ML20054G486
| ML20054G486 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 06/15/1982 |
| From: | Sinclair J VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | Vassallo D Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737, TASK-2.F.1, TASK-TM FVY-82-69, NUDOCS 8206210601 | |
| Download: ML20054G486 (6) | |
Text
1 i.
VERMONT YAN KEE NUCLEAR POWER CORPORATION SEVENTY SEVEN GROVE STREET 2.C.2.1 ItUTLAND, VERMONT 05701 FVY 82-69 REPLY 70:
ENGINEERING OFFICE 1671 WORCESTER ROAD FRAMINGH AM, M ASSACH USETTS 01701 TELEPHONE 617 872-8100 June 15, 1982 United States Nuclear Regulatory Commission Washington, D. C. 20555 Attention:
Office of Nuclear Reactor Regulation Mr. Domenic B. Vassa]Io, Chief Operating Reactors Branch #2 Division of Licensing
References:
(a) License No. DPR-28 (Docket No. 50-271)
(b) Letter, USNRC to VYNPC, dated May 14, 1982
Subject:
NUREG-0737, Items II.F.1.4, II.F.1.5, and II.F.1.6
Dear Sir:
Reference (b) requested Vermont Yankee to review and confirm our responses to questions related to NUREG-0737, Items II.F.1.4, " Containment Pressure Monitor," II.F.1.5, " Containment Water Level Monitor," and II.F.1.6,
" Containment Hydrogen Monitor." These questions were originally addressed in a telecon on March 26, 1982. The requested confirmation and additional clarification is provided as an attachment to this letter.
We trust that this information is satisfactory; however, should you have any questions, please do not hesitate to contact us.
Very truly yours, l
VERMONT YANKEE NUCLEAR POWER CORPORATION ib.
bttd J. B. Sinclair Licensing Engineer O
JBS: dad I
Attachments I
I 8206210601 820615 PDR ADOCK 05000271 P
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ENCLOSURE 1 Question 1: The review we are discussing is the Containment Systems Branch (CSB) part of the total review discussed in NUREG-0737.
The CSB review consists of all items discussed under " Position" and
" Clarification" except the review of compliance to the Appendix B criteria, and the review of the measurement system compirtion dates.*
- In the submittals we received to date, you have not indicated that you plan to take exception to any of the NUREG-0737 criteria in our area of review. Are you planning any exceptions in our area of review of which we are not aware?
Answer 1:
No.
Question 2: What is the accuracy of your pressure monitor? State this for both the indicator and the recorder.
Answer 2:
The pressure monitor has readouts on both an indicator and rec o rd er.
Transmitter SD'= 0.25%
Indicator SD = 1.5%
Recorder SD = 0.5%
Indicator System SD = RSS (0.25%, 1.5%) = 1.52%
Recorder System SD = RSS (0.25%, 0.5%) = 0.56%
where SD is the standard deviation of errors and RSS is the root sum square.
Vermont Yankee Clarification:
1.
The transmitter installed to measure drywell pressure is a Rosemount Model 1153B. The manufacturer states in his product description that the accuracy for zero-based sgans at j
reference conditions is +p.25% of calibrated span, including I
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the combined effects of linearity, hysteresis and repeatability. The manufacturer has stated verbally that this represents a 100% confidence level.
2.
The indicator installed is a Sigma Model W-1251.
The manufacturer states in his product description that the accuracy of this indicator is +1.5% of full-scale value.
Further, the repeatability is +2% of full-scale value. The manufacturer has stated verbally that this accuracy represents 100% confidence factor. From our understanding of the terms accuracy and repeatability, it appears that use of the repeatability value would be more appropriate in this case since the accuracy is a matter of periodic calibration and the repeatability will govern the variation between successive readings. Note also that use of repeatability in this case is more conservative.
3.
The recorder installed is a Leeds and Northrup Speedomax M Mark III. The manufacturer states in his operator's manual that the accuracy of this recorder is +0.5% of full-scale value. The manufacturer has stated verbally that this represents a 100% confidence level, and includes repeatability.
4.
We concur that the use of the root sum square method is appropriate to calculate the loop accuracy for both the indicator loop and the recorder loop.
Based upon the accuracies given above, we calculate these loop accuracies as follows:
(0.25%) + (2.0%)2 Indicator (3SD)
=
= 4.06 3SD
= 2.02%
(0.25%) + (0.5%)
Recorder (3SD)
=
= 0.31 3SD
= 0.56% _ _ - ___ __.
Question 3: What is the time response of your pressure monitor? State this for both the indicator and the recorder.
Answer 3:
Transmitter TC = 0.2 sec.
Indicator Sweeps Full Scale inj2.5 sec.
TC = 2.5/4 = 0.63 sec.
Recorder Sweeps Full Scale in 1 sec. 63% of scale in 0.63 sec.-
Indicator System TC = TC (HP-67) = 0.9 sec.
Vermont Yankee Clarification:
1.
The transmitter manufacturer states in his product description that the fixed response time (63%) at 100 F for these transmitters is 0.2 seconds.
2.
The indicator manufacturer states in his product description that the response time is 2.5 seconds maximum. We utiderstand this to mean 2.5 seconds to full scale (100%).
This would give the equivalent time constant (63%) as 2.5/5 = 0.5 seconds.
It is our understanding that "for a step change, the output is defined as reaching its final value after five time constants".
3.
The recorder manufacturer states in his operator's manual that the span-step time response time is less than one second, and that pen movement may generally be considered linear with respect to time.
4.
The referenced letter states that the indicator system time constant is 0.9 seconds and that this was calculated by using an NP.C developed calculator program.
Since we have not seen l
this program, we are not able to comment on the result obtained.
Question 4: What is the accuracy of your water level monitor? State this for both the wide-range instrument and the narrow-range instrument.,
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Answer 4:
Water level monitor is in torus only. Readout is on both indicator and recorder. Uncertainties are as follows:
Transmitter SD = 0.25%
Indicator SD = 1.5%
Rec order SD = 0.5%
Indicator System SD = RSS (0.25%, 1.5%) = 1.52%
Recorder System SD = RSS (0.25%, 0.5%) = 0.56%
Vermont Yankee Clarification:
The torus water level monitors utilize the same types of equipment as the drywell pressure monitors. The clarifications stated previously under pressure monitors apply here also.
Question 5: Where are the hydrogen sample ports placed?
Answer 5:
There are three sample ports in the drywell of the following locations:
(1) top of drywell, (2) halfway up vessel in drywell, and (3) at bottom of vessel on drywell.
There is one sample port in the top quadrant of the torus l
available through two separate paths.
l Question 6:
Is there any obstruction which would prevent hydrogen, escaping from the core, from reaching the hydrogen sample ports quickly?
Answer 6:
No.
t l
l Question 7:
What is the accuracy of your hydrogen monitor?
l r
Answer 7:
The hydrogen analyzers have readouts on both an indicator and a recorder.
The analyzers come as a unit which consists of an analyzer unit, a linearizer, an amplifier and an indicator.
These units have a SD = 2.5%.
The recorders beinE added have an SD = 0.5%.
Assuming that the built-in indicator has an SD = 1.0%, we have Recorder System SD = 2.5% - 1.0%2 + 0.5%2 = 5.50.
Recorder System SD = 2.35 Vermont Yankee Clarification:
1.
The hydrogen monitors being installed are Teledyne Analytical Instruments.
The manufacturer states in his product description that the accuracy of these units is +2.5% of full scale (dry basis).
The manufacturer has stated verbally that this represents a 100% confidence level, and that the effect of the indicator on this
re is negligible.
2.
The recorder being used is the same type utilized in the pressure and level monitors, and therefore the same clarifications apply in this instance.
3.
Based upon the accuracies given above, we calculate the recorder loop accuracy as:
(3SD)
= (2.5%)2 + (0.5%)
= 6.50 3SD = 2.55%
Notes:
1.
Curtis D. Johnson, Process Control Instrumentation Technology, John Wiley and Sons, 1977.