ML20213F619
| ML20213F619 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 05/05/1987 |
| From: | Mroczka E NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| Shared Package | |
| ML20213F622 | List: |
| References | |
| B12486, NUDOCS 8705150393 | |
| Download: ML20213F619 (5) | |
Text
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l May 5,1987 Docket No. 50-423 B12486 Re: 10 CFR 50.90 U.S. Nuclear Regulatory Commission Attn:
Document Control Desk Wasnington, D.C. 20555 Gentlemen:
Millstone Nuclear Power Station, Unit No. 3 Proposed Revision to Technical Specification Emergency Diesel Generator Pursuant to 10 CFR 50.90, Northeast Nuclear Energy Company (NNECO) hereby proposes to amend its Operating License, Nf F-49, by incorporating the attached propor,ed changes into the Technical Specifications of Millstone Unit No. 3.
Specifically, the proposed changes to Technical Specification Section 4.8.1.1.2 willincrease the Emergency Diesel Generator (EDG) start-up tu.e of 10 seconds to !! seconds and will increase the response time for item ll.a (for a loss of power) of Table 3.3-5 from 12 to 13 seconds.
Background
The acceptance criterion for Millstone Unit No. 3 EDG start-up time is currently 10 seconds. The EDGs are currently starting in approximately 9.5 seconds, leaving a very small margin for meeting the technical specification limit of 10 seconds. This current acceptance criterion Las resulted in declared diesel failures (10.1 second starting time) on two occasions, resultirg in a special report required per Technical Specifications. It is therefore desired to relax the diesel start-up time to allow 11 seconds for start. While relaxing the EDG start-up time requirement, NNECO plans to maintain the current Engineered Safeguard Features (ESF) response time requirements in Table 3.3-5 of the Millstone Unit No. 3 Technical Specification except item 11.a for a loss of power event without a safety injection signal.
In this case, the 12-second requirement will be increased to 13 seconds.
Safety Evaluation NNECO has reviewed the attached proposed changes pursuant to 10 CFR 50.59 and has determined that they do not represent an unreviewed safety question.
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U.S. Nuclear Regulatory Commission B12486/Page 2 May 5,1987 Effect on Design Basis \\ccident Analysis The accidents which take credit for the ESF functions with an assumed loss of offsite power include:
Main Steamhne Rupture (FSAR Section 15.1.5)
Loss of Normal Feedwater (FSAR Section 15.2.6)
Feedline Rupture (FSAR Section 15.2.3)
Steam Generator Tube Rupture (FSAR Section 15.6.3)
Large Break Loss of Coolant Accident (FSAR Section 15.6.5)
Small Break Loss of Coolant Accident (FSAR Section 15.6.5)
LOCA Mass and Energy Release (FSAR Section 6.2.1)
)
Small and Large Break LOCA l
I In performing large and small break loss of Coolant Accident (LOCA) analyses, the diesel start-up time is not modeled explicitly. Rather, a step function is assumed for safety injection (SI) flow delivery consistent with the total ESF response times contained in Table 3.3-5 in the Technical Specification. These response times are assumed not to change. The ESF functions in Table 3.3-5 which include EDG start-up time allowan es and that are modeled in the LOCA analyses include SI on pressurizer low pressure and Si on containment HI-l pressure. Contcinment sprays are modeled to start at the earliest possible start time since that is conservative for LOCA Apperdix K calculations. Therefore, this rebxation of the EDG start-up time requirement will have no impact on the large or small break LOCA analyses performed for Millstone Unit No, 3.
The current results presented in the FSAR remain applicable.
Non-LOCA Transients The proposed change to the Technical Spccification will only have potential Impact on non-LOCA accidents that involve actual analyses of cases with loss of offsite power. The specific non-LOCA accidents that need to be considered are the steamline break, loss of normal feedwater/ loss of offsite power and the feedline break. The area of concern for each of these transients is whether the proposed response time change will delay Si and/or auxiliary feedwater flow (AFW) to the extent that the conclusions in the FSAR are impacted.
With respect to AFW,it is noted that the model used in LOFTRAN for analyzing the subject accidents treats AFW flou as a step function. It is either on or off with no gradual ramp from zero to full flow being considered. As a result, the only ccncerns are the total amount of AFW flow and the timing cf its initiation or termination. The proposed Technical Specification change will not impact either of these items. For the loss of normal feedwater/ loss of of fsite power, Si is not an issue of concern.
Therefore, concluding that the Technical Specification change will not impact the AFW model implies that the change will also not affect the FS \\R conclusions for this accident.
For the steamline break accident, the primary concern with respect to Si initiation relates to whether sufficient boron is provided to the Reactor Coolant System (RCS) in time to control or preclude any return to power resulting from a cool-down transient. For the feedline break with loss of of fsite power, the
U.S. Nuclear Regulatory Commission B12486/Page 3 May 5,1987 primary function of the SI flow is to provide cooling to the RCS. For both these accidents, it is noted that the cases without offsite power are not limiting and that substantial margin exists to design limits.
Further, the Technical Specification change under consideration will not alter either the time at which full SI flow is initiated to the RCS or the amount of that flow, which are the critical parameters. Therefore, the proposed change in the EDG start-up delay t?me will not have a significant adverse effect on the safety analysis results for the steamline break or feedline break accidents. The conclusions of the FSAR therefore remain valid.
SGTR/LOCA Mass and Energy It is assumed that the proposed change in the response time from 10 to 11 seconds for the EDG start-up time does not change the total response time for Si initiation. On this basis, the change does not impact the analysis for a steam generator tube rupture (SGTR) or the calculation of the LOCA mass and energy releases for Millstone Unit No. 3, and thus the conclusions in the FSAR regarding the SGTR analysis and the containment integrity evaluation for a
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LOCA remain valid.
Potential for Creation of an Unanalyzed Accident There are no rew failure modes associated with these proposed changes, as no 4
design changes have been made. The relaxation of the EDG start-up time does not create the possibility of an accident or malfunction or a different type than any evaluated previoutly in the safety analysis report.
Ef fect on the Margin of Safety Since t!'e response time for all ESF functions will be met, there is no impact on the basis of the technical specification. Therefore, these changes do not reduce the margin of safety as specified in the basis of any technical specification.
Summary and Conclusions l
Based on the foregoin5 assessment, the changes proposed herein are considered safe and do not represent an unreviewed safety geestion as defined in 10 CFR 50.59 since they do not:
1.
Increase the frequency of occurrence or the consequences of an accident or malfurction of equipment important to safety previously evaluated in the safety analysis report; 2.
Create the possibility of an accident or malfunction of a different type than any evaluated previously in the safety analysis report; 3.
Reduce the margin of safety as defined in the basis for any technical specification.
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U.S. Nuclear Regulatory Commission BIN 6/Page 4 Mt.y 3,1987 Significant Hazards Consideration In accordance with 10 CFR 50.92, NNECO has reviewed the attached 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 10 CFR 50.92(c) are not compromised; a conclusion which is supported by our determinations made pursuant to 10 CFR 50.59. The proposed changes do not involve a significaat hazards consideration because these changes would not:
1.
Involve a significant increase in the probability or consequences of an accident previously evaluated. As stated above, the increased allowance for EDG delay is incorporated in the total ESF response time. Since the total ESF response time shown in Table 3.3-5 of the Millstone Unit No. 3 Technical Specifications is assumed not to change, the current safety analyses remain applicable. In addition, the probability of an accident is not significantly increased since operation of the EDG is assumed af ter a design basis accident coincident with a loss of offsite power.
2.
Create the possibility of a new or different kind of accident from any previously evaluated. The relaxation of the EDG start-up time does not create the possibility of an accident or malfunction of a different type than any evaluated previously in the safety analysis report. No design changes Fave been made to the EDG; therefore, no new failure modes are introduced.
3.
Involve a significant redaction in a margin of safety. As stated abote, the overall ESF response times are not assumed to change and the conclusions of the current safety analyses are nill applicable. Thus, the the safety limits will still be met.
Moreover, the Commission has provided guidance concerning the application of standards in 10 CFR 50.92 b) providing certain examples (March 6,1986, F_R, 7751) of amendments that are considered not likely to involve sig,nificant hazards consideration. Although the proposed changes herein are not enveloped by a specific example, the proposed changes would not involve a significant incrv.se in the probability or consequences of an accident previously analyzed.
The proposed changes will increase the EDG start-up time resulting in an added margin between actual measured EDG start-up time and tSe technical specification rcquirement. The results of the safety evaluation show that the s:,fety analyses remain applicable since the total delay time for the ESF's actuation is assumed not to change. Therefore, the proposed changes would not involve a significant hazards consideration.
Based upon the information containad in this sut mittal and the NRC final environmental assessment for Millstane Unit No. 3, NNECO has concluded that, pursuant to 10CFR31, there are no signilicant radiological or ncn-radiological impacts associated with the proposed action and that the proposed license amendment will not have a significar.t effect on the quality of the human environment.
The Millstone Unit No. 3 Nuclear Board has reviewed and approved the attached proposed revision and concurs with the above determinations.
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U.S. Nucl:ar Regulatory Commission B12486/Page 5 May 5,1987 In accordance with 10 CFR 50.91(b), NNECO is providing the State of Connecticut with a copy of this proposed amendment.
Pursuant to the requirements of 10 CFR 170.12(c), enclosed with this amendment request is the application fee of $150.00.
Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY r
Nvd E.J.))fo'zka
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c Senlof Vice President cc:
Revin McCarthy Director, Radiation Control Unit Department of Environmental Protection Hartford, Connecticut 06116 W. T. Russell, Region I Administrator
- 3. T. Shediosky, Resident inspector, Millstone Unit No. 3 R. L. Ferguson, NRC Project Manager, Millstone Unit No. 3 STATE OF CONNECTICUT )
) ss. Berlin COUNTY OF HARTFORD
)
Then persoaally appeared before me E. 3. 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 a+d belief.
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