United States Nuclear Regulatory Commission - Protecting People and the Environment

Request for Information Related to the Resolution of Generic Issue 130, & Essential Service Water System Failures at Multi-Unit Sites, & Pursuant to 10 CFR 50.54 (Generic Letter 91-13)


				                  UNITED STATES 
                          NUCLEAR REGULATORY COMMISSION
                             WASHINGTON D. C. 20555

                               September 19, 1991 


TO:       LICENSEES AND APPLICANTS OF THE FOLLOWING PRESSURIZED-WATER 
          REACTOR NUCLEAR POWER PLANTS:

               1.  Braidwood Units 1 and 2
               2.  Byron Units 1 and 2
               3.  Catawba Units 1 and 2
               4.  Comanche Peak Units 1 and 2
               5.  Cook Units 1 and 2
               6.  Diablo Canyon Units 1 and 2
               7.  McGuire Units 1 and 2

SUBJECT:  REQUEST FOR INFORMATION RELATED TO THE RESOLUTION OF GENERIC
ISSUE 130, "ESSENTIAL SERVICE WATER SYSTEM FAILURES AT MULTI-UNIT SITES,"
PURSUANT TO 10 CFR 50.54(f) - GENERIC LETTER 91-13  


DISCUSSION

The purpose of this letter is to inform affected licensees and applicants of 
the technical findings resulting from the NRC resolution of Generic Issue 
130 (GI-130), "Essential Service Water System Failures at Multi-Unit Sites," 
and to request information from licensees and applicants at affected 
multi-unit sites relating to the applicability of certain findings regarding 
their facilities.  Affected licensees and applicants are required to respond 
to the request for information contained in this letter, but no new 
requirements or staff positions are imposed on the affected licensees and 
applicants by this letter.  

The essential service water system (ESWS) is important in maintaining plant 
safety during power operation, shutdown, and accident conditions.  As part 
of our evaluation of loss of essential service water (LOSW), extensive 
analyses of this issue were performed at the Brookhaven National Laboratory 
(BNL).  The technical findings of this effort at BNL are reported in 
NUREG/CR-5526, "Analysis of Risk Reduction Measures Applied to Shared 
Essential Service Water Systems at Multi-Unit Sites."  In addition, the NRC 
staff performed a regulatory analysis to evaluate the safety benefits and 
implementation costs associated with various equipment and the 
administrative-type improvements that were considered.  The staff's 
regulatory analysis is contained in NUREG-1421, "Regulatory Analysis for the 
Resolution of Generic Issue 130:  Essential Service Water System Failures at 
Multi-Unit Sites."  These analyses assume that the flushing and flow testing 
provisions of Generic Letter (GL) 89-13, "Service Water System Problems 
Affecting Safety-Related Equipment," will be applied to the crosstie lines 
as part of addressees' implementation of the resolution of GI-51, "Improving 
the Reliability of Open-Cycle Service Water Systems" (GL 89-13 and 
Supplement 1).  On the basis of results of these evaluations of this generic 

.

Generic Letter 91-13                    -2-            September 19, 1991



safety issue, the NRC staff has concluded that the following 
administrative-type improvements would significantly enhance the 
availability of the ESWS in affected plants, and their implementation is 
warranted in view of the safety benefit to be derived and the cost of 
implementation:  

o    Technical specification (TS) changes contained in Enclosure 1 to 
     enhance the availability of the ESWS as applied to the design 
     configuration of affected plants.  

o    Improvement of emergency procedures for a LOSW using existing design 
     features, specifically:  (a) operating and maintaining high-pressure 
     injection (HPI) pump integrity in the event of loss of reactor coolant 
     pump (RCP) seals as a result of ESWS failure, and (b) testing and 
     manipulating the ESWS crosstie between the units during a LOSW 
     accident.

The incorporation of technical specification improvements is consistent with 
the Commission's Policy Statement on Technical Specification Improvements.  
This policy statement captures existing requirements under Criterion 3 
(Mitigation of Design-Basis Accidents or Transients) or under the provisions 

to retain requirements that operating experience and probabilistic risk 
assessment are shown to be important to the public health and safety.  
General Design Criteria 44, 45, and 46 of 10 CFR Part 50, Appendix A, in 
conjunction with the probabilistic risk assessment performed under GI-130, 
form the technical bases for these TS and procedures improvements.  

A backfit analysis of the type described in 10 CFR 50.109(a)(3) and 10 CFR 
50.109(c) was performed, and a determination was made that these new TS and 
procedures improvements would provide a substantial increase in overall 
protection of the public health and safety and that the costs of 
implementing these improvements are justified in view of this increased 
protection (Enclosure 2).  It should be noted that for the benefits of these 
improvements to be realized, the guidance contained in GL 89-13 and 
Supplement 1 should be considered in the context of the inter-unit crosstie.  
Namely, GL 89-13 states: "Redundant and infrequently used cooling loops 
should be flushed and flow tested periodically at the maximum design flow to 
ensure that they are not fouled or clogged.  Other components in the service 
water system should be tested on a regular schedule to ensure that they are 
not fouled or clogged...."

Enclosure 3 contains a discussion of an additional safety enhancement 
identified as part of our evaluation of GI-130 involving installation of a 
dedicated RCP seal cooling system similar to that identified also under 
GI-23, "Reactor Coolant Pump Seal Failures."  The final decision on the 
possible backfitting of additional plant improvements has been deferred 
until completion of GI-23; and that aspect of GI-130 is subsumed by GI-23.  
GI-23 will be resolved following the review of comments received based on 
the related Federal Register Notice published on April 19, 1991.  The 
comment period has been extended until September 30, 1991.  Enclosure 3 is 
provided to you for information only at this time.  

.

Generic Letter 91-13                  -3-              September 19, 1991



INFORMATION REQUEST (10 CFR 50.54(f))

Addressees are requested to review the recommended TS and procedures 
improvements described in the preceding discussion and to evaluate the 
applicability and safety significance of those improvements at their 
respective facilities.  On the basis of results of the recommended 
plant-specific evaluations, each addressee shall provide a response to the 
NRC pursuant to Section 182 of the Atomic Energy Act and 10 CFR 50.54(f) 
which indicates whether or not the recommended TS and procedures 
improvements are applicable to its facility, and whether or not the 
addressee will incorporate the TS (Enclosure 1) into its license and 
implement the procedures improvements.  The response shall be provided to 
the NRC under oath or affirmation within 180 days of the date of this 
letter.  If an addressee intends to implement the recommended TS and 
procedures improvements, the licensee shall include an implementation 
schedule as part of the response to this letter.  The licensee should retain 
supporting documentation consistent with the records retention program at 
each facility.  

An evaluation of the justification for this information request has been 
prepared in accordance with the requirements of 10 CFR 50.54(f).  That 
evaluation concludes that the information requested is justified in view of 
the potential safety significance of the ESW reliability issue to be 
addressed with that information (Enclosure 4).  Copies of NUREG-1421 and 
NUREG/CR-5526 are also enclosed for your information and to assist you in 
evaluating the applicability of this issue to your respective facilities 
(Enclosures 5 and 6).

A list of recently issued NRC GLs is enclosed for your information 
(Enclosure 7).

This request is covered by Office of Management and Budget Clearance Number 
3150-0011, which expires May 31, 1994.  The estimated average burden hours 
is 50 person hours per owner response, including assessment of the new 
recommendations, searching data sources, gathering and analyzing the data, 
and preparing the required letters.  These estimated average burden hours 
pertain only to the identified response-related matters and do not include 
the time for actual implementation of the requested action.  Send comments 
regarding this burden estimate or any other aspect of this collection of 
information, including suggestions for reducing this burden, to the 
Information and Records Management Branch (MNBB-7714), Division of 
Information Support Services, Office of Information Resources Management, 
U.S. Nuclear Regulatory Commission, Washington, D.C.  20555; and to Ronald 
Minsk, Office of Information and Regulatory Affairs (3150-0011), NEOB-3019, 
Office of Management and Budget, Washington, D.C.  20503. 
.

Generic Letter 91-13                  -4-              September 19, 1991



If you have any questions on this matter, please contact your Project 
Manager.  

                                   Sincerely, 
                                   
                                   James G. Partlow
                                   Associate Director for Projects 
                                   Office of Nuclear Reactor Regulation

Enclosures: 1.  Draft Technical 
    Specifications (3/4.7.4) 2.  Backfit Analysis for GI-130 
3.  Background Discussion of 
    a Deferred Safety Enhancement 
    from GI-130 to GI-23 
4.  Justification Analysis  
    [10 CFR 50.54(f)] for Generic Letter on GI-130 
5.  NUREG-1421 
6.  NUREG/CR-5526 
7.  List of Recently Issued NRC 
    Generic Letters 
.

                                   ENCLOSURE I

                          DRAFT TECHNICAL SPECIFICATION


PLANT SYSTEMS

3/4.7.4 SERVICE WATER SYSTEM

LIMITING CONDITION FOR OPERATION                                           

3.7.4  At least two independent service water loops per unit and the 
crosstie between the service water systems of each unit (as applicable) 
shall be operable.  In addition, the crosstie shall be capable of being 
opened [from the main control room] as a flow path between the two units.  

APPLICABILITY:  Modes 1, 2, 3, and 4.  

ACTION:

A.   Both units in Modes 1, 2, 3, or 4.  

     With one service water loop per unit OPERABLE, restore at least two 
     loops per unit to OPERABLE status within 72 hours, or for the unit with 
     the inoperable service water loop, be in at least HOT STANDBY within 
     the next 6 hours and in COLD SHUTDOWN within the following 30 hours.  

     2.   With one [or both] of the crosstie valve(s) INOPERABLE and not 
          capable of being opened [from the control room], within 72 hours 
          restore the valve(s) to OPERABLE status or open the affected 
          valve(s), and maintain the affected valve(s) open; otherwise be in 
          at least HOT STANDBY within the next 6 hours and in COLD SHUTDOWN 
          within the following 30 hours.  

B.   One unit in Modes 1, 2, 3, or 4 and one unit in Mode 5 or 6.

     1.   Verify that at least one pump in the shut down unit is OPERABLE 
          and available to provide service water to the operating unit.  If 
          neither service water pump in the shut down unit is OPERABLE, 
          restore at least one pump to OPERABLE status within 72 hours, or 
          place the operating unit in at least HOT STANDBY within the next 6 
          hours and in COLD SHUTDOWN within the following 30 hours.  

     2.   With one service water loop in the operating unit INOPERABLE, 
          restore two loops in the operating unit to OPERABLE status within 
          72 hours or be in at least HOT STANDBY within the next 6 hours and 
          in COLD SHUTDOWN within the following 30 hours.  

     3.   With one [or both] of the crosstie valve(s) INOPERABLE and not 
          capable of being opened [from the control room], within 72 hours 
          restore the valve(s) to OPERABLE status or open the affected 
          valve(s), and maintain the affected valve(s) open; otherwise be in 
          at least HOT STANDBY within the next 6 hours and in COLD SHUTDOWN 
          within the following 30 hours.  

.

DRAFT TECHNICAL SPECIFICATIONS


PLANT SYSTEMS

SURVEILLANCE REQUIREMENTS                                                   

4.7.4 Two service water loops per unit shall be demonstrated OPERABLE:  

      a.  At least once per 31 days by verifying that each valve (manual, 
          power-operated, or automatic) servicing safety-related equipment 
          that is not locked, sealed, or otherwise secured in position is in 
          its correct position.

      b.  At least once per 92 days by cycling crosstie valves and/or 
          verifying that valves are locked open with power removed; and

      c.  At least once per 18 months during shutdown, by verifying that:  

          1.  Each automatic valve servicing safety-related equipment 
              actuates to its correct position on a test signal; 

          2.  Each service water system pump starts automatically on a
              test signal; and 

          3.  Each crosstie valve is cycled or is locked open with power 
              removed. 

BASES                                                                       

3/4.7.4 SERVICE WATER SYSTEM

The OPERABILITY of the service water system ensures that sufficient cooling 
capacity is available for continued operation of safety-related equipment 
during normal and accident conditions.  The redundant cooling capacity of 
this system, assuming a single failure, is consistent with the assumptions 
used in the accident conditions within acceptable limits.  

In the event of a total loss of service water in one unit of a two-unit site 
where backup cooling capacity is available via a crosstie between the two 
units, the OPERABILITY of the unit crosstie along with a service water pump 
in the shut down unit ensures the availability of sufficient redundant 
cooling capacity for the operating unit.  These limiting conditions will 
ensure a significant risk reduction, as indicated by the analyses of a 
loss-of-service water system accident.  The surveillance requirements ensure 
the short-term and long-term operability of the service water system and the 
crosstie between the two units.  The service water system crosstie between 
the two units consists of appropriate piping, valves, and instrumentation 
cross-connecting the discharge of the service water pumps of the two units.  
By operating the crosstie, the supply of additional redundant cooling 
capacity from one unit is available to the service water system of the other 
unit.  
.

                                   ENCLOSURE 2

                   BACKFIT ANALYSIS (REFERENCE 10 CFR 50.109)

                              FOR GENERIC ISSUE 130


A.1 INTRODUCTION

This enclosure presents the backfit analysis for Generic Issue 130 (GI-130), 
"Essential Service Water System Failures at Multi-Unit Sites."  The 
technical findings for GI-130 are presented in NUREG/CR-5526, and the 
regulatory analysis is presented in NUREG-1421.  The studies apply to 14 
reactor units at seven sites and indicate that essential service water 
system (ESWS) failures at these plants are a significant contributor to the 
overall plant risk.  As a consequence of these technical findings, and based 
on the cost/benefit analyses performed, the staff has determined that these 
14 plants may need to modify technical specifications (TS) to enhance the 
availability of the ESWS and to institute procedures to assure the integrity 
of the high-pressure injection (HPI) pump in the event of RCP seal failure 
as a result of loss of essential service water (LOSW), as well as procedures 
to test and manipulate the ESWS crosstie between the two units during a LOSW 
accident.  

The estimated benefit from the identified safety enhancements is a reduction 
in the core damage frequency and a reduction in the associated risk of 
offsite radioactive releases as a result of ESW failure.  The reduction of 
risk to the public (per plant lifetime) is estimated to be 4141 person-rem 
(best estimate numbers used) and supports the conclusion that these safety 
enhancements provide a substantial increase in the overall protection of the 
public health and safety.  Also, the direct and indirect costs of 
implementation are justified in view of this increased protection.  

As discussed in NUREG-1421, when considered individually, most of the 
alternatives analyzed for reducing the risk associated with this issue would 
be cost-effective in meeting the $1000/person-rem guideline.  The objective 
of the GI-130 resolution is that the risk from loss of the ESWS be reduced 
consistent with the two basic requirements of the backfit rule that the 
corrective alternatives be both substantial and cost-effective.  

One of the potential improvements consisting of improvements in TS and 
emergency procedures was shown to be capable of reducing the core damage 
frequency (CDF) from loss of ESW (1.5E-04/RY) by 17 percent (or by 
approximately 3.0E-05/RY) in a cost-effective manner.  The staff recognizes 
the uncertainties in these estimates, and in recognition of the potentially 
substantial risk reductions (over 4000 person-rem per plant lifetime), the 
staff believes that significant safety improvements can be achieved by low 
cost changes in TS and procedures.  This is deemed to be consistent with the 
provisions of the backfit rule.  

The overall approach to arriving at the proposed resolution considered both 
the numerical results of the cost-benefit analysis and the spectrum and type 
of potential improvements available for potential risk reduction for 
.

loss-of-service-water sequences.  Those alternatives that could reduce the 
number of occurrences of the LOSW initiators would be desirable from the 
prevention perspective.  Those alternatives that would help to reduce the 
consequences of an LOSW would be desirable from the mitigation perspective.  
The improvements in the TS would assist on the prevention side, while the 
improved procedures would provide a blend of both prevention and mitigation 
capabilities.  

The conclusion of this backfit analysis is that a substantial increase in 
the protection of the public health and safety will be derived from 
backfitting of the ESWS improvements and that the backfit is justified in 
view of the favorable cost/benefit ratios.  In the following sections of 
this backfit analysis, the nine factors stipulated by 10 CFR 50.109(c) to be 
used in the determination of backfitting are addressed.  

A.2  ANALYSIS OF 10 CFR 50.109(c) FACTORS FOR "ALTERNATIVE 5"

A.2.1  Objective

The objective of Alternative 5 (the proposed backfit) is to improve the 
performance of the ESW system by providing a blend of both prevention and 
mitigation capabilities.  This backfit will be applicable to all the 
pressurized-water reactor (PWR) plants (14 units) covered by GI-130.  

A.2.2  Licensee Activities

To implement "Alternative 5," each licensee would modify TS in accordance 
with Enclosure 1 to this generic letter, as well as implement procedures for 
operating and maintaining HPI pump integrity and testing and manipulating 
the ESWS crosstie between units during a LOSW event.  

A.2.3  Public Risk Reduction

Backfitting in accordance with the proposed alternative will yield a 
reduction in the incidence of public risk from the accidental offsite 
release of radioactive materials of 4141 person-rem (best-estimate) per 
plant with an average remaining life of 30 years.  This backfit will reduce 
the core damage frequency from an LOSW by 17 percent (or by approximately 
3.0E-05/RY).  

As detailed in Chapter 6 of NUREG-1421, the staff recognizes the 
uncertainties in these estimates and has considered both the numerical 
results of the cost-benefit analysis as well as the spectrum and type of 
potential improvements for risk reductions associated with LOSW sequences.  

A.2.4  Occupational Exposure

The radiological operational exposure is negligible and, therefore, the 
implementation of Alternative 5 will not result in any increase in the 
radiological exposure to facility employees.  

.

A.2.5  Installation Costs

The best estimate total cost per reactor associated with Alternative 5 is 
$83,000.  When the onsite averted costs are taken into account, this 
alternative results in a net savings.  

A.2.6  Potential Safety Impact

A number of generic safety issues related to GI-130 have been in various 
stages of resolution, including some that have already been resolved.  The 
relation of these issues to GI-130 is as follows:  

     o    GI-23, "Reactor Coolant Pump Seal Failures" -- This generic safety 
          issue addresses the same possible improvements as Alternative 6 
          and, in part, Alternative 7 of GI-130.  The staff's current 
          understandings, technical findings, and potential recommendations 
          regarding GI-23 were issued for public comment.  On the basis of 
          the staff's current knowledge and perspective, the staff has 
          identified an approach for the resolution of GI-23.  This approach 
          is contained in Draft Regulatory Guide DG-1008.  

          An objective of the identified approach for the resolution of 
          GI-23 is to reduce the risk of severe accidents associated with 
          RCP seal failure by reducing the probability of seal failure, or 
          to demonstrate that the risk is not significant, thus assuring 
          that it is a relatively small contributor to total core damage 
          frequency.  The proposed means of doing so entails the 
          installation of a separate and independent cooling system for the 
          RCP seals.  Hence, implementation of the proposed GI-23 resolution 
          could provide a substantial portion of the proposed GI-130 
          resolution.  As such, the resolution of GI-130 is coordinated with 
          the resolution of GI-23 by allowing the installation of a backup 
          RCP seal cooling system to be deferred to the resolution of GI-23 
          pending the receipt and review of public comments.  It is expected 
          that information developed as a result of the submittal of public 
          comments will be helpful in our efforts to better understand the 
          performance of the RCP seals under loss of seal cooling 
          conditions.  

     o    GI-51, "Improving the Reliability of Open-Cycle Service-Water 
          Systems" -- The resolution of this generic safety issue was 
          reported in August 1989 and its imposition began with the issuance 
          of Generic Letter 89-13 and Supplement 1.  Implementation of the 
          GI-51 entails the implementation of a series of surveillance, 
          control, and test requirements to ensure that the ESWS of all 
          nuclear power plants are in compliance with all applicable 
          licensing requirements.  

          During the review of the operational experience data of GI-130, 
          credit was taken for a corrective measure as a result of the 
          resolution of GI-51 by excluding those events that involved 
          biofouling of the ESW.  Hence, GI-51 has no direct impact on 
          GI-130.  

.

     o    GI-153, "Loss of Essential Service Water in LWRs" has been 
          assigned NRC staff resources for its resolution.  Its purpose is 
          to assess this issue for all light-water reactors (LWRs) not 
          already covered by GI-130.  Insights gained by the evaluation of 
          GI-153 are expected to be useful in confirming and/or 
          supplementing the technical findings of GI-130.  

Of interest to the decision process on this generic issue are the insights 
and reviews available in related probabilistic risk assessment (PRA) 
documentation in the open literature.  The PRA work available in NUREG-1150, 
"Severe Accident Risks:  An Assessment for Five U.S. Nuclear Power Plants" 
(plus supporting documentation) is a source of extensive risk analyses 
information that might be used for an understanding of ESW vulnerabilities.  
An examination of the NUREG-1150 documentation of the three PWRs that were 
studied indicates that the analyst thought that the ESW redundancy for two 
of the three PWRs was large enough that a complete loss of ESW as an event 
initiator was deemed not credible (eight pumps are available at Sequoyah, 
Units 1 and 2).  None of the five plants in the NUREG-1150 study is a GI-130 
plant; however, it is worthwhile to note that one of the PWRs (Zion) 
identified the service water contribution to CDF to be substantial 
(approximately 1.5E-04/RY).  This contribution for Zion was approximately 42 
percent of the total core damage frequency from all causes.  

Another PRA work available in the open literature is NSAC-148, "Service 
Water Systems and Nuclear Plant Safety," dated May 1990.  Although NSAC-148 
is only a compilation of earlier PRA results for six plants performed by the 
industry, it is useful to note that a greater appreciation of the service 
water system's contribution to plant risk has moved the industry to initiate 
a program to improve service water performance.  The limited guidance 
available in NSAC-148 is a step in the right direction.  The wide range of 
core damage frequencies (from LOSW) at the six plants studied suggests the 
large variability in plant-specific ESW configurations.  The average CDF 
from LOSW for the six plants was 6.55E-05/RY, with a range of 
2.33E-04/RY-to-"negligible" contribution.  Although many details of these 
six PRAs are not included in NSAC-148, and therefore, must be considered to 
be used only with great caution, the overall message that the service water 
system provides an important safety function that could be a substantial 
contributor to overall plant risk tends to lend added credence to the GI-130 
conclusions.  

A.2.7  NRC Costs

Implementation of Alternative 5 is estimated at $21,000 (best estimate).  
This estimate assumes minimal resources for review of the generic letter 
responses.  

A.2.8  Facility Differences

Alternative 5 is applicable to all 14 plants covered by this study, 
regardless of age or design.  Other PWR and BWR plants that are not included 
under the resolution of GI-130 will be evaluated under GI-153, "Loss of 
Essential Service Water in LWRs."  
.


A.2.9  Term of Requirements

This represents the final resolution of GI-130.  Alternative No. 6 entailing 
the installation of an independent RCP seal cooling system has been subsumed 
under the resolution of GI-23.  
.

                                  ENCLOSURE 3 

             BACKGROUND DISCUSSION OF A DEFERRED SAFETY ENHANCEMENT 

                              FROM GI-130 TO GI-23 

             (INSTALLATION OF A DEDICATED RCP SEAL COOLING SYSTEM) 


As identified in NUREG-1421, "Regulatory Analysis for the Resolution of 
Generic Issue 130:  Essential Service Water System Failures at Multi-Unit 
Sites," a combination of potential improvements consisting of the 
installation of a backup, dedicated RCP seal cooling system, and 
improvements in technical specifications (TS) and procedures are shown to be 
capable of substantial risk reduction.  The specific features of such a 
backup, dedicated RCP seal cooling system would be as follows:  

     o    Single high pressure pump, 50-100 gpm capacity 

     o    Dedicated water storage tank with capacity to last at least 8-10 
          hours 

     o    AC-independent (non-seismic) pump 

     o    No support system cooling required 

     o    Once-through RCP seal heat removal  

Limited plant-specific information obtained through the existing literature 
(FSARs, and so forth), site visits, or discussions with licensees have 
indicated that a number of the units covered by GI-130 already have 
plant-unique features that could be responsive to this generic safety 
enhancement.  Rather than attempting to perform a series of PRAs tailored to 
each of the 14 units, the NRC encourages each licensee or applicant to 
review the plant-specific features (if any) that could be credited with 
departing from the generic (representative) base case plant configuration 
modelled in NUREG/CR-5526.  In addition, other design alternatives may also 
be considered utilizing arrangements different from that of the 
high-pressure pump seal injection.  

One such alternative would provide flow through the RCP thermal barrier heat 
exchangers by connecting the fire water system into the component cooling 
water (CCW) lines.  Most fire water systems have one diesel-driven fire 
water pump, which usually is independent of the ESWS.

Generic Issue 23, "Reactor Coolant Pump Seal Failures," deals with this 
recommendation also, and specific guidance for resolving that generic issue 
is given in proposed Regulatory Guide DG-1008.  While awaiting completion of 
public review and comment on draft Regulatory Guide DG-1008, resolution of 
this GI-130 item has been deferred until GI-23 is resolved.  The reason for 
this deferral relates to the earlier development and promulgation of 10 CFR 
50.63 (station blackout rule), which was based on an assumption regarding 
the magnitude of RCP seal leakage during a station blackout event.  While it 
was 

.

                                      - 2 -


left to GI-23 to validate that assumption, the resolution of GI-130 is also 
based on a RCP seal failure LOCA model very similar to that of GI-23, but 
different from the leakage assumption in 10 CFR 50.63.  
.

                                  ENCLOSURE 4 

                    JUSTIFICATION ANALYSIS [10 CFR 50.54(f)] 

                    FOR GENERIC LETTER ON GENERIC ISSUE 130 


Section 50.54(f) of 10 CFR Part 50 requires that "... the NRC must prepare 
the reason or reasons for each information request prior to issuance to 
ensure that the burden to be imposed on respondents is justified in view of 
the potential safety significance of the issue to be addressed in the 
requested information."  Further, Revision 4 of the Charter of the Committee 
To Review Generic Requirements (CRGR), dated April 1989, specifies that, at 
a minimum, such an evaluation shall include the following:

     a.   A problem statement that describes the need for the information in 
          terms of potential safety benefit,

     b.   The licensee actions required and the cost to develop a response 
          to the information request, and

     c.   An anticipated schedule for NRC use of the information.

The staff's 10 CFR 50.54(f) evaluation of the information request addressing 
the above elements follows:

     a.   Problem Statement That Describes the Need for the Information in 
          Terms of Potential Safety Benefit

          The recommended resolution of Generic Issue 130 (GI-130), 
          "Essential Service Water System Failures at Multi-Unit Sites," 
          applies to 14 reactor units at seven sites and indicates that 
          essential service water system (ESWS) failures at these plants may 
          significantly contribute to the overall plant risk.  As a 
          consequence of these technical findings, and based on the 
          cost/benefit analyses performed, the staff has determined that 
          these 14 plants may need to modify technical specifications (TS) 
          to enhance the availability of the ESWS and to institute 
          procedures to assure the integrity of the HPI pump in the event of 
          RCP seal failure as a result of loss of essential service water 
          (LOSW), as well as procedures to test and manipulate the ESWS 
          crosstie between the two units during a LOSW accident.

          The estimated benefit from the identified safety enhancements is a 
          reduction in the core damage frequency and a reduction in the 
          associated risk of offsite radioactive releases as a result of ESW 
          failure.  The reduction of risk to the public (per plant lifetime) 
          is estimated to be 4141 person-rem (best estimate numbers used) 
          and supports the conclusion that these safety enhancements provide 
          a substantial increase in the overall protection of the public 
          health and safety.  Also, the direct and indirect costs of 
          implementation are justified in view of this increased protection.  
          The staff recognizes the uncertainties in these estimates, and in 
          recognition of the potentially substantial risk reductions, the 
          staff believes that significant safety improvements can be 
          achieved by low cost changes in TS and procedures, consistent with 
          the provisions of the backfit rule.
.

          As discussed in NUREG-1421, when considered individually, most of 
          the alternatives analyzed for reducing the risk associated with 
          this issue would be cost-effective in meeting the $1000/person-rem 
          guideline.  The objective of the GI-130 resolution is that the 
          risk from the loss of the ESWS be reduced consistent with the two 
          basic requirements of the backfit rule that the corrective 
          alternatives be both substantial and cost-effective.

          One of the potential improvements consisting of improvements in TS 
          and emergency procedures was shown to be capable of reducing the 
          CDF as a result of loss of ESW (1.5E-04/RY) by 17 percent (or by 
          approximately 3.0E-05/RY) in a cost-effective manner.  As 
          discussed earlier, this is deemed to be consistent with the 
          provisions of the backfit rule.

          The overall approach to arriving at the proposed resolution 
          considered both the numerical results of the cost-benefit analysis 
          and the spectrum and type of potential improvements available for 
          potential risk reduction for loss-of-service-water sequences.  
          Those alternatives that could reduce the number of occurrences of 
          the LOSW initiators would be desirable from the prevention 
          perspective.  Those alternatives that would help to reduce the 
          consequences of a LOSW would be desirable from the mitigation 
          perspective.  The improvements in the TS would assist on the 
          prevention side, while the improved procedures would provide a 
          blend of both prevention and mitigation capabilities.

          The conclusion of our analysis is that a substantial increase in 
          the protection of the public health and safety will be derived 
          from the improvements in the TS and procedures, which are 
          justified by the favorable cost/benefit ratio.  Hence, in view of 
          the safety significance of the recommended resolution of GI-130, 
          the issuance of this generic letter under 10 CFR 50.54(f) is 
          justified.  (See also Item b. below.)

     b.   The Licensee Response Required and the Cost to Develop the  
          Responseto the Information Request
       
          All the recipient licensees or applicants of this generic letter 
          would be requested to review the TS and procedures improvements 
          identified as part of our evaluation of GI-130 and to assess the 
          applicability of these improvements to their respective 
          facilities. 

          We estimate that the cost of reviewing and evaluating the contents 
          of this generic letter and preparing a response will cost no more 
          than $2500 per licensee or applicant.  It is expected that this 
          cost may 
          .          
          
          vary from site to site, depending on the degree to which the TS 
          and procedures improvements apply to individual plants.  This cost 
          is insignificant compared to the cost-justified improvements (see 
          cost estimates presented in NUREG-1421), which represent a 
          substantial safety improvement.  

     c.   An Anticipated Schedule for the NRC Use of the Information
          
          We expect that the responses to this generic letter would be 
          submitted within the 180-day schedule required by the generic 
          letter, and that NRC staff review of the responses will be 
          completed within 180 days from their receipt.  

Page Last Reviewed/Updated Friday, June 28, 2013