ML13317B131
| ML13317B131 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 04/30/1982 |
| From: | Krieger R Southern California Edison Co |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML13310A244 | List: |
| References | |
| RTR-NUREG-737, TASK-04-02, TASK-15-08, TASK-15-10, TASK-15-8, TASK-4-2, TASK-RR NUDOCS 8205040366 | |
| Download: ML13317B131 (3) | |
Text
Southern California Edison Company P.O BOX 800 2244 WALNUT GROVE AVENUE ROSEMEAD, CALIFORNIA 91770 April 30, 198 Director, Office of Nuclear Reactor Regulation Attention:
D. M. Crutchfield, Chief Operating Reactors Branch No. 5 8
M1IY S19822~ 2 Division of Licensing DOUETYMAN 1SS1E N
U. S. Nuclear Regulatory Commission NIO a Washington, D.C.
20555 Gentlemen:
Subject:
Docket No. 50-206 SEP Topic IV-2 Reactivity Control Systems San Onofre Nuclear Generating Station Unit 1 In accordance with the redirection of the Systematic Evaluation Program, enclosed is the draft assessment for SEP Topic IV-2, Reactivity Control Systems. If you have any questions on this assessment or require additional information, please let us know.
Sincerely, R. W. Krieger Supervising Engineer San Onofre Unit 1 Licensing Enclosure 920504,0366 820430 PDR ADOCK 05000206 PDR
0 9
SAFETY EVALUATION REPORT SEP TOPIC IV-2, REACTIVITY CONTROL SYSTEMS INCLUDING FUNCTIONAL DESIGN AND PROTECTION AGAINST SINGLE FAILURES SAN ON0FRE NUCLEARGENERANTG STATIONI UNIT 1 DOCKET NO. 50-206 I. INTRODUCTION The purpose of this evaluation is to insure that the design basis for the San Onofre Unit 1 reactivity control systems is consistent with analyses performed to verify that the protection system meets General Design Criterion 25.
General Design Criterion 25 requires that the reactor protection system be designed to assure that specified acceptable fuel desi.gn limits are not exceeded for any single malfunction of the reactivity control systems, such as accidental withdrawal of control rods. Reactivity control systems need not be single failure proof.
However, the protection system must be capable of assuring that acceptable fuel design limits are not exceeded in the event of a single failure in the reactivity control systems.
The review criterion, covered in this evaluation, is addressed Section II. Review areas that are not covered, but are related and essential to the completion of this topic, are covered by SEP topics addressed in Section III.
The scope of the SEP topics is defined in the "Report on the Systematic Evaluation of Operating Facilities" dated November 25, 1977.
This report is limited to the identification and evaluation of inadvertent control rod withdrawals and malpositioning of control rods which may occur as a result of single failures in the electrical circuits of the reactivity control systems.
II. REVIEW CRITERION The review criterion for this topic is based upon Section 7.7, Part II of the NRC Standard Review Plan. In the specific case of the reactivity control systems a single failure shall not cause plant conditions more severe than those for which the reactor protection system is designed.
III. RELATED SAFETY TOPICS The following listed review areas are not covered in this report, but are related and essential to the completion of this topic. These review areas are covered by other SEP topics as indicated below.
- 1. Analyses of the consequences of control rod withdrawals and the malpositioning of control rods which may occur as a result of single failures in the electrical circuits of the reactivity control systems are covered by SEP Topic XV-8, "Control Rod Misoperation (System Malfunction or Operator Error)."
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- 2. Analyses of reactivity insertions occurring as a result of inadvertent boron dilutions are covered in SEP Topic XV-10, "Chemical and Volume Control System Malfunction that Results in a Decrease in Boron Concentration in the Reactor Coolant."
IV.
REVIEW GUIDELINES The purpose of this evaluation is to identify inadvertent control rod withdrawals and malpositioning of control rods which may occur as a result of single failures in the electrical circuits of the reactivity control systems for San Onofre Unit 1.
V. EVALUATION Appendix A provides a description of the rod control system, a failure modes and effects analysis of the system, and a description of design features which limit control rod withdrawals and malpositioning of control rods caused by failures within the reactivity control systems at San Onofre Unit 1. Based upon this information it is concluded that the following may occur as a result of single failures:
- 1. Control rod or rod group drop.
- 2. Blocking of rod movement which results in control rod or rod group misalignment.
- 3. Erroneous rod insertion or withdrawal.
In summary, the FMEA shows that most single failures are in the safe direction (i.e., rod movement is blocked or rods are dropped into the reactor) and that either an alarm is actuated to detect failures or the reactor is tripped to insure that the reactor core is maintained within safe design limits.
VI.
CONCLUSION The review of SEP Topic XV-8, should include consideration of the items listed above.
VII. REFERENCES
- 1. San Onofre Unit 1 Final Safety Analysis, Section 5.3.
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