ML20245A573

Application for Amend to License DPR-61,supporting Coastdown Operation of Facility at End of Cycle 15,current Cycle

ML20245A573
Person / Time
Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	04/14/1989
From:	Mroczka E, Sears C CONNECTICUT YANKEE ATOMIC POWER CO., NORTHEAST UTILITIES
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20245A575	List: B13208, Proposed Tech Specs Supporting Operation of Cycle 15 ML20245A573
References
B13208, NUDOCS 8904250278
Download: ML20245A573 (6)

Text

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. NORTIMA5T UTILITIES o.nemi Ome.. . seiden street. Boriin Conn cticut artU 9

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. co (203) 665-5000 April 14, 1989 Docket No. 50-213 B13208 Re: 10CFR50.90 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, DC 20555 Gentlemen:

Haddam Neck Plant Cycle 15 Coastdown Proposed Chanaes to Technical Specifications Pursuant to 10CFR50.90, Connecticut Yankee Atomic Power Company (CYAPC0) hereby proposes to amend Operating License DPR-61 by incorporating the changes identified in Attachment 1 into the te,chnical specifications for the Haddam Neck Plant. These proposed changes are being submitted to support coastdown operation of the Haddam Neck Plant at the end of Cycle 15, the current cycle.

Backaround In a letter dated June 1, 1987,(I) CYAPC0 proposed to amend Operating License DPR-61 by incorporating certain changes into the technical specifications for ,

the Haddam Neck Plant. Specifically, the proposed changes supported operation  !

of the Haddam Neck Plant for Cycle 15. Included with that letter was a copy of the " Technical Report Supporting Cycle 15 Operation," prepared by Northeast Utilities Service Cpppany (NUSCO) on behalf of CYAPCO. In a letter dated November 12, 1987, W the NRC Staff issued Amendment No. 97, approving CYAPC0's license amendment request. Cycle 15 at the Haddam Neck Plant commenced on March 26, 1988. The Haddam Neck Plant will reach the.end of full l power core life as early as July 16, 1989. CYAPC0 desires to operate the Haddam Neck Plant in a coastdown mode for approximately 40 days past the end of Cycle 15 full power core life. The reason for this is the need for baseload nuclear generating capacity to meet the summer peak load in New England. It would be expedient to operate the Haddam Neck Plant through July and August when summer electricity supplies are marginal throughout this region.

(1) E. J. Mroczka letter to the U.S. Nuclear Regulatory Commission, " Cycle 15 Reload, Technical Specification Change Requests and Reload Report," dated June 1, 1987.

(2) F. M. Akstulewicz letter to E. J. Mroczka, " Technical Specifications for Cycle 15 Operation (TAC No. 65479)," dated November 12, 1987.

8904250278 890414 T /

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u U.S. Nucl. ear Regulatory Commission B13208/Page 2 Aprtl 14,1989 Accordingly, CYAPC0 is submitting the attached proposed technical specification changes to facilitate coastdown operation for this period at the end of Cycle 15. In addition, iacluded as Attachment 2 to this letter is the

" Technical Report Supporting tycle 15 Operations -

Coastdown Addendum,"

prepared by NUSCO for CYAPCO.

Description of Proposed Chanaes The proposed technical specification changes are submitted to support the operation of the Haddam Neck Plant in the coastdown mode at the end of Cycle 15. The Cycle 15 coastdown is defined as commencing when the reactor is at full power, all control rods are fully withdrawn, the primary system boron concentration is essentially zero parts-per million (ppm), and normal operating temperature can no longer be maintained. No three loop operation will be permitted during the coastdown.

Specifically, the proposed changes (by page) are as follows:

o Paae 1-5c. Section 1.0. Definitions l A definition of END-0F-CORE LIFE (1.40) has been added to describe the core ceaditions at the start of coastdown; o Paae 3-30. Section 3.17.1 - Axial Offset The limiting condition for operation and the surveillance requirements (a.) were changed to include a reference to Figure J 3.17.lc.

o Fiaure 3.17-Ic. Power level vs. Axial Offset This new figure provides the axial offset limits as a function of reactor power level during the Cycle 15 coastdown.

o Paae 3-31a. Section 3.17.2 - Linear Heat Generation Rate The limiting condition for operation has been changed to include a l reduced linear heat generation rate (LHGR) limit for the Cycle 15 J coastdown period. The limit has been reduced due to large break LOCA sensitivities. Plant operation at 100% power with a reduced reactor vessel inlet temperature during coastdown yields a higher peak clad temperature (PCT) for a postulated large break LOCA during this time. The reduction in the LHGR from 14.6 kw/ft to 13.5 kw/ft for coastdown conditions ensures that the PCT remains below the l 23000F limit for a postulated large break LOCA. Based on analysis  !

assumptions, for coastdown between 100 percent and 90 percent of l full power, the reactor vessel inlet temperature must remain above 1 5100F. Below 90 percent power, there is no limit on vessel inlet .

temperature. I

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U.S. Nuclear Regulatory Commission B13208/Page 3 April 14, 1989 I

Turbine Stoo Valve / Control Valve Testina for the 40 days that the Haddam Neck Plant is in the coastdown mode at the end of Cycle 15 (and for the 15 days pricr to reaching coastdown), CYAPC0 will not be performing the monthly turbine stop valve and control valve testing.

In order to perform surveillance testing on the turbine stop and control valves, reactor power must be reduced by a combination of control rod insertion and the addition of boron to the primary coolant. Due to the minimum rod height limitations in the technical specifications which ensure minimum shutdown margin, reducing power through the use of the control rods alone is not feasible. Therefore, power must be reduced by the addition of boron to the primary coolant.

The addition of boron, though certainly possible, poses additional problems.

After power is reduced and the surveillance completed, the boron would then need to be removed from the primary system through dilution and ion exchange processes. These activities result in increased radiation exposure and also generate a substantial quantity of radioactive waste. Thus, power reductions while operating at or near the coastdown mode are not desirable.

Routine surveillance on the turbine stop and control valves was last performed on March 20, 1989. Based on an expected shutdown date of late August /early September 1989, we would expect to perform surveillance testing on these valves three more times (during April, May, and June). A review of the surveillance test results for Cycle 15 revealed no problems with getting the j stop valves and control valves to close. Based on the above considerations,  !

namely the increased man-rem exposure and the generation of additional radioactive waste, CYAPC0 has determined that an additional stroke test of the turbine stop and control valves just prior to and during coastdown operation j is not warranted. Following the refueling outage, we will resume our practice i of performing surveillance on these valves every 30 days. {

i Significant Hazards Consideration In accordance with 10CFR50.92, CYAPC0 has reviewed the attached proposed changes and has concluded that they do not involve a significant hazards consideration. The basis for this conclusion is that the three criteria of 10CFR50.92(c) are not compromised. The proposed changes do not involve a significant hazards consideration because the changes would not:

1. Involve a significant increase in the probability or consequences of an accident oreviously evaluated.

Operation during coastdown is beyond the scope of the current design basis LOCA analysis for the Haddam Neck Plant. The current design basis assumes operation consistent with the Tave program. Coastdown operation immediately following end of core life maintains 100% thermal power by reducing Tave, while fully opening the turbine control valves. Past LOCA

U.S. Nuclear Regulatory Commission l B13208/Page 4 ,

j April 14, 1989 '

1 analysis sensitivities have shown that a reduction in the core inlet temperature, while maintaining full power, yields an increase in the projected peak cladding temperature (PCT) for the large break LOCA. This I l

increase in PCT is due to the reduction in reverse core flow during i

blowdown after the coastdown of the reactor coolant pumps. The reduced flow yields higher temperatures at the end of blowdown, which yields a higher PCT after the adiabatic heatup and beginning of core recovery.

These sensitivities have also shown that between 100 and 90% power, the sensitivity to the core inlet temperature becomes insignificant relative to the drop in power.

In order to bound operation during coastdown, the current limiting case (double ended, cold leg guillotine, Cn = 1.0) was re-analyzed at full power, but with a bounding coastdown c&re inlet temperature at 90% power

, (Tinlet - 5100F). This re-analysis shows that the limiting LHGR must be i reduced from the normal end of cycle value of 14.6 kw/ft to 13.5 kw/ft to '

maintain the PCT less than the Interim Acceptance Criteria limit of 23000F.

The axial offset (AO) limits were developed for the new LHGR limit during coastdown. The new A0 limits are slightly more restrictive on the negative side.

The proposed changes ensure that there is no increase or change in the probability of occurrence of any design basis accidents.

2. Create the possibility of a new or different kind of accident from any oreviousiv evaluated.

The proposed changes to the technical specifications ensure that the plant response to an accident during coastdown operation is essentially within the design basis of the plant.

The large break LOCA response during coastdown has been changed, but the PCT as a function of time after break retains the key characteristics associated with blowdown, refill and reflood. The reduction in the LHGR ensures that the PCT remains less than 23000F for a postulated design basis event during coastdown conditions.

There are no new failure modes associated with the proposed technical specification changes. Therefore, the changes do not present the possibility for a new, unanalyzed accident.

3. Involve a significant reduction in a marain of safety.

l The proposed changes to the technical specifications ensure that the margins of safety have not been reduced significantly. The reduction in I the allowable LHGR from 14.6 to 13.5 kw/ft during coastdown operation l

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4 4 U.S. Nuclear Regulatory Commission  :

B13208/Page 5 '

April 14, 1989 after the end of core life restores the PCT to less than 23000F. The new A0 limits provide alarm points to assure that operation aheve an LHGR of 13.5 kw/ft is prohibited. Since the PCT remains less than 23000F, i there is no impact on the protective boundaries.

Moreover, . the Commission has provided guidance concerning the application standards in 10CFR50.92 by providing certain examples (March 6, 1986, 51FR7751) of amendments that are considered not likely to involve a significant hazards consideration. Although the proposed change herein is not enveloped by a specific example, the proposed change would not involve a significant increase in the probability or consequences of an accident previously analyzed. As stated earlier, the proposed changes will ensure that there is no significant increase in the consequences of an accident that occurs during coastdown operation. In addition, the changes do not create a new unanalyzed event nor do they increase the probability of an accident to the point where it should be part of the design basis. Finally, the proposed changes will provide assurance that the PCT limit will be maintained.

Based upon the information contained in this submittal and the environmental l assessment for the Haddam Neck Plant, there are no significant radiological or nonradiological impacts associated with the proposed action, and the proposed license amendment will not have a significant effect on the quality of the human environment.

The Haddam Neck Plant Nuclear Review Board has reviewed and approved the attached proposed revision and concurs with the above determinations.

In accordance with 10CFR50.91(b), CYAPC0 is providing the State of Connecticut with a copy of this amendment.

We trust you find this information satisfactory for issuance of the requested amendment. CYAPC0 requests review and issuance of this proposed license amendment by July 15, 1989 to support coastdown operation to begin shortly thereafter.

Very truly yours, CONNECTICUT YANKEE ATOMIC POWER COMPANY l h , d . b ne  %.

E. J. Mroczka Senior Vice President l C ONL By: C. F. Sears Vice President J

U.S.' Nuclear Regulatory Commission B13208/Page 6 April 14, 1989 cc: W. T. Russell, Region I Administrator A. B. Wang, NRC Project Manager, Haddam Neck Plant J. T. Shedlosky,-Senior Resident Inspector, Haddam Neck Plant Mr. Kevin McCarthy Director, Radiation Control Unit Department of Environmental Protection Hartford, CT 06116 STATE OF CONNECTICUT)

) ss. Berlin COUNTY OF HARTFORD )'

Then personally appeared before me, C. F. Sears, who being duly sworn, did state that he is Vice President of Connecticut Yankee Atomic Power Company, a Licensee herein, that he is authorized to execute and file the foregoing information in -the name arid on behalf of the Licensees herein, and that the statements contained in said information are true and correct to the best of his knowledge and belief.

$w  % . llt0Al Notiry Public q

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