ML20097D332

Affidavit of E Alarcon Re Keff & Boron Concentrations. Certificate of Svc Encl

ML20097D332
Person / Time
Site:	Comanche Peak
Issue date:	09/13/1984
From:	Alarcon E TEXAS UTILITIES ELECTRIC CO. (TU ELECTRIC)
To:
Shared Package
ML20097D278	List: ML20097D274 ML20097D309 ML20097D326 ML20097D332
References
OL, NUDOCS 8409170446
Download: ML20097D332 (13)

Text

r Attachment 3 CGCMETED U%RC a

UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION 84 SP 14 P3:26 0 BEFORE THE ATOMIC SAFETY AND LICENSING BOARD . -

as In the Matterlof )

. )

TEXAS UTILITIES ELECTRIC- ) Docket Nos. 50-445 COMPANY, _et _al. ) 50-446

)

(Comanche-Peak Steam Electric ) (Application for Station, Units 1 and 2) ) Operating Licenses)

AFFIDAVIT OF EDWARD ALARCON REGARDING K,ff AND BORON CONCENTRATIONS

'My name is Edward Alarcon. My business address is' Comanche Peak-Steam Electric Station, P. O. Box 2300, Glen Rose, Texas

.76043. I am the section head of Results Engineering for Comanche Peak Steam Electric Station ("CPSES"). In that capacity, 'I am responsible for initial fuel loading activities, precriticality testing, and other initial startup testing. A statement of my educational and professional qualifications is attached to Applicants Motion for: Authorization to Issue a License to Load Fuel and Conduct Certain Precritical Testing filed on August 7, 1984.

The purpose of this Affidsvit is to respond to the Licensing c

Board's request for additional information concerning K,gg and boron dilution, and-to identify the systems and procedures relevant to fuel-loading and precritical testing as set forth in the' Board's " Memorandum (Request for Evidence Relevant to Fuel zLoading)" dated August 24, 1984.

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Calculations Regarding K,gg The Licensing Board requested " evidence concerning the maximum K,ff to be permitted during precritical testing that analysis suggests that may be achieved during precritical testing if allicontrol rods were inadvertently removed while the boron concentration was 2000 ppm . . . .

Board Memorandum at p. 2.

-In response to the Board's first question, the maximum K,gg

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permitted _during precritical testing is established by Technical Specifications.as .990 during cold shutdown (coolant temperature

--less than or equal to 200 F) and .984 at elevated temperatures (greater than 200 F). (It should be noted that as the coolant-temperature increases, K,gg' decreases). Reactivity control requirements during refueling are based on boron concentration.

Specifically, in accordance with Technical Specifications, the boron concentration must be maintained sufficient t-o assure that the' more restrictive of tdue following reactivity conditions is mets- '(1) K,ff of .950.or less, or (2)-boron concentration of greater.than or equal to 2000 ppm. For the initial fuel loading at.CPSES, the limit of 2000 ppm boron concentration is the more restrictive limit and provides substantial conservatism as discussed below.

During fuel loading, CPSES will maintain the boron concentration in the reactor coolant system at greater than or equal to 2000-ppm as required by CPSES Technical Specifications.

The fuel-designer has provided design information and curves j l

b Ib - - - . - . - . - . . - _ -

3-related to the initial fuel design. This information was developed using methodologies descibed or referenced in Section 4.3 (" Nuclear Design") of the FSAR. The minimum boron concentration required to maintain K,gg less than or equal to . 950

- with all rods inserted is 1275 ppm. Therefore, the requirement

'for 2000 ppm is extremely conservative. During precritical testing, again the boron concentration will also be maintained at greater than or equal to 2000 ppm. This conservative administrative control exceeds the requirements of the CPSES Technical Specifications during these modes of operation.

Using conservative assumptions, the maximum K,gg expected during precritical testing (either hot or cold) was calculated to be .984. The conditions associated with this calculation are a boron concentration of 2000 ppm, a coolant temperature of 68 F and the most reactive control rod bank withdrawn.

In response to the Board's second question regarding the Keff which may be achieved assuming a 2000 ppm boron concentration and all control rods fully withdrawn, I would like to first state that the likelihood of all control rods being simultaneously fully

. withdrawn is virtually nonexistent. Except during specific tests on the. rod control, rod drive, and reactor trip systems, these systems will be deenergized, precluding inadvertent rod withdrawal. Also, during testing of these systems, all control rod movement will be tightly controlled by detailed step-by-step test procedures. These procedures also require increased m--~ ,--.wes--e- e,---wn ,-v,~, - . - ---.-,-------,----.w- s-- - , - w-.,-- - - , , - ,-v - - - - - ~ - - - - - , ,

monitoring of nuclear instrumentation and rod position indication to preclude unauthorized rod configurations or inadvertent reactivity additions during control rod movements. Finally, following those tests which require control rod withdrawal,

-positive restoration steps are taken to prohibit further control rod motion. These steps include opening the reactor trip breakers and deenergizing the rod control motor generators to remove power from the control rod drive mechanisms and thereby preclude rod withdrawal.

In any. event, even if all control rods were fully withdrawn at the worst case coolant temperature of 69 F, using conservative calculations K,gg would be only .932, still well below the Technical Specificaticns limit of.990. Indeed, conservative calculations reflect that assuming a coolant temperature of 68 F and all control rods fully withdrawn, the boron concentration could drop to 1390 ppm and K,gg would still be below .990.

Maintaining Boron Concentrations One Licensing Board requested evidence "that non-borated water will never be injected into the core, substantially diluting the boron below 2000 ppm." Board Memorandum at p. 2. This will provide the evidence requested.

Makeup water to the Reactor Coolant System ("RCS") is

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provided either from the volume control tank of the Chemical and Volume Control System ("CVCS") or from the Refueling Water Storage Tank ("RWST"), a large tank normally containing several hundred

['

thousand gallons of borated water. (Highly borated water, approximately 7000 ppm, is also available from the boric acid tanks in the CVCS). Prior to fuel loading, the CVCS and RWST, as well as the Reactor Coolant System, are borated to at least 2000 ppm.

Immediately prior to commencement of the fuel loading seg"ence, the boron concentration of the RWST is again established and1then maintained greater than or equal to 2000 ppm as required by CPSES Technical Specifications. Also, as required by this test procedure, the Reactor Coolant System is sampled and analyzed for boron concentration at several places to assure uniformity of the 2000 ppm minimum boron concentration. Finally,.also as a

1. - prerequisite to initial fuel loading, certain valves in the CVCS are closed and secured in the closed position. These valves block all flow paths that could allow unborated makeup water to reach the reactor coolant system. Therefore, any makeup which-is required-during refueling will be borated water supplied from the RWST.

It should be noted that once the proper boron concentration is verified immediately prior to commencement of initial fuel l

loading, a. monitoring program is initiated and' maintained

-throughout the initial fuel loading sequence to verify that the boron concentration remains at the desired level, at least 2000 ppm. This monitoring program requires sampling and chemical analysis of the boron concentration by a chemistry technician l

l

every four' hours. .The results of the analysis are reported to the

. control room =for review by the operators and the initial startup test engineer on duty, who compares the results with the boron concentration that should be in the system. If the boron concentration decreases below 2000 ppm or the boron concentration deviates by_20 ppm or more between samples, test procedures require the operator to. stop the initial fuel loading process and

-initiate investigative and' corrective actions.

Upon completion of the initial fuel load, the precritical test sequence begins. During the precritical test sequence, the Reactor Coolant System will be restored to normal operation with the reactor vessel head reassembled and-the CVCS in normal operation. The charging flow to and letdown flows from the.RCS are automatically controlled by the CVCS to maintain a constant RCS-coolant inventory.- Also, within the.CVCS, a boric acid' blend system is available to allow the operator to match the makeup

. water's boron concentration to that of the RCS during normal

-charging.

' Prior to the commencement of the actual. testing, the RCS boron concentration is sampled and analyzed to verify a boron concentration of at.least 2000 ppm. As stated earlier, this requirement of 2000 ppm during this test phase is extremely conservative, exceeds the requirements of the CPSES Technical Specifications and provides a substantial shutdown margin. A monitoring program is initiated and maintained on a frequency of t ;-

one.per shift ( i . e! . , 'every 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />) to ensure that the boron concentration of the react'or coolant, system remains greater than or equal to 2000 ppm. If the boron concentration decreases below 2000 ppm, all activities which could add positive reactivity to the core are' halted and the boron concentration is restored ' to at least 2000 ppm.

Prevention, Detection, and Mitigation of An Inadvertent Boron Dilution The CPSES~ Final Safety Analysis Report, section 15.4.6 addresses the causes and automatic actions associated with an inadvertent boron dilution event. Some of that information is summarized here along with some pertinent remarks concerning 4

initial fuel loading and precritical testing.

As previously stated, during fuel loading, the boron concentration.is established and. continuously maintained at greater.than or equal to 2000 ppm. .Most importantly, all

' potential sources of unborated water are isolated from the RCS by closing and securing closed certain valves in the CVCS.- Any l- required makup during refueling will be borated water from the RWST'which is maintained within strict Technical Specification L

1 requirements. Therefore, an uncontrolled boron dilution during

[

the initial fuel loadingLis virtually-impossible.

y-Although the above is true, the boron concentration is still.

. monitored every four hours. Also, during this test sequence, the >

nuclear instrumentation, which has readouts in the continuously

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i i manned control. room, and other special instrumentation will be l

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L

8-closely monitored to detect and trend the reactivity in the core.

Any unexpected reactivity changes would require the immediate -

suspension-of initial fuel loading actions and the initiation of investigative actions as to the cause of such unlikely changes.

During the : precritical - test sequence, the RCS is established and' maintained at a conservative limit of greater than or equal to 2000 ppm boron concentration. The only credible cause of an

- inadvertent boron dilution is described in FSAR Section 15.4.6 and involves a malfunction in the CVCS. Administrative and procedural controls-have been established to effectively preclude inadvertent injection of unborated makeup water into the RCS from the CVCS due to operator error. Operation of the CVCS is performed in accordance with procedures which are step-by-step in nature, and which are performed under the direction of trained and licensed reactor operators.

The boron monitoring program on each shift will detect any changes in boron concentrations. Further source range neutron instrumentation level indication is continuously logged on strip charge recorders, so that the operator may detect trends, such as changes in source range level due to boron dilution. It should be J

noted that the source range channels in the control room also have audio indication. The audio indication is in the form of

" clicks" (such as a typical radiation detecto ) which continuous increases or decreases in frequency based on neutron flux changes in the reactor core.- Any significant change in boron s

v v e~- ..-.--..e,,- ,.e + , m ,g.,., .,,mg e,e. p y-- p. -- ,,,.-mn- vp , ,.mw, y ,,w,- py--+- - - - , , , ,,9 9,w ve.-,en

_9-concentration in the Reactor Coolant System would result in a

' substantial..and very noticeable change in the " clicking" 7

frequency.

Finally, FSAR Sections 7.6.11 and 15.4.6 describe the components provided to mitigate the . consequences of an inadvertent boron dilution at CPSES. Briefly, in the-unlikely event of an inadvertent boron dilution transient the source range nuclear instrument' ion will detect a doubling of the neutron flux.by

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. continuous comparison of the current. source range flux to that of approximately ten minutes earlier.- This flux-doubling system is a safety-related redundant system. Upon detection of the flux doubling, an alarm is sounded for the operator and valve movement to terminate.the dilution and start boration is automatically

-initiated. No immediate operator action is required. These

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automatic actions'are carried out to stop any approach to criticality and regain any lost shutdown margin.

In conclusion,-based on the foregoing, in my professional opinion, it is a virtual impossibility for a boron dilution event to be initiated and continue until a K,ff of .990 is exceeded.

t Selection of Relevant Systems and Procedures t The Licensing Board requested information concerning the adequacy of QA/QC oversight ' activities on systems that may be

. called upon to function during fuel. loading and precritical

. testing to protect public health and safety. The Board stated I

that.at least four systems were included in this category, i.e., j l

10 -

'(1) boron addition and monitoring equipment, (2) reactor monitoring equipment, (3) fuel loading equipment, and (4) reactor protection systems. Board Memorandum at p. 2. In response to the

-Board's request,'I conducted an evaluation of all plant systems to determine .the systems that fell into the category specified by the

" The list of ten systems / equipment Boa rd ,' as noted above.

groupings attached to.Mr. Vega's Affidavit reflects my determination of the CPSES specific systems requested by the Board, plus any other components or systems that might be required to function.to mitigate any inadvertent' event' such as boron dilution. It should also be noted that the CPSES Technical

' Specifications will require additional equipment or systems to be

. operable depending upon the plant-operational mode.

. The Board also requested information regarding the

" appropriate QA/QC procedures" needed for fuel loading and precritical. testing.(Board Memorandum at p. 2).

In response to the Board's request, I conducted a review to determine which procedures fell into this category. Based or my review, these 21 initial startup.(ISU) procedures identified.in the attachment to Mr. . Deviney's Affidavit are tdue major controlling documents requested by the Board. As noted in Mr. Deviney's Affidavit, 1

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, other. routine plant procedures may be referenced in these ISU procedures or may be used to support the activities of fuel load and precritical testing. ,

Wf Edward Alarcon County of Somervell )

)

State of Texas )

Subscribed and sworn to before me this 11 day of September, 1984

. AU/n h&l/2 Notary blic My commission expires: 09/04/85 1

-. . - , - . . . . , . . , _ - . - . . _ . . . , _ - . . - . . . . . _ , . . _ . - - _ . . ~ . . . _ . , . . . ~

f..

(

DCt eCE" 05NA0 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION 84 SEP 14 P3 :26 BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the Matter'of ) #

C

)

TEXAS-UTILITIES ELECTRIC ) Docket Nos. 50-445 and COMPANY, - _al.

et )

)

50-446 (Comanche Peak' Steam Electric ) (Application for

' Station, Units 1 and 2)

) Operating Licenses)

CERTIFICATE OF SERVICE-

. I hereby certify that copies of the foregoing " Applicants'

. Supplement.to Motion for Authorization Pursuant to 10 C.F.R.' $

50.57(c)" in the above-captioned matter were served upon the following persons.by hand delivery,* by overnight delivery,** or by: deposit in the United States mail,*** first class, postage

-prepaid, this.13th day of September, 1984:

• Peter B.fBloch, Esq. *** Chairman, Atomic Safety and Chairman, Atomic Safety and- Licensing Appeal Panel Licensing Board U.S. Nuclear Regulatory-U.S. Nuclear Regulatory Commission Commission Washington, D.C. 20555 '

Washington, D.C. 20555 .

• • Mr. William L. Clements

• Dr. Walter H.' Jordan Docketing & Service Branch ,

881. West Outer Drive U.S. Nuclear Regulatory

Oak Ridge, Tennessee 37830 Commission Washington, D.C. 20555-

' **Dr. Kenneth A. McCollom Dean, Division of Engineering Architecture and Technology *Stuart A. Treby, Esq.

Oklahoma State University Office of the Executive 2 Stillwater, Oklahoma .

74074 Legal Director U.S. Nuclear Regulatory

~ ***Mr. John Collins- Commission Regional Administrator, Washington, D.C. 20555 Region IV-

'U.S. Nuclear Regulatory *** Chairman, Atomic Safety and

' Commission Licensing Board Panel 611 Ryan Plaza Drive U.S. Nuclear Regulatory 1: Suite 1000 Commission Arlington, Texas 76011 Washington, D.C. 20555 4

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• • • Renea Hicks, Esq. **Mrs. Juanita Ellis Assistant Attorney General President, CASE Environmental Protection 1426 South Polk Street

. Division Dallas, Texas 75224 P.O. Box 12548 Capitol Station

• Ellen Ginsberg, Esquire Austin,-Texas 78711 Atomic Safety and Licensing Board Panel

• • • Lanny A. Sinkin U.S. Nuclear Regulatory

114 W. 7th Street Commission-Suite 220 Washington, D.C. 20555 Austin, Texas 78701

' Sanford L. Hartman

'_ cc: John W. Beck Robert Wooldridgei Esq.

_. _ _ _ _ . _ , _ _ . _ _ - _ __ _ _ _ - _ . - _ _ _ _ , - . _ _ . _ _ -