United States Nuclear Regulatory Commission - Protecting People and the Environment


ACCESSION #:   9707290132



Charles H. Cruse                   Baltimore Gas and Electric Company

Vice President                     Calvert Cliffs Nuclear Power Plant

Nuclear Energy                     1650 Calvert Cliffs Parkway

                                   Lusby, Maryland 20657

                                   410 495-4455



BGE

                         July 22, 1997



U. S. Nuclear Regulatory Commission

Washington, DC 20555



ATTENTION:     Document Control Desk



SUBJECT:       Calvert Cliffs Nuclear Power Plant

               Unit Nos. 1 & 2; Docket Nos. 50-317 & 50-318

               10 CFR Part 21 Report Concerning Failure of Main Steam

               Header Radiation Monitors Supplied by Nuclear Research

               Corporation



Baltimore Gas and Electric Company has recently experienced failures of

the new vendor supplied Main Steam Header Radiation Monitors at our

Calvert Cliffs Nuclear Power Plant Unit Nos. 1 and 2.  The failures

resulted from a defect in an installed basic component that could have

created a substantial safety hazard at our facility and is reportable in

accordance with 10 CFR Part 21 requirements.  The defect has been

identified with the detector temperature compensation circuit for these

radiation monitors that resulted in the inability of these safety-related

components to perform their intended function.  The Unit 1 and Unit 2

Main Steam Header Radiation Monitors are currently inoperable; however,

the alternate preplanned monitoring method has been implemented.



A verbal initial notification and facsimile were submitted to the Nuclear

Regulatory Commission Operations Center on July 14, 1997.



Should you have questions regarding this matter, we will be pleased to

discuss them with you.



                              Very truly yours,



CHC/RCG/bjd



Attachment



cc:  R. S. Fleishman, Esquire           H. J. Miller, NRC

     J. E. Silberg, Esquire             Resident Inspector, NRC

     A. W. Dromerick, NRC               R. I. McLean, DNR

     Director, Project Directorate

     I-1, NRC                           J. H. Walter, PSC



                             ATTACHMENT (1)



               10 CFR PART 21 REPORT CONCERNING FAILURE OF

                  MAIN STEAM HEADER RADIATION MONITORS

                SUPPLIED BY NUCLEAR RESEARCH CORPORATION



Calvert Cliffs Nuclear Power Plant, Units 1 and 2



Docket Nos: 50-317 and 50-318



(i)       Name and Address of Individual Making Notification:



          C. H. Cruse, Vice-President, Nuclear Energy Division

          Baltimore Gas and Electric Company

          Calvert Cliffs Nuclear Power Plant

          1650 Calvert Cliffs Parkway

          Lusby, MD 20657



(ii)      Basic Component Affected:



          Nuclear Research Corporation Extended Range Gamma Scintillation

          Detector MD-55E(V3)



(iii)     Firm Supplying Component.



          Nuclear Research Corporation

          125 Titus Avenue

          Warrington, PA 18976



(iv)      Nature of the Defect.



          The Main Steam Header Radiation Monitor detectors are located

          in the Main Steam Isolation Valve (MSIV) room.  The detectors

          are mounted adjacent to their respective main steam line, close

          to the containment penetration, upstream of the Main Steam

          Safety Valves (MSSVs).  The Main Steam Header Radiation

          Monitors are designed to measure potential noble gas releases

          to the environment in the event of primary-to-secondary steam

          generator tube leakage concurrent with lifting of the MSSVs,

          atmospheric dump valves or the exhaust from the turbine-driven

          auxiliary feedwater pumps.  The purpose of the Main Steam

          Header Radiation Monitors is to detect significant radiological

          releases and provide meaningful release information for offsite

          emergency actions.



          If a Main Steam Header Radiation Monitor is inoperable, then in

          accordance with Technical Specification 3.3.3.1, Action

          Statement (30) and the Emergency Response Plan Implementation

          Procedures, the preplanned alternate method of monitoring

          effluent noble gas in the respective main steam header is

          implemented.



          The Unit Nos. 1 and 2 safety-related Main Steam Header

          Radiation Monitors were recently replaced in accordance with

          approved modifications.  The Unit 1 radiation monitors were

          tested



                                    1



                             ATTACHMENT (1)



               10 CFR PART 21 REPORT CONCERNING FAILURE OF

                  MAIN STEAM HEADER RADIATION MONITORS

                SUPPLIED BY NUCLEAR RESEARCH CORPORATION



          and declared OPERABLE in early May 1997.  The Unit 2 radiation

          monitors were tested and declared OPERABLE in late May 1997.

          In early June 1997, the Unit 1 Main Steam Header Radiation

          Monitors successfully passed their first monthly channel

          functional surveillance tests required by Technical

          Specification 3.3.3.1.  On June 6, 1997, during performance of

          their first monthly channel functional test, Unit 2 Main Steam

          Header Radiation Monitors Nos.  21 and 22 failed to respond

          during a checksource test, were declared not OPERABLE, and the

          alternate preplanned monitoring method was implemented.  On

          June 10, 1997, following evaluation of troubleshooting results

          on the Unit 2 Main Steam Header Radiation Monitor detectors,

          confirmatory tests performed on the Unit 1 Nos. 11 and 12 Main

          Steam Header Radiation Monitors revealed that they also failed

          to respond during a checksource test.  These Unit I radiation

          monitors were removed from OPERABLE status, and the alternate

          preplanned monitoring method was implemented.



          Although the inoperability of Nos. 11 and 12 (Nos. 21 and 22)

          Main Steam Header Radiation Monitors has not affected Unit 1

          (Unit 2) operation, the detectors failed to operate as expected

          over the required temperature range.  This defect resulted in

          the inability of these safety-related components to perform

          their intended function (i.e., detect significant radiological

          releases and provide meaningful release information for offsite

          emergency actions).  The Main Steam Header Radiation Monitors

          are passive monitoring instrumentation that do not interface

          with any other safety-related equipment.  However, these

          radiation monitors are designated safety-related and are

          designed to be operational during and following the event.  The

          details of the discovery and nature of the defect are provided

          below.



          Numbers 21 and 22 Main Steam Header Radiation Monitors were

          replaced per an approved modification during the Unit 2 spring

          1997 refueling outage.  Following the installation, Engineering

          Test Procedures were performed which included the performance

          of checksource tests.  The monitors satisfactorily passed all

          requirements of the Engineering Test Procedures (performed with

          Unit 2 in MODE 5 and a MSIV room ambient temperature of

          approximately 90 degrees F) and were placed in an OPERABLE

          status in late-May 1997.



          On June 6, 1997, during the performance of the first monthly

          channel functional test required by Unit 2 Technical

          Specifications surveillance requirements, Nos. 21 and 22 Main

          Steam Header Radiation Monitors failed to respond during the

          checksource test.  The radiation monitor was removed from

          OPERABLE status and the alternate preplanned monitoring method

          was implemented.  Troubleshooting on No. 21 Main Steam Header

          Radiation Monitor determined that the checksource was properly

          aligned with respect to the collimating hole during the

          checksource test.  However, no response from the detector was

          noted during subsequent checksource tests.  Further

          troubleshooting found that no response was seen when the

          checksource was placed directly on the detector.  Satisfactory

          source strength of the checksource was confirmed by placing it

          directly on a personnel contamination gamma detector.  Several

          checksource tests were then performed on No.  22 Main Steam

          Header Radiation Monitor and no detector response was noted.



          During evaluation of the troubleshooting results above, it was

          suspected that a generic problem may exist with detector

          performance.  Therefore, on June 10, 1997, confirmatory

          checksource tests were performed on the similar Unit 1 Nos. 11

          and 12 Main Steam Header Radiation



                                    2



                             ATTACHMENT (1)



               10 CFR PART 21 REPORT CONCERNING FAILURE OF

                  MAIN STEAM HEADER RADIATION MONITORS

                SUPPLIED BY NUCLEAR RESEARCH CORPORATION



          Monitors.  Both Unit 1 radiation monitors failed to respond to

          a checksource test and were removed from OPERABLE status.  The

          alternate preplanned monitoring method was implemented.  [Note:

          The Unit 1 Main Steam Header Radiation Monitors were replaced

          earlier in 1997 per an approved modification.  These new Unit 1

          radiation monitors were tested satisfactorily (with Unit 1

          operating in MODE 1 and MSIV room ambient temperature

          approximately 110 degrees F-120 degrees F), in accordance with

          similar Engineering Test Procedures as those performed on the

          Unit 2 Main Steam Header Radiation Monitors.  The Unit 1 Nos.

          11 and 12 Main Steam Header Radiation Monitors were placed in

          an OPERABLE status in early-May 1997.  These Unit 1 radiation

          monitors satisfactorily completed their first monthly channel

          functional test required by Technical Specification

          surveillance requirements earlier in June 1997.  The MSIV room

          ambient temperature was still approximately 110 degrees F-120

          degrees F.]



          Following confirmation that a generic detector performance

          problem existed, additional troubleshooting (using No.  21 Main

          Steam Header Radiation Monitor) determined that the detectors

          were sensitive to elevated temperatures.  With MSIV room

          ambient temperature measured at approximately 135 degrees F, a

          contact temperature reading on No. 21 Main Steam Header

          Radiation Monitor detector measured approximately 155 degrees

          F.  This detector was removed from the Unit 2 MSIV room,

          allowed to cool to approximately 80 degrees F, and was returned

          to the MSIV room.  A checksource test was immediately performed

          with satisfactory results.  However, subsequent checksource

          tests, performed at approximately 3 to 5 minute intervals,

          showed a degrading detector performance.



          Checks utilizing secondary calibration button check sources

          were performed on No. 21 Main Steam Header Radiation Monitor

          detector after cooling the detector to approximately 80 degrees

          F, with the detector at a MSIV room ambient temperature of 135

          degrees F, and with the detector at approximately 155 degrees

          F.  Degraded detector performance was noted at the elevated

          temperatures.



          Vendor documentation states that this detector should be

          capable of operating satisfactorily over a temperature range of

          -22 degrees F to +194 degrees F.  Vendor environmental test

          data appeared to substantiate the published detector operating

          temperature range.  However, based upon the results of the

          troubleshooting and the vendor specifications, it was concluded

          that the detectors were not operating as expected over the

          required temperature range.  The cause of the inoperability of

          the Main Steam Header Radiation Monitors was determined to be

          inadequate vendor design of the detector temperature

          compensation circuit.  Baltimore Gas and Electric Company (BGE)

          design specification for the new safety-related Main Steam

          Header Effluent Monitors requires that these detectors be able

          to operate at a continuous temperature of 170 degrees F.  In

          addition, the design specifications state that these radiation

          monitors shall meet the requirements of Regulatory Guide 1.97,

          Table 3, Category 2, Type E Variable, "Vent From Steam

          Generator Safety Relief Valves or Atmospheric Dump Valves," in

          which a Type E Variable is defined as those variables to be

          monitored as required for use in determining the magnitude of

          the release of radioactive materials and continually assessing

          such releases.  The design specifications define the safety

          classification of the Main Steam Header Radiation Monitors

          stating, in part, that all safety-related equipment must be

          manufactured and procured under a 10 CFR Part 50, Appendix B

          program and that the requirements of 10 CFR Part 21 apply.



                                    3



                             ATTACHMENT (1)



               10 CFR PART 21 REPORT CONCERNING FAILURE OF

                  MAIN STEAM HEADER RADIATION MONITORS

                SUPPLIED BY NUCLEAR RESEARCH CORPORATION



(v)       Date on Which Defect Was Identified.



          On June 6, 1997, Issue Reports were written documenting that

          Nos. 21 and 22 Main Steam Header Radiation Monitors had failed

          their checksource tests during surveillance testing and were

          declared not OPERABLE.  On June 10, 1997, an Issue Report was

          written documenting that the Unit 1 Main Steam Header Radiation

          Monitors had failed the requested checksource tests (and

          declared not OPERABLE) that were performed due to the generic

          concern with all the Main Steam Header Radiation Monitors.  On

          July 1, 1997, we submitted a Special Report to the Nuclear

          Regulatory Commission concerning the inoperability of the Unit

          1 and Unit 2 Main Steam Header Radiation Monitors discussed

          above.  The extent of the deviation (i.e., departure from the

          design specification that the detectors be able to operate at a

          continuous temperature of 170 degrees F) that resulted in the

          failed surveillance testing and inoperability of the Main Steam

          Header Radiation Monitors, identified the inability of these

          safety-related components to provide meaningful radiological

          release information as designed.



(vi)      Number and Location of Components:



          For each unit there are two Nuclear Research Corporation

          Extended Range Gamma Scintillation Detectors [MD-55E(V3)], one

          for each main steam line, located in the MSIV room.



(vii)     Corrective Actions:



          We have communicated the detector performance problem to the

          vendor.  The detectors and associated pre-amplifiers were

          returned to the vendor for confirmatory testing and

          modification, if necessary.  The vendor confirmed that the

          detectors were not operating as expected over the required

          temperature range and that the originally supplied

          environmental test data was incomplete.  A proposed

          modification to the detector temperature compensation circuit

          has been temporarily implemented and is undergoing initial

          vendor testing.



          Baltimore Gas and Electric Company has prescribed additional

          testing to be performed by the vendor on the proposed

          modification.  Following the completion of this testing and BGE

          acceptance of the results, formal factory acceptance testing of

          the modified detectors will occur.  Upon satisfactory

          completion of the factory acceptance testing, BGE acceptance

          testing per approved Engineering Test Procedures will be

          performed.  We plan to conduct this acceptance testing at

          Calvert Cliffs with the units operating and the MSIV rooms at

          elevated temperatures (similar conditions to when the problem

          with the detector response was first identified).  Following

          successful completion of the site acceptance tests, the Unit 1

          and Unit 2 Main Steam Header Radiation Monitors will be

          returned to OPERABLE status.  The estimated completion date for

          the return of all Main Steam Header Radiation Monitors to

          OPERABLE status is August 31, 1997.



          An INPO Nuclear NETWORK message has been issued to make other

          industry personnel aware of this problem.



                                    4



                             ATTACHMENT (1)



               10 CFR PART 21 REPORT CONCERNING FAILURE OF

                  MAIN STEAM HEADER RADIATION MONITORS

                SUPPLIED BY NUCLEAR RESEARCH CORPORATION



(viii)    Other Advice Related to Purchasers or Licensees.



          None.



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