ML14183A058
| ML14183A058 | |
| Person / Time | |
|---|---|
| Site: | Robinson  |
| Issue date: | 09/17/1986 |
| From: | Novak T Office of Nuclear Reactor Regulation |
| To: | Carolina Power & Light Co |
| Shared Package | |
| ML14183A059 | List: |
| References | |
| NUDOCS 8609290355 | |
| Download: ML14183A058 (14) | |
Text
7590-01 UNITED STATES OF AMERICA NUCLEAR REGULATORY COMMISSION In the matter of Docket No. 50-261 CAROLINA POWER & LIGHT COMPANY H. B. ROBINSON STEAM ELECTRIC PLANT, UNIT NO. 2 EXEMPTION I.
The Carolina Power and Light Company (CP&L, the licensee) is the holder of Operating License No. DPR-23 which authorizes operation of H. B. Robinson Steam Electric Plant, Unit 2. The license provides, among other things, that the H. B. Robinson Steam Electric Plant, Unit 2 is subject to all rules, regulations, and Orders of the Commission now or hereafter in effect.
The station is a single-unit pressurized water reactor at the licensee's site located in Darlington County, South Carolina.
II.
On November 19, 1980, the Commission published a revised Section 50.48 and a new Appendix R to 10 CFR Part 50 reqarding fire protection features of nuclear power plants. The revised Section 5E.48 and Appendix P became effective on February 17, 1981.
Section III of Appendix R contains 15 subsections, lettered A through 0, each of which specified requirements for a particular aspect of the fire protection features at a 8 6 09290355 860917 PDR ADOCK 05000261 F
PDR 7590-01 nuclear power plant. One of these subsections, HTI.G, is the subJect of the licensee's exemption request.
Section III.G.2 of Appendix P requires that one train of cables and equipment necessary to achieve and maintain safe shutdown be maintained free of fire damage by one of the following means:
- a. Separation of cables and equipment and associated nonsafety circuits of redundant trains by a fire barrier having a 3-hour rating.
Structural steel forming a part of or supportinq such fire barriers shall be protected to provide fire resistance equivalent to that required of the barrier.
- b. Separation of cables and equipment and associated nonsafety circuits of redundant trains by a horizontal distance of more than 20 feet with no intervening combustibles or fire hazards.
Tn addition, fire detectors and an automatic fire suppression system shall be installed in the fire area.
- c. Enclosure of cable and equipment and associated nonsafety circuits of one redundant train in a fire barrier having a 1-hour rating. In addition, fire detectors and an automatic fire suppression system shall be installed in the fire area.
Subsectior ITI.G.3 of Appendix R requires that for areas where alternative or dedicated shutdown is provided, fire detection and a fixed fire suppression system shall also be installed in the area, room, or zone under consideration.
III.
By letter dated July 20, 1984, the licensee requested two exemptions from III.G.3 of Appendix R. The first exemption was from the III.G.3 fixed
3 7590-01 suppression requirements for six.plant fire areas. The second exemption was from the III.G.3 fixed suppression and fire detection requirements for a single fire area. On November 30, 1984, the licensee submitted changes in the method of implementing the alternative shutdown capability and this resulted in identifying additional fire zones where credit was taken for the alternative shutdown capability. By letter dated February 13, 1985, the licensee also requested III.(.3 exemptions from the require ments of fixed suppression and fire detection for these new fire zones.
This February 13, 1985 submittal became a "stand-alone" document consolidat ing exemption requests made in the-July 20 and November 30, 1984 submittals.
On March 11, 1985, a meeting was held between the licensee and the NRC, and the licensee submitted additional information in a letter dated May 10, 1985. This information was in the form of fire area drawings, fire detection system NFPA code compliance, diesel oil storage tank NFPA code compliance, and cable tray concentration fire loadings.
Finally, the licensee amended the TII.G.3 Appendix R exemption request by letter dated October 28, 1985.
Py letter dated August 17, 1984, the licensee requested an exemption from Section III.G.?.f to the extent that it would require the Rockbestos cables inside containment be kept "free of fire damaqe."
This submittal also provided technical information previously reouested by the NRC staff.
Ry telecon dated August 4, 1986, the licensee provided informa tion relevant to the "special circumstances" finding required by revised 10 CFR 50.12(a) (See 50 Fed. Reg. 50764).
The licensee stated that existino and proposed fire protection features at H. B. Robinson accomplish the underlying purpose of the rule. Implementing additional modifications to provide additional suppression systems, detection systems, and fire barriers would require the expenditure of engineering and construction 7590-01 resources as well as the associated capital costs which would represent an unwarranted burden on the licensee's resources. The licensee stated that the costs to be incurred are as follows:
a III.G.3 Engineering, procurement and installation of additional detection and suppression equipment - S1,656,000.
III.G.2.f Engineering procurement and installation of radiant energy heat shields -
$61,000.
The licensee stated that these costs are significantly in excess of those required to meet the underlying purpose of the rule. The staff concludes that "special circumstances" exist for the licensee's requested exemptions in that application of the regulation in these particular circumstances is not necessary to achieve the underlying purposes of Appendix R to CFP Part 50. See 10 CFR 50.1?(a)(?)(ii).
The following exemption requests, therefore, reflect the latest status for the areas/zones listed below:
- 1. Auxiliary Building (Fire Area A), Limited to Fire Zones 3, 6, 7, 8, 11, 1?, 13, 15, 16, 17, 18, 21, and 23.
Exemptions were requested from Section III.G.3 to the extent that it requires the installation of fire detection and fixed fire suppression throughout the zones for which an alternative shutdown capability is provided.
- 2. Charging Pump Room, Volume Control Tank Room, and Non-Regenerative Heat Exchanger Room (Fire Area R), limited to Fire Zone 4.
Exemptions were requested from Section III.G.3 to the extent that it requires the installation of fire detection and fixed fire suppression throughout the zones for which an alternative shutdown capability is provided.
7590-01
- 3.
Exterior Area (Fire Area G), limited to Fire Zones 25, 28, 30, 31, 32, and 33.
Exemptions were requested from Section II.G.3 to the extent that it requires the installaticn of fire detection and fixed fire suppressior.
throughout the zones for which an alternative shutdown capability is provided.
- 4. Containment Outside the Missile'Barrier from approximately 900 to 2700 and from 1200 to 2900 at General Elevations 230 Feet to 231*
Feet.
An exemption was requested from III.G.2.f to the extent that it would reouire the Rockbestos cables (serving as a radiant energy heat shield) to be kept free of fire damage.
The licensee requested an exemption from Section III.G.3 to the extent that it requires the installation of fire detection and fixed fire suppression systems throughout the fire zones for which an alternative.
shutdown capability is provided. These fire zones include 3, 6, 7, 8, 11, 12, 13, 15, 16, 17, 18, 21, and 23.
Fire Zones 3, 6, 7, 8, 11, 12, 13, 15, 16, 17, 18, 21, and 23 are all within Fire Area A, the auxiliary buildino.
Construction is composed of reinforced concrete. The fire loadings for all of these zones is low to moderate and in no case is the fire loading such that a fire severity greater than 30 minutes would result.
In the fire zones under consideration, each one contains redundant
-trains of normal safe shutdown systems. However, alternative safe shutdown capability is proposed for each area. In each case, the alternative safe shutdown capability will be electrically independent from the zone under consideration. Passive safe shutdown equipment, such as tanks, heat exchangers, and manually operated valves, which are relied upon in their current location, have been evaluated and shown to be available.
6 -7500-01 The existing fire protection includes early warning fire detection except for fire zones 12 and 13, fire extinguishers in each zone as well as hose station coverage. Fire Zone 7 has a partial area preaction sprinkler system.
The fire protection in these fire zones does not comply with the technical requirements of Section III.G.3 of Appendix R because fire detection and fire suppression systems 'have not been installed throuqhout the fire zones for which an alternative shutdown capability is provided.
The staff was concerned that a fire in one of these fire zones could cause a loss of norrmal shutdown capability. However, the fuel load in Fire Zones 3, 6, 7, 8, 11, 1?, 13, 15, 16, 17, 18, 21, and 23 is low (less than 38,000 Btu per souare foot).
Because of the low to moderate combustible loading, the staff does not anticipate a fire of significant magnitude or duration to occur. Except for Fire Zones 12 and 13, fire detection is available in each of these zones and elsewhere throughout the auxiliary building. Therefore, we have reasonable assurance that a fire in these locations will be detected during its early stages and extinguished by the fire brigade before adjacent safety-related areas are threatened.
In Fire Zones 3, 11, 1?, and 16, passive safe shutdown equipment is located and relied upon for the protection of redundant safe shutdown trains. In the case of valves, manual action is not needed for over 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> and, since the fire loadings are low (maximum of a 23-minute fire severity), ample time exists for the fire brigade to extinguish the fire and manually operate the valve(s).
Heat exchangers are filled with water and exposed to only low fire loading; therefore, the staff has reasonable assurance that anticipated fires would not damaae them.
7--
7590-01 Should a fire damage any normal safe shutdown components in Fire Zones 6, 7, 8, 13, 15, 17, 18, 21, and 23 before the fire brigade extinguishes the fire, alternative shutdown capability is available-to be used to achieve and maintain safe shutdown.
Based on the staff's evaluation, the staff concludes that the existing fire protection features already in place combined with the alternative shutdown capability in the above described fire zones provide a level of protection equivalent to the technical requirements of Section III.G.3 of Anpendix R.
The licensee also requested an exemption from Section TII.G.3 to the extent that it requires installation of fire detection and fixed fire suppression systems throuphout Fire Zone 4 and Fire Area R for which alternative shutdown capability is provided.
Fire Zone 4 of Fire Area 9 is enclosed by 3-hour fire barriers.
The fire loading is 18,500 Btu per square foot and this translates into a 13-minute fire severity as represented by the ASTM E-119 fire test curve. Hence, this is a low fire loading.
Fire Zone 4 contains safe shutdown equipment; however, the designated alternative shutdown method for Fire Area B is alternative train B. Train B is completely independent of Fire Area B.
The existing fire protection includes fire extinguishers, hose station coverage, and a fire detection system using heat and ionization detectors.
The staff was concerned that a fire in this fire zone could cause a loss of normal shutdown capability. However, the fire load in Fire Zone 4 is low (less than 19,000 Btu per souare foot).
Because of the low combustible fire loading, the staff does not expect a fire of significant
)7590-01 magnitude or duration to occur. Should a fire damage normal safe shutdown components in this fire zone before extinguishment by the fire brigade, the alternative shutdown capability is available to be used to achieve and maintain safe shutdown.
Based on our evaluation, the staff concludes that the existing fire protection features already in place, combined with the alternative shutdown capability in the above described fire zone, provide a level of protection equivalent to the technical requirements of Section III.G.3 of Appendix R.
The licensee also requested ai-exemption from Section III.G.3 to the extent that it requires installation of fire detection and fixed fire suppression systems throughout Fire Zones 25, 28, 30, 31, 32, and 33 for which an alternative shutdown capability is provided.
Fire Zones 25, 28, 30, 31, 32, and 33 are all within Fire Area G.
The fire load per square foot was not calculated for the exterior areas in Fire Zones 25 and 30. The other fire zones have a negligible fire loading.
Each of the fire zones under consideration contains redundant trains of normal safe shutdown systems.
However, alternative safe shutdown capability is proposed for each area. In each case, the alternative safe shutdown capability (alternative train 8) will be electrically independent from the zone under consideration except for Fire Zones 30, 31, and 33. These three zones contain train R safe shutdown components. Fire Zone 30 contains the 25,000-gallon diesel fuel oil tank and diesel oil transfer pumps that fuel diesel generators A and B. The A and B diesel day tanks are independent of Fire Area G, and they contain a 16-hour supply of fuel.
However, the dedicated 7590-01 shutdown diesel (a third diesel) has an independent fuel supply and this equipment is more than 500 feet away from Fire Zone 30. Therefore, emergency power is available from two separate locations given a fjre in Fire Zone 30.
Fire Zone 31 contains the refueling water storage tank, which is required for the alternative safe shutdown system. This tank is located outside. This is true also for the condensate storage tank in Fire Zone 33.
For the other fire zones in Fire Area G, alternative shutdown is completely independent.
Fire protection exists in Film Zone 25 in the form of an early warning fire detection system and a partial deluge fire suppression system. Also, fire extinguishers and hose stations are available. The other fire zones under consideration in Fire Area G are open to the outside environment and there are yard hydrants available with fire hoses.
The staff was concerned that a fire in one of these fire zones could cause a loss of normal shutdown capability. However, the fire loads in Fire Zones 25, 28, 30 (except for the diesel fuel), 31, 32, and 33 are low and, therefore, the staff does not anticipate that a fire of significant magnitude or duration would occur. In the case of Fire Zone 25, a fire detection system exists and, hence, a fire would be detected in its early stages and extinguished by the fire brigade before adjacent safety-related areas are threatened. In the other fire zones, the fire would be in the exterior, and heat would escape and dissipate directly without threatening safety-related equipment.
Should a fire damage any normal safe shutdown components in Fire Zones 25, 28, 30, 31, 32, and 33 before the fire brigade extinguishes the fire, the alternate shutdown capability is available and/or remains in tact to be used to achieve and maintain safe shutdown.
10 -
759G-C Based on our evaluation, the staff concludes that the existing fire protection features already in place, combined with the alternate shutdown capability in the above described fire zones, provide a level of protection equivalent to the technical requirements of Section_
III.G.3 of Appendix R.
The licensee also requested exemption from Section III.G.2.f to the extent that it would require the-Rockbestos cables (serving as a radiant energy heat shield) to be kept free of fire damage in the containment.
The licensee has committed to use Rockbestos cables for service of the alternate shutdown system steam generator level transmitters and steam generator A hot leg and cold leg resistance temperature detectors.
There is about a 14-to 19-foot vertical separation between the Rockbestos cables and the cable trays above. These alternate shutdown instruments are used to provide data input to indicators located on the charging pump room panel and the turbine deck panel.
The fire loading in containment includes 960 pounds of charcoal for a fire load of 2000 Btu per square foot and 200 gallons of lube oil per reactor coolant pump, which results in a 20,000 Btu per square foot per pump bay. A fire severity of less than 20 minutes would be associated with the above fire loadings.
Fire protection is in the form of fire extinguishers and manual hose stations. The electrical penetration area has fire detection and a preaction sprinkler system. Each reactor coolant pump has a preaction sprinkler system which minimizes the oil fire hazards.
The technical requirements of Section III.G.2.f are not met in the containment area because certain alternate shutdown-related instrument cables, delineated in the licensee's August 17, 1984 letter, are not
11 -
7590-01 protected by a radiant energy heat shield and would not be free of fire damage after being involved in a fire.
The staff had a number of concerns with the use of "fire-rated'I cable in lieu of a conventional radiant energy heat shield. The first was that, when exposed to the effects of a fire, the cable would not perform its intended function. By letter dated June 13, 1984, the Licensee submitted the results o a fire test conducted by Underwriter's Laboratories. In the procedure, represen tative samples of the cable were subjected to a 1-hour fire endurance and hose stream test in accordance with the method in ASTM E-119. During the fire test and for a period of 93 hours0.00108 days <br />0.0258 hours <br />1.537698e-4 weeks <br />3.53865e-5 months <br /> beyontd; electrical measurements were taken to confirm the.cable's electrical performance. The results confirm that the acceptance criteria of ASTM E-119 were met or exceeded. We, therefore, have reasonable assurance that the cables will function as designed until the fire is extinguished.
We were also concerned that the heat produced in a fire would cause structural features such as cable trays to collapse. The falling debris might impact the cable and cause its failure. The Rockbestos cables will be in conduits and supported on the missile wall on unistrut type supports, which keep the cable/conduit close to the wall.
Therefore, falling debris will not pull it down and, because of the low fire loading, insufficient heat will be generated to cause support failure. The fire brigade could easily extinguish the fire using manual equipment.
With regard to voltage, the subject cable will be used at 24 Vdc, and the Rockbestos cables have been fire tested at voltages of 110 Vac, 480 Vac, and 960 Vac. Therefore, there is no concern about its use at high voltages.
Because the fire-rated cable would be damaged by a fire, we were concerned that this damage would affect the performance of the shutdown functions for a time period that is significantly longer than the time period for which the
12 7590-01 function is required. The proposed use of this cable is to provide a radiant energy heat shield for use inside containment. The cables were subjected to an ASTM E-119 fire test, and the circuit integrity was maintained and -kept functional for a period of 93 hours0.00108 days <br />0.0258 hours <br />1.537698e-4 weeks <br />3.53865e-5 months <br />. Rockbestos cables were previously evaluated and accepted by the NRC for use where a 1-hour fire-rated barrier was required by Appendix R. This acceptance was granted for TMI via an NRC letter dated April 19, 1985. The intent of a radiant energy heat shield for use inside containment was to offer a lesser level of passive fire protection than a 1-hour barrier.
This was in recognition of the fact that the containment fire hazards tended to be low and containment was not susceptible to the degree of transient fires expected to occur outside of containment. Therefore, we conclude that the Rockbestos cable is quite conservative for the heat shield application, given minor fire damage that would be expected to occur inside containment.
For the distributed fire load in this area, it would be difficult to achieve a real fire that would result in temperatures approaching the E-119 time-temperature curve over a large portion of the fire area. Prompt action by the fire brigade would further reduce the time-temperature curve. The hose stream tests with repeated application of hose stream forces have resolved this concern.
We were concerned that thermal expansion forces, and post-fire mechanical forces due to fire fighting and recovery operations, were not simulated. We were also concerned that "wet short" conditions were not simulated, in that cables in cable trays may be immersed in water for a significant time. The installation proposed by the Licensee is for conduits, and hose streams would not disrupt the cables. These cables, being in conduit, would not be immersed in water. These two concerns are resolved.
13 -
7590-01 Based on the above evaluation, the staff concludes that the use of Rockbestos fire rated cables in lieu of a radiant energy heat shield inside containment provides a level of fire protection equivalent to the technical requirements of Section III.G.?.f of Appendix R.
IV.
Accordingly, the Commission has determined that, pursuant to 10 CFR 50.12(a), that (1) these exemptions as described in Section III are authorized by law, will not present an undue risk to the public health and safety, and are consistent with the common defense and security and (2) special circumstances are present -for the exemptions in that application of the regulation in these particular circumstances is not necessary to achieve the underlying purposes of Appendix R to 10 CFR Part 50. Therefore, the Commission hereby grants the following exemptions from the requirements of Section III.G of Appendix R to 10 CFR Part 50:
- 1. Auxiliary Building (Fire Area A), limited to Fire Zones 3, 6, 7, 8, 11, 12, 13, 15, 16, 17, 18, 21, and 23 to the extent that automatic fire detection and suppression systems are not installed throughout the zones pursuant to III.G.3.
- 2. Charging Pump Room, Volume Control Tank Room, and Non-Regenerative Heat Exchanger Room (Fire Area B) limited to Fire Zone 4 to the extent that automatic fire detection and suppression systems are not installed throughout the zones pursuant to III.G.3.
- 3. Exterior Area (Fire Area G), limited to Fire Zones ?5, 28, 30, 31, 32, and 33 to the extent that automatic fire detection and suppression systems are not installed throughout the zones pursuant to III.G.3.
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7590-01
- 4. Containment Outside the Missile Barrier from approximately 90' to 2700 and from 1200 to 2900 at General Elevations 230 Feet to 235 Feet to the extent that the Rockbestos cables be kept free of.fire damace pursuant to III.G.2.
Pursuant to 10 CFR 51.32, the Commission has determined that the granting of these exemptions will have no significant impact on the environment (51 FR 32979) dated September.17, 1986.
A copy of the Safety Evaluation dated September 17
, 1986, related to this action is available for public inspection at the Commission's Public Document Room, 1717 H Street, NV, Washington, D.C. and at the local public document room located at the Hartsville Memorial Library, Home t Fifth Avenue, Hartsville, South Carolina 29550. A copy may be obtained upon written request addressed to the U.S. Nuclear Regulatory Commission, Washington, D.C. 20555, Attention: Director, Division of PWR Licensing-A.
This Exemption is effective upon issuance.
FOR THE NUCLEAR REGULATORY COMMISSION Thomas M. Novak, Acting Director Division of PWR Licensing-A Office of Nuclear Reactor Regulation Dated at Bethesda, Maryland, this l7th day of September, 1986