ML19353B189
| ML19353B189 | |
| Person / Time | |
|---|---|
| Site: | Summer  |
| Issue date: | 12/07/1989 |
| From: | Hayes J Office of Nuclear Reactor Regulation |
| To: | Bradham O SOUTH CAROLINA ELECTRIC & GAS CO. |
| References | |
| TAC-74826, NUDOCS 8912120143 | |
| Download: ML19353B189 (4) | |
Text
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i Dec mber 7, 1989 Docket No. 50-395 Mr. O. S. Bradham Vice President, Nuclear Operations South Carolina Electric & Gas Company Virgil C. Summer Nuclear Station P. O. Box 88 Jenkinsv111e, South Carolina 29065
Dear Mr. Bradham:
I
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION - RTD BYPASS MANIFOLD ELIMINATION AT V. C. SUMMER NUCLEAR STATION, UNIT NO. 1 (TAC HO. 74826)
By letter dated July 21, 1989, you requested a license amendment to modify the V. C. Summer Technical Specifications to support a modification to the RTD bypass system.
We have reviewed those areas of the V. C. Summer RTD bypass system submittal related to flow measurement uncertainty analysis, the review of affected accidents and the proposed technical ssecification changes. We have enclosed a request for additional information tlat needs to be addressed for our review to proceed.
Sincerely, Original Signed By:
John J. Hayes, Jr., Project Manager Project Directorate 11-1 Division of Reactor Projects - I/11 Office of Nuclear Reactor Regulation
Enclosure:
As stated cc w/ enc 1:
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Mr. O. S. Bracham South Carolina Electric & Gas Company Virgil C. Sumer Nuclear Station l
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Mr. William A. Williams, Jr.
Technical Assistant - Nuclear Operations i
Santee Cooper P. O. Box 764 (Mail Code 153)
Columbia, South Carolina 29218 J. B. Knotts, Jr., Esq.
Bishop. Cook, Purcell and Reynolds 1400 L Street, N.W.
Washington, D. C.
20005-3502 l
Resident inspector / Summer NPS c/o U.S. Nuclear Regulatory Commission Route 1, Box 64 Jenkinsville, South Carolina 29065 i
Regional Administrator, Region II i
U.S. Nuclear Regulatory Commission, 101 Marietta Street, N.W., Suite 2900 Atlanta, Georgia. 30323 Chairman, Fairfield County Council P. O. Box 293 Winnsboro, South Carolina 29180 Mr. Heyward G. Shealy, Chief l
Bureau of Radiological Health l
South Carolina Department of Health and Envirorimental Control 2600 Dull Street Columbia, South Carolina 29201 L
South Carolina Electric & Gas Company Mr. A. R. Koon, Jr., Manager Nuclear Licensing Virgil C. Summer Nuclear Station P. O. Box 88 Jenkinsville, South Carolina 29065 i
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ENCLOSURE V. C. SUMMER NUCLEAR STATION QUESTIONS ON RTD BYPASS SYSTEM REMOVAL 1.
Regarding the problem of the RTD response time identified in NUREG-0809 (Safety Evaluation Report, Review of Resistance Temperature Detector Time Response Characteristics, August 1981), describe (a) the method (s) for checking RTD response time after installation, (b) the frequency of checks and (c) the safety allowance or other methods to provice assurance that the response times do not drift outside acceptable limits between the required 18-month checks.
2.
The calibration of the RTDs is performed before the calorimetric heat balance at each refueling.
It is understood that this is by a cross calibration method in which it is assumed that variation occurs in a random manner from the original calibration from the manufacturer.
Therefore, the nean value is assumed to be the correct value. However, over a 40-year life, the RTDs may drift in one direction. One manufacturer has indicated a 1 deg F drif t in five years, it is noted that some references indicate that although platinum RTDs are quite stable, there is evidence of drif t (NUREG-0809 in Question 1 and NUREG/CR-4928, Degradation of Nuclear Plant Temperature Sensors, June 1987). How is the original calibration accuracy of the RTD established?
How will you be able to tell if there is unacceptable drif t in one direction and what steps will be then taken?
3.
Your new method of obtaining the hot leg temperature differs from the previous method.
In the previous method, the flow in each hot leg was sampled from tne scoops in the pipe cross section.
This sampled flow was measured in a mixing plenum to obtain an average temperature value.
Your present method replaces the sampled flow from a scoop with a single temperature measurement of the scoop flow which is used to be equivalent to the former sampled flow value. Please indicate how you plan to check and confirm the accuracy of this new hot leg average temperature measurement method (new system) against the former RTD bypass system method (old system).
Identify the acceptance criteria to be used in the confirmation.
4 In WCAP-12189, you have discussed the method for detecting failed RTDs which may go off-scale or fail gradually. What is the amount of temperature deviation in degrees that will cause T-avg and delta T alarms? What is the frequency of channel checks?
5.
You have provided the results of a RCS Flow Calorimetric uncertainty and have indicated that this value is proprietary.
However, to use this value it must be in the plant Technical Specifications in a section addressing F-delta-H or a section pertaining to DNB parameters.
In addition, it is a staff position that a 0.1% venturi fouling penalty should be added.
A oiscussion should be provided in the appropriate bases section of the Technical Specifications to indicate that a penalty is aoded for undetected fouling and the action to be taken before performing subsequent precision heat balance measurements, 1.
e., either quantifying the effect of fouling and compensating in the RCS flow rate measurement or cleaning the venturi to eliminate the fouling.
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d DISTRIBUTION Doo6st444e$
NRC PDR L
Local FDR S. Yarga 14-E-4 3
G. Lainas 14-H-3 E. Adensam 14-B-20 P. Anderson 14-B-20 J. Hayes 14-B-20 OGC 15-B-18 E. Jordan MNBB-3302 l
ACRS(10)
P-315 Summer File b
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