice President-Nuclear Power C. W. Fay Enclosure Copy to NRC Resident Inspector J

INSTRUMENTATION ERROR ANALYSIS REACTOR VESSEL ~ WATER LEVEL-INDICATON SYSTEM POINT BEACH NUCLEAR PLANT f

f The Reactor Vessel Water Level Indic'ation System at the Point Beach Nuclear Plant is a differential pressure system utilizing Foxboro pressure transmitters, both' differential-and gauge, located inside containment. Thermo-couples mounted on the vertical portions of the tubing connecting the top and bottom of the reactor. vessel to the differential' pre'ssure transmitters are used -

to~ measure the tubing temperature and prov'ideicompens'ation for differing water

, densities external to the vessel. The reactor vessel incore thermocouples are

-used to measure the wat r-temperature inside the vessel. A function generator I is-use'd to compute the water density inside the. reactor vessel based on this I. ' water temperature. Steam density inside the reactor vessel is computed by a function generator using reactor coolant system pressure as an input. Incore and tubing; thermocouple signals are processed by a computer multiplexer and a provided as inputs to the analog electronics. The transmitter signal condition-

)

ing and water level computation is performed in Foxboro-SPEC 200 analog elec-

, .tronic modules.

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l This instrumentation error analysis was performed'by assuming a refer-ence set lof nominal accident conditions, perturbing each signal a small amount I

from its reference value,-and then computing the effect of that perturbation on.

j- the output. All individual errors except the radiation effects on the transmit-ters were assumed to be independent of each other and to have an equal chance of l-being positive or negative. The error values listed are maximum values.

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Except for the transmitter radiation effects, the errors were combined using the square root of the sum of the squares method. Since the radiation induced transmitter l

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_ . _ _ . _ _ _ . _ _ _ _ _ _ .. ,_......._._.. _ .._._ _ _ _ ._. .. ~

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INSTRUMENTATION ERROR ANALYSIS REACTOR VESSEL WATER LEVEL INDICATION SYSTEM POINT BEACH NUCLEAR PLANT January 1983

(

I errors were all in the same drection' where applicable, radiation errors were

. combined algebraically..

Two accident co'nditions are tabulated. In the first case it is assumed that a small-break loss-of-coolant-accident (LOCA) or a steam line break (SLB) has caused a steam bubble to form'in'the reactor-vessel but the core is

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not uncovered or degraded. The containment. temperature, pressure and spray flow

- are_ fluctuating. There is no significant containment radiation exposure to the

- transmitters in this case.

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In the second case.it is' assumed that an inadequate core cooling (ICC) i accident has occurred and the core has suffered severe damage with a large f I l radiation release to the containment. The core has been recovered by coolant

( but the vessel is not full. The transmitters have received a significant radia-tion exposure. The containment temperature and pressure are abnormal but are not rapidly changing. There is no contairaant spray flow.

.The' key element in this1 instrumentation error analysis is the response of the Foxboro transmitters to the containment environment resulting from the 1

accident conditions. An environmental testing program which included Foxboro transmitters was sponsored by a Utility Transmitter Qualification Group and performed by Wyle Labs. Because the enivronmental testing was set up to enve-L

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lop ~the worst case LOCA and SLB conditions at many plants, the test parameters were more severe than would result from the assumed accident cases if they L occurred at the Point Beach Nuclear Plant. The listed errors were the maximum l

errors found after the first two minutes of the environmental testing. It was assumed that the water level indication would not be utilized until after two

.g.

. . ._ - _. . _ _ - ~_ _ .___ - . _ . _ _ _ _ . - _ _ . _ _ . . _ , _ . _

minutes into a severe accident. The transmitter errors were excerpted from a draft of W'le y Qualification Report No. 45592-2.

For the first case, the maximum transmitter error due to the LOCA/SLB environmental effects from the temperature, pressure, and spray profiles was 4.6%. This 4.6% transmitter error, combined with other instrumentation errors, resulted in a total indication error of 2.6 ft. This is listed in the table as a transient error. After the rapidly changing portion of the environmental profile was over, the maximum transmitter error due to environmental effects i

decreased to 2%, for a total indication error ~ of 1.5 ft. This is listed in the l table as a steady state error. The sign of these errors could be either posi-tive or negative.

4 In the second case the major portion of the transmitter error was the error due to radiation exposure. This component of the error was always such that the transmitter current output was less than nominal. The value chosen from the test data for this error analysis was -5.5%, which was the maximum j value obtained during the radiation testing up through 70 megarads. This inte-grated dose is equivalent to approximately one week exposure at worst case conditions. The system indication errors due to radiation exposure of the l

transmitters were added algebraically to each other. The maximum steady state 1

transmitter error due to environmental effects of 2% was used in the analysis.

The results are that the indication error due to the assumed ICC event was

-2.55 ft. i 1.5 ft. A positive system error implies that the control room l

l indicator indicates a higher water level in the reactor vessel than actually l exits. Negative error therefore results in an indicated level that is lower tnan actual level.

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. 4 ERROR ANALYSIS TABLE CASE 1 CASE 2 SMALL LOCA OR SLB AFTER ICC EVENT DESCRIPTION OF ERROR SOURCE SOURCE INDICATION SOURCE INDICATION ERROR ERROR ERROR ERROR

1. Narrow Range Differential Pressure Transmitter .

The error values listed are

% of span.

a. Calibration 0.5% 0.25 ft. 0.5% 0.25 ft.

Includes linearity and hysteresis,

b. Instrumentation 0.25% 0.13 ft. 0.25% 0.13 ft.

Instruments used to calibrate .

transmitter.

c. Static Pressure Effect 0.5% .0.25 f t. 0.5% 0.25 f t.

d. Drift 0.5% 0.25 ft. 0.5% 0.25 ft.

One year

e. Offset 0.5% 0.25 ft. 0.5% 0.25 ft.

Due to long term operation in saturation

f. Hydraulic Effects 1.0% 0.5 ft. 1.0% 0.5 ft.

Includes effects of fluid flow past taps l g. Envircomental Effects 4.6% 2.26 ft. 2.0% 0.98 ft.

! Temperature, pressure and spray i h. Radiation Effects 0.0% 0.0 ft. -5.5% -2.70 ft.

l f

I 2. Wide Range RCS Pressure Transmitter The error values listed are %

of span.-

i l a. Calibration 0.5% 0.01 ft. '0.5% 0.01 ft.

l Includes linearity and hysterisis.

l L _

.- 1 l

ERROR ANALYSIS TABLE l l

CASE 1 CASE 2 F

SitALL LOCA OR SLB AFTER ICC EVENT RR0 SOU E SOURCE INDICATION SOURCE INDICATION ERROR ERROR ERROR ERROR

b. Instrumentation 0.25% 0.01 ft. 0.25% 0.01 ft.

Instruments used to calibrate '

transmitter

c. Drift 0.5% 0.01 ft. 0.5% 0.01 ft.

One year

d. Hydraulic Effects 1.0% 0.0 3 f t. 1.0% 0.03 ft.

Includes effects of fluid flow past taps

'e. Environmental Effects 4.6% 0.13 f t. 2.0% 0.06 ft.

Temperature, pressure and spray. The offset effect of containment pressure on ,

this. gauge transmitter is included.

f. Radiation Effects 0.0% 0.0 ft. -5.5% +0.15 ft ,

.)

3. Incore Thermocouples

a. Accuracy of average 1F 0.04 ft. 1"F 0.04 ft.

thermocouple indication

b. Error in average representa- 5F- 0.19 ft. .5 F 0.19 ft.

tion due to thermal gradients in vessel.

4. - Fluid Line Thermocouples

a. Thermocouple Accuracy 2*F 0.10 ft. 2F 0.10 ft.

b. Error in representation due 10 F 0.52 ft. 5'F. 0.26 ft.

to thermal gradients along line

5. Control Room Indicator The error values listed are %

of span.

= _ _

ERROR ANALYSIS TABLE CASE 1 CASE 2 DESCRIPTION OF SMALL LOCA OR SLB AFTER ICC EVENT ERROR SOURCE SOURCE INDICATION -

SOURCE INDICATION ERROR ERROR ERROR ERROR

a. Calibration 0.5% 0.18 ft. 0.5% 0.18 ft.

Includes linearity and hysteresis

b. Drift 0.5% 0.18 ft. 0.5% 0.18 f t.

One year

'c. Resolution 0.5% 0.18 ft. 0.5% 0.18 ft.

The error values listed for the Foxboro SPEC 200 modules are % of output span

6. Input Amplifier for Tubing Static--

Head from Cocputer Multiplexer

a. Calibration 0.5% 0.08 ft. 0.5% 0.08 ft.

b.. Drift 0.5% 0.08 ft. 0.5% 0.08 ft.

One year

7. Input Amplifier for. Avg.~Incore Temperature from Computer Multiplexer

a. Calibration 0.5% 0.13 ft. 0.5% 0.13 ft.

b. Drift 0.5% 0.13 ft. 0.5% 0.13 ft.

One year

8. Function Generator computes water density from temperature

a. Calibration 0.5% 0.08 ft. 0.5% 0.08 ft.

b. Drift 0.5% 0.08 ft. 0.5% 0.08 ft.

One year

c. Accuracy of Curve Fit 1.0% 0.15 ft. 1.0% 0.15 ft.

ERROR ANALYSIS TABLE CASE 1 CASE 2 DESCR1PTION OF SliALL LOCA OR SLB AFTER ICC EVENT ERROR SOURCE SOURCE INDICATION SOURCE INDICATION ERROR ERROR ERROR ERROR

9. Function Generator computes steam density from pressure

a. Calibration 0.5% 0.02 ft. 0.5% 0.02 ft.

b. Drift 0.5% 0.02 ft. 0.5% 0.02 ft.

One year

c. Accuracy of Curve Fit 1.0% 0.04 ft. 1.0% 0.04 ft.

10. Summer used to compute numerator

a. Calibration 0.5% 0.38 ft. 0.5% 0.38 ft.

b. Drift 0.5% 0.38 ft. 0.5% 0.38 ft.

One year

11. Summer used to compute denominator

a. Calibration 0.5% 0.15 ft. 0.5% 0.15 ft.

b. Drift 0.5% 0.15 ft. 0.5% 0.15 f t.

One year

12. Divider

a. Calibration 0.5% 0.18 f t. 0.5% 0.18 ft.

b. Drif t 0.5% 0.18 ft. 0.5% 0.18 ft.

One year

13. Output Isolation Amplifier

a. Calibration 0.5% 0.18 ft. 0.5% 0.18 ft.

b. Drift- 0.5% 0.18 ft. 0.5% 0.18 ft.

One year ERROR ANALYSIS TABLE' SUPNARY

, . CASEil CASE 2 SMALL LOCA OR SLB- AFTER ICC EVENT INDICATION ERROR INDICATION ERROR TOTAL SYSTEM ERROR 1 2.6 ft. (Transient) -2.55 1 1.5 ft.

1 1.5 ft. (Steady State) i

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