ML20003H174
| ML20003H174 | |
| Person / Time | |
|---|---|
| Site: | Millstone  |
| Issue date: | 04/28/1981 |
| From: | Counsil W NORTHEAST NUCLEAR ENERGY CO. |
| To: | Crutchfield D Office of Nuclear Reactor Regulation |
| References | |
| TASK-02-03.C, TASK-2-3.C, TASK-RR A01452, A1452, NUDOCS 8105050269 | |
| Download: ML20003H174 (5) | |
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e NOR'ITIEAST UTIIJTIES g,i P.o. Box 270 weca.wcwio a epowe.amaaw UsN N5EsN Ec HARTFORD. CONNECTICUT 06101
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Docket No. 50-245 3
A01452
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Director of Nuclear Reactor Regulation 4,/
Attn: Mr. Dennis M. Crutchfield, Chief g
9 Operating Reactors Branch #5 U. 3. Nuclear Regulatory Commission Washington, D.C.
20555 Ref
- es:
(1)
D. G. Eisenhut letter to SEP Plant Licensees, dated January 14, 1981.
(2)
W. G. Counsil letter to D. G. Eisenhut, dated February 27, 1981.
Gentlemen:
Millstone Nuclear Power Station, Unit No. 1 SEP Topic 11-3.C, safety Related Water Supply (Ultimate Heat Sink)
As part of the redir' of the Systematic Evaluation Program, Reference (1),
Northeast Nuclear Ei wmpany (NNECO) committed to develop Safety Assessment Reports (SAR's) for certain SEP topics which would be submitted for Staff review. NNECO detailed this commitment and provided a schedule for submittal of SAR's in Reference (2).
In accordance with this commitment, NNECO hereby provides the Safety Assessment Report for SEP Topic 11-3.C, Safety Related Water Supply (Ultimate Heat Sink), which is included as Attachment 1.
We trust the Staff vill appropriately use this information to develop a Safety Evaluation Report for this SEP topic.
Very truly yours, NORTHEAST NUCLEAR ZNERGY COMPANY
$W W. di Counsil Senior Vice President f
5103050 R69
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Docket No. 50-2h5 Safety Assessment Report SEP Topic 11-3.C, Safety Related Water Supply (' itimate Heat Sink)
April,1981
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i Millstone Nuclear Power Station. Unit No.1 SEP Safety Asnessment Report Topic 11-3.C - Safety Related Water Supply (Ultimate Heat Sink) 1.0 Introduction The objective of this assessment is to review the adequacy of on-site water sources with respect to providing a safety related water supply during normal and emergency shutdown and for maintenance of a safe shutdown condition.
2.0 Criteria Regulatory Guide 1.27 (Revision 2) requires that:
1.
The ultimate heat sink should te capable of providing sufficient coolin8 for at least 30 days (a) to permit sbnultaneous safe shutdown and cooldown of all nuclear reactor units that it serves and to maintain them in a safe shutdown condition, and (b) in the event of an accident in one unit, to limit the effects of that accident safely, to permit simultaneous and safe shutdown of the remaining units, and to maintain them in a safe shutdown condition.
Procedures for ensuring a continued capability after 30 days should be available.
2.
The ultimate heat sink complex, whether composed of single or multiple water sources, should be capable of withstanding, without loss of the sink safety functions specified in regulatory position 1 the following events:
The most severe natural phenomena expected at the site, with a.
appropriate ambient conditions, Dut with no two or more such phenomena occurring simultaneously, b.
The site-related evonts (e.g., transportation accident, river diversion) that historically have occurred or that may occur during the plant lifetime, c.
Reasonably probable combinations of less severe natural phenomena and/or site-related events, d.
A single failure of manmade structural features.
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- 3.0 Discussion The ultimate heat sink for Millstone Unit 1 is the Long Island Sound.
Sensible heat iemoved from the Unit's systems during normal, shutdown, and accident conditions is discharged through the quarry and into Long Island Sound. Both the service water and circulating water systems have as their source of water Niantic Bay, which is fed from Long Island Sound.
The expected extreme icw water level at the site was developed and included as a part of the Millstone Unit 3 PSAR. NNECO has recently confirmed that the most conservatively calculated depression as developed for Millstone Unit 3 would not exceed the operable depth of the safety-related service water pumps located in the intake structure.
The intake structure has flood walls and gates to elevation 19 MSL in accordance with the original plant design for flood protection.
Subsequently, the flooding potential water level was increased to 1/.17 MSL in accordance with the revised probable maximum hurricane (PMH). A review of the impact of the increase of this level is detailed under Section 2.4.4 of the Millstone Unit 1 FSAR. The increase is not considered to pose a serious threat to operation of the emergency service water pumps. The flooding potential and protection requirements will be reviewed under SEP Topic 11-3.B.
The intake structure was designed to the plant seismic design criteria.
The design is such that all systems required for a safe shutdown will operate during an earthquake having a horizontal ground motion (zero period acceleration) of 0.17 g.
This design will "oe reviewed under SEP Topic 111-6.
Natural events that may reduce or limit the available cooling water supply have been addressed as follows: Due to the type, size, and location of the water supply, drought, effects of existing and proposed water control structures, use limitation, and supply availability are not considered applicable. Low water resulting from icing does not pose a threat since ocean temperatures prohibit significant icing.
Low water resulting from surges and the intake structure and pump design basis have been addressed above. In addition, the ability to dissipate the total essential station heat load, the effect of en-vironmental conditions on the capability of the UHS to furnish the required quantities of cooling water for extended times after shutdown, e.nd the sharing of cooling water with the other units also do not require further consideration due to the type, size, and location of the water supply. The effect of earthquakes, tornadoes, missiles, floods, and hurricane winds on the availability of the source water will be addressed under various associated SEP topics as dnscribed below. These reviews will address the intake structure and cooling systems. The above-m entioned effects on the Long Island Sound are
, _ ~.
s 3-not considered to pose a serious threat on the availability of the source water.
Associated SEP Topics o 11-3.B Flooding Potential and Protection Requirements o 111-1 Classifice. tion of Structures, Components, and Systems o 111-3 Wind and Tornado Loadings o 111-3.A Effects of High Water Level on Structures o 111-3.C Inservice Inspection of Water control Structures o Ill-4.A Tornado Missiles o 111 4.D Site Proximity Missiles o 111-6 Seismic Design Considerations o 111-7.B Design Codes, Criteria, and Ioad Combinations o V1-7.D Long-Term Cooling Passive Failures; i.e., Flooding of Bedundant Components o Vll-3 Systems Required for Safe Shutdown o V11 4 Effects of Failure in Non-Safety Related Systems _ on Selected Engineered Safety Features o V111-2 On-Site Energency Power Systems o 1X-3 Station Service and cooling Water Systems o XV-24 Loss of All AC Power o XV1 Technical Specifications h.0 Conclusions Pending resolution of the above topic reviews and based on this evaluation, NNECO concludes that an appropriate supply of cooling water during normal and emergency shutdown procedures will be assured.
1 S.O Reference 2 (1) Regulatory Guide 1.27 (Revision 2) Ultimate Heat Sink (2) Standard Review Plan Fection 2.4.11 Low Water C=..tsideratiens 9.2.5 Ultimate Heat Sink (3)
D. M. Crutchfield letter to L. D. White, dated December 12, 1980.
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