AECM-88-0156, Final Special Rept on Events Re Interaction of Activities Associated W/Units 2 & 1,including Control of Chlorine Stored in Unit 2 Controlled Area & Leakage of Const Water Sys in Control Bldg

Final Special Rept on Events Re Interaction of Activities Associated W/Units 2 & 1,including Control of Chlorine Stored in Unit 2 Controlled Area & Leakage of Const Water Sys in Control Bldg

ML20151X509
Person / Time
Site:	Grand Gulf
Issue date:	08/09/1988
From:	Kingsley O SYSTEM ENERGY RESOURCES, INC.
To:	Grace J NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
AECM-88-0156, AECM-88-156, R-880809, R0-880809, NUDOCS 8808260004
Download: ML20151X509 (13)

Text

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' l2 l.!! : 02 U & August 9,1988 U. S. Nuclear Regulatory Comission Region 11 101 Marietta St., N.W., Suite 2900 Atlanta, Georgia 30323 Attention: Dr. J. Nelson Grece, Regional Administrator

SUBJECT:

Grand Gulf Nuclear Station Unit 1 Docket No. 50-416 License No. NPF-29 Final Special Report, Unit 1/

Unit 2 Interface AECM-88/0156 On April 9, 1987 System Energy Resources, Inc. (SERI) submitted Special Report. Unit 1/ Unit 2 Interface (AECM-87/0077). This special report provided information concerning events related to the interaction of activities associated with Grand Gulf Nuclear Station (GGNS) Unit 2 (in a suspended construction status) with the operating plant, GGNS Unit 1.

This revision to the earlier Special Report provides a final determination on the reportability of the previous storage of relatively large quantities of fuel gas in the Unit 2 controlled area. The as-found condition was detertnined to be not reportable under 10CFR50.72 and 50.73. A sumary of the issue, the )

as-found condition, and the analysis is provided in Attachment 2 to this Report.

SERI also developed a chronology of key issues and events related to ,

Unit 1/ Unit 2 interface. This chronology discusses key issues related to this subject and discusses the various corrective actions taken, both specific and programatic, to address each issue. The subject document also provides  !

insight as to how the various corrective actions broadened and evolved as I issues were identified. The chronology report is documented in SERI's i project file (PMI-88/04104 datedAugust8,1988). The contents of the report j were discussed with the NRC resident inspectors on August 4, 1988.  !

As discussed with the NRC staff, programatic controls have been l implemented to provide control and the appropriate level of evaluation of l Unit 2 activities as they may impact Unit I safety. These controls are  !

discussed in the attached report. It should be noted that these controls have  !

been developed in a conservative manner to insure proper handling of the j l

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AECM-88/0156 Page 2 Unit 1/ Unit 2 interface. These controls are, however, quite restrictive on Unit 2 activities. Therefore, should construction work recommence on Unit 2, the procedures described in the attached report would require review and revision in order to accomplish the same goal of insuring Unit 1 safety while at the same time not presenting unnecessary constraints on Unit 2 construction activities. Such revicions would be discussed with your staff prior to implementation.

Also, as discussed with the NRC resident inspectors on August 4, SERI committed to hold a future meeting at a mutually agreed upon time to discuss the administrative controls associated with Unit 2 activities. The meeting is appropriate so that the new resident inspector, soon to be assigned to Grand Gulf, can be familiarized with these controls.

If you have any questions regarding this issue, please advise.

Yours t ly, ODK:bms Attachments

• \'-

cc: Mr.T.H.Cloninger(w/a)

Mr. R. B. McGehee (w/a)

Mr. N. S. Reynolds (w/a)

Mr. H. L. Thomas ( /o)

Mr. R. C. Butcher w/a)

Mr.L.L.Xintner,ProjectManager(w/a)

Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Comission Mail Stop 14B20 Washington, D.C. 20555 J16AECM88080201 - 2

Attachment 1 to AECM-88/0156 Revision 1 August, 1988 Grand Gulf Nuclear Station UNIT 1/ UNIT 2 INTERFACE - SPECIAL REPORT

!. BACKGROUND 4

Members of Systems Energy Resources, Inc. (SERI) staff met with the NRC Resident Inspector for Grand Gulf Nuclear Station (GGNS) on -

February 27, 1987. The meeting, held at the plant site, was requested by the NRC Resident Inspector to discuss concerns regarding the impact of  :

activities associated with GGNS Unit 2 (suspended construction status) on the operating plant, GGNS Unit 1. -

During the meeting SERI staff discussed issues identified in 1986 involving the interaction of Unit I and Unit 2. The specific events involved the following subjects.

2 - Control of chlorine stored in the Unit 2 controlled area

- Backflow from a Unit 2 radwaste tunnel sump into the Unit 1 side

- Leakage of construction water system in the Control Building 4

into subfloor sections within the control room envelope  !

- Storage of welding gas in the Unit 2 controlled area  ;

Corrective actions specific to the issues were discussed as well as  !

programatic improvements recently implemented to prevent such events in j the future.

This report sumarizes these issues, key corrective actions, and i

programatic improvements. As comitted in the February 27 meeting, this t

information is being provided in the form of a Special Report. This (

Special Report is being submitted in lieu of a continuation report of

! LER 85-33.

Revision 1 of this report is filed to provide the final reportability determination of the as-found condition associated with the storage of welding gas on the Unit 2 side.

II. CORRECTIVE ACTIONS - SPECIFIC ISSUES A. Storage of Chlorine in Unit 2 Area

1. During inspections condected in April and May 1986, the NRC Senior Resident Inspector raised concerns regarding the storage of liquid chlorine in the Unit 2 area. Procedural controls

governing the control of chlorine were not adequate to ensure FSAR requirements were met. The procedure was revised, however, no detennination was made as to whether or not the procedural revision represented an unreviewed safety question. As a result i a Notice of Violation was issued (50-416/86-17-03, MAEC-86/0208, dated July 3, 1986).

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Attachment I to AECM-88/0156 Revision 1 August, 1988 SERI's response to this violation was provided in AECM-86/0246, dated August 8, 1986. The lack of broad controls of Unit 2 activities and procedures which may affect Unit 1 safety was cited by SERI as the overall cause for the situation identified by the NRC. .

1

2. The specific procedural revision (Bechtel Work Plan / Procedure (WP/P)-14, Revision 8) was screened for 10CFR50.59 applicability and found not to require further evaluation.

3. A review was conducted to identify those activities which may have safety impact on Unit 1 operations. This review effort laid the groundwork for broader controls regarding the evaluation of Unit 2 activities. These latter controls were implemented, as comitted, by November 1,1986.

4. This effort led to the implementation of 10CFR50.59 screening requirements for new or revised precedures governing activities in Unit 2, i.e., the Bechtel Unit 2 "General Work Plan / Procedure" (WP/P) series. To insure the quality of the screening activity, any required screening is performed by personnel qualified under the Unit 1 program.

5. In the process of developing these controls, the need was identified to provide Unit 2 staff sufficient guidance as to which activities require Unit I staff involvement and, in some cases, control room personnel notification. This guidance was ,

provided in the form of a new WP/P and is discussed in Section III of this report.

on January 13,1987.)(Thesubjectprocedure.WP/P-42,was' issued B. Backflow from a Unit 2 Radwaste Tunnel Sump into the Unit 1 Side

1. In July 1986 water was discovered backing up from a Unit 2 radwaste tunnel sump into the Unit 1 side. The occurrence was documented by MNCR 0566-86. As a corrective action the drain lines were plugged to provide pro)er separation between the Units. As a final disposition of t1e MNCR, permanent seals were installed in the drain lines.

2. The potential existed for the release of radioactively contaminated water from Unit 1 to Unit 2 and thus to the environment. However, water samples and surveys of the tunnels showed no evidence that .

this has ever occurred. l

3. A review was conducted to evaluate why the drain line interface was overlooked during the previous drawing review of Unit 1/

Unit 2 interface. It was determined that the drawing which should have indicated the interface was not correct because a temporary separation wall had been added and the interface location was J16AECM88080201 - 5

Attachment I to AECM-88/0156 Revision 1 August, 1988 not properly identified. SERI Nuclear Plant Engineering (NPE) determined that a document review and a walkdown of all temporary Unit 2/ Unit I separation walls was necessary to provide assurance that similar circumstances did not exist.

4. A review was performed of applicable architectural and civil

• design drawings to locate temporary walls / barriers separating Unit 1 from Unit 2. A subsequent walkdown was performed of the temporary walls located by the review. No additional Unit 1/

Unit 2 interface concerns, involving temporary barriers, were identified as a result of the walkdown. The drawing was updated to show the separation wall.

C. Leakage of Construction Water System in the Control Building Into Subfloor Sections Within the Control Room Envelope

1. In September 1986, a water leak was discovered in the subfloor '

within the control room envelope. This water leaked from the Unit 2 side of the Control Room into the Unit 1 side, resulting in some damage to the B0P computer (non-safety related). ,

2. As a result of questions and concerns raised by the Senior '

Resident Inspector, an interim 10CFR 50.59 evaluation was performed and approved by the PSRC allowing continued use of the construction water system in the Control Building based on l continuous watches stationed in the affected areas to monitor for leakage. In addition, a walkdown was conducted of the temporary construction water piping in the Control Building to address Seismic Category II/I, wetting, and flood hazards of the pipe. A potential wetting concern was identified for two ,

electrical isolation panels in the B0P Computer Room (OC403),

and a potential flooding concern was identified for four rooms (OC403, 00404, 0C502, and OC704) containing no floor drains. An engineering evaluation was performed which resolved the concern in the 80P Computer Rooms (0C403 and 0C404), and two isolation valves were installed and tagged shut to isolate construction water from rooms OC502 and OC704. An additional 10CFR50.59 review was perfonned to resolve the concern in OC403 (0C404 contains no Unit I safety related panels), and the continuous watches were discontinued.

3. As a result of this issue, a walkdown of Control Building areas not yet turned over to Unit I was initiated. These areas were evaluated for the presence of conditions which could affect safe Unit 1 operation including Seismic Category II/I hazards, internally generated missiles, flooding and spraying, transient combustibles, inoperable floor drains, fire sprinkler actuation, temporary equipment and water migration to other areas. Material Nonconformance Reports (MNCR) were ganerated for one Seismic Category II/I concern (MNCR 0027-87) and for two penetration closures (MNCR 0037-87). Corrective actions have been taken as l necessary to disposition these MNCR documents.

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l Attachment I to AECM-88/0156 Revision 1 August, 1988 D. Storage of welding gas in the Unit 2 Area

1. As part of the development effort of WP/P-42, a listing of potentially hazardous chemicals was generated. The maximum storage container size was also identified. This listing was included as an appendix to WP/P-42. WP/P-42 was implemented following a 10CFR50.59 evaluation.

2. In developing the listing discussed above, large tanks of fuel gases were identified in the Unit 2 area. As a conservative measure, these tanks were emptied and purged. These bulk storage tQks are not includsd in the WP/P-42 appendix. The future addition of tanks to the appendix, i.e., use of tankt to store hazardous gas, would be required to have an evaluation to 10CFR50.59.

3. A reportability determination on the as-found condition, i.e.,

prior to removal of the fuel gas from the site, has been completed. The determination is summarized in Attachment 2 of this Report and concluded that presence of the fuel gas did not '

represent a condition reportabic under 10CFR50.72 or 50.73.

III. PROGRAMMATIC CONTROLS Progransnatic controls for Unit 1/ Unit 2 Interface are defined in WP/P-42.

A. Purpose WP/P-42 establishes the requirements for Bechtel Construction inter-face with Unit 1 to ensure that Unit 2 construction activities do not aaversely affect the safe operation of Unit 1. This procedure provides controls to ensure prior approval is obtained from the organization responsible for establishing compensatory measures for .

any Unit 2 construction or maintenance activity that has the potential to effect the safe operation of Unit 1.

B. Related Procedural Controls WP/P-42 establishes the control of Unit 1/ Unit 2 interface. Other Bechtel procedures provide control of specific areas that are important to the interface. WP/P-42 results in a cohesive interface program through reference to these other procedures and the areas to which they apply.

1. WP/P-1, "Establishment Control and Implementation of the Construction Work Plan / Procedure Program", defines program responsibilities and requirements, the components of the WP/P Program, the format for program documents, the preparation, approval and revision of program documents and their distribution and control.

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• Attachment 1 to ;

-AECM-88/0156 Revision 1 August, 1988 Change Request 406 to WP/P-1 requires that new General WP/Ps ,

and revisions or change requests to existing General WP/Ps shall be reviewed in accordance with 10CFR50.59 to detennine whether or not an unreviewed safety question is involved prior to impicmentation.

2. WP/P-3, "Housekeeping of Nuclear Power Plants", requires the control of combustible materials.

3. WP/P-14. "Material Centrol", provides controls for construction

! activities associated with the-shipping, handling, storage and identification of materials and equipment to prevent damage, deterioration or loss.

Appendix "A" of WP/P-14 specifically addresses the requirements 1

for controlling the storage and use of Liquid Chlorine.

C. Interface Areas Considered WP/P-42 requires that all proposed construction / maintenance work activities be reviewed to determine their potential for adversely ,

affecting Unit 1 operation. The following eleven (11) areas of interface are specifically addressed.  ;

1. Safety  ;

f

2. Security

3. Radiation Protection

4. Control of Hazardous Materials

5. Fire Prevention and Protection l

6. Flood Protection [

7. Missile Protection

8. Control of Rigging and Heavy Loads

9. Area or System Integrity Protection (work activities involving  :

systems or areas having interdependence between Unit 1/ Unit 2 I approved by Unit 1 Plant Staff prior to start of work) i

10. Control of the Temporary Construction Water System

! 11. Control of Temporary Power l

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o Attachment I to AECM-88/0156 Revision 1 August, 1988 D. Proposed Activity Evalgation and Unit 1 Involvement Implementation of Unit 2 construction / maintenance work activities under WP/P-42 is as follows.

1. Activities are reviewed to determine their potentisl for adversely affecting the safe opt: ration or security of Unit 1.

The principal document facilitating this review is the-Construction Interface Review Checklist (CIRC). ,

The CIRC has been constructed to lead the originatt,.* and subsequent reviewers to two key determinations. (1)Shouldthe activity be screened for 10CFR50.59 applicability? (2)Is ,

notification of control room personnel required? The CIRC criteria have been developed such that a conservative determination will be made. For example, for any proposed Unit 2 work activity in the Control Building or a Unit 2 work activity involving a Unit 1 system, structure, or shared system .

or structure, further screening for 10CFR50.59 applicability '

woutd be required.

Key elements in the generation of a CIRC are as follows:

a. The scope of work and work location are clearly defined,

b. The responsible field engineer screens the proposed work activity for potential impact on Unit 1 by answering the questions on the CIRC.

c. The CIRC is reviewed by the Lead Discipline Engineer and requires the concurrence of the Project Field Engineer.

2. Activities determined to have the potential to adversely affect the safe operation or security of Unit 1 are sunnarized on a Control Room Notification Form (CRNF). The CRNF, in addition to identifying the work scope, system and work location (from CIRC), provides for the identification of special requirements, '

applicable Unit 1 procedures, number of persons required for the work, scheduled start date and estinated duration. The CRNF, with a copy of applicable work documer.ts and instructions, is routed to Unit 1 Plant Staff.

a. A review for 10CFR50.59 applicability 15. performed for the '

. CRNF work package by a qualified reviewer from Unit 1 Plant Staff.

b. The CRNF work package is then routed or hand carried to the Operations Shift Superintendent for his review and  :

approval, r

J16AECl488080201 - 9  ;

t

. Attachment 1 to AECM-88/0156 Revision 1 i August, 1988

3. Work is accomplished in accordance with the CRNF work package following approval by the Shift Superintendent. Work is performed in compliance with the GGNS Quality Program using Work Plan and Inspection Records. Engineering drawings and specifications with WP/P-42 providing assurance that the special requirements of the operating plant are met. By procedure ,

appropriate Unit 1 organizations are notified of work completion in a timely manner.

IV. CONCLUSIONS With regard to the specific issues related u she Unt' 1/ Unit 2 interface-described in this report, SERI believes thin thor ^ug;, end appropriate corrective actions have been taken. The t.w. ,.re and use of relatively large quantities of fuel gas on the Unit 2 sitt has *een evaluated and determined to be not reportable under 10;FR50.72 and 0 .73. The tanks have been emptied and any future use would req # e avaluation to 10CFR50.59.

SERI recognizes that the key element previously lacking in th b area pertained to comprehensive control and safety assessment of Unit 2 activities as they may impact Unit 1 operations. The system of procedural controls now implemented require proper evaluation of any new or revised construction procedures (WP/P series Unit 2 procedures). These controls ,

i also provide Unit 2 staff detailed guidance to be used in the assessment of proposed activities as well as provide the proper level of involvement by qualified Unit 1 operating staff in the decision making process.

Overall. SERI believes these current Unit 1/ Unit 2 interface controls

will be effective in insuring a proper control and assessment of Unit 2 activities as they may impact the safety of Unit 1 operations.

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Attachment 2 to AECM-88/0156 Reportability Assessment Regarding As-found Condition of On-Site Storage of Fuel Gas l

A. PURPOSE This attachment provides a summary discussion of SERI's assessment of reportability of the as-found condition of the on-site storage of relatively large quantities of fuel gas. This assessment is provided as committed in SERI's S.oecial Report on Unit 1/ Unit 2 Interface, AECM-87/0077, dated April 9, 1987.

B. BisCKGR0VND In developing a listing of potentially hazardous chemicals stored on the Unit 2 portion of the GGNS plant site, concerns were raised regarding the hazard to Unit i represented by relatively large t aks of fuel gas stored on the Unit 2 side. This gas had been used pri;.cipally to support Unit 2 construction activities.

As a conservative measure these tanks were emptied and purged. This Attachment summarizes the analysis of t.,e potential hazard and conclusions d. awn from that analysis.

C. STORAGE TANK DESIGN & ARRANGEMENT

1. The subject tanks are located in the Unit 2 area approximately 110 feet directly east of Standby Service ';ater Cooling Tower (SSWCT)

Basin B. The next closest above grcand safety related structure essential to Unit 1 operations is the Control Building. The Control Building is over 500 feet to the southeast of the otorage tank location.

2. There are a total of four storage tanks, asch with a nominal capacity of 1000 gallons. One tank, adjacent but seoarate from the others, stored propane. The other tanks stored MAPF gas and were connected through appropriate valves and piping to a common discharge header. The valving arrangement provided isolation of two MAPP tanks while the remaining tank was in service.

3. The tanks were constructed to appropriate ASME standards, having liquid and vapor primary shutoff valves, excess flow valves, and pressure relief valves. The tanks were installed using the safety feature guidance of Pamphlet 58 of NFPA, "Standard for the Storage and Handling of Liquified Petroleum Gas." The storage tanks and ,

associated valving ar, piping were approved for use by the State of Mississippi Liquified Gas Division. Each tank is protected on three sides by eight inch (8") thick concrete walls. The perimeter is fenced and provided with a locked gate.

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Attachment 2 to AECM-88/0156 D. KEY ASSUMPTIONS & ANALYSIS RESULTS

1. ASSUMPTIONS In assessing the impact of the postulated explosion on the closest safety related structure, the key assumptions used were as follows:

a. The fraction of contents of a ' single container flashing-was determined in accordance with NUREG-570.

b. Only one tank of the 3 tanks released its cor. tents. While_the tanks are connected, the header has isolation valves.and only cne tank is used at a time.

c. Detonation of gas was assumed to be at or near the release location. This assumption is based on consideration of tank and piping design, protective features, use of the tanks, and likely failure modes.

d. Gaussian concentration distribution within the flammable cloud.

2. ANALYSIS and RESULTS

a. STRUCTURAL The analysis focused on the !,5WCT basins due to their proximity to the tanks relative to other Unit 1 Seismic Category I .

structures. The basins are structurally similar; basin B is directly opposite the tank location and would therefore experience the greatest impact from the postulated explosion.

The analysis approach utilized a conservative, equivalent static oressure loading for assessing response. The use of a static equivalent is acceptable per Regulatory Guide 1.91, Revisfor. I and is appropriate based a review of previously generated structural response for the basin, valve room walls, and roof and on the characteristics of explosion loading effects, i.e., the key concern is incident or reflected overpressure loading (

Reference:

Regulatory Guide 1.91). In addition, a conservative factor was applied to increase the static pressure loads used in the analyses.

The results of the analyses indicate that the concrete  !

structural members ai ected by the postulated explosion have design capabilities as determined by ACI-318-71 greater than the i auired strength per the combine loads. Therefore, based on these analyses, it is concluded the SSWCTB would be capable of performing its safety function following this postulated event.

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.. 1

. Attachment 2 to AECM-88/0156 ,

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b. EQUIPMENT Regarding equipment experiencing a direct exposure, the basins were walked down to identify Unit i related equipment that may be I directly exposed 'to the explosion effects. Vertical risers supplying spray headers were the only exposed Unit 1 piping ideatified and was determined to be adequately protected due to its location in the west cells of each basin.

The impact to dynamic equipment qualification of components and equipment stored in the SSWCT basin structure and pumphouse was also assessed. Based on this assessment it was concluded that the ,

equipment's' qualification was not adversely effected. This. i conclusion was based on the consideration of several factors,  !

including the short duration and impulsive nature of the pressure loading. The pressure wave effects on structures and components will i be non-cyclic in nature. Further, the dynamic energy content of the  ;

generated pressure pulse is judged to be significantly lower than that which may be expected during the design basis seismic event from the standpoint of overall structure excitation. For these reasons the postulated explosion was concluded to have no adverse impact on effected equipment'_s dynamic qualification.

E.

SUMMARY

1. Based on this evaluation of impact from a structural and equipment standpoint, it was determined that - postulated explosion would not prevent the effected equipment frt. : rforming their safety functions. Therefore, this conditio.. is not considered reportable under 10CFR50.72 or 50.73.

2. However, due to the relatively large size of the subject tanks, it is highly unlikely that the tanks would be utilized in the future for the storage of explosive gases. The tanks were purged and are ,

currently empty. Any use of these tanks involving a hazardous gas would require an evaluation in accordance with 10CFR50.59 based on the controls implemented to review Unit 2 related activities that may impact Unit 1. l l

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