ML20247G531
| ML20247G531 | |
| Person / Time | |
|---|---|
| Site: | Dresden, Byron, Braidwood, Quad Cities, Zion, LaSalle, 05000000 |
| Issue date: | 03/20/1989 |
| From: | Smith N COMMONWEALTH EDISON CO. |
| To: | Davis A NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| Shared Package | |
| ML20247G530 | List: |
| References | |
| 0056T, 56T, NUDOCS 8905310003 | |
| Download: ML20247G531 (16) | |
Text
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D' - Commonwealth Edison -
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) 'One First National Plaza, Chicago, Ilhnois j
, ( O ". Address Reply to: Post Office Box 767
'PhlbRITVRg}q Chicago, Illinois 60690 tc p.ar 5
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. March 20, 1989
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Mr.-A.'Bert Davis L
' Regional' Administrator:
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U.S..Nuclest Regulatory Commission Region III
,799. Roosevelt Road Glen Ellyn, IL 60137 a
Subject Meeting Notes Regarding Commonwealth Edison D.C. Ground Policyj j
'j NRC Dpckey Nos. Sp-23,7/249; 50-254/265;L 50-373/374;150-295/364; 50-4'54/455; and l~
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50-456/457 Dear Mr. Davis On March 1, 1989 Commonwealth Edison met with Region III personnel in a working group level technical meeting to discuss the Edison's Corporate D.C.
Grounds Policy and.how it applies to the Edison Nuclear Stations. The overheads used at that meeting are Attachment I to this letter. The meeting provided for a good interchange of ideas and Edison believes resulted in the-Staff understanding Edison's interim and final D.C. Ground Policy. At the closure of the meeting the staff agreed that the Edison policies appeared appropriate and that Edison should continue with its implementation of the final policy and not wait for a formal NRC response.
~
L_Ca GLQM;Ld_P.Dlicy The D.C. Ground policy and considerations presented in Attachment I consists of the following main points:
a.
Two grounds of a significant magnitude are required to cause an event.
b.
The alarm point is at 125,000 ohms at the first ground.
c.
When an alarm occurs action is taken to find and ellminat.e the ground.
If the first ground is above 20,000 ohms the work is started within the next normal working shift (D1 priority).
If the first ground is less than 20,000 ohms the work is started immediately (Al priority). Work is continued until the ground is found.
8905310003 890518 PDR ADOCK 05000254 P
PDC HAR 31 M.
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l A.B. Davis March 20, 1989 d.
-If a ground cannot be located'or removed it may remain on the system for many months. This action.is justified because one i
ground does not render a_ system inoperable. No Technical Specifications Limitations are violat ed or exceeded.
If a second ground on the opposite polarity occurs causing a l
Technical Specification Limitation to be exceeded, (e.g.,
causes equipment failure) then the appropriate Technical Specification Limitation'will be observed.
If multiple
(
grounds occur and no limitation is exceeded than no Technical Specification requirements will be observed. The FSARs for CECO's BWR nuclear plants states the de system " operates ungrounded". CECO's interpretation of this statement is that a desig Lienture of the de system is it operates ungrounded.
The Ac11ggthsjils is that the system is operational until multiple grounds occur on each polarity of a magnitude to cause a Technical Limitation to be exceeded, f.
'The parameter monitored on the ground detector is ohms, but the actual meter indication is volts. The value of voltage is depender* on the ground detection circuitry (presentation slides 3 and 4 show the applicable relationship for CECO's equipment).
g.
ALsurvey was made of various utilities relative to their ground action response policies. CECO concluded they have a stringent policy. None of the other utilities surveyed are as conservative.
It was noted that item "a" through "d";above were features of the interim D.C. ground policy, presented on June 24, 1988 and included in the I.M. Johnson letter of July 19, 1988 to A.B. Davis.
NRC_CommenLn The NRC staff comments relative to Edison's D.C. Ground Policy weret a.
Some grounds can exist on an operating de ungrounded system, b.
A Draft Generic NRC letter for Justification for Continued Operation (JCO) will be issued shortly.
It states various time period for repairing equipment, 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />, 3 days, 7 days, 30 days etc.
The NRC Juggested Edison consider these time porlods when making their final policy.
Edison will review its' bases for choosing 14 days vs. son.a other time period.
4
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$.B. Davis 3-March 20, 1989 c.
NRC wanted to know if a' work' request with a B1 priority had to be completed within five working days.
B-1 work requests are considered urgent and must be scheduled within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. However, no specific completion time has been specified.
d.
When grounds cause an event in an "unmonitored". circuit,;how will the' operator know the' event occurred?
Edison considers unmonitored' circuits another topic and mostly unrelated to grounds.
In addition, all circuit failures are not due to grounds (e.g., a relay could fall by open circuiting).
Edison is currently reviewing what actions, if any, should undertake in this area. The Staff concurred with this position, e.
The NRC indicated they understood how the alarm set points were chosen and believed they are adequate.
l f.
The NRC understood Edison's position that the generic evaluation for the final ground was adequate and not in the form of a Safety Evaluation. The Staff concurred that when multiple grounds exist the Technical Specification Limits provide the necessary LCO's.
l l
g.
In response to an Edison statement that grounds are generally eliminated in one day, the NRC requested information on a Dresden Work Request that took 16 days to close in apparent l
contradiction to Edison's 14 day policy to eliminate or l-evaluate D.C. Grounds.
l l
In follow-up phone conversations Edison informed the Staff that the grour.d was on a non-tech spec piece of equipment.
As a result, the equipment was removed itom service thus eliminating the ground from the system immediately. The equipment was returned to service 16 days later without the ground.
Since the ground was removed from the D.C. system this is not considered a contradiction with the exieting policy, h.
The NRC' staff asked questions concerning the required management overview of technical evaluations of operating with grounds.
This item will be assigned to the D.C. Task force for developing a specific position.
L___.____-_-___-_-________.
i P
i.B. Davis March 20, 1989 1.
In response to specific questions being raised, the following items will be reviewed by the b Grounds Task force for possible inclusion in the D.C. Grounds Policy.
When a ground alarm exists, an operator should check via the local pushbutton mode for offsetting grounds at each shift.
Define the method of documentation for ground alarms including action taken and time the ground was cleared.
When a significant ground exists, testing of modified circuits may be prevented.
Recommend the management approval level that is required for ground evaluations performed on a grounds left on the system.
Provide the proper precautions for modification testing during the presence of significant grounds Very truly yours, N.P. Smith Nuclear Licensing Supervisor
/sc1 Attachment cc:
D.R. Muller - NRR T.M. Ross - Proje'ct Manager, NRR Senior Resident Inspectors (All Stations) 0056T 1-4
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IECHNICAL MEETING WITH RIII AND NRR ON l
CECO BATTERY GROUNDING POLICY s
MARCH 1, 19_8.1 12: 00 P.M.
I.-
INTRODUCTION p
II.
GROUND. DETECTION POLICY
- POLICY FEATURES
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- BASES FOR: POLICY.
III.
SURVEY OF OTHER UTILITIES IV.
FINAL GROUND POLICY V.
EXAMPLE OF POLICY IMPLEMENTATION
- SPECIFIC CASE STUDIES VI.
CONCLUDING REMARKS l
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SLIDE 1
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l Ground Detection System-Description of the Operation in order to understand the effects of different grounding configurations and detection instrument response, the following simphfied analysis has been prepared. ThC electric alarm unit type detection is shown, case A 96 PB 1 p'.
No grounds on the system d
300 kQ
- Soo k O type ground system li e Current in emperes (A) a bettery I
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. No ground detection storm 9
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S LIDE 3
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tL--_______---____________-__-_--_
i Ground Detector Voltage. Resistance Correlation ' for : Action Response n
L.sVfL Level.
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5 Alarm and Action Voltage / Resistance Equivalents Station 125.Vdc System 250.Vdc System Alarm set point (Res )
125 kQ 125 kn 125 kQ 125 kn Action Level 111 (Res.)
20 kn 40 kn Ground detector-Button Button Button Button operation mode Normal pushed pushed Normal pushed pushed Dresden 2 50.V 90 V 120 V 140 V 215 V 245 V
'3 70 V 90 V 120 V 140 V 215 V 245 V La Salle 1 50 V 90 V 120 V 140 V-215 V 245 V 2
50 V 90 V 120.V 50 V~
130 V 195.V Quad Cities 1 & 2 '
70 V 90 V 120 V 140 V-215 V 245 V Byron 1.& 2 70 V 90 V 120 V
.. Braidwood 1 & 2 70 V 90 Y 120 V Zion 1 & 2 70 V 90 V-120 V Note: 1. Dashes (..) mean not applicable.
- 2. The voltage values were rounded off to the nearest 5 volts due to instrument accuracy.
l l
M2475.009 02-89
$1.IUE
_ _ - _ - _ - _ _ = _ _ _ _ _ _ _ _ _ _ _ _. _ _ _ _.
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INTERIM DC GROUND POLICY.
LEVEL I:
PRIOR TO ALARM THRESH 0LD (GREATER THAN,125K OHMS).
ACTION:
IMPLEMENT STATION SPECIFIC POLICY LOCATE AND REMOVE GND AS TIME PERMITS LEVEL II:
ALARM TO 20K OHMS (125K OHMS TO 20K OHMS)
ACTION:
IMMEDIATE ACTION TO LOCATE AND REMOVE GNDS.
- INITIATE WORK REQUEST ON NEXT SCHEDULED SHIFT (B1 PRIORITY)
LEVEL III:
ALARM AND LESS THAN 20K OHMS ACTION:
IMMEDIATE ACTION TO LOCATE AND REMOVE ~GNDS.
- INITIATE WORK REQUEST AND CALL OUT IF-NECESSARY (Al PRIORITY)
- NOTIFY CORP MGT. WITHIN NEXT WORK DAY
- IF THE GROUND WILL PERSIST, ENSURE A DOCUMENTED EVALUATION IS PERFORMED WITHIN 14 DAYS l
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SLIDE #5 w-
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L GBQUND_f0LICY BAS.IS GROUND CL!RB.ERL 125K OHM ALARM SET 1MA
- HFA RELAY " DROP-0UT" 1.25MA HMA RELAY " DROP-0UT" 13.00MA HGA RELAY " DROP-0VT" 0.80MA 20K OHM ACTION LEVEL III 5.68MA
- HFA RELAY " PICKUP" 37.5MA HGA RELAY " PICKUP" 20.5MA HMA RELAY " PICKUP" 13.0MA.
- PREDOMINANT RELAY e
SLIDE #6
- = _ _ - - _ _ _ __.
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a s, EIML_.GMD POLICLEEAEBES I.
ACTION LEVELS' BASED ON +/- PUSHBUTTON READINGS II.
STANDARDIZE CALIBRATION AND. SETTING PROCCDURES III.
LEVEL III ACTIONS A.
WEEKLY CHECK FOR OTHER MASKED GROUNDS BY ISOLATING EXISTING GROUNDS (IF PRACTICAL).
B.-
PERIODIC CHECK OF GROUND CIRCUITS FUNCTIONALITY (IF PRACTICAL)
C.
14 DAYS TO LOCATE & REMOVE GROUND (OR) DOCUMENTED EVALUATION EVALUATION CONSIDERATIONS EQUIPMENT REDUNDANCY NEED FOR TEMPORARY STANDING ORDERS FREQUENCY OF SURVEILLANCE TESTS CORRELATION OF GROUND APPEARANCE WITH OTHER EVENTS SAFETY FUNCTION OF GROUNDED EQUIPMENT AND MITIGATION OF P0TENTIAL FAILURE SIZE OF GROUND CONSIDER RESTRICTION 0F DC MOD TESTING l'
IL SLIDE #9 l
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1988 PRELIMINARY DATA TURNAROUND TIME T0' LOCATE AND REPAIR GROUNDS LESS THAN 125K. OHMS IS ONE DAY SLIDE #11
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