ML17305B388

Summary of ACRS Advanced PWRs Subcommittee 900921 Meeting in Bethesda,Md to Discuss Feedback for ABB C-E Sys 80+ from Operational Experience at Plant

ML17305B388
Person / Time
Site:	Palo Verde
Issue date:	09/21/1990
From:	Advisory Committee on Reactor Safeguards
To:	Advisory Committee on Reactor Safeguards
References
ACRS-2722, NUDOCS 9103180386
Download: ML17305B388 (42)

Text

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ACCESSION NBR: 9103180386 DOC. DATE: 90/09/21 NOTARIZED:

NO FACIL:STN-50-528 Palo Verde Nuclear Station, Unit 1, Arizona Publi STN-50-529 Palo Verde Nuclear Station, Unit 2, Arizona Publi STN-50-530 Palo Verde Nuclear Station, Unit 3, Arizona Publi AUTH.NAME AUTHOR AFFILIATION ACRS Advisory Committee on Reactor Safeguards RECIP.NAME RECIPIENT AFFILIATION ACRS Advisory Committee on Reactor Safeguards DOCKET g

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SUBJECT:

Summary of ACRS Advanced PWRs Subcommittee 900921 meeting in Bethesda,MD to discuss feedback for ABB C-E Sys 80+ from operational experience at plant.

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gggs-4 742 ACRS MEETING MINUTES/

SUMMARY

OF THE ADVANCED PRESSURIZED WATER REACTORS SUBCOMMITTEE SEPTEMBER 21, 1990

BETHESDA, MARYLAND PURPOSE The purpose of this Subcommittee meeting was to discuss feedback for the ABB Combustion Engineering (CE) System 80+ from operational experience at CE plants, in particular Palo Verde.

The entire meeting was open to public attendance.

ATTENDEES ACRS J. Carroll, Chairman I. Catton, Member C. Wylie, Member E. Wilkins, Member C. Michelson, Member M. El-Zeftawy, Staff T. Rotella, Staff ABB-CE DUKE ENGINEERING AND SERVICES NRC J. Burns, RES R. Van Houten, SECY T. Wambach, NRR I. Yoshida, NRR OTHERS Stan Ritterbusch Ernie Kennedy Joe Lungo John Waters Bill Heilker Bill Fox Frank Snipes R.

S. Turk Charles Brinkman Mike Cross John F. Mullooly Chung Lee, NUS Lynn Connor, NRC Calendar Tim Stack, BWNT D. R. Noonan, Search Licensing E.

M. Burns, Westinghouse Robert E.

Sweeney, Bethesda Licensing Office Mark Stella, Volian Enterprises 9103180386 900921 PDR PDR ADOCK 05000528 oak

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Minutes/APWR Subcommittee (9/21/90)

Meetin'i hli hts A reements and Re uests 1.

Mr. Carroll, Subcommittee

Chairman, stated the purpose of the Subcommittee meeting and introduced the other ACRS members.

2 ~

Mr. T.

Wambach, CE System 80+ Project Manager/NRR, who was recently assigned to the

project, stated that a

draft Licensing Review Basi.'s (LRB) document and associated Commission Paper responding to the Staff Requirements Memorandum is in'ts final stages of staff concurrence.

The Subcommittee will receive copies of both when they bcome available.

The final LRB document will be issued in the Spring of 1991.

Mr.

Wambach also stated that SECY 90-065 calls for a staff 7

review completion date of mid-1993 to mid-1994 for the CE System 80+.

He qualified these dates saying that they were based on the traditional SRP type review.

However, the Commission could require additional

reviews, but review completion would be at least that far off.

Mr. Wambach also noted that the staff has gained some time in that 340 requests for additional information have been made and CE has responded to about two-thirds of those.

The 90-065 schedule is based on an application being placed before the staff at which time the clock starts.

Mr. Wambach said the staff has gotten a bit of a jump on that with CE application submittals dating back to 1987-88.

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Minutes/APWR Subcommittee (9/21/90) 3 ~

Mr. E. Kennedy, ABB-CE, summarized CE's perspective regarding the LRB.

He stated that it was somewhat less useful now and noted that its issuance should not it affect progress toward design certification.

He provided his views on the history of the LRB and its role subsequent to the promulgation of 10 CFR Part 52.

Mr. Kennedy has been encouraging the staff to review the System 80+ RESSAR for design certification and the LRB in parallel.

Mr. Kennedy presented an overview to the Subcommittee which included the following sources of design input for the System 80+.

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EPRI utility requirements document

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Operation of ABB/CE-designed plants

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ABB/CE corrective actions program

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Duke power

design, construction, and operation of seven plants

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other design input (NRC, INPO, etc.)

Mr. Kennedy pointed out that CE's presentation included System 80 (Palo Verde) operating experiences and the design considerations that will go into two units under construction in Korea (Yong Wang 3

and 4) which are expected to be completed in 1995 and 1996.

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Minutes/APWR Subcommittee (9/21/90)

In response to comments in the fire protection

area, Mr.

Kennedy requested a reference for the "Sizewell B" report from the staff.

Mr. Kennedy related to the subcommittee that CE is submitting an application for certification for the entire plant, except for site-specific issues, including the balance of plant.

CE is designing the NSSS and is sub-contracting with Duke Engineering and Services to provide the remainder of the plant systems design.

4.

Mr.,Waters, ABB-CE, briefed the Subcommittee on the System 80+

reactor coolant pump (RCP) design features and their comparison with the System 80 and YGN designs.

He began with a description of the RCP problems that occurred at Palo Verde Unit;-1 including the broken impeller vane segments and broken diffuser and suction pipe retaining bolts.

Some of the System 80+

RCP design features presented were:

SYSTEM 80+ IMPELLERS

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They have the same hydraulic configuration as Palo Verde

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The materials used and th'e mechanical design criteria will be the same as Palo Verde

& YGN

Minutes/APWR Subcommittee (9/21/90)

SYSTEM 80+ DIFFUSER SUCTION PIPE

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The design for the retaining diffuser

& suction pipes is same as Palo Verde

& YGN Cracks were found in the Palo Verde RCP shafts adjacent to the top of the keyway for the pump impellers.

Mr. Waters indicated that micro cracks in the chrome plating propagated into the base metal by cyclic fatigue.

Also, the sharp bottom corners in the keyways caused high stress concentrations in the shafts at that point.

CE reported the corrective actions in these areas included:

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Removing the chrome plating from the affected areas

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Extend the stop seal at the RCP shaft and hub area interface to prevent thermal shock

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Enlarging the radius in keyway bottom corners to

,reduce stress concentrations The System 80+ impeller to shaft connection willuse a spline-faced design.

Mr. Waters stated 'that all of the Palo Verde RCP shafts have been replaced.

In response to Subcommittee questions, he provided details on the RCP seals and their cooling design.

Mr. Waters explained that ABB-CE believes that the maximum expected RCP seal

Minutes/APWR Subcommittee (9/21/90) leakage is approximately 1 gpm during a loss of seal cooling (station blackout (SBO)) event.

To support this belief, he stated that the past operating history of the Palo Verde pumps have demonstrated the ABB-CE seal design works very well.

He reported that there have been no instances of unscheduled shutdowns of Palo Verde to replace the RCP seals.

He also stated that the SBO event issue has been addressed by testing conducted for the St.

Lucie Nuclear Plant.

ABB-CE uses a

C mechanical seal (as opposed to the W hydrostatic seal) which withstood 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> of no external service for seal cooling.

Mr. Waters also indicated that at Palo Verde, RCP seal cooling was lost for over 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> and there was no change in RCP seal leakage.

He stated, in fact, the RCPs were run for 20 minutes with no sealing cooling and subsequently perform acceptable for more than eight months until the next refueling outage.

5.

Mr.

R.

S.

Turk, ABB-CE, briefed the subcommittee on their operating experience with other issues including Resistance Temperature Detectors (RTDs)

Thermowells (TW),

Upper Guide Structures

'(UGS),

Heated Junction Thermocouples, and Safety Injection Nozzle Thermal Sleeves.

The Reactor Vessel Welds issue was saved for a later presentation.

The failure modes and the corrective action taken for the RTD TW's are given in CE's handout provided during the meeting.

The root cause of the failures apparently was attributed to

Minutes/APWR Subcommittee (9/21/90) high cycle vibration due to flow induced vortex shedding.

An improved RTD TW is now employed at Palo Verde and will be used in the System 80+.

Mr. Turk stated that high cycle fatigue failures were found in the CEA shroud packages and were due to normal RCP induced vibrations in the UGS.

As corrective actions, CE chose to; I

modify the UGS at Palo Verde to include removal of the top three inches of CEA shroud and CEA guides, incorporate a

separate guide structure support system, and add snubbers on the CEA shroud.,

Mr.

Turk briefed the Subcommittee on their operational experiences with heated junction thermocouples (HJT).

He stated that the HJT system is a

post-TMI system used to measure reactor vessel level during a small break LOCA. After describing their method of operation, Mr. Turk stated that the primary failure of these devices was an open circuit in the l

heater leads of the sensors.

CE could not determine the root cause of the lead failures.

However, CE replaced the material of the electrical lead with a higher strength material and there have been no subsequent failures.

This new material will be used in the System 80+ design or CE will use the latest developed design of that product.

Mr.

Turk briefed the Subcommittee on their operational

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Minutes/APWR Subcommittee (9/21/90) experiences with safety injection nozzle thermal liners at Palo Verde.

During hot functional testing at Palo Verde, the subject thermal liners became displaced on Loops 1-A and 1-B.

The cause of the displacement was determined to be flow-induced forces or vibration resulting in a rotation of the nozzle thermal liners and subsequent damage.

Mr. Turk stated that all of the nozzle thermal liners were removed from Palo Verde and repaired.

He explained further, that by analysis, the thermal liners were shown as not needed and

were, therefore, left off the Palo Verde plant.

The entire issue goes

away, however, for the System 80+ design because the nozzles no longer exist as part of the design.

For the System 80+, safety injection goes directly into the vessel.

Mr.

Turk stated that when ABB-CE completes the detailed nozzle

design, they will determine, at that time, whether to use a thermal liner.

6.

Mr. W. Heilker, ABB-CE, briefed the Subcommittee on the System 80+

System Generator's (SG) geometry and parameters.

He compared the SGs to the Palo Verde and YGNs SGs.

Many illustrations and cutaway drawings were provided in the CE presentation package handout.

A SG parameter comparison table was also provided and is included as Attachment I.

Although the System 80+ thermal rating is the same as Palo Verde's, the liquid inventory and number of SG tubes are increased for the

Minutes/APWR.

Subcommittee (9/21/90)

System 80+.

The System 80+

SG enhancements can be summarized as follows:

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Increased downcomer volume

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Improved tube integrity

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Lower Type

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Lower steam pressure

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Increased heat transfer area

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Improved access for maintenance

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Improved dryers

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Designs to avoid waterhammer, and a

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Higher recirculation ratio Mr. Heilker s presentation included a detailed discussion of certain SG issues including sludge management capabilities, an improved design to mitigate previously observed tube wear at the "batwing",tube supports and in the economizer/tube lane

corners, and SG tube vibration mitigation.

7.

Mr.

W.

Fox, Duke Engineering and

Services, briefed the Subcommittee on the System 80+ fire protection,

sabotage, security, and flood design considerations.

In the interest of addressing the Subcommittee's specific and

Minutes/APWR Subcommittee (9/21/90) 10 immediate interests, his presentation was abbreviated to include building layout with particular attention to fire protection design.

Mr. Fox stated the system 80+ design goal in the fire protection area is "defense in-depth" using a

reliable detection system and protection of redundant trains of equipment.

Three hour fire walls or barriers are provided between protection instrumentation channels and safety related divisions.

Where walls or barriers can not be provided, 20 foot separation with no intervening combustibles is used.

In response to the Subcommittee concerns regarding migration and effects of heat and smoke due to a fire, Mr. Fox described the Heating Ventilation and Air Conditioning (HVAC) System 80+ design as one which has separate supply systems, separate exhaust systems and internal room chillers.

Mr. Fox related to the Members that he had not seen the "Sizewell B" report which addresses room pressure buildup due to a fire.

A reference to the "Sizewell B" report was requested from the ACRS staff and subsequently provided to him.

Mr.

Fox offered a

general discussion of security issues including hardened walls, minimizing irregularly shaped structures in and out of the plant, and the use of detection and procedures.

Mr. Fox stated that the System 80+ design goal for internal

Minutes/APWR Subcommittee (9/21/90) flooding is to protect the vital as well as non-vital structures from flooding.

He stated that the criteria to meet this goal is redundancy of channels and divisions, separation of non-safety and safety related equipment and a separation, where

possible, of electrical and mechanical equipment throughout the plant.

Also, to help address the consequences of the potential flood from a pipe break or rupture, passive flood control is provided via curbs, raised floors, pedestals and drains.

Mr. Fox stated that for any kind of a credible release of water internal to a site structure, the reactor could be safely shut down.

In response to a Member question, regarding unwanted equipment actuation from the wetting of electrical equipment during Mr.

Fox's presentation, Mr. Turk responded saying the majority of the resolution to this issue would be provided during a

presentation of the advanced I&C systems being utilized in the System 80+ design.

Mr.

Fox concluded his presentation with an overview of the spherical containment layout and the annex which includes the reactor building, fuel pool, and main steam valve houses.

He pointed out structures around the site including the administrative building, security, storage facilities and the gas-turbine electrical generator.

The gas-turbine location was, however, pointed out as being site-specific with respect to its location;

but, where ever it ended up, its final

Minutes/APWR Subcommittee (9/21/90) 12 location would be analyzed with respect to other site equipment.

8.

As a result of the Subcommittee '

discussion, Subcommittee members expressed the following concerns.

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Mr. Michelson requested, updated copies of the System 80+

CESSAR DC Volumes 1 through 17 for his use at home.

Other members indicated that they need these updated copies also.

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, Mr. Carroll inquired about the CE System 80+ RCP seal injection function during a station blackout event in light of an expected future Generic Letter which would require demonstration of RCP seal survivability during such an event.

As previously stated, ABB-CE discussed Palo Verde's RCP past experience and their results of the SBO type testing on RCP seal performance.

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Dr. Catton questioned CE's design process with respect to lack of analyses for natural frequencies of components in flow streams and the use of an old design in a

new application without examining the frequencies expected to occur.

ABB-CE indicated that in this

instance, the lack of analyses-was an oversight during the design process.

Minutes/APWR Subcommittee (9/21/90) 13

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Mr. Carroll inquired about CE's experience with the Palo Verde loose parts monitoring (LPM) system since they had an opportunity to collect data as-a result of the broken parts in the Palo Verde RCP.

ABB-CE stated they would check into this but did not recall any LPM system data being available.

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Dr. Catton inquired about the design and functioning of the HJT probes.

He requested information from CE on these devices and a

future briefing on these devices.

Mr. Michelson shared this sentiment and requested staff input also.

Dr. Catton commented with regard to the Heated-Junction Thermocouples (HJT) saying that if you look at calculations of vessel level versus time, the level falls very fast through the region of the HJT because there is only a short "window" in which the device works very well.

He also pointed out that a Delta P calculation would give you vessel level continuously over the whole range of the vessel.

Mr. Michelson shared this sentiment.

ABB-CE stated that the operators would rely on the core exit thermocouples when vessel level dropped beyond the operating region of the HJT.

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Mr. Carroll commented that a thermal sleeve on the System 80+ safety injection connection to the vessel

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Minutes/APWR Subcommittee (9/21/90) 14 should probably be required because of the potential for small amounts of cold water in leakage and the resulting potential for thermal fatigue cracking of the vessel on nozzle.

ABB-CE stated that the System 80+ design would probably include thermal sleeves.

However the detailed nozzle design is not yet complete.

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Mr. Carroll stated that since Dr.

Shewmon was unable to attend this Subcommittee meeting, CE would have to postpone their presentation of the System 80+ reactor vessel design until the next meeting.

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Mr. Carroll expressed concern with regard to feedwater (FW) distribution in the SGs.

He stated that a water hammer might occur if steam was formed in the FW sprayer from an interruption of feedwater and a

subsequent addition of cold water were to occur.

ABB-l CE stated that the "box" area is ventilated in that it is segmented allowing flow at the top of either end of the segments.

The water coming down through the economizer region is subcooled the entire length of the economizer.

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Dr. Catton requested information from CE with regard to the ATHOS and FLOW-III computer codes referred to during the presentation of SG tube vibration studies.

Minutes/APWR Subcommittee (9/21/90) 15 ABB-CE committed to get this information.

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Mr. Michelson pointed out that the NRC staff has previously and is currently rejecting using physical space (20 feet separation with no intervening combustibles) alone as a fire protection barrier.

He suggested that Duke Engineering look into this subject.

Mr. Carroll shared the same sentiment.

Mr.

Snipes, Duke Engineering, stated that separation is only used when barriers are not possible.

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Mr. Michelson inquired if Duke Engineering s current plans include a fire sprinkling analysis for safety related multiplexing transmitters which would consider unwanted actions as well as a total loss of equipment function.

ABB-CE stated that when they come to ACRS to talk about the System 80+ Nuplex 80 Advanced I C System, they will'ddress this issue.

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Mr. Wylie commented that the site layout drawings indicated that the location of the gas-turbine f

generator is a

considerable distance from the essential switchgear to which it supplies power to.

He also inquired as to whether a short-circuit voltage drop analysis had been performed.

ABB-CE could not answer this question.

However, it was stated that the location of the gas turbine is a site-specific issue.

Minutes/APWR Subcommittee (9/21/90) 16

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Mr. Michelson pointed out that he thought the System 80+ plant was a standard design and would be the same for each licensee except for the intake structure.

He stated that if things started to be relocated from site to site (e.g.

the gas-turbine) many things including analyses must be changed and you no longer have standard plants.

ABB-CE stated that the degree to which equipment and buildings can be moved for a given site (in light of the standard design concept) is yet to be definitively defined.

Each change would have to be analyzed for distance, orientation and so forth.

Mr. Michelson further commented that the site layout looked good and well thought out at first look.

FUTURE ACTION As a result of the Subcommittee Members concerns, discussions, and issues not yet discussed (fire protection issues, the Nuplex 80 advanced I

& C system, HJT's, and Reactor Vessel Welds) a new list of items will be prepared by CE and the ACRS staff for future Subcommittee considerations.

The CE presentation on the System 80+

reactor vessel design will be made during the next Subcommittee meeting.

CE has committed to transmit the material requested during the meeting to the ACRS staff.

Minutes/APWR Subcommittee (9/21/90) 17 The reference for the "Sizewell B" report on Fire Protection has been provided to CE by the ACRS staff.

The Subcommittee Chairman plans to provide a Subcommittee Report to the full Committee during the October 1990 meeting.

NOTE 0 Additional'eeting details can be obtained from a

transcript of this meeting available in the NRC Public Document Room, 2120 L Street, NW, Washington, DC 20006/

(202) 634-3273, or can be purchased from Ann Riley and Associatesg Ltd g

1612 K

Street, NW, Suite 300@

Washington, DC

20006, (202) 293-3950.

Documents Used 2.

ABB-CE System 80+

CESSAR DC The slide presentation package used by CE during the meeting is available from the ACRS staff.

STEAM GENERATOR PARAMETERS PLANT THERMAL RATING, MWT

'TEAM PRESSURE AT 100~a POWER, P)IA PRIMARY FLOW RATE)

LBM/HR X 10 HOT LEG TEMPERATURE, F

'COLD LEG TEMPERATURE)

F FEEDWATER TEMPERATURE)

F LIQUID INVENTORY) LBM BOIL DRY TIME, MIN.

NORMAL LEVEL LOW LEVEL TUBE MATERIAL NUMBER OF TUBES AVG. TlJBE LENGTH, FT HEAT TRANSFER AREA, FT TUBE SUPPORT GRIDS LONGEST TUBE SPAN, IN.

TUBESHEET THICKNESS, IN.

DRY WEIGHT, TONS.

PALO VERDg 380 1070 82.0 621 564.5 450 92, 185 40 22 I600 11,012 57.7 124,800 6F+2P 43.25 23.5 743 YGN

~54 2825 1070 60.8 621 564.5 450 85,710 44 24 j600 8,214 63.6 102,500 8F+3P 39.72 21.5 597 3817

'000 82.0 615 557 450 115,000 54 31 I690Tl'2,300 60.6 146,450 8F+3P 36.0 27.0 850 SYSTEM Q>004

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.<IBUTION ocket File PDV r/f Septerrtber 21, 1990 DFoster DOCKET NO(S).50<<528'0-529 and 50-530 To attached addresses The-following documents concerning our review of the'subject facility are. transmitted for your information.

t DESCRIPTION OF DOCUMENT DATED Notice of Receipt of Application Draft/Final Environmental Statement Notice of Availabilityof Draft/Final Environniental Statement Safety Evaluation Report, or Supplement No.

Environmental Assessment and Finding of No Significant Impact Notice of Issuance of Environmental Assessment Notice of Consideration of Issuance of Facility Operating License or Amendment to Facility'Operating License, Biweekly Notice; Applications and Amendments to Operating Licenses S

p

'.Involvin No Si nifIcant Hazards Conditions See Page(s>

Exemption Construction Permit No.,CPPR-

, Amendment-No."

Facility Operating License No.

,Amendment No.

Order Monthly Operating Report for transmitted by Letter

, Annual/Semi-Annual RePort: Ra@Loec~

2/01/89 transmitted by Letter.

, /30/90 Other Office of Nuclear Reactor Regulation Doris J. Foster, Licensing Asst.

jgxpIcrm Prospect Directorate V Dikision of Reactor Prospects

III, IV, V and Special Prospects

Enclosures:

As Stated CC:

See next a e

.M,'FDV............

DFoster:df 9/21/90 OFFICE>

SURNAME>

OATEN OFFICIAL RECORD COPY NRC FORM 31a t10/aOI NRCM 0240

SUBJECT:

Arizona Public Service Co., Palo Verde Nuclear Station, Units ls 2 and 3

I a

ADDRESSES:

Chief Division Ecological Services Bureau of Sport Fisher ies and Wildlife U.S. Department of the Interior Washington, D.C.

20240 Dr. William Cunningham FDA Research Chemist National Institute of Standards 5 Technology Reactor Building 235, Room B108 Gaithersburg, Maryland 20899 U.S. Environmental Protection Agency Region X Office.

Attention:

Regional Radiation Representative 1200 6th Avenue

Seattle, Washington 98101

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