A05034, Forwards Addl Info Re Manual Trip of Reactor Coolant Pumps, Per NRC Request.Westinghouse Owners Group Methodology Being Used on Interim Basis Until Revised Small Break LOCA Analysis Approved by NRC

Forwards Addl Info Re Manual Trip of Reactor Coolant Pumps, Per NRC Request.Westinghouse Owners Group Methodology Being Used on Interim Basis Until Revised Small Break LOCA Analysis Approved by NRC

ML20212M607
Person / Time
Site:	Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png
Issue date:	03/05/1987
From:	Mroczka E CONNECTICUT YANKEE ATOMIC POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
TASK-2.K.3.05, TASK-TM A05034, A5034, NUDOCS 8703120094
Download: ML20212M607 (6)

Text

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e' w CONNECTICUT YANKEE ATOMIC POWER COMPANY BERLIN, CO N N ECTIC UT P. O. BOX 270 64ARTFORD. CONNECTICUT 06101 Taterwont 203-686 6911 March 5,1987 Docket No. 50-213 A05034 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, D.C. 20555 Gentlemen:

Haddam Neck Plant Response to Generic Letter 85-12 Manual Trip of Reactor Coolant Pumps By letter dated June 28,1985,(I) the NRC Staff issued Generic Letter 85-12, transmitting a Safety Evaluation which concluded that the information provided by the Westinghouse Owners' Group (WOG) submittals on Reactor Coolant Pump (RCP) alternate trip criteria was acceptable on a generic basis. Additional plant-specific information was also requested in that letter to address NRC Staff concerns about Instrumentation selection and uncertainties, and operator training and procedures.

Initially, a response to this generic letter was determined not to be required based on the fact that the WOG methodology was not endorsed by the Connecticut Yankee Atomic Power Company (CYAPCO) and that our docketed, but not yet approved, small break LOCA analysis indicated that a RCP trip may not be required. However, in September of 1986 upgraded Emergency Operating Procedures (EOPs) were implemented that used the WOG methodology to determine RCP trip criteria. The WOG methodology is being used on an interim basis, until the revised small break LOCA analysis is approved by the NRC. At such time as approval is provided, and an acceptable basis exists for not requiring a RCP trip, CYAPCO's position will no longer rely on the WOG methodology and changes to the EOPs will occur.

CYAPCO hereby provides the attached information for the Haddam Neck Plant in response to the NRC Staff's requeat. This information should fully resolve TMI Action Item 3.K.3.5 and Generic Letters83-10c,83-10d, and 85-12.

(1) Hugh L. Thompson's letter to All Applicants and Licensees with Westinghouse Designed Nuclear Steam Supply Systems, " Implementation of TMI Action Item II.K.3.5., ' Automatic Trip of Reactor Coolant Pumps' (Generic Letter 85-12)," dated June 28,1985.

8703120094 870305 j g

PDR ADOCK 05000213 P PDR

IJ.S. NuclL:r 'Rigulat:ry 'C::m:nission A05034/Page 2 -

. March 4,1987 If you have any questions, please contact us.

Very truly yours, CONNECTICUT YANKEE ATOMIC POWER COMPANY -

M'_ /

E.3.yoczka /

Senior Vice President 1 l-

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A05034/P g21 of 4 '

HADDAM NECK PLANT ADDITIONAL INFORMATION ON

- MANUAL TRIP OF REACTOR COOLANT PUMPS A. Determination of RCP Trip Criteria

1. Identify the instrumentation to'be used to determine the RCP trip set point, including the degree of redundancy of each parameter signal needed for the criterion chosen.

Response

Reactor Coolant System (RCS) pressure has been selected as the parameter to be monitored for determining when the Reactor Coolant Pumps (RCPs) should be tripped. The Haddam Neck Plant has two wide range (0-3000 psig) pressure channels which operators will monitor to determine if tripping the Reactor Coolant Pumps is necessary.

2. Identify the instrumentation uncertainties for both normal and adverse containment conditions. Describe the basis for the selection of the adverse containment parameters. Address, as appropriate,

-local conditions such as fluid jets or pipe whip which might influence the instrumentation reliability.

Response

The RCS wide range pressure transmitters are located inside containment. Following a design basis accident, these transmitters would be subjected to high temperature, high humidity, high pressure and high radiation and are qualified for the applicable conditions.

Instrument loop uncertainties were determined for both normal and adverse containment conditions. These loop uncertainties include all the uncertainties associated ~ with the loop such as calibration uncertainty and instrument drift. The effects of temperature and radiation were also included in the adverse containment uncertainties. The loop uncertainties were 87 psi for normal containment and 345 psi for adverse containment.

Potential fluid jets or pipe whip effects were reviewed for their impact on the transmitters. The result of this review was that there are no high energy lines within 10 feet of the transmitters and the design basis environmental qualification envelope would bound the local conditions for any pipe break.

3. In addressing the selection of the criterion, consideration to uncertainties associated with the WOG supplied analyses values must be provided. These uncertainties include both uncertainties in the computer program results and uncertainties resulting from plant-specific features not representative of the generic data group.

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' ?A05034/Paga 2 cf 4 If a licensee determines that the WOG alternate criteria are marginal

' for preventing unneeded RCP trip, it is recommended that a more Ldiscriminating plant-specific procedure.be developed.. For example, use of the NRC-required inadequate-core-cooling . instrumentation may take be useful credit for to

'allindicate equipment the need for 'RCP trip).

(Instrumentation Licensees available should to the operators for which the licensee has sufficient confidence that it will -

be operable during the expected conditions.

-- Response: -

The- manual RCP trip setpoints used in the emergency operating procedures were determined utilizing the WOG methodology. The-calcylated trip setpoints are 1150 psig and 1380 psig for normal and adverse - containment conditions,' _ respectively. The non-LOCA accidents discussed in the (DSA and the CYAPCO letter of June 30, 1986 to the NRC Staff (Il were reviewed to determine if these setpoints are acceptable to prevent inadvertent and unneeded RCP -

trip. The-only non-LOCA design basis transient for which manual RCP trip will occur is the steam line break (SLB) transient. In the SLB . transient, however, the consequences are more severe if: the RCPs are not tripped. Therefore, it was concluded that the use of an RCS wide range pressure setpoint provides sufficient discrimination l~ to prevent unneeded RCP trip.

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B. Potential RCP Problems

1. Assure that containment isolation, including inadvertent isolation,

-will not cause problems if it occurs for non-LOCA transients and accidents,

a. I)emonstrate that if water services needed for RCP operations are terminated, they can be restored fast enough once a non-LOCA situation is confirmed to prevent seal damage or failure,

b. Confirm that containment isolation with continued pump operation will not lead to seal or pump damage or failure.

Response

A containment isolation signal will not interrupt the flow of seal water to the RCPs or the flow of component cooling water to the RCP oil cooler and the thermal barrier. Automatic closure of associated valves upon containment isolation was eliminated in 1980 and thus water services are not terminated to the RCPs upon containment isolation. Therefore, a containment isolation signal will not, in itself, lead to seal or RCP damage.

(1) 3. F. Opeka letter to C. I. Grimes, dated June 30, 1986,

Subject:

Reanalysis of non-LOCA Design Basis Accidents.

h A05034/ Pag 3 3 cf 4 '

21- Identify the components required to trip the RCPs, including relays",

power supplies and breakers. Assure thatLRCP trip, when determined

. to be necessary, will occur. If necessary, as a result of the location g of any critical component, include the effects of : adverse -

' containment conditions on RCP trip reliability. Describe the basis

( ~: for the adverse containment parameters selected.

!- Response:

The electrical components required to trip reactor coolant pump P-17-1 when a manual trip of the pump is initiated-from the control ~

room is as follows:

-- Circuit breaker,4,160V SWGR Unit 31' Circuit breaker, cell switch 52H

- Circuit breaker, control switch 1/Pl7-1 Circuit breaker, trip coi! "TC"

-- Circuit breaker, auxiliary contact "a" 125V control cable Pl71P1 125V control cable P171T 25A fuses 125V DC supply Identical sets of electrical components are required to trip RCP Pl7-2, Pl7-3 and Pl7-4.

The above components are located either in the Control Room or Switchgear Room, areas of mild environment, and therefore are not sub.iect to adverse environmental conditions following an accident.

RCP trip . reliability is therefore not impacted ' by adverse containment conditions and RCP trip, when determined necessary, should occur.

C. Operator Training and Procedures (RCP Trip)

-1. Describe the operator training program for RCP trip. Include the general philosophy regarding the need to trip pumps versus the desire to keep pumps running.

~ Response:

The existing reactor coolant pump lecture for reactor operators includes a section dedicated to " emergency shutdown of a reactor coolant pump." This section includes the criteria for RCP operations following a reactor trip. During lessons on each related casualty, the response of the plant is discussed with and without RCPs running.

The general philosophy provided to the operators is identical to the WOG philosophy on pump trip criteria. However, the trip criteria set forth in the new emergency procedures provide the operator more latitude to keep the RCPs running when needed. These procedures are more realistic than the WOG general philosophy of trip criteria.

In addition, the procedures dictate that operators are to start an RCP to get some water into the core as a last resort.

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- A0'5034/Pfg2 4 cf 4;

. 2. -Identify those procedures which include RCP trip related operations:-

la. RCP trip using WOG alternate criteria

b. RCP restart-c.' Decay heat removal by natural circulation

d. Primary system void removal e.,  :-.Use' of steam generators with and without RCPs operating

f. . _ RCP trip for other reasons

- Response:

The following is a list of the procedures that relate to RCP ' trip .

operations:

1. E-0 -(Reactor Trip or Safety Injection)

2. 'E-1 (Loss of Reactor or Secondary Coolant)-

3. E-3 (Steam Generator Tube Rupture)

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-4. ECA-2.1 (Uncontrolled Depressurization of all Steam Generators)

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