ML19257B283
| ML19257B283 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 01/09/1980 |
| From: | Counsil W NORTHEAST UTILITIES |
| To: | Ziemann D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19257B284 | List: |
| References | |
| NUDOCS 8001150478 | |
| Download: ML19257B283 (4) | |
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January 9,1980 Docket No. 50-245 Director of Nuclear Reactor Regulation Attn:
Mr. D. L. Ziemann, Chief Operating Reactors Branch #2 U. S. Nuclear Regulatory Commission Washington, D. C.
20555 Ref erences.
(1)
D. C. Switzer letter to G. Lear dated March 22, 1976.
(2)
D. C. Switzer letter to G. Lear dated March 30, 1976.
(3) G. Lear letter to D. C. Switzer dated April 2,1976.
(4)
D. C. Switzer letter to G. Lear dated June 9,1976.
(5)
G. Lear letter to D. C. Switzer dated August 6, 1976.
Gentlemen:
Millstone Nuclear Power Station, Unit No.1 Proposed Technical Specification Change for Isolation Condensg Pursuant to 10CFR50.90, Northeast Nuclear Energy Company (NNECO) hereby proposes to amend its operating license, DPR-21, by incorporating the attached changes into the Technical Specifications for Millstone Unit No. 1.
The changes would limit the maximum authorized power level to 40% of full power whenever the Isolation Condenser is inoperable.
The ref erenced letters show that operation at 40% power, without the Isolation Condenser, was extensively reviewed and approved by the NRC in 1976.
References (1) and (2) supplied the justification, resulting in a license condition (not a Technical Specification change) issued by the NRC in Reference (3). This condition restricted power to 40% whenever the Isolation Condenser was inoperable, and allowed continuous operation at 40%.
In an effort to convert the license condition into a Technical Specification, NNECO proposed a two-part Limiting Condition for Operation (LCO) in Reference (4). Part One limited full power operation to 15 days whenever the Isolation Condenser was made or found inoperable. Part Two allowed continuous operation at 40% power if the Isolation Condenser could not be returned to service in 15 days. The NRC Staff review of Reference (4) fully addressed both parts; however, the LCO's issued by the Staff (Reference (5))
omitted Part Two.
Inasmuch as NNECO's submittals and the Staff reviews centered around the 40% limit, we believe it would have been (and is still) appropriate for the Staff to approve Part One as well as Part Two of Reference (4). The purpose of this letter is to propose, again, an LCO allowing continuous operation at 40% power when the Isolation Condenser is inoperable. This proposal will also eliminate the LCO allowing full power operation for 15 days.
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,. In light of post-TMI-2 events, we believe it prudent to take advantage of one of the Lessons Learned:
the significance of core uncovery during accidents and transients. A loss of feedwater and the wcrst single-active failure at Millstone Unit No.1 would result in core uncovery, if operating at 100% without the Isola-tion Condenser. This was reviewed and found acceptable in References (1) through (5), because the primary concern was peak clad temperature (PCT).
It was found that PCT did not go much above 600*F for this limiting transient compared to normal operating fuel clad temperatures of over 700*F.
However, we believe it now prudent to eliminate the LCO allowing 15-day full power operation without the Isolation Condenser, to preclude the chance of any core uncovery. Thus, the changes proposed herein would place the plant in a safer condition than currently allowed by Technical Specifications when the Isolation Condenser is inoperable.
The proposed specifications would also place the plant in an even safer condition than is normally allowed at 100% power, with all ECCS available and the Isolation Condenser available, in terms of core uncovery following an accident or transient.
A summary of the Technical Review and Safety Evaluation performed in-house for this proposed change is attached.
The on-site and off-site review committees (PORC) and (NRB) have reviewed and approved these changes. The changes do not constitute an unreviewed safety question, as defined in 10CER50.59, and as summarized in the attachment.
We have also reviewed this change pursuant to 10CFR170, and have concluded that it involves a Class III type of amendment with a required fee of $4,000.
Accordingly, a check for $4,000 is enclosed for the review and approval of this change to the Operating License.
We wish to point out that the plant has been administratively derated by NNECO, to 40% of full power since January 4,1980 although specifications allow 100% power for 15 days, due to the fact that the Isolation Condenser has been administratively declared inoperable as of January 4,1980.
Specifications now require a cold shutdown in 15 days (by January 19, 1980) unless the Isolation Condenser is declared operable. This specification change would have to be approved by January 19, 1980 if the Isolation Condenser remains inoperable, in order to prevent a cold shutdown. We respectfully request expedited review and approval of the changes proposed herein, prior to January 19, 1980.
Should you have any questions, please contact us.
Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY
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W.' G. Counsil Vice President Attachment i749 552
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Then personally appeared before ine W. G. Counsil, who being duly sworn, did state that he is 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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Notary Public My Commission Ex;!res f,!sch 31,1931 1749 353
NUSCO TECHNICAL REVIEW AND SAFETY EVALUATION Extended Operation of Millstone Unit No. I with I.C. Out Of Service; 40% Power Analysis was performed in 1976 justifying extended power operation of Millstone Unit No.1 at 40% power with the Isolation Condenser (I.C.) system out of service. Those analyses were documented in submittals to NRC dated March 22, 1976, March 30 1976, the NRC Safety Evaluation Supporting Amendment #26 (attached), and NUSCO internal evaluations.
To summarize, derating to 40% power allows the operator at least 10 minutes to initiate manual depressurization of the reactor without uncovering the top of the fuel in the event of a loss-of-all feedwater.
Such a transient is unlikely due to the FWCI sub-system of the feedwater system and has occurred at Millstone only one time in nearly 10 years of operation (that caused by Hurricane Belle and related equipment outages).
Even if manual blowdown were delayed for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br />, peak fuel cladding temperatures would reach only 619 F, compared to normal operating temperatures of over 700*F.
Derating to 40%, therefore, provides for redundant methods of shutdown and cooldown in the event of a loss of feedwater:
first, the FWCI and second, APR plus low pressure systems to reflood.
Either will prevent core water level from dropping below Top-of-Active Fuel (TAF). Therefore, from 40% without I.C., equivalent redundant core protection is available compared to 100% with I.C.
No extra surveillance is required.
Based on studies documented in NED0-24708, August,1979, (Figure 3.1.1.1 -57.6 and 58.6), peak clad temperatures for a typical BWR would not rise much above 600 F even with momentary core uncovery resulting from a similar incident and plant response from full power.
Based on the above, extended operation without the I.C. at 40% power is extremely conservative, more so than the present allowance of 15 days at full power.
The Technical Specification change is administrative in nature in that it allows plant operation in a mode that has been previously analyzed, reviewed, and included in the Millstone Unit No. I licensing bases.
The change reflects a restriction on plant power such that if a loss-of-all feedwater were to occur in conjunction with a loss of the FWCI sub-system, no core uncovery would occur.
The change does not create any new or unanalyzed accidents or malfunctions, does not increase the probability of an accident or malfunction, and does not reduce the margin to safety in any manner. The change does not constitute an unreviewed safety question with respect to 10CFR50.59.
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