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UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555-0001

March 17, 1998

**Addressees**

All holders of operating licenses for nuclear power reactors except those who have permanently ceased operations and havecertified that fuel has been permanently removed from the reactor vessel.

**Purpose**

The U.S. Nuclear Regulatory Commission (NRC) is issuing this supplement to Information Notice (IN) 95-52, to informaddressees of the results of fire endurance tests for electrical raceway fire barrier systems constructed from 3M CompanyInteram fire barrier materials. It is expected that recipients will review the information for applicability to their facilitiesand consider actions, as appropriate, in their review of Interam fire barriers. However, suggestions contained in thisinformation notice are not NRC requirements; therefore, no specific action or written response is required.

**Background**

In 1995, Peak Seals, Incorporated, initiated a test program to qualify 3M Interam fire barrier designs to Generic Letter (GL)86-10, Supplement 1, "Fire Endurance Test Acceptance Criteria for Fire Barrier Systems Used To Separate Redundant SafeShutdown Trains Within the Same Fire Area." The first objective of Peak Seals was to qualify 3M designs that existedbefore GL 86-10, Supplement 1, to the new requirements. The 3M designs that did not meet the acceptance criteria of GL86-10, Supplement 1, were modified by Peak Seals and retested. IN 95-52 provided the results of 1-hour and 3-hour fireendurance tests that were conducted by Peak Seals at Omega Point Laboratories, San Antonio, Texas. The tests were full-scale fire endurance tests for electrical raceway fire barrier systems constructed from 3M Company Interam fire barriermaterial.

Through correspondence with 3M and Peak Seals, the staff recently obtained the results of two additional 3-hour fireendurance tests of Interam fire barrier configurations conducted by Peak Seals. The following descriptions are based oninformation provided to the staff by 3M Fire Protection Products (Accession number 9802040360) and a letter datedOctober 3, 1997, from Peak Seals (Accession number 9802040354). The staff did not witness these fire endurance tests andhas not reviewed the fire test reports.

**Description of Circumstances**

The information provided to the staff indicated that the 3-hour fire endurance tests described below were conducted inaccordance with American Society for Testing and Materials (ASTM) Standard E-119, "Fire Test of Building Constructionand Materials." The acceptance criteria for temperature specified in GL 86-10, Supplement 1, state that the unexposed sideof the barrier, as measured on the exterior surface of the raceway or component, must not exceed an average temperaturegreater than 250 �F above its initial temperature, or a maximum single point temperature 30 percent greater than theallowable maximum temperature rise, or 325 �F above its initial temperature. For these tests, the ambient temperaturereading on the thermocouples is considered to be the starting temperature.

The first fire endurance test was conducted on November 28, 1995. The test assembly included 1-inch, 3-inch, and 5-inchconduits; a 2-inch air drop; a 12-inch by 12-inch by 8-inch junction box; a 24-inch by 4-inch cable tray; and a 6-inch by 4-inch cable tray. All the items tested were protected with five layers of Interam E54A material. Some temperatures in all ofthe configurations, with the exception of the 2-inch airdrop, exceeded the temperature rise acceptance criteria specified inGL 86-10, Supplement 1. The second fire endurance test was conducted on December 7, 1995. Four 1-inch electricalconduits wrapped with Interam fire barrier material were tested. Two conduits were wrapped with five layers of InteramE54A material, one conduit with the ends sealed, and the other without the ends sealed. One conduit was wrapped with sixlayers of Interam E54A material without the ends sealed, and the fourth was wrapped with seven layers of Interam E54Awithout the ends sealed. The conduit with seven layers of Interam material was the only assembly with a temperature risethat met the temperature rise acceptance criteria specified in GL 86-10, Supplement 1.

**Discussion**

NRC requirements and guidelines for fire barriers are specified in various documents: 10 CFR Part 50, Appendix R, "FireProtection Program for Nuclear Power Facilities Operating Prior to January 1, 1979;" Branch Technical Position APCSB9.5-1, Appendix A, "Guidelines for Fire Protection for Nuclear Power Plants Docketed Prior to July 1, 1976;" NUREG-0800, "Standard Review Plan;" and GL 86-10, "Implementation of Fire Protection Requirements." The extent to whichthese requirements or guidelines are applicable to a specific nuclear power plant depends on the age of the plant,commitments established by the licensee in developing the fire protection plan, the staff safety evaluation reports andsupplements, and the license conditions pertaining to fire protection. These requirements and guidelines provide reasonableassurance that fire barriers will remain in place and retain their integrity when exposed to a fire. By so doing, there isreasonable assurance that the effects of a fire will be limited to discrete fire areas and that one train of systems andcomponents required to achieve and maintain safe shutdown will remain free of fire damage.

On March 25, 1994, the NRC issued Supplement 1 to GL 86-10 to (1) clarify the applicability of the test acceptance criteriain GL 86-10 to raceway fire barrier systems, (2) specify a set of fire endurance test acceptance criteria that are acceptablefor demonstrating that fire barrier systems can perform the required fire-resistive function and maintain the protected safeshutdown train free of fire damage, (3) specify acceptable options for hose stream testing, and (4) specify criteria for cablefunctionality testing when a deviation is necessary, such as when the fire barrier temperature rise criteria are exceeded orthe test specimen cables sustain visible damage.

These positions are used by the NRC staff to review and evaluate fire endurance tests and fire barrier systems proposed bylicensees or applicants to satisfy existing NRC fire protection rules and regulations. Some temperatures observed during thetests in November 1995 and December 1995, previously described herein, exceeded the maximum allowable temperatureacceptance criteria of Supplement 1 to GL 86-10. In accordance with this supplement, an engineering evaluation could beperformed to determine the acceptability of an in-plant Interam fire barrier that was bounded by a deviating test specimenconfiguration. Information about such evaluations can be found in Supplement 1 to GL 86-10.

This information notice establishes no new NRC requirements; therefore, no specific action or written response is requiredby this notice. However, recipients are reminded that they are required by 10 CFR 50.65 to take industry-wide operatingexperience (including information presented in NRC information notices) into consideration, where practical, when settinggoals and performing periodic evaluations. If you have any questions about the information in this notice, please contactthe technical contact listed below or the appropriate Office of Nuclear Reactor Regulation project manager.

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