ML20133K947
| ML20133K947 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 08/06/1985 |
| From: | Boyer V PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | Butler W Office of Nuclear Reactor Regulation |
| References | |
| CON-#385-178 OL, NUDOCS 8508120430 | |
| Download: ML20133K947 (5) | |
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PHILADELPHIA ELECTRIC COMPANY 2301 MARKET STREET P.O. BOX 8699
)
PHILADELPHIA, PA.19101 (21st e4i.4 soo AUG 6 1985
- v. s. so y en SR. VICE PRESIDEN T NUCLE AR POWE R 4
Walter R. Butler, Chief Docket Nos. 50-352 4
Licensing Branch No. 2 50-353 U.S. Nuclear Regulatory Conmission Washington, D.C.
20555
SUBJECT:
Limerick Generating Station, Units 1 and 2 I
Dear Mr. Butler:
i On August 1, 1985, discrepancies were noted by an NRC Region I l
Inspector between the sequence of events observed in a simulated loss of AC power event and the sequence of events that are described for such events in Limerick FSAR Section 15.2.6, Loss of AC Power.
Specifically, main steam isolation valve (MSIV) closure did not occur 3
l within 2 seconds of event initiation in the simulation as asststed in the FSAR analyses.
Although the Limerick plant simulator studies, which initiated the inspector's concern were performed in support of testing at approx-Imately 25% power and were not, therefore, directly ccrnparable to the FSAR analyses, Philadelphia Electric Ccrnpany's investigation J
determined that the sequence of events listed in FSAR Tables 15.2-9 and 15.2-10 were not representative of the expected plant response because of certain Limerick unique design features.
)
Our investigation revealed that design changes to enhance the rollability of the reactor protection system (RPS) power supply were not reflected in the existing loss of AC power transient analyses. The Limerick design provides the RPS with an uninterruptable power source Instead of the standard AC driven motor-generator set. With this enhanced design, the RPS will not cause MSIV closure upon the loss of 4
AC power as is the case with the standard design, i
l It was further recognized that loss of one or two of Limerick's three auxiliary power transfonners would not result in a loss of auxillary power. However, the simultaneous loss of all three auxillary transfonners would result in the loss of all auxillary power. This I
event is identical to the event " Loss of All Grid Connections" which has been reanalyzed for Limerick as described below. This reanalysis directly addresses the guidance of tOREG-0800, Section 15.2.6.
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8508120430 850006 PDR ADOCK 05000352 l l 0
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- Using the ODYN code, General Electric reanalyzed the " Loss of All Grid Connections" event at full power using Initial conditions and other nodel inputs that reflect the Limerick as-built design.
The results of the reanalysis are shown on the attached Table I and are compared to the original " Loss of All Grid Connections" transient analysis, the original " Loss of Auxiliary Power Transforner" transient analysis and the similar, but more limiting, " Load Rejection Without Bypass" transient results (Section 15.2.2).
The ODYN reanalysis showed that all paraneters renalned bounded by other nore severe transients.
For this reason, the " Loss of All Grid Connections" transient does not provide any unique or extraordinary challenges to the Lincrick reactor systens beyond those previously evaluated and found acceptable.
To address a concern that errors might exist elsewhere in Chapter 15 in spite of existing procedural controls governing content of and changes to the FSAR, a detailed review of Chapter 15 was initiated.
This review utilized a nunber of different teans:
A multi-disciplined team of PECo systan engineers.
A tean of Senior Licensed Operators at the plant.
A tean of system and licensing engineers at Bechtel, the plant architect-engineer.
A General Electric tean of engineers and analysts familiar with both Limerick and Chapter 15 analyses.
Each team reviewed the event descriptions and analysis results in Chapter 15 fran its unique perspective for proper application to Limerick. Any concerns were resolved through further investigation or discussion with the responsible organization.
In no case were any additional sequences or analysis results found to be inappropriate for Limerick.
The overall results of the review Indicated that the error in Section 15.2.6 was an isolated case.
Further, they confirned that the analyses in FSAR Chapter 15 are appropriate for Limerick, that the expected response of Limerick to the Chapter 15 transients and accidents is bounded in each case by the analysis, that this chapter provides the required support for the Technical Specifications, and that Limerick continues to comply with all applicable NRC regulations and licensing conmitrents.
Changes to FSAR Sectlon 15.2.6 and associated tables and figures which incorporate the results of the reanalysis described above will be formally incorporated into the FSAR in the next revision, scheduled for Septonber,1985.
In addition, that revision will include similar changes to Section 15.9, which serves as a review aid for the ranalnder of Chapter 15.
. Should you require any additional Information In this regard, please do not hesitate to call.
Sincerely, a
Copy to: (See Attached Service Lint)
FOH/dg/08068501
cc: Judge Helen F. Hoyt Judge derry Harbour Judge Richard F. Cole Troy B. Conner, Jr., Esq.
Ann P. Hodgdon, Esq.
Mr. Frank R. Romano Mr. Robert L. Anthony Ms. Phyllis Zitzer Charles W. Elliot, Esq.
Zort G. Ferkin, Esq.
Mr. Thomas Gerusky Director, Penna. Emergency Management Agency Angus R. Love, Esq.
David Wersan, Esq.
Robert J. Sugannan, Esq.
Kathryn S. Lewis, Esq.
Spence W. Perry, Esq.
Jay M. Gutierrez, Esq.
Atcmic Safety & Licensing Appeal Board Atcmic Safety & Licensing Board Panel Docket S Service Section Mr. James Wiggins Mr. Timothy R. S. Campbell
e TABLE I LIMERICK GENERATING STATION SELECTED FSAR CHAPTER 15 TRANSIENT ANALYSES Max Max Max Max Max Core Neutron Done Vessel Steam 1Ine Any Surface Blowdown Flux Press Press Press Heat Flux Duration Event
(% NBR)
(psIg)
(psIg)
(psIg)
% of initial (sec)
EXISTitE FSAR ANALYSES
- Loss of Auxiliary Power 104.3 1180.0 1194.0 1179.0 100.1 7.5 Transformer (FSAR Section 15.2.6.1.1.1)
- Loss of All Grid Connections 109.3 1173.0 1190.0 1169.0 100.0 11.6 l
(FSAP Section 15.2.6.1.1.2)
REVISED FSAR NiALYSIS l
- Loss of All Grid Connections 178.5 1168.4 1175.4 1164.2 101.3 4.8 l
(ODYN Reanalysis)
BOUPOffE REFEP.ENCE CASE
- Generator Load Rejection 222.5 1200 1225.0 1196.0 106.2 12.7 w/o Bypass (FSAR Section 15.2.2.2.1.2)
HDH/dg/08068502
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