ML20012C090

Forwards Request for Addl Info Re Application for Certification of Advanced BWR Design

ML20012C090
Person / Time
Site:	05000605
Issue date:	03/14/1990
From:	Scaletti D Office of Nuclear Reactor Regulation
To:	Marriott P GENERAL ELECTRIC CO.
References
NUDOCS 9003200064
Download: ML20012C090 (6)

Text

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e Docket No. STN 50-605 March 14,1990 Patrick W. Marriott, Manager Licensing & Consulting Services GE Nuclear Energy General Electric Company 175 Curtner Avenue San Jose, California 95125

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION REGARDING THE GENERAL ELECTRIC COMPANY APPLICATION FOR CERTIFICATION OF THE ABWR DESIGN During the course of the review of your application for certification of your Advanced Boiling Water Reactor Design, we have identified a need for additional information.

Our request for additional information, contained in the enclosure, addresses the areas of SRP Section 7 reviewed by the Instrumentation and Control Systems Branch, and SRP Section 10.4, reviewed by the Materials and Chemical Engineering Branch.

We request that you provide your responses to this request by April 15, 1990.

If you have any concerns regarding this request please call me on (301) 492-1104.

Sincerely, disoC. Scaletti, Project Manager Standardization and Life 1

Extension Project Directorate Division of Reactor Projects - III, IV, V and Special Projects Office of Nuclear Reactor Regulation

Enclosure:

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Docket No. STN 50-605 l

Patrick W. Marriott, Manager Licensing & Consulting Services GE Nuclear Energy General Electric Company 175 Curtner Avenue San Jose, California 95125

SUBJECT:

REQUEST FOR ADDITIONAL INFORMATION REGARDING THE GENERAL ELECTRIC COMPANY APPLICATION FOR CERTIFICATION OF THE ABWR DESIGN J

During the course of the review of your application for certification of your Advanced Boiling Water Reactor Design, we have identified a need for additional information.

Our request for additional information, contained in the enclosure, addresses the areas of SRP Section~7 reviewed by the Instrumentation and Control Systems Branch, and SRP Section 10.4 reviewed by the Materials and Chemical Engineering Branch.

We request that you provide your responses to this request by April 15, 1990.

If you have any concerns:regarding this request please call me on (301) 492-1104.

Sincerely, 0.

Dino C.

Scaletti, Project Manager Standardization and Life Extension Project Directorate Division of Reactor Projects - III, IV, V and Special Projects Office of Nuclear Reactor Regulation

Enclosure:

As stated

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I ENCLOSURE REQUEST FOR ADDITIONAL INFORMATION MATERIALS AND CHEMICAL ENGINEERING BRANCH REVIEW 281.15 In a letter from Thomas E. Murley, NRR, to Ricardo

Artigas, G.E.,

Dated August 7, 1987, the staff provided the ABWR licensing review bases as well as the scope and content of the ABWR Standard Safety Analysis Report (SSAR).

In Section 8.7, Water Chemistry Guidelines, of the referenced letter, it states that GE has committed to using BWR Owners Group water chemistry guidelines.

These guidelines are necessary to maintain proper water chemistry in BWR cooling systems to prevent intergranular stress corrosion cracking of austenitic stainless steel piping and components and to minimize corrosion and erosion / corrosion-induced pipe wall thinning in single-phase and two-phase high energy carbon steel piping.

Water chemistry is also important for the minimization of plant radiation levels due to activated corrosion products.

Section 10.4.6.3 of the ABWR indicates that the i

condensate cleanup system complies with Regulatory Guide 1.56.

Section 10.4 should indicate that the system meets the guidelines published in:

EPRI NP-4947-SR, BWR Hydrogen Water Chemistry Guidelines 1987' Revision, dated October 1988.

EPRI NP-5283-SR-A, Guidelines for Permanent BWR Hydrogen i

Water Chemistry-1987 Revision, dated September 1987.

The use of zinc injection as a means of controlling BWR radiation-field build-up should be discussed.

281.16 In Section 10.4.6.3, the ABWR SSAR indicates that the condensate cleanup system removes some radioactive material, activated corrosion products and fission products that are carried over from the reactor.

More important functions involve removal of condensate system corrosion products, and possible impurities from condenser leakage to assure meeting BWR Hydrogen Water Chemistry Guidelines.

This should be discussed.

281.17 The condensate (Figure 10.4.4) and feedwater (Figure 10.4.7) system diagrams do not indicate the location of the oxygen injection into the condensate system and hydrogen and zinc oxide into the feedwater system.

This information should be provided.

281.18 Section 10.4 does not discuss design improvements involving material selection, water chemistry, system temperatures,-piping design and hydrodynamic conditions that are necessary to control erosion / corrosion.

The EPRI CHECMATE or other erosion / corrosion computer codes may be useful design tools to minimize wall thinning due to erosion / corrosion-corrosion.

The ABWR SSAR should discuss design considerations to minimize erosion / corrosion and procedures and administrative controls to assure that the structural integrity of single-phase and two-phase high-energy carbon steel piping systems is maintained.

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REQUEST FOR ADDITIONAL INFORMATION INSTRUMENTATION AND CONTROL 420.19 (7.1.2.1.6 (4))

This section states that automatic self-test is performed sequentially on all four divisions, to minimize common mode effects, and that a complete self-test sequence through all four divisions takes no more than 30 minutes.

The original response to question 19 revised this section.

What hardware and software design features are provided to allow sequencing the testing of the four divisions without violating independence / isolation criteria?

The revised section appears to allow a common centralized test driver. Illustrate with a block diagram.

420.69 (7A)

Are there any limitations on the ABWR design concerning the use of expert systems?

Any limitations on the us,e of technology not specifically described?

The original response j

does not describe an approach for determining what hardware or software developments which may occur between design certification j

and plant operation can be implemented without changes to the design certification and NRC review.

I 420.123 (15B4)

SSAR 15B.4 describes the essential multiplexing system (EMS) in some detail.

SSAR Figure 7A.2-1 states that the design is not limited to this configuration.

It is our l

understanding that the EMS design is still in a preliminary design stage.

Is SSAR 15B.4 still accurate and is the design limited to that configuration?

420.124 (15B.4)

The FMEA submitted in SSAR 15B.4 is inadequate for a safety evaluation supporting the design certification.

The L

1 FMEA appears to the staff to be oversimplified with one line item each for component failures and does not address potential software complications.

The staff requests clarification of how this FMEA was developed given that the system design has not been finalized.

The staff also believes that software failures need to be evaluated.

The failure modes investigated should include, as a minimum, stall, runaway, lockup, interruption / restoration, clock

-and timing faults, counter overflow, missing / corrupt data, and effects of hardware faults on software.

420.125 (7.4.1.4)

This section provided additional clarification of the intended use of the remote shutdown system.

The degree of independence and isolation from the Safety System Logic and Control (SSLC) and EMS are not clear.

Is it intended in the SSAR to take credit for the RSS if there is a total loss of EMS?

420.126 (7A-7)

Compared with GESSAR II, the ABWR has significantly reduced the number of input sensors by use of sharing sensors.

Provide a bases to why this does not increase potential vulnerability to common mode failures by reducing sensor diversity.

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p -. 420.127 (7) In general, the applicant should provide a cla r presentation of how the ABWR with common software and hardware modules for many functions (including SGLC logic self-test programs) conforms with IEEE 279-1971 and is at least as single failure proof as GESSAR II.

The discussion of shared sensors in 7A-7 does not address potential common mode software failures which may be capable of defeating the diverse parameters.

Additionally, tho applicant should address why diversity of software should not be a requirement to maintain system diversity.

420.128 (7A.7)

Will software be used to isolate data?

If so, 4

what are the design and qualification criteria that are to be applied?

Are there any systems which have non-Class IE software such as keyboard or display control software that interface with the Class-IE systems?

Are there any interface with the Class-IE systems which receive inputs from non-Class IE systems or other#

channels of 1E systems?

420.129 (7)

List those systems or major components in the I&C design area for which the design is not complete to the " purchase specification" level.

420.130 (Response 420.63)

In this response, a MTBF goal of 100,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> (11.4 years) is given for the essential multiplexing system.

Is this goal for one channel or the complete system?

If this goal is for the complete system, it appears to the staff that the ABWR can expect to loose control at the control room of many of the safety systems (RPS, RHR, ADS) five or six times over the lifetime of the plant.

How does this compare with the reliability / availability of multiple ESF systems in the BWR/S & 6 design (or GESSAR II)?

420.131 (19.2.3.4)

Are multiplexer and software failures included in these systems interactions and common cause failures?

420.132 (19.3.1.3.1 (b)) (Response 420.47)

Section 19.3.1.3.1 (b) states that "if core cooling is accomplished without the use of an RHR systems and the suppression pool cooling begins overheating, the suppression pool cooling mode of the RHR will be initiated by the operator." Is any manual action required prior to 30 minutes?

420.133 (19.3.1 3.1 (c) (i))

This section describes the MSIV closure sequence with the most desirable outcome requiring operator action at 30 seconds to insert rods.

If that fails the operator must inhibit ADS valves from opening and initiate SLCS within 10 minutes.

These activities do not appear to be consistent with a stated design goal of no operator action for 30 minutes following a transient.

Provide a description of how the MSIV closure sequence meets the 30 minute rule (6.3.1.1.1) same question for Loss of Offsite Power (LOOP).

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420.134'(19D.3.4)

Equipment maintenance or test unavailability are taken from GESSAR PRA and are based upon BWR experience.

In the past, 1&C has been a large contributor to system downtime.

How do these systems (RHR, RCIC) unavailability numbers take into account the new multiplexing and microprocessors?

420.135 (Table 19D.6-10) Provide the justification for a Mean Time To Repair (MTTR) of 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> for multiplexers and 30 minutes for ESF logic.-

Inverters and battery chargers have restoration time given (Table 19A.8) as 48-56 hours.

Are the multiplexers designed with all test and maintenance equipment installed?

420.136 (7A) The staff has reviewed the commitments in the SSAR and has reviewed the available documentation describing the verification and validation plans.

To date, the information has been vague, general in nature and lacking in essential detail td demonstrate conformance with ANSI /IEEE 7-4.3.2.

Does the applicant intend to enclose the V&V Plan as Appendix B of SSAR Chapter 7 or will the V&V details be left as an interface requirement?

The staff requires a formal, structured V&V plan to be in place and implemented early in the software design process.

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