ML20117C750
| ML20117C750 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 04/30/1985 |
| From: | Counsil W, Opeka J NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES |
| To: | Murley T, Youngblood B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I), Office of Nuclear Reactor Regulation |
| References | |
| F0436A, F436A, SD-45, NUDOCS 8505090521 | |
| Download: ML20117C750 (2) | |
Text
.
NORTHEAST UTILITIES o.nor i 0,,,c... s.io.n si,..i. B.,nn. conn.ci,ce 2,70[.Y.N'7,7.'*7 P.O. BOX 270
~j,*', **j,'['*'"[*i,,,,
HARTFORD. CONNECTICUT 06141-0270 y
k k
J (203) 66s-s000
.u,,
.s. m.
.. co...
April 30,1985 Docket No. 50-423 F0436A Dr. Thomas E. Murley Regional Administrator Region i U. S. Nuclear Regulatory Commission 631 Park Avenue King of Prussia, PA 194'06 Mr. B. J. Youngblood, Chief Licensing Branch No. I Division of Licensing U. S. Nuclear Regulatory Commission Washington, D. C. 20555
References:
(1)
W.
G.
Counsil to T.
E.
- Murley, B10950, dated November 16i 1983.
(2)
B. J. Youngblood to W. G. Counsil, Safety Evaluation Report (SER) Related to the Operation of Millstone Nuclear Power Station, Unit No. 3 (NUR EG-1031), dated July,1984.
Gentlemen:
Millstone Nuclear Power Station, Unit No. 3 Reporting of Potential Significant Deficiencies in Accordance with 10 CFR 50.55(e):
Emergency Generator Load Sequencers (SD-45)
In an October 17, 1983 telephone conversation between your Mr. J. Robertson and our Mr. J. J. Festa, Northeast Nuclear Energy Company (NNECO) reported a potential significant deficiency in the construction of Millstone, Unit No. 3 as required by 10 CFR 50.55(e).
The potential significant deficiency involved emergency generator load sequencers supplied by Vitro Laboratories.
It was discovered that for Safety injection Signal (SIS) and. Containment Depressurization Actuation (CDA) signal conditions, the sequencers could f ail to provide the required time delay prior to sequencing. This is d6e to resets which were omitted from the automatic test feature. The primary purpose of the sequencers is to automatically control the loading of the safety related buses when a loss of offsite power has occurred and the buses are being re-energized by the emergency diesel generator, and to automatically control the loading of equipment required for emergency situations which do not involve a loss of of fsite power.
/-Af 8505090521 850430 JM PDR ADOCK 05000423 S
pon
a o ~
We completed our evaluation and determined that these potential time delays could cause problems for the recirculation pumps. Recirculation pump start is designed to delay for all situations. This deficiency could result in a time delay of essentially zero if the input occurrence coincides with the automatic test
'timidg. Mis-timing and premature start of the recirculation pumps could result in the pumps having inadequate net positive suction head (NPSH) resulting in cavitation and possible damage to the pumps.
Hence, this represents a significant deficiency in the final design of Millstone Unit No. 3.
Vitro Laboratories provided a design modification package to correct this significant deficiency which was reviewed and approved by our engineering staff.
These modifications were incorporated into the sequencers and tested at Millstone Unit No. 3.
However, during this testing of the sequencers, it was discovered that a similar problem existed for time delays under Loss of Power (LOP) conditions. This additional concern was reported to your M r.
T.
Rebelowski by our Mr. G. M. Olsen on January 21,1985.
Vitro Laboratories amended their design package to include a modification to correct this deficiency for LOP conditions. This modification was incorporated into the sequencers and, along with the other modifications, successfully tested at Millstone Unit No. 3.
This item was also the subject of Millstone Unit No. 3 SER Confirmatory item No. 40, Section 7.3.3.13 (Reference 2). We consider this report sufficient to resolve this confirmatory item.
We consider this to be our final report for SD-45. We trust that the above information satisfactorily responds to your concerns.
Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY id. GO W. G. Counsil Senior Vice President A E duA v
By: J.F @ ka Vice President cc:
Mr. R. C. DeYoung, Director Division of Inspection and Enforcement U.@. Nuclear Regulatory Commission Washington, D. C. 20555 Mr. fl. C. Li instrumentation and Col. trol Systems Branch U. S. Nuclear Regulatory Commission Phillips Building 7920 Norfolk Avenue Bethesda, MD 20814 a
--