ML20052D562
| ML20052D562 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 04/22/1982 |
| From: | Miraglia F Office of Nuclear Reactor Regulation |
| To: | Tallman W PUBLIC SERVICE CO. OF NEW HAMPSHIRE |
| References | |
| NUDOCS 8205060582 | |
| Download: ML20052D562 (9) | |
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Document Control: 50-443/444 NRC PDR APR 2 21982 L PDR NSIC Docket Nos: 50-443 TERA and 50-444 TIC LB#3 File JLee p
Mr. William C. Tallman DWheeler g
Chairman and Chief Executive Officer RLessy, OEL c3 Public Service Company of New Hampshire I&E g.O Post Office Box 330 ACRS (16) 1
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Dear Mr. Tallman:
Subject:
Seabrook Auxiliary Feedwater System The NRC Instrumentation and Control Systems Branch (ICSB) met with y representatives March 23-25, 1982 to discuss the plant design as it pertains to FSAR Chapter 7.0.
During discussions on the Seabrook AFWS instrumentation and control, the ICSB identified a number of potential concerns which are based on staff design criteria used on recent plant reviews. A list of the various ICSB concerns and requests for additional information is enclosed.
After your representatives have reviewed the enclosure, they should contact the Seabrook Project Manager (Mr. Louis Wheeler, 301/492-7792) to arrange a meeting to resolve their concerns.
The NRC proposef that the meeting A
be in Bethesda to provide imediate access to review branches other than ICSB whose participation may be desired as the meeting progresses (Auxiliary Systems Branch, Reactor Systems Branch for example).
During such a meeting, your representatives should be prepared to discuss the degree of compliance of the Seabrook design with each item in the enclosure.
Sincerely, Original signed by Frank J. Miraglia Frank J. Miraglia, Chlief Licensing Branch No. 3 -
Division of Licensing
Enclosure:
As stated cc w/ enclosure:
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OFFICIAL RECOFiD COPY
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SEABROOK William C. Tallman Chairman and Chief Executive Of ficer Public Service Company of New Hampshire P. O. Box 330 Manchester, New Hampsnire 03105 John A. Ritscher, Esq.
E. Tupper Kinder Esq.
Ropes and Gray Assistant Attorney General 225 Franklin Street Office of Attorney General Boston, Massachusetts 02110 208 State House Annex Concord, New Hampshire 03301 Mr. Bruce B. Beckley, Project Manager Public Service Company of New Hampshire Tne Honorable Arnold Wight P. O. Box 330 New Hampshire House of Representatives Manchester, New Hampshire 03105 Science, Technology and Energy Committee State House G. Sanborn Concord. New Hampshire 03301 U. S. NRC - Region 1 631 Park Avenue Resident inspector King of Prussia, Pennsylvania 19406 Seabrook Nuclear Power Station c/o U. S. Nuclear Regulatory Commission Ms. Elizabeth H. Weinhold P. O. Box 700 3 Godfrey Avenue Seabrook, New Hampshire 03874 Hampton, New Hampshire 03842 Mr. John DeVincentis, Project Manager Robert A. Backus Esq.
Yankee Atomic Electric Company O'Neill, Backus and Spielman 1671 Worcester Road 116 Lowell Street Farmingham, Massachusetts 01701 Manchester, New Hampshire 03105 Mr. A. M. Ebner, Project Manager Norman Ross, Esq.
United Engineers and Constructors 30 Francis Street 30 South 17th Street Brookline, Massachusetts 02146 Post Office Box 8223 Philadelphia, Pennsylvania 19101 Karin P. Sheldon, Esq.
Sheldon, Harmon & Weiss Mr. W. Wrignt, Project Manager 1725 I Street, N. W.
Westinghouse Electric Corporation Washington, D. C.
20006 Post Office Box 355 Pittsburg, Pennsylvania 15230 Laurie Burt Esq.
Office of the Assistant Attorney General Thomas Dignan, Esq.
Environmental Protection Division Ropes and Gray One Ashburton Place 225 Franklin Street Boston, Massachusetts 02108 Boston, Massachusetts 02110 D. Pierre G. Cameron, Jr., Esq.
General Counsel Public Service Company of New Hampshire P. O. Box 330 Manchester, New Hampshire 03105 m
ENCLOSURE w
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c BACKGROUND:
Recent plant reviews have included a number of considerations which assure the use of the auxiliary feedwater system (AFWS) as an effective post trip decay heat removal system.
These considerations include:
1.
Automatic Initiation, 2.
The capability to control flow to establish and maintain steam generator level, 3.
The capability to control steam generator pressurc, 2
4.
The capability to isolate faulted steam generators due to feedwater/steamline breaks, and 5.
The capability for post trip control from remote shutdown panels.
POTENTIAL CONCERNS:
During ICSB's review and through discussions with the applicant, a number of potential concerns have been identified pertaining to the Seabrook AFWS design.
The design concerns for the Seabrook AFWS are:
i 1.
The use of a non-safety-grade air system, 2.
The use of a single air-operated valve to automatically terminate auxiliary feedwater flow to a faulted steam generator, 3.
The use of a single air-operated valve (full open or full close-no i
modulation) for flow control to each steam generator to maintain steam generatar level, 4.
The use of air-operated atmospheric steam dump valves with non-safety-grade control circuitry to control steam generator pressure, E
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5.
The use of local handwheel operated valves which could defeat all or partial operation of the AFWS, 6.
The capability to control auxiliary feedwater flow from outside the control room via the rerote shutdown panel with a loss of one train of power, 7.
The continuous use of block valves or the continuous stopping and start-t ing of AFW pumps as required to control flow, and 8.
The operation of locally operated (outside the control room) block valves to isolate the faulted steam generator upon a single failure.
REQUESTS FOR ADDITIONAL INFORMATION:
As a basis for further discussion (s) and to help the staff to better understand the Seabrook AFWS, we propose that the applicant address the following design criteria which have been used by the ICSB in reviewing recent AFWS designs.
The applicant should provide discussion and additional information on each of the design criteria which follow.
I i
a)
The capability for decay heat removal using the auxiliary feedwater system I
I should not be dependent upon the use of non-safety grade equipment nor i
local operation of equipment following any design basis event for which the system function is required.
If required to demonstrate that the system can fulfill its safety function assuming a single failure, limited operator action outside the control room nay be found acceptable if suitably justified and not required for at least 30. minutes following any design basis event.
L
J b)
Since a non-safety grade instrument air system is used during system Ii operation, it should be backed up by suitable air accumulators or an alternate air source which satisfies safety grade and redundancy require-ments for the AFW system.
Where air accumulators are used they should have the capacity to maintain the equipment in service to permit opbration at hot standby for at least four hours and the time to cool-down to the conditions permitting operation of the RHR system such that control of decay heat removal may be performed from the control room without local operation of valves.
If an a ternate air source is used, it should be automatically placed in service when required or be capable i
of manual operation from the control room.
Appropriate technical specifications should be applied to the safety grade portion of instrument air or back up systems and the design should include provisions for sur-veillance testing including features used for isolation from the non-safety grade portion of the system.
Also, the safety-grade and non-safety grade portions of the air systen should be specifically identified, and isolation should be provided between safety-grade and non-safety grade positions of the system.
c)
The control of steam generator level (flow control) from the control room should satisfy single failure requirements consistent with the redundancy requirements of the AFW system and not be dependent on the use of non-safety grade equipnent.
If operator action to control AFW flow is required prior to 10 7ninutes af ter system initiation, automatic control of steam generator level should be provided.
If the use of block valves or the stopping and starting of ATW pumps is required to satisfy the single failure requirement of this position, an analysis should be provided to confirm that this operating mode is within the limitations of the equipment and their power sources as well as being a suitable means to control steam generator level to effect shutdown for all design bases events.
t i
_4 d) The control of steam generator pressure from the control room should satisfy single failure requirements consistent with the redundancy requirements of the AFW system and not be dependent on the use of non-safety grade equipnent.
e)
The capability to terminate auxiliary feedwater flow to a faulted steam generator from the control room should satisfy single failure requirements and not be dependent on the use of non-safety grade equipment.
If the design does not require termination of AFW flow to a faulted steam generator within 30 minutes or longer, limited operator action outside the control room may be found acceptable if suitably justified.
Any single failure which could preclude the capability to terminate AFW flow from the control room should not also preclude the availabilityof suitable information to identify the faulted steam generator.
If termination of AFW flow to a faulted steam generator is required prior to 10 minuter for any-design basis event, an automatic system should be provided in accordance with pro-tection system requirements (_IEEE Std. 279).
f) Operating control features of the AFW control system should not have the capability to block automatic initiation of the AFW system.
Those valves, including manual control valves, which would be closed or opened during testing at power or during plant startup should be provided command signals by the AFW automatic initiation system to assure that they are in the correct position or such valves should provide input signals to the bypassed and inoperable status indication system for the AFW system when in the incorrect position.
= -
The applicant should identify all valves which fall into this category and describe each valve operation based on the above design consideration.
g) 1.
Valves which could be placed in a position which could block initiation of any portion of the AFW system should have control room position indication.
2.
A single valve, or multiple valves in series which could be placed in a position which could block initiation of all nonnal AFW system flow should have redundant, safety grade control room position indication.
All valves that fall into the above categories should provide input signals to the bypassed and inoperable status indication system for the AFW system.
The applicant should identify all valves which fall into these cctegories and describe each valve function based on the above design consideration.
h)
If the circuits for the automatic initiation of the AFW system include inhibits to block the initiation of the system, such inhibits shall be automatically removed for operating conditions for which the safety function is required.
Anticipatory trips, if not automatically rein-stated, should be identified by the bypassed and inoperable status indication system when the trips are required.
c, o
The applicant should identify any inhibits which exist and discuss the Seabrook design based on the above concern.
1)
It appears to be common practice in Westinghouse plant designs to provide automatic initiation of auxiliary feedwater systems on the tripping of main feedwater pumps (loss of main feedwater flow). This design feature is not included as part of the Seabrook design.
Please pro-vide a discussion on this issue and justify why this commonly used AFWS initiation function is not required for Seabrook.
j)
If the protective system can take action which precludes operating capabilities provided at renote shutdown panels and this action can be initiated due to the consequences of post trip conditions, the capability should be provided at the remote shutdown panel to indicate the status of the protection system and to permit the reset of the protection system such that safe shutdown conditions can be maintained.
The applicant is requested to discuss the Seabrook design as it relates to the above concern.
I k) The Seabrook design for auxiliary feedwater flow control from outside
)
the control room allows the control of only two of the four control valves from any one of the redundant remote shutdown panels (i.e.,
two valves are controlled from panel 108A and the remaining two are controlled from panel 108B).
Therefore, a single failure (loss of one train of power for example) on one of the remote shutdown panels 1
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- would leave the operator with flow control for only two steam generators.
furtherrore, loss of one train of power would result in continuous, un-controlled flow to the remaining two steam generators.
Please provide discussion on this phase of the design as it relates to item (c) above.
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