ML17258A908
| ML17258A908 | |
| Person / Time | |
|---|---|
| Site: | Ginna  |
| Issue date: | 03/24/1981 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML17258A909 | List: |
| References | |
| TASK-04-02, TASK-15-08, TASK-15-10, TASK-4-2, TASK-RR NUDOCS 8103260621 | |
| Download: ML17258A908 (4) | |
Text
SAFETY EVALUATION REPORT SEP TOPIC IV-~2 REACTIVITY CONTROL SYSTEMS INCLUDING FUNCTIONAL DESIGN AND PROTECTION AGAINST SINGLE FAILURES R.E.
GINNA NUCLEAR POWER PLANT DOCKET NO. 50-244 I.
INTRODUCTION The purpose of this evaluation is to insure that the design basis for the Ginna 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 design 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 re-view criterion, covered in this evaluation, is addressed in Section II.
Review areas that are not covered, but are related and essential to the completion of this topic, are covered by other 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 mal positioning of control rods which may occur
'I as a result of single failures in the electrical circuits of the reactivity control systems.
II. REVIBI 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 con-
trol 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.
l.
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)"
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 the R.E. Ginna Nuclear Power Plant.
V.
EVALUATION Information was provided in Rochester Gas and Electric Corporation letter dated January 19, 1981, describing design features which limit control rod withdrawals and malpositioning of control rods caused by failures within the reactivity control systems at the R.E. Ginna Nuclear
Power Plant.
Based upon the information provided by the licensee we conclude that the following may occur as a result of single failures:
1)
Two control rod banks may be simultaneously withdrawn.
2)
Two banks may overlap at other than the design value.
This conclusion is based upon the availability of alarm and interlock circuits associated with the rod control system such that certain consequential effects of single failures within the rod control system are precluded by the operability of these interlocks and alarms.
The basis for the assumption that these alarms and interlocks will be opera-ble is that a failure in the alarm and interlock circuits will be identified and corrected during routine maintenance or as a result of system fault investigation.
The effects of single failures occurring after an undetected failure has occurred in the alarm and interlock system are not included in the evaluation.
This is consistent with the basis used for plants currently under operating license review.
VI.
CONCLUSION Each of the following two reactivity control system malfunctions have been addressed as part of SEP Topic XV-8 to verify that specified acceptable fuel design limits are not exceeded:
1)
Simultaneous withdrawal of two control rod banks.
2)
Overlap of two banks at other than the design value.
Fuel design limits are not exceeded for either of the above two mal-functions and thus, General Design Criterion 25 is met insofar as electrical failures within reactivity control systems are concerned.
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