ML19340B047
| ML19340B047 | |
| Person / Time | |
|---|---|
| Site: | Dresden  |
| Issue date: | 07/10/1973 |
| From: | Skovholt D US ATOMIC ENERGY COMMISSION (AEC) |
| To: | Butterfield L COMMONWEALTH EDISON CO. |
| References | |
| NUDOCS 8010170757 | |
| Download: ML19340B047 (5) | |
Text
sistribution
,D_ct.ket File
, AEC PDR Branch Reading JUL 1o e,j RP Reading JRBuchanan, ORNL Tr.'Laughlin, DTIE DJSkovholt, L:0R nocket tio. 50-10 TJCarter, L:OR DLZic= ann, L:0RB #2 RDSilver, L:0RB #2 RMDiggs, L:0RB #2 Co:mnonwealth Edison Company R0 (3)
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Mr. L. D. Butterfield, Jr.
OGC Nuclear Licensing Administrator ACRS (16)
Post Office Box 767 Chicago, Illinois 60690 Gentlemen:
We have reviewed the conceptual design for a high pressure coolant injection (EPCI) systen proposed in your letter of May 16, 1973.
Eased on this review, we have concluded that the general approach to providing energency core cooling for Dresden Unit I as described in that proposal is acceptable. However, enclosed are com::ents and questions regarding your conceptual design that should be responded to within 60 days of this letter with one signed original and thirty-nine additional copies. We are of the opinion that the design and installation of the HPCI system should proceed on a high priority basis, that your detailed analysis and design should proceed concurrently with your preparation of a reply to our questions, and that your schedule need not be delayed by our questions.
Since your proposed 30-month schedule specified an operability date beyond July 1,1974, and appears somewhat long for a high priority project, we request that a more detailed schedule and justification for the schedule be submitted with the reply to our questions.
It is our understanding, based on a telephone call with Mr. Tramm, that a reply to our questions of June 6,1972, on the core spray will be submitted about August 1,1973.
Sincerely, Oriz;inal Sicned 17:
nontid J. Skovholt Donald J. Skovholt isssistant Director for Operating Fasctors Directorate of Licensing Enclosure and cc: See next page
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2-JUL 101973 Comonwealth Edison Company 1
Enclosure:
I Additional Information Request cc w/ enclosure:
John W. Rowe, Esquire Isha::, Lincoln L Beale Couarselors at Law One First National Plaza Chicago, Illinois 60670 i
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I ADDITIONAL INFORMATION REOUEST i
4 1.
As presently proposed, coolant injection could be prevented or
' reduced by pipe failures at several locations.
Discuss means to increase reliability by providing two independent systems from the water tank to the primary system.
Include in this discussion means such as one line injecting at a location that results in equal access between the existing feedwater connections to the steam drum and a second line injecting directly into the low pressure core spray no:=le.
Also discuss means which could provide redundancy in the lines penetrating containment.
2.
Discuss design and surveillance plans which would allow periodic cold water injection through the motor-operated valves into the reactor vessel. Discuss the need for any design modifications which might be necessary to handle transients caused by accidental or planned cold water injections into the primary coolant system.
3.
It is our opinion that the omission of redundant valving on the emergency condenser has not been adequately justified. Redundant valving would improve emergency condenser reliability and, the ref.o re, reliability for coping /with a large range of break j
sizes. Provide plans for installation of the redundant valving or proposed alternative means of providing the additional equivalent 4
reliability.
4.
Discuss plans to assure that pipe stresses resulting from cold water injection are acceptable at the connection of the upCI piping to the existing system and at the connection of the feedwater system to the steam drum.
5.
Submit preliminary technical specifications in sufficient detail to indicate that necessary limiting conditions of operation and surveillance requirements, including inservice inspection can be accommodated by your design.
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'fp July 10, 1973 Files (Docket No. 50-10)g Dennis L. Ziemann,3 '
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ief, Operating Reactors Branch "2,
L HIGl PRESSURE COOLANT INJECTION SYSTEM - CONCEPTUAL DESIGN FOR DRESDEN UJIT 1 (C0FNONWEALTH EDISON COMPANY)
Commonwealth Edison Company (CEC) has requested by letter and attached report dated Fby 16, 1973, our review and comments on the conceptual design for a High Pressure Coolant Injection (HPCI) system and a new emergency cooling water storage tank for Dresden 1.
According to CEC, the proposed HPCI system with a rated capacity of about 1000 gpm at 1250 psi in conjunction with the existing low pressure core spray system will provide continuity of cooling over the complete range of postulated break sizes for reactor operation at a power level of 700 MWt and 15.5 kW/f t peak linear power and limit peak fuel clad temperature to less than 2300*F. A new 200,000-gallon storage tank will be provided to supply cooling water to the existing low pressure core spray system and the proposed high pressure coolant injection system.
CEC states 'that two HPCI pucps, each driven by a 1000 hp diesel engine directly coupled through a speed reducer, will eliminate dependence on offsite power for emergency core cooling.
Each diesel engine will be
" supplied by a diesel oil day tank with enough fuel to last approximately -
3-1/3 hours. We have reviewed the proposed system design requirements for the new storage tank and the HPCI system and have concluded that they are adequate. We also have concluded, based on the information provided, that the proposed HPCI system and the new demineralized water storage tank for emergency core cooling will significantly improve the emergency core cooling capability by eliminating dependence en offsite electric power and the firemain system for small but more probable core cooling system breaks, i.e., less than about 5 inches equivalent pipe diameter.
On this basis, the plans for the proposed system modifications should move forward so that CEC can complete the detailed analysis according to the CEC schedule, by December 1973.
The detailed aumlysis, in addition to the items identified by CEC, should include:
1.
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Files July 10, l'/3 4
1.
an analysis of' thermal stresses during cold water addition at the thermal sleeve where the new HPCI piping connects to the existing feedwater system.
2.
a thermal analysis of the capability of existing feedwater connections to the steam drum to withstand cold unter transients l
accompanying HPCI.
3.
an evaluation of other coolant injection locations such as at a
location that results in equal access to the steam drum through the existing feedwater connections (refer to drawing MS-109 -
Preliminary Concept dated April 17, 1973).
4.
an evaluation of high pressure coolant injection reliability considering alternate injection at the low pressure core spray nozzle.
5.
justification for the omission of redundant valving on the emergency condenser, as previously resolved, to improve.
emergency core cooling reliability for the small break sizes and assist in core cooling and depressurization for small and intermediate size breaks.
6.
an analysis of accidental high pressure cold water injection.
7.
an analysis of any bases for not conducting periodic tests that inject cold water into the reactor vessel.
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James J. Shea Operating Reactors 3 ranch #2 Directorate of Licensing
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Richard D. Silver Operating Rcacters Branch #2 Directorate of Licensing cc:
Commonwealth Edison AEC PDR D. J. Skovholt, L:0R T. J. Carter, L:0R D. L. Ziemann, L:0RB #2 J. J. Shea,. L:0RB #2 R. D. Silver, L:0RB #2 R.
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