ML20199C094

Requests Addl Info Related to Request to Withdraw ATWS Test Commitment for Mnps,Unit 2

ML20199C094
Person / Time
Site:	Millstone
Issue date:	01/23/1998
From:	Mcdonald D NRC (Affiliation Not Assigned)
To:	Bowling M NORTHEAST NUCLEAR ENERGY CO.
References
TAC-M99614, NUDOCS 9801290128
Download: ML20199C094 (7)

Text

. -- .. .- - _ _ . _ _ . . - - - -- -- - --

. Mr Martin L Bowling January 23, 1998 Recovery Officer Millstone Unit No. 2

. Northeast Nuclear Energy Company j clo Ms. Patricia A. Loftus Director. Regulatory Affairs P.O. Box 128 Waterford, CT 06385 i

SUBJECT:

REQUEST FOR ADDIT!ONAL INFORMATION RELATING TO THE REQUEST TO WITHDRAW AN ANTICIPATED TRANSIENT WITHOUT SCRAM (ATWS)

TEST COMMITMENT MILLSTONE NUCLEAR POWER STATION, UNIT NO. 2 (TAC NO. M99614)

Dear Mr. Bowling:

By letter dated Scptember 5,1997, Northeast Nuclear Energy Company (NNECO) requested approval to withdraw an ATWS test commitment for the Millstone Nuclear Power Station, Unit No. 2. In its letter, NNECO stated that the provisions to test one set of AC Voltage Output Low alarms, Charger Trouble alarms, and DC Bus Under Voltage alarms, at alternate refueling outages, were not implemented. Subsequently, NNECO requested withdrawal of its commitment made on July 25,1988, to conduct these teste as part of its ATWS modifications.

The staff is currently reviewing the request and has dr termined that additional information is needed to complete its review. The information needed is identified in the enclosure to this letter.

If you have any questions relating to this request, please contact me at (301) 415-1408.

Sincerely.

Originni silyni by:

Daniel G. Mcdonald, Jr., Sr. Project Manager Special Projects Office Licensing Office of Nuclear Reactor Regulation

Enclosure:

Request for Additional information ec w/ encl: See next page g; DISTRIBUTION. pl .

Docket File 3 Reading SPO Reading ab.

WTravers PMcKee LBarry DU.cDonald OGC lla <l l l ll ACRS JDurr, RI l *

• DOCUMENT NAME: G:\ANDERSEN\M99614.RAI

i. o . n.m em. ,wn, . we. . w o,. w e . cor, wasma .n. chm.nw. . r - cor, -as .n.csm.nv.nce. . u - No copy OFFICE SPO-L:PMx ARSPO-L:LAs d SPQGD NAME DMcDon56 @ LBerry \b PM(le's DATE 01@ 98 W 01M98 i 01@98 01/ /98 01/ /98 900129012e 990123 OFFICIAL RECORD COPY PDR ADOCK 05000336 ,

p PDR

i

'y p*a8og l g *-

b, UNITED STATES '

,j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. seeste4001

% , ,, , /j ,

January 23, 1998 Mr. Martin L. Bowling Recovery Officer Millstone '

Unit No. 2 Northeast Nuclear Energy Company clo Ms. Patricia A. Loftus  :

Director. Regulatory Affairs P.O. Box 125 Waterford, CT 06385

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION RELATING TO THE REQUEST TO WITHDRAW AN ANTICIPATED TRANSIENT WITHOUT SCRAM (ATWS)

TEST COMMITMENT MILLSTONE NUCLEAR POWER STATION, UNIT NO. 2 (TAC NO. Mgg614)

Dear Mr. Bowling:

By letter dated September 5,1997 Northeast Nuclear Energy Company (NNECO) requested approval to withdraw an ATWS test commitment for the Millstone Nuclear Power Station, Unit No. 2. In its letter, NNECO stated that the provisions to test one set of AC Voltage output Low alarms, Charger Trouble alarms, and DC Bus Under Voltage alarms, at attemate refueling outages, were not implemented. Subsequently, NNECO requested withdrawal of its commitment made on July 25,1988, to conduct these tests as part of its ATWS modifications.

The staffis currently reviewing the request and has determined that additionalinformation is needed to complete its review. The information needed is identified in the enclosure to this letter, if you have any questions relating to this request, please contact me et (301) 415-1408.

Sincerely, x_ $ & '

Daniel G. Mcdonald, Jr., Sr. Project Manager Special Projects Office - Licensing Office of Nuclear Reactor Regulation Docket No. 50-336

Enclosure:

Request for Additional Information cc w/ encl: See next page

/

__.__ -.- J

. l Northeast Nuclear Energy Company Millstone Nuclear Power Station

% Unit 2 cc:

Lillian M. Cuoco, Esquire

• Mr. F. C. Rothen Senior Nuclear Counsel Vice President Work Services Northeast Utilities Service Company Northeast Utilities Service Company P,0. Box 270 P. O. Box 128 Hartford, CT 06141-0270 Waterford, CT 06385 Mr. John Buckingham Ernest C. Hadley, Esquire Department of Public Utility Control 1040 B Main Street Electic Unit P.O. Box 549 10 Liberty Square West Wareham, MA 02576 New Brittin, CT 06051 Mr. D. I A. Goebel Mr. Kevin T. A. McCarthy, Director Vice President - Nuclear Oversight Monitoring and Radiation Division Northeast Utilities Service Company Department of Environmental Protection P. O. Box 128

• 7g Elm Street Waterford, CT 06385 Hartford, CT 06106 5i27 Mr. David Amerine

. Regional Administrator, Region i Vice President Nuclear Engineering U.S. Nuclear Regulatory Commission and Support 475 Allendale Road Northeast Utilities Service Company King of Prussia, PA 19406 P. O. Box 128 Waterford, CT 06385 First Selectmen Town of Waterford Mr. Allan Johanson, Assistant Director Hall of Records Office of Policy and Management 200 Boston Post Road Policy Development and Planning Waterford, CT 06385 Division 450 Capitol Avenue - MS# 52ERN Mr. Wayne D. Lanning P. O. Box 341441 Deputy Director of Inspections Hartford, CT 06134-1441 Special Projects Office 475 Allendale Road Mr. M. H. Brothers King of Prussia, PA 19406-1415 Vice President - Operations

Northeast Nuclear Energy Company Charles Brinkman, Manager P.O. Box 128 Washington Nuclear Operations Waterford, CT 06385 ABB Combustion Engineering 12300 Twinbrook Pkwy, Suite 330 Mr. J. A. Price Rockville, MD 20852 Unit Director- Millstone Unit 2 Northeast Nuclear Energy Company Senior Resident inspector P.O. Box 128 Millstone Nuclear Power Station Waterford, CT 06385

- c/o U.S. Nuclear Regulatory Commission P.O. Box 513 Niantic, CT 06307 s

i

't  ;

Northeast Nuclear Energy Company Millstone Nuclear Power Station  !

'. Unit 2 i oc:

Mr. 8. D. Kenyon -

Chief Nucler Omcor . Millstone Northeast Nuclear Energy Company P.O. Box 128 Waterford, CT 06385 i

Citizens Regulatory Commission ATTN: Ms. Susan Perry Luxton 180 Great Neck Road Waterford, CT 06385 -

Deborah Katz, President Citizens Awareness Network P. O. Box 83 Shelburne Falls, MA 03170 The Honorable Terry Concannon Co-Chalt Nuclear Energy Advisory Council _ , ,

Room 4035 Legislative Omco Building Capitol Avenue Hartford, CT 06106 '

Mr. Evan W. Woollacott Co-Chair Nuclear Energy Advisory Council  !

128 Terry's Plain Road Simsbury, CT 06070 Little Harbor Consultants, Inc.

Millstone ITPOP Project Office P. O. Box 0630 Niantic, CT 06357 0630 Mr. Daniel L Cuny Project Director Parsons Power Group Inc, 2675 Morgantown Road

- Reading, PA 19607 Mr. Don Schopfer Verification Team Manager Sargent & Lundy-55 E. Monroe Street Chicago, IL 60603 -

L

REQUEST FOR ADDITIONAL INFORMATION ATWS COMMITMENT WITHDMAWAL MILLSTONE NUCLEAR POWER STATION. UNIT NO. 2 NORTHEAST NUCLEAR ENERGY COMPANY QDCKET NO. 50 338 Rackground The ATWS Rule requires that the equipment / systems installed to prevent and/or mitigate the consequences of ATWS events be electrically independent of the existing reactor protection system (RPS) to minimize the potential for common mode failures (CMFs) that could affect both MPS and ATWS circuits. Electricalindependence of the diverse scram system (DSS) from the existing MPS should be provided from the sensor outputs up to and including the final actuation device. The ATWS design at NNECO shares a common power supply between the RPS and DSS which deviates from the staff guidance provided in the supplernentalinformation concerning electricalindependence that was published with the ATV- 9ule, in Question 2.a.2 of a letter from the NRC dated June 8,1986 Mef 1), the NRC asked NNECO to explain why a CMF affecting the RPS power distribution system, including degraded voltage and frequency conditions, that would compromise both the RPS and the ATWS prevention / mitigation functions, cannot go undetected. Also,if alarms were relied on to provide early detection of degraded voltage and/or frequency conditions, NNECO was requested to identify the specific alarms and their setpoints, along with a discussion of the periodic surveillance testing performed to verify alarm operability.

NNECO responded by stating that the Vital AC power to the four channel RPS and the four-channel DSS is supplied from four vitalinverters. These inverters are equipped with the following local and control room alarms and indications:

1. Input Breaker Trip

^

2. ' AC Voltage Output Low (Setpoint of 108 VAC)

3. AC Ground Fault

4. High Temperature (Setpoint of 175 DEG. F.)

The inverters are powered by a station 125 VDC system, which consists of 'two batteries, three battery chargers, and two battery busses. Each bus powers two inverters which in turn provide the four separate channels of vital 120 volt AC for the four channel RPS and DSS. The battery bus and battery charger systems are monitored and alarmed for various conditions including: '

1. Charger Trouble:

a. High Voltage at 150 VDC

b. Low Voltage at 120 VDC

2. DC Bus Under Voltage at 126 VDC 3.- Ground Alarms 4.'- -Indications are provided for Battery current and voltage, DC bus current and voltage.

l t

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

e 2

In summary NNECO stated that the current practice calls for testing of DC Bus Under voltage alarms at every other outage. "However, revised prucedures to be implemented at the next planned refueling outage call for testing one set of AC Voltage Output Low alarms, Charger Trouble alarms, and DC Bus Under voltage alarms at alternate refueling outages.

This revised procedure ensures that one set of these alarms are tested each outage." On September 5,1997 IRef 2), the NRC was informed that provisions to test the above alarms were not implemented and NNECO requested to withdrawal of a commitment it made on July 25,1988 (Ref 3) to conduct the above tests as part of its ATWS modifications, lasua With a common power supply between the RPS and DSS and the withdrawal of the ATWS commitment, NNECO should provided the following information to demonstrate that CMF of shared power sources will not result in loss of both RPS and DSS prevention / mitigation functions.

Quertions

1. NNECO stated that

• routine inspections performed on the various power distribution components, and the manifestation of degraded voltage and/or frequency conditions by off.

normal responses from a variety of systems and indications, thess occurrences are considered detectable."

Please verify that, based on the above statement, NNECO has the capability to detect degraoed conditions on the power distribution system without reliance on or taking credit for the alarms in question (AC Voltage Output Low alarms, Charger Trouble alarms, and DC Bus Under voltage alarms).

2. NNECO stated that: (a) Degraded conditions on a battery bus or charger would, in the worst case, impact two (out of the four) channels of both the ATWS mitigating system and the RPS and, (b) Degraded conditions on a 125 VDC or 120 Vital AC inverter or panel would,in the worst case, impact one (out of four) channels of both the ATWS mitigating system and the RPS. Neither of these occurrences would prevent the ATWS mit!' ting system (which includes the DSS) and the RPS from performing their intended furictions.

a. Please verify that the likely combination of degraded conditions on battery Bus 201B, which would impact two channels (associated with Vital Bus VA20 and VA40) and, channel A high pressurizer pressure of the RPS in bypass, will not prevent the ATWS mitigating system (which includes the DSS) and the RPS from performing their intended functions,

b. Please verify that the likely combination of degraded conditions on a 125 VDC or 120 Vital AC inverter #2 (Vital Bus VA20), which would impact logic matrices BC, BD, and CD and, channel A high pressurizer pressure of the RPS in bypass, will not prevent the ATWS mitigating system (which includes the DSS) and the RPS from performing their intended functions.

o  !

g

o.  !

- 3-  ;

REFEMNCES .

1. D. H. Jeffe letter to E. J. Mroczka, ' Millstone Nuclear Power Station, Unit No. 2, i Request for AdditionalInformation,' dated June 8,1988. l 2 M. L. Bowling, Jr., letter to U.S. Nuclear Regulatory Commission

• ATWS Modification (TAC No. 59114) Withdrawsl of Commitment,' dated September 5, '

1997. >

3. E. J, Mrocrka letter to U.S. Nuclear Reguistory Commission

• ATWS Modification )

(TAC No. 59114) ," dated July 25,1988.

I F

t I

t

- - -,a , ,. -n.., . . . , .- . - . ..,,.n..- . . - ,w.- ,. ~ , . , ,- , , , . .,, . . , _ , . , ,,., , , _- ,-,.,