ML14138A079

Forwards Evaluation of SEP Topic IV-2, Reactivity Control Sys. Requests Response in 30 Days If Facility Differs from Licensing Basis Assumed in Assessment

ML14138A079
Person / Time
Site:	San Onofre
Issue date:	09/14/1982
From:	Paulson W Office of Nuclear Reactor Regulation
To:	Dietch R Southern California Edison Co
References
TASK-04-02, TASK-4-2, TASK-RR LSO5-82-09-042, LSO5-82-9-42, NUDOCS 8209220149
Download: ML14138A079 (6)

Text

September 14, 1982 Docket No. 50-206 LS05-82-09-042 Mr. R. Dietch, Vice Prdlident Nuclear Engineering and Operations Southern California Edison Company 2244 Walnut Grove Avenue Post Office Box 800 Rosemead, California 91770

SUBJECT:

SEP TOPIC IV-2, REACTIVITY CONTROL SYSTEMS SAN ONOFRE NUCLEAR GENERATING STATION, UNIT 1 Enclosed is a copy of our evaluation of SEP Topic IV-2, Reactivity Control Systems for San Onofre Unit 1. This assessment compares your facility, as described in Docket No. 50-206, with the criteria currently used by the regulatory staff for licensing new facilities. Please inform us if your as-built facility differs from the licensfig basis assumed in our assess ment.

Your response within 30 days of the date you receive this letter is requested.

If no response is received within that time, we will assume that you have no comments or corrections. This evaluation will be a basic input toturt review of your evaluation of Topic XV-8and the Integrated Safety Assessment for your facility unless you identify changes needed to reflect the as-built conditions at your facility. This assessment may be revised in the future if your facility design is changed or if NRC criteria relating to this subject are modified before the Integrated Assessment iis completed.

Sincerely, prig;inal signed by:

Walter Paulson, Project Manager Operating Reactors Branch No. 5 bivision of Licensing

Enclosure:

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San Onofre Unit 1 rp M.r. R. Dietch Docket No.

50-206 Revised 3/30/82 cc Charles R. Kocher, Assistant General Counsel James Beoletto, Esquire Southern California Edison Company Post Office Box 800 Rosemead, California 91770 David.R. Pigott Orrick, Herrington & Sutcliffe 600 Montgomery Street San Francisco, California 94111 Harry B. Stoehr San Diego Gas & Electric Company P. 0. Box 1831 San Diego, California 92112 Resident Inspector/San Onofre NPS c/o U. S. NRC P. 0. Box 4329 San Clemente, California 92672 Mayor City of San Clemente San Clemente, California 92672 Chairman Board of Supervisors County of San Diego San Diego, California 92101 California Department of Health ATTN: Chief, Environmental Radiation Control Unit Radiological Health Section 714 P Street, Room 498 Sacramento, California 95814 U. S. Environmental Protection Agency Region IX Office ATTN:

Regional Radiation Representative 215 Freemont Street San Francisco, California 94111 Robert H. Engelken, Regional Administrator Nuclear Regulatory Commission, Region V 1450 Maria Lane Walnut Creek, California 94596

SAFETY EVALUATION REPORT SEP TOPIC IV-2, REACTIVITY CONTROL SYSTEMS INCLUDING FUNCTIONAL DESIGN AND PROTECTION AGAINST SINGLE FAILURES SAN ONOFRE 1 NUCLEAR GENERATING STATION DOCKET NO. 50-206 INTRODUCTION The purpose of this evaLuation is to insure that the design basis for the San Onofre 1 reactivity controL systems is consistent with analyses performed to verify that the pro tection 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 maL function of the reactivity controL systems, such as accidental withdrawaL of controL rods.

Reactivity control systems need not be single feiLure proof.

However, the protection system must be capable of assuring that accept able 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.

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 of inadvertent controL rod withdrawaLs and malpositioning of.control rods which may occur as a result of single failures in the control rod drive system.

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 re port, 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 cil cuits 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 cover ed in SEP Topic XV-10, "Chemical and Volump

Control System MaLfunction that Results in a De crease 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 faiLure in the con troL rod drive system for the San Onofre 1 Nuclear Power Plant.

V.

EVALUATION Information was provided in Southern CaLifornia Edison Company Letter dated April 30, 1982, describing single failures within the controL rod drive system which can cause controL rod withdrawaLs and maLpositioning of con trol rods at the San Onofre NucLear Generating Station, Unit 1. ALso incLuded was a.description of design features which Limit reactivity insertion rates and rod malpositionings resulting from single failures.

Based upon an audit review of the information provided by the Licensee we conclude that the foLLowing may occur as a re sutt of single failures:

1)

Two banks of controL rods may move simuLtaneousLy instead of one bank.

2)

Two groups of rods could move simultaneousLy instead of one group.

3)

A cLuster, group.

or bank of shutdown rods may not move when movement is commanded.

4)

A cLuster, cLusters, group.

bank, or banks of con trol rods may not move when movement is commanded.

5)

A group or bank of shutdown rods could move inadvertentLy.

6)

A group, bank or banks (in overLap region) of controL rods couLd move inadvertently.

7)

An individuaL shutdown rod or a cluster, group, or bank of shutdown rods could faLL into the core.

8)

An individual controL rod or cluster, clusters, group.

bank or banks of controL rods couLd faLL into the core.

9)

A cLuster of rods couLd move opposite to the commanded direction.

This concLusion is based upon the design of the controL rod drive system.

It shouLd be noted that the above items are more encompassing as to the grouping of rods affected by singte faiLures than those provided in the Licensee's Letter.

VI.

CONCLUSION The results of this topic will be used by the staff in our review of the licensee report on Topic XV-8.