ML20115D905
| ML20115D905 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 10/16/1992 |
| From: | Helwig D PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| IEB-88-007, IEB-88-7, NUDOCS 9210210220 | |
| Download: ML20115D905 (3) | |
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PHILADELPHIA ELECTRIC COMPANY LIMEMCK GENERATING STATION P. O. BOX 2300 SANATOGA, PA 19464-2309 October 16, 1992 (215) 327-1200, EXT. 3000 Docket Nos.
50-352 50-353 DAVID R. HELWIG License Nos. NPF-39 LIMERCK GE EP IN STADON U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555
SUBJECT:
Limerick Generating Station, Units 1 and 2 Reply to a Notice of Deviation NRC Inspection Report Nos.
50-352/92-21 and 50-353/92-21 Attached is Philadelphia Electric Company's reply to a Notice of Deviation for Limerick Generating Station (LGS) Units 1 and 2, which was co.;tained in the NRC Inspection Report Nos. 50-352/92-21 and 50-353/92-21 dated September 18, 1992.
The Notice of Deviation identified an apparcnt deviation from commitments made in respense to NRC Bulletin No. 88-07 Supplement 1,
" Power Oscillations in Boiling Water Reactors
( dWRs), " dated December 30, 1988, which dealt with core thermal hydraulic instabilities.
The attachment to this letter provides a restatement of the deviation followed by our response.
If you have a:"i questions or require additional information, please contact us.
Very truhr yours, 8,
JLP:cah Attachment cc:
T.
T.
Martin, Administrator, Region I, USNRC T. J.
Kenny, USNRC Senior Resident Inspector, LGS I
9210E'.022d 921016
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PDR f
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Attachment Page 1 of 2 Docket Nos. 50-352/92-21
, 353/92-21 Reply to a Notice of Deviation Restatement of the Deviation During an NRC examination' conducted from July 20 through July 29, 1992, a-deviation from your written: commitments made in response to NRC Bulletin No. 88-07, Supplement 1, was identified.
In accordance with'the, " General Statement of folicy and-Procedure _for NRC Enforcement Actions," 10 CFR Part 2, Aptendix C (1992), the deviation-is listed below:
In response to NRC Bulletin-No 88-07, Supplement 1, licensee-l letter dated March 7, 1989, states that Philadelphia Electric Co,cany cammitted that the General Electric interim stability recommendations were completed and-implemented for-Limerick Unit I and would be used for the operation of Unit 2.
The follow'ng-l conditions for evidence of thermal hydraulic instabilities were j
incorporated into the approved plant procedures:-
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" Average power 1 range monitor (APRM) peak to peak
-oscillations greater than,10% or periodic local power i
range monitor (LPRM) upscale or downscale alarms in addition to the guidance provided in Elt, 380, Revision 1."
Contrary to the above, Procedures OT-104,
" Unexpected / Unexplained Reactivity Insertion," and OT-112,
" Recirculation Pump Trip,"
were revised on June 12, 1992, suc that it substantially changed so AFaM peak to peak oscillations greater than 10% or periodic LPRM upscalelor downscale alarms are 4
not now considered-evidence of instability.-
l
, RESPONSE Philadelphia Electric Company (PECo) has-determined.that no deviation from commitments made in response-to NPC Rulletin No.
l 88-07 Supplement 1 exists.
The' revision to plant operating procedures, including OT-104
-and OT-ll2, on June 12, 1992,- further reduced the threshold: for operator response to an oscillation eventLand enhanced the detection ard avoidance guidance.
Our, response:to Bulletin No.-
88-07, Supplement 1 was based on Ge1eral Electric interim stabil'ity corrective action recommendations.
.As more information became available from investigations into core-thermal hydraulic instability, we adopted the more-conservative Boiling Water'
- Reactor Owners Group -(BWROG) recommendata.on contained in BWROG letter BWROG-92030 dated March 18, 1992, "lmplementation Guidance t
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-Page'2 oi 2
- Docket Nos. 50-352/92-211 50-353/92-21
~ for Stability. Interim Corrective. Actions."
Procedures OT-104 and OT-112_were-revised to incorporate the following BWROG-92030 1
H recommended conditions for evidence of_ thermal hydraulic instabilities:
4 1.
Any.LPRM or APRM noise signal grows by two or more times it-initial noise level, i
2.
The characteristic of the-LPRM and APRM sj:me'a change from.
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random to a regular periodic variation-(w th apps ximately 1 to 2 second oscillation period).
3.
Period meters display strong, positive to negative swings (with approximately 1 to 2 second oscillation 7 period).
As a result of the revision to procedures OT-104 and OT-112, i
operators are expected to initiate alscram well before APRM-peak-to. peak oscillations-:xceed 10% or LPRM upscale'or downscale j
alarms are received.
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- Furthermore, the NRC staff has reviewed BWROG-92030, which is'the basis for the current procedural-guidance. - In a September 17, 1992, Nuclear Reactor Regulati.on staff presentation to-f,he l
Advisory Committee.~or ReactorLSafeguards the staff discussed the imminent issuance of an Information' Notice which'will endorse' BWROG-92030 precautions.
1 in summary, no deviarion from commitmenta made in response to NRC Bulletin No. 88-07, Supplement 1 exists because the commitments
'iade are Lounded by the guidance.in the cvrrent revisions to plant operating procedures, including OT-104tand OT-ll2.
APRM' 2
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peak to peak oscillations greater than-10%~or periodic'LPRM upscale or dowascale alarms are still' considered evidence of instabil-ity.
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