3F1083-25, Forwards Info Providing Alternatives for Testing Engineered Safeguards Actuation Logic on-line.NRC Approval Requested for Removal from Actuation Sys of Components Listed in Encl

Forwards Info Providing Alternatives for Testing Engineered Safeguards Actuation Logic on-line.NRC Approval Requested for Removal from Actuation Sys of Components Listed in Encl

ML20081F859
Person / Time
Site:	Crystal River
Issue date:	10/31/1983
From:	Westafer G FLORIDA POWER CORP.
To:	Stolz J Office of Nuclear Reactor Regulation
References
3F1083-25, NUDOCS 8311040011
Download: ML20081F859 (14)

Text

-

oes M

Power coaronavsom j

October 31,1983 3F1083-25

-l 1

Director of Nuclear Reactor Regulation Attention: Mr. John F. Stolz, Chief Operating Reactors Branch #4 Division of Licensing U.S. Nuclear Regulatory Commission Washington, D.C. 20555

Subject:

Crystal River Unit 3 Docket No. 50-302 Operating License No. DPR-72 On-Line ES Actuation Logic Testing

Dear Sir:

Florida Power Corporation (FPC) is submitting this letter and its enclosure to fulfill our commitment to provide several alternatives for testing the Engineered Safeguards (ES) actuation logic on-line.

We intend to continue preliminary engineering to determine which alternative is best suited for our plant and implement the modification during Refuel V (presently scheduled for Spring 1985).

The enclosure is divided into sections titled Background, Problem, Solution, Schedule, and Summary in order to present the information to you in an organized manner. The enclosure provides a summary of three different methods for on-line ES actuation testing. These testing methods are incorporated as variations in the testing alternatives to satisfy the Technical Specification requirements. Table I to the enclosure is included to show the components which can presently be tested on-line. Equipment alignment is required to permit this testing for some components.

Table 1 also shows a list of components whose logic or method of testing must be modified to permit testing. Attachment A to the enclosure identifies components and provides a basis for removal of components from the ES Actuation System.

These components are included in this submittal so that all modifications to the ES actuation system are addressed in a coordinated manner rather than in a piece meal method.

Attachment B to the enclosure is a Conceptual Design of an Engineered Safeguard ES Matrix Blocking Circuit Schematic including an explanation of the terminology shown on the schematic. Attachment C to the enclosure is an overall schedule, including major milestones, for implementing this modification.

hO P

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- General Office 3201 Thirty-fourth Street South e P O. Box 14042 St. Petersburg. Florda 33733 813--866-5151

TO: Director of Nuclear Reactor Regulation Attention: Mr. John F. Stolz, Chief.

October 31,1983

- 3F1083-25

. Page 2 Florida Power Corporation requests from the NRC by December 16, 1983 conceptual approval for. the removal ' from the ES actuation system of the components identified in Attachment A.

Please contact me if you have any further questions.

. Sincerely, L ' 'W 7

e G. R. Westafer Manager, Nuclear Operations Licensing and Fuel Management Enclosure EMG/feb cc:

Mr. 3. P. O'Reilly Regional Administrator, Region 11 Office of Inspection & Enforcement U.S. Nuclear Regulatory Commission 101 Marietta Street N.W., Suite 2900 Atlanta, Ga. 30303

CRYSTAL RIVER UNIT 3 PROPOSED ES TESTING MODIFICATION PROGRAM I.

BACKGROUND The Engineered Safeguard (ES) System was originally designed to test all of the components in the test groups on a monthly basis.

Experience in operating the plant determined that problems occurred when specific components were tested through to the end device.

Florida Power Corporation'a December 23, 1982, letter to NRC (P. Y. Baynard to 3. P.

O'Reilly) was written to inform you that the Engineered Safeguard System could not be tested in accordance with the FSAR. Our letters to you of January 14, January 20, July 6, and July 14, 1983 requested specific changes to the Crystal River Unit 3 (CR3) Technical Specifications (Request Number 105). This request changed the frequency of manual initiation testing from

. monthly to every 18 months during shutdown to be consistent with B&W

. Standard Technical Specifications.

This request also changed the testing 4

relief for the monthly automatic actuation logic circuitry in certain portions of the ES system where testing could cause undesirable transients on plant components. A meeting was held at the NRC facilities in Bethesda on January 17, 1983 to discuss the proposed Technical Specification changes.

The NRC issued Amendment 66 to CR3 Technical Specifications subsequent

.to Refuel IV. The Safety Evaluation enclosed.with the transmittal letter granted relief through Refuel V on an interim basis and reiterated the licensee's commitment "to pursue the detailed engineering study and related redesign efforts to bring about a permanent resolution of this matter. To that end we have committed to provide a detailed schedule including the opportunity for NRC pre-implementation review by no later than October 1983".

II.

PROBLEM-The complete on-line testing of all test groups through the end devices on a monthly. basis causes problems with plant equipment that could induce transients into the operating systems. These possible events caused the plant operations personnel to refrain from testing the ES test groups containing such components.

As a result of the operating experiences and changes in operating practices, it became apparent that specific plant equipment would be required to operate and should not be isolated if the reactor building isolation signal is activated. These components consist of isolation valves for the cooling water and seal return water for the Reactor Coolant Pumps, high pressure injection pump suction valve from the make-up tank, and valves from the

. unused building spray tank. These isolation valves should be removed from the ES actuation system.

-1

Ill.

SOLUTION The enclosed proposed ES actustion system logic testing scheme will provide a permanent resolution to the logic. testing requirements and place Florida

' Power Corporation in full compliance with CR3 Technical' Specifications.

'The ES actuation system 'will be tested monthly and includes the testing of the logic up to and including'the 2 out of 3 logic paths.

. As stated above, several valves no longer require the ES actuation. signals.

Justification for the removal of the ES actuation signal is provided in Attachment A for your information and conceptual approval. These valves are included in Group B of Table I for purposes of this modification. FPC intends to formally request a Technical Specification change to the NRC to

~

remove these valves'from the ES' actuation system.

One or more of three r nods can be used to test the ES actuation logic.

They are:

1) -

Method No.1 - Test actuation logic by actuating the end device. This is the present method of testing. This method requires that system components be pre-aligned and that components be changed from one test group to another in order to provide safe operation of the actuated component under test. Group A components of Table I can use this method of testing.

2)

Method No. 2 - Test actuation logic by partial stroke of. valves or by placing a switchgear breaker in the~ test position.

Partial stroke testing of valves is accomplished by a circuit which woid change state when the valve had travelled a certain percenta3e and then

~

reverse travel to return to the original position. Pump testing is accomplished by placing a switchgear breaker in the test position to

- prevent pump surt.

(Components controlled from motor control centers cannot be tested by this ' method.) Group B components of Table I can be tested using this method.

4

- 3)

Method No. 3 - Test actuation-logic signal by blocking of final end device.

This testing is performed-in conjunction with a contact or

' device that interrupts the circuit after the 2 out of 3 logic paths are formed.' A contact or device from a test circuit device such as a relay is inserted into the circuit between the completed 2 out of 3 logic and the end device. Actuation of one of the engineered safeguard test groups causes the 2 out of 3. logic to actuate but prevents the end device from -moving. Verification circuits such as indicating lights provide : Indication to the operator that the block contact has interrupted the circuit and that the block contact has properly closed

- to restore the circuit-at the completion of the test.

Attachment B provides a-typical example for this method of testing. This method allows the test of all combinations of 2 out of 3 logic paths for all test

+

- groups. Groups A and B components of Table I can be tested using this

. method. : Present concepts for implementing this ' method include the use' of additional relay and indicator light cabinets or the use of microprocessors and microcomputers.,

t.

~.- -. _ -.~,-

In order to ' test the ES system by this method through to. the end

' device, additional testing will be done during refueling.. This test will consist of inducing an actuation signal at the-sensor to cause a full system actuation through at least ; one combination of the 2 out of 3 logic paths, and actuation of the end device. This test assures the integrity of the cables from the sensor to the' end device. Since these cables are passive devices, failure ~ of cables are not expected.

Therefore, this test would not have to be accomplished as often as tests for active devices.

ES end devices are tested in accordance with 10 CFR 50.55 (ASME XI Pump and Valve Test Program).

This' program. tests pumps on a

!~

monthly basis and, based on the removal of the sixteen (16) valves in

. Attachment A, more than 90% of the actuated valves on a quarterly basis. A'small number of. valves are tested during cold shutdown and only two valves are tested during refueling.

From'these methods of testing the ES actuailon logic, FPC has developed alternatives to implement the testing of the ES actuation system. FPC is performing preliminary engineering for these alternatives to establish firm design bases and hardware requirements. Based on a thorough evaluation of the preliminary engineering, FPC will select the best alternative for final

. design and implementation at Crystal River Unit 3. The alternatives are:

1)

Alternative No.1: This alternative uses a combination of test methods

'I and 2. The ES components that will be tested by actuating the end device (Method 1) are shown in Table 1, Group A. The ES componentt which will be modified to allow testing of the ES actuation logic by partiet stroking of valves or placing switchgear breakers in the test-postSon (Method 2) are shown in Table 1, Group B.

2)

Alternative No. 2:

This alternative uses a combination of test

-methods 1 and 3. The ES components which will be tested by actuating

[

the end device (Method.1) are shown in Table 1, Group A.

The ES i

components which will ba modified to permit testing.by blocking the end device (Method 3) are ahown in Table 1, Group B.

- 3) '

Alternative No. 3:

This alternative uses only Method 3.

All components (Table 1, Groupa A & B) will have their actuation circuitry

[

modified to allow testing of the ES matrix without operating the end

[

device. The end device will be tested during refueling and through the i;

operation of the components which are included in the ASME Section

.XI test program (IST program).

i '

.IV.

SCHEDULE i

A schedule has been developed (Attachment C) for implementation of the ES p

. Actuation ' System Testing Modification by the end of Refuel V.

Test

[

methods I and 2 are presently being utilized by FPC to effect present ES L

~ actuation testing and, therefore, are NRC approved methods. Test method

(

3 is a new concept in ES testing to be utilized at CR 3. In addition, FPC L

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,__..._._.__.a._...______.

. _ _.,... - ~ _ _.. _. -

- requests your conceptual approval to remove the components described in Attachment A from the ES actuation system by December.16,1983. FPC -

will implement the attached schedule and further detailed information on

.the alternative' selected will;be provided to the NRC by January 31, 1984.

Because Method 3 could best-be Implemented in different ways for :

Alternatives 2 and 3, the detailed design cannot be completed until the best alternative is selected. For example, Alternative 2 could be implemented

' using additional relays and Alternative 3 could be implemented using a microprocessor.

Pursuant to. your conceptual approval of removing the components in Attachment A from the ES actuation logic, FPC will submit a Technical Specification change to the NRC' which reflects this revision.

Upon approval of.the Technical Specification change and subsequent plant modification, the FSAR change will be submitted.

. V.

S_UMMARY Florida ~ Power Corporation requests your conceptual approval for the removal;of the-components described in' Attachment A from the ES actuation system - by. December 16, 1983 in order to meet the proposed schedule.

Pursuant. to your conceptual. approv'al for the above, Florida Power Corporation will' provide further detailed information on the testing

. alternative selected by January 31,1984.

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. _4_

5

TABLE 1 TABLE OF COMPONENTS ON-LINE ES ACTUATION TEST

SUMMARY

GROUP A TEST

• GROUP B TEST ON-LINE BY ON-LINE OR BLOCKED PARTIAL STROKE OR BLOCKED END DEVICE -

END DEVICE 3ESAR WDV-405 AHV-1A BSV-36

• 3ESBR WDV-406 AHV-1B BSV-37,*

AHF-15A WDV AHV-IC MUV-253

• AHF-15B WDV-61 AHV-ID MUV-258 *

' AHF-1A' WDV-62 BSP-1A MUV-259

• AHF-1B WDV-94 BSP-1B MUV-260 *

' AHF-lC WSV-3 BSV-16 MUV-261 *

~ CAV-1 WSV-4 BSV-17 MUV-64

• CAV-126 WSV-5 BSV-Il SWV-79

• CAV-2 WSV-6 BSV-12 SWV-80

• CAV-3 BSV-3 SWV-81

• CAV-4 BSV-4 SWV-82

• CAV-5 DHP-1A SWV-83

• CAV-6 DHP-1B SWV-84

• CAV-7 DHV-5 SWV-85 *

~ CFV-Il DHV-6 SWV-86 *

- CFV-12 EDG-A CFV-15 EDG-B CFV-16

- MSV-130 CFV-25 MSV-148 CFV-26 MUP-1A CFV-27 MUP-1B CFV-28 M UP-IC CFV-29 MUV-23 CFV-42 MUV-24 CIV-34 MUV-25 CIV-35 MUV-257 CIV-40 MUV-26 CIV-41 MUV-27 DCP-1A MUV-40 DCP-1B MUV-41 DHV-34 M UV-49 DHV-35 MUV-53 DWV-160 -

SWV-109 EFP-1 SWV-110 MUV-58 SWV-47 MUV-73 SWV-48 RWP-2A SWV-49 RWP-2B SWV-50 RWP-3A UVLO RWP-3B SWP-1A

• Valves to be removed from ES SWP-1B actuation system upon NRC approval.

SWV-12 SWV-151 SWV-152

SWV-353 SWV-354 SWV-355 WDV-3 WDV-4

/

.~

m ATTACHMENT-'A

~

1 BASIS FOR. REMOVAL OF ES~ ACTUATION'FROM COMPONENTS 1.

Function' ~

Reactor Coolant Pump Seal Return and Motor. Cooling Isolation Valves c

!Co'apon'ent Tag Numbers MUV-253, ~ MUV-258,' MUV-259, MUV-260, MUV-261, SW-79, SW-80, SW-81,. SW-82, "1

~

- SW-83, - SW-84,. SW-85, - and SW-86 Discussion-TThe' orig'inal design for control of the reactor coolant pumps and their auxili-aries had.the following as a basis:

a.

The reactor coolant Epumps were not required for any post-accident ' condi'-

tions. :

Lb. LThe. pumps could be' operated'for indefinite periods'of time with either

. the seal injection.or the: jacket cooling.-

c.- Momentary isolation-of the pump motor cooling was acceptable.

[The above basis made it fappropriate to have. the seal injection, seal return, i and jacket cooling / motor cooling lines. penetrating the Reactor. Building, be

~ eauipped with isolation valves automatically-actuated. by.the Engineered. Safe-

't

' guard System; Reactor" Building. Isolation Signal.

Since the original design assumed.that the' reactor coolant pumps.could be operated with either seal in-

' jection or jasketi cooling, ' testing during power operation could be implemented

~

Eby testing the pump' seals and jacket / motor. cooling isolation valves at differ-e

~

~

ent times, as outlined in Regulatory Cuide 1.22.

LThe TMI-2" lessons; learned and experienced operational difficulties with the

. reactor coolant pump seals 1have negated the original basis for the controls of the isolation valves casociated with the seal injection, seal return, and jacket cooling.-

-Presently. the reactor coolant pumps may.be required to operate following'a j

1small. break LOCA.' LFor reliable operation of the pumps, it-is recommended

that seal injection and jacket cooling not be. perturbed during power operation.-

P Previous concern about ope' ration of the seals has resulted in an approved modification to remove the ES signal from the seal-injection isolation valve (HUV-18);. leaving only'the seal return and jacket cooling to be further anal-

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yzed.

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ATTACHMENT

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• It is important to note that, presently, should a small break LOCA occur during a channel test, a single failure could prevent operation of all reactor coolant pumps since either "A" or "B" channel actuation will isolate the seal return, jacket cooling, and motor cooling. The probability of such a scenario is not negligible considering the frequency, number, and duration of channels tested together with the probability of failures of a channel.

Also, from engineering judgement, it would appear that the probability of a small break LOCA is higher than a large break LOCA, thereby increasing the probability of operating the reactor coolant pump post-accident.

Analysis / Accommodation Considering the new design basis for the reactor coolant pumps and its auxili-aries, together with occurrences of false actuations of the Engineered Safe-guard System, it is not appropriate to automatically isolate the reactor coolant pump seal return and jacket cooling or to test the closure of the isolation valves during plant operation. Manual operator closure of the valves from the control room assures a greater availability of the reactor coolant pumps.

Manual closure of the isolation valves, associated with the seal return, does not decrease-the Reactor Building integrity since:

a.

The reactor coolant pump seals serve as a barrier between the reactor coolant syster and the make-up and purification system.

b.

The seal return flow is small, and consists only of make-up water from seal leak off.

c.

The make-up and purification system is a closed system designed to handle radioactive effluent.

Not having automatic closure of the isolation valves, associated with the jacket cooling / motor cooling, does not decrease the Reactor Building integrity since:

Jacket cooling / motor cooling is not directly connected to either the a.

reactor coolant system or the Reactor Building atmosphere.

b.

The nuclear service closed cycle cooling system is kept at a pressure higher than the Reactor Building pressure precluding out-leakage.

c.

Inlet and outlet lines are equipped with flow instrumentation to detect and alert the operator of excessive leakage.

7,_

ATTACID4ENT A

, Considering the operational requirements, the post-accident requirements, and the impact on Reactor Building isolation capabilities, removal of the Engineered Safeguard System Reactor Building Isolation Signal is requested on the following valves:

Seal Return Jacket Motor Cooling MUV-258 SWV-82 and SWV-86 MUV-259 SWV-81 and SWV-85 MUV-260 SWV-80 and SWV-84 MUV-261 SWV-79 and SWV-83 MUV-253 2.

Function Former Sodium Make-Up Tank Isolation Valves Component Tag Numbers BSV-36 and BSV-37 Discussion Sodium thiosulphate has been deleted as an agent in the Reactor Building spray solution. The former sodium thiosulphate tank is currently used for addition of sodium hydroxide into the spray, and the former sodium hydroxide tank has been spared.

The discharge of this spared tank includes two (2) motor operated valves (BSV-36 and BSV-37)..which are automatically actuated via the Engineered Safeguard Actuation System Reactor Building Isolation Signal. The modification to the tank's function has not included the removal of the Engineered Safeguard signals.

Recommendation Since the tank is spared, and does not perform any safety functions, the iso-lation valves from the tank are maintained in a closed position. The Engineered Safeguard signals could be removed without decreasing the integrity of the Reactor Building spray system. Testing of the valves is not required.

3.

Function Make-Up Tank Isolation Valve Component Tag Number MUV-64

ATTACHMENT

/s

. Discussion Due to tight tolerances,_the availability of the multi-stage HPI/make-up pumps,:during normal plant operation or emergencies, is strongly dependent on the availability of an adequate source of water supply from either the make-up tank or.the borated water storage tank (BWST).

During normal operation, the pumps are. lined up with the make-up tank via Valve MUV-64. Experience has shown that unanticipated closure of MUV-64 results in failure of the operating HPI/make-up pump in a very short period of time.

Inappropriate pump line-up can result'from either false actuation of the Engineered Safeguard Actuation System (ES) during normal plant oper-ation or during emergencies with a bonified ES switchover from the make-up tank to the BWST should the BWST valve stick closed isolating all suction paths to a given pump.

In this latter case, the pump would have failed even though appropriate delayed manual line-up could be obtained via manual re-mote operation or hand wheel operation =of the BWST suction valves, thus reducing the post-accident availability of the make-up pumps for emergency core cooling.

The original design of the controls for MUV-64 included features to permit Epartial stroke during ES testing; however, these features have been demon-strated.as inappropriate.

Analysis /Re'c'ommendations Since plant operation has demonstrated the sensitivity and the unreliability of the HPI/make-up pumps to a loss of suction, it is not appropriate to close MUV-64 with an Engineered Safeguard Actuation Signal or to test the closure of the valve during plant operation. I Increased pump availability could be provided by permitting manual closure of the valve frem the control room.

Manual closure of Valve MUV-64, while increasing the availability of the make-up pumps, does not lead to a decrease in emergency core cooling capabili-ties since:

Preliminary calculations show that the operator has a minimum of five (5) a.

minutes to several hours to close MUV-64 before a' low level in the make-up tank alone or. the combination of make-up tank and BWST, simultaneously, will occur.

b.

In case of an emergency, the HPI/make-up pump is protected against a failure of the piping in the discharge of the make-up tank by a check valve preventing back flow of borated water from the BWST, thus maintain-ing the integrity of the. safety classification break between the HPI system and the make-up system.

c.

A low level alarm and level indicator are provided in the control room to alert the operator of a low level condition in the make-up tank.

~

~..

ATTACHMENT A-j._.

5-Considering the operational experience and resulting improvement in avail-

~

ability of, the HPI/make-up pump, it is requested that the ES signal be re-mov,ed from MUV-64.-

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ATTACHMENT D

CONCEPTUAL DESIGN OF ENGINEERED SAFEGUARD ES MATRIX BLOCKING CIRCUIT SCHEMATIC

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,2, I I I I I

3 1 1 I i 1 I ii 2

3 ll ll MANUAL f I I l NORMAL n

MONITOR BLOCKING TEST POWER SUPPLY DEVICE h MONITOR v

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END DEVICE VALVE, MOTOR, DAMPER dTC.

The schematic shown above is an example of a block circuit design to permit testing of the

{

logic only as described in Method 3. The typical ES matrix is used in many applications within l

the ES system. The block device is not specifically identified since the specific device could be a relay or other device. The monitors are indicating lights or other devices to inform the l

operator that the circuit is in the test position and has returned to the normal configuration when the test is completed.

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