ML043240240

Letter Transmitting Generic Letter 2003-01: Control Room Habitability Design Bases, Licensing Bases and Inleakage Testing Results

ML043240240
Person / Time
Site:	Monticello
Issue date:	11/18/2004
From:	Thomas J. Palmisano Nuclear Management Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
GL-03-001, L-MT-04-049
Download: ML043240240 (20)

Text

Monticello Nuclear Generating Plant Operated by Nuclear Management Company, LLC November 18, 2004 L-MT-04-049 10 CFR Part 50 Appendix A, GDC 19 U.S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Monticello Nuclear Generating Plant Docket 50-263 License No. DPR-22 Generic Letter 2003-01: Control Room Habitability - Design Bases, Licensing Bases and Inleakage Testing Results

References:

1)

U.S. Nuclear Regulatory Commission Letter to NMC, NRC Generic Letter 2003-01: Control Room Habitability, dated June 12, 2003.

2)

NMC Letter to NRC, Generic Letter 2003-01: Control Room Habitability 60-Day Response, (L-MT-03-057) dated August 5, 2003, ADAMS Accession No. ML032310424.

3)

NMC Letter to NRC, Generic Letter 2003-01: Control Room Habitability - Response To Commitments, dated November 25, 2003, ADAMS Accession No. ML033300162.

4)

NMC Letter to NRC, Generic Letter 2003-01: Control Room Habitability - Smoke Assessment, (L-MT-04-010) dated February 23, 2004, ADAMS Accession No. ML040550182.

On June 12, 2003, the U.S. Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 2003-01, Control Room Habitability, requesting information on this subject (Reference 1). On August 5, 2003 (Reference 2), Nuclear Management Company, LLC (NMC) provided a partial response and proposed an alternative course of action for the 60-day response as prescribed for in GL 2003-01. This response was specifically for the Monticello Nuclear Generating Plant (MNGP). On November 25, 2003 (Reference 3), NMC provided a schedule for the completion of the commitments related to compliance with GL 2003-01. On February 23, 2004 (Reference 4), NMC provided a detailed Smoke Assessment, specifically for MNGP, which met several commitments made in References 2 and 3.

2807 West County Road 75

• Monticello, Minnesota 55362-9637 Telephone: 763.295.5151

• Fax: 763.295.1454

USNRC Page 2 to this letter provides the response to GL 2003-01 and satisfies the following commitments made in Reference 3:

Perform the ASTM E741 testing and, provide the requested response to Generic Letter Item 1(a).

Verifying by ASTM E741 testing that the most limiting inleakage has been incorporated into the hazardous chemical assessments (GL 2003-01 item 1(b) part 1).

ASTM E741 baseline testing results are provided in Enclosure 1. Results of the current design and licensing basis review performed in accordance with the generic letter identified issues concerning reliance on manual actions. NMC intends to resolve these issues via licensing actions to adopt an alternative source term methodology, resulting in the new commitment below.

Summary of Commitments provides a summary and status of the commitments made for MNGP associated with GL 2003-01. This letter revises the existing commitment and adds a new commitment.

The existing commitment is:

Development of technical specification changes (and any associated plant modifications) to support requested information GL 2003-01 item 1(c).

Schedule for Completion: T = August 2004, T+120 days (2)

(2) Technical Specification submittal dates are contingent on timely approval and issuance of the CLIIP [Consolidated Line Item Improvement Process] for the Technical Specification Task Force (TSTF) - 448 traveler on control room habitability. Completion dates may change based upon any plant modifications determined to be necessary by the testing.

The revised commitment is as follows:

MNGP commits to submit to the NRC proposed changes to the Technical Specifications (and any associated plant modifications) based upon the final, approved version of Technical Specification Task Force (TSTF) traveler - 448, adjusted, as needed, to account for plant-specific MNGP Control Room Envelope design and licensing basis, within 180 days following NRC approval of TSTF-448.

USNRC Page 3 The new commitment is:

NMC will restore full compliance with GDC 19 (e.g., removing reliance on manual actions and ensuring Control Room Envelope inleakage assumptions are met) following the adoption of an alternative source term methodology.

Thomas J. Palmisano Site Vice President, Monticello Nuclear Generating Plant Nuclear Management Company, LLC Enclosures (2) cc:

Administrator, Region III, USNRC Project Manager, Monticello, USNRC Resident Inspector, Monticello, USNRC

ENCLOSURE 1 MONTICELLO NUCLEAR GENERATING PLANT RESPONSE TO NRC GENERIC LETTER 2003-01 DESIGN BASES, LICENSING BASES AND INLEAKAGE TESTING RESULTS On June 12, 2003, the NRC issued NRC Generic Letter (GL) 2003-01, Control Room Habitability, (Reference 1). The GL requested the following information.

1.

Provide confirmation that your facility's control room meets the applicable habitability regulatory requirements (e.g., GDC 1, 3, 4, 5, and 19) and that the Control Room Habitability Systems (CRHSs) are designed, constructed, configured, operated, and maintained in accordance with the facility's design and licensing bases.

Response

The following is a description of the Monticello Nuclear Generating Plant (MNGP)

Control Room Envelope (CRE) and supporting habitability systems. Additional details are provided in the MNGP Updated Safety Analysis Report (USAR) Section 6.7, Habitability Systems.

The MNGP CRE consists of the Main Control Room (MCR) (located on the second floor of the Administration Building) and the first and second floors of the Emergency Filtration Treatment (EFT) Building (excluding the Division II 250 Volt Battery Room on the first floor). Figure 1 illustrates the CRE and surrounding structures. The MCR Heating and Ventilation (CRV) and Emergency Filtration Train (EFT) System is designed to maintain a habitable environment in the MCR during normal and accident conditions. Figure 2 provides a depiction of the CRV-EFT System and the CRE. The CR ventilation mechanical systems (second floor of the EFT Building) communicate with the MCR via ducting through the southeast corner of the Turbine Building. A three-hour fire barrier separates the two CRV-EFT trains. Each train shares a common outside air intake. The CRV subsystem provides HVAC to the CRE during normal and emergency operation. Blanking plates were installed in each CRV train air intake duct, due to historical unfiltered inleakage concerns; thus each CRV train operates as a recirculation-only subsystem. Fresh air is provided to the CRE by operation of the EFT subsystems. The EFT subsystem is designed to operate under emergency conditions to maintain the CRE at a positive pressure for radiological events and at a neutral pressure for events involving the release of toxic or hazardous chemicals.

The Division II 250 Volt Battery Room fans are located within the CRE (EFT Building -

second floor) and the supply and exhaust ducts traversing through the CRE are a potential source of unfiltered inleakage. The battery room receives unfiltered outside air from the CR air intake and receives conditioned air exhausted from the CRE. See Figures 1 and 2 for the relation of the Division II 250 Volt Battery Room to the CRE.

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ENCLOSURE 1 The CRV-EFT ventilation mechanical systems are contained on the second floor of the EFT Building. Major components of the CRV subsystem are a full capacity air conditioning unit, recirculation/exhaust fan and associated instrumentation and controls.

Major components of the EFT subsystem are a radiation monitor, a low efficiency filter, an electric heating element, a high efficiency particulate air (HEPA) filter, charcoal adsorber beds, another HEPA filter, and a centrifugal fan. The charcoal adsorber removes gaseous iodine, and the HEPA filters remove particulate matter.

On detection of high radiation the EFT automatically pressurizes the MCR with filtered air to minimize the activity, and therefore the radiological dose. This permits occupancy of the MCR under accident conditions without personnel receiving radiation exposures in excess of 5 rem whole body, or its equivalent to any part of the body, for the duration of the accident.

The design and operation of the CRE and the CRV-EFT System at MNGP present few vulnerabilities with respect to unfiltered inleakage. The major components of the CRV-EFT System are contained within the CRE with the exception of the Seismic Class I ducts between the EFT Building and the MCR. Normal pathways (i.e., unfiltered supply ventilation pathways) have been sealed with blank flanges to eliminate potential sources of inleakage. Required Technical Specification (TS) surveillance testing of the CRV-EFT demonstrates the capability of the system to maintain a positive relative pressure. Test results confirm the ability to pressurize the CRE to approximately 0.25 inch watercolumn (WC), providing margin to the TS limit of greater than 0.0 inch WC.

The General Electric Principle Design Criteria are the original design and licensing basis of the plant. The EFT subsystem satisfiesSection III.D.3.4 of NUREG-0737, which imposes General Design Criteria (GDC) 19.

Below is an evaluation of the MCR design with respect to each applicable GDC.

GDC 1 - Quality Standards and Records The reactor facility's essential components and systems were designed, fabricated, erected and perform in accordance with the specified quality standards which are, as a minimum, in accordance with applicable codes and regulations. The systems and associated components important to safety are tested, maintained, and operated in accordance with the MNGP Operational Quality Assurance Plan (OQAP). The MNGP OQAP(1) satisfies the requirements of 10 CFR 50, Appendix B, Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants. The MNGP OQAP is constructed and implemented to ensure that the MNGP structures, Page 2 of 13 1

On October 31, 2003, NMC applied to replace the individual sites quality assurance program descriptions with a common NMC Quality Assurance Topical Report (QATR).

When approved this NMC QATR will replace the MNGP OQAP.

ENCLOSURE 1 systems and components important to safety are tested and operated in conformance with the regulatory requirements and design bases of the plant.

The EFT System was designed and installed as a safety related system.

Calculations and specifications for the system were controlled in accordance with a qualified Quality Assurance program.

GDC 3 - Fire Protection The MNGP CRE meets the requirements of GDC 3. Fire Protection Systems meeting the requirements of GDC 3 are installed. Fire in the MCR and adjacent areas was addressed in the original plant design including the capability to shut down the reactor from outside the MCR (Final Safety Analysis Report (FSAR) originally submitted November 7, 1968 in support of NSPs application for a facility operating license, with revisions through November 3, 1969). 10 CFR 50.48 and 10 CFR 50 Appendix R later imposed significant changes that were reflected in the plant fire protection program.

The MCR is separated from other adjacent areas by three-hour fire rated walls, ceilings and floors. Fire detectors, emergency lighting and portable fire extinguishers are also installed in the MCR. The safe shutdown analysis has demonstrated that there are alternative means to safely shutdown the facility in the event of a fire in the MCR. If extensive fire damage occurs which impacts redundant control features, the alternate shutdown panels are provided outside of the MCR to safely shut down the facility.

A qualitative smoke assessment was provided to the NRC by letter dated February 23, 2004 (Reference 4). This assessment was developed in accordance with the guidance of Regulatory Guide (RG) 1.196 and Nuclear Energy Institute (NEI) document 99-03. It evaluated the impact that the propagation of cold smoke within the MCR, access/egress pathways, and alternate shutdown areas would have on the ability of operations personnel to safely shut down the plant. The assessment addressed actions available to the operators, for various degrees of smoke ingestion/generation within the CRE, using current procedures.

The assessment confirmed that the MCR and remote shutdown panel are separated by multiple ventilation and fire zones. A single credible smoke event will not simultaneously affect CRH while blocking egress to or operation from the remote shutdown panel.

The assessment resulted in the creation of procedural guidance to address operator response to the propagation of cold smoke within the envelope.

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ENCLOSURE 1 GDC 4 - Environmental and Dynamic Effects Design Basis Components of the Engineered Safety Features (ESF) which are required to function after design basis accidents or incidents are designed to withstand the most severe forces and environmental effects, including missiles from plant equipment failures anticipated from the events, without impairment of performance capability and without accentuating adverse after effects of the accident.

NSP submitted a study in response to NUREG-0737, Item III.D.3.4, that evaluated chemicals stored on site and chemical shipments near the site. The Control Room Habitability Toxic Chemical Study was updated in 2002. The revision included a review of off-site and on-site chemicals using SARA III information and on-site approved chemical lists. The 2002 update did not identify any new chemical hazards to the site.

The CRE is a mild environment from an Environmental Qualification perspective.

The CRE is surrounded by the Administration Building, Turbine Building and Reactor Building. All postulated High Energy Line Break (HELB) areas adjacent to the CRE are separated from the CRE by HELB barriers that ensure a HELB will not affect the MCR environment.

GDC 5 - Sharing of Structures, Systems and Components GDC 5 does not apply to MNGP since it is a single unit plant, which is not located within the exposure range of any other nuclear facility.

GDC 19 - Control Room Habitability The MNGP FSAR addressed the issue of Control Room Habitability (CRH) by demonstrating conformance with the General Electric Principle Design Criteria (Criterion 11) for a design basis accident. The issues addressed were:

3/4 automatic isolation function of the MCR ventilation air inlet radiation monitor (FSAR Section 6.2.8),

3/4 operation and bases of the MCR HVAC System (FSAR Section 3.2.2.5), and 3/4 MCR shielding design (FSAR Section 3.1.4).

Additionally, the capability to shut down the reactor from outside the MCR was described in FSAR Section 13.4.6.

In 1981, NSP committed to install an MCR air treatment system that would generally satisfy the latest NRC criteria specified in NUREG-0737, Item III.D.3.4.

The Design Report submitted by NSP for staff review summarized licensing considerations and radiological analysis consequences to establish EFT Page 4 of 13

ENCLOSURE 1 performance parameters in conformance with GDC 19. The report stated that the guidelines given in Section 6.4 of the Standard Review Plan (SRP) and RG 1.3 were used in the system design with an exception of determination of atmospheric dispersion factors (/Q) for the MCR and TSC. See the description of the EFT system provided in Response 1.

In its Safety Evaluation, the NRC documented the review performed by its contractor, Pacific Northwest Laboratories (PNL), who evaluated the information provided by NSP against the guidance and requirements of SRP Sections 2.2.1, 2.2.2, 2.2.3 and 6.4, and RGs 1.78 and 1.95. PNL concluded that the modifications proposed by NSP (installation of the EFT System) would meet the requirements of GDC 4 and GDC 19.

The current analytical basis is intended to demonstrate conformance with GDC 19 requirements and was developed by General Electric in support of Power Rerate.

The analysis evaluated Loss of Coolant Accident (LOCA) and Main Steam Line Break (MSLB) accidents to confirm dose to individual MCR operators would be within the criteria of SRP Section 6.4. The fuel handling and control rod drop accidents were not re-evaluated under Power Rerate since they were assessed as bounded by the MSLB accident dose. The design basis LOCA analysis (the bounding accident) assumes primary containment in accordance with TS limits.

The current licensing basis LOCA analysis contains the following assumptions for unfiltered inleakage for the MCR:

3/4 0 to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> - 250 cfm 3/4 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> to 30 days - 10 cfm ASTM E741 baseline testing performed June 1 - 4, 2004, demonstrated MCR unfiltered inleakage to be within the above limit for the first 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> post-accident but in excess of the limit thereafter. The inleakage rate during the initial stages (Time (T) < 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />) of an accident is intended to allow for the MCR door openings, and performance of manual backup actuation of non-redundant, non-safety related ventilation unit trip devices and duct closure operations that may be necessary to assure the MCR is adequately pressurized for the duration of the accident. Our current review of these assumptions as discussed in the response to Item 2 concludes that the manual actions cannot be considered as complying with the current licensing basis (CLB) for system operation. NMC intends to resolve the issues related to manual actions via licensing actions to adopt an alternative source term (AST) methodology.

Contributions to the MCR dose were derived from the Power Rerate dose analyses and historical analyses performed in response to Item III.D.3.4 of NUREG-0737.

The current LOCA analysis results demonstrate margin between the resultant doses and the GDC 19 regulatory limits for CRH. The thyroid dose of 13.5 rem is less than half the 30.0 rem GDC 19 limit. The current licensing basis whole body dose Page 5 of 13

ENCLOSURE 1 consists of two components: a 0.095 rem dose calculated as part of Power Rerate and an approximately 2.9 rem shine component which includes plume shine from stack release, plume shine from bypass leakage, and direct shine from the Reactor Building. The resulting whole body dose of approximately 3.0 rem is within the 5.0 rem limit of GDC 19. The margin demonstrated in the dose analysis results for the bounding accident, i.e., the DBA LOCA, together with the integrity of the CRE and readily available proceduralized compensatory measures, are considered adequate to provide reasonable assurance of CRH in the event of an accident. NMC concludes that the available margin demonstrated in the dose analysis to the regulatory limits, given ASTM E741 baseline testing results, provides reasonable assurance that the limits of GDC 19 are not exceeded for the postulated DBA.

Furthermore, operability evaluation results applying an AST methodology affirm the conclusion that GDC 19 limits are not exceeded. However, to address the inconsistencies in the current licensing basis, NMC proposes the following commitment:

NMC will restore full compliance with GDC 19 (e.g., removing reliance on manual actions and ensuring Control Room Envelope inleakage assumptions are met) following the adoption of an alternative source term methodology.

1(a) That the most limiting unfiltered inleakage into your CRE (and the filtered inleakage if applicable) is no more than the value assumed in your design basis radiological analyses for control room habitability. Describe how and when you performed the analyses, tests, and measurements for this confirmation.

Response

The accident radiological analyses assume an unfiltered in-leakage for the MCR of:

3/4 0 to 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> - 250 cfm 3/4 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> to 30 days - 10 cfm The current licensing basis analysis assumption of 250 cfm unfiltered inleakage for the first eight hours of the design basis LOCA includes 10 cfm unfiltered inleakage through doorways for personnel ingress/egress (per RG 1.197) thereafter for a total unfiltered inleakage of 240 cfm. The assumption that total inleakage can be limited to personnel ingress/egress after 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> (10 cfm) is dependent upon 0 cfm unfiltered inleakage through the CRE.

The in-leakage rate during the initial stages (T < 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />) of an accident is intended to allow for the MCR door openings and performance of manual backup actuation of non-redundant, non-safety related ventilation unit trip devices and duct closure operations (see the response to Item 2) that may be necessary to assure the MCR is adequately pressurized for the duration of the accident.

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ENCLOSURE 1 The unfiltered inleakage values were verified through tracer gas testing performed during June 1 - 4, 2004. The tests were performed in accordance with ASTM E741 and site procedures, which established limiting conditions for CRE and adjacent area ventilation systems. Test results validated that the inleakage assumptions in the CLB analysis for T < 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> are supported by the EFT system. However, the testing showed that inleakage assumptions in the CLB are not bounded for the period of T 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />. The following table provides a synopsis of the results.

TEST PERFORMED ACCEPTANCE CRITERIA RESULTS A Train EFT - Pressurization Mode T < 8 Hour 240 cfm 100 +/- 25 cfm B Train EFT - Pressurization Mode T < 8 Hour 240 cfm 49 cfm(2)

A Train EFT - Pressurization Mode T 8 Hour(1) 0 cfm 16 cfm(2) 1 Only the A Train EFT was tested in the 8 hour9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> mode, since this train had the most limiting (greatest) inleakage rate.

2 In RG 1.197 the NRC has concluded that it is not necessary to include the uncertainty for a CRE inleakage value less than 100 cfm.

Since ASTM E741 baseline testing indicated that the inleakage assumptions in the CLB analysis for T 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br /> were not met an operability evaluation was prepared using an alternative source term methodology as discussed in the NEI White Paper, Use of Generic Letter 91-18 Process and Alternative Source Terms in the Context of Control Room Habitability. This analysis demonstrated that whole body and thyroid dose limits are not exceeded provided continuous unfiltered inleakage is less than approximately 500 cfm.

1(b) That the most limiting unfiltered inleakage into your CRE is incorporated into your hazardous chemical assessments. This inleakage may differ from the value assumed in your design basis radiological analyses. Also, confirm that the reactor control capability is maintained from either the control room or the alternate shutdown panel in the event of smoke.

Response

Hazardous Chemical Assessments Due to the toxicity of commonly used chemicals, which may be transported near the MNGP by railroad or highway, a survey was performed to predict which chemicals may become hazardous in the event of a spill. The analysis was performed in conformance with the guidance set forth by Regulatory Guide 1.78 and NUREG-0570. The analysis results were submitted to the NRC for review as required by NUREG-0737, Item III.D.3.4.

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ENCLOSURE 1 A revised toxic chemical survey was performed in 1993 that identified toxic chemicals in sufficient quantities stored on-site, stored in the vicinity of the site, or shipped near the plant at sufficient frequency to warrant further evaluation. For chemicals meeting any of these criteria, the evaluation indicated that MCR personnel would have at least two minutes to don breathing apparatus before incapacitation limits were exceeded. The results of the 1993 survey and evaluation were submitted and approved by the NRC.

In 1998, the list of postulated spills was reviewed. The 1993 methodology was used, with updated MCR air intake rates and volumes, to determine event duration. These event durations were then used to size the MCR Breathing Air System.

In 2002, an update to the 1998 study using the most recent information available for on-site and off-site chemical sources was performed. The 2002 update did not identify any new chemical hazards to the site.

The most recent update to the toxic chemical assessment assumes 1800 cfm inleakage for the duration of the accident. ASTM E741 inleakage testing described in the response to Item 1(a) demonstrated that MCR unfiltered inleakage is acceptable in the recirculation (toxic chemical) mode as shown below.

TEST PERFORMED ACCEPTANCE CRITERIA RESULTS B Train CRV - Recirculation Mode(1) 1800 cfm 188 +/- 9.5 cfm 1

Since all recirculating boundary dampers and system ductwork outside the CRE is common to both trains, an A Train CRV recirculating mode test was not deemed necessary.

Smoke Assessment NMC submitted the results of the smoke assessment to the NRC in a letter dated February 23, 2004 (Reference 4). The assessment demonstrated that reactor control capability is maintained from either the MCR or Alternate Shutdown System panel during a smoke event.

1(c) That your technical specifications verify the integrity of the CRE, and the assumed inleakage rates of potentially contaminated air. If you currently have a differential pressure (P) surveillance requirement to demonstrate CRE integrity, provide the basis for your conclusion that it remains adequate to demonstrate CRE integrity in light of the ASTM E741 testing results. If you conclude that your P surveillance requirement is no longer adequate, provide a schedule for: 1) revising the surveillance requirement in your technical specification to reference an acceptable surveillance methodology (e.g., ASTM E741), and 2) making any necessary modifications to your CRE Page 8 of 13

ENCLOSURE 1 so that compliance with your new surveillance requirement can be demonstrated.

If your facility does not currently have a technical specification surveillance requirement for your CRE integrity, explain how and at what frequency you confirm your CRE integrity and why this is adequate to demonstrate CRE integrity.

Response

Differential pressure (P) surveillance testing alone cannot verify or quantify CRE unfiltered inleakage. However, P surveillance testing together with ASTM Standard E741 baseline testing does provide insight into CRE integrity. In June 2004, unfiltered air inleakage tests were performed on the MNGP CRE, in accordance with the ASTM E741 standard. The scope of this testing and the test results have been previously discussed in response to Items 1(a) and 1(b) above.

For a plant demonstrating large positive P (MCR to surrounding spaces) and high inleakage during testing, it is obvious that P and inleakage cannot be correlated.

However, ASTM E741 baseline test data for the MNGP CRE shows a correlation between P and inleakage. During the ASTM E741 testing adjacent area ventilation fan line-ups were changed to obtain a range of inleakage versus P values. The results showed that with a positive CRE pressure low inleakage was achieved. As increasingly negative P was observed, the inleakage increased. The results also indicate that leakage from other ventilation systems ductwork within the CRE (i.e., the Division II 250 Volt Battery Room supply and exhausts), low pressure CRV-EFT ductwork outside the CRE, and CRV air inlet dampers is insignificant (approximately 16 cfm). Therefore, for the low-leakage MNGP CRE (assuming no change in the conditions discussed above) a decrease in P would be caused by increased out leakage through other portions of the boundary (i.e., doors and penetrations). Given the above, a positive P demonstrated via periodic TS surveillance testing of the MNGP CRE indicates that leakage is maintained at a low level. As the results demonstrate, MNGP has a tight CRE.

NMC performs P testing of the CRE relative to adjacent areas at least once every operating cycle in accordance with TS Surveillance Requirement 4.17.B.2.c. NMC also performs visual inspections in accordance with existing procedures at least once every operating cycle. These inspections verify the integrity of the ductwork, dampers, air handling units, air filtration units, walls, ceilings, floors, penetrations, doors, and equipment seals to ensure that the equipment is in good working order and there has been no degradation of the boundary. These inspections make sure that the seals, penetrations, equipment and duct barriers are controlled to ensure plant barriers are maintained in their as designed condition.

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ENCLOSURE 1 Based on the test results performed in accordance with ASTM E741 and ongoing periodic inspections, an MNGP TS requirement for periodic testing other than the current P test is not warranted until the issues involved with the Technical Specification Task Force (TSTF) - 448 traveler on control room habitability are resolved. However, in the interim, if significant repairs or modifications are performed another ASTM E741 test will be performed if warranted.

In Reference 3, NMC made the following commitment:

Development of technical specification changes (and any associated plant modifications) to support requested information GL 2003-01 item 1(c)

Schedule for Completion: T = August 2004, T+120 days(2)

Note 2 to the commitment table indicated that the Technical Specification submittal dates were contingent on timely approval and issuance of the Consolidated Line Item Improvement Process (CLIIP) TSTF-448 traveler on control room habitability. In November 2003 when Reference 3 was submitted the expectation was that approval of TSTF-448 would occur in the near future. The NMC understanding was that the NRC and industry positions with respect to control room habitability would be resolved, resulting in a common understanding and promulgation of standard guidelines for acceptable Technical Specification requirements. Because the TSTF is not yet approved NMC is revising our previous commitment. Also, since a final version of TSTF-448 has not been issued, a commitment to adopt the TSTF in its entirety cannot be made at this time. The revised commitment is as follows:

MNGP commits to submit to the NRC proposed changes to the Technical Specifications (and any associated plant modifications) based upon the final, approved version of Technical Specification Task Force (TSTF) traveler - 448, adjusted, as needed, to account for plant-specific MNGP Control Room Envelope design and licensing basis, within 180 days following NRC approval of TSTF-448.

2.

If you currently use compensatory measures to demonstrate control room habitability, describe the compensatory measures at your facility and the corrective actions needed to retire these compensatory measures.

Response

NMC does not credit Potassium Iodide as a compensatory measure for CRH. However, MNGP does rely upon manual operator action as a backup for actuation of non-redundant, non-safety related ventilation unit trip devices and closure of a non-redundant isolation damper during the first eight hours following a DBA.

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ENCLOSURE 1 As discussed within LER 90-001 (Reference 5), some spaces adjacent to the CRE are served by non-safety related ventilation units that do not have safety related or redundant trip devices that consequently are not credited to trip following an EFT initiation. Operation of these ventilation units has the potential to adversely affect achieving a positive pressure differential between the CRE and adjacent spaces, therefore, operators are required by procedures to manually trip these units within the first eight hours of a DBA if pressurization cannot be achieved.

Additionally, there is one section of ductwork that is required to be isolated when the EFT is initiated into pressurization mode. This section of ductwork does not have a redundant damper and therefore a single failure concern exists since this damper could fail to close. Due to this, NMC has installed a manual blanking plate that is loosely installed. In the event of a DBA, operators have eight hours to secure this blanking plate if pressurization cannot be achieved.

MNGPs current licensing basis dose analysis assumes a significantly higher inleakage rate for the first eight hours of an accident to accommodate operators performance of these manual actions. Use of these manual actions in lieu of the originally designed automatic operation of the EFT are considered to be compensatory measures.

The ASTM E741 baseline inleakage testing described in the response to Item 1(a) demonstrated that MCR unfiltered inleakage is less than 125 cfm in the pressurization mode without manual actions. AST calculations performed for the operability evaluation for the MNGP CRE demonstrate that continued protection of the operator is achieved with an assumed unfiltered inleakage of approximately 500 cfm and that the manual actions are no longer required as compensatory measures. Therefore, NMC will restore full compliance with GDC 19 (e.g., removing reliance on manual actions and ensuring Control Room Envelope inleakage assumptions are met) following the adoption of an alternative source term methodology. Use of the manual actions described above has been entered into our corrective action program to track these issues to final resolution.

3.

If you believe that your facility is not required to meet either the GDC, the draft GDC, or the Principal Design Criteria regarding control room habitability, in addition to responding to 1 and 2 above, provide documentation (e.g., Preliminary Safety Analysis Report, Final Safety Analysis Report sections, or correspondence) of the basis for this conclusion and identify your actual requirements.

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ENCLOSURE 1

Response

As noted in response to Item 1, the drafts GDCs (issued July 1967) were used by the Atomic Energy Commission as guidance in evaluating the original design of MNGP.

That review showed that based on the applicant's understanding of the intent of the draft GDC, it was concluded that the MNGP fully satisfies the intent of the criteria. A detailed discussion of the 10 CFR 50 Appendix A GDCs as applicable to MNGP is provided in response to Item 1 above.

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ENCLOSURE 1 References

1.

U.S. Nuclear Regulatory Commission Letter to NMC, NRC Generic Letter 2003-01: Control Room Habitability, dated June 12, 2003.

2.

NMC Letter to NRC, Generic Letter 2003-01: Control Room Habitability 60-Day Response, (L-MT-03-057) dated August 5, 2003, ADAMS Accession No. ML032310424.

3.

NMC Letter to NRC, Generic Letter 2003-01: Control Room Habitability -

Response To Commitments, dated November 25, 2003, ADAMS Accession No. ML033300162.

4.

NMC Letter to NRC, Generic Letter 2003-01: Control Room Habitability - Smoke Assessment, (L-MT-04-010) dated February 23, 2004, ADAMS Accession No. ML040550182.

5.

LER 90-001, Potential Emergency Filter Train System Inoperability Due to Interaction with Non-Safety Related Equipment.

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ENCLOSURE 2

SUMMARY

AND STATUS OF COMMITMENTS MADE FOR MNGP ASSOCIATED WITH GL 2003-01 The following table provides a summary and status of the commitments made by NMC for the MNGP during correspondence associated with GL 2003-01.

Commitment Where Made How Closed NMC will provide the schedule to perform ASTM E741 testing and the schedule for the requested response to GL 2003-01 item 1(a) for MNGP by December 5, 2003.

Ref. 2 Ref. 3 NMC will provide the schedule for verifying by ASTM E741 testing that the most limiting inleakage has been incorporated into the hazardous chemical assessments (GL 2003-01 item 1(b) part 1) for MNGP by December 5, 2003.

Ref. 2 Ref. 3 NMC will provide the results of a smoke assessment (GL 2003-01 item 1(b) part 2) for MNGP by February 23, 2004.

Ref. 2 Ref. 3 Ref. 4 NMC will provide the schedule for the development of technical specification changes (and any associated plant modifications) to support requested information GL 2003-01 item 1(c) for MNGP by December 5, 2003.

Ref. 4 Ref. 3 Perform the ASTM E741 testing [T] and, [provide] the requested response to GL 2003-01 item 1(a)

Schedule for Completion: T = August 2004, T+ 90 days Ref. 3 This Letter Verifying by ASTM E741 testing that the most limiting inleakage has been incorporated into the hazardous chemical assessments (GL 2003-01 item 1(b) part 1)

Schedule for Completion: T = August 2004, T+90 days Ref. 3 This Letter Page 1 of 2

ENCLOSURE 2 Commitment Where How Made Closed Development of technical specification changes (and any associated plant modifications) to support requested information GL 2003-01 item 1(c)

Schedule for Completion: T = August 2004, T+120 days (2)

(2) Technical Specification submittal dates are contingent on timely approval and issuance of the CLIIP [Consolidated Line Item Improvement Process] for the Technical Specification Task Force (TSTF) - 448 traveler on control room habitability.

Completion dates may change based upon any plant modifications determined to be necessary by the testing.

Revised commitment:

MNGP commits to submit to the NRC proposed changes to the Technical Specifications (and any associated plant modifications) based upon the final, approved version of Technical Specification Task Force (TSTF) traveler - 448, adjusted, as needed, to account for plant-specific MNGP Control Room Envelope design and licensing basis, within 180 days following NRC approval of TSTF-448.

Ref. 3 Modified By This Letter Open New commitment:

NMC will restore full compliance with GDC 19 (e.g., removing reliance on manual actions and ensuring Control Room Envelope inleakage assumptions are met) following the adoption of an alternative source term methodology.

This Letter Open Therefore, the commitments associated with GL 2003-01 have been completed with the exception of the last two items in the table.

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