ML17194A299
| ML17194A299 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 11/30/1981 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Delgeorge L COMMONWEALTH EDISON CO. |
| References | |
| TASK-08-04, TASK-8-4, TASK-RR LSO5-81-11-084, LSO5-81-11-84, NUDOCS 8112040501 | |
| Download: ML17194A299 (4) | |
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_1-November 30, 1981 Docket No. 50-237 LSOS11-084 '
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/Mr;~ "L *'Qe\\ Geqr~e...
Director of Nucle*ar Licensing Commonwealth Edison Company Post Office Box 767 Chicago, Illinois 60690
/jk:-r* Mr... :*bel §~6r:g~--: *~_j
SUBJECT:
SEP TOPIC VIII-4, ELECTRICAL PENETRATIONS OF.REACTOR CONTAINMENT - SAFETY EVALUATION REPORT (DRESDEN UNIT
- 2) is the staff's safety evaluation report for SEP Topic VIII-4.
The basis for Enclosure 1 is given in Enclosure 2.
" is our contractor's technical evaluation that has been revised by the additional infonnation and comments provided in your letter of June"25, 1981.
- is the staff's position with regard to the acceptabi11Jcy of the electrical.penetrations for your facility.
The staff has concluded that your commitments to assure that your facil.ity meets current 1 icensing criteria is an acceptable basis for considering this topic eomplete.
Enclosure:
As stated Sincerely, Dennis M. Crutchfield, Chief Operating Reactors Branch No. 5 Division of Licensing Ai>t>'*.
(::). c~"'/;"°"
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- cc w/enelosure:
See hext page NRC FORM 318 (10-80) NRCM 0240 OFFICIAL RECORD COPY USGPO: 1981-3JS-960
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Mr. L. DelGeorge cc Isham, Lincoln & Beale Counselor~ at Law One First National Plaza, 42nd Floor Chicago, Illinois 60603 Mr. D-Oug Scott.
Plant Superintendent
- . Rural Route #1 Morris, Illinois 60450 U. S. Nu cl ear Regulatory Comnii ssion Resident I nspector,s Office Dresden Station
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RR #1 1/.
M6rris, Illihois 160450 Mary Jo Murray
- Assistant Attorney General Environmental Control Division 188 W. Randolph Street Suite 2315 Chicago, Illinois 60601 Morris Public Library 604. Liberty Street
~orris, Illinois 60451 Chairman Board of Supervisors of Grundy County
- Grundy Co~nt.)'- Courthouse i-':-orris, Illinois 60450 Illinois Department of Nuclear Safety 1035 Outer Park Drive, 5th Floor.
Springfield, Illinois 62704 U. s. Environmental Protection Age*ncy F~deral Activities Branch Region V Office.
ATTN:
Regional Radiation Representative*
230 South Dearborn Street Chica9o, Illinois* 60604 The Honorable Tom Corcoran United States House of Representatives
- Washington, D. C_.
20515 John H. Frye, III, Chairman Atomic Safety and Licensing Board
- u. S.. Nuclear Regulatory Commission Washington, D. C.
20555
.e Daniel Mintz Counsel for Petitioners
. (Citizens for a Better Environment)
Suite 1600, ~9 E. Van Buren Str~et Chicago, Illinois 60605
ENCLOSURE l SYSTEMATIC EVALUATION PROGRAM.
TOPIC VIII-4 DRESDEN UNIT 2.
TOP IC VI I.I-4, ELECTRICAL PENETRATIONS. OF REACTOR CONTAINMENT I.*'-
INTRODUCTION The safety objective of Topic VIII-4, 'Electrical Penetrations of Reactor Coniainment, 11 is to assure that all.electrical penetrations in the contain-ment structure,are designed not to f~il from electrical faults during a high energy line break.
As part of the.Systematic Evaluation Program (SEP) the NRC staff performed an audit, comparing sample containment electrical penetrations in SEP facilities with current licensing criteria for protection against fault and overload* currents following a postulated accident.
II.
REVIEW CRITERIA The review criteria are presented in Section 2.0 of EG&& Report EGG-EA-*
5627, "Electrical Penetrations of the Reactor Containment."
In addition, in licensing new plants, the staff requires compliance with the recorrnnenda-
. tions of Regulatory Guide 1.63 or an* acceptable alternative method.
For each* containment eJectrical penetration, the protective systems should provide primary and backup circuit protection devices to prevent a single failure in conjunction with a circuit overload from impairing containment*
integrity.
The primary and backup protection devices must have trip time vs. current response characteristics which assure protection *against penetration failure.
The protection devices are to be periodically tested to verify trip setpoints and adequacy of response.
No single failure should allow excessive currents in the penetration conductors that will degrade the penetration seals.
Where external control power is used for actuating the protection systems the power for primary and backup breakers should be derived from *separate sources.
_Dvercurrent signals for tripping primary and backup system devices should be electrically independent anQ physically separated.
III.
RELATED SAFETY TOPICS AND INTERFACES
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The scope of review for this topic was limited to avoid duplication of effort since some aspects of the review were p~rformed under the related Topic III-12. "Environmental Qualification.". The related topic report contains the acceptance criteria and review guidance for its.subject matter.
_f, Theoretically, there are no safety topics that are dependent on the present topic information for their completion, however, the results of the present topic have a definite impact upon the capability of equip~
ment* inside of containrrent to function after a high energy line break.
IV.
REVIEW GUIDELINES v~
Tlie review guidelines are presented in Secti_on 3. 0 of EG&G Report EGG-EA-5627, "Electrical Penetrations of the Reactor Containment."
EVALUATION As noted in the EG&G Report on this topic with a LOCA environment inside containment, th¢. protection for sorre low voltage penetrations do not confonn
. to the current nicensing criteria, but the medium voltage penetrations are
- . adequately protected.
However, the 1 icensee has implemented a corrective*
program which is described in their June 25, 1981 submittal.
Their program includes qualifying sorre low voltage circuits inside of containment and demonstrating the ~dequacy of the low voltage primary protection devices over the range df 200 to 600 amperes... Where Class 1£ circuits are not provided, the litensee will provide suitable backup pro-tection or, will assure that the circuit is either de-energized during operation or, is.de-energized by an accident signal.
Furthermore, the staff notes that lhe low voltage* penetration type (NS04) was approved previously for Millstone Unit 1.
In our review of Millstone Unit 1, the staff used a lower qualification temperature of 325°F (177°C) and an initial temperature of 90°C for the outer seal with a higher *{1600 ampere) fault current.
VI.
CONCLUSIONS
- As a result of our review*we have concluded that a suitable program is in* pl ace to.assure that the low voltage penetrations conform to the current licensing criteria.
We also have concluded that the present design of the medium voltage penetrations is ac~eptable.
- The results of previti~s reviews using higher currents and lower qualifica-
- tjon 1 imits indicate that there is no significant risk in the.continued operation of Dresden 2 during the time required to complete the present.
breaker testing program because of the.margins_t'hat appear to be available between outer seal damage and the breaker trip l;imits.
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