ML19305D956
| ML19305D956 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck, Millstone File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 04/11/1980 |
| From: | Counsil W CONNECTICUT YANKEE ATOMIC POWER CO., NORTHEAST NUCLEAR ENERGY CO. |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| References | |
| RTR-NUREG-0578, RTR-NUREG-578, TASK-10, TASK-RR TAC-42410, TAC-44705, TAC-44746, NUDOCS 8004170012 | |
| Download: ML19305D956 (4) | |
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NORTHEAST trrII.rrlES
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PO Box 270
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1.". ' ~ l April 11, 1980 Docket Nor,. 50-213 50-3,3,6, Darrell G. Eisenhut, Actirs Director Division of Operating Reactors Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Commission Washington, D. C.
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References:
(1)
W. G. Counsil letter to J. Hendrie dated November 30, 1979 (Docket Nos. 50-213, 50-336).
(2)
H. R. Denton letter to All Operating Nuclear Power Plants dated October 30, 1979 (3)
W. G. Counsil letter to H. R. Denton dated December 6, 1979 (Docket Nos. 50-213, 50-336).
(4)
W. G. Counsil letter to H. R. Denton dated December 17, 1979 (Docket No. 50-336).
(5)
R. Reid letter to W. G. Counsil dated December 21, 1979 (Docket Nos. 50-213, 50-336).
(6)
H. R. Denton letter to W. G. Counsil dated December 27, 1979 (Docket Hos. 50-213, 50-336).
(7)
W. G. Council letter to R. Reid dated January 25, 1980 (Docket No. 50-336).
(8)
W. G. Counsil letter to D. L. Ziemann dated January 30, 1980 (Docket No. 50-213).
(9)
D. G. Eisenhut letter to W. G. Counsil dated March 27, 1980 (Docket Nos. 50-213, 50-336).
(10)
H. R. Denton letter to W. G. Council dated December 27, 1979 (Docket Nos. 50-245, 50-336).
Gentlemen:
Haddam Neck Plant Millstone Nuclear Power Station, Unit No. 2 Automatic Initiation of Auxiliary Feedwater In heference (1), Connecticut Yankee Atomic Power Company (CYAPCO) and Northeast Nuclear Energy Company (NNECO) provided a comprehensive description of the evolution of the NRC Staff requirement to automate initiation of the auxiliary feedwater system, and the status of the implementation effort at the Haddam Neck Plant r.nd Millstone Unit No. 2.
tieference (1) also forwarded CYAPCO's and NNECO's determination pursuant to the requirements of 10CFR50.59 Subsequent telephone discuasions with the Staff resulted in a Staff request for specific design details, and demonstration of compliance with each of the clarification points delineated in Reference (2). This request was f) 800417g OI2
fulfilled by Referet.ce (3), in which CYAPC0 and NNECO provided a summary of the proposed schemes, as well as demonstration of compliance with each of the clarification items of Reference (2) on an individual basis.
In the case of Millstone Unit No. 2, Reference (3) was supplemented by the docketing of Reference (h ), which transmitted design drawings which further illustrated how compliar:;e with the clarification items of Reference (2) was achieved.
Via Reference (5), CYAPC0 and NNECO were advised of a revision to the Staff directive of Reference (2), in thst implementation of automatically initiated auxiliary feedwater was prohibited until the NRC Staff completes its review and issues an approval.
In Reference (6), the Staff accepted CYAPCO's and NNECO's determination pursuant to 10CTR50.59, and reiterated the need for an analysis of an automatically initiated system.
The Staff further advised that Reference (6) should not be construed as a detailed reply to each of the concerns expreased in Reference (1). We continue to look forward to receipt of the detailed reply.
The Staff requests of Reference (5) were fulfilled by References (T) and (8) for the Haddam Neck Plant and Millstone Unit No. 2, respectively. These latter two references, which have been the subject of recent telephone discussions, addressed the consequences of automatically initiated auxiliary feedwater during a postulated Main Steam Line Break (MSLB).
Both return to power and containment pressure considerations were addressed. With respect to Reference (8), the following clarification is noted. On Page 2 of the transmittal letter, the conservatisms inherent in the analysis were listed.
Item (6) stated that the highest worth rod control cluster assembly was assumed to stick in the fully withdrawn position.
It should be noted that for the zero power case, this assembly was conservatively assumed to be stuck at the 50% withdrawn position, in accordance with Technical Specification limits.
The statement is accurate as written with respect to the full power case.
In Reference (9), the Staff provided additional guidance regarding implementa-tion of Item 2.1.Ta of NUREG-0578, including a revised schedule. With respect to the requests of Reference (9), CYAPC0 and NNECO provide the following information.
Reference (9) refers to a January 2,1980 letter regarding Millstone Unit No. 2.
NNECO is not aware of any such letter addressing Category A lessons-learned requirements on that date.
It is NNECO's understanding that it was the Staff's intent to refer to Reference (10).
Another statement in Reference (9) is judged to be subject to possible mis-interpretation and is, therefore, clarified as follows. Reference (9) states that CYAPC0 and NNECO are required to implement the 2.1.Ta "short-term" requirement without prior NRC approval of the design. This statement appears to conflict with the directive of Reference (5) which requires Staff review and approval prior to implementation. The latter interpretation is consistent with the provisions of 10CFR$0.59 in light of the detennination forwarded in Reference (1), that bnplementation of automatic initiation of auxiliary feedwater constitutes an unreviewed safety question. This detennination
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remains unchanged. It is acknowledged that Reference (9) indicates that it is the Staff's intent to provide a safety evaluation prior to June 1, 1980.
In the interest of ensuring clarity of CYAPCO's and NNECO's position, implementation of the 2.1.Ta requirements will not occur until the unrevleved safety question issue is favorably dispositioned by the Staff.
With respect to the control-grade systems at the Haddam Neck Plant and Millstone Unit No. 2, References (3) and (4) fully described the proposed installation.
This information remains accurate except for a change in the initiation logic at the Haddam Neck Plant which was conceived since the docketing of Reference (3).
Initiation of auxiliary feedwater will occur when any two out of four level instruments indicate that a low-level condition exists. One vide-range level instrument on each steam generator will be utilized for this purpose.
This revised initiation logic remains in complianer with the single failure criterion as required by Reference (2).
heference (9) requests a commitment to install a control system by June 1, 1980. Regarding the Haddam Neck Plant, the 1980 refueling outage is scheduled to begin in May, 1980. Therefore, assuming the Staff continues to disagree with CYAPC0 regarding the necessity and appropriateness of this system, CYAPCO will have a control grade scheme operational prior to resuming operation following the refueling outage.
Regarding Millstone Unit No. 2, the 1980 refueling outage is scheduled to begin in July,1980. The undesirability of installing the system during plant operatior, has resulted in NNECO's schedule for installation to take place during the 1980 refueling outage. The delay is justified in that only approximately six weeks of plant operation beyond the Staff's requested date of June 1,1980 are scheduled. Other measures which have been taken in response to TMI-related investigations provide thorough assurance that the system will be manually initiated if needed.
As noted above, installation during plant operation is feasible but not desirable.
To implement the design at Millstone Unit No. 2, modifications to the control circuits of the terry-turbine governor, the terry-turbine steam admission valve, the electric auxiliary feedwater pumps, and associated control valves are necessary. Removal of this equipment from service to make the modifications will require the use of action statements in Technical Specifications.
Additionally, a variety of delicate operations will have to be conducted on the main contral board.
New holes would have to be drilled for indicating lights and control switches and interconnections would have to be provided to the ESAS actuation cabinets. A fire barrier would also have to be constructed in the main control board.
A considerable amount of work involving bistables and relays is also required.
Equipment and components will have to be seismically mounted, and new connections for AC power to energized circuits would be necessary. From the above synopsis, it is clear that for limited periods of time, the plant would have an increased susceptability to spurious trips. The use of action statements would be necessary.
Considering the duration of the delay, approximately six weeks, and the fact
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that after completion, the estimation of the degree to which plant safety is enhanced remains subjective, implementation of the 2.17a requirement during the 1980 refueling outage is the most appropriate course of action. To ensure i
that NNECO's efforts are not expended unnecessarily, your prompt concurrence, in either verbal or written form, would be most appreciated.
Reference (9) also requested CYAPCO and NNECO to supply details regarding the I
safety-grade installation. Plans are not finalized as of this writing, but the safety-grade installations are anticipated to be conceptually identical
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to the control-grade schemes previously provided to the Staff. However, it is planned that the initiating signals and circuits will be environmentally qualified to perform their design function, either by verification'of the t
adequacy of existing components or by replacement. A target date of January 1, i
1981 has been established; the feasibility of meeting this target has yet to be ascertained. The final safety-grade designs, and an assessment of the l
feasibility of complying with the requested date, will be docketed in future correspondence as soon as the information is available.
i References (7) and (8) indicated that the design review of the control-grade e
scheme and the review of proposed Technical Specifications were in progress.
Recent refinements to the original proposals have prohibited their completion as of this writing. Therefore, all the steps necessary to reach a definitive conclusion regarding the acceptability of automatic initiation of auxiliary l
feedwater at the Haddam Neck Plant and Millstone Unit No. 2 have not been completed. Furthermore, the necessity of these modifications remains doubtful for reasons documented in Reference (1).
It is currently planned that the-above-mentioned future submittal vill address, for both facilities:
4 (1) The final safety-grade designs; (2) The proposed revisions to Technical Specifications; and (3) The acceptability of the installations from a safety perspective.
In the interim, our request for withdrawal of this requirement for the Haddam Neck Plant and Millstone Unit No. 2 is reiterated.
In the absence of the-above, concurrence in the deferral of the control-grade installation at Millstone Unit No. 2 until the 1980 refueling outage would be most appreciated.
We trust you find the above information responsive to your requests.
Very truly yours, CONNECTICUT YANKEE ATOMIC POWER COMPANY' NORTHEAST NUCLEAR ENERGY COMPANY N
W. G. Counsil.
Vice-President l
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