ML20069E438

Technical Evaluation Rept on Monitoring of Electric Power to Reactor Protection Sys for Brunswick Steam Electric Plant,Units 1 & 2

ML20069E438
Person / Time
Site:	Brunswick
Issue date:	04/26/1982
From:	Selan J LAWRENCE LIVERMORE NATIONAL LABORATORY
To:	Office of Nuclear Reactor Regulation
Shared Package
ML20069E432	List: ML20069E438
References
CON-FIN-A-0250, CON-FIN-A-250 UCID-19135, NUDOCS 8209230619
Download: ML20069E438 (8)

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"lCCllNICAL EVALUATIO!; REPORT ON Tile !!0NITORING OF ELECTRIC POWER TO Tile p ,

REACTOR PROTECTION SYSTE!! FOR Tile

,{f BitUNSUICK STEN! ELECTRIC PLANT, UNITS 1 AND 2 Janes C. Selan

,ts (Docket Hos.50-325, 50-324) i April 26, 1902 0

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This is an informal report intended primarily for internal or limited external distribution. $g72

• - ^ M x The opinions and conclusions stated are those of the author and may or may not be those ^

1 of the Laboratory.

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This work was supported by the United States Nuclear Regulatory Commission under 1.

a Memorandum of Understanding with the United States Department of Energy.

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ABSTRACT lu

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This report documents the technical evaluation of the monitoring of electric power to the reactor protection system (RPS) at the Brunswick Steam Electric Plant, Units 1 and 2. The evaluation is to determine if the proposed design modification will protect the RPS from abnormal voltage and frequency conditions which could be supplied f rom the power supplies and will meet certain requirements set forth by i the Nuclear Regulatory Commission.

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The proposed design modifications with time delays verified by GE, will protect the RPS f rom sustained abnormal voltage and f requency conditions from the supplying sources.

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i FOREWORD d

t This report is supplied as part of the Selected Electrical, l

Instrumentation, and Control Systems Issues Program being conducted for the U. S. Nuclear Regulatory Commission, Of fice of Nuclear Reactor Regulation, Division of Licensing, by Lawrence Livermore National La bo rato ry.

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The U. S. Nuclear Regulatory Commission funded the work under ,

the authorization entitled " Electrical, Instrumentation and Control i System Support," B&R 20 19 04 031, FIN-A0250.

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TABLE OF CONTENTS Page

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1. INTRODUCTION . . . . . . . . . . . . . .

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2. DESIGN DESCRIPTION . . . . . . . . . . . . .

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3. EVALilATION . . . . . . . . . . . . . .

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4. CONCl.llSION . . . . . . . . . . . . . . .

. . . . . . . 5 REFERENCES . . . . . . . . .

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1 TECHNICAL EVALUATION OF THE MONITORING OF ELECTRIC POWEK

- TO THE REACTOR PROTECTION SYSTEM AT THE BRUNSWICK STEAM ELECTRIC PLANT UNITS 1 AND 2 (Docket Nos. 50-325, 50-324)

James C. Selan Lawrence Livernore National Laboratory, Nevada

1. INTRODUCTION J

Du'ing the operating license review for Hatch 2, the Nuclear i Regulatory Commission (NRC) staf f raised a concern about the capability t of the Class IE reactor protection system (RPS) to operate after suffering sustained, abnormal voltage or frequency conditions f rom a non-Class 1E power supply. Abnormal voltage or f requency conditions could be produced as a result of one of the following causes: combinationa of undetected, random single failures of the power supply components, or multiple f ailures

[ of the power supply components caused by external phenomena such as a seismic event.

The concern for the RPS power supply integrity is generic to all General Electric (GE) boiling water reactors (BWR) MARK 3's, MARK 4's, and

!! ARK 5's and all BUR t1 ARK 6's that have not elected to use the solid state RPS design. The staff therefore pursued a generic resolution. Accordingly, GE proposed a revised design, in conceptual form, for rasolution of this concern [Ref. 1]. The proposed. modification consists of the addition of two Class 1E " protective packages" in series between each RPS motor generator

(!!-C) set and it's respective RPS bus, and the addition of two similar ,

packages in series in the alternate power source circuit to the RPS buses.

Each protective package would include a breaker and associated overvoltage, undervoltage and underfrequency relaying. Each protective package would meet the testability requirements for Class IE equipment.

i With the protective packages installed, any abnormal output type' failure (undetectable random or seismically caused) in either of the two RPS M-G sets (or the alternate supply) would result in a trip of either one or

( both of the two Class IE protective packages. This tripping would interrupt l the power to the effected RPS channel, thus producing a scram signal on that I channel, while retaining full scram capability by means of the other channel.

Thus, fully redundant Class IE protection is provided, bringing the overall l

RPS design into f ull confornance with General Design Criteria (CDC)-2

[Ref. 2], and GDC-21 [Ref. 3] (including IEEE-279 [Ref. 4] and the standard review plan [Ref. 5]). The NRC staff reviewed the proposed CE design and concluded that the modification was acceptable [Ref. 6],

and should be implemented in conformance with the applicable criteria for Class IE systems.

The NRC requires that the components of the RPS not be exposed to unacceptable electric power of any sustained abnormal quality that could damage the RPS. This involves providing means to detect any overvoltage, undervoltage, or underfrequency condition that is outside the design limits of the RPS equipment and to disconnect the RPS from such abnormal electric power before damage to the RPS can occur. The equipment which performs these functions must satisfy the single failure criterion and be seismically qualified. The NRC issued a generic letter [Ref. 7] to all operating BWR's requesting the Itcensees to submit design modification details and Technical Gpecifications for post implementation review.

By letters dated December 11' 0 ,1980 [Ref. 8], and January 29, 1982

[Ref. 9], Carolina Power and Light Company (CP&L), the licensee, submitted design modification details regarding the monitoring of electrical power to the RPS at the Brunswick Steam Electric Plant, Units 1 and 2.

The purpose of this report is to evaluate the licensee's submittal with respect to the NRC criteria and present the reviewer's conclusion on the adequacy of the design modifications to protect the RPS f rom abnormal voltage and frequency conditions.

2. DESIGN DESCRIPTION The licensee has proposed to install the CE designed " electrical protection assembly" (GE No. 914E175) to monitor the electric power in each of the sources of power (two M-G sets and an alternate source per each unit) to the RPS. Each assembly consists of two identical and redundant packages.

Each package includes a circuit breaker and a monitoring module. When abnormal electric power is detected by either module, th'e respective l circuit breaker will trip and disconnect the RPS from the abnormal power source.

The monitoring module detects overvoltage, undervoltage, and underfrequency conditions and provide; a time-delayed trip when a setpoint is exceeded.

3. EVALUATION The NRC stated several requirements that the licensee must meet in their design modification to monitor the power to the RPS. A statement of these requirements followed by an evaluation of the licensee's submittals is as follows:

(1) "The components of the RPS shall not be exposed to unacceptable electric power of any sustained abnormal quality that could damage the RPS."

The monitoring module will detect overvoltage, undervoltage, and underfrequency conditions with the following setpoints. The chosen setpoints are within the ratings of the RPS components and thus ensure their protection from sustained abnormal power:

Nominal voltage 120 volts, 60 Hz nominal Condition Setpoint Time Delay overvoltage < 132 Volts Undervoltage 2;108 Volts Underfrequency 2; 57 Hz

• The licensee states that the actual time delays to be selected (with respect to their voltage and frequency setpoints) will be in the range of 1.0 second or less.

Upon installation and testing, the final time delays selected will be verified by CE to ensure that the RPS components will be protected with the chosen setpoints from sustained abnormal power [Ref. 10].

(2) " Disconnecting the RPS from the abnormal power source shalI be automatic."

The monitoring module will automatically disconnect the RPS buses from the abnormal power supply after the set tine delay should the parameters setpoints be exceeded.

(3) "The power nonitoring system shall meet the requirements of IEEE 279-1971, CDC-2 and CDC-21."

The monitoring packages meet the Class IE requirements of IEEE 279, the single failure criteria of GDC-21, and the seismic qualifications of GDC-2.

l (4) " Technical Specifications shall include limiting conditions of operation, surveillance requirements, and trip setpoints."

Formal Technical Specifications will be submitted upon installation and final testing [Ref. 10]. The protective packages are currently planned for installation during the 1982 refueling cycle (late Spring for Unit 2 and Fall for Unit 1).

4. CONCLUSION 1

i Based on the information submitted by Carolina Power and Light Company for the Brunswick Steam Electric Plant, Units 1 and 2, it is concluded that:

(1) The proposed setpoints of the relays in the two protective packages to be installed in series, in each of the power sources to the RPS buses, will automatically protect the RPS components f rom sustained abnormal overvoltage, under-

itiltage, and underf requency conditions outside the design limits of the RPS components.

(2) The protective packages meet the requirements of Class lE equipment (IEEE 279), single failure criteria (GDC-21), and seismic qualification (CDC-2).

(3) The final time delays selected will be verified by CE to ensure that the RPS components will not be damaged or 1 prevent the RPS from performing its safety functions before circuit breaker tripping occurs.

(4) The Technical Specifications, when submitted, will be judged acceptable provided they contain:

(a) The setpoints and time delays verified by GE as stated 4

in Section 3.0, Item 1.

(b) Address limiting conditions of operation for an inoperable power monitoring system to be restored in 30 minutes or remove the source associated with the inoperable power monitoring system. One package may be inoperable, as necessary for testing and maintenance, not to exceed 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> per month.

(c) Surveillance requirements for determining the operability of the RPS power monitoring system instrumentation to include a functional test at least <>.ce per 6 months and a channel calibration once per operating cycle of the protective instrumentation including simulated automatic actuation, tripping logic, output circuit breaker tripping, and verification of the setpoints.

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. 1 REFERENCES  ;

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1. Cencral Electric Company letter, MFN 408-78 (C. C. Sherwood) to NRC (R. S. Boyd), dated October 31, 1978.

2. Cencral Design Criteria-2 (CDC-2), " Design Bases for Protection Against Natural Phenomena," of Appendix A, " General Design Criteria for Nuclear Power Plants," in the Code of Federal Regulations, Title 10, Pa rt 50 (10 CFR 50).

3. General Design Criteria-21 (GDC-21), " Protection System Reliability and Testability," of Appendix A, " General Design Criteria for Nuclear Power Plants," in the Code of Federal Regulations, Title 10, Part 50 (10 CFR 50).

4. IEEE Std. 279-1971, " Criteria for Protection Systems for Nuclear Power Generating Stations."

5. NUREG-75/087, " Standard Review Plan for the Review of Safety Analysis Reports for Nuclear Power Plants."

6. NRC memorandum from Faust Rosa to J. Stolz, T. Ippolito, and G. Lainas, dated February 19, 1979.

7. NRC letter to Operating BWR's, dated September 24, 1980.

8. CP&L Ictter (E. E. Utley) to NRC (Thomas A. Ippolito), dated December 10, 1980.

9. CP&L Ictter (P. W. Ilowe) to NRC (D. B. Vassallo), dated January 29, 1982.

10. Telecon, C. Schuker (CP&L), B. Poulk (CP&L), J. VanVliet (NRC), and J. Selan (LLNL), February 25, 1982.

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