ML20204G985

Safety Evaluation Re Revised Emergency Action Levels for Limerick Generating Station,Units 1 & 2

ML20204G985
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Site:	Limerick
Issue date:	03/11/1999
From:	NRC (Affiliation Not Assigned)
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ML20204G977	List: ML20204G972 ML20204G985
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NUDOCS 9903260356
Download: ML20204G985 (9)

Text

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j NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20656-0001

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SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION l ON REVISED EMERGENOY ACTION LEVELS FOR PECO ENERGY COMPANY LIMERICK GENERATING STATION. UNITS 1 and 2 DOCKET NOS. 50-352 and 50-353

1.0 INTRODUCTION

By letter dated April 16,1998, as supplemented by letters dated November 16,1998, January 22,1999 and February 11,1999, PECO Energy Company (the licensee) proposed l changes to the Limerick Generating Station (LGS) Units 1 and 2 emergency action levels (EALs). The Office of Nuclear Reactor Regulation's review of these proposed changes against the regulatory requirements contained in 10 CFR Part 50 is described below.

2.0 BACKGROUND

The proposed revision to the LGS Units 1 and 2 EALs was reviewed against the requirements in 10 CFR 50.47(b)(4) and Appendix E to 10 CFR Part 50.

It is specified in 10 CFR 50.47(b)(4) that onsite emergency plans must meet the following standard: "A standard emergency classification and action level scheme, the bases of which include facility system and effluent parameters, is in use by the nuclear facility licensee...".

Appendix E, Subsection IV.B specifies in part that ". . . These emergency action levels shall be discussed and agreed on by the applicant and State and local governmental authorities . . ."

Appendix E, Subsection IV.C specifies that ' emergency action levels (based not only on onsite and offsite radiation monitoring information but also on readings from a number of sensors that indicate a potential emergency, such as the pressure in containment and the response of the Emergency Core Cooling System) for notifiestion of offsite agencies shall be described... The emergencv classes defined sha;. :nclude: (1) notification of unusual events, (2) alert, (3) site area emergency, and (4) general emergency."

In Revision 3 to Regui ~y Guide 1.101," Emergency Planning nd Preparedness for Nuclear Power Reactors," the L. 'O endorsed NUMARC/NESP-007, Revision 2, " Methodology for Development of Ems rgency Action Levels," as an acceptable method for licensees to meet the requirements of 10 C:R 50.47(b)(4) and Appendix E to 10 CFR Part 50. The staff relied upon the guidance in NUMARC/NESP-007 as the basis for its review of the LGS EAL changes.

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2 3.0 - EVALUAT10H The licensee provided Revisions D and D1 of the LGS Technical Basis Manual containing the initiating Conditions (ICs), EALs, and technical basis for the EALs utilized in procedure ERP-101," Classification of Emergencies." l

- Most of the proposed EALs conform closely to the guidar cc wsver, several of the licensee's proposed EALs depart from the example EALs in NUMAl K a-007. Review of the i licensee's justification for these deviations, as discussed be:o . iound the deviations to be l l _ acceptable. The evaluation of the deviations are grouped into the following categories: (1)  !

deviations from NUMARC/NESP-007, e.g., NUMARC/NESP-007 example EALs not included in the licensee's EAL scheme, (2) site-specific indications, e.g., EALs which include unique thresholds or indications, and (3) site-specific additions, i.e., EALs not specified in the NUMARC/NESP-007 guidance which were included in the licensee's EAL scheme.

Deviation #1 AU1-1 NUMARC/NESP-007 EAL AU1-1 reads as fo' lows:

A valid reading on one or r~ ore of the following monitors that exceeds the "value shown" (site-specific monitors) indicates that ,he release may have exceeded the above criterion and indicates the need to assess the release with (Site-specific procedure):

(Site-specificlist)

Note: If the monitor reading (s) ic sustained for longer than 60 niinutes and the required assessments cannot be completed within this period, then the declaration must be made based on the valid reading.

The corresponding LGS EAL (EAL 5.1.1.a) reads as follows:

A valid reading on one or more of the following radiation monitors that exceeds two times the HiHi alarm setpoint value for >60 minutes

! North Stack, South Stack, Radwaste Discharge, Cooling Tower Blowdown AND Calculated maximum offsite dose rato using computer dose model exceeds .114 mrem /hr TPARD [ Total Protective Action Recommendation Dose] OR .342 mrem child thyroid CDE based on a 60 minute average NOTE: if the required dose projections cannot be completed within the 60 minute period then the declaration must be mads based on the valid sustained monitor reading.

The licensee incorporated the condition of dose assessment results into this EAL. This is not specifically identified in the NUMARC/NESP-007 guidance but is implied in the " note" j associated with this EAL. Including the dose assessment re ults in the EAL provides confirmation that the magnitude of the loss of control of radioactive materials exceeds the

threshold for an Unusual Eve ieclaration. Furthermore, the dose assessment results can be p used to determine whether P w t.se exceeds the threshold for classifying at a higher i.

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3 emergency classificatiori .sei. This deviation is acceptable. The LGS EAL corresponding to NUMARC/NESP-007 EAL AA1-1 deviates in a similar manner and is also acceptable.

Deviation #2 Fission Product Barrier -- Main Steam Line Break One of the NUMARC/NESP-007 EALs for the loss of the reac;or coolant system (RCS) barrier reads as follows:

LOSS:

(site-specific) Indication of a Main Steam Line Break LGS removed tr.n ML .bm the fission product barrier table because,if the main steam line isolates a s r!ebei (N: condition does not constitute a loss of the RCS barrier. However, the  !

licensee Isued 'a's wrfisen as an event-based EAL due to the potential dose consequences i associated wW.1. wred. T'is is consistent with the recommendations provided in the industry 4evNr;d & . 1.68 psig and Indication of a leakinside drywell The LGS EAL for the loss of RCS based upon drywell pressure indication deviates from the NUMARC/NESP-007 guidance by including the condition " indication of a leak inside drywell."

The licensee added this statement to its EAL as a " human factor reminder to the Emergency Director that use of this EAL is for accident scenarios only." This was to prevent classifying in the situation where drywell pressure increase is due to a loss of drywell cooling. This deviation is acceptable.

Deviation #4 HU4 NUMARC/NESP-007 IC HU4 reads as follows:

Confirmed Security Event Which Indicates a Potential Degradation in the Level of Safety of tire Plant

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i One of the NUMARC/NESP-007 example EALs under this IC reads as follows:

Bomb device discovered within plant Protected Area and outside the plant Vital Area j LGS did not include this under its Unusual Event Security IC but did include a similar EAL under the Alert level Suurity IC (8.1.2). A bomb discovered within the protected area meets the c7ndition specified in the Alert level Security IC, i.e., " Security Event in the Protected Area."

Therefore this deviation is acceptable.

Deviation #5 SU4 l NUMARC/NESP-007 IC SU4 reads as follows:

FuelCladDegradation The NUMARC/NESP-007 example EALs under this IC are:

1. (Site-specific) radiation monitor readings indicating fuel clad degradation greater than technical specification limits.

2. (Site-specific) coolant samp!e activity value indicating fuel clad degradation greater than technical specification limits, i

l l The applicable modes specified for these EALs in the NUMARC/NESP-007 guidance are "all" modes.

The license provided the following EALs (1.1.1.b and 4.1.1) corresponding EAL 1 above:

l SJAE Radiation (Ofigas Monitor) > 2.1x10' mR/hr i

Main Steam Line HiHi Radiation (3xNFPB [ normal fullpower background])  !

The licensee restricted the mode applicability of these EALs to run, startup, and hot shutdown because these are the only modes in which these monitors will be valid indicators of fuel clad damage. The licensee included an EAL for coolant sampling (" Reactor Coolant activity >4 pCi/gm Dose Equivalent lodine 131") which is applicable in all modes. This deviation is acceptable.

Deviation #6 SS5-1 NUMARC/NESP-007 IC SS5 contains the following EALs:

4 Loss of reactor vessel water level as indicated by:

l - Loss of all decay heat removal cooling ....

and

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- (site-specific) Indicators that the core os or will be uncovered.

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5 The correspone"ng LGS EAL (2.1.3) reads as follows:

RPV[ReactorPressure Vessel] level <-161' The LGS EAL deviates by not including the condition cf the " loss of all decay heat removal cooling ...." This is acceptable because water level less than -172" (top of active fuel) is, by itseif, indication of the loss of decay heat removal.

Deviation #7 HA2-1 NUMARC/NESP-007 IC HA2 reads as follows-Fire or Explosion Affecting the Operability of Plant Safety Systems Required to Establish or Maintain Safe Shutdown.

The NUMARC/NESP-007 EAL under this IC reads as follows:

The following conditions exist:

a. Fire or explosion in any of the following (site-specific) areas:

(site-specific) list Alv0

b. Affected system parameter indications show degraded performance or plant j personnel report visible damage to permanent structures or equipment within the i specified area LGS developed the following EAL (8.2.2.a) for this condition:  !

Fire or explosion which potentially makes inoperable:

Two or more subsystems of a safe shutdown system (Table 8-2) or two or more safe shutdown systems orplant vital structures containing safe shutdown equipment and Safe shutc;own systems orplant vital structure is required for the present operationalcondition The licensee used the condition of "Two or more suosystems of a safe shutdown system (Table 8-2) or two or more safe shutdown systems..." at indication that the magnitude of the fire is such to cause a significant degradation in the level of safety of the plant. The condition

" Safe shutdown systems or plant vital structure is required for the present operational condition" is used as indication that the fire is located in an area which may cause a significant degradation in the level of safety of the plant. The LGS EAL meets the intent of the NUMARC/NESP-007 EAL, i.e., to classify fire-events which may cause a potential or actual substantial degradation in the level of safety of the plant. The site-specific indications used in the LGS EAL are intended to prevent classifying, as Alerts, fires whose magnitude or location

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6 does not result in a substantial degradation in the level of safety of the plant. This EAL is acceptable.

Site-soecific Indication #1 AS1-1, AG1-1 NUMARC/NESP-007 EAL AS1-1 reads as follows:

Valid dose assessment capability indicates dose consequences greater than 100 mR whole body or 500 mR child thyroid The licensee expresses its corresponding EAL (5.t3) in terms of Total Protective Action Recommendation Dose (TPARD) instead of the whole body dose specified in the NUMARC/NESP-007 guidance. TPARD is equal to Total Effective Dose Equivalent (TEDE) plus 4-day deposition dose and is equivalent to dose guidance in the Environmentai Protection Agency's Protective Action Guide' (EPA PAG). This is standard PECO Energy Company terminology and is included in the output of the computerized dose model MESOREM Jr. The LGS EAL meets the intent of the NUMARC/NESP-007 guidance and, therefore, is acceptable.

This also applies to licensee's EAL 5.1.4 (corresponding to NUMARC/NESP-007 EAL AG1-1).

Site-soecific Indication #2 AA3-2 NUMARC/NESP-007 IC AA3 reads as follows:

Release of Radioactive Material orIncreases in Radiation Levels Within the Facility That Impedes Operation of Systems Required to Maintain Safe Operations or to Establish or Maintain Cold Shutdown One of the example EALs under this IC (EAL AA3-2) reads as follows:

Valid (Site-specific) radiation monitor readings GREATER THAN < site-specific > values in areas requiring infrequent access to maintain plant safety functions.

The corresponding LGS EAL (5.2.2.a) reads as follows:

Valid radiation level readings >5000 mR/hr in areas requiring infrequent access to maintain plant safety functions as identifiedin procedure SE-1 or SE-6

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and Access is required for safe plant operation, but is impeded due to radiation dose rates The LGS EAL deviates from the NUMARC/NESP-007 example EAL oy including the condition

"and access is required for safe plant operation, but is impeded, due to radiation dose rates."

] However, this condition is included in the NUMARC/NESP 007 IC for this EAL and is included in

the basis for the EAL in the NUMARC/NESP-007 guidance. The LGS EAL is consistent with j the intent of the NUMARC/NESP-007 guidance and, therefore, is acceptable.

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! ' EPA Manual of Protective Action Guides and Protective Actions for Nuclear Incidents,

? EPA 400-R 92-001, May 1992 1

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7 Site-Soecific Indication #3 SUS NUMARC/NESP-007 EAL associated with IC SU5 reads as follows:

1. The fo!!owing conditions exist:

a. Unidentified or pressure boundary leakage greater than 10 gpm.

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b. Identified leakage greater than 25 gpm.

i The licensee's proposed EAL (2.1.1) reads as follows:

l The following conditions exist:

Unidentified Primary System Leakage > 10 gpm into the DryweII OR Identified Primary System Leakage > 25 ppm into the DryweII The proposed EAL appears to deviate from the corresponding NUMARC/NESP-007 EAL in that it does not refer to " pressure boundary leakage." The licensee indicated in its submittal that "There is no Limerick EAL listed for pressure boundary leakage specifically since it is a subset of unidentified leakage. Limerick Tech. Specs. requires a shutdown if any pressure boundary leakage is found." This is acceptable, in addition, the EAL includes the condition, " leakage ....

Into the drywel!," which is not specified in the NUMARC/NESP-007 guidance. Measurement of the magnitude of RCS leakage is from indications related to containment sump conditions.

Leakage outside of containment is identified from area temperatures or radiation monitors.

These indicators are used in EALs which are included in the fission product barrier matrix. The 1.GS EAL meets the intent of the NUMARC/NESP-007 guidance and, therefore, is acceptable.

_ Site-Soecific Indication #4 SA1-1 NUMARC/NESP-007 EAL SA1.1 reads as follows:

1. The following conditions exist:

a. Loss of power to (Site specific) transformem.

AND

b. Failure of (Site-specific) emergency generato= to supply porter to

! emergency busses.

AND s c. Failure to restore power to at least one emergency bus within 15 minutes l

from the time ofloss of both offsite and onsite AC pon ,r.

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l The LGS proposed EAL (6.1.2.b) reads as follows:

The following conditions exist:

Loss of Power to 101 and201 Safeguards Transformers dNE l Failure to restore power to at least One 4KV emergency bus within 15 minutes l from the time ofloss of both offsite and onsite AC power l LGS EAL deviates from the NUMARC/NESP-007 EAL in that it does not include the second  ;

condition of the NUMARC/NESP-007 EAL, which is "b. Failure of (Site-specific) emergency  ;

generators to supply power to emergency busses." However, the condition " Failure to restore power to at least One emergency bus within 15 minutes from the time of loss of both offsite and onsite AC power" can only occur if the emergency generators fail to supply power to the  ;

emergency buses. Therefore, the LGS EAL is consistent with the NUMARC/NESP-007 guidance and is acceptable.

Site-soecific Indication #5 SA3-1 NUMARC/NESP-007 EAL SA3-1 reads as follows: 1

1. The following conditions exist: l

a. Loss of (Site specific) Technical Spacification required functions to maintain cold shutdown.

AND

b. Temperature increase that either:

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• Exceeds Technical Specification cold shutdown temperature limit OR l

• Results in uncontrolled temperature rise approaching cold shutdown techn.2al specification limit.  :

The corresponding LGS EAL reads as follows:

Unplanned loss of all tech spec required systems available to proviu dc Jay heat removalfunctions l and Uncontrolled temperature increase that either;

- exceeds 200 'F (Excluding a <15 minute rise >200 *F with a heat removal function restored) or

- results in temperature rise approaching 200 'F (with no heat removal function restored)

The licensee included the conditions " Excluding a <15 minute rise >200 *F with a heat removal

! function restored" and "(with no heat removal function restored)" to prevent classifying events in L which systems can or have been restored in a short period of time to control RCS temperature.

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l Events where this restoration occurs do not warrant an Alert classification. Therefcre, this l deviation is acceptable.

Site soecific Addition #1 LGS added the following EAL (3.4 PC.5) to the fission product barrier as an indication of a potentialloss of the containment barrier:

! RPVlevelcannot be determined l and RPV Flooding cannot be establishedper T-116 The licensee added this EAL because under these conditions primary containment flooding j l would be necessary per their emeigency operating procedures and one of the actions taken as part of the primary containment flooding procedure is venting of containment. Furthermore, this I condition is indicative of a situation where the core cannot be adequately cooled such that a l core melt accident may be in progress. Therefore this condition is indicative of a potential loss of containment and this site-specific addition is acceptable.

Site-soecific Addition #2 LGS added the following EAL (3.3-RC.5) to the fission product barrlar as an indication of a potentialloss of the RCS barrier. I RPVlevelcannot be determined i The licensee added this EAL because there is a potential for this condition to exist during a loss of coolant accident due to boiling in the reactor level reference legs. The licensee provided clarification in the basis for this EAL to limit its applic,ation to these type of events. This site-specific addition is acceptable.

4.0 CONCLUSION

The proposed EAL chauges for LGS are consistent with the guidance in NUMARC/NESP-007, with variations as identified and accepted in this review, and, therefore meet the requirements of 10 CFR 50.47(b)(4) and Appendix E to 10 CFR Part 50.

Principal Contributor: J. O'Brien Date: March 11,.1999

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