B12296, Forwards Reviews of Isap Topics 2.08, Loss of DC Power Study, Isap 2.14, Radiation Monitoring Sys Updrade, Isap 2.18, Nuclear Instrumentation Replacement & Isap 2.19, Pcb Oil-Filled Transformer, Per 850731 Request

Forwards Reviews of Isap Topics 2.08, Loss of DC Power Study, Isap 2.14, Radiation Monitoring Sys Updrade, Isap 2.18, Nuclear Instrumentation Replacement & Isap 2.19, Pcb Oil-Filled Transformer, Per 850731 Request

ML20213D631
Person / Time
Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	10/30/1986
From:	Opeka J, Sears C CONNECTICUT YANKEE ATOMIC POWER CO.
To:	Charemagne Grimes Office of Nuclear Reactor Regulation
References
B12296, NUDOCS 8611120164
Download: ML20213D631 (9)

Text

1 o o CONNECTICUT YANKEE ATOMIC POWER COMPANY B E R L I N. CONNECTICUT P.o Box 270 HARTFORD CONNECTICUT 06141-0270 TELEPHONE 8 co34ss-sooo Docket No. 50-213 B12296 Office of Nuclear Reactor Regulation Attn: Mr. Christopher I. Grimes, Director Integrated Safety Assessment Project Directorate Division of PWR Licensing - B U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Gentlemen:

Haddam Neck Plant Integrated Safety Assessment Program  !

In a letter dated July 31, 1985,(1) Connecticut Yankee Atomic Power Company (CYAPCO) was requested to provide the Staff with reviews of the planned CYAPCO plant improvement projects.

In response to this request, and in accordance with our understanding of the ISAP process, we are providing the Staff with reviews of the following projects:

1) ISAP Topic No. 2.08 " Loss of DC Power Study"

2) ISAP Topic No. 2.14 " Radiation Monitoring System Upgrade"

3) ISAP Topic No. 2.18 " Nuclear Instrumentation Replacement"

4) ISAP Topic No. 2.19 "PCB Oil-Filled Transformers" If you have any questions concerning the attached reviews, please contact us.

Very truly yours, CONNECTICUT YANKEE ATOMIC POWER COMPANY

. .O

3. F. Opeka '

Senior Vice President 8611120164 861030 DR ADOCK 0500 3 By: C. F. Sears Vice President (1) H. L. Thompson letter to 3. F. Opeka, " Integrated Safety Assessment Program," July 31,1985.

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o o CONNECTICUT YANKEE ATOMIC POWER COMPANY B E R L I N. CONN E C TICUT P.O. box 270 HARTFORD. CONNECTICUT 06141-0270

,, ,, October 30,1986 203-665-5000 Docket No. 50-213 B12296 Office of Nuclear Reactor Regulation Attn: Mr. Christopher I. Grimes, Director Integrated Safety Assessment Project Directorate Division of PWR Licensing - B U.S. Nuclear Regulatory Commission Washington, D.C. 20535 Gentlemen:

Haddam Neck Plant Integrated Safety Assessment Program In a letter dated July 31,1985,(I) Connecticut Yankee Atomic Power Company (CYAPCO) was requested to provide the Staff with reviews of the planned CYAPCO plant improvement projects.

In response to this request, and in accordance with our understanding of the ISAP process, we are providing the Staff with reviews of the following projects:

1) ISAP Topic No. 2.03 " Loss of DC Power Study"

2) ISAP Topic No. 2.14 " Radiation Monitoring System Upgrade"

3) ISAP Topic No. 2.18 " Nuclear Instrumentation Replacement"

4) ISAP Topic No. 2.19 "PCB Oil-Filled Transformers" If you have any questions concerning the attached reviews, please contact us.

Very truly yours, CONNECTICUT YANKEE ATOMIC POWER COMPANY

b. O

3. F. Opeka '

Senior Vice President

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8611120164 861030 DR ADOCK 0500 3 By: C. F. Sears Vice President (1) H. L. Thompson letter to 3. F. Opeka, " Integrated Safety Assessment Program," July 31,1985.

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Docket No. 50-213 B12296 Haddam Neck ISkP Topic No. 2.08 Loss of DC Power Study Octcber 1986

t Haddam Neck ISAP Topic No. 2.08 Loss of DC Power Study

Background

On January 2,1981, at Millstone Unit No. 2, an inadvertent trip of a 125V DC

. battery bus resulted in a reactor trip and some unpredictable plant behavior that has been the subject of close scrutiny by the NRC and Northeast Utilities (NU).

~ As a - result, . studies have been initiated to investigate the susceptibility of Millstone Unit Nos. I and 3 and the Haddam Neck plant to the same event, which could cause harmful consequences.

Project Description In response to the loss of 125V DC bus event at Millstone Unit No. 2, NU initiated a Significant Operating Experience Report (SOER). One of the recommendations of this SOER was to review the response of the Haddam Neck Plant to a partial loss of 125V DC power. Specific concerns to be examined were:

1. Turbine and generator control responses

2. Normal to reserve (auxiliary) power fast transfer control response and

3. Emergency diesel generator response to a partial loss of 125V DC power.

The principal concern of this evaluation was to determine if any single fault or operator action could prevent the control response schemes from carrying out their normal function.

CYAPCO Evaluation The loss of DC Power study contained several recommendations and conclusions.

Among these were:

o The loss of either battery at Haddam Neck does not create the types of problems experienced at Millstone Unit No. 2. This is because there is better DC bus redundancy, and there is no DC train mixing which would compromise plant integrity if either of the batteries tripped.

o On the loss of control power from battery "A", turbine trip capabilities are lost, but turbine protection is maintained by the four MSIVs failing closed which allows the turbine to gradually slow down. Hence, this type of event is not considered to be a critical concern.

o An Emergency Response Procedure to handle partial loss of DC power is needed.

Based on the above analysis, CYAPCO has concluded that a loss of DC power scenario at the Haddam Neck plant would not result in the same unpredictable plant behavior that occurred at Millstone Unit No. 2. However, an Emergency Response Procedure to handle partial loss of DC power has been drafted and incorporated into plant EOPs at Haddam Neck. Hence, CYAPCO considers this issue adequately addressed and subsequently resolved.

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Docket No. 50-213 B12296 Haddam Neck ISAP Topic No. 2.14 Radiation Monitoring System Upgrade I

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October 1986

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Haddam Neck ISAP Topic No. 2.14 Radiation Monitoring System Evaluation

' Background A number of components in the Radiation Monitoring Syst'em at Haddam Neck-are approaching the end of their useful life. The unavailability of. parts, thei

. increased: failure rates, and overall system aging and degradation,7 all have

, _ demonstrated the need for replacement.

Project Description The proposed project involves the complete' replacement nf the radiation monitoring system 'with ' a new " state-of-the-art" system. This system is designed such that each individual monitor (area or process) is an independent

. unit capable of local indication and-alarm functions. Information and control signals are communicated between the local and centralized radiation monitor-

_'ing _ systems in the control room, using a digital-based system. This is to_ be installed independent of the existing system- such -that, when ready, the new system can take over the functions of the existing system. This _ will prevent the radiation monitoring system capabilities from being compromised at any time.

~ CYA'PCO Evaluation This new radiation monitoring system will be more reliable, more efficient, and more accurate _for the intended purposes of radiation detection.- Additional _ly, the new system will likewise conform to all applicable regulatory requirements.

Further'evaluat, ion will be undertaken in the integrated assessment.

Docket No. 50-213 B12296 Haddam Neck ISAP Topic No. 2.18 Nuclear Instrumentation Replacement October 1986

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7 Haddam Neck ISAP Topic No. 2.18 Nuclear Instrumentation Replacement

Background

-The increased frequency of Licensee Event Reports (LERs) due to malfunctions

~ of'the Nuclear Instrumentation System (NIS) at the Haddam Neck plant has led to various evaluations in an > effort to resolve these difficulties. The most common, recurring problem' areas .seem to be setpoint drifts and excessive ~

noise. These have challenged ' the reactor' protection system on several occasions. 'In an effort to solve these problems, source range and intermediate range drawers were replaced as well as high voltage power supplies. However, problems continue to exist.- It is noted that the NIS is over 25 years old,' and some cable deterioration has already been noted.

Project Description Due to the importance of the NIS, the proposed project is to engineer, procure and install a completely new system. This will be done concurrent with the

. present trouble-shooting efforts.-

CYAPCO Evaluation A new NIS would enhance reliability and would also conform to current regulatory criteria for safety grade instrumentation systems including the seismic, electrical environmental qualification, and channel separation criteria.-

to the extent practical. Hence, CYAPCO is further analyzing this proposed project, and further evaluation will be undertaken in the integrated assessment.

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Docket No. 50-213 B12296 Haddam Neck ISAP Topic No. 2.19 PCB Oil-Filled Transformers October 1986

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' Haddam Neck ISAP Topic No. 2.19 PCB Oil-Filled Transformers

. Background .

Four oil-filled station service transformers currently in place in the switchgear-room at the Haddam Neck Plant not only contain PCB materials, but are also a fire hazard. The existence of PCBs poses a potential danger to the health of plant personnel, and hence ~ PCB - elimination' has become a corporate-commitment.

Project Description The proposed project is _ to replace - these PCB contaminated' Westinghouse Askerel transformers with comparable dry-type replacement units.

CYAPCO Evaluation The replacement of these transformers will enhance the1 safety of plant personnel by eliminating PCB's and by reducing potential fire risks. Hence, an expedited schedule has been proposed which should enable this replacement to be accomplished during one of the upcoming refueling outages.'_ Further evaluation will be undertaken in th'e integrated assessment.

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