NUREG-1044, Raises Concerns Re Auxiliary Pressurizer Spray Sys,(Aps) & Supporting Sys Due to Heavy Reliance on Reliability of APS in NUREG-1044.Need for safety-grade APS Should Be Addressed

Raises Concerns Re Auxiliary Pressurizer Spray Sys,(Aps) & Supporting Sys Due to Heavy Reliance on Reliability of APS in NUREG-1044.Need for safety-grade APS Should Be Addressed

ML20138M780
Person / Time
Site:	05000470
Issue date:	10/29/1985
From:	Thompson H Office of Nuclear Reactor Regulation
To:	Scherer A ABB COMBUSTION ENGINEERING NUCLEAR FUEL (FORMERLY
References
RTR-NUREG-1044 NUDOCS 8511040400
Download: ML20138M780 (5)

Text

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p WASHINGTON, D. C. 20555 74 October 29, 1985 Docket No.: STN 50-470 Fr. A. E. Scherer, Director Nuclear Licensing Combustion Engineering, Inc.

1000 Prospect Hill Road Windsor, Connecticut 06095

SUBJECT:

AUXILIARY PRESSURIZER SPRAY SYSTEM FOR CESSAR-F

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On September 12, 1985, Arizona Nuclear Power Project (ANPP) conducted a plant incorporating a Combustion Engineering (CE)g Station Unit 1, the first loss-of-load test on Palo Verde Nuclear Generatin CESSAR-F nuclear steam supply system to become operational, from approximately 65% power. The plant did not perform as expected. The test resulted in an event involving loss of all offsite power to non-essential loads (including the reactor coolant pumps), turbine trip and reactor trip. During the recovery phase of the event, overcooling of the reactor coolant system (RCS) occurred to the extent that the emergency core cooling systems were automatically initiated, followed by the associated automatic initiation of containment i sol a tior..

The following two sequences occurred during the event that caused the loss of all three charging pumps:

(1) When the safety injection actuation signal (SIAS) occurred, power to certain suction valves for the charging pumps was lost since the motor control center for these valves was classified as non-essential and, accordingly was designed to be automatically shed from the safety related electric buses.

(2) Because of a malfunction of the single water level instrument channel for the volume control tank (VCT), automatic control action was lost which would have transferred the suction of the charging pumps from the VCT to other water sources. Also, after the containment isolation signal was received, all makeup flow to VCT was isolated.

Due to the above sequences, the VCT emptied, the charging pumps became bound on t

i VCT hydrogen cover gas and the pumps were tripped.

This produced a potentially hazardous situation when, to re-establish charging pump flow, the lines from the pumps were vented to remove gas.

8511040400 851029 PDR NUREG 1044 C PDR

Mr. Scherer Subsequent to the above event, we met with representatives nf ANPP and CE on September 20 and October 8, 1985.

In these two meetings, ANPP and CE provided indepth design information about the auxiliary pressurizer spray system (APS) and its supporting systems. As a result of these meetings, we became aware of a possible misunderstanding of the scope of the APS during our review of the CESSAP-80 design.

We are concerned about the APS system and its supporting systems for the following reasons:

(1) The natural circulation cooldown analysis submitted for CESSAP-F relies upon the APS and its supporting systems for reactor coolant system (RCS) depressurization during cooldown; (2) The APS and its supporting systems are relied upon in mitigating the d

steam generator tube rupture (SGTR) accident and possibly other accidents requiring depressurization of the RCS when the main pressurizer spray is not available; ard (3) We relied heavily on the reliability of the APS and its supporting systems in our evaluation of the need for rapid depressurization i

capability for CE plants in NUPEG-1044, " Evaluation of the Need for a Papid Depressurization Capability for Combustion Engineering Plants."

As ycu know, we have a pending request from CE for an FDA amendment that is intended to close out confimatory issues related to the SGTR and natural circulation cooldown events.

In view of the above, we need additional infomation in order to complete our evaluation of that request.

Specifically, we request that you:

(1) Address need for a safety-grade APS and supporting systems (i.e., from its water source through the spray nozzles) considering the systems' functions as discussed above; and (2) Propose any changes in the CESSAR-F design and/or interface requirements as a result of the above.

Your response is needed before we can take any further action on your pending request for an FDA amendment.

Sincerely, fd Pugh L. Thompson, Jr., Director Division of Licensing Office of Nuclear Peactor Regulation

Enclosure:

As stated cc: See next page

so N M October 29, 1985 1

l Mr. Scherer Subsequent to the above event, we met with representatives of ANPP and CE on September 20 and October 8, 1985.

In these two meetings, ANPP and CE i

provided indepth design information about the auxiliary pressurizer spray l

system (APS) and its supporting systems. As a result cf these meetings, we became aware of a possible misunderstanding of the scope of the APS during i

our review of the CESSAR-60 design.

We are concerned about the APS systen and its supporting systems for the following reasons:

(1) The natural circulation cooldown analysis submitted for CESSAR-F relies upon the APS and its supporting systems for reactor coolant system (RCS) depressurization during cooldown; (2) The APS and its supporting systems are relied upon in nitigating the steam generator _ tube rupture (SGTR) accident and possibly other accidents requiring depressurization of the RCS when the main pressurizer spray is not available; and (3) We relied heavily on the reliability of the APS and its supporting systems in our evaluation of the need for rapid depressurization capability for CE plants in NUREG-1044, " Evaluation of the Need for a j

Papid Depressurization Capability for Combustion Engineering Plants."

As you know, we have a pending request from CE for an FDA amendment that is intended to close out confirmatory issues related to the SGTR and natural circulation cooldown events.

In view of the above, we need additional information in order to complete our evaluation of that reovest.

)

Specifically, we request that you:

(1) Address need for a safety-grade APS and supporting systems (i.e., from its water source through the spray nozzles) considering the systems' functions as discussed above; and (2) Propose any changes in the CESSAR-F design and/or interface l

requirerrents as a result of the above.

i Your response is needed before we can take any further action on your pending request for an FDA amendment.

l l

Sir erely, lib ugh L.

ompson, Jr., Director Divisic7 of Licensing Office of Nuclear Reactor Regulation

Enclosure:

As stated cc:

See next page DISTRIBUTION:

' Docket:Filez PDR NSIC SSP 8/ Reading HThompson CPatiel " ~

CThomas BSheron DCrutchfield

• SEE PREVIOUS CONCURRENCE SHEET Dp# D.

DL:SSPB*

CL:SSPB*

DSI:RSB*

D CPatel:ac CThomas BSheron DC1 hfie'd H ho.pson 10/21/85 10/21/85 10/22/85 10 85 10/j /85

t f

Mr. Scherer provided indepth design information about the auxiliary pressurizer spray i

system (APS) and its supporting systems.

As a result of these meetings, we became aware of a possible misunderstanding of the scope of the APS during our review of the CESSAR-80 design.

We are concerned about the APS system and its supporting systems for the following reasons:

(1) The natural circulation cooldown analysis submitted for CESSAR-F relies upon the APS and its supporting systems for reactor coolant system (RCS) depressurization during cooldown; (2) The APS and its supporting systems are relied upon in mitigating the steam generator tube rupture (SGTR) accident and possibly other accidents requiring depressurization of the RCS when the main pressurizer spray is not available; and (3) We relied heavily on the reliability of the APS and its supporting systems in our evaluation of the need for rapid depressurization capability for CE plants in NUREG-1044, " Evaluation of the Need for a Rapid Depressurization Capability for Combustion Engineering Plants."

As you know, we have a pending request from CE for an FDA amendment that is intended to close out confirmatory issues related to the SGTR and natural circulation cooldown events.

In view of the above, we need additional information in order to complete our evaluation of that request.

Specifically, we request that you:

(1) Address need for a safety-grade APS and supporting systems (i.e., from its water source through the spray nozzles) considering the systems' functions as discussed above; and (2) Propose any changes in the CESSAR-F design and/or interface requirements as a result of the above.

Your response is needed before we can take any further action on your pending request for an FDA amendment.

Sincerely, i

i Hugh L. Thompson, Jr., Director Division of Licensing Office of Nuclear Reactor Regulation

Enclosure:

l As stated cc: See next page DISTRIBUTION:

Docket File PDR NSIC SSPB/ Reading CPatel CThomas BSheron Crutchfield HThompson gp DL:SSPB B

DL:AD/SA DL:DIR l

CPatel:ac n

DCrutchfield HThompson I

10/,n /85 10g//85 10/2,7485 10/ /85 10/ /85

Docket No. STN 50-470 Coabustion Engineering, Inc.

(CESSAR) cc: Mr. G. Davis, Manager Standard Plant Licensing 1000 Prospect Hill Road Windsor, Connecticut 0E095 Mr. C. B. Brinkman, Manager Washirgten Nuclear Operations Combustion Engineering, Inc.

7910 Woodmont Avenue Bethesda, Maryland 20014 Mr. E. E. Van Brunt, Jr.

Vice President - Construction Projects Arizona Public Service Company

_;F=

P. O. Box 21666

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Phoenix, Arizona 85035 Ms. Patricia Lee Hourihan 6413 S. 26th Street Phoenix, Arizona 85040 Mr. Daniel F. Giessing Division of Nuclear Regulation and Safety Office of Converter Reactor Deploynent, NE-12 Office of Nuciear Energy Washington, D.C.

20545 Mr. Douglas Coleman Licensing Project Manager Washington Public Power Supply System P. O. Box 1223 Elma, Washington 98541 m__.

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