ML20215L687
| ML20215L687 | |
| Person / Time | |
|---|---|
| Site: | Brunswick  |
| Issue date: | 05/01/1987 |
| From: | Cutter A CAROLINA POWER & LIGHT CO. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| Shared Package | |
| ML20215L691 | List: |
| References | |
| NLS-87-023, NLS-87-23, NUDOCS 8705120329 | |
| Download: ML20215L687 (3) | |
Text
-.-
y C9&L Carolina Power & Light Company.
MAY 1 1987.
SERIAL: NLS-87-023 10CFR50.90 87TSB01' United States Nuclear. Regulatory Co'mmission ATTENTION: Document Control Desk Washington, DC, 20555 BRUNSWICK STEAM ELECTRIC PLANT, UNIT NOS.1 AND 2 DOCKET NOS. 50-325 & 50-324/ LICENSE NOS. DPR-71 & DPR-62 REOUEST FOR LICENSE AMENDMENT ROSEMOUNT ANALOG TRIP SYSTEMS
. Gentlemen:
SUMMARY
In accordance with the Code of Federal Regulations, Title 10, Parts 50.90 and 2.101, Carolina Power & Light Company (CP&L) hereby requests a revision to the Technical
- Specifications (TS) for the Brunswick Steam Electric Plant (BSEP), Unit Nos. I and 2.
The proposed revisions incorporate test frequency changes for the Rosemount Analog Trip Unit Systems.. The frequency of functional and calibration tests is being changed from monthly to semiannually.
DISCUSSION During the period from 1981 to 1984 = the direct pressure and differential pressure switches that provide the input intelligence to safety system log (ic for the Reactor Protection S stem (RPS), Nuclear Steam Supply Shutoff System NSSSS) and Emergency Core Coolin System (ECCS) were replaced with Rosemount transmitters and the Rosemount nalog Trip stem. These changes were based on the General Electric Company (GE) Licensing opical Report NEDO-21617-A, " Analog Transmitter / Trip Unit
' System for Engineered Sa eguard Sensor Trip Inputs," issued in late 1978 as an approved method for improving safety system instrumentation.
Observations made by both maintenance and operating personnel during the past five years of operation of the Rosemount Analog Trip System have indicated that the system
.has a very low failure rate and requires little, if any, calibration. A study of drift and failure rates of these instruments indicates that a test interval of six months could be used while maintaining an exceptional availability of 0.9999. The overall system test interval is determined based on the sum of the non-annunciated failure rates of the trip
-units and trip relays. The results of the study are included in Enclosure 3, and an -
independent review by Energy Incorporated entitled " Review of the Rosemount Analog Trip Unit Justification for Test Interval Frequency Change" is included in Enclosure 4.
Based on this demonstrated reliability and stability of the Rosemount Analog Trip System, it becomes apparent that the current monthly testing required by TS and established by NEDO-21617-A is unnecessary and contributes adversely to the following i
areas related to safety:
l.
A large number of half scrams are taken for testing (288/ year),
2.'
A large number of half group isolations are taken for testing (912/ year),
3.
Out of service time for safety systems such as HPCI and RCIC are increased I
[.
because the systems are isolated during testing (192/ year),
L h
p 4gge 8705120329 870501 m
Apock 0500o324 g ql
[
A
- p pg et
- P. O. Box 1551
- Niesgn N C. 27602 h,.
a
~ DocumGnt Control Desk
- NLS-87-023 / Page 2 '
MAY 1 1987
~
4.
Increased stroking of valves in the drywell is required for testing which may result in increased drywell leakage and potential valve failures, 5.
High frequency testing creates a higher potential for personnel error.
Rosemount Analog Trip System stability over the past five years supports an increase in test' interval. Of 6177 calibrations,96 percent of the sampled surveillance test results fell within the manufacturers trip point repeatability specifications. In fact, approximately 2400 showed absolutely no drift in setpoint values. The trip units, over their operating history, have exhibited a slight drift in and around their setpoint, however have stayed well within the manufacturer's specifications.
Increasing the present monthly surveillance interval to a six-month test interval would provide the following:
1.-
Exceptional system availability of 0.9999 with simultaneous testing, i
2.
A reduction in number of half scrams taken for testing (reduced from 288/ year to 48/ year),
3.
A reduction in number of half group isolations taken for testing (reduced from 912/ year to 152/ year),
4.
Reduction of out of service time for safety systems (isolation reduced from 192/ year to 32/ year),
5.
Decreased stroking of valves in the drywell, 6.
Less potential for personnel error during testing.
SIGNIFICANT HAZARDS ANALYSIS The Commission has provided standards in 10CFR50.92(c) for determining whether a significant hazards consideration exists. A proposed amendment to an operating license for a facility involves no significant hazards consideration if operation of the facility in accordance with the proposed amendment would not: (1) involve a significant increase in the probability or consequences of an accident previously evaluated,(2) create the possibility of a new or different kind of accident from any accident previously evaluated, or (3) involve a significant reduction in a margin of safety. Carolina Power & Light Company has reviewed this request and determined that:
1.
The proposed amendment does not involve a significant increase in the probability or consequences of an accident previously evaluated. The proposed surveillance frequency change will not decrease the Rosemount Analog Trip Unit System availability below the.999 specified in the GE Topical Report NEDO-21617-A. The study of the drif t and failure rates of the Rosemount Analog Trip Units System in use at BSEP indicates that the trip points are highly repeatable and it has a much lower actual failure rate than assurred in NEDO-2l617-A, which provided the basis for monthly surveillance. The study shows that a test interval of six months could be used, while maintaining an exceptional availability of 0.9999. Increasing the surveillance interval would reduce the number of half scrams and half group isolations required for testing, reduce out of service time for safety systems, decrease potential drywell leakage and potential valve failures by stroking
E i'
Docun.ent Control Desk NLS-87-023 / Page 3 MAY 1 1987 valves inside the drywell less of ten, and reduce the potential for personnel error. A net reduction in risk (gain in safety) would be realized with the increased interval.
2.
The proposed amendment does not create the possibility of a new or different kind of accident from any accident previously evaluated. As stated above, availability would remain within the guidelines established by GE. There is no possibility of a new or different kind of accident.
3.
The proposed amendment does not involve a significant reduction in the margin of safety. In fact, it involves a net increase in the margin of safety by providing a reduction in half scrams, half group isolations, out of service time for safety systems, drywell leakage and potential valve failures, and personnel errcr.
Based on the above reasoning, CP&L has determined that the proposed changes involve ro significant hazards consideration.
ADMINISTRATIVE INFORMATION The revised BSEP Technical Specification pages are provided in Enclosures 1 and 2. The Company has evaluated this request in accordance with the provisions of 10 CFR 170.12 and determined that a license amendment application fee is required. A check for $150 is enclosed in payment of this fee.
Please refer any questions regarding this submittal to Mr. Sherwood R. Zimmerman at (919) 836-6242.
You ery tru,
f. l /() y
/
A. B. Cutter - Vice Preshent Nuclear Engineering & Licensing ABC/ BAT /BMC (5124 BAT)
Enclosures cc:
Dr. J. Nelson Grace (NRC-Ril)
Mr. W. H. Ruland (NRC-BNP)
Mr. E. Sylvester (NRC)
Mr. Dayne H. Brown A. B. Cutter, having been first duly sworn, did depose and say that the information contained herein is true and correct to the best of his information, knowledge and belief; and the sources of his information are of ficers, employees, contractors, and agents of Carolina Power & Light Company.
du-os, w1""u""'
7 Notary (Seatr gy*"'
//)M7/87
[
NOTARY
}
My commission expires:
=
it rusuc /cf!
ud,
.