B15326, Provides Supplemental Info to 950428 TS Change Request Re Ultimate Heat Sink
| ML20087B424 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 08/02/1995 |
| From: | Opeka J NORTHEAST NUCLEAR ENERGY CO., NORTHEAST UTILITIES SERVICE CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| B15326, NUDOCS 9508080074 | |
| Download: ML20087B424 (3) | |
Text
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W 107 Seiden Street, Berba, CT 06037 [
h Nortlwast Utihties Service Companyl P.O. Box 270 -
Ilanford, CT 06141-0270 -
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j (203) 665-5000 :
August ~2',
1995 pocket No.- 850-423 B15326
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Re: 10CFR50.90 4
U.S. Nuclear Regulatory Commission Attention:
Document Control Desk Washington, DC 20555-Millstone Nuclear Power Station, Unit No. 3 Proposed' Revision'to Technical Specifications Ultimata Heat S4nk - suppiamentary Information The purpose of this letter is to supplement the-original request made by ' Northeast Nuclear Energy Company (NNECO) on April 28,
- 1995, m regarding the maximum ultimate heat sink (UHS)~ temperature-of 75'F for Millstone ' Unit No.
3.
Millstone Unit No. 3-Technical Specification Limiting condition"for.
Operation (LCO) 3.7.5 specifies a : maximum UHS temperature ' of 75'F.
'To eliminate the potential for~ cycling. plant power level and to provide guidance concerning the action statement associated ~with this LCO, a. proposed Technical Specification chLnge was' submitted to the NRC on. April'28, 1995.
This change requested the addition.
of a 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> UHS. monitoring period to t h o ' a c t i o n. s t a t e m e n t.-
Monitoring will be performed prior'to requiring the plant to be in Hot Standby within six hours and cold Shutdown.within the following 30' hours.- The proposed 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> monitoring period in the LCO action-
' statement is based on-observed ' cyclic. variations in the ' UHS temperature,:and would preclude the need to cycle the plant through a shutdown and startup.
If:the UHS ~ temperature increased above 77"F_ at any time during the 12 hour-monitoring period,.then the
. plant would be required to.be in Hot Standby within the next six hours:and in Cold Shutdown within the_following 30' hours.
NNECO's April 28, 1995, submittal contained'a safety. assessment and it was concluded that the proposed change did not involve' a significant hazards consideration ' (SHC).. This. determination was based on engineering evaluations of-the-limiting ' final safety analysis report (FSAR) Chapter 15 Condition II and III' events l(i~.e., ' loss of offsite power and a steam generator tube rupture
.with AC power available) occurring'during periods of elevated UHS' (1)_
J. L F._ Opeka letter' to the U.S. Nuclear Regulatory Commission,
. " Proposed Revision to Technical Specifications;. Ultimate' Heat-
' Sink," dated April 28,'1995.-
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U.S. Nuclear Regulatory Commission B15326/Page 2 August 2, 1995
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I temperatures.
FSAR Chapter 15 Condition IV events or seismic events were not evaluated because they were not risk significant based on the very low probability of these events occurring during a period of elevated UHS temperature.
Recently, the NRC has requested that NNECO evaluate the ability of the service water system to mitigate the limiting FSAR Condition IV event, the loss of coolant accident, with an UHS temperature of 77'F.
NNECO has performed an evaluation of the service water system loads and has determined that service water can sufficiently cool the loads necessary for safe shutdown with a UHS temperature of 77*F, a loss of coolant accident with or without a loss of normal AC power, and a single active failure.
The evaluation concludes that the available flow to each service water load exceeds the required flow.
The scenario evaluated did not consider a coincident seismic event, as the probability of a seismic event concurrent with a loss of coolant accident, a loss of normal power, and a single active failure during periods of elevated UHS temperatures is so low that it is not considered risk significant.
In summary, NNECO concludes that the addition of a 12 hour1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> time period to monitor the UHS temperature is not an SHC.
An evaluation of the service water system components for all FSAR 15 event scenarios (i.e.,
credible) with a UHS temperature of up to 77*F determined that the safe shutdown capability of the plant is maintained.
Also, an engineering evaluation has concluded that the service water system is capable of performing its accident mitigation function given a 77'F UHS temperature.
As such, the conclusion in NNECO's submittal dated April 28, 1995, that the proposed technical specification change does not involve an SHC, remains unchanged.
We believe the above information, coupled with the information i
provided in our April 28, 1995, submittal, provides a complete f
basis for approval of the requested amendment.
Presently, the average water temperature of the UHS is below 75*F.
However, due to high temperatures experienced this summer, the potential exists for the average water temperature of the UHS to exceed 75*F.
This
)
potential is limited to the months of August and September.
Unfortunately, it is impossible to predict the exact date that the average water temperature of the UHS could be greater than 75*F, since this condition is limited to short-term climatological conditions.
Based on this, NNECO would appreciate NRC review and approval of this request by August 15, 1995.
a y
.l U.S. Nuclear Regulatory Commission B15326/Page 3 August 2, 1995 If the NRC Staff should have any questions or comments regarding l
-this submittal, please contact Mr. R. G. Joshi at (203) 440-2080.
We will promptly provide any additional information the NRC Staff I
may need to respond to this request, and we appreciate your efforts.
in support of this request.
i Very truly yours, NORTHEAST NUCLEAR ENERGY COMPANY FOR: J.
F. Opeka Executive Vice President BY:
e E. A. DeBarba Vice President cc:
T. T. Martin, Region I Administrator V. L. Rooney, NRC Project Manager, Millstone Unit No. 3 P.
D.
Swetland, Senior Resident Inspector, Millstone Unit Nos.
1, 2,
and 3 Mr. Kevin T.A. McCarthy, Director Monitoring and Radiation Division Department of Environmental Protection 79 Elm Street j
P.O.
Box 5066 Hartford, CT 06102-5066 Subscribed and sworn to before me i
this de24 day of h w d,
, 1995 M-I 2
e. o~
DY a Commission Expires:
~
Katnicen T. Gaon Notary Public gWE@kesDecember31.W 1
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