ML20035H739
| ML20035H739 | |
| Person / Time | |
|---|---|
| Issue date: | 07/07/1992 |
| From: | Newberry S Office of Nuclear Reactor Regulation |
| To: | Hijeck P ABB COMBUSTION ENGINEERING NUCLEAR FUEL (FORMERLY |
| References | |
| NUDOCS 9305060373 | |
| Download: ML20035H739 (4) | |
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July 7, 1992 Paul Hijeck ABB Combustion Engineering 1000 Prospect Hill Road Windsor, Connecticut 06095-500 CEP9423-408 Dear Mr. Hijeck
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION IN SUPPORT OF THE STAFF REVIEW OF TOPICAL REPORT CEN-403, "ESFAS SUBGROUP RELAY TESTING" DATED JULY 1991.
Enclosed is a list of general questions and requests for clarification for the referenced topical report. The staff has concluded that the requested additional information will be necessary to complete the review.
When you l
have resolved these questions and developed a response, I would like to i
propose a meeting to discuss this topical report.
Original signed by; Scott Newberry, Chief Instrumentation and Control Systems Branch Division of Systems Technology Office of Nuclear Reactor Regulation
Enclosure:
List of general questions cc w/ enclosure:
A. Thadani DISTRIBUTION Central File /PDR3 SICB R/F CDoutt JMauck SNewberry SICBgy OFC SICB SICB SN,ddberry NAME CDoutt:bp*
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DATE 7/01/92 7/01/92 f/
/92 OFFICIAL RECORD COPY Document Name:
9305060373 920707 DR TOPRP EMVC l
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SUBJECT:
REQUEST FOR ADDITIONAL INFORM?. TION CEN-403, SUBGROUP RELAY TEST INTERVAL EXTENSION," JULY 1991 The staff has reviewed the report CEN-403, "ESFAS Subgroup Relay Test Interval Extension," dated July 1991, issued by the 1
Combustion Engineering Owners Group (CEOG) and has concluded that additional information will be necessary in order to complete the review.
The information needed by the staff is detailed below:
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l 1.0 NRC INFORMATION NOTICE 92-04 l
1.1 STATEMENT Although not referenced by CEN-403, NRC Information Notice 92-04,
" Potter & Brumfield Model MDR Rotary Relay Failures," dated l
January 6, 1992, is pertinent to both the Report and the staff's review of the Report.
NRC Information Notice 92-04 described extensive changes that l
l were made to the MDR relay starting.in October 1985 and finishing I
in May 1990 and contained the statement "P&B and implemented all l
these modifications to its MDR rotary relay design by May 1990."
The Information Notice then described events occurring after May 1990, at General Electric (GE) supplied nuclear power plants that The Information Notice appear to be failures of the MDR relay.
went on to note that:
"While each of the MDR relays failed between 1 month to 13 years after it was placed in service, most failed within 2 to 5 years."
This statement covers the May 1990 modifications.
1.2 OUESTIONS
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Do the "new" relays mentioned in CEN-403 contain the 1.2.1 modifications that are described in NRC Information Notice 92-04 and completed by May 1990?
The Information Notice also noted MDR relay failures that have occurred after May 1990.
NRC Information Notice 92-04 reported on failures of MDR 1.2.2 relays at nuclear power plants other than those supplied by Combustion Engineering (CE).
CEN-403 attempted to establish the reliability of the MDR relay using the operating history from 13 CE supplied operating nuclear plants.
Is this valid?
Would not CEN-403 be more representative of the MDR reliability if it had taken into account MDR relay failures within the safety systems of all operating nuclear power plants?
In as much as NRC Information Notice 92-04 and CEN-403 1.2.3
i l' discuss the same subject, i.e.,
the reliability of the MDR relay, how did the CEOG resolve the concern of NRC l
94-04 prior to the issuance of CEN-403?
2.0 CEN-403 2.1 STATEMENT The MDR rotary relay is currently used in the safety related systems of nearly all currently licensed and operating nuclear power plants.
The purpose of CEN-403 is to justify extending the Surveillance Test Interval for the ESFAS subgroup relays used in CE plants.
2.2 OUESTIONS What is the period of time covered by the data contained 2.2.1 in Table 1 and analyzed in Section 4.0 of Cen-403?
"pelay Information Summary," are the NP Table 1, 2.2.2 failures included in the MR failures or should they both be added to the total failures to be taken into account?
Was any of the failure data based on the New P&B relay?
2.2.3 j
The Report appears to assign to the relays, even relays 2.2.4 from different manufacturers, the same degree of reliability.
Explain.
2.2.5 Doesn't the lack of records from Arkansas 2 and i
Waterford 3 cloud the analysis?
Are the relays at these two plants old or new or a combination of both?
2.2.6 Also, doesn't eliminating Maine Yankee and Palisades from the analysis skew the analysis?
This has the
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effect of reducing sample size and appears to eliminate many relay malfunctions from the analysis.
It also appears that Maine Yankee and Palisades would benefit from a staff approval of the Report without having their respective plant relay operating history analyzed.
Why wasn't the SONGS 2, 3 relay data used?
It appears 2.2.7 that six of the possible worst offenders were eliminated from the analysis.
What is the total number of relays used in the safety 2.2.8 systems of the CE plants that are not testable at power?
Table 1 shows no data from the New P&B relays being used 2.2.9 in the analysis yet on Page 9, last paragraph, phrase
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_3 starting with " failures on the new model relays" indicates that the New P&B relay data was used.
For the various relays referenced in CEN-403 why was the 2.2.10 reliability study restricted to just CE applications?
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