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'o UNITED STATES 7.
NUCLEAR REGULATORY COMMISSION AEOD/E122 WASHINGTON, D. C. 20555. --
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.This.is an_ internal, pre-
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- 'SEP' 4 1981 decisional document not necessarily representing a position of AE0D or NRC.
MEMORANDUM FOR:
Carlyle Michelson, Director Office for Analysis and Evaluation of Operational Data FROM:
Harold Ornstein Office for Analysis and Evaluation of Operational Data
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SUBJECT:
AEOD CONCERN REGARDING INADVERTANT OPENING OF ATMOSPHERIC DUMP VALVES ON B&W PLANTS DURING LOSS OF ICS/NNI POWER In a memo of May 21, 1980 (reference 1), I pointed out the subject concern.
I prepared a May 23, 1980 memo (reference 2) to Harold Denton bringing this concern to his attention.'
In the past I have informed you of actions being ~taken by NRR and the licensees to correct this ' problem.
I am pleased to provide you' with a recent SER for TMI-l which describes t.ha modification which was made to correct the subject design deficiency.
pp Harold Ornstein Office for Analysis and Evaluation of Operational Data
Enclosures:
As stated cc: w/ enclosures C. J. Heltemes, Jr.
J. Pellet R. Becker AEOD Lead Engineers p
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,1 Reference 1: Memo H. Ornstein to C. Michelson, " Lessons Learned From the February 26, 1980 Crystal River Transient," May 21,~1980.
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Reference 2: Memo C. Michelson to H. R. Denton, " Lessons Learned From t e Crystal River Transient of February 26, 1980 - Correcting Atmospheric Dump Valve Opening Upon Loss of ICS Power "
May 23,1980.
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,, ua UNITED STATES o,,
' NUCLEAR REGULATORY COMMISSION
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E WASHINGTON, D. C. 20555
- -August. 28,1981
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Docket No. EO-289
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Mr. Henry D. Hukill, Vice President and Director - TMI-l Metropolitan Edison Company P. O. Box 480 Middletown, Pennsylvania _17057
Dear Mr. Hukill:
We have reviewed your description of the pmposed modifications pre-venting the automatic opening of the atmospheric dump valves (ADVs) upon loss of non-nuclear instrumentation power su21, 1981 (TLL 671)pply w mitted by letter dated Januhry Your submittal is in response to our letter dated August 15, 1980 which discusses our concerns regarding the automatic opening of the ADVs that results in aggravating overcooling transients.
We, find that your proposed modification resolves o'ur concerns and therefore is acceptable. Our evaluation of your proposed modification -
cons.iders your commitment to revise the administrative controls that
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requires a test of the manual backup channel every six months during plant operation.
A copy of our Safety Evaluation Report is enclosed.
Sincerely, Jo n. Stolz, Chief erating Reactors Branch #4 Division of Licensing
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Enclosure:
Safety Evaluation Report' cc w/ enclosure:
See next 3 pages Q'dOb.
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Metropolitan Edison Company '
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.cc w/ enclosure (s):
Mr. Marvih I'. Lewis- -
Dr. Walter.H. Jordan 6504 Bradford Terrace 881 W. Outer Drive Philadelphia, Pennsylvania.19149 Oak Ridge, Tennessee 37830 Walter W. Cohen, Consume.- Advocate
.S.. Linda h. Little Department of Justice 5000 Hermitage Drive Strawberry Square;,14th Floor Raleigh, North Carolina 27612 Harrisburg, Pennsylvania 17127 Ms. Gail P. Bradford
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Robert L. Knupp, Esq.
Anti-Nuclear Group Representing Assistant Solicitor
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'. --< e Knupp and Andrews 245 W. Philadelphia Street P. O. Box P York, Pennsy,1vania 17404 407 N. Front Street Harrisburg, Pennsyl,vania 17108 John Levin, Esq.
Pennsylvania Public Utilities Comm.
John E Minnich~, Chairman Box 3265 Dauphin Co. Board of Commissioners Harrisburg, Pennsylvania 17120 Dauphin County. Courthouse F.ront and. Market Streets Jordan D. Cunningham, Esq.
Harrisburg, Pennsylvania 17101 Fox, Farr and Cunningham 2320-North 2nd Street
- Atomic Safety a'nd Licensing Appeal Board Harrisburg,. Pennsylvania 17110~
. U.S. Nuclear Regulatory Commission Washington, D. C.
20555 Hs. Louise Bradford TMIA
- Atomic Safety and. Licertsing Board Panel 1011 Green Street U.S. Nuclear P'gulatory C'omdission Harrisburg, Pennsylvania 17.102 e
Washington, D. C.,205.55 Ms. Marjorie M. Aamodt
- Docketing and Service Section _
R.D. !5 U.S. Nuclear Regulatory. Commission Coatesville, Pennsylvania 19320 Washington, D. C.
20555 Ms. Karen Sheldon Robert Q. Pollard Sheldon, }!armon &. Weiss 609 Montpeller' Street 1725 I Street, N.W. - Suite 506 Baltimore, Maryland 21218 Washington, D. C.
20006 Cha'uncey Kepford Earl B. Hoffman '
Judith H. Johnsrud Dauphin County Commissioner Environmental Coalition on Nuclear Power Dauphin County Courthouse 433 Orlando Avenue Front and Market Streets State College, Pennsylvania 16801 Harrisburg,. Pennsylvania 17101 Ms. Ellen R. Weiss, Esq.
Sheldon, Hr.rmen & Weiss 1725 I Street, N.W.
Suite 506 Washington, D. C.
20006 Mr.--Steven C. Sholly Mrs. Rhoda D. Carr 1402 Marene Drive linton of Concerned Scientists 1725 I Street, N. W., Suite 601 Harrisburg, Pennsylvania 17109 Washington, DC 20006
Metropolitan Edison Company -
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Mr. Thomas Gerusky Ms. Jane Lee Burea'u of Radiation" Protection -
R.D;- 3, Box 3521' Department of Environmental Resources Etters, Pennsylvania 17319 P. O. Box 2063 Harrisburg, Pennsylvania 17120 Karin W. Carter, Esq.
505 Executive House P. O. Box 2357
<Harrisburg, Pennsylvania 17120 '
Honorable Mark Cohen 512 0-3 Main Capital Building Harrisburg, Pennsylvania 17120 G. F. Trowbridge, Esq.
Dauphin County Office Emergency Shaw, Pittman, Potts & Trowbridge Preparedness 1800 H Street, N.W.
Court House, Room 7 Washington, D. C.
20036 Front & Market Streets Harrisburg, Pennsylvania 17101 Mr. E. G. Wallace Licensing Manager Department of Environmental Resources GPU Service Corporation ATTN: Director, Office of Radiological 100 Interpace Parkway Health Parsippany, New. Jersey 07054 P. O. Box 2063 Harrisburg, Pennsylvania 17105 Ms.~Lennie Prough U. S. N. R. C. - Till Site P. O. Box 311
.Middletown, Pennsylvania 17057 Ms. Virginia Southard, Chairman Citizens for a Safe Environment 264 Walton Street Lemoyne, Pennsylvania 17043 Mr. Robert B. Borsum Babcock & Wilcox Government Publications Section Nuclear Power Generation' Division State Library of Pennsylvania Suite 420, 7735 Old Georgetown Road Box 1601 (Education Building)
Bethesda, Maryland 20014 Harrisburg, Pennsylvania 17126
- Ivan W. Smith, Esq.
Mr. David D. Maxwell, Chairman Atomic Safety & Licensing Board Panel Board of Supervisors U.S. Nuclear Regulatory Commission Londonderry Township Hashington, D. C.
20555 RFD!1 - Geyers Church Raod Middletown, Pennsylvania 17057 Ms. Kathy McCaughin Three Mile Island Alert, Inc.
23 South.21st street Regional Radiation Representative Harrisburg, Pennsylvania 17104 EPA Reoion III Curtis' Building (Sixth Floor)
Mr. C. W..Smyth,
6th and Walnut Streets Supervisor of Licensing TMI-l Philadelphia, Pennsylvania 19106 Metropolitan Edison Company P. O. Box 480 Middletown, Pennsylvania 17057 e
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Metropolitan Edison.C'ompany Mr. R. J. Toole Allen R. Carter, Chairman Manager TMI Joint Legislative Committee on Energy Metropolitan Edison Company P. O. Box 142 P. O. Box 480 Suite 513 Middletown, Pennsylvania 17057
_ jenate Gre,ssette Building Columbia, South Carolina 29202 Daniel M. Pell, Esq.
ANGRY 32 South Beaver Street York, Penit,3yTvan'ia '17401 Nilliam5." Jordan,III,Esq.
Harmon & Weiss 1725 I Street, NW, Suite 506 Washington, DC 20006 J. -B. L-ieberman, Esq.
General Counsel Federal Emergency Management Agency Berlock, Israel & Liberman 26 Broadway ATTN: Docket Clerk New York, NY 10004 1725 I Street, NW Washington, DC 20472 York College of Pennsylvania
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Country Club Road York, Pennsylvania 17405 Mr. Donald R. Haverkarnp
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Senior Resident Inspector (TMI-1)
U.'S. N. R. C, P. O. Box 311 Middletown, Penr.sylvania 17057 Mr. Richard Roberts The Patriot i
812 Market Street i
Harrisburg, Pennsylvania 17105 p
and Developm::nt ATTN: Coordinator, Pennsylvania State Clearinghouse P. O. Box 1323 Harrisburg, Pennsylvania 17120
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,,., UNITED STATES.
NUCLEAR REGULATORY COMMISSION g
- g WASHINGTON, D. C. 20555 3
SAFETY EVALUATI0fl BY THE OFFICE OF NUCLEAR REACTOR REGULAT OH-i SUPPORTING THE ACTION TAKEN TO H0DIFY THE CONTROLS FOR TH5 STEAM' DUMP METROPOLITAN EDISON C0!1PANY JERSEY CENTRAL POWER AND LIGHT C0f1PANY PENI45YLVAllIA ELECTRIC COMPANY THREE MILE ISLAND NUCLEAR STATION,' UNIT NO.1 DOCKET NO. 50-289 Introduction Our review of the Crystal River Unit No#. 3 (CR-3) event of February 26, 1980, revealed that failure of the non-nuclear instrumentation (NNI) or the integrated control system (ICS) power supply can result in spuriously opening the atmos-pheric steam dump valves to a 50% position. Such an anomaly could significantly
.By letter dated aggravate an overcooling transient of the primary) system.
August 15, 1980 we informed Met Ed (the licensee of our concern that on THI-1 upon loss of ICS p6wer supply, the ADVs automatically open to a 50% position.
a similar anomaly to the CR-3 occurrence.
In response to our concerns, the
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licensee by letter dated January 21,1981 (TLL 671) discussed his plant design and proposed nodifications to avoid this anomaly.
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Discussion & Evaluation _
The licensee's review of his design confirms tha't upon loss of. ICS " Hand Power" the ADVs will open to the mi.dscale positon. To eliminate this situation, the licensee proposed to install a manual control channel for the ADVs which will automatically switch in upon loss of ICS " Hand Power". The manual control channel consists of a " manual loader", a voltage-to-current (E/I) converter, and a lock-out loss-of-voltage relay.
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The " manual lo: der" contains a thumb wheel' for the operstor to se1ect any position from 0 to 100% open and a meter indicating the, output control signal to l
the ADVs. Administritive controls will require that the manual loader be set to 0% open. Thus, when ICS " Hand Power" is lost, the manual control will switch in automatically and it will be pre-selected to keep the ADVs in the closed
. position. The manual loader receives its +24 VDC input power, from an' existing DC power supply 1 the DC power source originates from the 120 VAC " Computer Bus".
The selected voltage-to-current converter receives a -10 to +10 VDC signal from the manual loader and provides a corresponding 4-20 mA output current.
l This E/I converter is a Moore Type SCT, which does not have built-in provisions to test (measure) its output current. The E/I converter receives 120 VAC input power, from a comon circuit breaker on the " Computer Bus", that pro-
,l vides input power.(120 VAC/24 VDC) to both the E/I converter and the manual l
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A basic concern is that loss of control power could result in the ADY opening to the midscale position. The ICS " Hand power" has many alternate sources but normally obtains power from inverter "1A".which is,part of Division "A" of the Class 1E power system. The proposed manual control channel will obtain its power from the " Computer Bus".
This bus obtains power nonna11y from in-verter "1E", which obtains its AC and DC inputs from Division "A" also. Between the inverter "1E" and the Computer Bus is a static transfer switch which pro-vides automatic fast transfer capability to a regulated (Solatron) AC bus in -
the other' Division of the Class 1E power system.
B'ased on our review of the proposed modificabon that utilizes the " Computer Bus" as an input power source for the manual control channel is sufficiently independent to reduce the likelihood of loss of both the automatic ICS and the manual control channel for assuring proper operation of the ADVs. On this basis, we find the " Computer Bus" power supply as an alternate power source is-acceptable.
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Our review also showed that loss of the 24 VDC power supply, failure of the
" manual loader", or failure of the E/I converter could also cause the manual control system to drive the ADVs to the 50% open position. This condition arises because the manual loader goes to zero-vol.ts output upon loss of input 24 volts or upon. internal failure.
Since a -10v to +10VDC control voltage was 'the selected range then zero volts is another midscale failure mode which resulted in opening the valves to the 50% position.
In the absence of reasonable testability of the E/I converter to detect such failures and the absence of any periodic surveillance activities being proposed, many of these failures 'are =
"undetectabl e".
Specifically our concern is that, upon loss of ICS power, the. -
control of the ADVs would be automatically transferred to-the proposed manual control channel which could then send the ADVs spuriously to the 50% open position due to an " undetectable" midscale failure.
Further, it is not evident that the operator will know how or be able to easily reclose the ADVs. -
To resolve our concern, the licensee has agreed to test the inanual backup channel every six months during p1' ant operation by transferring the control of the ADVs temporarily from the 'ICS to the new manual control channel to demonstrate that the channel will maintain the ADVs in the closed position. This matter will be included as part of the administrative controls pertainijig to this modification.
In addition, depending upon equipment delivery, the licensee expects to have both the proposed modification and administrative controls in place prior to restart.
Since the control power for ADVs and the position indicatar power are from opposite Divisions of the Class,1E power system, there is maximum assurance that both control and indication power will not be lost concurrently. Therefore, at this Unit, no modification is needed in this area.
Based on the above evaluation we concludethe licensee has' adequately responded te out request transmitted by letter dated August 15, 1980 and we therefore find the licensee's proposed modifications to the controls of the steam dump valves acceptable.
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Dated:
August 28,1981 4