ML20238E008

Responds to 870715 Questions Re Plant Concerning GE Pumps

ML20238E008
Person / Time
Site:	Pilgrim, Maine Yankee, 05000000
Issue date:	09/01/1987
From:	Abraham K NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I)
To:	Strout B AFFILIATION NOT ASSIGNED
Shared Package
ML20238E010	List: ML20238E008 ML20238E016 ML20238E026 ML20238E034
References
IEIN-86-039, IEIN-86-39, NUDOCS 8709140051
Download: ML20238E008 (8)

Text

'

sus UNITED $TATEa

) .,

8 NUCLEAR REGULATORY COMMISSION e

• $ REOl0N I

'I

, e31 PARK AVENUE KINO OF PnUSSIA, PENNSYLVANIA 194e6 a...*

Barbara Graves Strout 5 trout Road Poland Spring, Maine 04274 1

Dear Ms. Strout:

Thank you for your July 15, 1987 letter (a follow-up set of questions to my 1 May 28 response to your earlier inquiries).

1 It has taken us a while to respond because of the number and technical  ;

specificity of your questions. We will restate each of your questions and j then give our response, which we hope will clarify these matters for you. j

1. Did the Nuclear Regulatory Commission notify officials at Maine Yankee l Atomic Power Plant to check whether or not they have G.E. pumps?

Specifically did the NRC notify John Arnold? Did the NRC notify Charles i Frizzle, manager of operations at Maine Yankee Atomic Power Co.? I

/

Maine Yankee was informed in Inspection and Enforcement (IE) l Information Notice No. 86-39, dated May 20, 1986, that problems existed with certain General Electric vertical induction motors based on damage to this pump at the Peach Bottom facility. The ,

damage described in this Notice was wear ring failure in the l Bingham-Willamette pump which was attached to the GE motor. _ The NRC sends out Information Notices to inform the industry of potential problems. The industry also has other mechanisms available to share j information concerning identified problems. Specific responses to 1 Information Notices are not required. Our records indicate that neither Mr. Charles Frizzle nor John Arnold were specifically addressed a copy of Information Notice 86-39; however, by sending Information Notices to all licensee's the ERC considers each licensee to have been informed.

2. I am requesting that if the above answer is in the affirmative, then the NRC request an answer from John Arnold and Charles Frizzle as to (yes)

Maine Yankee does have G.E. purrps or (no) it does not have G.E. pumps, and if Maine Yankee does have G.E. pumps, are they damaged?

Our inspections have determined that Maine Yankee does not have this type of pump or motor in use.

3. In light of all of the information included within the above listed newspaper articles are the people of Maine and New England being given the whole truth about the turbine problem at Maine Yankee?

8709140051 870901 R ADOCK OS0 g 9

i 2

The NRC does not comment on information printed in magazines or newspapers, nor do.we review those articles for accuracy unless. the author requests it prior to publication, and that is a very rare occurrence. - The NRC, however, is concerned about problems in the ]

secondary side of .the plant that may contribute to postulated acci- 4 1

dent scenarios at' any plant. In essence, the nuclear plant produces steam. How that energy in that steam is converted into electric power-is the. licensee's' business. The NRC ensures that the impact of the secondary system on the reactor system operation is minimized._ For example, when the turbine trips from a power level above 15 perc;ent, i an automatic reactor trip occurs. The NRC would be concerned if.

repeated problems with the secondary systems cause repeated ups and l downs of the reactor systems because each trip challenges the reactor protection system. However, in this case, our reviews indicate that the licensee appears to be taking prudent action- to i resolve the vibration problems of the main' turbine' prior to placing the turbine back into continuous service. Even though this down. time is an expense for the utility in terns of replacement power, the NRC is of the opinion that resolving secondary plant problems prior to challenging automatic safety systems is sound operating philosophy,

4. Is the turbine problem at Maine Yankee the result of design flaws $1m11ar to those that the NRC is said to have joined General Electric Co. in keeping secret? l

.The simple answer to your question is no. Turbine vibration problems have been known at many electric generating plants, nuclear and fossil, built by manufacturers. The turbine generator at Maine Yankee exhibits vibrations when the riain turbine is running. After each outage vibration readings have been taken on the main turbine to determine the balance condition of the turbine. It is not unusual for the' licensee to add or subtract weights to the turbine in a mennes similar to balancing an automobile tire. The repair of a balance problem requires running the turbine to measure the vibra-

, tions. In order to run the turbine, the rearctor must be placed in service, main steam lines warmed, and associated secondary systems placed in operation. Once the balance weight is calculated the turbine must be stopped and the weights added. Sometimes this evolution requires shutting down the secondary side of the plant to gain access to the turbine. When this balancing effort did not resolve the latest vibration problems, the licensee searched for other clues. An analysis of vibration measurements indicated a rub in the turbine was the probable cause and the licensee initiated a program to find the components which were rthbing against each other. .

This program had three phases with the most accessible components being the first to be checked. When checks of the most accessible equipment did not uncover the source of the rubbing, the licensee continued to implement successive phases of its plan. The licensee has now entered the third phase of their investigation which requires disassembly of the low pressure turbines so as to continue the search of the rubbing components. Other information gained during the

3 testing of the turbine is being analyzed to identify the possible cause of the vibration problem. NRC inspectors are onsite following licensee action as it may affect future safe operation,of the plant, but they are not involved with the specifics of the turbine repair l effort.

5. These design flaws that cost utilities and their customers millions of dollars to fix. Is there any information (pro or con) on Westinghouse Electric Corp's turbine generator designs, in rel.ation to Nuclear Power Plants? J Westinghouse is one manufacturer of turbine generators. During the initial design of the plant the licensee determined what type of turbine generator he would use. The NRC is aware that turbine generators contribute to plant availability, however, the NRC does not have regulatory authority over non-nuclear safety systems and ,

therefore, does not keep records of reliability of various brands )

of turbine generators.

6. Can the NRC assure Maine and New England residents that starting and

. stopping this Atemic Plant and having to operate the plant at much lower

- than capacity in order to safeguard the repairs done to the turbines is safe?

Maine Yankee was operated in accordance with their Technical Spect- ' . ,

fications and operating procedures during the time the turbine was being tested. Our onsite Resident inspector witnessed a variety of tests pertaining to the operation of the plant during that timeframe.

The derating of the unit is a result of the repairs made to a low pressure turbine during the most recent cutage. During a refueling outage, a low pressure turbine is disassembled and inspected. The purpose of this inspection is to identify any deterioration of the turbines. In years past this type of inspection has identified turbine disc cracking at the keyway used to secure the blade to the disc, and blade root cracking. Corrective actions have included ,

redesign of the disc to eliminate the keyway and a different design of blade attachment to the discs. When cracks were identified in one of the low pressure turbines in the vicinity of the blade and disc attachment, an expanded program of inspections was conducted at Maine Yankee. The second low pressure turbine was disassembled and inspected for these cracks as well as the spare low pressure turbine.

Of these three turbines, one was found free of cracks. The licensee determined that the best course of action was to reuse the one good turbine and cut the cracked blading from one of the remaining low pressure turbines.

Once this blading was removed, baffles were installed within the low

. pressure turbine in order to assure that the steam flow remained balanced in the machine. The installation of the baffles resulted in the derating of the turbine. The reactor plant remains rated at full capacity. It is not uncommon to spply operational limitations on the f -

i ,

4 a

main turbine. A number of conditions could affect the main turbine, from complex high steam flow / erosion of blade tips, to the number and capacity of feedwater pumps in operation. Some of thetse limitations may be caused by. other plant conditions. In this case the derating of the main turbine is a function of the condition of the internal components in the low pressure turbine.

7. Could vibrations in the turbine units cause the feedwater system to leak?

or fail? at Maine Yankeer It is unlikely that the feedwater system would be af fected by vibra-( tions in the main turbine for several reasons. The turbine rests on

~

a rigidly constructed floor within the turbine building. The vibra-tions experienced in the main turbine are relatively small, causing movements of 10 to 18 mils. (One mil of vibration is 1/1000 of an inch. While this small amount of vibration could lead to premature failu)e r of the turbine, the feedwater system is designed to flex and i expand as operating temperatures increase. The feedwater piping is I supported by shock absorbers in a manner that allows pipe movement under varying conditions. Additionally, the feedwater system has been designed to accommodate such movement, a

, 8. Are the two safety systems, the ones Maine Yankee was fined $80,000 January 26 of 1986 for having inoperable for more than one year the ones that would close the plant down when the feedwater system becomes inoperable, and.the one that would shut the plant down when there is low steam pressure on the secondary side of the steam generators are they working?

The two safety systems, low steam generator (S/G) pressure trip (a trip is an automatic precautionary shutting down of a system on a

"' sensing of an abnormal condition, in this tastance, low pressure) and the feedwater trip systems are operational at Maine Yankee. Operability of these systems is required by the plant's Technical Specifications during certain operating conditions. These two systems provide for a special set of potential conditions at Maine Yankee. The NRC requires each licensee to analyze its plant under various accident conditions. One of these accident conditions is called a Steam Line Break Accident. If a pipe carrying steam were to break, the resul-tant cooling down of the reactor system and the release of the steam energy into containment could lead to premature failure of the containment system and ultimately the release of radioactive fission products to the atmosphere. In order to protect against such an accident, the licensee must show that if this accident were to occur,

,/ the plant would automatically function to eliminate the possibility  !

/ of this overpressurization of the containment building. The low $/G i pressure trip function is designed to sense a low pressure condition that would exist during a $ team Line Break Accident and shutdown the i plant. Additionally, the feedwater trip system receives an input i g from the low S/G pressure and isolates the feedwater to that $/G. '

('

o 5

V This is important because adding additional water to a faulted $/G with a break inside of containment would only cause the pressure inside of containment to rise in excess of the design 5ressure of the containment building.

The Civil Penalty that was imposed upon Maine Yankee was for not ,

having the required number of low pressure detectors available during an operating condition when they were required to have them and hailing one channel of the feedwater trip system inoperable for a different reason. Details of these events are described in NRC Inspection Reports 85-19 and 85-27 which are available in the Wiscasset Library, where the NRC has put the public document room for '

Maine Yankee.

One question that you asked in the beginning of your letter was how could 37 inspections conducted in 1985 fail to identify an inoperable system for over a year. The NRC Resident Inspection Program assigns one or two residents at each site. Although these inspectors make daily tours and system walkdowns through-out the plant, they do not operate equipment. That is the sole responsibility  ;

~~

of the utility. If operation of valves or equipment by just anyone was '

permitted, then operability of essential equipment could not be ensured. Of the 37 inspections conducted during that year, two inspections focused on the events surrounding the discovery of two inoperable systems but they were con-ducted after the licensee discovered the condition. The discovery of the shut root valves was.only made after those valves were repositioned. The discovery of the problem with the remaining channel of low pressure protection was made during the conduct of an NRC required surveillance to check the setpoints of the trip system. In each case, it is not feasible that an NRC inspector would have identified the condition. The NRC requires each licensee to report deficient conditions to the NRC in accordance with strict guidelines, j The low )ressure valves that were found closed were only identified after troubles 1ooting deficiencies.in pressure indication. In fact, even though f i

the valves were discovered closed, there was enough leakage past the the '

valves to provide normal indication of pressure to the control room operators.

During the Enforcement Conference between the NRC and the licensee it was determined that sufficient redundancy existed in the Reactor Protective System to provide for a plant trip during the steam line break accident scenario without the low pressure detectors in service. The NRC acknowledged the redundancy but did not credit the plant for the redundant systems since they were required to have the luw pressure detectors operable. The feedwater trip system war also a subject of that Enforcement Conference. The feedwater trip system receives some of its information from the low pressure detectors. Since the detectors were considered inoperable, the feedwater trip system was also inoperable. The licensee showed that the affect of not isolating feedwater .

during a steam line bred accident was no worse than what the NRC had approved l for other plants. The LM did not accept this argument since Maine Yankee was l not licensed to this different criteria. Therefore, although the licensee showed that in each case there were redundant systems available and that the the overall affect of a steam line break accident was within acceptable limits,  !

the NRC still imposed a $80,000 Civil Penalty since the plant did not meet the '

I i

_ ,_,.-____ _,,___-___-,a- , , - - - - _ _

t ,

6 a

requirement in its license. ' All oilhese ana' lyses did not take credit for operators, who could have used other instrumentation arid equipment controls to mitigate the effects of a steam line break. .

I believe that covers all the points you raised. Please contact me again if we can be of further assistance.

Sincerely, M

, Karl Abraham Sr. Public Affairs Officer NRC Region I Office of Governmental and Public Affairs CCI The Honorable George J. Mitchell, United States Senate The Honorable William S. Cohen, United States Senate The Honorable Olympia J. Snowe, United States House of Representatives

. The Honorable Joseph Brennan, United States House of Representatives The Honorable William R. Sharp, United States House of Representatives

, Chairman, Subcommittee on Energy and Power The Honorable John R. McKernan, Jr., Governor of Maine The Honorable James Tierney, Attorney General, State of Maine C. E. Monty, President C. D. Frizzle, Assistant Vice President / Manager of Operations J. H. Carrity, Plant Manager P. L. Anderson, Project Manager G. D. Whittier, Licensing Section Head l J. A. Ritsher, Attorney (Ropes and Gray) '

Phillip Ahrens, Esquire Public Document Room (PDR)

Local Public Document Room (LPDR)

Nuclear Safety Information Center (NSIC)

NRC Resident Inspector State of Maine I

l l

em. ...

Y,7 l o b

.7) ', ,.,!,i *

.} ,,i- <;

k'?

UNITED STATES - - ' -

'e i..

,' o, NUCLEAR REGULATORY COMMISSION ;  ;- ,

1

- M WASHINGTON, D. C. 20555 '

el

[ ' .k

. m jj

-e+,

'lo EDO. PRINCIPAL. CORRESPONDENCE CONTROL -i

.i g --__ __________ ______________________

DUE: 08/IS/87f EDO CONTROL: :.;003073 :

l i NB' "OM:- '

DOC DT: :07/27/97"

REP. PHILIP R.: SHARP

, > FINAL ' REPLY::

r y

ETO:-

o i; c ,

CAAIRMAN-

.o

FOR ' SIGNATllREI OF:-- ** GREEN *F. SFCY NO: 87-0934  ;

TRUSSELL; iDESC: ROUTING: a CNCI. LETTER FM BARBARA' GRAVES STROUT'RE MURLEY. NRR.

'4 NLGRIM'AND MAINE YANKEE _ _

---i ,  ;

LhM:,08/C4/87.

'l

ASSIGNED TO: RI CONTACT: RUSSELL iSPECI AL ' INSTRUCTIONS OR RFMARKS: .q

<i s ., '

REPL . DIRECT.TO CONST3TUENT WITH CC TO' REP. SHARP l r i i

l 1

1 1

1 I,

a I \

1 _.

us c=1_z_1 _ __.1_. __._ ___..:._________________________. _ _ _ _ _ . . _ _ _ _ .__ __ _ _ _ _ . _ _ _ _ _ _ . _ _ _ _ . _ _ _ _ _ . _ _ _ _ _ _ . . _ _ . _ _ _ . . _ _ . _ . . . _ _ _ . _ . . _ _ _ _ _ _

~

~

, s p

u. .

O.,A Q '- -

q

.t- 1 OFFICE OF THE SECRETARY i CORRESPONDENCE CONTROL TICKET l 1 PAPER NUMBER: ' CRC-87-0934 LOGGING DATE:Jul'31 87 .

s

' ACTION OFFICE: EDO' L'.. AUTHOR: P.R. Sharp--Const Ref j '

. AFFILIATION: .-U.S. HOUSE OF REPRESENTATIVES 1 LETTER DATE:~ Jul 27 87 FILE CODE:

SUBJECT:

. Problems with. General Electric pumps--ref Pilgrim .l and Maine. Yankee. plants j ACTION: Direct Reply DISTRIBUTION:. OCA to Ack )!

SPECIAL HANDLING: None NOTES: Barbara Graves Strout 4 1

DATE DUE:- Aug 14 87 SIGNATURE: .. 'DATE SIGNED:

' AFFILIATION:

l l

l

- 003073 300 l.

f Rerd Off. E00 Date _..

Il'Y'I7 _

Time ik. __