ML20137U382
| ML20137U382 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 01/28/1986 |
| From: | Opeka J NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES |
| To: | Noonan V Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0737, RTR-NUREG-737 A02959, A2959, NUDOCS 8602190155 | |
| Download: ML20137U382 (2) | |
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N UTILITIES o.nor i Ori c.., s,io n sir i. B.,nn. conn.ciicui ty ComessECNd UGret esmD.Oata cowresas
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(203) 66s-s000 k
L January 23, 1986 Docket No. 50-423 A02959 Office of Nuclear Reactor Regulation Attn:
Mr. Vincent S. Noonan, Director PWR Project Directorate #5 Division of PWR Licensing - A U. S. Nuclear Regulatory Commission Washington, D. C. 20555
References:
(1)
- 3. F. Opeka letter to B. J. Youngblood, " Supplement I to NUREG-0737; Safety Parameter Display Sy stem," dated November 26, 1935.
(2)
W. G. Counsil letter to B. J. Youngblood, " Supplement I to NUREG-0737; Safety Parameter Display System," dated December 7,1934.
Dear Mr. Noonan:
Millstone Nuclear Power Station, Unit No. 3 Supplement I to NUREG-0737 Safety Parameter Display System In Reference (1), Northeast Nuclear Energy Company (NNECO) informed the NRC Staff that the Millstone Unit No. 3 Safety Parameter Display System (SPDS) was declared operational on November 8,1935 and that all Phase I SPDS items delineated in Reference (2) had been completed, with the exception of some necessary revisions to the existing status tree setpoints to reflect more current setpoint information received from the. Westinghouse Electric Corporation at that time. These setpoint changes were scheduled for revision and were revised prior to initial criticality.
The purpose of this letter is to provide additional information to the NRC Staf f regarding some aspects of the SPDS that are not fully functional, as discussed during a January 23, 1986 meeting with the NRC Staff. We have determined that the subcriticality critical safety function (CSF) was not fully functional as we had previously reported in that the post-accident neutron monitors were not wired into the SPDS. During our investigation into the lack of post-accident neutron monitoring input into the SPDS, we determined that the wide-range containment pressure inputs were also not wired to the SPDS. The post-accident neutron monitors and the wide-range containment pressure monitors have since been wired into the SPDS and appropriately tested.
Our analysis of this situation has determined that the root cause was the failure to provide direction explicitly to the designers to provide input signals from the post-accident neutron monitors and the wide-range containment pressure monitors to the SPDS. As such, the design as released and constructed did not show these input loops as being required for the SPDS. The verification prdcess L
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.. which was undertaken and completed prior to declaring the SPDS operational was intended to assure that the SPDS was properly installed.
This verification process involved testing the field input loops separately from the SPDS sof tware and displays. The latter was tested during the Integrated Acceptance Test, which utilized simulated input signals since the various ranges of input signals could only be generated by the use of simulation to meet all design functional requirements.
As a result of the above items, actions are being taken to assure that all other SPDS inputs are properly installed and tested. Our investigation, as well as any other necessary corrective action, will be completed prior to exceeding 5% power. Consequently, the SPDS will be fully operational at that time.
In addition to the above items, SPDS setpoints have been revised and appropriately verified correct to reflect recent changes to the setpoints in the Emergency Operating Procedures (EOPs) and the radiation monitoring system.
We have reviewed the above events pursuant to 10CFR50.72 and 10CFR50.73 and have determined them to be not reportable. However, we concluded that NRC Staff notification was appropriate due to our previous notification that the SPDS was operational on November 8,1985.
Should you have any questions, please contact us.
Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY et. al.
BY NORTHEAST NUCLEAR ENERGY COMPANY Their Agent
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- 3. F. Opeka Y
Senior Vice President STATE OF CONNECTICUT )
) ss. Berlin COUNTY OF HARTFORD )
Then personally appeared before me J. F. Opeka, who being duly sworn, did state that he is Senior Vice President of Northeast Nuclear Energy Company, a Licensee herein, that he is authorized to execute and file the foregoing information in the name and on behalf of the Licensees herein and that the statements contained in said information are true and correct to the best of his knowledge and belief.
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