ML20149J245
| ML20149J245 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 02/18/1988 |
| From: | Mroczka E NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| Shared Package | |
| ML20149J248 | List: |
| References | |
| B12815, NUDOCS 8802220327 | |
| Download: ML20149J245 (3) | |
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e EE General Offices
- Seiden Street. Berlin. Connecticut HhRTF RD CONNECTICUT 06141-0270 L
t T; r r,'. % "J # 4" (2cv ces-som February 18, 1988 Docket No. 50-423 B12815 Re:
V.S. Nuclear Regulatory Commission l
Attn: Document Control Desk Washington, D.C. 20555 Gentlemen:
Millstone Nuclear Power Station, Unit No. 3 Proposed Revision to Technical Specifications Reactor Coolant System - Overoressure Protection Systems Pursuant to 10CFR50.90, Northeast Nuclear Energy Company (NNECO) hereby proposes to amend its Operating License, NPF-49, by incorporating the changes identified in Attachment 1 into the Technical Specifications of Millstone Unit No. 3.
Specifically, the proposed changes to Technical Specification Section 3.4.9.3 will change the minimum Reactor Coolant System (RCS) vent area required for cold overpressure protection from 7.0 to 5.4 square inches.
In addition, changes to Technical Specification Sections 3.8.1.2, 3.8.2.2 and 3.8.3.2 are proposed to make them consistent with Section 3.4.9.3 and are considered to be administrative in nature.
Discussion The current Technical Specification Section 3.4.9.3 necessitates the removal ef both Power Operated Relief Valves (PORVs) to meet the required vent area.
The proposed changes would satisfy the Technical Specification requirement by removing only one PORV.
The design basis cold everpressure transients are mitigated by the operation of one PORV (see FSAR Section 5.2.2.11.2).
The original value of 7 square inches in Technical Specification Section 3.4.9.3 was selected to ensure that one PORV would be removed from available vent area.
There was an error in this original selected value.
The cross-sectional area of the piping for each PORV is 5.4 square inches (pipe outside diameter 3.5 inches, wall thickness 0.438 inches).
The required equivalent vent area to mitigate the design basis cald overpressure transients is approximately 2 square inches.
The 5.4 square inches is well in excess of the minimum design basis requirements. Therefore, the requirement to vent the RCS through a 7 square inch hole is overly restrictive.
The proposed changes will reduce the vent size to a more reasonable value and allow the Technical 0g Specification to be met by removing only one PORV.
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U.S. Nuclear Regulatory Commission B12815/Page 2 February 18, 1988 Sionificant Hazards Consideration In accordance with 10CFR50.92, NNEC0 has reviewed the proposed changes and has concluded that they do not involve a significant hazards consideration.
The basis for this conclusion is that the three criteria of 10CFR50.92(c) are not compromised.
The proposed changes do not involve a significant hazards consideration because the changes would not:
1.
Involve a significant increase in the probability or consequences of an accident previously evaluated.
The proposed changes lower the minimum required vent area to that of the pipe for each PORV.
The design basis cold overpressure protection transients are mitigated by the operation of one PORV.
The cross-sectional area of the piping for each PORV is 5.4 square inches. This area is more than sufficient to provide the required flow rate for cold overpressurization events.
Therefore, the use of an equivalent 5.4 square inch vent will not impact the consequences of the cold overpressure transients.
The changes only modify the minimum required vent size for cold overpressure protection transients.
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Therefore, the changes will not affect the probability of failure of this system.
Therefore, the proposed changes do not involve an increase in the probability or consequences of an accident previously evaluated.
2.
Create the possibility of a new or different kind of accident from any previously evaluated.
The proposed changes lower the minimum required vent area while still keeping it larger than that assumed in the design basis analysis.
Therefore, plant response is not modified to the point when it can be considered a new accident.
There are no new failure modes associated with the proposed changes.
Therefore, the proposed changes do not create the possibility of an accident or malfunction of a different l
type than any evaluated previously in the safety analysis report.
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3.
Involve a significant reduction in a margin of safety.
Since the I
proposed changes do not affect the consequences of an accident previously l
analyzed, there is no reduction in a margin of safety.
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Moreover, the Commission has provided guidance concerning the application of I
standards in 10CFR50.92 by providing certain examples (March 6,1986, FR7751) of amendments that are considered not likely to involve a significant hazards l
j consideration.
Although, the proposed changes herein are not enveloped by a i
specific example, the proposed changes would not involve a significant l
increase in the probability or consequences of an accident previously analyzed.
As stated earlier, the changes proposed herein only modify the minimum required vent area to that of the pipe from the pressurizer to the PORV.
This area is greater than the equivalent vent crea of the PORV.
l Therefore, it is concluded that previously analyzed accidents are not i
affected.
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U.S. Nuclear Regulatory Commission B12815/Page 3 February 18, 1988 Based upon the information contained in this submittal and the environmental assessment for Millstone Unit No. 3, these are no significant radiological or non-radiological impacts associated with the proposed action, and that the proposed license amendment will not have a significant effect on the quality of the human environment.
The Millstone Unit No. 3 Nuclear Review Board has reviewed and approved the attached proposed revisions and has concurred with the above determinations.
In accordance with 10CFR50.91(b), we are providing the State of Connecticut with a copy of this proposed amendment.
Pursuant to the requirements of 10CFR170.12(c), enclosed with this amendment request is the application fee of $150.00.
Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY Y$bwdi /
E.7/Mroczkap Sen1or Vice President Attachment cc: Kevin McCarthy Director, Radiation Control Unit Department of Environmental Protection Hartford, Connecticut 06116 W. T. Russell, Region I Administrator R. L. Ferguson, NRC Project Manager, Millstone Unit No. 3 W. J. Raymond, Senior Resident inspector, Milistone Unit Nos. 1, 2, and 3 i
STATE OF CONNECTICUT )
) ss. Berlin COUNTY OF HARTFORD
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Then personally appeared before me E. J. Mroczka, 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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