ML19347D973

Proposed Findings of Fact & Conclusions of Law in Form of Initial Decision.Certificate of Svc Encl

ML19347D973
Person / Time
Site:	Mcguire, McGuire
Issue date:	04/08/1981
From:	DUKE POWER CO., DUQUESNE LIGHT CO.
To:
Shared Package
ML19347D970	List: ML19347D969 ML19347D973
References
NUDOCS 8104140545
Download: ML19347D973 (71)

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UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION Ofi.:e er N ,c C;h'U J, .'a,;a k

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BEFORE THE ATOMIC SAFETY AND LICENSING BOARD g In the Matter of )

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DUKE POWER COMPANY ) Docket Nos. 50-369

) 50-370 (William B. McGuire Nuclear )

Station, Units 1 and 2) )

APPLICANT'S PROPOSED FINDINGS OF FACT AND CONCLUSIONS OF LAW IN THE FORM OF A SUPPLEMENTAL INITIAL DECISION In accordance with 10 CFR $2.754, Applicant, Duke Power Company, hereby submits Proposed Findings of Fact and Conclusions of Law in the form of a Supplemental Initial Decision.

Respectfully submitted, J. Michael McGarry, III Malcolm H. Philips, Jr.

DEBEVOISE & LIBERMAN 1200 Seventeenth Street, N.W.

Washington, D.C. 20036 (202) 857-9800 Of Counsel:

William L. Porter Associate General Counsel DUKE POWER COMPANY April 8, 1981 1

810.41.40644

UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD -

Robert M. Lazo, Chairman Dr. Emmeth A. Luebke, Member Dr. Richard F. Cole, Member In the Matter of )

)

DUKE POWER COMPANY ) Docket Nos. 50-369

) 50-370 (William B. McGuire Nuclear )

Station, Units 1 and 2) )

SUPPLEMENTAL INITIAL DECISION (REOPENED OPERATING LICENSE PROCEEDING)

I. BACKGROUND

1. The background of this proceeding is set forth in the Initial Decision (Operating License Proceeding) which was issued on April 18, 1979, Duke Power Company (William B.

McGuire Nuclear Station, Units 1 and 2), LBP-79-13, 9 NRC 489 (1979). This decision is incorporated herein by refer-ence. Therein, the Atomic Safety and Licensing Board ("Li-censing , Board") focused upon the issues in controversy. 1/

-1/ The sole issues in controversy were: (1) need for power; (2) cost-benefit analysis of alternative genera-tion; (3) seismology; (4) stud bolts (5) financial qualifications; and (6) solar power. The stud bolt issue was withdrawn due to Carolina Environmental Study Group's ("CESG") failure to pursue the matter in accordance with the ruling of the Licensing Board.

McGuire, supra, 9 NRC at 491.

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On the basis of specific findings of fact and conclusions of l law, the Licensing Board ordered that the Director of the office of Nuclear Reactor Regulations, upon making requisite findings with respect to uncontested matters not embodied in the Initial Decision, was authorized to issue operating licenses for the two units. McGuire, supra, 9 NRC at 547-8.

However, the Licensing Board stayed the effectiveness of the Initial Decision "until further order by the Board following the issuance of a supplement to the Nuclear Regulatory Commission ("NRC") Staff's Safety Evaluation Report ("SER")

addressing the significance of any unresolved safety issues."

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2. On May 23, 1980, the NRC Staff issued the afore-mentioned supplement to the SER. Supplement No. 3 to NUREG-0422 (May 1980) (Staf f Exhibit H) . '

3. On May 30, 1980, Duke Power Company (" Applicant")

a moved the Licensing Board to lift its stay of the Initial Decision.

4. On June 9, 1980, Intervenor, CESG, filed a response opposing Applicant's Motion to lift the stay, and a Motion requesting the reopening of the McGuire operating license hearing and the admission of new contentions regarding "the consequences of the combustion of a significant hydrogen release in a Westinghouse pressure suppression containment...."

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5. On August 15, 1980, CESG amended its Motion to reopen and advanced four contentions for considera-tion. 2/ For a listing of these contentions, see paragraph 11.

6. By Memorandum and Order of November 25, 1980, the Licensing Board granted CESG's Motion to. reopen and admitted CESG's four Contentions and denied Applicant's motion to lift the stay of the Initial Decision.

7. Pursuant to 10 CFR $2.715(c), on December 23, 1980 and January 13, 1981, Mecklenburg County and the City of Charlotte, respectively, requested participation in the reopened hearings as interested government bodies. By Order 4

of January 26, 1981, the Licensing Board approved both requests.

8. By Conference Calls of December 23, 1980, January 14, 1981, January 28, 1981, and February 12, 1981, and by written Order of January 29, 1981, the Licensing Board

-2/ On November 7, 1980, CESG filed a Motion setting forth two additional contentions for consideration.

By Memorandum and Order of February 13, 1981, the Licensing Board denied admission of these contentions.

e o established the appropriate discovery 3/ and hearing schedule. 4/

9. Public hearings regarding the issues raised by CESG were held in Charlotte, North Carolina on February 24-27, March 3-6, March 10-13, and March 17-19, 1981. The parties presenting evidence at the hearings were Applicant, NRC Staff, and CESG. Mecklenburg County and the City of Charlotte participated pursuant to 10 CFR $2.715(c).

10. The decisional record in this proceeding 5/

3/ The Licensing Board notes that discovery in 4his pro-ceeding had been ongoing since June 9, 1980, when CESG filed its first discovery request with the Applicant.

-4/ Pursuant to a Stipulation among all parties filed with the Board on December 19, 1980, Applicant and Intervenor were to file proposed testimony on January 26, 1981, the Staff on February 2, 1981, and the hearing was to commence on February 9, 1981. This schedule was modified by the Board during a January 28, 1981 confer-ence call and in the Board's January 29, 1981 Order, such that Applicant was required to file proposed testimony on February 9, 1981, CESG on February 12, 1981, and the Staff on February 17, 1981, and the hearing was to commence on February 24, 1981. On February 4, 1981, CESG filed a Motion for reconsidera-tion of the hearing schedule. During the conference call of February 12, 1981, such Motion was denied.

-5/ The Licensing Board notes that each member of the Board has visited the McGuire site and examined, inter alia, the control room. In addition, Judge Cole, inspected the inside of the containment to include the ice condenser and upper plenum areas, the subjects of significant discussion in this proceeding.

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consists of the transcripts of the evidentiary hearings referred to above, all material received into evidence by the Licensing Board during such hearings 6/, and the decisional record established in the previously issued Initial Decision in the operating license proceeding.

II. BASIC FINDINGS

11. CESG contentions in this proceeding are as follows:

l Contention 1: The licensee has not demonstrated that, in the event of a loss-of-coolant accident at McGuire:

1. substantial quantities of hydrogen (in excess of the design basis of 10 CFR $50.44) will not be generated; and

2. that, in the event of such generation, the hydro-gen will not combust; and

3. th at, in the event of such generation and com-bustion, the containment has the ability to with-j stand pressure below or above the containment design pressure, thereby preventing releases of off-site radiation in excess of Part 100 guideline

values.

Contention 2: Neither licensee nor NRC staff has

, demonstrated that a McGuire ice containment will not breach as the result of the rapid combustion of quan-

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tities of hydrogen which a dry containment would withstand.

-6/ At the close of the hearing, the Licensing Board granted the Staff's request to hold the record open for the limited purpose of possible inclusion of the results of the Staff review of a discrete issue regard-ing polyurethane foam. Tr. 5252. The results of the Staff review were submitted in an affidavit filed on all parties on March 27, 1981. The Staff's affidavit and all responsive affidavits are, thus, also included as part of the decisional record in this proceeding. An index of exhibits is attached hereto as Appendix A.

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Contention 3: Neither licensee nor NRC staff has demonstrated that the emergency planning radius of 10 miles is sufficient for protecting the public from the radioactive releases of a low pressure, ice condenser containment ruptured by a hydrogen explosion.

Contention 4: Licensee and NRC planning do not pro-vide for crisis relocation which would be required as a result of containment breach and radioactive particle release.

12. CESG Contention 2 attempts to raise as an issue a comparison of the structural capabilities of the McGuire containment and other larger centainment structures. The Licensing Board views Contention 2 as an expression of concern regarding the ability of the McGuire containment to withstand the effects of a hypothetical hydrogen combustion.

In that such concern is embraced within CESG Contention 1, specific findings regarding Contention 2 are unwarranted. 7/

13. During the course of the hearing, it became clear that the issues raised by Contentions 3 and 4 relating to emergency planning are not reached unless CESG is successful regarding Contention 1. Tr. 2829-34 and 3434-5. Evidence regarding Contentions 3 and 4 was, accordingly, deferred pending this Board's ruling on Contention 1. Tr. 3481-3.

-7/ The Licensing Board notes th at , as discussed in these findings, the McGuire containment can withstand the effects of rapid combustion of hydrogen which a dry containment could withstand for TMI-type accidents, due to the McGuire facility design which utilizes the ice condenser and distributive ignition systems.

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14. In sum, the issues addressed in this reopened proceeding, and those upon which this Supplemental Initial Decision will focus, relate to CESG Contention 1. In its August 15, 1980 Revised Motion to Reopen, CESG notes that Contention 1 is the precise contention advanced as Sholly Contention 11 in the Three Mile Island Restart proceeding (Docket No. 50-289 (Restart)). In the TMI Restart proceed-ing the Commission issued two decisions regarding the proper scope and focus of litigation on matters involving such hydrogen generation. Metropolitan Edison Company (Three Mile Island Nuclear Station, Unit No. 1), CLI-80-16, 11 NRC 674 (1980) and Order of September 26, 1980 (Docket No.

50-289 (Restart)). In that the hydrogen issue raised in the TMI Restart proceeding basically parallels the issue CESG raises here, the Commission decisions discussed below, are applicable to this proceeding.

15. The issue of hydrogen generation was brought before *the Commission in the TMI Restart proceeding in the form of two certified questions:

1. Whether the provisions of 10 CFR 50.44 should be waived or exceptions made thereto in this proceeding where a prima facie showing has been made under 10 CFR 2.758 that hydrogen gas generation during the TMI-2 accident was well in excess of the amount required under 10 CFR 50.44 as a design basis for the post-acci-dent combustion gas control system for TMI-1.

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2. Whether post-accident hydrogen gas control should be an issue in this proceeding where post-accident hydrogen gas control was perceived to be a serious problem and was in fact a problem during the TMI-2 accident. [Three Mile Island, supra, 11 NRC at 674-5.]

In its ruling regarding the certified questions, the Commission declined to waive or except the hydrogen gener-ation provisions emoodied in 10 CFR $50.44. Id. 8/

However, the Commission stated that litigation of the hydrogen generation issue was acceptable in indivdual licensing proceedings under 10 CFR Part 100 (Id. 11 NRC at 675) subject to the following prerequisites:

The Commission believes that, quite apart from 10 CFR 50.44, hydrogen gas control could properly be litigated in this proceeding under 10 CFR Part 100. Under Part 100, hydrogen control measures beyond those required by 10 CFR 50.44 would be required if it is determined that there is a credible loss-of-coolant accident scenario entailing hydrogen generation, hydrogen combustion, containment breach or leaking, and offsite radiation doses in excess of Part 100 guideline values. [(empha-sis supplied) Id. 11 NRC at 675]. 9/

-8/ The Commission noted that it is planning a broad rule-making proceeding regarding degraded core conditions including measures to deal with hydrogen generation in the event of such degraded core' conditions. Id. 11 NRC at 675. The degraded core rulemaking effort will consider, inter alia, accidents outside the current design basis accident envelope (i.e., incredible accidents) including core melt / slump accidents. See 45 Fed. Reg. 65474 (October 2, 1980).

-9/ The record reflects the reference to numerous accident sequences. The Licensing Board, as discussed herein, has limited its focus to accidents demonstrated to be credible; the degraded core rulemaking provides a forum for the discussion of other accidents.

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,9-Commissioners Gilinsky and Bradford in their dissent to the Commission's September 26, 1980 Order denying reconsideration of CLI-80-16 make clear where the burden of establishing a credible accident lies:

Moreover, Chairman Ahearne and Commissioner Hendrie are, in effect, saying that even after experience has amply demonstrated the inadequacy of saftey regulations covering the internal components of the reactor the burden is still on a challenger to lay out a specific accident sequence to the Commission which leads to containment failure and public radiation exposures in excess of those permitted by Part 100. [TMI (Restart),

supra, Order, dissenting opinion, slip op. at p. 2 (September 26, 1980).]

Based on the above Commission decisions, CESG's hydrogen generation issue edbodied in its Contention 1 is subject to litigation in this proceeding pursuant to 10 CFR Part 100 if CESG can demonstrate a " credible" 10/ accident scenario involving hydrogen production resulting in offsite doses in excess of 10 CFR Part 100 limits.

16. At the outset of the hearing, Applicant stated that it would not stand on formalities regarding CESG's burden of establishing that the TMI accident was credible.

(Tr. 2816). Rather, Applicant took the lead and presented  ;

evidence to the effect that a TMI accident resulting in excessive hydrogen generation leading to offsite doses I

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The Commission noted that the " likelihood of the acci-dent is the key to credibility." TMI Restart, supra,

! Order, Slip Op. at p. 3 (September 26, 1980).

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in excess of Part 100 limits was not a credible accident scenario at the McGuire facility. Id. As discussed in this decision, other than the TMI accident scenario, CESG has failed to present any evidence regarding a credible accident scenario at the McGuire facility which could cause excessive hydrogen generation leading to offsite doses in excess of Part 100 limits. Thus, pursuant to the Commission decisions in the TMI Restart proceeding, the only issue in controversy and subject to resolution in this proceeding is whether a TMI accident resulting in etcessive hydrogen generation leading to offsite doses in excess of Part 100 limits is credible at the McGuire facility.

17. In making the findings of fact and conclusions of law which follow, the Board considered the entire record of the proceeding and all of the proposed findings of fact and conclusions of law submitted by the parties. Each of the proposed findings of fact and conclusions of law which is not incorporated directly or inferentially in this Supple-mental Initial Decision is rejected as being unsupported in law or fact or as being unnecessary to the rendering of this Decision.

The Board is guided in this operating license proceed-ing by Appendix A,Section VIII of 10 CFR Part 2, which in subsection (b) provides that the Board will make findings on matters in controversy among the parties.

III. MATTER IN CONTROVERSY Whether the TMI Accident Resulting In Excessive Hydrogen Production Leading To Offsite Doses in Excess of Part 100 Is Credible At the McGuire Facility

18. Uncontroverted evidence has clearly estab-lished that excessive hydrogen produced during the TMI accident was a direct result of a reaction between the zirconium in the fuel cladding and steam 11/ during a loss-of-coolant accident which lead to an inadequate core cooling situation. 12/ Control of such reaction is pro-vided by the emergency core cooling system ("ECCS") which is designed to prevent an inadequate core cooling situ-ation which could result in high temperatures of the core 11/

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Other potential methods of hydrogen production are much slower and are easily handled by conventional hydrogen control systems such as the hydrogen recombiners. NRC Staff Testimony following Tr. 4353 regarding Analysis of Hydrogen Control Measures at p. 2-3 (February 1981)

(" Staff Testimony Regarding Hydrogen Control") .

--12/ The pertinent sequence of events which occurred at TMI resulting in a hydrogen generation accident are (1) a loss of feedwater transient resulting in high reactor coolant system pressure which was relieved by the pressurizer relief valve, (2) failure of the relief valve to close resulting in a continued loss-of-coolant, (3) premature operator interference with the emergency core cooling system resulting in inadequate cooling of the reactor core and excessive core temperatures, and (4) production of hydrogen from the reaction of approxi-mately 45% of the =irconium clad and steam in the presence of the excessively high temperatures. Tr.

2870-3, 3086-89, 3374, 4469-70 and Staff Testimony Regarding Hydrogen Control at pp. 2-3.

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and excessive hydrogen production. 13/ The primary cause of excessive hydrogen generation at TMI was

--13/ Regulations regarding design of the ECCS are based upon the results of a major rulemaking proceeding to which CESG was a party (See CESG's " Motion By Intervenor With Respect To ECCS Issues" (May 31, 1972) filed in the McGuire Construction Permit proceeding). Rulemaking Hearing (Acceptance Criteria For Emergency Core Cooling Systems For Light Water Cooled Nuclear Power Reactors)

RM-50-1, CLI-73-39, 6 AEC 1085, 1099 (1973). That rulemaking resulted in, inter alia, the strict criteria regarding ECCS design contained in 10 CFR }50.46 and Appendices A and K to 10 CFR Part 50, which includes the criteria that (1) the ECCS must be able to perform its function even assuming "the most damaging single failure of ECCS equipment has taken place" (Section D.1, Appendix K to 10 CFR Part 50) and (2) the ECCS must be able to transfer heat from the reactor core following any loss of reactor coolant at a rate such that . . . (3) clad metal-water reactions are limited to negligible amounts." (Criterion 35, Appendix A to 10 CFR Part 50). In this regard, the NRC Staff has evaluated the McGuire ECCS and concluded that it is acceptable. See NUREG-0422, " Safety Evaluation Report Related To Operation Of McGuire Nuclear Station, Units 1 and 2," Section 6.3 (March 1978) Staff Exhibit B; Supplement 2 to NUREG-0422 Section 6.3 (March 1979)

Staf f Exhibit G. In addition, in the construction permit hearings regarding the McGuire facility, a significant amount of testimony was introduced regarding the adequacy of the ECCS. LBP-73-7, 6 AEC 92, 104-106 (1973). In the Licensing Board's Initial Decision issued in that proceeding, the Licensing Board found that "the emergency core cooling system ("ECCS") will be designed to provide emergency core cooling during those postulated accident conditions where it is assumed that mechanical failures occur in the reactor coolant system piping resulting in a loss-of-coolant from the reactor vessel greater than the available coolant makeup capacity using normal operating equip-ment." Id. at 104.

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the operator action of prematurely interfering with opera-tion of the ECCS, thus allowing an inadequate core cooling situation to exist resulting in an excessive zirconium-steam reaction. Applicant Testimony of K.S. Canady, L.A. Reed and H.B. Enrron Regarding McGuire Operation Relating To Hydrogen Generation following Tr. 2864 at p. 1 (" Testimony of Canady Panel I"). 14/ Indeed, if the operators at TMI had not prematurely terminated or interfered with the ECCS there would not have been excessive hydrogen generation.

Tr. 2870.

19. Applicant testified that measures taken at the McGuire facility subsequent to the TMI accident in the areas of personnel, equipment, procedures and training as discussed below, effectively preclude improper operator termination of the McGuire ECCS. Testimony of Canady Panel I at p. 1.

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See also Three Mile Island, supra, 11 NRC at 675, wherein the Commission stated:

We are, of course, aware that the Three Mile Island accident resulted in hydrogen being generated far in excess of the hydrogen generation design basis assumptions of 10 CFR 50.44. This was because the operator interfered with actual ECCS operation with the result that the safety system did not operate as designed and as $50.44 assumed it would operate.

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. . 1 Personnel

20. Changes in personnel include new technical speci-fication requirements that (1) in addition to a Reactor Operator, a Senior Reactor Operator must be present in the control room at all times, and (2) a Technical Advisor to the Shift Supervisor must be present on all shifts and available to the control room within ten minutes. 15/ Id.

at p. 2. These changes provide additional expertise in the control room. Id. In that an ECCS termination decision will be made by the Senior Reactor Operator with input available from the Shift Technical Advisor and the Reactor Operator, this change provides further assurance that the ECCS will not be prematurely terminated by operator action.

Id-Eauipment

21. Equipment modifications made at McGuire subse-quent to the TMI accident include installation of a subcool-ing monitor to monitor the approach to an inadequate core cooling situation. 16/ Id. at p. 3. See also, Tr. 2925-7, 15/

This Staffing requirement sets forth the current regulatory position. Tr. 3028-32. In addition, Applicant's current staffing procedures calls for two licensed reactor operators in the control room instead of one, however, the second reactor operator may be absent for short periods of time. Tr. 2880-1.

16/ Applicant testified that alarms are also provided to warn the operator of the approach to a potential inadequate core cooling condition. Testimony of Canady Panel I at 3.

2983, 3009-12. In addition, Applicant is planning to install a reactor vessel level measurement system at McGuire which is designed to monitor the water level in the reactor and provide further indication of an approach to an inade-quate core cooling situation. Testimony of Canady Panel I at 3. See also Tr. 2928-31.

Procedures

22. Changes in administrative and operating procedures include (1) a redefining of the shift supervisor's primary responsibilities and duties to further emphasize safe operations of the plant, (2) new shift turnover checklists, (3) more stringent restrictions on overtime (Tr. 2951) and (4) more stringent controls on verification of system availability. Testimony of Canady Panel I at pp. 3-4. Such changes will further reduce the possibility of any operator error which could lead to premature termination of the ECCS. Id. at p. 4.

23. With regard to emergency procedures, Applicant testified that prior to the TMI accident such procedures required an operator to first identify the accident which was in progress and then take corrective actions based on the particular procedure for that accident. Id. at p. 5.

Subsequent to the TMI accident, emergency procedures have been developed at McGuire requiring operator actions in I response to objective control room indications rather than

in response to the operator's subjective determination of the accident in progress. Id. In this regard, emergency procedures now require that prior to operator termination of

-the.ECCS, four specific criteria must be verified as being within acceptable limits. Id. 17/ If any of the four criteria are not met, the procedure directs that ECCS operations cannot be te rminat ed . Id. If the four criteria are met, an inadequate core cooling situation cannot exist and generation of excessive hydrogen is impos sible . Id.

All licensed operators have been thoroughly instructed in the use of such procedures. Id. In sum, operator com-pliance with these procedures precludes the premature operator termination of ECCS operations thereby preventing inadequate core cooling and excessive hydrogen generation.

Id. at co. 5-6.

17/ The specific criteria are as follows:

(1) Reactor coolant system pressure is greater than a specified minimum value and increasing, and (2) Pressurizer level is greater than a specified minimum value, and (3) The reactor coolant system is subcooled by greater than 50*F, and (4) Adequate auxiliary feedwater flow for core heat  ;

removal is injected into at least one non-faulted steam generator. [ Testimony of Canady Panel I at

p. 5].

See also Tr. 3013-6 wherein the basis for these cri-teria is discussed.

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Training

24. Applicant testified that with regard to train-ing, candidates for the operator training program are employed by Applicant for several years before being selected. Tr. 2875-6. Screening of candidates for the training program includes consideration of aptitude test results, seniority, training grades throughout employment, and employment evaluations. Tr. 2875-80. The operator training program is a lengthy (i.e., over 2-1/2 years) and intensive formal program that uses an effective mix of formal classroom presentations 18/, research reactor training, on-the-job training (using task lists), simulator operation and both written and oral examination. Testimony of Canady Panel I at p. 6: Tr. 3000-7; Section 13.2 of the McGuire Final Safety Analysis Report ("FSAR"). 19/

Instructors conducting the operator training program at 18/

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The record reflects the extensive training a potential operator is subjected to. Tr. 3000-6. This training focuses on instruction in power plant operating prac-tices and nuclear theory. Id. Specific course material includes electric theory, heat transfer, fluid flow, thermodynamics, chemistry, physics, mathematics, health physics, reactor theory, nuclear systems, transients, radioactive theory, radiation detection and instrument control theory. Id. See also 10 CFR ((55.21 and 55.22.

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Applicant testified that operators received training regarding the monitoring and reading of indicators in the control room (Tr. 2958) and on actions involving detecting and responding to false readings (Tr. 2967). l l

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McGuire are, with the exception of one Reactor Operator, all holders of a Senior Reactor Operator license. Tr. 2852.

Prior to receipt of a Reactor Operator license, each candi-date is required to comply with all appropriate provisions of 10 CFR Part 55, to include successful completion of an extensive operator examination. Tr. 3028-9. 20/ In addition, each licensed operator is required to undergo annual requali-fication training that consists of formal classroom presenta-tions and simulator operations. Testimony of Canady Panel I at p. 6, Tr. 3000-7, and Section 13.2 of the McGuire FSAR.

See also 10 CFR Part 55, Appendix A. 21/ Subsequent to the TMI accident, the training program has been revised and expanded to reflect the lessons learned from the acci-dent. Testimony of Canady Panel I at pp. 6-7; and Tr. 2852, 2874, 2879, and 3039. Such revisions include the addition of a TMI-type accident scenario in the simulator portion of

--20/ Applicant testified that at the conclusion of the train-ing the graduate is an expert in nuclear operations and has "what it takes to safely operate a nuclear. power plant." Tr. 3006.

--21/ Euch requalification training includes approximately 48 hcurs per year on the simulator (Tr. 2991) responding to simulated emergencies which includes the TMI-accident

, scenario (Tr. 2874). Applicant testifed that during l operations McGuire would use five operational shifts:

l 3 in shift operation, 1 off duty and 1 in training.

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- l the training program. Testimony of Canady Panel I at 7. 22/

Significantly, one of the basic precepts engrained into l prospective operators at McGuire even prior to the TMI accident, and even more so since TMI, is the priority associated with the avoidance of an inadequate core cooling situation. Tr. 2872. Operator adherence with the training received precludes the premature termination of the ECCS, thereby preventing inadequate core cooling and excessive hydrogen generation. Testimony of Canady Panel I at 8.

25. In conclusion, Applicant testified that in the event of a loss-of-coolant accident, such as which occurred at TMI, premature termination of ECCS operation by the operating staff at McGuire is not a credible accident scenario (Id.), i.e., that such a scenario is so remote that in their professional judgement it will not occur at McGuire. Tr. 2993-4.

26. Applicant also testified that in the incredible event of operator premature termination of ECCS operations, emergencp procedures require that readings of the four termination criteria parameters be continuously checked and recorded in a log every 15 minutes for a two hour period following such termination. Testimony of K.S. Canady, L.A.

--22/ In this regard, Applicant testified that each of its l

licensed operators at McGuire, at the time of start-up, i will have been exposed to a TMI-type accident on the

, McGuire simulator at least 3 times and more probably l 6-8 times. Tr. 2958-9. [

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Reed, R.A. Muench and H.B. Barron Regarding McGuire Nuclear Station Operation Relating To ECCS Termination following Tr.

3045 at pp. 1-3 (" Testimony of Canady Panel II"). Furthor, such log entries must be independently verified. Id. at 3.

If any of the parameters are above the specified criteria, procedures require that ECCS operation be reinitiated. Id.

Applicant testified that in the event of a TMI-type accident at McGuire wherein ECCS operation was prematurely terminated, the operator would have over 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> to reinitiate ECCS operation before generating an amount of hydrogen in excess of a 2% zirconium-water reaction. Id. at 2-3, Tr. 3066-7. 23/

Thus, Applicant concluded that even in the incredible event that ECCS operation was prematurely terminated, it is incredible to further assume that within the two hour period ECCS operation would not be reinitiated prior to generation of hydrogen in excess of a 2% zirconium-water reaction. Id.

at 3.

27. In regard to this issue, the NRC Staff testified as follows:

As demonstrated by the various post TMI actions by the staff including the Short Term Lessons Learned (NUREG-0578), the TMI Action Plan (NUREG-0660), and the TMI Near Term Operating License (NTOL) Requirements (NUREG-0694 and NUREG-0737), the NRC has substantially enhanced its requirements in the areas of operator training, 23/

The Board notes that for comparison 10 CFR $50.44 allows ar a regulatory limit up to a 5% zirconium-water reaction.

See Tr. 3082-3, 4326-7.

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technical competence of the operations staff, and careful development, review and training with respect to operating procedures for coping with emergencies, and off-normal conditions. As a result we believe that the likelihood of an event such as TMI-2 in which a degraded core condition existed for a sufficiently long time to result in substantive hydrogen generation, has been substantially reduced. [NRC Staff Testimony Regarding Hydrogen Control at p. 3.]

Thus, the Staff concluded that in the event of a "small break LOCA [which bounds the TMI accident] it is highly unlikely that substantial amounts of hydrogen will be generated." Id. at p. 1.

28. CESG's case regarding this issue consisted of cross-examination of Applicant's witness panel and presen-tation of five psychologists.

29. CESG's cross-examination focused primarily on the ability of McGuire operators to respond to a TMI-type emergency, the continuing nature of McGuire procedures, the relation between the computer backlog problem encountered during the TMI accident and the McGuire computer, the reasonableness of assuming more than 1 stuck-open PORV in modeling the TMI accident and the possibility and effects of a hydrogen bubble inside the reactor vessel. Responding, Applicant testified that the selection and training of McGuire operators in combination with the use of well written procedures provides assurance that operators will be able to adequately respond to an emergency and will not ,

prematurely terminate ECCS operations (Tr. 2866-7,  !

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2955, 3000-7, 3013, 3022-3, and 4840-41); that procedures 1

are part of the quality assurance program which is ongoing for the life of the plant (Tr. 3070); that the McGuire computer is display oriented and for required information is not susceptible to backlog problems encountered at TMI (Tr.

2884-7); that based on studies it is unreasonable to assume more than one stuck open PORV in attempting to model the TMI accident (Tr. 3093-5); and that a hydrogen bubble, if formed in the reactor vessel, could be detected by several methods and dissipated using the reactor coolant venting system installed in response to the TMI accident (Tr. 3061-3 and 3092-3).

30. CESG's five psychologists focused on a general discussion of the effects of various psychological phenomena on worker performance, i.e., repetitious, boring tasks; information overload; fatigue; stress; cognitive dissonance, group think, risky-shift and reverence for and obedience to established authority; massed and distributive learnir.77 all or none learning and overlearning; and amnesia. Tr. 3624-39, 3835-58, 3977-82. However, CESG's witnesses were unable to relate these phenomena to nuclear plant operations in general or control room operations in specific. ,I d .

Indeed, CESG's witnesses stipulated that they had never conducted an analysis of an operator training program or an operating staff's personnel and organizational structure at any large-scaled nuclear powered electrical generating l

. o facility such as McGuire. Applicant Exhibit 8. To relate such phenomena to nuclear power facilities in general and McGuire in particular, Applicant presented a rebuttal panel  !

of psychologists and training experts (Tr. 4715-9). Appli-cant's witnesses were each well acquainted with the training program and operational staff of nuclear power plants including McGuire.

Professional Qualifications of Dr.

Julien M. Christensen, Dr. Lewis F. Hanes, Dr. Eric F.

Gardner, Mr. Robert M. Koehler, and Mr. Richard J. Marzec following Tr. 4719: Tr. 4720-37. Applicant's witnesses addressed each phenomenon raised by CESG's witnesses and, where applicable, related it to nuclear plant operations in general and McGuire in specific. Tr. 4740-72. Applicant's witnesses concluded that based on their knowledge of nuclear power operations, including operations at McGuire, the phenomena raised by CESG's witnesses would not have a significant adverse impact on operator control room opera-tions at the McGuire station. Id.

31. After reviewing all the evidence on this issue and evaluating the Applicant's response to the Licensing Board's inquiries regarding, inter alia, the subcooling monitor (Tr. 2982-86), the McGuire computer (Tr. 3032-4),

the design and function of the simulator (Tr. 2978-80), the adequacy and accuracy of valve indicators (Tr. 2989-91), the

O 4 i

four termination criteria (Tr. 2987-9), the McGuire steam l generator (Tr. 3085-9), the requalification program (Tr.

2991), and a possible hydrogen bubble in the reactor vessel (Tr. 3092-3), the Licensing Board finds that actions  !

l taken by Applicant, subsequent to the TMI accident, are such that in the event of a TMI-type accident at McGuire the likelihood of ECCS operations being prematurely terminated by the control room operating staff is so remote that such an accident scenario is not credible. 24/ In the unlikely event of premature termination of ECCS, the Board finds that emergency procedures provide reasonable assurance that ECCS will be reinitiated within sufficient time to prevent the generation of hydrogen in excess of 10 CFR $50.44.

The above finding takes recognition of the Commission's guidance in TMI (Restart), supra, 11 NRC at 676, wherein it stated that a " critical issue" in determining the likelihood of an accident entailing the generation of hydrogen in excesslve quintities "would be the likelihood of an operator interfering with ECCS operation."

I l

24/

Applicant would have the Board find at this point that CESG's failure to establish a credible accident scenario resulting in hydrogen generation leading to offsite doses in excess of 10 CFR Part 100, precludes it from further litigating the issue of excessive hydrogen generation and thus its contentions must fail.

TMI (Restart), supra, 11 NRC at 674. The Board will refrain from making such a finding at this point inasmuch as additional evidence has been presented re-garding the McGuire containment response to a TMI-type accident.

l 1

l

32. Evidence was presented regarding the McGuire containment response to a TMI-type accident. This testimony addressed the containment structural capability, containment systems, and the combustion of hydrogen generated in a TMI-type accident at McGuire. In discussing this evidence, the Licensing Board focuses on whether the hydrogen mitiga-tion system installed at McGuire will provide additional safety against containment breach from hydrogen combustion in the extremely remote event of a TMI-type accident at McGuire resulting in excessive hydrogen generation.

Containment Structural Capability

33. Applicant testified that the McGuire contain-ment vessel is a freestanding welded steel structure with a vertical cylinder to which are welded horizontal and verti-cal stiffeners, a hemispherical dome and a flat base.

Applicant Exhibit 5B at 4-4 and 4-7. The vessel is 115 feet in diameter and has an overall height of 171 feet, 3 inches.

Id. The containment pressure vessel pressure boundary has

~

three different thicknesses of steel plate: 1 inch for the lower cylindrical portion near the base, 3/4 inch for the remainder of the cylindrical portion, and 11/16 inch for the dome. Id. at Figure 4.1.1-1. See also, McGuire FSAR Section 3.8.2. Surrounding the containment vessel is a reinforced concrete reactor building composed of a 3 feet thick right cylinder with a 2 feet, 3 inch thick shallow

. o 1

dome. Id. at Section 3.8.1. Between the concrete reactor building and the steel containment vessel is a five foot wide annular space maintained at a slight negative pressure to control and filter radioactive leakage. Id. See also, Section 6.2.

34. As a result of the TMI accident, Applicant under-took an analysis to determine whether McGuire could withstand the pressures associated with a similar type accident. This analysis consisted of:

a structural evaluation of the pressure boundary of the containment vessel to determine the location of minimum strength when loaded with an axisymmetric and quasista-tic uniform internal pressure. The results of this evaluation demonstrated that the region of minimum strength occurred in the cylindrical portion of the shell and was associated with general yielding of the 3/4 inch shell plate / ring stiffener configuration.

The containment was analy=ed to determine its ultimate capacity using a finite element model of the full containment shell. The model was constructed of axisymmetric curved shell elements and analyzed using the MARC computer program. Both geometric and material non-linearities were accounted for in the analysis procedures. The actual containment functional capabil-ity was established using the collapse load criteria of the American Society of Mechanical Engineers Boiler and Pressure Vessel Code,Section III, Division I, Appendix II. [ Testimony of R.B. Priory Regarding Containment Structural Integrity And Response To Licensing Board Questions following Tr. 3654 at p. 1 (" Testimony of Priory")].

For a detailed description of the containment and the above described analysis, see Applicant's Exhibit SB Section

4.0. On the basis of his analysis, Mr. Priory concluded l

. o 9

that the functional capability of the containment pressure boundary is conservatively estimated to equal 67.5 psig.

Testimony of Priory at p. 2. Applicant also presented an independently conducted analysis of R.S. Orr. Testimony of R.S. Orr Regarding The McGuire Containment Structural Integrity following Tr. 3654 (" Testimony of Orr"). Mr.

Orr's evaluation consisted of:

an analysis of a finite element model of one quarter of a panel bounded by longitudinal and meridional stif-feners. Boundary conditions were imposed on the model to account for symmetry. The nonlinear, large displace-ment analysis was conducted using the ANSYS computer program using shell elements. Material behavior was assumed to be elastic-perfectly plastic with yielding based on a Von Mises yield criterion. Loading was assumed to be quasistatic uniform internal pressure.

Analyses were performed in a series of load steps increasing from 0 up to a maximum of 68 psig. [Testi-mony of Orr at p. 1].

On the basis of this analysis, Mr. Orr concluded that the functional capability of the critical panel considered in the analysis would be reached at a limit of 68 psig. Id. at

p. 2. Applicant testified that at this pressure there would be additional leakage through identified leakage paths, but that such leakage would not result in offsite doses in excess of 10 CFR Part 100 limits. Tr. 3757-8. Further, Applicant testified that the ultimate capability of the containment vessel would be approximately 80-85 psig. Tr.

3748-9.

9

35. The NRC Staff testified that it had also con-ducted an analysis of the capability of the McGuire contain-ment and had determined that the mean value for the ultimate strength of the containment shell (i.e., the leak-tight pressure) was 84 psig with a standard deviation of 12 psig. 25/

Staff Testimony Begarding Hydrogen Control at p. 28, and Tr. 4893. However, at this pressure, large deformation of the containment vessel (on the order of 4-5 inches) may be present. Staff Testimony Regarding Hydrogen Control at

p. 28 and Tr. 4906. Such deformation may result in leakage probably caused by a small crack around a penetration. Tr.

4906. Therefore, the Staff subtracted from this mean value three standard deviations to define a lower bound pressure capacity of 48 psig at which design leak tightness is assured. Staff Testimony Regarding Hydrogen Control at p. 28.

36. The Staff testified that assuming the McGuire containment was pressurized to 48 psig, the probability of failure was 4.1 X 10-5 Staff Testimony Regarding Hydrogen Control at p. 32 and Tr. 4894 and 4942-3. Assuming that the hypothetical event causing the pressure had an occurrence

--25/ It should be noted that the Staff analysis reports a McGuire containment capacity up to 120 psig. Tr.

3706-8.

l probability of 1 X 10-6 26/ the overall probability of

, a failure of containment at 48 psig was 4 X 10-11 Tr.

4944. Staff also testified that assuming that an event resulting in an internal pressure of 67.5 psig had a proba-bility of 10-6, the resulting probability of failure of containment would be on the order of 10 10-8 Tr.

4945. The Staff testified that its analysis correlates reasonably well with the testimony presented by Applicant's witnesses. Staff Testimony Regarding Hydrogen Control at p.

29; Tr. 4962.

37. CESG's case regarding this issue consisted of the cross-examination of Applicant's and Staff witnesses and the testimony of Mr. Joe E. Lanford. CESG's cross-examination regarding containment capability focused on inter alia, the consideration of penetrations on the functional capability, the applicability of an R&D Associates study to M:Guire, the possible propagations of defects, the lack of test i ng of the containment vessel at 67.5 psig and the differences between the Staff's analysis resulting in 84 psig and Applicant's

--26/ Intervenor Exhibit 61 reflects various acci a r9nge of probability of occurrence of 10 gentsto with 10- . Included in this group is the S2D sequenc which has a probability of occurrence of 6 x 10-g .

As noted in note 38 infra, the S2D sequence has been referenced in Applicant's testimony. However, Applicant has stressed that the S2D sequence is not the TMI accident, nor is it to be viewed as credible. Tr.

3373-5, 3382-3, 4065-6, 4999-5001, see also note 38, infra. l

1 i

analysis resulting in 67.5 psig. Testimony in response indicates that penetrations were not the limiting item regarding functional capability (Tr, 3657-64); that the R &

D study was not applicable because it was based upon minimum procurement specification strength proprieties and did not view the combined effect of circumferential and longitudinal stiffeners (Tr. 3752-3, 4914); that the McGuire containment was designed to avoid the propagation of defects (Tr.

3692-3, 3717); that the lack of testing did not affect Applicant's testimony or conclusions (Tr. 3757) and the major difference in the Applicant's and Staff's analyses was that the Staff used an analysis which employed actual mean values for various analysis input parameters, whereas Applicant, essentially took the actual mean values and reduced them so as to obtain a design margin. Tr. 3672, 3753-6. 27/

38. CESG presented testimony of Joe E. Lanford, a structural engineer and former Duke Power Company 28/

27/

Inasmuch as Applicant provided design margin in its selection of input parameters, it was unnecessary to apply a standard deviation to its functional capability value of 67.5 psig. Tr. 3669-70. As noted, due to its use of means values, the Staff reduced its mean value of the functional capability of the containment shell by 3 standard deviations so as to assure leak tightness. Staff Testimony Regarding Hydrogen Control ,

'at p. 28. l

--28/ Mr. Lanford stated that his statement of professional' qualifications filed in this proceeding was in error in that he was not a " senior structural engineer" at Duke Power Company. Tr. 4690.

employee. Tr. 3826. Four, five, or six years ago during a visit to the McGuire facility, Mr. Lanford alleged that somewhere on one of the containment structures excessive grinding around a weld caused a gouge in the base metal of about one-eighth of an inch. Tr. 3827-31. Mr. Lanford testified that such defect, if not taken into consideration in calculating containment capability, would invalidate any conclusions. Tr. 3832 3. Mr. Lanford stated that he wrote a report on such weld but was not aware of what corrective action was taken, if any. Tr. 3830.

39. On cross-examination, Mr. Lanford stated that he was not a qualified welder, weld inspector or radiographer.

(Tr. 4679, 4687-8, 4711); that he was not stationed at the McGuire site (Tr. 4678); that he did not work on the containment vessel or liner plate (Tr. 4695); that he did not remember in which unit the alleged gouge appeared (Tr.

4701-2); that he did not recall the location of the alleged defect (Tr. 4699-4700); that he did not know whether the alleged gouge reduced the thickness of the containment shell below minimum specified levels (Tr. 4703); and that he was uncertain as to whether a radiograph would detect the alleged defect (Tr. 4704-5).

40. In response to Mr. Lanford, Applicant presented a rebuttal panel consisting of Messrs L.R. Davison and G. j Grier, both of whom are Professional Engineers with many j years of experience in the area of weld'ing, and associated f

. o inspections at Duke's Oconee Nuclear Station and the McGuire Nuclear Station. Professional Qualifications of Larry R.

Davison and George Grier following Tr. 4845. Applicant's witnesses testified that to become a qualified welding inspector requires two years training and experience, and successful completion of a written and practical examination.

Tr. 4848-9. Applicant testified that after completion of grinding a butt weld, every weld must be visually inspected by a welding inspector and radiographed and the results read by two independent inspectors. Tr. 4847-8 and 4851-2. To assure that every weld is so inspected, quality assurance records are maintained on every weld and signatures for the appropriate inspections are required. Tr. 4852. Every weld

, on the McGuire containment has with it an associated quality assurance record indicating such inspection. Tr. 4847-52.

With regard to a visual inspection, the inspector uses an instrument which detects changes in the metal to 1/32 of an inch. Tr. 4859. With regard to the inspection of a radio-graph, changes in metal up to 15/1000 of an inch would be detected. Tr. 4861. Applicant testified that excessive grinding as described by Mr. Lanford would have been detected in both the visual and radiography inspections and would have been repaired. Tr. 4850-2.

41. The Staff also presented rebuttal testimony in the person of Alan R. Herdt, a registered professional metallur-gical engineer with 20 years experience in methods of

l 1

I welding. Statement of Qualifications of Alan R. Herdt following Tr. 4968. For the period in question, Mr. Herdt ,

l performed welding inspections at the McGuire, facility as a j member of the Atomic Energy Commission Staff.. Tr. 4969.

Mr. Herdt described the nature of construction inspection activities conducted by the Staff (Tr. 4969-70) with specific reference to containment welding (Tr. 4971). He stated that inspection includes magnetic particles inspection, liquid penetrant inspection, visual inspection and radiography.

Tr. 4971-2. Mr. Herdt testified that a one-eighth inch gouge such as described by Mr.-Lanford should have been detected and remedied in the course of the Applicant's inspection program. Tr. 4972, 4981-2. In conclusion, Mr.

Herdt testified that the Staff has not discovered any defects in the steel containment liner at McGuire. Tr.

4973. In addition, Staff testified that gouges in the containment up to 1/8 inch deep and several inches long would have an insignificant effect on calculations regarding the containment capability. Tr. 4895.

42. By Memorandum and Order of January 27, 1981, the i Licensing Board requested that all parties respond +.o four specific questions regarding the calculations involving i containment capability. Specifically, the Licensing Board's l

l concern was the difference in the reported 15 psig " design

1 l

pressure" of the McGuire containment and the higher contain-ment capability reported in testimony of both the Staff and j Applicant. The Staff and Applicant responded. Staff Test-imony Regarding Hydrogen Control at pp. 31-32 and Testimony l 1

of Priory at pp. 2-5. As reflected in such testimony, it is clear that the 15 psig design pressure represents only one of the service loading conditions present in the load combinations under consideration. Testimony of Priory at p.

3. The objective of the analyses contained in Applicant and Staff testimony was to determine the functional capability of the containment vessel to withstand internal pressure.

Id. at 1-3 and Staff Testimony Regarding Hydrogen Control at

p. 31. These determinations are not intended to replace the original " design pressure" with a new value 29/ but,to establish a realistic and conservative estimate 30/ of the full capability of the structure to withstand internal pressure and remain functional. Id.

43. After viewing all the evidence on this issue and evaluating Applicant's and Staff's responses to the Licensing 29/

The record reflects that in the early 1970's (i.e.,

during the initial design phase) a functional capability analysis was not performed; if it had been, the result would have been 67.5 psig. Tr. 3749.

30/

Applicant stated that the assumptions employed in its analysis are sufficiently conservative to assure the result underestimates the functional capability of the containment vessel. Testimony of Priory at p. 5.

These conservatisms are also set forth in the record.

Id. at p. 4; see also Tr. 3669-71, 3715-9.

N, Board's inquiries regarding, inter alia, the von Mises and Tresca criterion related to assumptions in yield analysis (Tr. 3731-3), explanation of terms (Tr. 3746-9), dynamic and quasi-static loading assumptions (Tr. 3734-7, 4955-62),

critical panel determinations (Tr. 3737-9), relationship be-tween design pressure and functional capability (Tr. 3674-6, 3742-4, 3762, 4946-50), reliability and probabilistic concepts (Tr. 4951-4955), material fabrication tolerances 1

(Tr. 4953-4), the relationship between Applicant and Staff's calculations (Tr. 4962), the actions taken by Mr. Lanford regarding his alleged observations of faulty welding (Tr.

4705-8), NRC inspection process regarding welding (Tr.

4865-67), and modifications in Applicant's quality assurance program (Tr. 4867-68), the Licensing Board finds that there is reasonable assurance that the McGuire containment can withstand an internal pressure of 67.5 psig without leakage of such magnitude that offsite doses exceed 10 CFR Part 100 limits.

Containment Systems

44. Applicant testified that systems within the containment vessel that mitigate the effects of excessive hydrogen generation include the ice condenser syste:n, containment air return system, hydrogen skimmer system, containment spray system and the hydrogen mitigation system.

Testimony of David L. Canup II Regarding McGuire Containment Systems following Tr. 3488 (" Testimony of Canup"), Testimony

of William H. Rasin Regarding The Hydrogen Mitigation System following Tr. 3488 (" Testimony of Rasin"), and Applicant Exhibits SB Section 3, and SC.

45. The containment vessel at McGuire is divided into three major volumes.: the lower containment which houses the reactor coolant system, the ice condenser designed to absorb thermal energy in the event of a loss-of-coolant accident, and the upper containment. Testimony of Canup at p. 1.

46. Associated with the ice condenser are three sets of insulated doors located, respectively, along the lower crane wall, in the intermediate deck, and in the top deck.

Id. at p. 2. If lower containment pressure exceeds ice condenser pressure by more than one pound per square foot, as the result of a loss-of-coolant accident, the lower inlet doors will swing open and allow the evolved steam to flow into the lower plenum of the ice condenser. Id. The steam will condense on the ice and chilled structures; but air will pass through the ice bed and open the intermediate deck doors, venting to the upper plenum of the ice condenser, and subsequently the top deck doors, venting to the upper containment. Id. For a complete description, see McGuire FSAR Section 6.2.2

47. Regarding the containment air return system, Applicant testified as follows:

l l The containment air return system, a safety grade system, contains redundant air return fans to return

air from the upper containment into the lower contain-ment. Each fan has a capacity of 30,000 cfm.

Both fans are automatically started approximately 10 minutes after containment pressure reaches three psig.

They may also be started manually by the operator. The fans blow air from the upper containment to the lower containment, thereby returning the air which was displaced by the primary system blowdown to the lower containment. The fans operate continuously after actuation, circulating air through the containment volume. [ Testimony of Canup at p. 2. See also Tr. 3502-3, 3593-4, 3607 3 For a complete description of the containment air return system, see McGuire FSAR Section 6.6.

48. Regarding the hydrogen skimmer system, Applicant 4

testified as follows:

The function of this safety grade system is to prevent the accumulation of hydrogen in dead-ended volumes within the McGuire containment following a loss-of-coolant accident. This system continuously draws air out of these areas. Redundant hydrogen skimmer fans are provided for this purpose. The hydrogen skimmer fans are automatically started approximately 10 minutes after containment pressure reaches 3 psig. The hydrogen skimmer system may also be started manually by the operator. Each hydrogen skimmer fan has a capacity of 3,000 cfm. [ Testimony of Canup at p. 2. See also Tr. 3519-21, 3594 3 For a complete description of the hydrogen skimmer system, see McGuire FSAR Section 6.6.

49. Regarding the containment spray system, Applicant testified as follows:

The primary purpose of the containment spray system, a safety grade system, is to continuously spray cool water into the containment atmosphere when appropriate to remove thermal energy released due to an accident in the containment, thus reducing the resultant contain-ment pressure rise.

i l

l

, . I 38 - l The containment spray system consists of redundant spray pumps and redundant spray heat exchangers. The spray headers are located in the upper containment dome.

The containment spray system is actuated when the pressure in containment reaches 3 psig. The spray system can also be actuated manually from the control room. [ Testimony of Canup at p. 3. See also Tr.

3187-9, 3501-2, 3521-30, 3563-4 3 For a complete description of the containment spray system, see McGuire FSAR Section 6.5.

50. Applicant testified that during the TMI accident hydrogen released into containment was ignited by random, existing sources. Testimony of Rasin at p. 1. Thus, it is reasonable to assume that in the remote event of a similar situation inside the McGuire containm7nt, hydrogen at flammable concentrations would also be ignited by random sources. Id.; Tr. 3285-6, 3503-4. However, to provide additional sources of ignition within the containment and to further assure that hydrogen inside containment would be ignited, Applicant installed the hydrogen mitigation system.

Testimony of Rasin at p. 1.

51. The hydrogen mitigation system consists of 62 glow plug igniter assemblies (46 in lower containment, 8 in the ice condenser upper plenum, and 8 in upper containment) located in 31 distinct areas of the containment vessel. Id.

See also, Tr. 3309-10, 3573-6. Each igniter assembly consists ,

i of (1) a glow plug thermal element which shortly after l activation reaches temperatures which are adequate to l

7 reliably ignite flammable mixtures of hydrogen / steam / air (i.e., 1700-1800*F) at lean concentrations, and (2) a control power transformer. Applicant Exhibit SB at 3-2, Tr. 3608. The non-thermal portion of the glow plug and the transformer are mounted in a sealed box which employs heat shields to limit temperature rise inside the box and a drip shield to reduce direct moisture impingement on the thermal element. Applicant Exhibit 5B at 3-2.

52. The igniters are powered from the emergency lighting power system which has normal and alternative AC power supply from offsite sources. Id. at 3-2 and 3-3. In the event of a loss of offsite power, the igniters will be powered from the emergency diesel generators. Id. Proce-dures require that the igniters be manually activated by the operator upon receipt of a containment isolation signal which indicates that containment pressure has reached 3 psig. Tr. 3341-3, 3496-500. 31/

53. Applicant testified that such igniters had been tested under conditions designed to present significar.t environmental challenges to the effectiveness of the igniter system, and similar to that which may be encountered in the event of excessive hydrogen generation at McGuire. Testi-mony of Rasin at p. 2 and Applicant Exhibits SB at Section 3 31/

Applicant testified that a LOCA, a prerequisite to excessive hydrogen generation, would give rise to pressures in excess of 3 psig thereby actuating the containment isolation signal. Tr. 3587.

1 and SC, Tr. 3174-8, 3280-1. Applicant's evidence demon-strates that the hydrogen igniters which have been installed at McGuire can effectively initiate a hydrogen burn at volumetric hydrogen concentrations of 5 percent and higher.

Applicant Exhibit SC at 5-4.

54. In the event of an accident resulting in the release of hydrogen in excess of the amount specified in 10 CFR

$50.44 these igniters will burn the released hydrogen at. low concentrations, thereby preventing the burning or detonation of a large concentration of hydrogen. Id. and Testimony of Rasin at p. 2. 32/

55. The NRC Staff had previously reviewed the exist-ing systems in the McGuire plant including the ice condenser system, hydrogen skimmer system, containment air return system and containment spray system and concluded that such systems comply with, and will operate in conformity with, applicable Commission rules and regulations. Staff Exhibit I at p. I-2. With regard to the hydrogen mitigation system the NRC Staff reviewed Applicant's proposed system and the results of tests conducted by Applicant and concluded that the glow plug igniters will serve their intended function of initiation of hydrogen combustion. Staff Testimony Regarding

--32/ With regard to the continuous burn in the ice con-denser, the evidence reflects that the ice condenser will not be affected. Tr. 3316.  ;

i l

l l

Hydrogen Control Measures at pp. 9-14. In addition, the i

NRC, through the Lawrence Livermore Laboratory, conducted tests of the igniters which " confirmed the ability of'the proposed Duke igniters to ignite gas mixtures over a range of conditions." Id. at p. 15. During the 43 test runs involved, the igniters never failed to initiate combustion for any conditions up to a 40% steam fraction. Id. How-ever, the Staff reported on the results of tests at steam fractions over 40% as follows:

Several tests were also run with a nominal steam fraction of 50%. These tests were performed to determine what size steam fractions would be neces-sary to prevent ignition of the mixture. In all the tests with a 50% steam fraction we were unable to initiate combustion. This steam concentration which was observed to effectively inert the vessel atmosphere also approximates the values quoted in the published literature. Two tests which began at nominal steam concentrations of 50%, with no initial combustion, were allowed to continue with the steam fraction being gradually reduced by condensation on the vessel wall.

Even though the steam fraction was eventually reduced to levels where combustion should have occurred, no substantial pressure increase, as a result of hydrogen burning, was recorded. We have been unable at this time to conclusively resolve why a pronounced burn did not occur and plan to continue our investigation of this matter. Because the initial steam concentration in the tests was higher than the calculated steam concentration just prior to when hydrogen burning occurs in the McGuire base case analysis, we see no immediate cause to consider these particular tests results as a bases for rejection of the Duko EHM system as an interim solution to hydrogen control for degraded core accidents.

The Staff is planning to continue the Livermore tests for several months to investigate the ef fects of containment spray operation on igniter performance and

to further study hydrogen combustion in steam environ-ments. (Id. at 16]. 33/

56. CESG cross-examination regarding containment systems focused on potential icing of the lower ice con-denser doors, the adequacy of the water supply for the containment spray system, the adequacy of ice in the ice condenser, the viability and consideration of other miti-gation systems and the possible inerting of the lower containment due to excessive steam concentrations. Testimony in response reflected that to date there had been no problems with icing of the ice condenser doors at McGuire (Tr. 3595) and, in any event, during operations such doors would be checked every 7 days for operability 34/ (Tr. 3534-6); that the containment spray system has a continuous source of water from the containment sump which employs screens to prevent blockage (Tr. 3521-30 and 3533); that other mitiga-tion systems, including nitrogen inerting, halon suppression, and carbon dioxide inerting were discussed and shown not to be currently preferable (Tr. 3541-6, 3566-73, 3602-3); that an analysis of a TMI-type accident clearly demonstrates that 33/

~~

See Tr. 4431-2, wherein the Staff addressed the R & D Associates review of the Lawrence Livermore Laboratory anomolous tests. The R & D Associates review did not cause the Staff to recant their above position regarding the Lawrence Livermore tests. See Tr. 4497-4504.

34/

~~

The Licensing Board notes that this issue was raised by CESG during the Construction Permit proceeding for l

McGuire and thoroughly explored by the Atomic Safety j and Licensing Board. 6 AEC 92, 102-3 (1973).

r ,

l even after the transient is completed there is an adequate supply of ice remaining 35/ (Applicant Exhibit 5B at Table 6); and that steam did not materially affect hydrogen combustion until the steam fraction reaches approximately i C0% and steam inerting did not occur until a higher steam firaction was reached. 36/ (Testimony of William Rasin, David Goeser, Bela Karolovitz, Bernard Lewis and Edward McHale Regarding Hydrogen Generation and Ignition following Tr. 3144 at p. 8). See also Tr. 3210, 4153-6, 4306. For a discussion of the effects of steam inerting of the lower

! containment, see pp. 57-9, infra.

57. After reviewing all the evidence on this issue and evaluating Applicant's and Staff's responses to the Licensing Board's inquiries regarding, inter alia, testing and maintenance of the glow plug igniters (Tr. 3596-7, 3608-9), existing ignition sources inside the McGuire contain-ment and the effect of water on such sources (Tr. 3597-3602),

l

--35/ In any event, the Licensing Board notes evidence which clearly establishes that even without ice at the conclusion of the transient, containment pressures vould net be excessive. Staff Testimony Regarding Hydrogen Control Measures at p. 24 and 27.

36/

~~

Applicant testified that the results of steam inert-ing at steam fractions between 40 and 50% as reported in the Lawrence Livermore experiments performed for the NRC Staff were not reliable in that such steam fractions failed to take into considertion the additional effect of condensed water droplets which occurred due to the cold walls of the very small test vessel. (Tr. 3213-4).

a e inerting the containment with nitrogen or CO 2

(Tr.

3602-3), the creation of a vacuum inside containment (Tr.

3604-6), and operation of the ice condenser doors (Tr.

3606-7), the Licensing Board finds that (1) there is reason-able assurance that the hydrogen skimmer system, containment air return system, ice condenser system and containment spray system are designed and constructed in accordance with appropriate regulations for such safety grade systems and will operate as designed when called upon, and (2) that there is reasonable assurance that flammable mixtures of hydrogen / steam / air in the McGuire containment will be ignited at lean concentrations by either random ignition sources or the hydrogen mitigation system. 37/

37/

~~

The Licensing Board is cognizant of the Commission's September 17, 1980 decision authorizing full power operation of Tennessee Valley Authority's ("TVA")

Sequoyah Nuclear Plant, an ice condenser facility similar to McGuire. Tr. 3403. Therein, conditions were imposed regarding the hydrogen mitigation system:

(a) By January 31, 1981, TVA shall by testing and analysis show to the satisfaction of the NRC Staff that an interim hydrogen control system will provide with reasonable assurance protection against breach l

of containment in the event that a substantial l quantity of hydrogen is generated.

(b) For operation of the facility beyond January 31, 1982, the Commission must confirm that an adequate l hydrogen control system for the plant is installed l and will perform its intended function in a manner j that provides adequate safety margins.

[ footnote continued on next page].

. e 1

Combustion Of Hydrogen Generated In a TMI-Type Accident At McGuire

58. Applicant presented a panel of eminently qualified experts in the area of hydrogen and hydrogen combustion phenomena. The panel included Dr. Bernard Lewis who has been involved in this area for over 50 years and is the author of two textbooks used throughout the world on "Com-bustion, Flames and Explosions of Gases" (Professional Qualifications of Dr. Bernard Lewis following Tr. 3144); Dr.

Edward T. McHale who has been involved in this area for over 20 years and is the author of numerous publications regarding hydrogen and combustion (Professional Qualifications of Dr.

Edward T. McHale following Tr. 3144); and Mr. Bela Karlovitz who has been involved in this area for over 35 years during

[ footnote continued from previous page].

(c) During the interim period of operation, TVA shall continue a research program on hydrogen control measures and the effecte of hydrogen burns on safety functions and shall submit to the NRC quarterly reports on that research program.

See Staff Testimony Regarding Hydrogen Contro] at pp.

8-9. In January, 1981, both the NRC Staff and the Commission determined that condition one had been satisfied. Id.

See also Tr. 4060, 4365. The Staff has indicated that the remaining two conditions should be made applicable to McGuire. Staf f testimony Regard-ing Hydrogen Control at pp. 8-9, Tr. 4060, 4365, 4442-3.

The Licensing Board is also cognizant of Applicant's confirmatory research efforts regarding the hydrogen  !

mitigation system. Tr. 3312-4, 4493-4. i l

1

)

which time he, inter alia, developed the theory of turbulent flame propagation and originated the concept of flame

- stretch and theory of flame generated turbulence (Professional Qualifications of Bela Karlovitz following Tr. 3144).

Significantly, all three experts have been actively involved with investigations of hydrogen combustion specifically at nuclear power facilities. (Tr. 3162-66). In, addition, they have thoroughly analyzed the McGuire containment structure drawings and design details and have physically examined the inside of the McGuire containment vessel itself to include the ice condenser section. Testimony of William Rasin, David Goeser, Bela Karlovitz, Bernard Lewis and Edward McHale Regarding Hydrogen Generation and Ignition following Tr. 3144 at p. 1 (" Testimony of Lewis Panel"). With regard to the distribution of hydrogen in the McGuire containment assuming a hypothetical TMI-type occident resulting in the generation of hydrogen, Applicant's witnesses testified as follows:

In such a situation, the pressure in the primary coolant system would cause the resulting hydrogen and steam mixture exiting the break to enter the lower containment in the form of a high velocity, turbulent jet. Such a jet entrains the surrounding medium by turbulent mixing. The length of the jet required for effective mixing will be small as compared with the dimensions of the lower McGuire containment. Thus, mixing of the hydrogen-steam jet with the air in the lower containment will be rapid and complete.

In addition to jet entrainment mixing, turbulence in the lower containment created by the air-return fans accelerates rapid mixing of hydrogen with the atmo-sphere in the lower containement.

1 Some of the hydrogen-steam-air mixture will flow into the so-called " dead-ended" chambers. Due to flow and turbulence in these chambers, mixing will be rapid and complete. Since there are exit paths, the pressure will force recirculation of this mixture. This assures that the hydrogen concentrations in these volumes do not vary significantly from that of the remainder of the lower containment.  !

From the lower containment, the hydrogen steam-air mixture will pass through the ice condenser where steam is removed ~and only a hydrogen-air mixture will emerge at the top. The lattIer mixture emerging from the ice condenser passes into the upper containment where it mixes turbulently with the air in the upper contain-ment. This mixing is aided by the water spray from the containment spray system. The two containment air return fans will circulate such hydrogen-air mixtures from the upper containment back into the lower contain-ment. It should be noted that these fans each have a 30,000 CFM capacity and together can6 turn around the total cor.tainment volume of 1.2 x 10 cubic feet in approximately 20 minutes. Thus, the fans enhance the rapid mixing of hydrogen. Testimony of Lewis Panel at pp. 9-10.

59. Further, Applicant's witnesses testified as follows as to the ignition and burning sequence which would occur should a TMI-type accident hypothetically occur at McGuire:

The ignition and burning of hydrogen generated in a TMI-type accident at McGuire will occur by: (a) a continuous burn at the top of the ice condensers; (b) a series of burns initiated in the lower contain-ment; or (c) a combination of (a) and (b) above.

It should be noted that of these three burning se-quences, the successive burns of hydrogen initiated in the lower containment (case (b) above) will result in the highest peak pressures.

Should a hypothetical TMI-type accident occur at McGuire, the resulting hydrogen will be evenly mixed l

inside the lower containment in a hydrogen-steam-air j

atmosphere. The mixture will pass from the lower i containment through the ice condensers where the steam i

I 1

is removed and emerge from the ice condensers as a hydrogen-air mixture. As the concentration of hydrogen in the hydrogen-steam-air mixture in the lower contain-ment increases due to hydrogen production inside the core and venting of such hydrogen into the lower containment, the concentration of hydrogen in the hydrogen-air mixture exiting the ice condenser will correspondingly increase.

If this concentration reaches approximately 8.5%

hydrogen at the exit of the ice condenser (the upper plenum region) the distributed ignition system will-cause such hydrogen to ignite and burn (case (a)).

Burning will continue until the concentration of hydrogen exiting the ice condenser falls below approx-imately 8.5%. The air return fans will continue to recirculate the combustion products from the upper containment to the lower containment. Therefore, all or most of the hydrogen would be burned at the top of the ice condenser with only small pressure development for the McGuire containment.

If the hydrogen-steam-air mixture in the lower con-tainment becomes flammable, the distributed ignition system will cause ignition and a propagating burn will develop (case (b)). Multiple burns will ensue....

[ Testimony of Lewis Panel at pp. 10-11].

60. Applicant's witnesses testified that the Case (a) scenario (i.e., continuous burn of hydrogen in the ice condenser), is the likely scenario which would occur and the pressure rise in containment resulting therefrom would only be a few psi. (Tr. 3353-7). Applicant testified that of the three scenarios, the peak pressure in contain-ment would result from a Case (b) scenario (i.e., multiple burns of hydrogen in the lower containment). Testimony of the Lewis Panel at p. 10. Applicant analyzed such a l c i

l t

case 38/ using the CLASIX computer code 39/ and testified as follows:

An analysis has been performed to determine the pres-sures that would occur if the events which resulted in hydrogen production at TMI-2 were hypothetically assumed to occur at McGuire.

Under this hypothetical condition, hydrogen would be produced by the following chemical reaction:

Zr + 2H O >

2 ZrO2 + 2H2 + heat The total amount of zirconium contained in the fuel cladding is approximately 45,000 lbm.

The interconnected volumes of the McGuire containment were analyzed including the lower containment, ice condenser, upper containment and dead-ended volumes.

Further, the effects of the ice condenser, containment sprays and air return fans were included. The contain-  ;

ment sprays, air return fans, and hydrogen skimmer fans will be in operation well before any hydrogen  !

generation since they are actuated by a 3 psig lower  ;

i 38/ The actual accident analyzed by Applicant, a small- ,

break loss-of-coolant accident assuming f ailure of . the .

ECCS and a 75-80% zirconium-water reaction, is termed  ;

the S2D accident. Tr. 3373-5 and 3382-3. Such acci-dent is clearly not the TMI accident and was selected I only because it tended to represent the TMI accident in  !

mass and energy release rates and the code for the -

accident was readily available. Id. See also, Tr.

4065-6, 4999-5001. The actual conditions assumed for -

this case (b) scenario base case accident are described

• in Testimony of Lewis Panel at pp. 2-3 and App.1 cant  ;

Exhibits SA at 2-2 through 2-5 and SB at Table 6, -

l Accident Scenario JVD12. .

t 39/ CLASIX is a multi-compartment containment code which calculates pressure and temperature response for the individual compartments. The only passive heat sink ,

modeled by CLASIX is the ice bed. Applicant Exhibit 5A at 1-5; see also, Tr. 3274-80. The mass and energy ,

releases from the break were based on calculations by '

[

Battelle Memorial Institute at Columbus using the MARCH code. Applicant Exhibit 5A at 2-3; Tr. 3177-8, 3302. ,

While neither of these codes have been verified, they (

have been compared to approved codes and the results r have provided an acceptable level of confidence.  !

l Applicant Exhibit SB at 2-21, Tr. 3276-7, 4179. i i

I [

containment pressure which will be reached on the initial blowdown early in the accident. The transient pressure, flow and gas concentrations were calculated.

The amount of hydrogen assumed to be released into the i lower containment exceeded the 50 percent metal-water reaction reported in the TMI-2 event.

Ignition of the hydrogen was assumed to occur if the concentration reached 10 volume percent. This hydrogen ignition then resulted in complete burning with all energy absorbed in the atmosphere. No credit was included for energy losses to passive structures.

Since ignition would probably occur at lower concen-trations than the 10% used, this analysis results in higher calculated pressures than would actually be expected in the volume experiencing the burn. Energy losses to the passive structures would further reduce the pressure.

Hydrogen builds up in the lower containment at the start of the transient until 10 volume percent is reached. After ignition, the pressure is relieved by flow out of the lower containment through the ice condenser. Energy is extracted in the ice condenser leading to very small pressure increases in the upper containment. Hydrogen builds up again in the lower containme nt, and air is circulated by the air return

fans leading to another ignition. This process repeats until the hydogen concentration can no longer reach the 10 volume percent. No credit was taken for con-tinous burning in the upper plenum of the ice condenser as would be the case in a case (c) ignition and burning sequence... The results of this analysis show that if multiple hydrogen burns occur such as reported in a case (b) sequence... the peak pressure is less than 16 psig. [ Testimony of Lewis 7anel at pp. 2-3]. 40/

61. With regard to the effect on essential equipment 41/

of the ignition and burning of hydrogen in the event of a I

40/

Applicant testified that the analysis conducted was extremely conservative in that, inter alia, it did not l include the effect of structural heat sinks (Tr. 3265 as corrected by.3363) and combustion of hydrogen was artifically suppressed until 10% hydrogen concentrations were reached (Testimony of Lewis Panel at p. 2).

41/ See Testimony of Lewis Panel at p. 12 wherein the essential equipment is described. j 4

g , , - - - --

TMI-type accident, Applicant testified as follows:

Based upon the range of temperatures this equipment can survive and based upon a consideration of the temper-ature of the flame front, its speed and duration, the heat transfer from the hot burned gases, the time for the hot burned products to return to ambient temper-atures, and the total heat energy available, it is concluded that the essential equipment needed for the safe shutdown of the plant will not be so affected by the combustion of the hydrogen so as to impair its ability to safely perform its intended function.

[ Testimony of Lewis Panel at p. 12. See also, Tr.

3346-7]. .

The bases for Applicant's testimony regarding equipment survivability are experiments conducted by Applicant (Testi-mony of Lewis Panel'at p. 12) and independent calculations performed by Applicant (Tr. 3144-50).

62. The NRC Staff reviewed Applicant's analysis regarding the multiple hydrogen burn scenario (noted above as Case (b)) and concluded that the CLASIX code used by Applicant " adequately predicts the containment transient" of hydrogen combustion at McGuire assuming the mutliple burn scenario. Staff Testimony Regarding Hydrogen Generation at pp. 18-27.

63. The Staff also obtained technical assistance from ,

the Battelle Columbus Laboratory to analyze the containment atmosphere response to the combustion of hydrogen using the MARCH code. Id. at 26-27 Th6 results of the analysis were similar to those calculated by Applicant. Id.

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64. With regard to the issue of equipment surviva-bility the NRC Staff after conducting an independent analy-sis of all relevant equipment and thoroughly reviewing Applicant's analysis, concluded as follows:

Based on our review, we believe that there is suffi-cient basis to conclude that equipment important to maintain containment integrity and important to re-covery from inadequate core cooling conditions will be able to survive the effects of the intentional combus-tion of H 7 at the McGuire facility. [ Testimony of Staff Regarding Reactor And Containment Systems Per-formance Assessment following Tr. 4535 at p. 9. See also Tr. 4538, 4621-3].

65. Thus, after thorough review and independent analysis of Applicant's entire program regarding mitigation of hydrogen generation, the NRC Staff concluded as follows:

The Staff concludes that the EEM [ emergency hydrogen mitigation] system would serve to greatly reduce the consequences of a severely degraded core accident. The Staff also finds that the proposed EHM system will provide, with reasonable assurance, protection against breach of containment in the event that a substantial quantity of hydrogen is generated. In the report dated January 13, 1981, the ACRS concurred with the conclusion that a distributed ignition system will reduce the consequences of a severely degraded core accident. The operation of the igniter system acting in concert with existing heat removal mechanisms in the plant, i.e.,

the ice bed, sprays and passive heat sinks, would sufficiently reduce, for certain accident scenairos, the increase in containment atmosphere pressure result-ing from the burning of hydrogen. The Staff has previously determined that without a reliable ignition system ice condenser plants could tolerate the burning of only that amount of hydrogen that would be released by approximately a 25% zirconium cladding-water reaction. The analyses presented herein which have credited operation of the EHM system have been per-formed for an accident which was allowed to proceed to the point where 80% of the core cladding reacted. This increased containment capability to accomodate hydrogen releases represents a substantial improvement over the design basis capability. The increased capacity of the containment to tolerate the energy addition due to hydrogen burning is a rate dependent phenomenon such

that the proposed EHM system allows for a more con-trolled burning of lean hydrogen mixtures in the containment. Moreover, the actuation of igniters precludes the formation of large volumes of hydrogen gas at a detonable concentration in the event of large hydrogen releases. [ Staff Testimony Regarding Hydrogen Control Measures at 38].

CESG's case regarding this issue consisted of l 66.

cross-examination of Applicant and Staff witnesses. CESG's cross-examination focused upon (1) the effects of loss of various equipment such as containment air return fans on Applicant's analysis, (2) the validity of calculations ,

regarding the issue of equipment survivability, (3) the possibility of detonation of hydrogen in the ice condenser, and (4) the effects of a continuous burn in the ice condenser on polyurethane foam insulation.

i .

67. With regard to CESG's concern over the effect of the loss of containment air return fans, hydrogen skimmer fans and containment sprays on Applicant's calculations, 42/

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--42/ To the extent that CESG is concerned that in Appli-cant Exhibit SB, analyses are conducted assuming various hydrogen concentrations up to 14% and only i partial operation of various systems, Applicant testi- l fled that analyses outside the base case (i.e., JVD12 noted on Table 6 of Applicant Exhibit 5B) are not considered realistic or representative of a potential i scenario. Tr. 3387-9. See also, Tr. 3384-6. Such ,

analyses were performed as sensitivity studies to l determine the effect of parameter variance for the i purpose of making decisions regarding, inter alia, the scope of Applicant's testing program. Id. and Applicant Exhibit 5A pp. 2-2 through 2-9. In any event, in all cases analyzed where hydrogen concentration was assumed to be below 12%, the resulting pressure increases were well below 67.5 psig. Applicant Exhibit SB at Tables 6 <

and 7. With regard to scenarios which assumed hydrogen  ;

concentrations of 12-14%, Applicant testified that such l concentrations would not occur at McGuire. Tr. 3347-8. l

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54 -

Dr. Lewis and Mr. Karlovitz, together, and Dr. McHale separately, conducted independent analyses of the resultant pressure associated with an assumed TMI accident at McGuire with the loss of the above noted equipment. Tr. 3357-8.

Dr. Lewis and Mr. Karlovitz testified that the resulting pressure, assuming an 80% zirconium-water reaction, would be between 25 and 35 psig depending on the initial pressure.

Tr. 3358-9. Dr. McHale, using a different analytical approach, testified that the resulting pressure would reach an equilibrium point of 30 psig where it would remain even assuming a 100% zirconium-water reaction. Tr. 3359-61.

Clearly, the loss of all such redundant, safety grade equipment is well beyond the TMI accident scenario and indeed incredible.

68. CESG's concern regarding the validity of Appli-cant's calculations regarding equipment survivability focused on whether Applicant's calculations applied to multiple burn scenarios and whether temperature profiles reported in Applicant Exhibit 5B were accurate. Applicant testified that the equipment survivability calculations contained " enormous conservatisms" (Tr. 3391) and would apply to closely spaced multiple burn scenarios (Tr. 3425-6).

Further, Applicant testified that the temperature profiles reported in Applicant Exhibit SB were based upon a computer code which did not contain structural heat sinks, and thus such profiles were totally unrepresentative of expected temperatures (Tr. 3426-7).

I

69. The basis for CESG's questions over possible detonation 43/ inside the ice condenser 44/ is a misconception of the configuration of the ice condenser and the testimony of Dr. Marshal Berman, a Staff consultant from Sandia Labar-atories, who voiced concern over the possibility of detona-tion of hydrogen in the upper plenum regions of the ice condenser. 45/ With respect to the configuration of the ice condenser, Intervenor attempted to imply the existence in the ice condenser of narrow confined geometry which would

--43/ In testimony, reference was made to Professor Roger A.

Strehlow's concern over the possibility of transition to detonation in the ice condenser if sdequately high concentrations of hydrogen were present (e.g., Tr.

3412). Applicant testified that concentrations of hydrogen that are present in the ice condenser are far below the concentrations at which transition to detona-tion occurs. Id. In addition, the evidence reflected that Dr. Strehlow's concern is combustion inside small pipes in the ice condenser. Tr. 3405. There are no pipes in the ice condenser. Tr. 3406. Applicant's panel of experts stated that Dr. Strehlow did not understand the configuration inside the ice condenser.

Tr. 3406-7. It should be noted that Dr. Strehlow found that the igniter system will have no negative effects on overall safety., Tr. 3351-3, 3367.

44/

The ' record reflects that local detonation inside the McGuire containment is not possible. Tr. 3347, 3155-6.

45/

Dr. Berman was the "overall editor" of the Sandia Laboratory Draft and Final Reports referenced as CESG Exhibits 40 and 40A, respectively, and authored, inter alia, the section on accident analysis. (Tr. 4042-3). -

The subject of the Sandia Report was, inter alia, the adequacy of the ignitor system at the Tennessee Valley Authority's Sequoyah Nuclear Station. CESG Exhibit 40 at p. 1. Significantly, the Sandia Report supports the adequacy of the igniter system's ability to respond to a TMI-type accident with the exception of the location of igniters in the upper plenum of the ice condenser.

Tr. 4082, 4087, 4101, 4112.

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promote transition to detonation. The testimony reflects that there are no long, narrow confined passageways in the ice condenser; rather the area between the baskets is open, the tops and bottoms of the baskets are open, there are holes along the baskets and that the lattice frame would not confine any substance from flowing through the condenser.

Tr. 3489-94. 46/

70. With respect to Dr. Berman, upon extensive cross-examination, it was clear that he had never visited either the Sequoyah Nuclear Facility or McGuire (Tr. 4215) and was not familiar with the design and construction of the ice condenser at the McGuire facility (Tr. 4216-4232). Further, Dr. Berman testified that he did "not claim to be an expert in combustion" (Tr. 4250) and his conclusions regarding the possibility of detonation in the upper plenum region of the ice condenser were "strongly influenced" by Dr. John Lee, a Sandia consultant (Tr. 4199-200). However, Dr. Berman's contact with Dr. Lea on this issue was very limited. Tr.

4202-12. Further, Dr. Berman stated that he did not know of Dr. Lee's familiarity with the design of ice condenser plants such as Sequoyah and McGuire (Tr. 4212-3) and indeed Dr. Berman stated that Dr. Lee's experience in nuclear reactor safety was limited (Tr. 4239).

46/

-~

CESG also focused upon the possibility of transition to detonation in the ductwork of the air handling units. The testimony reflects that the geometry of these ducts is such that transition to detonation will not occur and that hydrogen concentrations necessary for transition to detonation will not be present. Tr.

3613-7.

57 -

71. With regard to his concerns, Dr. Berman testified that Dr. Lee's experiments regarding stoichiometric concen-trations 47/ of propane in large tubes open at one end with periodic obstacles placed therein resulting in transi-tion to detonation may be applicable to the upper plenum region of the ice condenser. Tr. 4095-7. However, for such transition to detonation to occur, Dr. Berman testified that there must be high concentrations of hydrogen in the upper plenum which he postulates to result from steam inerting of the lower containment. Tr. 4250-2.

72. To respond to Dr. Berman's concerns, Applicant pre-sented Dr. Lewis and Mr. Karlovitz, who after having consulted with Dr. Lee, described the procedures used in his experi-ments. Tr. 5046-5050. Applicant's witnesses testified that the results achieved by Dr. Lee were what would have been predicted in such a situation and involved phenomena to which Dr. Lewis had previously testified. Tr. 5048-9. Dr.

Lewis testified, however, that the open, unconfined geometry of the upper plenum region was such that the results produced by Dr. Lee could not be produced in the upper plenum regions.

Tr. 5050. See also 5057-8. Furthermore, Dr. Lewis testified that if concentrations of hydrogen and steam in the lower compartment began to increase rapidly such that steam l

47/

~~

A stoichiometric mixture of hydrogen and oxygen consists of two moles of hydrogen for every mole of oxygen present. Tr. 4286-7. In air this would be a mixture consisting of approximately 29% hydrogen. Id. The further away from a stoichiometric mixture, the more difficult to achieve transition to detonation. Tr.

4299.

inerting occurred, the'resulting concentration of hydrogen i flowing through the ice condenser would increase correspond-ingly. 48/ Tr. 5051-6, 5102. When the hydrogen / air mixture entering the lower plenum reached flammable concentrations ignition and burning would occur. Id. As the concentration of hydrogen flowing through the ice condenser increased, the flame would settle into the ice condenser at a level where such mixture was just flammable and continue to burn. Id.

j Thus, due to the presence of the igniters in the upper plenum regions there would never be a detonable mixture of high hydro- j gen concentration in the upper plenum region. Id. 49/ 50/ 1

73. The Staff was fully aware of the concerns of Dr. i Berman, but stated that its review of the matters raised did not t

~~48/ This scenario is one raised in the Brookhaven Report  !

(CESG Exhibit 59) and relied on by Dr. Berman to (

establish the inerted conditions in the lower contain-  ;

t ment. Tr. 4089-90,4250-2, 4257. While the Licensing [

Board notes that findings cannot be based on the  ;

Brookhaven Report (Tr. 4663), such Report concluded -

that the distributed ignition system, such as installed at McGuire, effectively mitigated the effects of l hydrogen burns resulting from TMI-type accident scenar- l 4

io (CESG Exhibit 59 at pp. 1-3).  !

49/

It should be noted that Dr. Berman acknowledged that with moderate generation of hydrogen and adequate l mixing, there was very little probability of obtaining }

detonable conditions. Tr. 4285.  !

50/

Applicant testified that even if a mixture of hydrogen ,

in air is within detonable composition range, it is I unlikely that a detonation will result due to the  ;

unconfined conditions and the weak thermal igniters.  ;

Tr. 31S5.

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alter its conclusion that upper plenum igniters should be so located and activated if necessary. Tr. 4111-6, 4368. With specific reference to steam inerting, the Staff testified that inerting of the lower compartment is not expected for

/

the TMI-type of accident. Tr. 4360-1, 4365, 4395-6.

74. With regard to the effects of a continuous hydrogen burn in the ice condenser on the insulating polyurethane foam, Applicant presented a panel consisting of Dr. Lewis,

Mr. Rasin and Dr. Leonard E. Edelman. Dr. Edelman has 4 been involved in the polymer field for 30 years during which time he has issued over 25 patents in polymer chemistry and developed the specifications for the polyurethane foam used in ice condenser nuclear plants. Tr. 5041-3 and Professional Qualifications of Dr. Leonard E. Edelman following Tr. 5042. Regarding this issue, Dr. Lewis testi-fled that assuming a TMI-type accident which resulted in generation of hydrogen and a continuous burn of such hydrogen i in the ice condenser, the flame temperature inside the ice condenser would be theoretically about 1400* F for an 8-1/2%

hydrogen concentration (Tr. 5068); the height of the flame would be at most about 1 centimeter (Tr. 5082); and that within a few feet upward the hot gases would have cooled to about 400-500*F (Tr. 5077). Dr. Edleman testified to the general characteristic of the polyurethane and specific

, o effect of heat on the polyurethane foam. Tr. 5106-5110.

Applicant performed a heat transfer analysis regarding the heat which would be seen by the foam given the flame and hot gas temperature noted by Dr. Lewis. Tr. 5111-5116. 51/

Applicant testified that the resulting effect of such heat would be to volitilize a portion of the foam, but that the increased pressure to containment resulting therefrom would be insignificant. Tr. 5116-5119, 5215-6. Applicant testified that if the foam was not enclosed but totally exposed to oxygen and a flame, it would burn as long as there was sufficient oxygen to support combustion. Tr.

5139-41. However, in the sealed geometrical configuration at McGuire there is little oxygen to support combustion (Tr.

5106-7, 5139) and the foam itself does not generate free oxygen for such support (Tr. 5139). An experiment conducted

' in such a configuration resulted in an inability to sustain combustion even when a large opening was present. Tr.

I 5145-7, 5159-60, 5180, 5222-3. The NRC Staff reviewed Applicant's testimony and concurred in the analysis and conclusions. " Joint Affidavit" of NRC Staff (March 27, 1981).

--51/ Applicant's heat transfer analysis was extremely conservative in that, inter alia, it ignored the presence of ice in the ice condenser (Tr. 5154) l and it assumed a 6 inch flame. (Tr. 5180-3, 5187-92).

?

75. The Licensing Board reviewed the evidence pre-sented on this issue as noted above and evaluated Applicant and Staff responses to Licensing Board inquiries regarding, inter alia, the effect of the hydrogen burn at TMI (Tr.

3368-73), accident scenarios (Tr. 3373-5, 3382-6), the possibility of hydrogen combustion at the exit of the break in the reactor coolant system (Tr. 3375-82), the CLASIX code (Tr. 3387-90, 3396-7), calculations involving equipment survivability (Tr. 3390-95, 3430-3431), the method for dissipating a hydrogen bubble in the reactor vessel (Tr.

3397-8), Dr. Strehlow's Report (Tr. 3400-15), Sandia's concern regarding detonation (Tr. 4096-7, 4272-99, 5087-5090), 52/ instrumentation for measuring hydrogen (Tr.

5092-8), temperature profile in the ice condenser (Tr.

5207-12), and polyurethane foam (Tr. 5212-17).

76. The Licensing Board finds that for a range of accidents resulting in hydrogen generation, including a TMI-type accident, the mitigation system installed at McGuire will provide reasonable assurance that such hydro-gen will be burned at lean mixtures resulting in pressures that are well below the functional capability of the con-tainment vessel.

52/ The Licensing Board notes that the concerns of Sandia, as well as the previously referenced Brookhaven document were taken into account prior to the licensing of Sequoyah in late January, 1981. Tr. 4174.

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IV. Conclusions of Law In an operating license proceeding, the Board is called upon to decide only the issues in controversy among the parties (10 CFR $2.760a and Appendix A to 10 CFR Part 2,

$VIII). In this reopened hearing, the contentions and evidence have placed in issue the general subjects of the credibility of the TMI accident at McGuire and the ability of the McGuire containment to withstand a TMI-type accident.

Based upon the foregoing Findings of Fact which are supported by reliable, probative and substantial evidence as required by the Administrative Procedure Act and the Commis-sion's Rules of Practice, and upon consideration of the entire evidentiary record in this proceeding, the Board, supplementing those Conclusions of Law contained in its April 18, 1979 Initial Decision, makes the following Conclu-sions of Law:

(1) There is reasonable assurance that in the event of a TMI-type accident at McGuire there will not be substantial quantities of hydrogen (in excess of the design basis of 10 CFR $50.44) generated.

(2) There is re'asonable assurance that if substantial quantities of hydrogen (in excess of the design basis of 10 CFR $50.44) are generated as a result of a TMI-type accident at McGuire, such hydrogen will combust and such combustion will not result in containment breach and offsite doses in excess of 10 CFR Part 100 limits.

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(3) there is reasonable assurance that the hydro-gen mitigation system will provide an additional measure of safety. The Board is cognizant of staff testimony concerning ongoing research regard- l ing this matter. The Board understands that Director of Regulation would condition the McGuire license in a manner similar to his action in ,

Tennessee Valley Authority's Sequoyah Nuclear f i

Plant.

i (4) That based upon Conclusions (1), (2), and (3) the Board finds that there is no basis for Inter-venor's Contentions 3 and 4, which are premised i upon the generation of excessive amounts of hydrogen and combustion resulting in containment breach and offsite doses in excess of 10 CFR Part 100.

(5) The NRC Staff has issued Supplement 4 to the McGuire Safety Evaluation Report (Staff Exhibit I) relating to unresolved generic safety issues which is in conformity with the Licensing Board's April 18, 1979 Initial Decision regarding the McGuire facility.

. V. Order WHEREFORE, IT IS ORDERED that the stay of the Licensing Board's April 18, 1979 Initial Decision is lifted and that l the Director, Office of Nuclear Reactor Regulation, is j authorized, upon making requisite findings with respect to matters not embraced in the Initial Decision of April 18, 1979 or this Supplemental Initial Decision, in accordance with the Commission's regulations, to issue to Applicant,-

l operating licenses for a term of not more than forty (40) 1 years, authorizing operation of the McGuire Nuclear Station, Units 1 and 2, at steady state power levels not to exceed 3,411 megawatts thermal; such licenses may be in such form and content as is appropriate in light of such findings. l l

, v In view of the Commissions Rules of Practice limiting the Board's jurisdiction in a contested operating license proceeding, the Board has made findings of fact and conclu-sions of law on matters actually put into controversy by the parties to the proceeding. In addition, the licenses will not be issued until the NRC Staff has made the findings reflecting its review of the application under the Atomic Energy Act, which will be set forth in the proposed licenses, and has concluded that the issuance of the licenses will not be inimical to the common defense and security and to the health and safety of the public. In addition, the licenses will not be issued until directed by the Commission after the appropriate Appendix B to 10 CFR Part 2 stay review process, if such is applicable. Exceptions to the Decision and requests for stay may be filed within 10 days after the service of this Supplemental Initial Decision. A brief in support of the exceptions should be filed within 30 days thereaf ter (40 days in the case of the staff) . Within 30 days after the service of the brie- 0' appellant (40 days in the case of the Staff) any ot*e. pr. may file a brief l

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.i in support of, or in opposition to, the exceptions.

THE ATOMIC SAFETY AND LICENSING BOARD Emmeth A. Luebke, Member Richard F. Cole, Member Robe rt M . Lazo, Chairman Issued at Washington, D.C.,

this day of May, 1981.

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APPENDIX A Decisional Record The decisional record in this proceeding Duke Power Company (William B. McGuire Nuclear Station, Units 1 and 2, Docket Nos. 50-369 and 50-370) consists of the following:

1. The material pleadings filed herein, including the Commission notices, the petitions and other plead-ings filed by the parties and the orders issued by the Board during the course of this proceeding;

2. The transcript in this proceeding. The transcript of testimony at the evidentiary hearings is in fifteen volumes with pagination from 2674 to 5257;

3. The decisional record regarding the Initial De-cision issued on April 18, 1979.

4. The exhibits received into evidence at the evi-dentiary hearing. These exhibits are identified as follows:

STAFF EXHIBITS Number Identified Received Description G,H,I 4006 4006 " Safety Evaluation Report",

Duke Power Company, McGuire Nuclear Station, Units 1 &

2, Supplement No. 2, 3, & 4.

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. v Number Identified Received Description J 4006 4006 " Final Environmental State-ment", Duke Power Company, William B. McGuire Nuclear Station, Unit 1 & 2, NUREG-0063, addendum, January, 1981.

K 4007 4353 "NRC Staff Analysis of Hydrogen Control Measures",

Duke Power Company, William B. McGuire Nuclear Station, Unit 1 & 2, Docket Nos. 50-369 and 50-370, February, 1981.

• M 4656 4663 R& D Associates Report.

O 5125 5126 Figure 22.2-2B, Supplement

1. 4 to the " Safety Evaluation Report" for Sequoyah, NUREG-0011.

P 5174 5175 Figure 22.2-2A, Supplement

1. 4 to the " Safety Evaluation Repo rt" for Sequoyah, NUREG-0011.

APPLICANT'S EXHIBITS SA,B,C,D 3118 3118 "An Analysis of Hydrogen Con-trol Measures at McGuire Nuclear Station", Volumes 1, 2, 3, & 4.

SE 3298 3298 Applicant's errata sheet to Volume 2 of a 4 Volume doc-ument.

6 3336 3337 Three page document entitled

" Air Return Flow Paths to Lower Containment".

7 3490 3618 One page document entitled

" Lattice Frame".

Not admitted for the truth of the matter contained therein, and cannot be the basis for proposed findings, Tr. 4663.

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, v Number Identified Received Description 8 4674 4674 Stipulations Regarding CESG's Psychologists, March 17, 1981.

INTERVENOR'S EXHIBITS .

40 3225 4564 Sandia Draft letter from Marshall Berman, Sandia National Laboratories, to Thomas E. Murley and Denwood F. Ross, United States Nuclear Regulatory Commission, February 9, 1981, and attached report.

40A 4670 4670 Sandia Final letter from Marshall Berman, Sandia National Laboratories to Thomas E. Murley and Denwood F. Ross, United States Nuclear Regulatory Commission, Februry 9, 1981, and attached report.

• 59 3822 4654 Memorandum to R.A. Beri from W .T . Pratt, Brookhaven National Laboratories, "Some Very Pre-liminary Results of a Short-Term Analysis (3 week study) of Hydrogen Combustion during Degraded Core Accidents in the Sequoyah Nuclear Plant in the Presence of Glow ilugs",

January 15, 1981.

s 60 3823 4654 One page from the Encyclopedia Britainnica, describing the meaning of solder.

61 4523 4526 Table 9-1, Dominant Accident Sequences - Sequoyah Plant (one page).

• Not admitted for the truth of the matter contained therein, and cannot be the basis for proposed findings, Tr. 4663.

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, s.

UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION BEFORE THE ATOMIC SAFETY AND LICENSING BOARD In the Matter of )

)

DUKE POWER COMPANY ) Docket Nos. 50-369

) 50-370 (William B. McGuire Nuclear )

Station, Units 1 and 2) )

CERTIFICATE OF SERVICE I hereby' certify that copies of " Applicant's Proposed Findings of Fact and Conclusions of Law in the Form of a Supple-mental Initial Decision" dated April 8, 1981 in the captioned matter, have been served upon the following by deposit in the United States mail this 8th day of April, 1981.

Robert M. Lazo, Esq. Edward G. Ketchen, Esq.

Chairman, Atomic Safety and Counsel for NRC Regulatory Licensing Board Staff U.S. Nuclear Regulatory Office of the Executive Commission Legal Director Washington, D.C. 20555 U.S. Nuclear Regulatory Commission ,

Dr. Emmeth A. Luebke Washington, D.C. 20555 '

Atomic Safety and Licensing Board William L. Porter, Esq.

U.S. Nuclear Regulatory Associate General Counsel Commission Duke Power Company Washington, D.C. 20555 Post Office Box 33189 Charlotte, North Carolina 28242 Dr. Richard F. Cole Administrative Judge Chairman U.S. Nuclear Regulatory Atomic Safety and Licensing commission Board Panel Atomic Safety and Licensing U.S. Nuclear Regulatory Board Panel Commission Washington, D.C. 20555 Washington, D.C. 20555 Jesse L. Riley Diane B. Cohn President William B. Schultz Carolina Environmental Study Group Public Citizen Litigation Group 854 Henley Place Suite 700 Charlotte, North Carolina 28207 2000 P Street, N.W.

Washington, D.C. 20036 i

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t Chairman, Atomic Safety Shelly Blum, Esq.

and Licensing Appeal Board 1402 Vickers Avenue U.S. Nuclear Regulatory Durham, North Carolina 27707 Commission Washington, D.C. 20555 Chase R. Stephens Docketing and Service Section Dr. John M. Barry Office of the Secretary Department of Environmental U.S. Nuclear Regulatory Health Commission Mecklenburg County Washington, D.C. 20555 1200 Blythe Boulevard Charlotte, North Carolina 28203

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.A /-lwl ef m r/t- j f e-aww' u/

J. Michael McGarry, III i

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