ML20010E121
| ML20010E121 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 08/28/1981 |
| From: | Crutchfield D Office of Nuclear Reactor Regulation |
| To: | Counsil W NORTHEAST NUCLEAR ENERGY CO. |
| References | |
| TASK-07-03, TASK-7-3, TASK-RR LSO5-81-08-069, LSO5-81-8-69, NUDOCS 8109030118 | |
| Download: ML20010E121 (5) | |
Text
A August 28, 1981 Docket No. 50-245 LS05-81 08-069 g
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Mr. W. G. Counsil Vice President J
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Dear Pr. Counsil:
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SUBJECT:
Si.P TOPIC VII-2. E"GINEERED SAFETY FEATURES (ESF) SYSTEM C0ilTROL LOGIC AND DESIGN, SAFETY EVALUATION FOR MILLSTONE 1 The enclosed staff safety evaluation is based on a contractor document that has been made available to you previously. This evaluation suoports the findings of the staff safety evaluation of Topic VII-2 and proposes nodifications to some equipnent to improve electrical isolation.
The need to actually inplement these changes will be deternined during the integrated safety assessment. This topic assessment may be revised in the future if your facility design is changed or if NRC criteria relating to this topic are nodified before the integrated assessment is consleted.
Sincerely, Dennis it. Crutchfield, Chief l
Onorating Reactors Branch No. 5 Division of Licensing
Enclosure:
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MILLSTONE 1 Docket No. 50-245 Mr. W. G. Counsil CC William H. Cuddy, Esquire Connecticut Energy Agency Day, Berry & Howard ATIN: Assistant Director Counselors at Law Research and Policy One Constitution Plaza Development Hartford, Connecticut 06103 Department of Planning and Energy Policy Natural Resources Defense Council 20 Grand Street 91715th Street, N. W.
Hartford, Connecticut 06106 Washington, D. C.
20005 Northeast Nuclear Energy Company ATTN: Superintendent Millstone Plant P. O. Box 128 Waterford, Connecticut 06385 Mr. Richard T. Laudenat 5
Manager, Generation Facilities Licensing Northeast Utilities Service Company P. O. Box 270 Hartford, Connecticut 06101 Resident Inspector c/o U. S. NRC P. O. Box Drawer KK i
Niantic, Connecticut 06357 Waterford Public Library 2
Rope Ferry Road, Route 156 Waterford, Connecticut 06385 First Selectman of the Town of Waterford i
Hall of Records 200 Boston Post Road l
Waterford, Connecticut 06385 l
John F. Opeka Systems Superintendent Northeast Utilities Service Company P. O. Box 270 l
Hartford, Connecticut 06101 U. S. Environmental Protection Agency Region 1 Office ATTN: EIS C0ORDINATOR JFK Federal Building Boston, Massachusetts 02203
SYSTEMATIC EVALUATION PROGRAM TOPIC Vll-2 MILLSTONE 1 i
TOPIC:
Vll-2 I.NGINEEREDSAFETYFEATURES_(ESF)_SYSTEMCONTROL1.0GIC I
AFD DLSIGN l
I.
INTRODUCTION DuringthestaffreviewoftheSafetyinjectionSystem(SIS) reset (issue i
f4 in NUREG-0138) the staff determined that the Engineered Safety features Actuation Systems (ESTAS) at both N Rs and BURS may have design features that raise questions about the independence of redundant channels, the interaction of reset features and individual equi; ment controls, and the interaction of the ESFAS logic that controls transfers between on-site l
and off-site power sources.
Review of the as-built logic diagrams and schematics, operator action required to supplement the ESTAS automatic actions, the startup and surveillance testing procedures for demonstrating ESFAS performance appeared to be required.
Several specific concerns exist with regard to the manual SIS reset feat-ure following a LOCA.
They are:
(1) If a loss of offsite power occurs after reset, operator action would be required to remove normal shutdown cooling loads from the emergency bus and re-establish emergency cooling loads.
Time would be critical if the loss of offsite power occurred within a few minutes following a LOCA.
(2) If loss of offsite power oc-t i
curs af ter reset, some plants may not restart some essential loads such as diesel cooling water.
(3) The plant may suffer a loss of ECCS delivery for some time period before emergency power picks up the ECCS system.
It was also decided to review the ESF system control logic and design, in-cluding bypasses, reset features and interactions with transfers between onsite and offsite power sources.
Since these decisions were made in early 1977, the staff's plans for re-solving these issues have changed.
Two generic reviews of the diesel generator problems have been conducted by Inspection and Enforcement.
The second review includes consideration of bypasses and resets.
In ad-dition, Task Action Plan Generic Task B-24 is involved with reset and by-pass concerns.
Accordingly, this SEP Topic has been modified to reduce duplication of effort.
As a result of the staff's review of the scope of the several related
.generi,c efforts and the other SEP Topics, it was decided that the only area that had not been covered was the independence of redundant logic trains.
Independence might be compromised by sharing input signals and the use of common controls such as mode switches, reset switches, and logic test facilities.
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l II.
REVIEW CRI_T_ERIA i
The current licensing criteria are presented in Section 2 of EG&G Report 0419J, " Engineered Safety Features (ESF) System Control Logic and Design."
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I III. RELATED SAFETY T_0 PICS AND INTERFACES 4
l The scope of review for this topic was limited to avoid duplication of effort s'ince some aspects of the review were performed under related l
topics.
The related topict and the subject matter are identified below, i
Each of the related topic reports contain the acceptance criteria and review guidance for its subject matter.
III-6 Seismic Qualification III-11 Seismic Qualification III-12 Environmental Qualification I
IV-1.A Operation with less than All Loops in Operation VI-4 Bypass and Reset of Engineered Safety Features (B-24)
VI-7.A.3 ECCS Actuation System VI-7.B ESF Switchover from Injection to Recirculation j
VI-7.C.1 Independence of Onsite Power VI-7.C.2 Failure l' ode Analysis-ECCS V.1-7.C.3 The effect of loop isolation valve closure on ECCS performance j
YI-7.D Long Term Cooling Passive failures (e.g. flooding)
VI-7.F Accumulator Isolation Valves VI-10.A Testing of Reactor Protection Systems i
VI-10.B Shared Systems VII-1.A Reactor Trip System Isolation VII-3 Systems Required for Safe Shutdown l
VIII-2 Onsite Emergency Power Systems VIII-3 Emergency de Power Systems VIII-4 Electrical Penetrations IX-3 Ventilation IX-6 Fire Protection The conclusion that suitable isolation devices are provided is a basic assumption for Topics VI-7.C.? and VII-3.
IV.
REVIEW GUIDELINES The review guidelines are presented in Section 3 of Report 0419J,
" Engineered Safety Features (ESF) System Control Logic and Design."
V.
EVALUATION i
A description of the isolation devices employed in Millstone 1 and a l
comparison with current design criteria are presented in Report 0419J,
" Engineered Safety Features (ESF) System Control Logic and Design."
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VI.
CONCLUSION As a result of our review of our contractor's work the staff concludes that Millstone 1 does not conform to current licensing criteria for electrical isolation of redundant safety features and the plant should be modified to satisfy IEEE Std. 279-1971 in this regard.
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