ML20045H711

Application for Amend to License NPF-29,changing TS to Eliminate Previous Retrictions on Ensuring Operability of Igniters in Encl Areas & Igniters in Open Areas Adjacent to Inoperable Igniters & Redefining Hydrogen Ignition Sys

ML20045H711
Person / Time
Site:	Grand Gulf
Issue date:	07/14/1993
From:	Hutchinson C ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
Shared Package
ML20045H712	List: ML20045H711 ML20045H713
References
GNRO-93-00002, GNRO-93-2, NUDOCS 9307210168
Download: ML20045H711 (13)

Text

AA

.' ^ _ %

~;~ENTERGY fTE" F" "* '" '

~.~-m

'([Si D725;i C. R. Hutchinson July 14, 1992 m cuo. ,

U.S. Nuclear Regulatory Commission Mail Station PI-37 Washington, D.C. 20555 Attention: Document Control Desk

Subject:

Grand Gulf Nuclear Station Docket No. 50-416 License No. NPF-29 Hydrogen Ignition System Technical Specification Changes Proposed Amendment to the Operating License (PCOL-93/01)

"RO-93/00002 Gentlemen:

Entergy Operations, Inc. is submitting by this letter a proposed amendment to the Grand Gulf Nuclear Station (GGNS) Operating License. The proposed amendment is based on the Commission's previously approved letters dated August 10, 1990 and May 6, 1992, regarding generic technical specifications for hydrogen ignition systems and removal of certain component lists from technical specifications, respectively. These changes to the Technical Specifications are requested prior to the start of the sixth refueling outage currently scheduled for October 1993. These changes will, upon approval, assist in the scheduling of maintenance activities during the outage.

This amendment will eliminate previous restrictions on ensuring operability of igniters in enclosed areas and igniters located in open areas adjacent to inoperable igniters. This amendment will also redefine the Hydrogen Ignition System (HIS) as operable based solely on subsystem status. The enclosed revisions are predicated on the enhanced understanding of hydrogen behavior in a Mark III containment which has been developed as a result of the Hydrogen Control Program.

Also, Entergy Operations, Inc. proposes to remove certain lists of components from the GGNS Technical Specifications (TS) in accordance with '

NRC guidance provided in Generic Letter (GL) 91-08. This involves deletion of various TS tables, as well as changes to the TS and Bases as recommended by the GL. The lists being removed from the TS are currently included in plant procedures.

190111 G9306091 - 1 9307210168 930714 PDR ADOCK 05000416

~

) (00k 11 P PDR g

j

. , l July 14 '1993 GNRO-93/00002 ~'

i Page 2 of 5

)

Attachment 2 provides the technical justification and discussion to support ,

the requested amendment. Also included in Attachment 2 is confirmation that the approach and assumptions used to develop the Hydrogen Control Owners Group (HCOG) Generic Technical Specifications are applicable and valid for GGNS. Attachment 3 is a copy of the marked-up TS and TS bases pages. Attachment 4 provides a sample of the proposed TS, and Attachment 5 is a list of reference documents associated with this proposed amendment.

In accordance with the provisions of 10CFR50.4, the signed original of the requested amendment is enclosed. This amendment has been reviewed and accepted by the Plant Safety Review Committee and the Safety Review '

Committee.

Based on the guidelines presented in 10CFR50.92, Entergy Operations has concluded that this proposed amendment involves no significant hazards I considerations. Attachment 2 details the basis for this determination.

Yours truly,

//f A${

CRH/JS/ams attachments: 1. Affirmation per 10CFR50.30 -1

2. GGNS PCOL-93/01

3. Mark-up of Affected Technical Specification Pages

4. Sample Proposed Technical Specification Pages l

5. Reference Documents l cc: (See Next Page) 'l 1

l G9306091 - 2

j July 14, 1993 GNR0-93/00002 -

Page 3 of 5 i cc: Mr. R. H. Bernhard (w/a) '

Mr. H. W. Keiser (w/a)

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

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

Mr. H. L. Thomas (w/o)

Mr. Stewart D. Ebneter (w/a)

Regional Administrator U.S. Nuclear Regulatory Commission ,

Region II 101 Marietta St., N.W., Suite 2900 Atlanta, Georgia 30323 Mr. P. W. O'Connor, Project Manager (w/2)

Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Mail Stop 13H3 Washington, D.C. 20555 Dr. Eddie F Thompson (w/a)

State Health Officer State Board of Health P.O. Box 1700 Jackson, Mississippi 39205 i

G9306091 - 3

,. . Attachment I to GNRO-93/00002 i

BEFORE THE i UNITED STATES NUCLEAR REGULATORY COMMISSION i l

i LICENSE NO. NPF-29 '

t DOCKET N0. 50-416 IN THE MATTER OF MISSISSIPPI POWER & LIGHT COMPANY and SYSTEM ENERGY RESOURCES, INC.

and SOUTH HISSISSIPPI ELECTRIC POWER ASSOCIATION and 1 ENTERGY OPERATIONS, INC.

AFFIRMATION I, C. R. Hutchinson, being duly sworn, state that I am Vice President, Operations GGNS of Entergy Operations, Inc.; that on behalf of Entergy Operations, Inc., System Energy Resources, Inc., and South Mississippi Electric Power Association I am authorized by  ;

Entergy Operations, Inc. to sign and file with the Nuclear Regulatory Commission, this application for amendment of the Operating License of the Grand Gulf Nuclear Station; that I signed this application as Vice President, Operations GGNS'of Entergy Operations, Inc.;

and that the statements made and the matters set forth therein are Jrue and correct-to the best of my knowledge, information and belief. / / //

f, 4 C. R.Hutchinson STATE OF MISSISSIPPI COUNTY OF CLAIBORNE a Notary Public, in and for the County and State above SUBSCRIBED named, this '7 ANDdaySgRNofT0 befpre mp/ ,f ,1993.

udL (SEAL) i LJ .

Notary PubTic Y'U Y?$ ' t$5SSO.$huc avahamwean '

G9306091 - 6

' .' ' Attachment 2 to GNR0-93/00002

,- Page 1 of 9 A.

SUBJECT:

1. PCOL-93/01: Revised GGNS Hydrogen Ignition System Technical Specifications

2. Affected Technical Specifications:

a. Containment and Drywell Hydrogen Ignition System -

Limiting Condition for Operation, Page 3/4 6-S9.

b. Containment and Drywell Hydrogen Ignition System -

Surveillance Requirements, Pages 3/4 6-59 and 3/4 6-60.

c. Hydrogen Igniter Circuits, Table 3.6.7.2-1, Paga 3/4 6-61.

d. Hydrogen Igniters and Location, Table 3.6.7.2-2, Pages l 3/4 6-62, 3/4 6-63, 3/4 6-64, and 3/4 6-65.

e. Bases 3/4 6.7 Atmosphere Control, Page B3/4 6-9 B. DISCUSSION:

1. The Grand Gulf Nuclear Station (CGNS) initiated its hydrogen control program in early 1980 (after the accident at Three Mile Island on March 28,1979) in response to NRC. licensing requirements at the time. GGNS and the Hydrogen Control Owners Group (HCOG) have completed a significant amount of testing and analysis to demonstrate compliance with the Hydrogen Control Rule,10CFR50.44, since inception of the program.

2. On August 10, 1990, the staff issued its Generic Safety Evaluation Report (SER) relating to the Mark III Containment Hydrogen Control Program. The evaluation focused on t_he assessment of the completed generic testing and analyses performed by the Hydrogen Control Owners Group (HC0G) in support of the plant unique analysis. Appendix A of'the staff's Generic SER provided discussion on the proposed generic Hydrogen Ignition Sy. :. n Technical Specification (TS) and its deviations from the cui; it TS.

3. The current GGNS Technical Specifications were developed prior to the completion of the 1/4 scale testing program, and were, by necessity, conservative. Due to the significant volume of test data from the 1/4 scale facility, research information from various combustion industry experts, and analytical studies arising from other HC0G tasks, the level of knowledge of the hydrogen burn phenomena has increased substantially.

It is this enhanced understanding of the hydrogen combustion phenomenon that has provided the basis for developing and 1

G9306091 - 7

I

• Attachment 2'to GNR0-93/00002

. Page 2 of 9 justifying the modified technical specifications, which will provide the same level of protect _ ion to the health and safety of plant personnel and the public, while reducing burdensome testing requirements which result in increased challenges to the system's ability to perform its intended function, and increased exposure to plant testing personnel. The proposed specification revisions are considered an acceptable enhancement to existing operating and surveillance requirements for the Hydrogen Ignition System (HIS).

4. GGNS is requesting revisions to the Technical Specifications (TS) and TS tables listed in A.2 above. These revisions are in accordance with the staff's Generic SER for the Hydrogen Ignition System and previous guidance provided in Generic Letter (GL) 91-08 for removal of component lists from Technical Specifications. The information removed from the TS tables is currently replicated in plant procedures. The +

specific revisions being requested for the aforementioned TS and TS tables are described below.

a. Limiting Condition for Operation (LCO) 3.6.7.2.a is revised to delete previous restrictions on operability of igniters in enclosed areas. Operability requirements '

for igniters in these areas are no longer required due to more current test data and concern for plant personnel safety and exposure limits.  :

b. Limiting Condition for Operation (LC0) 3.6.7.2.b is revised to delete previous restrictions on operability of igniter assemblies adjacent to inoperable igniters in open areas. Operability requirements for igniters in these areas are no longer required due to more current test data and concern for plant personnel safety and exposure limits.

c. TS Tables 3.6.7.2-1 and 3.6.7.2-2 are deleted in their entirety. The information from these tables is currently included in plant procedures which is subject to appropriate change controls.

d. Limiting Condition for Operation (LCO) 3.6.7.2.c is modified to technically redefine the HIS as being operable based solely on subsystem status, in lieu of using circuit and subsystem criteria to define operability status. This change will require that the containment and drywell hydrogen ignition system consist of a minimum of 90% of operable igniter assemblies in each subsystem.

e. Action Statements 3.6.7.2.a and 3.6.7.2.b are being l removed due to deletion of previous restrictions on -

operability of igniters in enclosed areas and igniters G9306091 - 8 i

l- Attachment'2 to GNR0-93/00002

~

-Page 3 of 9 h

adjacent to inoperable igniters in open areas. .The TS tables associated with these actions are also deleted.

These tables are currently reflected in plant procedures.

f. Action Statement 3.6.7.2.c is modified to reflect restoration of the inoperable subsystem within.30 days, or be in at least Hot Shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.

The 30 day completion time is based on the low probability of the occurrence of a degraded core event, the amount of time available after the event for operator action to prevent hydrogen accumulation from exceeding the flammability limit, and the low probability of failure of the OPERABLE hydrogen ignitor subsystem.

g. Surveillance Requirement 4.6.7.2.a is being modified to require that the HIS be demonstrated operable (via current / voltage checks) at least once per 184 days to verify, by energizing the supply breakers, that each subsystem is conducting sufficient current to energize each igniter circuit. ,

h. TS Table 4.6.7.2-1 is deleted in its entirety since operability of the HIS will be based on subsystem status in lieu of circuit / subsystem criteria.

i. Surveillance Requirement 4.6.7.2.b is revised to remove the previous provision that requires energization of supply breakers to verify a visible glow from the' glow plug tip of each normally inaccessible igniter assembly during Cold Shutdown. This requirement will be performed at least once per 18 months for inaccessible ,

igniter assemblies, which will require current / voltage checks be performed. Verification that a visual glow appears from the glow plug tip of each inaccessible igniter assembly is no longer required. Elimination of this action will prevent excessive and unnecessary personnel exposure due to containment entry.

j. Surveillance Requirement 4.6.7.2.c is revised to delete cleanliness inspection requirements for each glow plug.

This change will require energization of each glow plug at least once per 18 months to verify a surface temperature of at least 1700*F for each accessible igniter assembly, and to verify sufficient temperature of 1700*F, by current / voltage checks for igniter assemblies in inaccessible areas. The removal of cleanliness inspection requirements is consistent with the staff's Generic Safety Evaluation Report (SER).

G9306091 - 9

- Attachment 2 to GNR0-93/00002-

. Page 4 of 9 C. JUSTIFICATION:

1. The proposed TS table changes follow the explicit guidance and recommendations of USNRC Generic Letter 91-08. Deletion of TS .

tables will have no substantive affect on surveillance and operability requirements for the HIS. These tables are currently included in plant procedures which require appropriate change controls.

2. The removal of the TS tables will eliminate administrative burdens from GGNS. Additionally, the NRC no longer requires ,

that a license amendment be sought solely to change component information in the affected TS tables. This information will be adequately controlled via the administrative requirements -

specified in TS 6.8 and TS 6.5.3. Those requirements = include review of changes for unreviewed safety questions in accordance with the provisions of 10CFR50.59. Such changes are reported to the NRC in the annual report submitted pursuant to 10CFR50.59. GGNS adheres to a policy of verbatim compliance with all plant procedures.

3. The present GGNS Technical Specifications require that at least two igniter assemblies be operable in enclosed areas.

Enclosed areas (i.e., those areas normally inaccessible due to high radiation or other physical safety concerns), were originally identified as areas of concern since it was then unknown as to where. hydrogen would be released and to what degree it would mix with the containment atmosphere.

Subsequent evaluations have identified the principal hydrogen release points in a Mark III Containment. These hydrogen '

release points do not correspond to areas previously identified as enclosed areas. -These evaluations have further indicated that the hydrogen that is released will tend to mix with the surrounding atmosphere. This mixing will preclude the formation of highly localized, high concentration hydrogen pocketc that could result in_ locally severe deflagrations.

Therefore, the initial concerns that prompted the inclusion of specific operability requirements for igniters in enclosed areas are no longer applicable.

4. GGNS proposes less restrictive operability and surveillance requirements for igniter assemblies in enclosed areas in order to curtail frequent entry of plant personnel into highly radioactive or otherwise physically hazardous environments to perform the required surveillance and maintenance on igniters l

G9306091 - 10 ,

~

Attachment 2 to GNR0-93/00002 Page 5 of 9 in these enclosed areas. Also, based on Item 3 above, separate operability requirements for igniters in enclosed areas are not warranted due to-the-low probability of hydrogen accumulation in enclosed areas.

5. Existing Technical Specifications require that all igniter assemblies adjacent to inoperable igniters be operable. The original purpose was to ensure operable igniters were adequately spaced to ignite local concentrations of hydrogen, and to minimize the distance that flames could propagate from an ignition source before coming into contact with burns -

initiated at an adjacent ignition source. The initial separation criterion used in the design of the hydrogen ignition system was, and is, considered a conservative value. -

The HCOG test data for Grand Gulf indicate that the use of a limited number of igniters, spaced throughout the containment, adequately assures hydrogen ignition and maintenance of hydrogen concentration at low levels. It is proposed that TS requirements relating to igniter assemblies adjacent to inoperable igniters be relaxed in this regard.

6. In the past, requirements concerning igniter assemblies adjacent to an inoperable igniter have resulted in a containment entry whenever at least one igniter is inoperable in each subsystem. Entry has been necessary to determine if the inoperable igniters are adjacent. Due to spacing requirements for the initial installation of the distributed ignition system, many igniter.s are difficult to access to determine their operational status. Although this determination can be made visually at times, it may require construction of scaffolding and access to portions of the containment that result in increased personnel exposure, as well as safety concerns.

7. Existing technical specifications for the Hydrogen Ignition System reflect both subsystem and circuit criteria in defining system operability. Due to the fact that circuits have generally not been installed in a prescribed spatial arrangement, the operability criterion proposed does not include a requirement for the integrity of individual circuits. The proposed system operability criterion ensures that an adequate number of ignition sources are available to mitigate the consequences of hydrogen generation event, without unduly restricting operation or requiring unnecessary

, containment entries.

8. As proposed, with one containment and drywell hydrogen ignition subsystem inoperable, the inoperable subsystem must be restored to OPERABLE within 30 days. The remaining l OPERABLE subsystem is adequate to perform the hydrogen burn function. The 30 day completion time is based on the low probability of the occurrence of a degraded core event that would generate hydrogen in ainounts equivalent to a metal water i G9306091 - 11

'.' Attachment 2 to GNR0-93/00002 Page 6 of 9 reaction of 75% of the active fuel rod cladding, the amount of time available after the event for operator action to prevent hydrogen accumulation from exceeding the flammability limit, and the low probability of failure of the OPERABLE hydrogen ,

igniter subsystem.

9. The proposed technical specifications require that the containment and drywell hydrogen ignition system be demonstrated operable at least once per 184 days. The 184 days frequency has been shown to be acceptable through operating experience because of the low failure occurrence, and provides assurance that hydrogen burn capability exists between the more rigorous 18 month Surveillances. Operating experience has shown these components pass the surveillance when performed at the 184 day frequency. In the event three or more ignitors in either division of the HIS are inoperable, these surveillances will be performed every 92 days until the condition no longer exists. Therefore, this frequency has been concluded to be acceptable from a reliability perspective.

D. APPLICABILITY OF GENERIC HYDROGEN IGNITION SYSTEM (HIS) TECHNICAL SPECIFICATION TO PLANT-SPECIFIC CONFIGURATION:

The staff's Safety Evaluation Report for the Generic Hydrogen Ignition System Technical Specifications requests that each Mark III owner who intends to adopt the generic HIS technical specifications confirm that the HCOG assumptions used in the development of the TS are valid for their plant-specific configuration. The following confirmation is provided:

1. An update to the GGNS Hydrogen Igniter TS is proposed, as documented herein. The new TS will be streamlined by relocation of the detailed tables in the current TS to other areas of administrative control, which will result in a much simplified document without compromising the igniter system reliability.

2. The proposed technical specification is consistent with the stipulations in the Generic Mark III Containment Hydrogen Control SER. The surveillance frequencies and the allowable time to restore a subsystem of the HIS to operable status are consistent with the SER recommendations. To meet the operability criterion, at least 90% of the hydrogen igniter assemblies in the subsystem (i.e., an ESF Division) are required to be operable. This very conservative requirement is also consistent with the recommendation in the SER.

3. The proposed GGNS HIS Technical Specifications are an adaptation of the HC0G Generic HIS Technical Specifications, G9306091 - 12

.- Attachment 2 to GNR0-93/00002 Page 7 of 9 which were developed based on 1/4-scale testing and other research conducted'during the Hydrogen ~ Control Program. The GGNS plant-specific hydrogen combustion testing' in the 1/4 Scale Test Facility was an integral part of the HC0G Generic Hydrogen Control Program and was_ performed in'a consistent manner with other plant-specific and HCOG ' generic testing.

The~ GGNS hydrogen igniter configuration was accurately and.

conservatively modelled in 1/4-scale testing.

Based on the above, the approach and the assumptions used to develop the HC0G Gener!c TS are also applicable to and valid for the. Grand Gulf Nuclear Station configuration.

E. NO SIGNIFICANT HAZARDS CONSIDERATIONS:

9 The Commission has provided standards for determining whether a no significant hazards consideration exists as stated in 10CFR50.92(c).

A proposed amendment to an operating license involves no significant hazards if operation of the facility in accordance' with the proposed amendment would not: (1) involve a significant increase in the probability or consequences of an accident previously evaluated; (2) create the possibility of a new or different kind of accident from '

any accident previously evaluated; or (3) involve a significant reduction in a margin of safety.

GGNS has evaluated the no significant hazards considerations in its request for a license amendment. In accordance with 10CFR50.91(a),

GGNS is providing the following analysis of the proposed amendment against the three standards in 10CFR50.92: i

1. No significant increase in the probability or consequences of an accident previously evaluated results from this change. t The proposed changes would result in the deletion of specified tables from the Technical Specification (TS), as well as modification of TS and Bases as recommended by Generic Letter (GL) 91-08, and in accordance with Appendix A of the Generic Mark III Containment Hydrogen Control Safety Evaluation Report (SER). The tables to be deleted list plant components by ,

division, location, and circuit. The component lists affected are: Hydrogen Igniter Circuits (Table 3.6.7.2-1); Hydrogen Igniters and Locations (Table 3.6.7.2-2); and Number of Igniters by Circuits (Table 4.6.7.2-1). Plant procedures will reflect relocation of the information included in each table specified above. Any changes to this information will be accomplished in accordance with the administrative controls

• required by TS 6.8 and 6.5.3. These controls ensure that there will be no increase in the probability or consequences of previously evaluated accidents without prior NRC approval.

G9306091 - 13

l

~

Attachment 2 to GNR0-93/00002 i

, Page 8 of 9  ;

Operability and surveillance requirements are revised to reflect generically acceptable requirements as described in the Generic SER. Accident analyses which assume hydrogen generation following a LOCA are not affected. There will be  ;

no modifications to plant equipment as a result of the proposed changes.

The hydrogen igniters are passive devices which would be 1 actuated after initiation of a postulated accident. There is no known influence of the Hydrogen Ignition System (HIS) upon the probability of occurrence of the postulated accidents evaluated in the Hydrogen Control Program. Test results described in (3) below also demonstrate that no significant increase in the consequences of previously evaluated accident scenarios would be expected as a result of this change.

Therefore, no significant increase in the probability or consequences of an accident previously evaluated will result from these changes.

2. This change would not create the possibility of a new or different kind of accident from any accident previously evaluated.

The relocation of information from TS tables into plant procedures serves only to consolidate information on affected components outside of the TS for control under appropriate administrative requirements. This is accomplished via the guidance of GL 91-08. The proposed revisions to the TS do not involve a change in the manner in which these components will be operated, maintained, or monitored. No components or systems are physically added, removed, or modified as a result of the proposed changes.

1 The surveillance frequency in the proposed TS is consistent with the present TS and with the Generic Hydrogen Control SER.

Use of current / voltage measurements to determine the operability of igniters in inaccessible areas of containment is consistent with the SER and the present current technical '

specifications, and it minimizes personnel exposure to radiation and other occupational safety hazards.

This TS change does not affect the GGNS emergency operating procedures for the HIS, which are symptomatically based and ,

are intended to encompass the conditions for a wide spectrum ,

of accident conditions. The TS change creates no known possibility of a new or different kind of accident from those previously evaluated.

3. This change would not involve a significant reduction in a margin of safety.

The proposed revisions are being requested as a line item improvement to the Grand Gulf Nuclear Station (GGNS) TS to reduce the administrative burden on the NRC and GGNS when

, G9306091 - 14

-. - - . = - . - _

4 I

Attachment 2 to GNR0-93/00002 Page 9 of 9 revisions to the subject component information become necessary. They are consistent with the guidance of GL 91-08 and the Generic SER for the Hydrogen Ignition System. The margin of safety associated with these component lists is unaffected by this proposed change since the operability and surveillance requirements are in accordance with the Generic SER. Additionally, the information from these tables is ,

currently included in plant procedures which ensure that changes made are reviewed in accordance with the controls of TS 6.8 and 6.5.3. These provisions allow no decrease in the margin of safety without prior NRC approval.  ;

In GGNS plant-specific 1/4-scale testing, igniters were placed l in the test facility at locations which correlated as closely  :

as possible to igniter locations in the plant. In 1/4-scale tests, the igniters in enclosed areas and the second ring of igniters in the containment dome were not simulated. In addition, two other igniters in the containment dome were inoperable for the majority of the test program. Using this very conservative model, hydrogen concentrations were always maintained near the lower flammability limit, demonstrating that the HIS would control hydrogen as designed.

Furthermore, during an HCOG scoping test, all Division I  ;

igniters and several Division II igniters were secured. In an igniter location configuration which was similar to Grand Gulf's, this resulted in a very limited number of igniters being used to simulate the actual number of igniters in the Grand Gulf containment. In this configuration, the ignition time was approximately the same as with the full complement of igniters. No delay in ignition was observed, nor did the combustion phenomena differ. The results of this test provide substantial confidence that the proposed TS, which would require that at least 90% igniters in the containment be operable, is very conservative and does not reduce the necessary margin of safety.

Since igniters in enclosed areas were not simulated, the 1/4-scale test results demonstrate that relaxation of the technical specifications with regard to the adjacent igniter provisions is acceptable and would not reduce the margin of safety inherent in the containment system and the hydrogen ignition system design and operation. Therefore this change, as proposed, does not involve a significant reduction in the margin of safety.

4. Based upon the above evaluation, GGNS has concluded that operation in accordance with the proposed amendment, which is in accordance with the requirements of Generic Letter 91-08 and the Staff's approved Generic Technical Specifications for the Hydrogen Ignition System, involves no significant hazards considerations.

G9306091 - 15 l